CN101957336A - Method for improving detection accuracy of electrochemical active metal ions - Google Patents
Method for improving detection accuracy of electrochemical active metal ions Download PDFInfo
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- CN101957336A CN101957336A CN2009101581699A CN200910158169A CN101957336A CN 101957336 A CN101957336 A CN 101957336A CN 2009101581699 A CN2009101581699 A CN 2009101581699A CN 200910158169 A CN200910158169 A CN 200910158169A CN 101957336 A CN101957336 A CN 101957336A
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Abstract
The invention relates to the improvement of a cathodic stripping voltammetric method, in particular to a method for normatively adding another kind of internal standard metal ions with electrical activity into a reaction system to eliminate the influence on a detection result due to factors such as the non-uniformity of charges on the surface of a screen electrode, and the like and correct data obtained for detecting the concentration of metal ions by a voltammetric detection method so as to improve the accuracy of a detection result of an anodic stripping voltammetric method.
Description
Invention field
The present invention relates to the improvement of electrochemical analysis method, particularly relate in reaction system, the standard adding has electroactive another kind of interior standard gold and belongs to ion, presses the resulting data of voltammetry detection concentration of metal ions to proofread and correct, thus the accuracy that improves the anodic stripping voltammetry testing result.
Background of invention
In electrochemical analysis work, experimental result usually is subjected to the interference of multiple factor easily, and these influence factors comprise whether the clean-up performance of electrode surface, detection sample are subjected to contaminating impurity.The particularly surface flatness of working electrode, surface area and surface charging state tend to make a big impact to electrochemical analysis result's accuracy and reappearance.Therefore, need do pre-service strictly, with accuracy and the reliability of guaranteeing experimental result to used electrode.For addressing this problem, the method that often adopts is that working electrode surface is carried out physics or chemical polishing processing at present, perhaps uses disposable electrode.
Though these classic methods can guarantee electrochemical analysis result's reliability to a certain extent, still exist many drawbacks.For example, the method for physics or chemical polishing operation more complicated is high to experimenter's operating experience requirement.In addition, chemical polishing is also very high to the purity requirement of polishing reagent.Simultaneously, all there is the long problem of required-time of handling in these two kinds of classic methods.
Though use the disposable electrode can the handled easily personnel, the influence that its repeatability is subjected to technology for preparing electrode be bigger.The instability of technology for preparing electrode must make the disposable electrode surface be difficult to reach highly consistent, finally has influence on the repeatability of electrochemical analysis.In this case, the concentration of material to be checked just is difficult to accurately be determined in the sample, and is particularly particularly outstanding when substrate concentration to be checked is very low, has a strong impact on the detection accuracy.
Summary of the invention
An object of the present invention is to provide a kind of method that electrochemical process detects the detection degree of accuracy of trace metal ion concentration in the sample of improving, it is characterized in that using screen printing electrode or other electrodes, in reaction system standard add specific concentrations another kind of metallic ion and with sample synchronous detection to be checked, after detection is finished, according to formula T=A * C/B (mol/L), testing result is proofreaied and correct, to improve the accuracy of testing result, wherein A is the concentration known of interior mark ion of add, B is the interior mark ion concentration (mol/L) that records, and C is the concentration of the sample metallic ion that records.
According to method of the present invention, the detected signal magnitude of 1 wherein employed adding " interior mark ion " becomes positive correlation with object ion detected signal value to be measured size, so can testing result be proofreaied and correct according to formula T=A * C/B mol/L, to improve the accuracy of testing result.Among the present invention, the purpose of mark ion is in adding in the reaction system, eliminates the factors such as inhomogeneity owing to employed screen printing electrode surface charge, to interference and the influence that testing result caused.
According to method of the present invention, said electrochemical detection method is a voltammetry.
The method according to this invention, said metallic ion is meant the metallic ion with electrochemical activity, for example indium, lead, copper, bismuth, cadmium, mercury, gold, silver, platinum etc.
Employed detecting electrode screen printing electrode preferably among the present invention, but also can use metal film electrode, glass carbon normal electrode, goldstandard electrode, platinum normal electrode, and other any type of modified electrodes.
