WO2017121345A1 - 一种改进的电化学分析方法及应用 - Google Patents

一种改进的电化学分析方法及应用 Download PDF

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WO2017121345A1
WO2017121345A1 PCT/CN2017/070944 CN2017070944W WO2017121345A1 WO 2017121345 A1 WO2017121345 A1 WO 2017121345A1 CN 2017070944 W CN2017070944 W CN 2017070944W WO 2017121345 A1 WO2017121345 A1 WO 2017121345A1
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sample
amalgam
metal
dissolution
liquid mercury
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French (fr)
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刘文涛
刘哲龙
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刘文涛
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/48—Systems using polarography, i.e. measuring changes in current under a slowly-varying voltage

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  • the invention belongs to the technical field of heavy metal detection, and in particular relates to an improved electrochemical analysis method and application.
  • Non-standard analytical methods are usually not scientifically certified by experts in relevant national departments, such as the method for measuring Cd, Pb and Cu in seawater samples by anodic stripping voltammetry, edited by Xu Kuncan et al.
  • Standard analytical methods have the disadvantages of poor comparability and non-authority.
  • the standard analysis method is an analytical method that has been scientifically verified by experts of relevant national departments. For example, in the national standard GB 17378.4-2007 "Marine Monitoring Specification", the measurement of Pb in seawater, etc., the standard analysis method has good comparability, accuracy and Authoritative, only standard analytical methods can be applied in environmental monitoring and enforcement.
  • the detection limit is Specified detection concentration, if converted to quantitative detection concentration, is an order of magnitude difference. It can be seen from the technical indicators that the anodic stripping voltammetry is an analytical method with quantitative detection ability of ⁇ g/L. The advantage is that the sample does not need to be treated, and the Zn, Cd, Pb and the seawater or fresh water can be directly measured. Cu; Disadvantages: poor reproducibility.
  • the detection limit of Pb in seawater is measured by flame atomic absorption spectrophotometry 0.03 ⁇ g/L, that is, the quantitative detection concentration of Pb is 0.3 ⁇ g/L, which can be seen from the technical indicators.
  • the flame-free atomic absorption spectrophotometry is also an analytical method with quantitative detection capability of ⁇ g/L.
  • Advantages Measure Cd, Pb and Cu in fresh water samples. The samples do not need to be processed and can be directly measured. The measurement process is simple and fast. Disadvantages; only the measurement of Pb in seawater samples or freshwater samples often results in poor reproducibility.
  • ICP-MS Inductively coupled plasma mass spectrometry
  • HY/T147.1-2003 "Technical Regulations for Marine Monitoring”
  • Pb in seawater is detected.
  • the limit is 0.07 ⁇ g / L, that is, the quantitative detection concentration is only 0.7 ⁇ g / L, the technical index is slightly lower than the quantitative detection concentration of 0.3 ⁇ g / L by flame atomic absorption spectrophotometry.
  • ICP-MS measures Pb in fresh water with a minimum detection mass concentration of 0.07 ⁇ g/L, ie a quantitative detection concentration of 0.07 ⁇ g/L.
  • the disadvantage is: relatively expensive, high cost, is a high-end analytical instrument.
  • flameless atomic absorption spectrophotometry can meet the measurement of ⁇ g/L Pb in seawater or freshwater samples.
  • flame-free atomic absorption spectrophotometry is an analytical method based on the quantitative detection ability of Pb in the seawater or fresh water from the processing, washing and measurement of samples, so it accumulates Ten years of ⁇ g/L Pb of seawater or freshwater raw data.
  • the object of the present invention is to solve the problem that the Pb in the seawater or fresh water sample is inaccurate in the existing standard analysis method, and to provide a quantitative detection capability based on the ng/L level from the processing, washing and measurement of the sample. Analytical method.
  • the potentiometric stripping method is based on the following reaction formula:
  • the specific steps are as follows: 1) collecting samples and performing sample processing to obtain an acidic sample containing the electrolyte, so that the metal in the sample to be tested exists in the form of ions and can conduct electricity; 2) washing the electrolytic cell and liquid mercury; Zn and / or Cd ion solution is added to the sample to be tested, and then measured by a polarograph.
  • the present invention obtains an improved electrochemical analysis through experimental results and theoretical analysis.
  • the method, the sample collection method, the sample processing method, the electrolytic pool washing method and the measuring method in the method are optimized to solve the problem that the Pb in the clean seawater or fresh water sample is inaccurate in the prior art.
  • Figure 1-12 shows the dissolution profiles in Experiments 1-12.
  • the seawater discussed in the present invention refers to seawater on the shore, offshore and in the open sea, and does not include the seawater of the sewage outlet; fresh water refers to the unpolluted or less polluted reference water source, low salt content of rivers, rivers, groundwater, etc. Fresh water samples, excluding fresh water from the drain.
  • Pb having a concentration lower than 0.03 ⁇ g/L referred to as Pb of ng/L grade
  • Pb having a concentration ranging from 0.3 to 2.5 ⁇ g/L which is referred to as Pg of ⁇ g/L grade.
  • Pb of ng/L grade a concentration lower than 0.03 ⁇ g/L
  • Pg of ⁇ g/L grade a concentration ranging from 0.3 to 2.5 ⁇ g/L
  • anodic stripping voltammetry is an electrochemical analysis method that detects the peak height of the dissolution peak and the enrichment time.
  • anodic stripping voltammetry It is called reverse stripping voltammetry.
  • the basic process is divided into two steps: firstly, the metal ion to be tested is pre-electrolyzed on the working electrode for a certain time to be enriched under a constant voltage which is more negative than its peak potential. Then, the potential is scanned from the negative to the positive direction, and the substance concentrated on the electrode is oxidized and dissolved, and the oxidation wave thereof is recorded.
  • the composition of the substance to be tested is determined based on the peak potential of the dissolution, and the content of the substance to be tested is determined according to the height of the oxidation wave.
  • the whole process can be expressed as:
  • Mn + represents a metal ion including, but not limited to, Zn, Cd, Pb, and Cu ions.
  • Electrolytic reduction is a slow enrichment, dissolution is a sudden release, and thus the Faraday current as a signal is greatly increased, thereby greatly increasing the sensitivity of the method. If the existing anodic stripping voltammetry can be strictly followed, in the enrichment reaction, Zn, Cd, Pb, Cu, Sn, Te, Bi, Ni, Ga, In, Ti, and Co can be measured in the sample to be tested.
  • Metal ions are enriched in the liquid mercury of the working electrode of the silver-based mercury film (in the present invention, "silver-based mercury film working electrode liquid mercury” can be simply referred to as “liquid mercury”) to form Zn, Cd, Pb, Cu, Sn, Te, Bi, Ni, Ga, In, Ti, and Co amalgam can not only measure the elution peaks of Zn, Cd, Pb, and Cu when performing the dissolution reaction, but theoretically, Sn, Te, Bi, and A dissolution peak of a metal such as Ni, Ga, In, Ti, and Co.
  • a metal such as Ni, Ga, In, Ti, and Co.
  • the enrichment time is long enough, not only can the Pb elution peak of ⁇ g/L level in seawater or freshwater samples be measured, but also the dissolution peak of ng/L grade Pb should be measured, and even the ratio ng/L can be measured.
  • Grade Pb has a lower concentration of Pb elution peak, so the present invention employs anodic stripping voltammetry.
  • the potential stripping method is exactly the same as the enrichment reaction of the existing anodic stripping voltammetry.
  • the potentiometric stripping method is based on the existing anodic stripping voltammetry, which leads to the same rich Set the reaction.
  • the total reaction formula of the potential stripping method is: Hg 2+ + 2e ⁇ Hg
  • the existing potentiometric stripping method is exactly the same as the enrichment reaction of the existing anodic stripping voltammetry. It can be seen from the enrichment reaction and the elution reaction of the potentiometric stripping method that the potentiometric stripping method is also detected.
  • the analysis method related to the concentration and enrichment time if the measurement principle of the potential dissolution method is correct, as long as the enrichment time is long enough, not only It can measure the Pb elution peak of ⁇ g/L grade in seawater or freshwater samples, and can also measure the elution peak of ng/L grade Pb, and even measure the Pb elution peak of lower concentration than ng/L grade Pb.
  • the present invention only uses the anodic stripping voltammetry as an example to conduct an experiment and a detailed discussion, and the correct conclusion of the anodic stripping voltammetry is used to infer the enrichment reaction and the dissolution reaction of the correct potentiometric stripping method.
  • the correct conclusion of the anodic stripping voltammetry is used to infer the enrichment reaction and the dissolution reaction of the correct potentiometric stripping method.
  • the "existing analytical method" in the present invention means: using the existing anodic stripping voltammetry, the principle of measurement is the existing anodic stripping voltammetry enrichment reaction and dissolution reaction,
  • the existing analysis conditions refer to 1) the bottom liquid of the analysis sample is acidic, the purpose is to make the metal of the sample to be tested in the form of ions; 2) the seawater sample and the fresh water sample must contain a certain amount of electrolyte, so fresh water A certain amount of electrolyte is usually added to the sample in order to make the bottom liquid of the analytical sample conductive; to meet the normal progress of the existing anodic stripping voltammetry enrichment reaction and dissolution reaction.
  • Zn, Cd, Pb and Cu ions are simply referred to as target ions, and Zn, Cd, Pb and Cu amalgam are simply referred to as target ion amalgams; in addition to Zn, Cd, Pb and the sample to be tested
  • Other metal ions other than Cu such as Sn, Te, Bi, Ni, Ga, In, Ti, and Co, are simply referred to as interfering metal ions; Sn (Hg), Te (Hg), Bi (Hg), Ni (Hg), Metal amalgams such as Ga(Hg), In(Hg), and Ti(Hg) are simply referred to as interfering amalgams.
  • ng/L Pb seawater or river water samples should be collected. Uncontaminated seawater or freshwater samples should be selected. Ideal seawater samples should theoretically choose offshore seawater. Due to the many factors involved in collecting seawater in the open sea. The limitation of (ship), the seawater sample for experimental use of the present invention, the seawater of the bank of Yinhaida World in Shinan District, Qingdao City was selected; the freshwater sample of the experiment of the present invention was selected as the river upstream of the northern Jiu Shui Scenic Area of Lushan Mountain, Qingdao.
  • Container for sample Since there is no washing method for washing ng/L Pb vessels at home and abroad, the Pb concentration of high quality mineral water produced by regular manufacturers is very low, which is close to ng/L (Pb). Therefore, the washing process of the mineral water bottle can meet the requirement of containing the ng/L grade Pb sample, and the washing method is to wash the mineral water bottle several times by adding an appropriate amount of acid in the collected ng/L grade sample; The ng/L sample vessels are washed with the mineral water bottle by this method, and will not be separately explained below.
  • the sample Since this experiment is an analytical method involving the measurement of ng/L grade Pb, the sample must be processed in accordance with ng/L grade (Pb). At present, the sample is generally filtered through a membrane with a pore size of 0.45 ⁇ m and then added. Acid-acidified sample processing method, although filtration can prevent the particles and organisms suspended in the sample from causing high measurement results, acidification can also prevent adsorption phenomenon. However, this is a sample processing method that establishes Pb in seawater or fresh water on a ⁇ g/L basis.
  • the sample treatment is adsorbed, it is usually possible to bring 30% or 50% low, but the probability of being on the order of magnitude is small, so although the contamination and adsorption will bring measurement error, the adsorption band The resulting error may theoretically be smaller and closer to the true value. Therefore, regarding the processing of ng/L grade samples, it is recommended to select a sample treatment method that avoids contamination. 1) Without filtering without acid, the collected sample is placed directly in the sample vial, and the sample is allowed to stand for 3-12 h. The static setting is used to minimize the influence of suspended particles and organisms on the measurement results, and the supernatant is measured during the measurement. The advantage is that there is no contamination.
  • the disadvantage is that it is only suitable for the measurement of very clear seawater or fresh water samples on the same day; it can not eliminate the influence of suspended particles and organisms on the measurement results; it is not easy to store for a long time because the sample does not add acid. Adsorption will occur, resulting in lower measurement results. 2) Do not filter and add acid without acid addition. The sample is allowed to stand for 6-36h. If the time is too long, the adsorption phenomenon will occur, resulting in low measurement results. Therefore, it is recommended to be 6-36h.
  • the specific operation process is to introduce the supernatant of the sample after standing into another sample bottle, and add an appropriate amount of acid to acidify and store the sample.
  • the advantage is that there is no stain, and the suspended particles in the sample are minimized by the method of standing.
  • the effect of the measurement results can save the sample for a long time, but can not completely eliminate the effect of suspended particles and organisms on the measurement results, and is suitable for more clear sample processing.
  • Do not filter and add acid do not stand the sample collected, add appropriate amount of acid to acidify the sample, the advantage is that there is no contamination, no adsorption phenomenon will occur. Disadvantages, only suitable for special locations, special sampling time, etc. Strictly limited collection of very clear sample processing, theoretically can not completely eliminate the impact of suspended particles and organisms in the sample on the high measurement results.
  • For centrifugation of the sample it is suitable for the more turbid sample collected on the day.
  • the method is to centrifuge with a centrifuge-specific vessel, take the supernatant, transfer it to another vial, and add an appropriate amount of acidified sample.
  • the advantage is that the suspended particles in the sample can be quickly and minimized to prevent adsorption.
  • the washing workload of the special vessel for the centrifuge is very large, and it is preferable to change the special vessel for the centrifuge to the above-mentioned mineral water bottle.
  • Adsorption sample processing method suitable for samples that cannot be centrifuged on the sample collected on the same day. The method is to use two or more containers to collect samples, preferably using a washed mineral water bottle, and let it stand for more than 12 hours.
  • each Adsorption occurs in each container, the suspended particles in the sample will naturally settle, disturb one of the containers A and pour off the sample.
  • the purpose is to pour the suspended particles deposited on the bottom of the container with the sample to obtain an empty container that has been adsorbed. Transfer the supernatant B of the sample in the other container which has also been adsorbed to the container A, and then add an appropriate amount of the acidified sample, and the Pb adsorbed to the inner wall of the container A is redissolved in the supernatant B.
  • the method can minimize the influence of the adsorption phenomenon, so that the Pb concentration in the sample is as close as possible to the true value of the sample.
  • the present invention adopts the method 3) the sample processing method which does not filter the acid, and the sample processing method which does not filter the acid to collect the sample weather, collect the sample time, and collect the sample.
  • the location is limited: the weather of the seawater sample is collected, usually the wind is small, the sea water is clear, the weather is fine; the time of collecting the sample is selected after about one hour after the low tide of the seawater; the location of the sample is collected, and the distance is selected as far as possible from the shore.
  • the seawater in the larger water body remaining in the larger concave reef, the seawater sample of the larger water body in the larger concave reef is the natural precipitation after several hours, and the suspended particles in the sample are minimized. Therefore, the effect of suspended particles on the measurement results can be minimized.
  • For the freshwater samples collected usually choose the wind water in the upper reaches of the northern Jiu Shui Scenic Area in Lushan, Qingdao.
  • the invention measures Pb of ng/L grade
  • the present invention optimizes the process of collecting, processing and measuring the sample, and thus can be completed in a laboratory environment of level 100 and ultra-clean. Measurements can be done in a relatively closed laboratory environment. Measurement can be done in a normal relatively closed laboratory environment, which is also a very big breakthrough in analytical techniques, and will be very important for the promotion of this analytical method.
  • the present invention adopts a multi-function polarograph manufactured by Qingdao Polarographic Instrument Co., Ltd. for dustproof treatment, and the work of the polarograph
  • the electrode uses a silver-based mercury film electrode
  • the reference electrode uses a silver chloride silver reference electrode or a calomel reference electrode
  • the auxiliary electrode uses a platinum electrode.
  • reagent Pb standard solution, 1000ug/ml, GSB G 62071-90; Cd standard solution, 1000ug/ml, GSB G 62040-90; Cu standard solution, 1000ug/ml, GSB G 62024-90; In standard solution, 1000ug /ml, GSB G 04-1731-2004; the standard use solution used was obtained by diluting the above mother liquor.
  • the 1:2 nitric acid solution was a mixture of 1 volume of nitric acid and 2 volumes of water.
  • the 5% zinc chloride solution is obtained by dissolving 5.0 g of zinc chloride in 100 ml of ultrapure water; the 0.1% zinc chloride solution is taken as 2 ml of a 5% zinc chloride solution, diluted to 100 ml, and formulated into a 0.1% zinc chloride solution.
  • the purpose of adding approximately Zn, Cd, Pb and Cu standard solutions is to increase Zn, Cd, Pb and Cu in the sample. At the ion concentration, more pronounced Zn, Cd, Pb, and Cu elution peaks were observed.
  • the enrichment time is modified to 30 seconds. First, the enrichment reaction is carried out, and the Zn, Cd, Pb and Cu ions in the sample to be tested are enriched in liquid mercury to reduce Zn (Hg) and Cd. (Hg), Pb (Hg), Cu (Hg) amalgam, referred to as Zn, Cd, Pb and Cu amalgam.
  • the elution reaction is further carried out, and the potential is scanned from the negative to the positive direction to oxidize and dissolve the substance concentrated on the electrode, and the oxidation wave, ie, the elution spectrum, is recorded, see the dissolution spectrum 1-1.
  • the peak potential of Pb elution is usually about -0.4 V, and the peak potential of Cu elution is usually about -0.2 V.
  • the samples of different media have slightly changed the potential of the elution peak.
  • the anodic stripping voltammetry is an analytical method for calculating the concentration by dissolution spectrum.
  • the dissolution spectrum of the sample to be tested is first measured. See the dissolution spectrum 1-1, and the measurement is performed several times in succession.
  • the peak height to be measured is stable and repeated, and the standard is added.
  • the peak height of the two stable repeats of the last measurement is usually taken.
  • the peak heights of the last two Cd dissolution peaks are 13.38 and 13.70, respectively.
  • the peak heights of the last two Pb dissolution peaks are 2.52 and 3.13, respectively.
  • the peak heights of the two Cu dissolution peaks were 22.61 and 23.49, respectively.
  • the peak height of dissolution peaks of Cd, Pb and Cu increased significantly.
  • two peaks of stable and repeated spikes were taken, and the peak of Cd dissolution was measured. The heights were 29.96 and 29.67, respectively.
  • the peak heights of Pb dissolution peaks were 12.11 and 11.53, respectively.
  • the peak heights of Cu dissolution peaks were 47.52 and 46.98, respectively.
  • the concentration of Cd, Pb and Cu can be calculated separately according to the formula for calculating the concentration by anodic stripping voltammetry.
  • the abscissa is the voltage
  • the unit is volt (V)
  • the ordinate is the peak current, expressed by the peak height value
  • the dissolution spectrum is exactly the same as the representation of the abscissa and the ordinate of Fig. 1 or Fig. 2, so the abscissa and the ordinate are not detailed in the following dissolution spectrum
  • two in Fig. 1 Repeated spectra are repeatedly displayed. When many spectra are repeatedly displayed, it is difficult to accurately express the spectrum to be expressed. Therefore, in other spectral displays, only one of the repeated spectra is displayed. .
  • the anodic stripping voltammetry can measure the dissolution peaks of stably repeating Cd, Pb and Cu by using the existing analysis conditions, and prolong the enrichment time, and the measured elution peaks of Cd, Pb and Cu can also be increased. Therefore, if the measurement principle of the existing anodic stripping voltammetry is correct, as long as the enrichment time is long enough, theoretically, the elution peak of ng/L grade Pb can be measured, and the experiment is verified by experiment 2, anodic stripping voltammetry The analytical conditions of the existing analytical methods were used to test whether the Pb elution peak in clean seawater could be measured.
  • the washing method of the electrolytic cell, the liquid sampling amount of the clean seawater sample, the analysis conditions, and the instrument parameter setting were the same as those in the experiment 1, and the enrichment was 360 s, and the dissolution spectrum 2-1 was obtained.
  • the enrichment time was extended to 999 seconds, and the other operating conditions were unchanged, and the dissolution spectrum 2-2 was obtained.
  • the experimental results show that the Pb elution peak can not be measured by prolonging the enrichment time, which proves that the existing anodic stripping voltammetry is not an electrochemical analysis method related to the detected peak height and enrichment time. This phenomenon cannot be reasonably explained by the measurement principle of the existing anodic stripping voltammetry enrichment reaction and dissolution reaction.
  • Experiment 3 used clean fresh water for experimental verification.
  • the washing method, sample amount, analysis conditions and instrument parameters of the electrolytic cell were the same as those in Experiment 1.
  • 8 drops of saturated KCl solution were added to increase electrolyte and enrich.