In the instructions of the present invention, employed term " standard adding " is meant in the reaction system of analyzing samples metal concentration, adds the standard substance of known quantity.Among the present invention, employed standard substance is the metallic ion that mercury, bismuth etc. have electrochemical activity.
The inventive method is in the electrochemical reaction system, and the standard adding has electroactive material as internal standard compound.When finishing standard detection, obtain after the experimental data, utilize above-mentioned formula that the gained data are carried out mathematics manipulation (correction) to the greatest extent, thereby guarantee the accuracy and the reliability of voltammetry testing result.
In the instructions of the present invention, employed term " mathematics correction ", be meant in the reaction system, the standard substance (standard adding) that adds concentration known (A mol/L), if if its concentration detects is B mol/L, and the concentration testing result of test substance is C mol/L, then can utilize following formula to calculate the actual concentration T of test substance, promptly
The actual concentration T=A of test substance * C/B (mol/L)
According to the present invention, wherein said screen printing electrode comprises three carbon electrodes (for example graphite working electrode), graphite to electrode and graphite reference electrode.Comprise that perhaps graphite working electrode, silver-colored silver chloride contrast electrode and graphite are to electrode.
Can select suitable electrode material according to the character of solution to be measured.In an embodiment of the present invention, detecting the electrode that copper concentration adopted is that graphite working electrode, silver-colored silver chloride contrast electrode and graphite are to electrode.
According to the present invention, said internal standard compound matter can be meant any metallic ion of electrochemical activity, also can be other organic or inorganic molecules that electrochemical activity is arranged.
The term that uses in the instructions " interior mark ion ", being meant is not influencing under the situation that ion to be checked (for example copper ion) detects, the concentration known that in reaction system, adds, as interior target metallic ion.For example, in the embodiment of this instructions, use 0.1mol/L hydrochloric acid, and working concentration is the mercuric nitrate conduct " interior mark ion " of 10 μ g/L as medium (dissociation solution).
According to the present invention, wherein said mathematical relation is meant that under the certain situation of copper and mercury concentration the ratio of the stripping signal of copper and the stripping signal of mercury is a value (both have positive correlation) of determining.Therefore can proofread and correct the stripping signal of copper according to the variation of mercury signal.
According to a preferred embodiment of the invention, wherein employed detection method is the square wave stripping voltammetry.In an embodiment of the present invention, preferred detected parameters is scanning potential region-1V～0.1V; Square wave gain 50mV; Stepping current potential 0.04V.
From the result shown in the embodiment of the invention as can be seen, through the correction of interior mark ion, can simply the deviate that detects be controlled at below 5%.Therefore, in the process that unknown sample is detected, can significantly reduce analysis times.Even after once measuring, can provide the accurate result that conforms to actual value.Thereby, accelerated the analysis speed of sample greatly, significantly reduced the loss (referring to embodiment) of reagent simultaneously.
Method of the present invention is particularly suitable for detecting the sample extremely low with the analytic sample amount.Prescribe a time limit when sample size extremely has, of the present invention improving one's methods can obtain testing result the most accurately with minimum analysis times..
Use of the present invention improving one's methods, make simple screen printing carbon electrode, promptly can be used for the metallic ion electro-deposition without further processing.Thereby got rid of owing to the uncertain factor in the printing process, the silk screen electrode surface that causes lacks the problem of homogeneity.In addition, convenience and of the present invention improving one's methods in conjunction with screen printing technique also make the metal ion sensor of mass production of cheap become possibility.
Description of drawings
Fig. 1 shows that classical anodic stripping voltammetry detects the testing result of copper ion concentration.As can be seen from the figure, at current potential be-during the 0.22V left and right sides, as seen the characteristic peak of a copper oxidation leachable is arranged.
Fig. 2 shows the testing result of using classical anodic stripping voltammetry repeated detection copper ion.As can be seen from the figure, when current potential be-during the 0.22V left and right sides, the characteristic peak repeatability of copper oxidation stripping is very poor, therefore almost can not carry out quantitative test to copper ion with voltammetry.
Fig. 3 shows that according to the method that the present invention narrated, standard adds mercury ion as the resulting anode stripping curve of interior mark in reaction system.As can be seen from the figure, be that distinctive mercury oxidation stripping peak has appearred in the 0.05V place at current potential, and be approximately at current potential-as seen the 0.22V place has the characteristic peak of copper oxidation leachable.
Anodic stripping voltammetry was repeatedly measured the testing result of copper ion concentration under the mark mercury ion existed in Fig. 4 was presented at.As can be seen from the figure, the stripping peak of the stripping peak then mercury less than normal of copper is also correspondingly less than normal.According to method of the present invention, the stripping peak number value of utilizing mercury ion is carried out mathematics to detection and is proofreaied and correct, just the actual concentration of definite copper ion that can be more accurate (referring to embodiment) the relation between the numerical value at the stripping peak of copper ion.
The mark mercury ion existed down in Fig. 5 was presented at, and repeatedly measured the testing result of low concentration copper with anodic stripping voltammetry.As can be seen from the figure, even under the situation of trace, the stripping peak of copper is less than normal, and then the stripping peak of mercury is also correspondingly less than normal.Proofread and correct through appropriate mathematical, the actual concentration of definite trace copper ion that can be more accurate, thus preferably resolve the bad problem of reappearance that runs in the trace metal ion testing process.
Fig. 6 shows that mark carries out the testing result that mathematics is proofreaied and correct in the not use.As seen experimental data that finally obtains and real data deviation very big (RSD=14.87%) can not satisfy the requirement of analyzing and testing.
Fig. 7 is presented at mercury ion and exists down, with the testing result of anodic stripping voltammetry repeated detection low concentration lead.Proofread and correct through mathematics, experimental data and the True Data deviation that finally obtains very little (RSD=2.8%) meets the analysis requirement.With compare without the testing result of interior mark quasi-molecular ions current correction, use of the present invention improving one's methods, significantly improved the accuracy of voltammetry testing result.
Embodiment
Embodiment 1: detect the lead ion in the water sample
Use above-mentioned standard addition method, preparation has determined to contain the water sample of micro-plumbi nitras (2.5 μ M) as solution to be measured.Detecting end liquor is the 0.2M acetate buffer (pH=3.4) that contains 10 μ g/L mercuric nitrates.With this water sample is detected object, and the water body of heavy-metal pollution is arranged according to method actual detected of the present invention.
Get an amount of (about 50 μ l) testing sample, and detect after the liquor equal-volume mixes mutually at the end, draw the solution 50 μ l that mix, drip and detect that (detected parameters: constant potential is-1.2V on the screen printing electrode surface with pipettor; Be 100 seconds detection time).
The correction of testing result: the standard substance (interior mark ion) that adds concentration known (Amol/L), it detects gained concentration is B mol/L, the test substance detectable concentration is C mol/L, with the data substitution updating formula T=A * C/B mol/L that records, promptly obtain the actual concentration of required tested ion.
In the present embodiment, the ion concentration of mercury of adding is 10 μ g/L, and its detectable concentration is 11.2 μ g/L, and lead ion detectable concentration to be measured is 2.80 μ M, by formula calculates the actual concentration T=10*2.80/11.2 μ M that learns lead ion, promptly is about 2.5 μ M.
As can be seen from the results, use of the present invention improving one's methods, after proofreading and correct through the peak current of interior mark ion, the experimental data that finally obtains has significantly improved the accuracy (referring to Fig. 7) of voltammetry testing result.
Embodiment 2: detect the copper ion in the water sample
Use the detection method that the present invention narrated, at first preparation determines to contain the water sample of acetate in minute copper (0.5 μ M) as solution to be measured.Detecting end liquor is the 0.2M acetate buffer (pH=3.4) that contains 10 μ g/L mercuric nitrates.With this aqueous solution is detected object.
Get an amount of (about 50 μ l) testing sample, and detect after the liquid equal-volume mixes mutually at the end, draw gained mixed solution 50 μ l, drip and detect that (detected parameters is: constant potential is-1.0V on the screen printing electrode surface with pipettor; Be 100 seconds detection time).
The correction of testing result: the standard substance (interior mark ion) that adds concentration known (Amol/L), it detects gained concentration is B mol/L, the test substance detectable concentration is C mol/L, with the data substitution updating formula T=A * C/B (mol/L) that records, promptly obtain the actual concentration of required tested ion.