  • a dissolution spectrum 3-1 was obtained.
  • the enrichment time was extended to 999 seconds, and the other operating conditions were unchanged, and the dissolution spectrum 3-2 was obtained.
  • the Zn, Cd, Pb and Cu amalgams enriched in liquid mercury may recombine with the interfering amalgam enriched in liquid mercury.
  • the reaction can be expressed as:
  • R n+ - represents a metal ion capable of forming a dissolution peak, including but not limited to Zn, Cd, Pb, and Cu ions, that is, a target ion
  • N n+ - represents a metal ion that cannot form a dissolution peak, that is, an interference metal ion
  • R ( Hg) – indicates a metal amalgam capable of forming a dissolution peak, including but not limited to Zn, Cd, Pb, and Cu amalgam, ie, the target amalgam
  • N(Hg) – indicates a metal amalgam that does not form a dissolution peak, ie, interfering with mercury Qi
  • RN- represents an intermetallic compound.
  • Zn, Cd, Pb and Cu amalgams enriched in liquid mercury may recombine with interfering amalgams enriched in liquid mercury to form intermetallic compounds such as those in Table 1. .
  • the enrichment time is not enough, resulting in the concentration of Pb amalgam enriched in liquid mercury. Low; the other is Pb amalgam enriched in liquid mercury, and a recombination reaction occurs before the dissolution reaction to form an intermetallic compound related to Pb.
  • Cu which is enriched in Cu amalgam in liquid mercury
  • Cu amalgam can recombine with mercury to form Cu amalgam, which will result in only Cu amalgam, no Pb amalgam, Cd amalgam, when performing the dissolution reaction.
  • the phenomenon of interference with the metal amalgam occurs, only the elution peak of Cu can be measured, and the phenomenon of Pb elution peak, Cd elution peak, and interference metal elution peak cannot be measured.
  • Zn, Cd, Pb, and Cu amalgam enriched in liquid mercury, interference amalgam, and liquid mercury remain at a certain concentration related to Pb and Cd.
  • Intermetallic compounds and intermetallic compounds associated with interfering metals continue to recombine, leaving Pb and Cd in the intermetallic compounds associated with Pb and Cd in liquid mercury, or recombined with mercury, continuing to form Pb and Cd Related intermetallic compounds; Pb amalgam enriched in liquid mercury, Pb, Cd in Cd amalgam, or all re-engaged with mercury, but combined with metals other than mercury, formed with Pb and Cd Related intermetallic compounds, the concentration of intermetallic compounds associated with Pb and Cd metals in liquid mercury continues to increase; at the same time, the interfering metals in the liquid mercury that interfere with the amalgam are still no longer recombined with mercury.
  • the invention adds a higher concentration of Zn ions (the only changed condition) to the sample to be tested, so that the total concentration of Zn, Cd, Pb and Cu ions in the sample to be tested is greatly increased, and Zn is enriched in liquid mercury.
  • the total concentration of Cd, Pb, and Cu amalgam will be much greater than the total amalgam or metal concentration associated with interfering amalgams and intermetallic compounds associated with interfering metals.
  • the interfering metal in the intermetallic compound associated with the interfering metal in a certain concentration in liquid mercury continues to combine with metals other than mercury to continue to form intermetallic compounds related to interfering metals, while enriching into liquid mercury.
  • Interfering metals in amalgam still fail to recombine with mercury, but combine with metals other than mercury to form intermetallic compounds associated with interfering metals, which leads to concentrations of intermetallic compounds associated with interfering metals in liquid mercury. Continue to increase and cannot be removed.
  • the dissolution reaction since there is no interference in the presence of the amalgam in the liquid mercury, the phenomenon that the metal elution peak is not detected can be measured.
  • the generated Cd amalgam will measure the higher Pb elution peak and the higher Cd elution peak in Fig. 4. Since Pb and Cd-related intermetallic compounds remaining in liquid mercury can also be converted into Pb and Cd amalgams to form Pb and Cd elution peaks, the Pb elution peak and Cd elution peak measured by the analysis conditions of the present invention are observed. Can not be cleaned as a calculation The dissolution peak of Pb concentration and Cd concentration in the seawater sample, otherwise the measurement result is seriously high.
  • the anodic stripping voltammetry uses existing analytical conditions, from the inability to measure the Pb elution peak in a clean seawater sample, to the Pb elution peak using the analytical conditions of the present invention.
  • the results of this experiment can prove that Wang Erkang et al.
  • the idea of intermetallic compounds is established or correct.
  • the results of the experiments also demonstrate that Zn, Cd, Pb and Cu amalgams in liquid mercury recombine with interfering amalgams.
  • the anodic stripping voltammetry enrichment reaction of the present invention can be obtained by the above analysis, which is obtained by superposing the recombination reaction on the basis of the existing anodic stripping voltammetry enrichment reaction;
  • the azide of Zn, Cd, Pb and Cu can form a dissolution peak, and the interference amalgam cannot form a dissolution peak. Therefore:
  • the enrichment reaction can be expressed as:
  • the dissolution reaction can be expressed as: R n+ +ne(+Hg) ⁇ R(Hg).
  • the enrichment reaction and the dissolution reaction of the potentiometric stripping method of the present invention are as follows:
  • the enrichment reaction can be expressed as:
  • the dissolution reaction can be expressed as: R(Hg) + 1/2O 2 + 2H + ⁇ R 2+ + Hg + H 2 O.
  • the anodic stripping voltammetry enrichment reaction and dissolution reaction, potentiometric stripping enrichment reaction and dissolution reaction of the present invention are very important for guiding us to correctly measure the concentrations of Cd, Pb and Cu in samples such as seawater and fresh water. significance. Since the enrichment reaction of the anodic stripping voltammetry of the present invention is completely the same as the enrichment reaction of the potentiometric stripping method of the present invention, the principle of the enrichment reaction and the dissolution reaction of the potentiometric stripping method according to the present invention, and the analysis conditions of the present invention are used. It is also within the scope of the present invention to measure metals such as Cd, Pb, and Cu, as described herein.
  • anodic stripping voltammetry enrichment reaction of the present invention is obtained by superposing a recombination reaction on the basis of the existing anodic stripping voltammetry enrichment reaction, and thus the anodic stripping voltammetry of the present invention
  • Enrichment reaction and dissolution reaction, as well as potentiometric stripping enrichment reaction and dissolution reaction, in terms of accurate expression, may have expression defects, which is also reasonable.
  • anodic stripping voltammetry is essentially a metal such as Pb that will be enriched in liquid mercury (other metals refer to Pb, but also Cd or Cu or Zn).
  • the amalgam, the interference amalgam, and the method of measuring the elution reaction after recombination reaction between the intermetallic compound related to the metal such as Pb and the intermetallic compound related to the interfering metal in the liquid mercury are essentially a metal such as Pb that will be enriched in liquid mercury (other metals refer to Pb, but also Cd or Cu or Zn).
  • Experiment 5 was continued on the basis of the dissolution spectrum 3-2 in Experiment 3, and 30 ⁇ L of a Cd standard solution having a concentration of 2 mg/l was added to the sample to be tested (here, a Cd standard solution was selected instead of the Cd-containing ion. Reagent), to increase the total concentration of Zn, Cd and Pb in the sample to be tested, to verify whether the Pb elution peak can be measured by adding Cd ions to the sample to be tested using the analysis conditions of the present invention.
  • the instrument parameters are set exactly the same as the instrument parameters in Figure 3-2, and are again enriched, scanned for dissolution, and the dissolution spectrum is shown in Figure 5.
  • the elution peak of Cu in Experiment 5 is obviously increased because the Cu in the clean fresh water sample is measured by the analysis conditions of the existing analytical method, and the metal such as Cu in the sample to be tested can be used.
  • Pb or Cd or Zn) ions are enriched in liquid mercury to form metal amalgams such as Cu, and interfering metal ions can be enriched into liquid mercury to form interfering amalgam. Due to the lower total concentration of Zn, Cd and Pb ions in clean fresh water samples, and the lower concentration of Cu ions in clean fresh water samples, this leads to Zn, Cd and Pb amalgam in liquid mercury.
  • the total concentration is less than the amalgam or the total concentration of amalgam or metal in the intermetallic compound associated with the interfering metal, enriched in liquid mercury to form a metal amalgam such as Cu and interfering with amalgam, and remains in liquid mercury.
  • Intermetallic compounds related to interfering metals recombine in liquid mercury, Cu in metal amalgams such as Cu enriched in liquid mercury, recombined with mercury in a certain ratio (number) to form Cu amalgam
  • the remaining part of Cu combines with a metal other than mercury to form an intermetallic compound related to Cu, which causes the occurrence of intermetallic compounds associated with metals such as Cu in liquid mercury; residual liquid mercury and interference Interfering metals in metal-related intermetallic compounds, or in combination with metals other than mercury, continue to form intermetallic compounds associated with interfering metals; enriched in liquid mercury to interfere with amalgams Scrambling metal, in addition to mercury in combination with a metal, intermetallic compound of the metal associated with the interference, which will cause the concentration of liquid mercury in interference between the
  • the total concentration of Zn, Cd and Pb amalgam in liquid mercury is not changed due to the measured total concentration of Zn, Cd and Pb ions in the clean fresh water sample, and the interference in liquid mercury
  • the amalgam or total metal concentration in the amalgam and intermetallic compounds associated with interfering metals enrichment into liquid mercury to form metal amalgams such as Cu and interfering with amalgam, and residual in liquid mercury associated with Cu
  • the intermetallic compound and the intermetallic compound associated with the interfering metal will also recombine in liquid mercury, and the Cu in the intermetallic compound associated with Cu remaining in liquid mercury will continue to recombine with metals other than mercury. Continued formation of Cu-related intermetallic compounds remains in liquid mercury.
  • Cu in metal amalgams such as Cu enriched in liquid mercury is recombined with mercury in the same proportion (number) to form Cu amalgam, and the remaining part of Cu continues to combine with metals other than mercury to form An intermetallic compound associated with Cu, which causes a continuous increase in the concentration of Cu-related intermetallic compounds remaining in liquid mercury.
  • the Cu in the metal amalgam such as Cu, which is enriched in liquid mercury, is recombined with mercury in the same ratio (number) at the previous time to form Cu amalgam, and the measurement can be measured. Low stable phenomenon of repeated Cu dissolution peaks.
  • the washing method of the electrolytic cell, the sample liquid take-off amount, and the instrument parameter setting are the same as those in Experiment 2.
  • the enrichment is 360s, and the dissolution spectrum 6-1 is obtained.
  • the enrichment time is extended to 999s, and the dissolution spectrum 6-2 is obtained.
  • the enrichment and dissolution were repeated several times, and the elution peaks of Cd, Zn and Pb in the clean seawater samples could not be measured.
  • the phenomenon that the elution peak of Cu can be measured is the same as that of the experiment 4. The detailed explanation is shown in Experiment 4.
  • a Pb standard solution having a concentration of 10 mg/l is added to the sample to be tested (here, a Pb standard solution is selected instead of the reagent containing Pb ions) to increase the Zn, Cd and the measured sample.
  • the total concentration of Pb ions, without changing any parameters, continue to measure, scan for dissolution, and the dissolution spectrum is shown in Figure 6-3. It can measure the Pb elution peak at full scale, and the higher Cd and Zn elution peaks, and the Cu dissolution peak is obvious. Increase.
  • the anodic stripping voltammetry uses the existing analytical conditions and has the ability to measure 1 ⁇ g/L Pb of ⁇ g/L seawater samples.
  • the problem is that the anodic stripping voltammetry uses existing analytical conditions to determine (more accurate) 1 ⁇ g. /L Pb's ability to ⁇ g/L seawater samples?
  • seawater or fresh water containing 1 ⁇ g/L Pb which is called a cleaner seawater or freshwater sample. If the measurement result is 1 ⁇ g/L, it can be inferred that the recovery rate is 100%.
  • the instrument parameters are set according to the instrument default parameters.
  • the enrichment time is 60 seconds.
  • Start measurement, scan dissolution, see dissolution spectrum 7-1 can measure Pb dissolution peak, continuously measure 2 Pb dissolution peaks, peak height is 1.17 and 1.29, The two peak heights measured continuously were stable.
  • continue to add 40 ⁇ L of Pb standard solution with concentration of 1mg/L to the sample to be tested continue to measure, scan for dissolution, see dissolution spectrum 7-2, Pb elution peak is obviously increased, and continuous measurement of two Pb dissolution peak heights respectively
  • the samples were also stably repeated and calculated according to the formula for calculating the concentration by anodic stripping voltammetry at a concentration of 0.05 ⁇ g/L.
  • the recovery rate is only 5%.
  • the Pb in the 1 ⁇ g/L seawater sample is measured. The measured result is seriously low, and the recovery rate is also seriously low.
  • the anodic stripping voltammetry can measure 1 ⁇ g/L Pb in seawater samples using the analytical conditions of the existing analytical methods, it is possible to measure the stable repeating Pb elution peak before spiked and the stable repeated spiked Pb elution peak. Under the premise, but the measurement results are seriously low, the recovery rate is only 5%. Why the anodic stripping voltammetry uses the analytical conditions of the existing analytical methods to measure 1 ⁇ g/L Pb in a relatively clean seawater sample, under the premise of measuring the stable repeating spike and the spiked Pb elution peak, The result is seriously low?
  • intermetallic compounds associated with interfering metals remaining in liquid mercury recombine in liquid mercury, interfering with metal interfering metals in liquid mercury
  • Interfering metals in intermetallic compounds, in combination with metals other than mercury continue to form intermetallic compounds associated with interfering metals, interfering metals in interfering amalgams enriched in liquid mercury, and also in combination with metals other than mercury.
  • the formation of intermetallic compounds related to interfering metals which leads to an increase in the concentration of intermetallic compounds associated with interfering metals in liquid mercury, which cannot be reduced, so that the number of samples measured by the working electrode of the silver-based mercury film is increased.
  • the concentration of the intermetallic compound will also be higher.
  • the intermetallic compounds associated with interfering metals after the enrichment reaction, result in a lower total concentration of Zn, Cd and Pb in liquid mercury due to the lower total concentration of Zn, Cd and Pb ions in the clean seawater sample.
  • the concentration is slightly less than or close to the amalgam and the total concentration of amalgam or metal in the intermetallic compound associated with the interfering metal, enriched in liquid mercury, such as Pb and other metal amalgams and interfering amalgam, will be associated with liquid mercury
  • Residual higher concentrations of intermetallic compounds associated with metals such as Pb and higher concentrations of intermetallic compounds associated with interfering metals recombine in liquid mercury, and higher concentrations in liquid mercury are associated with metals such as Pb.
  • Pb in the intermetallic compound, or in combination with metals other than mercury continue to form Pb-related intermetallic compounds; due to the presence of higher concentrations of interfering metals in liquid mercury The reason for the intermetallic compound, resulting in the enrichment of liquid mercury in a metal such as Pb, Pb amalgam,
  • a metal such as Pb in the compound continues to bind to a metal other than mercury, and continues to form an intermetallic compound related to Pb, and Pb in a metal amalgam such as Pb enriched in liquid mercury is still in the same ratio as in the previous time ( Recombination with mercury to form Pb amalgam, the remaining (large) portion of Pb continues to bind to metals other than mercury, resulting in Pb-related intermetallic compounds, which will result in residual liquid mercury Inter-related and Pb metal continues to increase the concentration of the compound.
  • the Pb in the metal amalgam such as Pb enriched in liquid mercury is recombined with mercury in the same proportion (number) and the Pb amalgam is formed, a severely low stable and repeated spike can be measured.
  • Pre-Pb elution peak In order to calculate the concentration of Pb in the relatively clean seawater sample, 40 ⁇ L of the Pb standard solution with a concentration of 1 mg/l was added to the sample to be tested, and after the enrichment reaction was again carried out, the Pb standard at a concentration of 1 mg/L was added to the sample to be tested.
  • the reason for the 40 ⁇ L solution is that the total concentration of Zn, Cd and Pb amalgam in liquid mercury is significantly increased, while the concentration of amalgam or total metal in the intermetallic compounds involved in the amalgam and interfering metals in liquid mercury is only slightly increased.
  • metal amalgams such as Pb and interfering amalgams, as well as intermetallic compounds and higher concentrations of intermetallic compounds associated with interfering metals in liquid mercury. It will also recombine the reaction in liquid mercury, and Pb in the metal amalgam such as Pb enriched in liquid mercury will increase the ratio of recombination with mercury, resulting in more Pb amalgam and remaining.
  • Pb in an intermetallic compound related to a metal such as Pb in liquid mercury will also be recombined with mercury in a certain ratio (number) or all to form a Pb amalgam.
  • Pb formed in Pb amalgam enriched in liquid mercury Pb amalgam formed, and Pb formed by conversion of Pb in intermetallic compounds related to metals such as Pb in liquid mercury Amalgam will measure the severely high Pb elution peak.
  • the Pb in the intermetallic compound associated with the metal such as Pb remains in the liquid mercury due to the (previous dissolution reaction). Or most or all of it combined with re-mercury to form Pb amalgam, which enters the sample to be tested through the dissolution reaction.
  • the total concentration of Zn, Cd and Pb ions in the sample to be tested is slightly increased, resulting in liquid mercury.
  • the total concentration of Zn, Cd and Pb amalgam in the liquid mercury, and the amalgam or total metal concentration in intermetallic compounds related to interfering amalgam and interfering metals in liquid mercury The proportion (number) of the degree changes, enriched in liquid mercury to form metal amalgam such as Pb and interfering amalgam, and there are intermetallic compounds and higher concentrations remaining in liquid mercury with higher concentrations of metals such as Pb.
  • Intermetallic compounds related to interfering metals recombining in liquid mercury, enriched in Pb in metal amalgams such as Pb in liquid mercury, recombined with mercury in the last close ratio (number) to form Pb Amalgam, and the proportion of Pb in the intermetallic compounds associated with metals such as Pb in liquid mercury is greatly reduced, and the ratio (number) of mercury recombination can be greatly reduced. Instead, it recombines with mercury or no longer recombines with mercury in a significantly lower ratio (number) than the previous one to produce a Pb amalgam.
  • Pb in a metal amalgam such as Pb enriched in liquid mercury recombines with mercury in a ratio close to the last time to form a Pb amalgam, and remains in liquid mercury and Pb.
  • the Pb in the metal-related intermetallic compound is recombined with mercury or recombined with mercury in a significantly lower ratio (number) than the previous one to form a Pb amalgam, and the measured Pb elution peak will be compared.
  • the Pb elution peak measured at one time was significantly lower (not repeated). Although the measured Pb elution peak was significantly lower than the last measured Pb elution peak, the measured Pb elution peak was still severely high.
  • the total concentration of Zn, Cd, and Pb amalgam in liquid mercury is not changed due to the change in the total concentration of Zn, Cd, and Pb ions in the relatively clean seawater sample being measured, and in liquid mercury.
  • the enrichment of metal amalgam and interfering amalgam such as Pb in liquid mercury will be in liquid mercury.
  • the same ratio (number) is recombined with mercury to form Pb amalgam, and the Pb remaining in the intermetallic compound related to metal such as Pb in liquid mercury is also the same ratio (number) and mercury Recombination to generate Pb amalgam.
  • Pb in a metal amalgam such as Pb enriched in liquid mercury recombines with mercury in the same ratio (number) at one time to form Pb amalgam, and remains in liquid mercury and metal such as Pb.
  • the Pb in the related intermetallic compound is also recombined with mercury in the same ratio (number) at the same time, and also generates Pb amalgam.
  • the spiked Pb elution peaks with severely high and stable repeats were measured.
  • the anodic stripping voltammetry of the present invention or the analytical method of the present invention is measured by the anodic stripping voltammetry enrichment reaction and the dissolution reaction of the present invention.
  • the analysis conditions of the present invention are: 1) The bottom liquid of the sample is acidic, the purpose is to make the metal of the sample to be in the form of ions; 2) the seawater sample and the fresh water sample must contain a certain amount of electrolyte, so a certain amount is usually added to the fresh water sample.
  • the electrolyte is designed to make the bottom liquid of the analytical sample conductive; to meet the normal progress of the existing anodic stripping voltammetry enrichment reaction and dissolution reaction.
  • the first problem is to solve the ng/L Pb washing problem of the electrolytic cell, and the second is to remove or eliminate the Pb-related metal between the residual liquid mercury.
  • the problem that the compound interferes with the measurement, and the third is to prevent the Pb enriched in the Pb amalgam in the liquid mercury, and then combine with the metal other than the mercury to form a Pb-related intermetallic compound.
  • the washing of ng/L grade Pb in the electrolytic cell since there is no ng/L grade Pb washing method or washing technique at home and abroad, the difficulty lies in the use of the existing washing method, using acidic ultrapure water or other washing.
  • the Pb elution peak of the measured washing liquid is less than or equal to or very close to the Pb eluting peak of the sample to be tested, it can be inferred that liquid mercury or electrolytic cell Pb cleaned Or very close to washing clean. It should be explained that the Pb elution peak of the measured washing liquid is equal to or very close to the Pb eluting peak of the sample to be tested.
  • the washing liquid can only select the sample to be tested.
  • the washing liquid as for the washing of fresh water, the washing liquid is also selected in accordance with this principle.
  • the washing in this experiment is a measurement elution washing method.
  • the Pb elution peak of the washing liquid is measured by the analysis conditions of the present invention, the washing liquid is replaced, and the Pb elution peak is measured again, and the measured peak height is compared with the previous Pb elution.
  • the peak-to-peak height is significantly reduced, indicating the presence of Pb contamination in the electrolytic cell and liquid mercury; thus, using the analytical conditions of the analytical method of the present invention, the concentration of the washing liquid is used to separate the metal associated with the metal such as Pb remaining in the liquid mercury.
  • the Pb in the compound is first converted into a Pb amalgam, and then introduced into the washing liquid by dissolution to realize the washing of the electrolytic cell in the intermetallic compound related to the metal such as Pb remaining in the liquid mercury.
  • the washing of the Pb in the electrolytic cell is achieved by measuring the acid washing liquid and using the difference in the concentration of the washing liquid.
  • the washing liquid was changed several times and the Pb elution peak was measured until the measured peak height was no longer significantly reduced or equal to the previous peak, and the washing liquid used here could theoretically only be washed to such an extent. Is the washed electrolytic cell and Pb in liquid mercury cleaned? Then, the same analysis conditions (instrument parameters and analysis conditions) are used to measure the Pb elution peak of the sample to be tested.
  • the Pb elution peak height of the measured sample is equal to or greater than or very close to the Pb eluting peak height of the washing liquid, it can be inferred.
  • the liquid mercury or Pb in the electrolytic cell is washed or very close to washing. If the Pb elution peak height of the measured sample is less than the Pb elution peak height of the washing liquid, it can be inferred that the liquid mercury or the Pb in the electrolytic cell is not washed clean, and the measure or the replacement for the cleaner washing liquid can be taken.
  • the sample is used as a washing liquid, and the peak height of the Pb elution peak is continuously compared until the Pb eluting peak height of the test sample is equal to or greater than or very close to the Pb eluting peak height of the washing liquid, which is the measured dissolution washing of the present invention. law.
  • the measured dissolution washing method of the present invention is adopted, and the sample to be tested is used for the washing liquid, 20 mL of a clean seawater sample having a pH of 3-4, 30 ⁇ L of a 0.1% ZnCl solution, and 0.4 mg/L are added. 30 ⁇ L of CdCl solution.
  • the instrument parameter setting is consistent with the default parameters, enriched for 220s. After the enrichment reaction, the total concentration of Zn, Cd and Pb amalgam in liquid mercury is far due to the higher total concentration of Zn, Cd and Pb in the washing liquid.
  • the peak height of the elution peak of the amount Pb was 25.84.
  • This Pb elution peak is a Pb amalgam which is enriched in liquid mercury, and a Pb elution peak formed by Pb amalgam which is formed in liquid mercury.
  • the Pb elution peak can also be formed due to the Pb amalgam which is also formed in the liquid mercury, so the Pb elution peak with a measured peak height of 25.84 is severely high.
  • the total concentration of Cd and Pb amalgam is much greater than the concentration of amalgam or metal in the interstitial amalgam and intermetallic compounds associated with interfering metals in liquid mercury, enriched in liquid mercury to form metal amalgams such as Pb and interfere Amalgam, and intermetallic compounds related to metals such as Pb and residual intermetallic compounds related to interfering metals in liquid mercury, recombined in liquid mercury, enriched in metal amalgam such as Pb in liquid mercury Pb, recombined with mercury to form Pb amalgam, Pb remaining in liquid mercury in intermetallic compounds related to metals such as Pb, also recombined with mercury to form Pb amalgam.
  • the Pb elution peak in the elution spectrum of Fig. 8-2 was measured, and the peak height of the elution peak of Pb was measured to be 15.78. Since the remeasurement of the Pb elution peak is remarkably lowered, it is inferred that the Pb in the electrolytic cell and the intermetallic compound associated with the metal such as Pb remaining in the liquid mercury is not washed clean, and the reduced Pb elution peak is still enriched. Pb amalgam formed in liquid mercury, and Pb elution peak formed by Pb amalgam formed in liquid mercury.
  • the experimental results show that the concentration of Pb-related intermetallic compounds remaining in liquid mercury is decreasing, and it is in the presence of liquid mercury and Pb.
  • the washing of Pb in the metal-related intermetallic compound is carried out by using the difference in the concentration of the washing liquid, and converting the Pb remaining in the intermetallic compound associated with the metal such as Pb in the liquid mercury under the analysis condition of the present invention.
  • the Pb amalgam is then introduced into the washing liquid by means of dissolution, and the washing of the Pb in the intermetallic compound related to the metal such as Pb remaining in the liquid mercury is realized, and the washing of the electrolytic cell is performed by measuring the acid washing.
  • the washing of the Pb in the electrolytic cell is achieved by using the difference in the concentration of the washing liquid.
  • the total concentration is much greater than the total amalgam or metal concentration in the interstitial amalgam and intermetallic compounds associated with interfering metals in liquid mercury, enriched in liquid mercury to form metal amalgams such as Pb and interfering amalgams, and Intermetallic compounds associated with metals such as Pb and intermetallic compounds associated with interfering metals in liquid mercury, recombined in liquid mercury, enriched in Pb in metal amalgams such as Pb in liquid mercury, and mercury Recombination, the formation of Pb amalgam, Pb remaining in the intermetallic compounds associated with metals such as Pb in liquid mercury, also recombined with mercury to form Pb amalgam.
  • the Pb elution peak in the elution spectrum of Fig. 8-3 was measured, and the peak height of the elution peak of Pb was measured to be 5.03. Since the remeasurement of the Pb elution peak is remarkably lowered, it is inferred that the Pb in the electrolytic cell and the intermetallic compound associated with the metal such as Pb remaining in the liquid mercury is not washed clean, and the reduced Pb elution peak is still enriched. Pb amalgam formed in liquid mercury, and Pb elution peak formed by Pb amalgam formed in liquid mercury. Pour off the sample and take 20ml again The clean seawater samples are subjected to the same analytical conditions.
  • the total concentration of Zn, Cd and Pb in the liquid mercury is high due to the high concentration of Zn, Cd and Pb in the sample.
  • Intermetallic compounds related to metals such as Pb and intermetallic compounds related to interfering metals recombine in liquid mercury
  • Pb in metal amalgams such as Pb enriched in liquid mercury recombines with mercury to form Pb Amalgam
  • Pb in intermetallic compounds associated with metals such as Pb in liquid mercury is also recombined with mercury to form Pb amalgam.
  • the Pb elution peak in the elution spectrum of Fig. 8-4 was measured, and the peak height of the elution peak of Pb was measured to be 4.91. Since the re-measured Pb elution peak is no longer significantly reduced, it is inferred from the principle of measuring the elution washing method that the electrolytic cell and the Pb remaining in the liquid mercury are in close contact with the metal in the intermetallic compound such as Pb, so that the electrolytic cell is cleaned. The problem of washing Pb in the intermetallic compound associated with metal such as Pb in liquid mercury is solved.
  • the Pb elution peak measured at this time is the Pb ion in the sample to be tested.
  • the Pb elution peak formed by the Pb amalgam formed in liquid mercury is also the Pb elution peak closest to the true value (including the reagent blank), so do not pour off the sample and continue to measure the Pb elution peak of the sample to be tested.
  • the total concentration of Zn, Cd, and Pb amalgam in liquid mercury is not changed due to the change in the total concentration of Zn, Cd, and Pb ions in the measured clean seawater sample, and the interference amalgam in liquid mercury.
  • the Pb elution peak in the dissolution spectrum of Fig. 8-6 was measured, and the peak height of the elution peak of Pb was measured to be 16.92.
  • the enrichment reaction is measured repeatedly, the total concentration of Zn, Cd and Pb in liquid mercury is higher due to the higher concentration of Zn, Cd and Pb in the sample, and the interference amalgam and interference metal in liquid mercury.
  • the analysis conditions of the present invention can measure the Pb elution peaks before and after the spiked spikes, and the Pb elution peaks formed by the same ratio (number) of Pb ions in the sample to be tested, and the liquid state Intermetallic compounds related to metals such as Pb in mercury, as well as intermetallic compounds associated with interfering metals, no longer interfere with the measurement, and the accuracy of the measurement results is greatly improved.
  • the concentration formula is calculated according to the concentration of anodic stripping voltammetry. Calculated at a concentration of 15.74 ng/L.
  • the measured ng/L level Pb is accurate, measure the recovery rate, continue to add 50 ⁇ L of 0.025 mg/l Pb standard solution to the sample to be tested, and scan for dissolution, see dissolution spectrum 8-7, The Pb elution peaks were measured continuously for 34.97 and 33.53, respectively, and the same stability was repeated. The calculated concentration was 55.21 ng/L, and the calculated recovery was 105.25%. The good recovery rate can be inferred.
  • the anodic stripping voltammetry adopts the analytical method of the present invention. Analysis of the conditions, the measured Pb in the clean seawater sample is 15.74 ng / L is accurate.
  • the analysis method of the present invention Due to the analysis method of the present invention, there is a defect that the reagent blank cannot be deducted, and the sample processing method used in the experiment The theory theoretically leads to a high measurement result. Therefore, the Pb in the clean seawater measured by the analysis method of the present invention can only be theoretically high and cannot be low. From this, it is inferred that the clean seawater measured by the present invention, that is, the Pb in the shore seawater of the Silver Sea World in Shinan District, Qingdao, has a true result (in theory) lower than 15.74 ng/L.
  • the detailed washing process is the same as Experiment 8.
  • Take 20 ml of clean acidic (pH 3-4) fresh water, add 30 ⁇ L of 0.1% ZnCl and 30 ⁇ L of CdCl with a concentration of 0.4 mg/l, and add 2 ml of clean seawater.
  • the purpose of adding seawater is to replace the electrolyte with KCl. , reduce reagent blanks.
  • the instrument parameter settings are consistent with the default parameters, the enrichment time is 180 seconds, the scanning dissolution is performed, and the dissolution spectrum is shown in Figure 9-1.
  • the peak heights of Pb dissolution peaks are 1.78 and 1.76.
  • the Pb elution peak height was continuously measured twice to 15.16 and 13.72 stable repetition, and the calculated concentration was 44.60 ng / L, the recovery rate is 92.14%, a good recovery rate, it can be inferred that the measured 13.18 ng / L results are accurate, also if the analysis method of the present invention can not be deducted reagent blank and the sample processing method used in the present invention Theoretically, it will lead to high measurement results, so the real result (theoretically) is lower than the result of 13.18ng/L. This result can prove that Patterson's proposed "Pb in river water is about 0.015. This ng/L grade river water sample of ppb" does exist.
  • Pb in freshwater samples for domestic and foreign analysts, and also have non- Often important significance. Unlike Pb in seawater, Pb in freshwater samples is affected by many factors, and there is no certain distribution law. However, the result of Pb in clean fresh water samples is 13.18ng/L. At least it can be inferred. Pb from ng/L to ⁇ g/L is possible. If we use a sample for processing and washing based on ⁇ g/L, the measurement is based on a minimum detection quality. A flame atomic absorption spectrophotometric method with a concentration of only 2.5 ⁇ g/L to measure samples ranging from ng/L to ⁇ g/L (Pb).
  • the analysis method of the present invention is more accurate than the existing analysis conditions for measuring 1 ⁇ g/L of ⁇ g/L grade Pb.
  • the washing of the electrolytic cell theoretically measuring the Pb of ⁇ g/L grade, is much less difficult than the measurement of the washing of ng/L grade Pb, but whether measuring the ⁇ g/L grade Pb or measuring the ng/L grade Pb, as long as the measurement wash is satisfied
  • the Pb elution peak of the liquid is lower than or equal to the Pb elution peak in the sample to ensure clean (Pb), so for measuring Pg of ⁇ g/L grade, it is usually washed 1-2 times by the existing washing method.
  • the instrument parameters are set according to the default instrument parameters of the instrument.
  • the enrichment time is 30 seconds, the sensitivity is 10, the measurement is started, the scanning is dissolved, and the dissolution spectrum is shown in Figure 10-1.
  • the peak height of the Pb dissolution peak is 2.20.
  • Peak The peak height (2.20) proves that the Pb in the electrolytic cell and liquid mercury is cleaned and continues to measure. Add 1 mg/L of Pb standard solution to the sample to be tested, and after 40 ⁇ L, scan and dissolve, see dissolution profile 10-3. The Pb dissolution peak was significantly increased. The peak heights of Pb dissolution were 23.47 and 23.37, respectively. The calculated concentration was 1.06 ⁇ g/L, and the recovery was 106%. Good recovery rate can be inferred to measure the clean seawater samples. The 1 ⁇ g/L ⁇ g/L grade Pb is accurate, as detailed in Experiment 8.
  • the soil sample treatment in this experiment is a wet digestion method using nitric acid-hydrochloric acid-perchloric acid which is often used at home and abroad.
  • the weighed soil sample is placed in a digestion vessel, and then an appropriate amount of nitric acid and hydrochloric acid are added to heat the hot plate.
  • Boiling digestion (the process of acid digestion can be one or more times), to be digested to near dryness, then add perchloric acid to further digest to near dryness, then add appropriate amount of nitric acid and water to boil, and the treated soil sample is adjusted to 10 ml. Precipitate for 1-2 days and measure again.
  • the electrolytic cell was washed using the measured dissolution washing method of the present invention, and the washing process was the same as in Experiment 10.
  • the analysis method of the present invention adds (ultra-high concentration) ZnCl 300 ⁇ L at a concentration of 5% to the sample to be tested.
  • the enrichment time is 30 seconds
  • the sensitivity is 6
  • the measurement is started
  • the scanning is dissolved
  • the dissolution spectrum is shown in Figure 11-1.
  • Pb standard solution was added to the sample to be tested. After 30 ⁇ L, the solution was eluted, and the dissolution spectrum 11-2 was observed.
  • the peak heights of the two Pb dissolution peaks were 27.96 and 29.40, respectively, and the calculated concentration was 5.31 ⁇ g/L.
  • measure the recovery rate add 50 ⁇ L of 4mg/l Pb standard solution to the sample to be tested and continue to measure the scanning dissolution. See the dissolution spectrum 11-3, continuously measure the Pb dissolution peak height twice.
  • the calculated result is 13.58 ⁇ g/L
  • the calculated recovery is 103.4%
  • the good recovery rate proves that it is accurate to measure the Pb in the soil sample by the analytical method of the present invention.
  • the existing anodic stripping voltammetry uses existing analytical conditions, and can also measure heavy metals such as Pb in complex samples such as soil, but it is necessary to use a strong base to adjust the pH and reuse the strong acid medium sample.
  • liquid mercury contains a high concentration of Zn amalgam
  • a high concentration of H ions does not interfere with the measurement, and a stable and repeated dissolution spectrum can be measured. Therefore, adding Zn ions with higher or higher concentration or exceeding the concentration in the sample to be tested can prevent the higher or high concentration of H ions in the sample to be absorbed into the liquid mercury to cause hydrogen interference, which can be measured.
  • Experiment 11 was established on the basis of anodic stripping voltammetry using existing analytical conditions to measure metals such as Pb in complex samples of soil and other media, although anodic stripping voltammetry uses existing
  • the analysis conditions can also measure metals such as Pb in complex samples such as soil, but the pH of the low liquid must be adjusted back to weakly acidic, but the anodic stripping voltammetry uses the analytical conditions of the present invention to add high in the sample to be tested.
  • a good recovery rate indicates that the concentration of 1 ⁇ g/L of In can be accurately measured by adding an appropriate amount of Zn ions to the sample to be tested by using the analysis conditions of the present invention.
  • This experiment is based on the anodic stripping voltammetry using existing analytical conditions, can also be measured on the basis of In, as to why In can be measured because there is indeed In amalgam in liquid mercury, but the use of the present invention
  • By analyzing the conditions it is possible to prevent In amalgam enriched in liquid mercury from combining with metals other than mercury to form an intermetallic compound related to In, and therefore the analysis conditions of the present invention measure the concentration of In to be lower, and the measurement result is also more accurate. See Experiment 8 for a detailed explanation. It should be noted that Experiment 8 is a measurement of Pb, but the interpretation of Pb is also applicable to In, so the measurement of In is not explained in detail in the present invention.
  • the focus of the measurement of the present invention is also Pb, so the actual measurement is In the test conditions, the appropriate conditions for adding Pb ions to the sample to be tested are rarely or not used at all.
  • the purpose of the experiment here is simply to prove that the addition of an appropriate concentration of Pb ion solution to the sample to be tested can be controlled.
  • the recombination reaction in liquid mercury proceeds to the left, and the Cd elution peak can be measured, and the Cu elution peak is markedly increased.
  • the best analytical condition for measuring Pb at a lower concentration than ⁇ g/L is to add an appropriate amount of Zn ions to the sample to be tested and then add an appropriate amount of Cd ions, which is beneficial to the measured ratio ⁇ g/L.
  • Lower concentrations of ng/L Pb elution peaks are more stable and repeatable.
  • the most commonly used analysis is to add an appropriate amount of Zn ions to the sample to be tested. This analytical condition facilitates the simultaneous measurement of Cd, Pb and Cu.
  • the metal exists in the form of ions to ensure the enrichment reaction and the dissolution reaction of the anodic stripping voltammetry, and the analysis of the low-liquid using a weakly acidic medium can prevent the H ions in the sample to be measured and enriched into liquid mercury.
  • the reduction produces hydrogen and interferes with the measurement of the dissolution spectrum, which is beneficial for measuring a more stable and repeated dissolution spectrum.
  • the enrichment reaction and the dissolution reaction of the voltammetry proceed smoothly, and a lower concentration or a higher concentration or an ultra-high concentration of Zn ions are added to the sample to be tested, so that a medium acidity medium can be used for the analysis of the low liquid.
  • the purpose or effect of adding (lower concentration or higher concentration or ultra-high concentration) Zn ions to the sample 1. preventing the sample being higher or High concentration of H ions, enriched in liquid mercury to reduce hydrogen to produce interference to the measured dissolution spectrum, is conducive to the measurement of a more stable and repeated dissolution spectrum; 2, to prevent the accumulation of Pb and other metals in liquid mercury Amalgam, interfering with amalgam in enriched liquid mercury, and recombination of intermetallic compounds associated with interfering metals in liquid mercury to form intermetallic compounds associated with metals such as Pb.
  • the purpose or effect of adding (lower or higher concentration) Cd ions to the sample is primarily to measure a more stable repeat of the ng/L grade Pb dissolution peak. Therefore, the analysis conditions of the present invention add Zn and/or Cd ions to the sample to be tested, not only considering metal amalgam and interfering amalgam such as Pb enriched in liquid mercury, but also Pb remaining in liquid mercury. Metal-related intermetallic compounds and intermetallic compounds related to interfering metals recombine in liquid mercury to form intermetallic compounds related to metals such as Pb, and also consider higher or higher concentrations in the sample to be tested. Whether H ions can interfere with the measurement of the dissolution spectrum and whether a stable and repeated dissolution peak can be measured.
  • the present invention adds the amount of Zn and/or Cd ions to the sample to be tested, and usually chooses to add an excess of Zn and/or Cd ions. How to control the excess or the appropriate amount?
  • Zn elution peak It is a suitable amount to measure the Zn elution peak of a large or full scale. If the measured Zn elution peak is small, it is necessary to add a Zn ion reagent until a large or full scale Zn elution peak can be measured.
  • the amount of Cd ions added to the sample to be tested is usually an appropriate amount to measure a large (or full scale or significant) Cd elution peak. Therefore, the maximum upper limit of Zn and Cd is found to be 2% and 0.2%, respectively.
  • the minimum amount of Zn and/or Cd ions added in the present invention, or the recombination reaction occurring in liquid mercury, is a reaction between each metal amalgam and a metal to metal in each intermetallic compound, and the reaction mechanism is very complicated. Also, because the existing theory cannot give a detailed and reasonable explanation for the mechanism of recombination reaction, we can not accurately calculate how much Zn and/or Cd ions are added, which can control the occurrence of liquid mercury. The recombination reaction proceeds to the left.