In the present embodiment, the ion concentration of mercury of adding is 10 μ g/L, and its detectable concentration is 9.1 μ g/L, and copper ion detectable concentration to be measured is 0.45 μ M, then by formula calculates the actual concentration T=10 * 0.45/9.1 μ M that learns copper ion, promptly is about 0.5 μ M.
Embodiment 3: detect the cadmium ion in the water sample
Use the detection method that the present invention narrated, preparation in advance determines to contain the water sample of acetate in minute cadmium (1 μ M) as solution to be measured.Detecting end liquor is the 0.2M acetate buffer (pH=3.4) that contains 10 μ g/L mercuric nitrates.With this water sample is detected object.
Get an amount of (about 50 μ l) testing sample, and detect after the liquid equal-volume mixes mutually at the end, draw mixed solution 50 μ l, drip and detect that (detected parameters: constant potential is-1.3V on the screen printing electrode surface with pipettor; Be 100 seconds detection time).
The correction of testing result: add the standard substance (interior mark ion) of concentration known (Amol/L), it detects gained concentration is B mol/L; The test substance detectable concentration is C mol/L, with the data substitution updating formula T=A * C/B (mol/L) that records, promptly obtains the actual concentration of required tested ion.
In the present embodiment, the ion concentration of mercury of adding is 10 μ g/L, and its detectable concentration is 13 μ g/L, and cadmium ion detectable concentration to be measured is 1.3 μ M, then by formula calculates the actual concentration T=10 * 1/13 μ M that learns cadmium ion, promptly is about 1 μ M.
Claims (6)
1. improve the method for the detection degree of accuracy of electrochemical activity metallic ion, in reaction system standard add have electroactive another kind of in standard gold belong to ion, detect the resulting data of concentration of metal ions to proofread and correct, thereby improve Electrochemical Detection result's accuracy with electrochemical detection method.
2. according to the process of claim 1 wherein that said electrochemical detection method is a voltammetry.
3. according to the process of claim 1 wherein that said metallic ion to be checked is the metallic ion with electrochemical activity.
4. according to the process of claim 1 wherein that said correction is meant the correction of carrying out according to the signal of interior mark ion and the mathematical relation of the signal that detects object ion.
5. according to the process of claim 1 wherein that employed detecting electrode is selected from screen printing electrode, metal film electrode, glass carbon normal electrode, goldstandard electrode, platinum normal electrode, and any type of modified electrode.
6. according to the process of claim 1 wherein that said interior mark ion not only includes the metallic ion of electrochemical activity, also comprises the organic and inorganic molecule that other have electrochemical activity simultaneously.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102628798A (en) * | 2012-04-24 | 2012-08-08 | 广州盈思传感科技有限公司 | ESPR-based heavy metal analyzer and analysis method thereof |
| CN103913502A (en) * | 2012-12-31 | 2014-07-09 | 北京师范大学 | Copper rapid determination method based on square-wave stripping voltammetry and three-electrode sensor |
| CN104807989A (en) * | 2015-05-04 | 2015-07-29 | 上海理工大学 | Dissociation and application of aptamer-mercury ion compound |
| CN105466982A (en) * | 2015-12-31 | 2016-04-06 | 聚光科技(杭州)股份有限公司 | Method for detecting heavy metal in water |
-
2009
- 2009-07-15 CN CN2009101581699A patent/CN101957336A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102628798A (en) * | 2012-04-24 | 2012-08-08 | 广州盈思传感科技有限公司 | ESPR-based heavy metal analyzer and analysis method thereof |
| CN103913502A (en) * | 2012-12-31 | 2014-07-09 | 北京师范大学 | Copper rapid determination method based on square-wave stripping voltammetry and three-electrode sensor |
| CN104807989A (en) * | 2015-05-04 | 2015-07-29 | 上海理工大学 | Dissociation and application of aptamer-mercury ion compound |
| CN104807989B (en) * | 2015-05-04 | 2016-08-31 | 上海理工大学 | The dissociating and applying of aptamer-mercury ion complex |
| CN105466982A (en) * | 2015-12-31 | 2016-04-06 | 聚光科技(杭州)股份有限公司 | Method for detecting heavy metal in water |
| CN105466982B (en) * | 2015-12-31 | 2019-02-05 | 聚光科技(杭州)股份有限公司 | Heavy metal detection method in water |
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Application publication date: 20110126 |