  • the present invention adds a minimum amount of Zn and/or Cd and/or Pb ions as long as the purpose is to measure according to the principle of the anodic stripping voltammetry enrichment reaction and the dissolution reaction measurement of the present invention, and even a small amount is added to the sample to be tested.
  • the amount for example, the mass concentration of the Zn ion solution is 1 ⁇ 10 -15 %; the concentration of the Cd ion solution is 1 ⁇ 10 -15 %, which also infringes the present invention.
  • the Zn ion reagent is a ZnCl reagent, but a reagent containing a Zn ion such as ZnNO 3 or Zn 2 SO 4 may be used.
  • the Cd ion reagent is replaced by a Cd standard solution, but a Cd ion-containing reagent such as CdCl 2 or CdSO 4 can also be used.
  • the analysis conditions of the present invention are reagents in which Zn and/or Cd and/or Pb ions are added to the sample to be tested, and each metal mercury is recombined due to the recombination reaction occurring in liquid mercury.
  • Analytical conditions of the invention are reagents including, but not limited to, Zn and/or Cd and/or Pb ions.
  • the washing of the present invention uses Pb as a reference to realize electrolysis.
  • Pb washing in the pool and liquid mercury because the measured elution washing method of the present invention can not only use Pb as a reference, but also can realize Pb washing in the electrolytic cell and liquid mercury, and can also refer to metals such as Cd, Cu, In, etc.
  • washing of Cd, Cu, In and the like in the electrolytic cell and the liquid mercury is realized, but the washing and washing method of the present invention is used to realize the washing of the metals such as Cd, Cu, In and the like in the electrolytic cell and the liquid mercury.
  • the washing and washing method of the present invention is used to realize the washing of the metals such as Cd, Cu, In and the like in the electrolytic cell and the liquid mercury.
  • the metals which can be measured by the above analysis conditions of the present invention are Cd, Pb, Cu and In. Due to the recombination reaction occurring in liquid mercury, the metal amalgam and the metal-to-metal reaction among the intermetallic compounds, the reaction mechanism is very complicated, and the existing theory cannot give detailed details on the recombination reaction mechanism. The reason for the reasonable explanation, we can not infer whether there are other metal ions, can also be measured by the analytical conditions of the present invention, if there are other metal ions, can also be anodic stripping voltammetric enrichment reaction and dissolution according to the present invention The measurement of the principle of the reaction measurement is also within the scope of the invention. Thus the scope of protection (metal) of the present invention includes, but is not limited to, Cd, Pb, Cu, and In.
  • the analysis method of the present invention not only has the ability to accurately measure the quantitative detection capability of ⁇ g/l grade Pb, but also has the ability to accurately measure ng/L grade Pb, so the analysis method of the present invention can not only As an analytical method for measuring ⁇ g/L Pb in seawater or freshwater samples, it can also be used as an analytical method for ng/L grade Pb, and as an analytical method for measuring Pb in complex samples of soil, sediment, food, etc. It can also be used as an analytical method for measuring Cd, Cu and In in the above samples, and therefore the measurement of the above methods is within the scope of the present invention.

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Abstract

一种改进的电化学分析方法，是关于(洁净的)海水或淡水中的Pb是μg/L级，还是ng/L级的分析方法，包括改进的阳极溶出伏安分析方法和改进的电位溶出法分析方法，改进的电化学分析方法中富集反应为即富集到液态汞中的Zn、Cd、Pb和Cu汞齐，会与富集到液态汞中的干扰汞齐重新结合反应。提供了一种比电感耦合等离子体质谱法(ICP-MS)定量检出海水或淡水中的Pb浓度更低，更准确的分析方法，一种比现有的阳极溶出伏安法富集反应与溶出反应的测量原理，测量的海水或淡水样品中的Cd、Pb和Cu定量检出的浓度更低，更准确的分析方法。

Description

一种改进的电化学分析方法及应用 技术领域
本发明属于重金属检测技术领域，特别涉及一种改进的电化学分析方法及应用。
背景技术
作为分析方法分为非标准的分析方法和标准的分析方法两种。非标准的分析方法通常没有经过国家有关部门的专家科学的认证，比如由许昆灿等编《海洋污染物分析方法》中关于阳极溶出伏安法测量海水样品中Cd、Pb和Cu的分析方法，非标准的分析方法具有可比性较差，不具权威性等缺点。标准分析方法是经过国家有关部门的专家科学的验证的分析方法，比如国标GB 17378.4-2007《海洋监测规范》中，测量海水中的Pb等，标准分析方法具有较好的可比性、准确性和权威性，只有标准分析方法可在环境监测和执法中应用。
我国虽然采用标准的分析方法对海水或淡水样品中重金属的监测或测量有几十年的历史，但是现有的标准分析方法唯独测量海水样品及淡水样品中的Pb，常常发生再现性差现象，这也是国内外几十年没有解决的世界性难题。在过去的几十年我国测量(洁净)海水或淡水中的Pb，主要采用了以下的三种标准分析方法：
1)20世纪7-80年代，我国主要采用极谱仪作为分析仪器，对应的分析方法是阳极溶出伏安法，在《水和废水监测分析方法》(第四版)中，阳极溶出伏安法测量淡水中的Pb，在300S的富集时间条件下，检测下限可达0.5μg/L，即定量检出浓度为0.5μg/L。在国标GB 17378.4-2007《海洋监测规范》中，阳极溶出伏安法测量海水中的Pb检出限0.3μg/L，即Pb定量检出浓度为3μg/L，需要指出的是检出限是指定性检出浓度，若换算成定量检出浓度两者差一个数量级。从技术指标可以看出，阳极溶出伏安法属于一种具备μg/L级定量检出能力的分析方法，优点：样品不需要处理，可以直接测量的海水或淡水中的Zn、Cd、Pb和Cu；缺点：再现性差。
2)由于阳极溶出伏安法存在再现性差的的原因，20世纪90年代后，我国逐步淘汰了极谱仪，采用更先进无火焰原子吸收分光光度仪或称为石墨炉原子吸收分光光度仪作为分析仪器，对应的分析方法是无火焰原子吸收分光光度法，在国标GB/T5750.6-2006中，无火焰原子吸收分光光度法测量淡水中Pb的最低检测质量浓度为2.5μg/L，即定量检出浓度为2.5μg/L。在国标GB 17378.4-2007《海洋监测规范》中，无火焰原子吸收分光光度法测量海水中的Pb检出限0.03μg/L，即Pb定量检出浓度为0.3μg/L，从技术指标可以看出，无火焰原子吸收分光光度法同样属于一种具备μg/L级定量检出能力的分析方法，优点： 测量淡水样品中的Cd、Pb和Cu，样品不需要处理，可以直接测量，测量的过程简单快速。缺点；唯独测量海水样品或淡水样品中的Pb，常常发生再现性差现象。
3)电感耦合等离子体质谱法(ICP-MS)，是目前国内外专家公认的最权威的重金属标准分析方法，在HY/T147.1-2003《海洋监测技术规程》中，海水中Pb检出限为0.07μg/L，即定量检出浓度仅为0.7μg/L，该技术指标比无火焰原子吸收分光光度法定量检出浓度0.3μg/L略低。在国标GB/T5750.6-2006中，ICP-MS测量淡水中Pb，最低检测质量浓度为0.07μg/L，即定量检出浓度为0.07μg/L。缺点是：相对昂贵，成本很高，是一种高端分析仪器。
另外，由于目前国内外的专家普遍认为海水或淡水样品中的Pb是μg/L级的原因，因此普遍认为无火焰原子吸收分光光度法就可满足测量海水或淡水样品中μg/L级Pb的技术要求，但无火焰原子吸收分光光度法是一种从样品的处理、洗涤到测量均建立在海水或淡水中Pb是μg/L级定量检出能力的基础上的分析方法，因此积累了几十年的μg/L级Pb的海水或淡水原始数据。
以上现有的标准分析方法唯独测量海水或淡水样品中的Pb，常常发生再现性差的现象，本领域技术人员可知，任何分析方法，如果测量结果准确，理论上不会发生再现性差的现象，反之，如果存在再现性差的现象，理论上测量的结果不准确，由此推断现有的标准分析方法测量海水或淡水样品中的Pb，可能存在不准确的问题。
发明内容
本发明目的是解决现有的标准分析方法中测量海水或淡水样品中的Pb不准确的问题，提供一种从样品的处理、洗涤到测量均建立在ng/L级定量检出能力基础上的分析方法。
一种改进的电化学分析方法，采用阳极溶出伏安分析方法，是依据如下反应式实现的：富集反应：
Figure PCTCN2017070944-appb-000001
溶出反应：Rn++ne(+Hg)←R(Hg)。
采用电位溶出法分析方法，是依据如下反应式实现的：
富集反应：
Figure PCTCN2017070944-appb-000002
溶出反应：R(Hg)+1/2O2+2H+→Rn++Hg+H2O。
具体步骤如下：1)采集样品，进行样品处理，得到酸性的、含有电解质的待测样品，使得被测样品中的金属以离子的形式存在并且能够导电；2)洗涤电解池及液态汞；3)向待测样品中加入Zn和/或Cd离子溶液，然后采用极谱仪进行测量。
与现有技术相比，本发明通过实验结果及理论分析，得到了一种改进的电化学分析 方法，并对该方法中的样品采集方法、样品处理方法、电解池洗涤方法及测量方法进行了优化，解决现有技术中测量洁净的海水或淡水样品中Pb不准确的难题。
附图说明
图1-12实验1-12中的溶出谱图。
具体实施方式
本发明中讨论的海水是指岸边、近海和远海的海水，不包括排污口的海水；淡水是指没有受到污染的或污染较轻的引用水源地、江、河流、地下水等含盐量低的淡水样品，不包括排污口的淡水。
为了以下的讨论方便，我们将浓度低于0.03μg/L的Pb，称为ng/L级的Pb，将浓度范围在0.3-2.5μg/L的Pb，称为μg/L级的Pb。目前国内外专家普遍认为海水或淡水样品中的Pb是μg/L级，在1983年人民卫生出版社出版发行(日)山県登著《微量元素》中：Patterson提出，河水中铅浓度为1-5ppb是偏高的，这是因为样品制备过程中有污染。若在清洁实验室仔细分析，真实的数据为雪中0.5ppb，而河水中大约0.015ppb。至于海水中的含铅量，在1930-1950年之间已进行了大量分析，结果为2-5ppb，而最近采用0.03ppb相当低的数值(Tatsumoto和Patterson)，即海水或河水中的Pb是ng/L级。假设海水或河水中的Pb是ng/L级的观点成立，而现有技术是采用一种从样品的处理、洗涤、到测量仅具备μg/L级定量检出能力的标准分析方法，假如我们采用一种从样品的处理、洗涤、到测量仅具备μg/L级定量检出能力的标准分析方法，去测量ng/L级的海水或淡水样品中的Pb，理论上测量的结果也不准确，再现性差可能与此有关。因此研究一种从样品的处理、洗涤、到测量，均建立在海水或淡水样品中的Pb是ng/L级基础上的分析方法，去验证海水或河水中的Pb是ng/L级观点是否成立或正确。这将对国内外的专家正确的认识海水或淡水中的Pb浓度、以及更准确的测量海水或淡水样品中的Pb具有非常重要的意义。
由于现有的标准分析方法测量海水或淡水样品中的Cd、Pb、Cu，唯独测量Pb存在再现性差不准确的问题，还有Tatsumoto和Patterson也认为海水或淡水样品中的Pb是ng/L级，因此本发明的重点是解决现有的标准分析方法唯独测量海水或淡水样品中Pb存在的再现性差不准确的问题，仅对测量海水或淡水中的Pb进行详细的讨论，在涉及到Cd和Cu时做适当的讨论，但测量Cd和Cu也在本发明分析方法的保护范围，特此说明。
关于分析方法的选择：
我们知道阳极溶出伏安法是一种检出的溶出峰峰高与富集时间有关的电化学分析方法，在《水和废水监测分析方法》(第四版)中，阳极溶出伏安法又称为反向溶出伏安法，其基本过程分为两步：先将待测金属离子在比其峰电位更负一些的恒电压下，在工作电极上预电解一定时间使之富集。然后，将电位由负向正的方向扫描，使富集在电极上的物质氧化溶出，并记录其氧化波。根据溶出峰电位确定被测物质的成分，根据氧化波的高度确定被测物质的含量。其全过程可表示为：
Figure PCTCN2017070944-appb-000003
其中，Mn+代表金属离子，包括但不限于Zn、Cd、Pb和Cu离子。
电解还原是缓慢的富集，溶出是突然的释放，因而作为信号的法拉第电流大大增加，从而使方法的灵敏度大为提高。如果现有的阳极溶出伏安法能严格按照，在进行富集反应时，能将被测样品中的Zn、Cd、Pb、Cu、Sn、Te、Bi、Ni、Ga、In、Ti和Co等金属离子，富集到银基汞膜工作电极液态汞(本发明中可将“银基汞膜工作电极液态汞”简称为“液态汞”)中生成Zn、Cd、Pb、Cu、Sn、Te、Bi、Ni、Ga、In、Ti和Co汞齐，在进行溶出反应时，不仅能测量出Zn、Cd、Pb和Cu的溶出峰，理论上还应该可以测量出Sn、Te、Bi、Ni、Ga、In、Ti和Co等金属的溶出峰。且富集时间越长，被测样品中的能被富集的Zn、Cd、Pb和Cu离子的比例越高，液态汞中生成Zn、Cd、Pb和Cu汞齐的浓度就越高，因此理论上只要富集的时间足够长，不仅能测量出海水或淡水样品中μg/L级的Pb溶出峰，还应该能测量出ng/L级Pb的溶出峰，甚至能测量出比ng/L级Pb更低浓度的Pb溶出峰，因此本发明选用阳极溶出伏安法。
如果将现有的阳极溶出伏安法反应全过程分开表示，又可表示为：
富集反应；Mn++ne(+Hg)→M(Hg)
与溶出反应；M n++ne(+Hg)←M(Hg)。
还有一种分析方法电位溶出法与现有的阳极溶出伏安法的富集反应完全相同，电位溶出法是在现有的阳极溶出伏安法的基础上演变来的，这导致具有相同的富集反应。电位溶出法总反应式为：Hg2++2e→Hg
富集反应：Mn++ne(+Hg)→M(Hg)
溶出反应：M(Hg)+1/2O2+2H+→M2++Hg+H2O
以上可以看出，现有的电位溶出法与现有的阳极溶出伏安法的富集反应完全相同，从电位溶出法的富集反应与溶出反应可以看出，电位溶出法也是一种检出的浓度与富集时间有关的分析方法，假如电位溶出法的测量原理正确，同样只要富集的时间足够长，不仅 能测量出海水或淡水样品中μg/L级的Pb溶出峰，还能测量出ng/L级Pb的溶出峰，甚至能测量出比ng/L级Pb更低浓度的Pb溶出峰。需要说明的是，本发明仅以阳极溶出伏安法为例进行实验与详细的讨论，通过阳极溶出伏安法推出正确的结论，来推断出正确的电位溶出法的富集反应与溶出反应，特此说明。
为了以下的叙述方便，在本发明中“现有的的分析方法”是指：采用现有的阳极溶出伏安法，测量的原理是现有的阳极溶出伏安法富集反应与溶出反应，现有的分析条件是指1)分析样品的底液是酸性，目的是使被测样品的金属以离子的形式存在；2)被测海水样品及淡水样品中必须含有一定量的电解质，因此淡水样品中通常再加入一定量的电解质，目的是使分析样品的底液导电；以满足现有的阳极溶出伏安法富集反应与溶出反应的正常进行。
为了以下的叙述方便，在本发明中Zn、Cd、Pb和Cu离子简称为目标离子，Zn、Cd、Pb和Cu汞齐简称为目标离子汞齐；被测样品中除了Zn、Cd、Pb和Cu以外的其它金属离子，例如Sn、Te、Bi、Ni、Ga、In、Ti和Co等简称为干扰金属离子；Sn(Hg)、Te(Hg)、Bi(Hg)、Ni(Hg)、Ga(Hg)、In(Hg)、Ti(Hg)等金属汞齐简称为干扰汞齐。
样品的采集与处理：采集ng/L级Pb的海水或河水样品，应选择没有受到污染的海水或淡水样品，较为理想的海水样品，理论上应该选择远海海水，由于采集远海海水会受到很多因素(船)的限制，本发明实验用海水样品，选择了青岛市市南区银海大世界岸边的海水；本发明实验用淡水样品，选择了青岛崂山北九水风景区上游的河水。
盛放样品的容器：由于目前国内外还没有关于洗涤ng/L级Pb器皿的洗涤方法，经实验测量采用正规厂家生产的优质矿泉水的Pb浓度很低，比较接近ng/L级(Pb)，因此对矿泉水瓶进行洗涤处理后可满足盛放ng/L级Pb样品的要求，洗涤方法是在采集的ng/L级样品中加入适量的酸对矿泉水瓶洗涤数次；本发明中盛放ng/L级样品的器皿均采用该方法洗涤后的矿泉水瓶，以下不再进行单独的解释。
由于本实验是一种涉及测量ng/L级Pb的分析方法，因此样品的处理必须按照ng/L级(Pb)处理，而目前国内外普遍采用样品通过孔径0.45μm的滤膜过滤后再加酸酸化的样品处理方法，虽然过滤可以防止样品中悬浮的颗粒和生物体导致测量结果的偏高，加酸酸化也可以防止吸附现象发生。但这是一种将海水或淡水中Pb，建立在μg/L基础上的样品处理方法。由于目前国内外还没有关于洗涤ng/L级Pb的洗涤方法或技术，现有的洗涤方法理论上将过滤器皿或滤膜洗涤干净(至ng/L级Pb)的可能性很小，假如采用孔径0.45μm的滤膜过滤后再加酸酸化的样品处理方法，理论上会导致ng/L级样品的沾污，使测量的结果偏高。 因此采用孔径0.45μm的滤膜过滤后再加酸酸化的样品处理方法，建议不要采用。从技术的角度分析，处理ng/L级(Pb)的样品，如果样品处理发生沾污，通常带来不是30％或50％的偏高，很可能是成数量级的偏高。但是如果样品处理发生吸附现象，通常有可能带来30％或50％的偏低，但发生成数量级的偏低的可能性很小，因此虽然沾污和吸附都会带来测量误差，但是吸附带来的误差理论上可能更小，更接近真值。因此关于处理ng/L级样品，建议尽量选择能避免发生沾污现象的样品处理方法，1)不过滤不加酸，将采集的样品直接置于样品瓶中，将样品静置3-12h，利用静置最大限度的降低悬浮颗粒和生物对测量结果的影响，测量时取上清液测量。优点是没有沾污，缺点是仅适合于非常清澈的海水或淡水样品当天测量使用；无法消除样品中悬浮的颗粒和生物对测量结果偏高的影响；不易长期保存，因为样品不加酸理论上会发生吸附现象，导致测量的结果偏低。2)不过滤不加酸静置后再加酸，对采集的样品静置6-36h，时间过长易发生吸附现象，导致测量结果偏低，因此建议6-36h。具体操作过程是将静置后的样品的上清液导入另一个样品瓶中，加适量的酸对样品酸化保存，优点是没有沾污，通过静置的方法最大限度的降低样品中悬浮颗粒对测量结果的影响，可实现样品较长时间的保存，但是无法完全消除样品中悬浮的颗粒和生物体对测量结果的影响，适合于较为清澈的样品处理。3)不过滤加酸，对采集的样品不静置，加适量的酸对样品酸化保存，优点是没有沾污，不会发生吸附现象。缺点，仅适合特殊的地点、特殊的采样时间等严格的限定采集的非常清澈的样品处理，理论上无法完全消除样品中悬浮的颗粒和生物对测量结果偏高的影响。4)对样品离心处理，适用于当天采集的较为浑浊的样品，方法是用离心机专用的器皿离心处理，取上清液，转移到另一个样品瓶中，再加适量的酸酸化样品。优点可以快速最大限度的降低样品中悬浮颗粒，防止吸附现象发生。缺点对离心机专用器皿的洗涤工作量非常大，优选将离心机专用器皿改用上述矿泉水瓶。5)吸附样品处理法，适用于不能对当天采集的样品进行离心处理的样品，方法是采用两个或多个容器采集样品，优选采用经洗涤处理的矿泉水瓶，静置12h以上，理论上每个容器都会发生吸附现象，样品中的悬浮颗粒会自然沉降，扰动其中一个容器A并倒掉样品，目的将沉淀于容器底部的悬浮颗粒随样品一起倒出，得到一个已经发生吸附现象的空容器，将其它容器中同样已经发生吸附现象的样品的上清液B转移到容器A中，再加入适量的酸酸化样品，吸附到容器A内壁的Pb就会重新溶于上清液B中，该方法可以最大限度的降低吸附现象产生的影响，使样品中的Pb浓度最大限度的接近样品的真值。通过对上述几种样品处理方法的讨论，每种样品处理方法都有优缺点，这需要我们根据采集样品的实际情况选择适合的样品处理方法处理ng/l级Pb样品。
为了证明海水样品中的Pb是ng/L级，本发明采用方法3)不过滤加酸的样品处理方法，这种不过滤加酸的样品处理方法对采集样品的天气、采集样品时间和采集样品的地点进行了限定：采集海水样品的天气，通常选择风力较小，海水清澈，天气晴朗的天气；采集样品的时间，选择海水低潮后一小时左右后采集；采集样品的地点，选择尽量远离岸边较大的凹型礁石中残存的较大水体中的海水，这种残存在较大的凹型礁石中较大水体的海水样品，是经过数小时的自然沉淀，样品中悬浮颗粒被最大限度的减少，因此可以最大限度的减少悬浮颗粒对测量结果的影响。对采集的海水样品，立即加适量的1:2硝酸酸化至pH＝3-4或pH＝4-5的两种不同的酸度的样品，以防止发生吸附现象发生，防止测量结果的偏低。对采集的淡水样品，通常选择风力较小，天气晴朗的天气，选择了青岛崂山北九水风景区上游的河水，采集后，加适量的1:2硝酸酸化至pH＝3-4或pH＝4-5的两种不同酸度的样品。上述方法采集的海水、河水相当于静置后的样品，再经硝酸酸化处理后作为待测样品，以下分别称为洁净的海水、洁净的淡水。
关于实验室的环境：本发明虽然是测量ng/L级的Pb，但是本发明对样品的采集及处理和测量过程进行了优化，因此可以不在100级超净的实验室环境下完成，在普通的相对密闭的实验室环境下即可完成测量。在普通的相对密闭的实验室环境下即可完成测量，这在分析技术上也是一项非常大的突破，将对该分析方法的推广，具有非常重要的意义。
关于实验的仪器：为了满足本发明的实验对分析仪器的灵敏度和稳定性的要求，本发明采用由青岛极谱仪器有限公司生产的进行防尘处理的多功能极谱仪，极谱仪的工作电极采用银基汞膜电极，参比电极采用银氯化银参比电极或甘汞参比电极，辅助电极采用铂电极。
仪器主要参数设置(以下称为仪器默认参数)：灵敏度为12，清洗时间QT＝60秒，富集反应时间FT＝360s，静置时间JT＝6s，扫描时间ST＝6s；富集电压为负1.2V，起始电压为负1.3V，扫描终止电压为负0.05V。
关于试剂：Pb标准溶液，1000ug/ml，GSB G 62071-90；Cd标准溶液，1000ug/ml，GSB G 62040-90；Cu标准溶液，1000ug/ml，GSB G 62024-90；In标准溶液，1000ug/ml，GSB G 04-1731-2004；所用的标准使用溶液，是由上述母液稀释后获得。1:2硝酸溶液是1体积的硝酸和2体积的水混合。5％氯化锌溶液是取5.0g氯化锌溶于100ml超纯水中；0.1％氯化锌溶液是取2ml5％氯化锌溶液，稀释至100ml，配制成0.1％氯化锌溶液。
实验1
实验目的：通过测量海水样品中的Cd、Pb和Cu的全过程，了解阳极溶出伏安法是 如何对海水或淡水样品中的Cd、Pb和Cu进行定性和定量的。
采用现有的对电解池的洗涤方法，是取酸性的超纯水通过搅拌的方式对电解池进行多次洗涤，干净后，取pH＝4-5的酸性洁净的海水样品20ml于电解池中。由于洁净海水样品中Zn、Cd、Pb和Cu离子的浓度很低，在被测样品中加入浓度为10mg/l的Zn标准溶液大约30μL，浓度为0.4mg/l的Cd标准溶液大约20μL，浓度为1mg/l的Pb标准溶液大约20μL，浓度为3mg/l的Cu标准溶液大约20μL，加入大约量Zn、Cd、Pb和Cu标准溶液的目的，是为了提高样品中Zn、Cd、Pb和Cu离子的浓度，观测到更为明显的Zn、Cd、Pb和Cu溶出峰。按仪器默认的参数设置，富集时间修改为30秒，首先进行富集反应，将被测样品中的Zn、Cd、Pb和Cu离子富集到液态汞中还原，生成Zn(Hg)、Cd(Hg)、Pb(Hg)、Cu(Hg)汞齐，简称为Zn、Cd、Pb和Cu汞齐。再进行溶出反应，电位由负向正的方向扫描，使富集在电极上的物质氧化溶出，并记录其氧化波即溶出谱图，见溶出谱图1-1。
从溶出谱图1-1可以看出，有Zn、Cd、Pb和Cu的溶出峰，因此如果液态汞中有Zn、Cd、Pb和Cu汞齐存在，在溶出反应时就能测量出Zn、Cd、Pb和Cu的溶出峰。阳极溶出伏安法对金属离子的定性是根据溶出峰电位，确定被测物质的成分，不同的元素溶出峰电位不同，Zn溶出峰电位通常在-0.9V左右，Cd溶出峰电位通常在-0.6V左右，Pb溶出峰电位通常在-0.4V左右，Cu溶出峰电位通常在-0.2V左右，不同的介质的样品，溶出峰的电位会左右略微变化。阳极溶出伏安法是通过溶出谱图计算浓度的分析方法，是先测量被测样品的溶出谱图，见溶出谱图1-1，连续测量数次，待测量的峰高稳定重复，加标前通常取最后测量的两次稳定重复的溶出峰峰高，测量最后的两次Cd溶出峰峰高分别为13.38和13.70，测量最后的两次Pb溶出峰峰高分别为2.52和3.13，测量最后的两次Cu溶出峰峰高分别为22.61和23.49。再在被测样品中加入适量的Cd、Pb和Cu的混合标准溶液，继续测量，扫描溶出，见溶出谱图1-2。加入三种不同浓度的Cd、Pb和Cu混合标准溶液后，Cd、Pb和Cu的溶出峰峰高明显增高，加标后通常取两次稳定重复的加标后峰高，测量Cd溶出峰峰高分别为29.96和29.67，测量Pb溶出峰峰高分别为12.11和11.53，测量Cu溶出峰峰高分别为47.52和46.98。再根据阳极溶出伏安法计算浓度的公式就可以分别计算出Cd、Pb和Cu的浓度。
通过以上的实验，证明了现有的阳极溶出伏安法是可以同时对Cd、Pb和Cu测量，由于本发明是在现有的阳极溶出伏安法的基础上进行改进的，因此同样具备对Cd、Pb和Cu进行测量的能力，这样以下的实验不再对本发明的Cd、Pb和Cu的同时测量进行单独 的实验验证，特此说明。
需要说明的是，1)从测量的溶出谱图1-1和1-2可以看出，横坐标是电压，单位是伏(V)，纵坐标是峰电流，用峰高值表示，由于以下的溶出谱图与图1或图2的横坐标与纵坐标的表示方法完全相同，因此在以下的溶出谱图中不再详细的标识横坐标与纵坐标，2)在图1中对两条重复谱图进行了重复显示，当很多谱图重复显示时，不易准确表达要表达的谱图，因此在其它的谱图显示中，仅对重复的谱图中的一条谱图进行显示，特此说明。
以上，阳极溶出伏安法采用现有的分析条件，能测量出稳定重复的Cd、Pb和Cu的溶出峰，延长富集时间，测量的Cd、Pb和Cu的溶出峰也能增高。因此如果现有的阳极溶出伏安法的测量原理正确，只要富集时间足够长，理论上讲能测量出ng/L级Pb的溶出峰，下面通过实验2进行实验验证，阳极溶出伏安法采用现有分析方法的分析条件，对能否测量出洁净的海水中的Pb溶出峰进行实验。
实验2
电解池的洗涤方法、洁净的海水样品的取液量、分析条件、仪器参数设置均与实验1相同，富集360s，得到溶出谱图2-1。延长富集时间至999秒，其它操作条件不变，得到溶出谱图2-2。实验的结果表明，延长富集时间，也不能测量出Pb溶出峰，由此证明现有的阳极溶出伏安法不是一种检出的溶出峰峰高与富集时间有关的电化学分析方法，这种现象用现有的阳极溶出伏安法富集反应与溶出反应的测量原理无法给出合理的解释。
实验3
由于海水样品介质复杂，干扰多，可能会对测量结果产生影响。实验3中采用洁净的淡水进行实验验证，电解池的洗涤方法、取样品的量、分析条件、仪器参数设置均与实验1相同，电解池中，加8滴饱和KCl溶液以增加电解质，富集360秒，得到溶出谱图3-1。延长富集时间至999秒，其它操作条件不变，得到溶出谱图3-2。实验的结果表明，延长富集时间，同样不能测量出Pb溶出峰，由此再次证明现有的阳极溶出伏安法不是一种检出的溶出峰峰高与富集时间有关的电化学分析方法，再次说明现有的阳极溶出伏安法富集反应与溶出反应的测量原理存在问题。
以上实验结果表明，阳极溶出伏安法采用现有的分析条件，不能测量出洁净的海水或淡水样品的Pb溶出峰，导致不能实现对洁净的海水或淡水样品中Pb的浓度进行测量。这是因为：在进行富集反应时，不仅被测样品中的Zn、Cd、Pb和Cu离子可以富集到液态汞中还原，生成Zn、Cd、Pb和Cu汞齐，被测样品中除了Zn、Cd、Pb和Cu以外的干扰金属离 子也可以富集到液态汞中还原，生成干扰汞齐。同样的，在进行溶出反应时，不仅Zn、Cd、Pb和Cu汞齐能形成Zn、Cd、Pb和Cu的溶出峰，理论上讲干扰汞齐也能形成干扰金属的溶出峰。但是在实际测量中，通常我们只能测量出Zn、Cd、Pb和Cu的溶出峰，不能测量出干扰金属的溶出峰，为什么不能测量出干扰汞齐溶出峰？根据现有的溶出反应测量原理，要想测量出Zn、Cd、Pb和Cu的溶出峰，液态汞中必须有Zn、Cd、Pb和Cu汞齐存在，同样的道理，如果液态汞中有干扰汞齐存在，在进行溶出反应时就能测量出干扰金属的溶出峰。由此推断，富集到液态汞中的干扰汞齐，在进行溶出反应之前，有可能已经发生了新的化学反应，生成了新的物质。假如我们将富集到液态汞中按照能形成溶出峰和不能形成溶出峰分开表示，现有的阳极溶出伏安法的富集反应又可以表示为；
Rn++Nn++ne(+Hg)→R(Hg)+N(Hg)
富集到液态汞中的Zn、Cd、Pb和Cu汞齐，有可能会与富集到液态汞中的干扰汞齐重新结合反应，其反应可表示为：
Figure PCTCN2017070944-appb-000004
其中：Rn+-表示能够形成溶出峰的金属离子，包括但不限于Zn、Cd、Pb和Cu离子，即目标离子；Nn+-表示不能形成溶出峰的金属离子，即干扰金属离子；R(Hg)–表示能够形成溶出峰的金属汞齐，包括但不限于Zn、Cd、Pb和Cu汞齐，即目标汞齐；N(Hg)–表示不能形成溶出峰的金属汞齐，即干扰汞齐；RN-表示金属间化合物。
以下我们将上述反应称为“重新结合反应”。在1984年5月四川科学技术出版社出版发行汪尔康等编著《示波极谱及其应用》中提到在电解富集过程中有几种金属同时进入汞中时，金属与金属间有可能形成金属间化合物，也像金属离子与阴离子在水溶液中有一个溶度积相似，如表1是某些金属间化合物在汞中的溶度积。
表1某些金属间化合物在汞中的溶度积
化合物 溶度积 温度(℃) 化合物 溶度积 温度(℃)
ZnAu (2.5±0.5)×10-12 90 SnNi (1.4±0.9)×10-12 20
CdAu (2.5+0.4)×10-9 90 SnSb (2.6±0.6)×10-9 18
InAu (1.9±0.7)×10-6 18 ZnCu (5±1)×10-8 25
ZnAg (2.7±0.5)×10-6 18 NiGa 3.9×10-16 20
CoAg (7.3±0.9)×10-6 18 CoGa 2.6×10-16 20
Cd3Mn (6.7±0.5)×10-11 20 CuGa 2×10-6 20
Sn2Mn (7.1±0.6)×10-9 20 CuGe3 8.3×10-13 20
CdAg 7×10-6 20 CuSb 3.7×10-7 20
SnCu (4.6±0.9)×10-6 20 SbCd 1×10-8 20
SnCu3 (2.8±1.3)×10-12 20 SbIn 2×10-8 20
按照汪尔康等专家的观点，富集到液态汞中的Zn、Cd、Pb和Cu汞齐会与富集到液态汞中的干扰汞齐有可能重新结合反应，生成例如表1中的金属间化合物。
实验4
验证液态汞中是否有可能发生重新结合反应实验。实验4是在实验2中的溶出谱图2-2的基础上继续进行的，仪器参数的设置与溶出谱图2-2的仪器参数完全相同。根据现有的阳极溶出伏安法富集反应与溶出反应的测量原理，不能测量出Pb溶出峰、Cd溶出峰、还有干扰金属的溶出峰，是因为液态汞中没有Pb汞齐、Cd汞齐、干扰汞齐存在。为什么延长了富集时间，液态汞中没有Pb汞齐、Cd汞齐、干扰汞齐存在有两种可能，一种是富集时间不够，导致富集到液态汞中的Pb汞齐的浓度太低；另一种是富集到液态汞中的Pb汞齐，在进行溶出反应之前发生了重新结合反应，生成了与Pb有关的金属间化合物。
假如重新结合反应的观点成立，不能测量出Pb溶出峰可以解释为，在进行富集反应后，液态汞中的Pb、Cd、Zn和Cu汞齐，与液态汞中的干扰金属汞齐会重新结合反应，富集到液态汞中Pb汞齐、Cd汞齐中的Pb、Cd，全部不再与汞重新结合，而是与除了汞以外的金属结合，生成了与Pb和Cd有关的金属间化合物残存在液态汞中；同时富集到液态汞中干扰汞齐中的干扰金属，也是全部不能再与汞重新结合，也是与除了汞以外的金属结合，生成了与干扰金属有关的金属间化合物；而富集到液态汞中Cu汞齐中的Cu，还能与汞重新结合，生成Cu汞齐，这将导致在进行溶出反应时，只有Cu汞齐，没有Pb汞齐、Cd汞齐、干扰金属汞齐存在的现象发生，就会发生只能测量出Cu溶出峰，不能测量出Pb溶出峰、Cd溶出峰、干扰金属溶出峰的现象。当反复测量被测样品时，在进行富集反应后，富集到液态汞中的Zn、Cd、Pb和Cu汞齐、干扰汞齐、及液态汞中残存一定浓度的与Pb、Cd有关的金属间化合物和与干扰金属有关的金属间化合物会继续重新结合反应，残存在液态汞中与Pb和Cd有关的金属间化合物中Pb和Cd，还是不与汞重新结合，继续生成与Pb和Cd有关的金属间化合物；富集到液态汞中Pb汞齐、Cd汞齐中的Pb、Cd，还是全部不再与汞重新结合，而是与除了汞以外的金属结合，生成了与Pb和Cd有关的金属间化合物，液态汞中的与Pb和Cd金属有关的金属间化合物的浓度继续增加；同时富集到液态汞中干扰汞齐中的干扰金属，也还是全部不能再与汞重新结合，还是与除 了汞以外的金属结合，生成了与干扰金属有关的金属间化合物，液态汞中与干扰金属有关的金属间化合物的浓度也继续增加；而富集到液态汞中Cu汞齐中的Cu，还能继续与汞重新结合，生成Cu汞齐，在进行溶出反应时，还是只有Cu汞齐，没有Pb汞齐、Cd汞齐、干扰金属汞齐存在，因此还是只能测量出Cu溶出峰，不能测量出Pb溶出峰、Cd溶出峰、干扰金属溶出峰。
虽然不能测量出Pb和Cd溶出峰，但是理论上讲液态汞中已经残存了一定浓度的与Pb有关的金属间化合物，如果我们能够找到一种特殊的分析条件，这也是本发明分析条件中的一种，目的控制重新结合反应向左进行，将残存在液态汞中的与Pb有关的金属间化合物中的Pb重新转化为Pb汞齐，在进行溶出反应时，理论上就能测量出Pb溶出峰。本发明采用的特殊分析条件是，在被测的样品中加入质量浓度为0.1％的ZnCl 20μL，继续测量洁净的海水样品，扫描溶出，见溶出谱图4，能测量出Pb溶出峰、Cd溶出峰，但没有测量出干扰金属的溶出峰，满刻度的Zn溶出峰是在被测样品中加入ZnCl溶液造成的。
本发明在被测样品中加入较高浓度的Zn离子(唯一改变的条件)，使得被测样品中的Zn、Cd、Pb和Cu离子总的浓度大大的提高，富集到液态汞中Zn、Cd、Pb和Cu汞齐总的浓度将远远大于干扰汞齐和与干扰金属有关的金属间化合物中有关的汞齐或金属总的浓度。虽然富集到液态汞中的Zn、Cd、Pb和Cu汞齐、干扰汞齐、及液态汞中残存一定浓度的与Pb、Cd或干扰金属有关的金属间化合物，继续在液态汞中重新结合反应；富集到液态汞中Pb和Cd汞齐中的Pb和Cd，重新与汞结合，生成Pb和Cd汞齐存在于液态汞中，同时残存在液态汞中一定浓度的与Pb和Cd有关的金属间化合物中的Pb和Cd，也重新与汞结合，生成较高浓度Pb和Cd汞齐。同时残存在液态汞中一定浓度的与干扰金属有关的金属间化合物中的干扰金属，继续与除了汞以外的金属结合，继续生成与干扰金属有关的金属间化合物，同时富集到液态汞中干扰汞齐中的干扰金属，还是不能与汞重新结合，而是与除了汞以外的金属结合，生成了与干扰金属有关的金属间化合物，这导致液态汞中与干扰金属有关的金属间化合物的浓度继续增加，并且无法除去。在进行溶出反应时，由于液态汞中还是没有干扰汞齐存在，就会发生不能测量出干扰金属溶出峰的现象。由于富集到液态汞中的Pb汞齐、Cd汞齐、及残存在液态汞中一定浓度的与Pb有关的金属间化合物转化生成的Pb汞齐、一定浓度的与Cd有关的金属间化合物转化生成的Cd汞齐，就会测量出图4中较高的Pb溶出峰、较高的Cd溶出峰的现象。由于残存在液态汞中一定浓度的与Pb和Cd有关的金属间化合物也能转化生成Pb和Cd汞齐形成Pb和Cd溶出峰的原因，因此本发明分析条件测量的Pb溶出峰、Cd溶出峰，是不能作为计算洁净 的海水样品中的Pb浓度、Cd浓度的溶出峰，否则测量的结果严重偏高。但是能测量出洁净的海水样品中的Pb溶出峰，将对有可能实现较为准确的测量洁净的海水样品中的Pb具有非常重要的意义。阳极溶出伏安法采用现有的分析条件，由不能测量出洁净的海水样品中的Pb溶出峰，到采用本发明的分析条件，能测量出Pb溶出峰，这个实验的结果可以证明汪尔康等“金属间化合物”的观点是成立或正确，实验的结果也证明了液态汞中Zn、Cd、Pb和Cu汞齐会与干扰汞齐重新结合反应。经以上分析可以得出本发明的阳极溶出伏安法富集反应，是在现有的阳极溶出伏安法富集反应的基础上，再叠加重新结合反应得到的；溶出反应时，由于通常只有Zn、Cd、Pb和Cu汞齐能形成溶出峰，而干扰汞齐不能形成溶出峰。因此：
富集反应可表示为：
Figure PCTCN2017070944-appb-000005
溶出反应可以表示为：Rn++ne(+Hg)←R(Hg)。
同样的，本发明的电位溶出法的富集反应和溶出反应如下：
富集反应可表示为：
Figure PCTCN2017070944-appb-000006
溶出反应可以表示为：R(Hg)+1/2O2+2H+→R2++Hg+H2O。
本发明的阳极溶出伏安法富集反应与溶出反应、电位溶出法富集反应与溶出反应，将对指导我们正确的测量海水、淡水等样品中的Cd、Pb和Cu的浓度具有非常重要的意义。由于本发明阳极溶出伏安法的富集反应与本发明电位溶出法的富集反应完全相同，因此根据本发明的电位溶出法富集反应与溶出反应测量原理，再采用本发明的分析条件，测量Cd、Pb和Cu等金属也在本发明保护的范围内，特此说明。
需要补充，1、由于发生在液态汞中各金属汞齐以及各金属间化合物中的金属与金属之间的反应机理非常复杂，现有的理论无法解释也无法表达液态汞中各金属汞齐以及各金属间化合物中的金属与金属之间是如何反应结合的，因此发生在液态汞中的重新结合反应，只能是一种表达式，在准确的表达方面，不能准确的表达，也在情理之中。还有本发明的的阳极溶出伏安法富集反应，是在现有的阳极溶出伏安法富集反应的基础上，再叠加重新结合反应得到的，因此本发明的的阳极溶出伏安法富集反应与溶出反应、还有电位溶出法富集反应与溶出反应在准确的表达方面，可能存在表达上的缺陷，同样也在情理之中。
2、由于液态汞中存在重新结合反应的原因，阳极溶出伏安法实质上是一种将富集到液态汞中Pb等金属(等金属是指除了Pb，还可能是Cd或Cu或Zn)汞齐、干扰汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物、与干扰金属有关的金属间化合物之间重新结合反应之后，再进行溶出反应的测量方法。
实验4与实验2相比唯一改变的分析条件，是在被测的样品中加入了较高浓度的Zn离子，大量实验的结果证明，能否测量出洁净的海水或淡水样品中的Pb溶出峰，与被测样品中Zn、Cd和Pb离子的总浓度有关，与被测样品中Cu离子浓度的高或低无关或影响很小。由于能否测量出洁净的海水或淡水样品中的Pb溶出峰，与被测样品中Zn、Cd和Pb离子的总浓度有关，因此本发明是通过在被测样品中加入Zn和/或Cd和/或Pb离子的方式提高被测样品中Zn、Cd和Pb离子的总浓度，来实现测量出洁净的海水、淡水等样品中Pb等金属溶出峰的。
实验5
实验5是在实验3中的溶出谱图3-2的基础上继续进行的，在被测样品中加入浓度是2mg/l的Cd标准溶液30μL(这里选择了用Cd标准溶液代替含有Cd离子的试剂)，提高被测样品中Zn、Cd和Pb总的浓度，验证采用本发明的分析条件，在被测样品中加入Cd离子能否测量出Pb溶出峰？仪器参数的设置与图3-2的仪器参数完全相同，再次富集，扫描溶出，溶出谱图见图5，可以看出，能测量出满刻度的Cd溶出峰和较高Pb溶出峰，Cu溶出峰明显的增高，这种现象用本发明的阳极溶出伏安法富集反应与溶出反应测量原理可以给出合理的解释，同实验4。
实验5中Cu溶出峰明显增高，是因为采用现有的分析方法的分析条件，测量洁净淡水样品中的Cu，可以将被测样品中的Cu等金属(等金属是指除了Cu，还可能是Pb或Cd或Zn)离子富集到液态汞中生成Cu等金属汞齐，也可以将干扰金属离子富集到液态汞中生成干扰汞齐。由于洁净的淡水样品中的Zn、Cd和Pb离子总的浓度较低的原因，还有洁净的淡水样品中的Cu离子的浓度较低的原因，这导致液态汞中Zn、Cd和Pb汞齐总的浓度小于干扰汞齐以及与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度，富集到液态汞中生成Cu等金属汞齐和干扰汞齐，还有残存在液态汞中与干扰金属有关的金属间化合物，会在液态汞中重新结合反应，富集到液态汞中的Cu等金属汞齐中的Cu，按一定的比例(数)与汞重新结合，生成Cu汞齐，剩余部分的Cu与除了汞以外的金属结合，生成了与Cu有关的金属间化合物，这将导致液态汞中残存与Cu等金属有关的金属间化合物的现象发生；残存在液态汞中与干扰金属有关的金属间化合物中的干扰金属，还是与除了汞以外的金属结合，继续生成与干扰金属有关的金属间化合物；富集到液态汞中干扰汞齐中的干扰金属，与除了汞以外的金属结合，生成与干扰金属有关的金属间化合物，这将导致液态汞中与干扰金属有关的金属间化合物的浓度继续增加。需要说明的是，由于残存在液态汞中与干扰金属有关的金属间化合物中的干扰金属，具有始终与除了汞以 外的金属结合，继续生成与干扰金属有关的金属间化合物的特性，富集到液态汞中干扰汞齐中的干扰金属，也具有始终与除了汞以外的金属结合，生成与干扰金属有关的金属间化合物的特性，因此在以下的讨论中，不再对残存在液态汞中与干扰金属有关的金属间化合物，还有富集到液态汞中干扰汞齐关于重新结合反应进行讨论，特此说明。在进行溶出反应时，由于富集到液态汞中的Cu汞齐中的Cu，是部分的Cu与汞重新结合，生成的Cu汞齐，就会形成偏低的Cu溶出峰。就会发生能测量出Cu溶出峰的现象，但实际测量出的Cu溶出峰偏低。当再次或反复进行富集反应后，由于测量的洁净淡水样品中的Zn、Cd和Pb离子总的浓度没有变化，导致液态汞中Zn、Cd和Pb汞齐总的浓度，与液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度没有变化，富集到液态汞中生成Cu等金属汞齐和干扰汞齐，还有残存在液态汞中与Cu有关的金属间化合物和与干扰金属有关的金属间化合物，还会在液态汞中重新结合反应，残存在液态汞中与Cu有关的金属间化合物中的Cu，继续与除了汞以外的金属重新结合，继续生成与Cu有关的金属间化合物残存在液态汞中。富集到液态汞中的Cu等金属汞齐中的Cu，还是按上一次相同的比例(数)与汞重新结合，生成Cu汞齐，剩余部分的Cu继续与除了汞以外的金属结合，生成了与Cu有关的金属间化合物，这将导致残存在液态汞中与Cu有关的金属间化合物的浓度持续增加。在进行溶出反应时，由于富集到液态汞中的Cu等金属汞齐中的Cu，还是按上一次相同的比例(数)与汞重新结合，生成Cu汞齐，就会发生能测量出偏低的稳定重复的Cu溶出峰的现象。
当采用本发明的分析条件，在被测的样品中加入浓度是2mg/l的Cd标准溶液30μL时，在进行富集反应后，由于测量的洁净淡水样品中的Zn、Cd和Pb离子总的浓度发生了变化，导致液态汞中Zn、Cd和Pb汞齐总的浓度明显提高，与液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度仅略微提高，富集到液态汞中生成Cu等金属汞齐和干扰汞齐，还有残存在液态汞中与Cu有关的金属间化合物和与干扰金属有关的金属间化合物，还会在液态汞中重新结合反应，富集到液态汞中的Cu等金属汞齐中的Cu，与汞重新结合的比例(数)提高，就会生成更多的Cu汞齐，同时残存在液态汞中与Cu有关的金属间化合物中的Cu，也将部分或全部重新与汞结合，生成Cu汞齐。在进行溶出反应时，由富集到液态汞中的Cu汞齐中的Cu，生成的Cu汞齐，还有残存在液态汞中与Cu有关的金属间化合物中的Cu转化生成的Cu汞齐，就会导致测量的Cu溶出峰明显增高的现象发生。以上实验，不仅Pb和Cd有可能会以与Pb或Cd有关的金属间化合物的形式残存在液态汞中，Cu也会以与Cu有关的金属间化合物的形式也残存在液态 汞中，理论上讲只要生成与Cd、Pb和Cu有关的金属间化合物，就会对测量的Cd、Pb和Cu结果造成影响，因此虽然本发明的分析方法的分析条件，能测量出Cu溶出峰，但如果部分的Cu转化为与Cu有关的金属间化合物，理论上会对测量Cu的准确性造成影响，合理的解释参见实验7—阳极溶出伏安法采用现有的分析条件，测量1μg/L Pb的μg/L级海水样品的回收率实验，和实验10--阳极溶出伏安法采用本发明的分析条件测量1μg/L海水样品中的Pb实验。需要说明的是，在实验7和实验10是对Pb的讨论和解释，但是对Pb的讨论和解释，同样适用于Cu。
实验6
电解池的洗涤方法、样品取液量、仪器参数设置均与实验2相同，富集360s，得到溶出谱图6-1，延长富集时间到999s，得到溶出谱图6-2，可以看出反复多次富集与溶出，不能测量出洁净的海水样品中的Cd、Zn和Pb溶出峰，能测量出Cu溶出峰的现象与实验4的现象相同，详细的解释见实验4。
采用本发明的分析方法的分析条件，在被测样品中加入浓度是10mg/l的Pb标准溶液30μL(这里选择了用Pb标准溶液代替含有Pb离子的试剂)，提高测量样品中Zn、Cd和Pb离子总的浓度，不改变任何参数，继续测量，扫描溶出，溶出谱图见图6-3，可以测量出满刻度的Pb溶出峰，和较高Cd、Zn溶出峰，Cu溶出峰明显的增高。用本发明的阳极溶出伏安法富集反应与溶出反应测量原理可以给出合理的解释，同实验4。Cu溶出峰明显的增高的现象与实验5中的Cu完全相同，详细的解释见实验5。
实验7
阳极溶出伏安法采用现有的分析条件，具备测量1μg/L Pb的μg/L级海水样品的能力，问题是阳极溶出伏安法采用现有的分析条件，是否具备(较为准确)测量1μg/L Pb的μg/L级海水样品的能力？
由于目前我国没有浓度为1μg/L的海水介质的Pb标准样品，本实验中是在洁净的海水样品中的Pb忽略不计的前提下，采用以下的方法配制1μg/L的海水样品：电解池采用现有洗涤方法洗涤，洗涤干净后，用移液器取洁净的酸性(pH＝4-5)的海水20.0ml，加浓度是1mg/L的Pb标准溶液20μL，标准溶液稀释1000倍，配制出1μg/L的海水样品。以下我们将含有1μg/L Pb的海水或淡水样品，称为较为洁净的海水或淡水样品。假如测量结果是1μg/L，可以推断回收率是100％。
仪器参数按照仪器默认的仪器参数设置，富集时间为60秒，开始测量，扫描溶出，见溶出谱图7-1，能测量出Pb溶出峰，连续测量2次Pb溶出峰，峰高分别为1.17和1.29， 连续测量的两次峰高稳定重复。在被测样品中继续加入浓度为1mg/L的Pb标准溶液40μL，继续测量，扫描溶出，见溶出谱图7-2，Pb溶出峰明显的增高，连续测量的两次Pb溶出峰峰高分别为47.94和47.30，也稳定重复，按照阳极溶出伏安法计算浓度的公式计算，浓度为0.05μg/L。回收率仅为5％，测量1μg/L海水样品中的Pb，测量的结果严重偏低，回收率同样严重偏低。
以上，虽然阳极溶出伏安法采用现有分析方法的分析条件能测量海水样品中1μg/L Pb，在能测量出稳定重复的加标前Pb溶出峰与稳定重复的加标后Pb溶出峰的前提下，但测量的结果却严重偏低，回收率仅为5％。为什么阳极溶出伏安法采用现有分析方法的分析条件测量较为洁净的海水样品中1μg/L Pb，在能测量出稳定重复的加标前与加标后的Pb溶出峰的前提下，测量的结果却严重偏低？由于富集到液态汞中的干扰汞齐，还有残存在液态汞中的与干扰金属有关的金属间化合物会在液态汞当中发生重新结合反应，残存在液态汞中的与干扰金属有关的金属间化合物中的干扰金属，与除了汞以外的金属结合，继续生成与干扰金属有关的金属间化合物，富集到液态汞中的干扰汞齐中的干扰金属，也与除了汞以外的金属结合，生成与干扰金属有关的金属间化合物，这导致液态汞中的与干扰金属有关的金属间化合物的浓度只能增加，不能减少的现象发生，这样如果银基汞膜工作电极测量样品的数量越多，液态汞中残存与干扰金属有关的金属间化合物的浓度将越高，如果液态汞中残存与干扰金属有关的金属间化合物的浓度越高，将导致液态汞中残存的与Pb等金属有关的金属间化合物的浓度也将越高。当测量1μg/L的海水中的Pb，采用的银基汞膜工作电极已经测量过大量的样品，液态汞中就会残存较高浓度的与Pb等金属有关的金属间化合物和较高浓度的与干扰金属有关的金属间化合物，在进行富集反应后，由于较为洁净的海水样品中的Zn、Cd和Pb离子总的浓度比较低的原因，导致液态汞中Zn、Cd和Pb汞齐总的浓度略小于或接近干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度，富集到液态汞中Pb等金属汞齐和干扰汞齐，会与液态汞中会残存较高浓度的与Pb等金属有关的金属间化合物和较高浓度的与干扰金属有关的金属间化合物，在液态汞中会重新结合反应，残存在液态汞中较高浓度与Pb等金属有关的金属间化合物中的Pb，还是与除了汞以外的金属结合，继续生成与Pb有关的金属间化合物；由于液态汞中残存了较高浓度的与干扰金属有关的金属间化合物的原因，导致富集到液态汞中的Pb等金属汞齐中的Pb，
只有较小比例(数)的Pb能与重新与汞结合，生成Pb汞齐，而剩余(大)部分的Pb与除了汞以外的金属结合，生成与Pb有关的金属间化合物，这将导致液态汞中残存的 与Pb等金属有关的金属间化合物的浓度持续增加。在进行溶出反应时，由于富集到液态汞中的Pb等金属汞齐中的Pb，只有较小比例(数)的Pb能与重新与汞结合，生成Pb汞齐，就会形成严重偏低的Pb溶出峰。当再次或反复进行富集反应后，由于测量的较为洁净海水样品中的Zn、Cd和Pb离子总的浓度没有变化，导致液态汞中Zn、Cd和Pb汞齐总的浓度，与液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度没有变化，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中较高浓度的与Pb等金属有关的金属间化合物和较高浓度的与干扰金属有关的金属间化合物，还会在液态汞中重新结合反应，残存在液态汞中较高与Pb等金属有关的金属间化合物中的Pb等金属，继续与除了汞以外的金属结合，继续生成与Pb有关的金属间化合物，富集到液态汞中的Pb等金属汞齐中的Pb，还是按上一次相同的比例(数)与汞重新结合，生成Pb汞齐，剩余(大)部分的Pb继续与除了汞以外的金属结合，生成了与Pb有关的金属间化合物，这将导致残存在液态汞中与Pb有关的金属间化合物的浓度持续增加。在进行溶出反应时，
由于富集到液态汞中的Pb等金属汞齐中的Pb，还是按上一次相同的比例(数)与汞重新结合，生成Pb汞齐，就能测量出严重偏低的稳定重复的加标前Pb溶出峰。为了计算较为洁净海水样品中Pb的浓度，在被测样品中加入浓度为1mg/l的Pb标准溶液40μL时，再次进行富集反应后，由于被测样品中加入浓度为1mg/L的Pb标准溶液40μL的原因，导致液态汞中Zn、Cd和Pb汞齐总的浓度提高明显，而液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度仅略微提高，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中较高浓度与Pb等金属有关的金属间化合物和较高浓度的与干扰金属有关的金属间化合物，还会在液态汞中重新结合反应，富集到液态汞中的Pb等金属汞齐中的Pb，与汞重新结合的比例(数)提高，就会生成更多的Pb汞齐，同时残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，也将以一定的比例(数)或全部重新与汞结合，生成Pb汞齐。在进行溶出反应时，由富集到液态汞中的Pb汞齐中的Pb，生成的Pb汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物中的Pb转化生成的Pb汞齐，就会测量出严重偏高的Pb溶出峰，当再次富集反应后，由于(上一次溶出反应)残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，是较大或大部分或全部与重新与汞结合，生成Pb汞齐，通过溶出反应进入到被测的样品中，此时被测样品中的Zn、Cd和Pb离子总的浓度略微变大，导致液态汞中Zn、Cd和Pb汞齐总的浓度，与液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓 度的比例(数)发生变化，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中较高浓度与Pb等金属有关的金属间化合物和较高浓度的与干扰金属有关的金属间化合物，在液态汞中重新结合反应，富集到液态汞中的Pb等金属汞齐中的Pb，以与上一次接近的比例(数)与汞重新结合，生成Pb汞齐，而残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，能够与汞重新结合的比例(数)大大的降低，不能再以上一次的比例(数)重新与汞结合，而是以比上一次明显低的比例(数)重新与汞结合或不再与汞重新结合，生成Pb汞齐。在进行溶出反应时，富集到液态汞中的Pb等金属汞齐中的Pb，以与上一次接近的比例(数)与汞重新结合，生成Pb汞齐，而残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，以比上一次明显低的比例(数)与重新与汞结合或不再与汞重新结合，生成Pb汞齐，测量出的Pb溶出峰，将比上一次测量出的Pb溶出峰明显的偏低(不重复)。虽然测量出的Pb溶出峰，比上一次测量出的Pb溶出峰明显的偏低，但是测量出的Pb溶出峰仍然严重的偏高。当再次反复重复富集反应后，由于被测量的较为洁净海水样品中的Zn、Cd和Pb离子总的浓度没有变化，导致液态汞中Zn、Cd和Pb汞齐总的浓度，与液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度的比例(数)没有变化，富集到液态汞中Pb等金属汞齐和干扰汞齐，会与液态汞中会残存一定浓度的与Pb等金属有关的金属间化合物和较高浓度的与干扰金属有关的金属间化合物，还会在液态汞中重新结合反应，富集到液态汞中的Pb等金属汞齐中的Pb，以上一次相同比例(数)与汞重新结合，生成Pb汞齐，而残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，也以上一次相同比例(数)与汞重新结合，生成Pb汞齐。在进行溶出反应时，富集到液态汞中的Pb等金属汞齐中的Pb，以上一次相同比例(数)与汞重新结合，生成Pb汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，也以上一次相同比例(数)与汞重新结合，也生成Pb汞齐。就会测量出严重偏高稳定重复的加标后的Pb溶出峰。综上，虽然我们能测量出稳定重复的加标前和加标后的溶出峰，但是由于测量的加标前的Pb溶出峰严重偏低，而测量的加标后的Pb溶出峰又严重的偏高，这将导致计算的结果严重的偏低，回收率也严重偏低的现象发生。需要说明的是，由于测量1μg/L的淡水样品中的Pb，实验的结果或现象与测量1μg/L的海水中Pb的结果或现象完全相同，因此本发明不再对测量1μg/L的淡水样品中的Pb进行实验验证，特此说明。
以上的实验结果表明，残存在液态汞中的与Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物会与富集到液态汞中的Pb等金属汞齐重新结合反应，从而对 测量的结果造成(严重的)影响。1)当测量洁净的海水或淡水样品中的Pb时，会发生不能测量出Pb溶出峰的现象。2)当测量较为洁净的海水或淡水样品中的Pb时会发生测量出Pb溶出峰偏低的现象。因此要想实现较为准确的测量洁净或较为洁净的海水或淡水样品中的Pb，就必除去或消除除残存在液态汞当中与Pb等金属有关的金属间化合物对测量造成的干扰，还有防止残存在液态汞中的与干扰金属有关的金属间化合物对测量造成干扰，对能否实现较为准确的测量洁净或较为洁净的海水或淡水样品中的Pb至关重要。
为了以下叙述的方便，本发明的阳极溶出伏安法或叫本发明的分析方法，其测量的原理是采用本发明的阳极溶出伏安法富集反应与溶出反应，本发明的分析条件是：1)分析样品的底液是酸性，目的是使被测样品的金属以离子的形式存在；2)被测海水样品及淡水样品中必须含有一定量的电解质，因此淡水样品中通常再加入一定量的电解质，目的是使分析样品的底液导电；以满足现有的阳极溶出伏安法富集反应与溶出反应的正常进行。3)在被测样品中加入适量高浓度的Zn或Cd或Pb离子，目的防止富集到液态汞中Pb等金属汞齐重新结合反应生成与Pb等金属有关的金属间化合物。以满足本发明的阳极溶出伏安法富集反应与溶出反应的正常进行。
实验8
阳极溶出伏安法，在被测的样品中加入适量的Zn和Cd离子，验证在洁净的海水样品中的Pb是否为ng/L级的Pb，即用于验证30多年前Tatsumoto和Patterson两位专家的预言“海水中的Pb大约是0.03ppb”的观点是否正确。
要想测量洁净的海水或淡水样品中ng/L级的Pb，第一要解决电解池的ng/L级Pb洗涤问题，第二要解决除去或消除残存在液态汞中与Pb有关的金属间化合物对测量造成干扰的难题，第三要防止富集到液态汞中Pb汞齐中的Pb，再与除了汞以外的金属结合，生成与Pb有关的金属间化合物的现象发生。至于电解池中ng/L级Pb的洗涤，由于目前国内外还没有关于ng/L级Pb洗涤的方法或洗涤技术，其难点在于采用现有的洗涤方法，采用酸性的超纯水或其它洗涤液，无法判断洗涤多少遍能保证电解池中ng/L级的Pb洗涤干净。关于残存在液态汞中与Pb等金属有关的金属间化合物除去的难题，其难点在于现有的洗涤方法理论上无法将残存在液态汞中与Pb等金属有关的金属间化合物除去或洗涤去，这个问题在国内外现有的分析方法中从没有遇到。问题是怎样才能判断残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，还有沾污在电解池中的Pb，不会对测量的ng/l级Pb造成干扰或沾污？在本实验的洗涤中，我们采用测量洗涤液Pb溶出峰的方法判断，当测量洗涤液的Pb溶出峰小于或等于或非常接近被测样品的Pb溶出峰时，可以推断液态汞或电解池中的Pb洗涤干净 或非常接近洗涤干净。需要解释的是测量洗涤液的Pb溶出峰等于或非常接近被测样品的Pb溶出峰的情况，我们可以采用被测样品作为洗涤液，而测量洗涤液的Pb溶出峰小于被测样品的Pb溶出峰的情况，理论上可以采用比被测样品中的Pb低的样品。例如采用远离岸边的海水或大洋的海水作为洗涤液，由于采集远离岸边的海水或大洋海水会受到很多因素(船)的限制，因此在本实验洗涤中，洗涤液只能选择被测样品作为洗涤液，至于淡水的洗涤，也是按照这种原理选择洗涤液。
本实验的洗涤是采用测量溶出洗涤法，是采用本发明的分析条件测量洗涤液的Pb溶出峰，更换洗涤液，再次测量Pb溶出峰，若测量的后一次的峰高比前一次的Pb溶出峰峰高明显降低，说明电解池和液态汞中存在Pb污染；这样采用本发明的分析方法的分析条件，利用洗涤液的浓度差，将残存在液态汞中的与Pb等金属有关的金属间化合物中的Pb先转化为Pb汞齐，再通过溶出的方式进入到洗涤液中，实现对残存在液态汞中的与Pb等金属有关的金属间化合物中Pb的洗涤，对电解池的洗涤，是通过测量酸性洗涤液的过程，利用洗涤液的浓度差，实现对电解池中Pb的洗涤。多次更换洗涤液并测量Pb溶出峰，直至测量的后一次的峰高与前一次的峰不再明显的降低或相等，到此所采用的洗涤液理论上只能洗涤干净到这种程度，洗涤的电解池及液态汞中的Pb是否洗涤干净？再采用相同的分析条件(仪器参数和分析条件)测量被测样品的Pb溶出峰，如果测量被测样品的Pb溶出峰峰高等于或大于或非常接近洗涤液的Pb溶出峰峰高，可以推断液态汞或电解池中的Pb洗涤干净或非常接近洗涤干净。如果测量被测样品的Pb溶出峰峰高小于洗涤液的Pb溶出峰峰高，可以推断液态汞或电解池中的Pb没有洗涤干净，这时可以采取换更干净的洗涤液的措施或用被测样品作为洗涤液，继续比较测量Pb溶出峰的峰高，直至被测样品的Pb溶出峰峰高等于或大于或非常接近洗涤液的Pb溶出峰峰高为止，这就是本发明的测量溶出洗涤法。
电解池的洗涤，采用本发明的测量溶出洗涤法，洗涤液采用了被测的样品，取pH＝3-4的洁净的海水样品20mL，加入0.1％的ZnCl溶液30μL，再加0.4mg/L的CdCl溶液30μL。将仪器参数设置与默认的参数一致，富集220s，在进行富集反应后，由于洗涤液中Zn、Cd和Pb总浓度较高，导致液态汞中Zn、Cd和Pb汞齐总的浓度远远大于液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物，在液态汞中重新结合反应，富集到液态汞中的Pb等金属汞齐中的Pb，与汞重新结合，生成Pb汞齐，残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，也与汞重新结合，生成Pb汞齐。在进行溶出反应时，测量出溶出谱图8-1中的Pb溶出峰，测 量Pb的溶出峰峰高为25.84。这个Pb溶出峰是富集到液态汞中生成的Pb汞齐，还有残存在液态汞中生成的Pb汞齐所形成的Pb溶出峰。由于残存在液态汞中也生成的Pb汞齐，也能形成Pb溶出峰，因此测量的峰高为25.84的Pb溶出峰严重偏高。
倒掉样品，重新取20ml洁净的海水样品加入到电解池中，采用相同的分析条件，在进行富集反应后，由于洗涤液中Zn、Cd和Pb总浓度较高，导致液态汞中Zn、Cd和Pb汞齐总的浓度远远大于液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物，在液态汞中重新结合反应，富集到液态汞中的Pb等金属汞齐中的Pb，与汞重新结合，生成Pb汞齐，残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，也与汞重新结合，生成Pb汞齐。在进行溶出反应时，测量出溶出谱图8-2中的Pb溶出峰，测量Pb的溶出峰峰高为15.78。由于再次测量的Pb溶出峰明显的降低，由此推断电解池和残存在液态汞中与Pb等金属有关的金属间化合物中的Pb没有洗涤干净，这个降低的Pb溶出峰，还是由富集到液态汞中生成的Pb汞齐，还有残存在液态汞中生成的Pb汞齐所形成的Pb溶出峰。虽然残存在液态汞中生成的Pb汞齐，还能形成Pb溶出峰，但是实验的结果表明，残存在液态汞中与Pb有关的金属间化合物的浓度在降低，对残存在液态汞中与Pb等金属有关的金属间化合物中Pb的洗涤，是利用洗涤液的浓度差，在本发明的分析条件下，将残存在液态汞中与Pb等金属有关的金属间化合物中的Pb先转化生成的Pb汞齐，再通过溶出的方式进入到洗涤液中，实现了对残存在液态汞中的与Pb等金属有关的金属间化合物中Pb的洗涤，对电解池的洗涤，是通过测量酸性的洗涤液过程，利用洗涤液的浓度差，实现对电解池中的Pb的洗涤。倒掉样品，重新取20ml洁净的海水样品，采用相同的分析条件，在进行富集反应后，由于洗涤液中Zn、Cd和Pb总浓度较高，导致液态汞中Zn、Cd和Pb汞齐总的浓度远远大于液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物，在液态汞中重新结合反应，富集到液态汞中的Pb等金属汞齐中的Pb，与汞重新结合，生成Pb汞齐，残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，也与汞重新结合，生成Pb汞齐。在进行溶出反应时，测量出溶出谱图8-3中的Pb溶出峰，测量Pb的溶出峰峰高为5.03。由于再次测量的Pb溶出峰明显的降低，由此推断电解池和残存在液态汞中与Pb等金属有关的金属间化合物中的Pb没有洗涤干净，这个降低的Pb溶出峰，还是由富集到液态汞中生成的Pb汞齐，还有残存在液态汞中生成的Pb汞齐所形成的Pb溶出峰。倒掉样品，重新取20ml 洁净的海水样品，采用相同的分析条件，在进行富集反应后，由于被测样品中Zn、Cd和Pb总浓度还是较高，导致液态汞中Zn、Cd和Pb汞齐总的浓度远远大于液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物，在液态汞中重新结合反应，富集到液态汞中的Pb等金属汞齐中的Pb，与汞重新结合，生成Pb汞齐，残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，也与汞重新结合，生成Pb汞齐。在进行溶出反应时，测量出溶出谱图8-4中的Pb溶出峰，测量Pb的溶出峰峰高为4.91。由于再次测量的Pb溶出峰不再明显的降低，根据测量溶出洗涤法洗涤原理推断，电解池和残存在液态汞中与Pb等金属有关的金属间化合物中的Pb接近洗涤干净，这样对电解池和残存在液态汞中与Pb等金属有关的金属间化合物中的Pb的洗涤难题解决，由于本实验洗涤液是被测样品，此时测量的Pb溶出峰，是被测样品中的Pb离子，富集到液态汞中生成的Pb汞齐所形成的Pb溶出峰，也是最接近真值的Pb溶出峰(含试剂空白)，因此不要倒掉样品，继续测量被测样品的Pb溶出峰，当再次反复富集反应后，由于被测量的洁净海水样品中的Zn、Cd和Pb离子总的浓度没有变化，导致液态汞中Zn、Cd和Pb汞齐总的浓度，与液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度没有变化，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物，在液态汞中重新结合反应，富集到液态汞中的Pb等金属汞齐中的Pb，与汞重新结合，生成Pb汞齐，残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，将不再与汞重新结合，不再生成Pb汞齐对测量造成干扰。在进行溶出反应时，由于还是只有富集到液态汞中生成的Pb汞齐，能形成Pb溶出峰，因此理论上能测量出稳定重复的Pb溶出峰，测量出溶出谱图8-5中的Pb溶出峰，测量Pb的溶出峰峰高为4.59。连续测量的两次加标前的Pb溶出峰稳定重复(4.91和4.59)。为了计算洁净海水样品中Pb的浓度和回收率，测量回收率，加标的量控制在被测样品浓度的3倍以内，因此在电解池中加浓度为0.025mg/L的Pb标准溶液30μL(简称为加标)，换算为Pb的浓度37.5ng/L，继续进行富集反应后，虽然在被测的样品中加入了浓度为0.025mg/L的Pb标准溶液30μL，
由于被测样品中Zn、Cd和Pb总浓度还是较高，导致液态汞中Zn、Cd和Pb汞齐总的浓度还是远远大于液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物，在液态汞中重新结合 反应，富集到液态汞中的Pb等金属汞齐中的Pb，与汞重新结合，生成Pb汞齐，残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，不再与汞重新结合，不再生成Pb汞齐对测量造成干扰。
在进行溶出反应时，测量出溶出谱图8-6中的Pb溶出峰，测量Pb的溶出峰峰高为16.92。由于测量的Pb溶出峰，还是富集到液态汞中生成的Pb汞齐，形成的Pb溶出峰，这个Pb溶出峰同样是由被测样品中的Pb离子所形成的Pb溶出峰。当反复测量富集反应后，由于被测样品中Zn、Cd和Pb总浓度还是较高，导致液态汞中Zn、Cd和Pb汞齐总的浓度，与液态汞中干扰汞齐和与干扰金属有关的金属间化合物中有关汞齐或金属总的浓度没有变化，富集到液态汞中生成Pb等金属汞齐和干扰汞齐，还有残存在液态汞中与Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物，在液态汞中重新结合反应，富集到液态汞中的Pb等金属汞齐中的Pb，与汞重新结合，生成Pb汞齐，残存在液态汞中与Pb等金属有关的金属间化合物中的Pb，不再与汞重新结合，不再生成Pb汞齐对测量造成干扰。在进行溶出反应时，由于还是只有富集到液态汞中生成的Pb汞齐，能形成Pb溶出峰，因此理论上就能测量出稳定重复的Pb溶出峰，测量Pb的溶出峰峰高为15.21。连续测量的两次加标后的Pb溶出峰稳定重复(16.92和15.21)。由于本发明的分析条件能测量出稳定重复加标前与加标后的Pb溶出峰，并且都是由被测样品中的Pb离子按相同的比例(数)所形成的Pb溶出峰，且液态汞中与Pb等金属有关的金属间化合物，还有残存在与干扰金属有关的金属间化合物不再对测量造成干扰，测量结果的准确性就大大提高，根据阳极溶出伏安法浓度计算浓度公式计算，浓度为15.74ng/L。为了验证本发明的分析条件，测量的ng/L级Pb是否准确，测量回收率，继续在被测样品中加入0.025mg/l的Pb标准溶液50μL，扫描溶出，见溶出谱图8-7，连续测量两次Pb溶出峰分别为34.97和33.53，同样稳定重复，计算浓度为55.21ng/L，计算回收率为105.25％，良好的回收率可以推断，阳极溶出伏安法采用本发明分析方法的分析条件，测量的洁净的海水样品中的Pb是15.74ng/L的结果是准确的。这是世界上第一次在普通的实验室的环境下，采用普通的试剂(试剂没有提纯)，采用被测样品(没有采用超纯水)将电解池或残存在液态汞中μL级、ng/L级、甚至比ng/l还要低的Pb洗涤干净，验证或证明了洁净的海水样品中的Pb是ng/L级。本发明的分析方法，具有测量过程非常简单，试剂空白超低，几乎没有任何干扰，这是一种非常接近理想分析条件的分析方法，这将对我们实现更准确的测量海水或淡水样品中μL级、ng/L级、甚至比ng/L还要低的Pb具有非常重要的意义。
由于本发明的分析方法存在无法扣除试剂空白的缺陷以及本实验采用的样品处理方 法理论上会导致测量结果偏高的原因，因此本发明的分析方法测量的洁净海水中的Pb理论上只能偏高，不可能偏低。由此推断本发明测量的洁净的海水，即青岛市市南区银海大世界的岸边海水中的Pb，真实的结果(理论上)比15.74ng/L还要低。由于海水样品中重金属的分布是有一定的规律，通常是岸边的重金属含量高于近海海水高于远海海水，因此远离岸边海水中的Pb，理论上将比青岛市市南区银海大世界的岸边海水中的Pb15.74ng/L的结果还要低，因此青岛市市南区银海大世界的岸边海水中Pb 15.74ng/L的结果可以推断，30多年前Tatsumoto和Patterson两位专家的预言“海水中的Pb大约是0.03ppb”的观点是成立或正确，海水中的Pb，不是μg/L级，是ng/L级。这将对国内外分析工作者正确认识海水样品中的Pb具有非常重要的意义。这个结论可以推断，如果我们采用一种从样品的处理、洗涤、到测量是建立在μg/L级定量检出能力基础上的分析方法，去测量海水样品中ng/L级的Pb，测量的结果理论上讲不准确，就会发生再现性差的现象，因此现有的标准分析方法测量海水样品中的Pb再现性差，显然与海水样品中的Pb是ng/L级Pb有关。
由此我国还有国外过去的几十年测量的μg/L级海水原始数据是否准确值得商榷。
实验9
阳极溶出伏安法，采用本发明分析条件，在被测的样品中加入适量的Zn和Cd离子，测量洁净的淡水样品中的ng/L级的Pb，验证30多年前Patterson专家提出的“河水中的Pb大约是0.015ppb”观点是否正确。
采用本发明的测量溶出洗涤法，详细的洗涤过程同实验8。取洁净的酸性的(pH＝3-4)淡水20ml，加0.1％的ZnCl 30μL和浓度是0.4mg/l的CdCl 30μL，再加2ml洁净的海水，加海水的目的是用海水代替加电解质KCl，减少试剂空白。将仪器参数设置与默认的参数一致，富集时间为180秒，扫描溶出，溶出谱图见图9-1，连续两次测量Pb溶出峰峰高为1.78和1.76。这时在被测的样品中加浓度为0.025mg/l的Pb标准溶液30μL，换算成Pb的浓度为34.1ng/L，继续测量，扫描溶出，见溶出谱图9-2，连续两次测量Pb溶出峰增高为6.06和6.64，计算Pb的浓度为13.18ng/L。为了计算回收率，在样品中继续加入0.025mg/l的Pb标准溶液50μL，扫描溶出，见溶出谱图9-3，连续两次测量Pb溶出峰峰高为15.16和13.72稳定重复，计算浓度为44.60ng/L，回收率为92.14％，良好的回收率，可以推断测量的13.18ng/L结果是准确的，同样如果考虑到本发明的分析方法无法扣除试剂空白和本发明采用的样品处理方法理论上会导致测量结果偏高的原因，因此真实的结果(理论上)要比13.18ng/L的结果还要低，这个结果，可以证明，Patterson专家的提出的“河水中的Pb大约是0.015ppb”，的这种ng/L级的河水样品的确存在。这将对国内外分析工作者正确认识淡水样品中的Pb，同样具有非 常重要的意义。与海水中的Pb不同的是，淡水样品中的Pb，会受到很多因素的影响，没有一定的分布规律，但是洁净的淡水样品中的Pb是13.18ng/L的结果至少可以推断，淡水样品中的Pb从ng/L级到μg/L级的Pb都是有可能存在的，假如我们采用一种样品的处理和洗涤是建立在μg/L级的基础上，测量是采用一种最低检测质量浓度仅为2.5μg/L的无火焰原子吸收分光光度法的技术方案，去测量从ng/L级到μg/L级(Pb)浓度范围内的样品，
测量的结果理论上讲会存在问题，同样会发生再现性差的现象，因此现有的标准分析方法测量淡水样品中的Pb，常常发生再现性差现象，显然与淡水样品中的Pb从ng/L级到μg/L级都有可能存在有关。因此我国还有国外过去的几十年测量的μg/L级淡水原始数据是否准确同样值得商榷。
通过以上实验结果表明，阳极溶出伏安法采用本发明的分析条件，虽然富集到液态汞中的Pb等金属汞齐，还会与富集到液态汞中的干扰汞齐，还有残存在液态汞中的与Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物之间重新结合反应。由于富集到液态汞中的Pb等金属汞齐中的Pb，只能与汞重新结合，生成Pb汞齐，不会发生与除了汞以外的金属结合，生成与Pb等金属有关的金属间化合物的现象。因此只要延长富集时间，富集到液态汞中的Pb汞齐的浓度会不断的增加，这将导致本发明的阳极溶出伏安法是一种检出的溶出峰峰高与富集时间有关的电化学分析方法。
实验10
验证本发明的分析方法，是否比现有的分析条件测量1μg/L的μg/L级的Pb更准确。电解池的洗涤，理论上测量μg/L级的Pb，比测量ng/L级Pb洗涤的难度大大的降低，但是无论测量μg/L级Pb，还是测量ng/L级Pb，只要满足测量洗涤液的Pb溶出峰低于或等于被测样品中的Pb溶出峰，就能保证洗涤干净(Pb)，因此对于测量μg/L级的Pb，通常采用现有的的洗涤方法洗涤1-2次，再采用本发明的测量溶出洗涤法洗涤(1-2次)验证测量的洗涤液的Pb溶出峰，是否低于或等于被测样品中的Pb溶出峰即可。在本实验是洗涤中，洗涤液采用了洁净的海水，用移液器取pH＝3-4的酸性洁净的海水20ml，加0.1％的ZnCl 30μL。仪器参数按照仪器默认的仪器参数设置，富集时间为30秒，灵敏度为10，开始测量，扫描溶出，见溶出谱图10-1，测量Pb溶出峰峰高为2.20。倒掉洗涤液，分析条件不变，用移液器取pH＝3-4的酸性洁净的海水20.0ml，加浓度是1mg/L的Pb标准溶液20μL，前提是洁净的海水中的Pb忽略不计，配制出1μg/L的海水样品。在样品中加0.1％的ZnCl 30μL。继续测量扫描溶出，见溶出谱图10-2，连续测量两次Pb溶出峰的峰高分别为8.35和7.86，被测样品的Pb溶出峰峰高(8.35和7.86)，大于洗涤液的Pb溶出峰的 峰高(2.20)，证明了电解池和液态汞中的Pb洗涤干净，继续测量，在被测样品中加1mg/L的Pb标准溶液,40μL后，扫描溶出，见溶出谱图10-3，Pb溶出峰明显的增高，连续测量两次Pb溶出峰峰高分别为23.47和23.37，计算浓度为1.06μg/L，回收率为106％，良好的回收率，可以推断测量较为洁净的海水样品中1μg/L的μg/L级的Pb是准确的，详细的解释见实验8。需要说明的是，由于测量1μg/L的淡水样品中的Pb，实验的结果或现象与测量1μg/L的海水中Pb的结果或现象完全相同，因此本发明不再对测量1μg/L的淡水样品中的Pb进行实验验证，特此说明。
实验11
阳极溶出伏安法采用本发明的分析方法测量强酸介质(pH＝1)的土壤样品中的Pb。需要解释的是现有的无火焰原子吸收分光光度法或现有的阳极溶出伏安法等分析方法是不能直接对土壤、海洋沉积物、生物体、生物组织、食品、药品等介质复杂的样品(简称为土壤等介质复杂样品)中的Pb等重金属进行直接测量，需要进行样品处理，比如国内外经常采用的微波消解法或湿法消解法，将土壤等介质复杂样品用强酸消解成溶液再进行测量。本发明的分析方法也是同样，以下以测量土壤样品为例，验证本发明的分析方法是否具备较为准确的测量土壤样品中Pb的能力。
本实验的土壤样品处理是采用国内外经常采用的硝酸-盐酸-高氯酸的湿法消解处理方法，将称量的土壤样品至于消解器皿中，再加入适量的硝酸和盐酸在电热板上加热煮沸消解(加酸消解的过程可以是一次或多次)，待消解到近干，再加入高氯酸进一步消解至近干，再加入适量的硝酸和水煮沸，将处理的土壤样品定容至10ml，沉淀1-2天再测量。需要说明的是，在以上的样品处理方法中没有刻意的将高氯酸赶尽的过程，这将使消解土壤样品的工作量大大的降低，但这将导致消解的样品中将含有很高浓度的高氯酸，并且消解低液的pH＝1酸性非常强。
采用本发明的测量溶出洗涤法洗涤电解池，洗涤的过程同实验10。电解池洗涤干净后，将湿法消解沉淀的(10ml)样品转移至电解池中，加海水定容至15mL，此时样品是强酸的介质，pH＝1，并且含有很高浓度的高氯酸。为了消除强酸介质对测量的干扰，保证测量的溶出谱图稳定重复，本发明的分析方法在被测的样品中加入了(超高浓度的)浓度为5％的ZnCl300μL。按照仪器默认的仪器参数设置，富集时间为30秒，灵敏度为6，开始测量，扫描溶出，溶出谱图见图11-1，连续测量2次Pb溶出峰的峰高分别为11.23和11.65，从测量的溶出谱图11-1中可以看出，被测样品中很高浓度的高氯酸和强酸介质(pH＝1)没有给测量结果造成干扰。继续测量，在被测样品中加4mg/L的Pb标准溶液 30μL后，扫描溶出，见溶出谱图11-2，连续测量2次Pb溶出峰峰高分别为27.96和29.40，计算浓度为5.31μg/L。为了验证测量的结果是否准确，测量回收率，在被测样品中加4mg/l的Pb标准溶液50μL后继续测量扫描溶出，见溶出谱图11-3，连续测量2次Pb溶出峰峰高分别为57.12和56.58，计算结果13.58μg/L，计算回收率为103.4％，良好的回收率，证明采用本发明的分析方法测量土壤样品中的Pb是准确的，详细的解释见实验8。
需要解释的是现有的阳极溶出伏安法采用现有的分析条件，也可以测量土壤等介质复杂样品中的Pb等重金属，但要对消解的强酸介质样品，用强碱回调pH，再用弱碱氨水回调至pH＝4-5再测量，这导致工作量加大，试剂空白增加的缺陷。本发明是采用pH＝1的强酸介质下直接测量，为什么现有的阳极溶出伏安法不能在pH＝1的强酸介质下直接测量？这是因为测量强酸介质(pH＝1)的样品，被测的样品中将含有大量的H离子，在进行富集反应时，被样品中大量的H离子将被富集还原生成氢气(气泡)，附着在液态汞表面，在进行溶出反应时，这些附着在银基汞膜工作电极表面的氢气气泡非常容易破损，氢气气泡破损后，将严重干扰银基汞膜工作电极表面正常的溶出电流的扩散，导致测量的溶出谱图出现很多随机的不能重复的干扰峰，除了使测量的Pb等金属的溶出峰不能稳定重复，更严重时会将银基汞膜工作电极的汞膜破坏，从而对测量造成严重的干扰。由于Zn离子的半波电位与氢离子的半波电位非常接近，如果我们采用本发明的分析条件，在被测的样品中加入高浓度的Zn离子(5％的ZnCl300μL)，虽然测量的样品含有大量的H离子(pH＝1)，由于样品中Zn离子的浓度很高，在进行富集反应时，被测样品中的Zn离子将首先富集到液态汞中还原生成大量的Zn汞齐，由于液态汞中含有高浓度的Zn汞齐，就可以防止被测样品中高浓度H离子被富集到液态汞中还原生成氢气，由于银基汞膜工作电极表面没有大量的氢气气泡生成，在进行溶出反应时，高浓度的H离子就不会对测量造成干扰，就能测量出稳定重复的溶出谱图。因此在被测样品中加入较高或高浓度或超过浓度的Zn离子，可以防止被测样品中较高或高浓度H离子被富集到液态汞中还原生成氢气造成干扰，这对能测量出洁净的海水或较为洁净的海水、淡水、土壤等等样品稳定重复的Pb等金属溶出峰具有非常重要的意义，这也是为什么阳极溶出伏安法采用现有的分析条件，分析的低液pH通常在4-5最佳，而本发明的分析条件，分析低液可以选择pH1-5的主要的原因。
需要说明的是，实验11是建立在阳极溶出伏安法采用现有的分析条件也能测量土壤等介质复杂样品中的Pb等金属的基础上进行的，虽然阳极溶出伏安法采用现有的分析条件也能测量土壤等介质复杂样品中的Pb等金属，但必须回调分析低液的pH至弱酸性，但是阳极溶出伏安法采用本发明的分析条件，在被测的样品中加入了高浓度的Zn离子，可以实 现强酸介质(pH＝1)下的直接测量，这使得测量的过程更简单，测量的结果更准确，这将对测量土壤等介质复杂的样品中更低浓度的Pb具有非常重要的意义。
实验12
实验的目的；理论上阳极溶出伏安法不仅可以测量Zn、Cd、Pb和Cu，还可以测量除了Zn、Cd、Pb和Cu以外的金属，例如本实验测量μg/L级的In。本实验中采用以下的方法配制1μg/L的In海水样品：前提是海水中的In忽略不计，电解池采用测量溶出洗涤法，电解池洗涤干净后，用移液器取pH＝3-4的酸性的洁净海水15.0ml，加浓度是0.5mg/L的In标准溶液30μL，标准溶液稀释500倍，配制出1μg/L的In海水样品。采用本发明的分析条件，
在被测的样品中加入浓度为0.1％的ZnCl 30μL，按照仪器默认的仪器参数设置，富集时间为30秒，开始测量，扫描溶出，见溶出谱图12-1，连续测量2次In溶出峰的峰高分别为7.62和7.72，稳定重复。在被测样品中加0.5mg/L的In标准溶液50μL后，继续测量扫描溶出，见溶出谱图12-2，连续测量2次In溶出峰峰高分别为20.29和20.02，计算浓度为1.02μg/L，回收率为102％。良好的回收率，说明采用本发明的分析条件，在被测的样品中加入适量的Zn离子，可以准确的测量出1μg/L浓度的In。本实验，是建立在阳极溶出伏安法采用现有的分析条件，也能测量In的基础上进行的，至于为什么能测量In，是因为液态汞中的确存在In汞齐，但是采用本发明的分析条件，可以防止富集到液态汞中的In汞齐与除了汞以外的金属结合，生成与In有关的金属间化合物，因此本发明的分析条件测量In的浓度更低，测量的结果也更准确。详细的解释参见实验8。需要说明的是实验8是测量Pb，但对Pb的解释同样适用In，因此本发明不再对In的测量进行详细的解释。
综合以上；
1、关于本发明分析条件的问题，由于本发明问题的引出是对现有的分析方法唯独测量洁净的海水或淡水中的Pb存在问题，本发明测量的重点也是Pb，因此在实际的测量中，在被测样品中加入适量的Pb离子的分析条件，很少采用或根本不被采用，这里实验的目的，仅仅是为了证明在被测样品中加入适当浓度的Pb离子溶液，能控制发生在液态汞中的重新结合反应向左进行，能测量出Cd溶出峰，Cu溶出峰明显的增高而已。在实际的测量中，测量比μg/L更低浓度的Pb最佳的分析条件，是在被测样品中加入适量的Zn离子及再加入适量的Cd离子，这有益于测量的比μg/L更低浓度的ng/L级Pb溶出峰更稳定重复。最常用的分析，是在被测样品中加入适量的Zn离子，这种分析条件有利于Cd、Pb和Cu的同时测量。
2、关于分析低液的酸度问题，阳极溶出伏安法采用现有的分析，分析样品的底液是pH＝3-5的酸性，优选为pH＝4-5，目的除了使被测样品的金属以离子的形式存在，以保证阳极溶出伏安法的富集反应和溶出反应的顺利进行，还有分析低液采用弱酸性介质，可以防止被测样品中的H离子，富集到液态汞中还原生成氢气，对测量溶出谱图造成干扰，有利于测量出更为稳定重复的溶出谱图。当采用本发明的分析条件，分析样品的底液是pH＝1-5的酸性，优选为pH＝3-4，目的同样是除了使被测样品的金属以离子的形式存在，以保证阳极溶出伏安法的富集反应和溶出反应的顺利进行，还有在被测的样品中加入较低浓度或较高浓度或超高浓度Zn离子，是为了分析低液可以采用酸性更强的介质，比如实验11中pH＝1也能直接测量，这将对对减少试剂空白，还有测量的过程更为简单，工作量的降低非常有益。至于为什么本发明的分析条件在pH＝1的强酸介质也能测量，详细的解释见实验11。因此本发明分析条件的分析低液pH＝1-5的范围，优于现有的分析条件的分析低液pH＝3-5的范围。
3、关于加入适量的Zn和/或Cd离子的量问题，在样品中加入(较低浓度或较高浓度或超高浓度)Zn离子的目的或作用，1、防止被测样品中较高或高浓度的H离子，富集到液态汞中还原生成氢气，对测量溶出谱图造成干扰，有利于测量出更为稳定重复的溶出谱图；2、防止富集到液态汞中的Pb等金属汞齐，与富集到液态汞中干扰汞齐，还有残存在液态汞中与干扰金属有关的金属间化合物重新结合反应，生成与Pb等金属有关的金属间化合物。在样品中加入(较低浓度或较高浓度)Cd离子的目的或作用，主要是为了测量ng/L级Pb溶出峰更稳定重复。因此本发明的分析条件在被测样品中加入Zn和/或Cd离子，不仅仅是考虑到富集到液态汞中的Pb等金属汞齐和干扰汞齐，还有残存在液态汞中Pb等金属有关的金属间化合物和与干扰金属有关的金属间化合物，在液态汞中重新结合反应，生成与Pb等金属有关的金属间化合物的问题，还要考虑被测样品中较高或高浓度的H离子，能否对测量溶出谱图造成干扰，能否测量出稳定重复的溶出峰的问题。由于发生在液态汞中的重新结合反应，是各金属汞齐以及各金属间化合物中的金属与金属之间的反应，反应的机理非常复杂，至于什么金属什么浓度能够与Pb等金属汞齐进行重新结合反应，不详，由于现有的理论无法对重新结合反应反应的机理给出详细的合理的解释的原因，因此我们无法准确计算出加入多大浓度的Zn和/或Cd和/或Pb离子能够控制液态汞中发生的重新结合反应向左进行。综合以上，本发明在被测样品中加入Zn和/或Cd离子的量，通常选择加入过量的Zn和/或Cd离子，如何控制过量或合适的量？是以能测量出较大或满刻度的Zn溶出峰为合适的量，如果测量的Zn溶出峰较小，需要再加入Zn 离子试剂，直至能测量出较大或满刻度的Zn溶出峰为止。在被测样品中加入Cd离子的量，通常以能测量出较大(也可满刻度或明显)的Cd溶出峰为合适量。因此得出Zn和Cd的最大量上限分别为2％和0.2％。本发明加入Zn和/或Cd离子最小的量，还是由于发生在液态汞中的重新结合反应，是各金属汞齐以及各金属间化合物中的金属与金属之间的反应，反应的机理非常复杂，同样由于现有的理论无法对重新结合反应反应的机理给出详细的合理的解释的原因，我们同样无法准确计算出加入多少的Zn和/或Cd离子的量，能够控制液态汞中发生的重新结合反应向左进行。因此本发明加入Zn和/或Cd和/或Pb离子最小的量，只要目的是根据本发明阳极溶出伏安法富集反应与溶出反应测量的原理测量，在被测样品中加入哪怕很少的量，例如Zn离子溶液的质量浓度为1×10-15％；Cd离子溶液的浓度是1×10-15％，也对本发明造成侵权。需要解释的是，在本发明的实验中，Zn离子试剂是采用了ZnCl试剂，但ZnNO3、Zn2SO4等含Zn离子的试剂同样可以采用。Cd离子的试剂是采用了Cd标准溶液代替，但CdCl2、CdSO4等含Cd离子的试剂同样可以采用。
4、关于本发明分析条件的问题，本发明的分析条件是在被测样品中加入Zn和/或Cd和/或Pb离子的试剂，由于发生在液态汞中的重新结合反应，是各金属汞齐以及各金属间化合物中的金属与金属之间的反应，反应的机理非常复杂，现有的理论无法对重新结合反应机理给出详细的合理的解释的原因，因此我们无法推断是否还有其它的金属离子，也能控制液态汞中的重新结合反应向左进行，但是只要能控制液态汞中的重新结合反应向左进行的其它金属离子，也属于本发明的分析条件要保护的范围，因此本发明的分析条件是，包括但不限于Zn和/或Cd和/或Pb离子的试剂。
5、关于洗涤问题，由于本发明问题的引出是现有的分析方法唯独测量洁净的海水或淡水中的Pb存在问题，重点是测量Pb，因此本发明洗涤是以Pb为参照，实现对电解池及液态汞中的Pb洗涤，由于本发明的测量溶出洗涤法不仅可以以Pb为参照，实现对电解池及液态汞中的Pb洗涤，还有可以以Cd、Cu、In等金属为参照，实现对电解池及液态汞中的Cd、Cu、In等金属的洗涤，但采用本发明的测量溶出洗涤法，实现对电解池及液态汞中的Cd、Cu、In等金属的洗涤均在本发明的保护范围内。
6、关于保护(金属)的范围问题，以上本发明的分析条件能够测量的金属是Cd、Pb、Cu和In。由于发生在液态汞中的重新结合反应，是各金属汞齐以及各金属间化合物中的金属与金属之间的反应，反应的机理非常复杂，现有的理论无法对重新结合反应机理给出详细的合理的解释的原因，我们无法推断是否还有其它的金属离子，采用本发明的分析条件也能测量，如果有其它的金属离子，也能根据本发明阳极溶出伏安法富集反应与溶 出反应测量的原理测量，也在本发明的保护范围。因此本发明保护(金属)的范围是，包括但不限于Cd、Pb、Cu和In。
7、关于对Cd和Cu的讨论或实验问题，由于本发明问题的引出是Pb，且现有的分析方法唯独测量Pb存在很多的问题，因此本发明仅以测量Pb为例进行了详细的实验和讨论，但本发明中对Pb的解释，同样适用于对Cd、Cu和In存在的问题或现象的解释，因此本发明中不再对Cd和Cu进行实验验证或详细解释，特此说明。
8、以上的实验结果表明，本发明的分析方法，不仅具备准确测量μg/l级Pb的定量检出能力，还具备较为准确测量ng/L级Pb的能力，因此本发明的分析方法不仅可以作为测量海水或淡水样品中的μg/L级的Pb的分析方法，还可以作为ng/L级Pb的分析方法，还可以作为测量土壤、沉积物、食品等介质复杂的样品中Pb的分析方法，还可以作为测量上述样品中Cd、Cu和In的分析方法，因此以上方法的测量均属于本发明的保护范围之内。
9、以上的实验结果表明，本发明的分析方法，不仅具备准确测量μg/l级Pb的定量检出能力，还具备较为准确测量ng/L级Pb的能力，还具备良好的回收率，良好的回收率证明了本发明的分析方法具备较为准确测量海水、淡水、土壤、沉积物、食品等介质复杂的样品中Pb的能力，从分析技术的角度来讲，理论上具备一种作为研制海水、淡水、土壤、沉积物、食品等复杂介质(Pb)标准物质或标准样品的能力的分析方法，即定值海水、淡水、土壤、沉积物、食品等复杂介质(Pb)标准物质或标准样品的能力的分析方法，因此如果采用本发明的分析方法，作为定值海水、淡水、土壤、沉积物、食品等复杂介质中的Pb、Cd、Cu和In标准物质或标准样品的分析方法，也属本发明的侵权范围。

Claims (10)

  1. 一种改进的电化学分析方法，其特征在于，采用阳极溶出伏安分析方法，是依据如下反应式实现的：
    富集反应：
    Figure PCTCN2017070944-appb-100001
    溶出反应：Rn++ne(+Hg)←R(Hg)
    其中；
    Rn+-表示能够形成溶出峰的金属离子，包括但不限于Zn、Cd、Pb和Cu离子；
    Nn+-表示不能形成溶出峰的金属离子；
    R(Hg)–表示能够形成溶出峰的金属汞齐，包括但不限于Zn、Cd、Pb和Cu汞齐；
    N(Hg)–表示不能形成溶出峰的金属汞齐；
    RN-表示金属间化合物。
  2. 一种改进的电化学分析方法，其特征在于，采用电位溶出法分析方法，是依据如下反应式实现的：
    富集反应：
    Figure PCTCN2017070944-appb-100002
    溶出反应：R(Hg)+1/2O2+2H+→Rn++Hg+H2O
    其中；
    Rn+-表示能够形成溶出峰的金属离子，包括但不限于Zn、Cd、Pb和Cu离子；
    Nn+-表示不能形成溶出峰的金属离子；
    R(Hg)–表示能够形成溶出峰的金属汞齐，包括但不限于Zn、Cd、Pb和Cu汞齐；
    N(Hg)–表示不能形成溶出峰的金属汞齐；
    RN-表示金属间化合物。
  3. 根据权利要求1或2所述的一种改进的电化学分析方法，其特征在于，步骤如下：
    1)采集样品，进行样品处理，得到酸性的、含有电解质的待测样品，使得被测样品中的金属以离子的形式存在并且能够导电；2)洗涤电解池及液态汞；3)向待测样品中加入Zn和/或Cd离子溶液，然后采用极谱仪进行测量。
  4. 根据权利要求3所述的一种改进的电化学分析方法，其特征在于，所述步骤2)洗涤电解池及液态汞采用测量溶出洗涤法的操作方法为：在极谱仪的电解池中加入洗涤液与Zn和/或Cd溶液的混合液，测量混合液的待测金属溶出峰；然后更换电解池中的混合液，再次测量同一待测金属溶出峰，若后一次的待测金属溶出峰峰高比前一次的峰高明显降低，说明电解池和液态汞中存在该待测金属污染；多次更换混合液并测量同一待测金属溶出峰，直至后一次 的峰高与前一次的峰高接近或相等，则说明电解池及液态汞洗涤干净；所述洗涤液中待测金属浓度低于或等于待测溶液中相应金属的浓度。
  5. 根据权利要求3或4所述的一种改进的电化学分析方法，其特征在于，所述步骤2)或3)中向待测样品中加入Zn离子溶液后，待测样品的质量浓度为1×10-15％-2％；加入Cd离子溶液后，待测样品的的浓度是1×10-15％-0.2％。
  6. 根据权利要求4所述的一种改进的电化学分析方法，其特征在于，所述待测金属为Pb、Cd、In和Cu。
  7. 根据权利要求3所述的一种改进的电化学分析方法，其特征在于，所述待测样品的pH≤5。
  8. 根据权利要求3所述的一种改进的电化学分析方法，其特征在于，所述采集样品，采集海水样品的天气，选择风力小，海水透明度高的天气；采集海水样品的时间，选择海水低潮后一小时后采集；采集样品的地点，采集远离岸边残存在较大礁石上的海水水体；采集的淡水样品，选择风力小的天气，选择上游的河水。
  9. 根据权利要求3所述的一种改进的电化学分析方法，其特征在于，所述样品处理的方法有多种：1)对样品不过滤不加酸，静置于样品瓶中，测量时取上清液；2)对样品不过滤不加酸，静置6-36h后将上清液导入另一个样品瓶中，再加酸保存，适合于清澈的样品处理；3)对样品离心处理，取上清液，再加酸酸化样品，适用于当天采集的浑浊的样品；4)吸附样品处理法，方法是采用两个或多个容器采集样品，静置至少12h，每个容器都会发生吸附现象，样品中的悬浮颗粒自然沉降，扰动其中一个容器A并倒掉样品，目的将沉淀于容器底部的悬浮颗粒随样品一起倒出，得到一个已经发生吸附现象的空容器，将其它容器中同样已经发生吸附现象的样品的上清液B转移到容器A中，再加酸酸化样品，吸附到容器A内壁的离子重新溶于上清液B中；5)对样品用滤膜过滤后加酸酸化。
  10. 根据权利要求1所述的一种改进的电化学分析方法应用于测量经过酸消解处理的土壤、食品、生物材料样品中的金属离子浓度；或作为定值海水、淡水、土壤、生物体、食品样品中标准物质或标准样品的分析方法的应用。
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