CN104198412A - Method for detecting trace zinc ions by using cloud point extraction and ultraviolet-visible spectrophotometry - Google Patents
Method for detecting trace zinc ions by using cloud point extraction and ultraviolet-visible spectrophotometry Download PDFInfo
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- CN104198412A CN104198412A CN201410449233.XA CN201410449233A CN104198412A CN 104198412 A CN104198412 A CN 104198412A CN 201410449233 A CN201410449233 A CN 201410449233A CN 104198412 A CN104198412 A CN 104198412A
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Abstract
The invention discloses a method for detecting trace zinc ions by using cloud point extraction and ultraviolet-visible spectrophotometry. The method comprises the following steps: adding a sample to be detected to a cloud point extraction system containing an NH4Cl-NH3.H2O buffer solution with pH of 8.5, 1-(2-pyridylazo)-2-naphthol, TritonX-100, SDS (Sodium Dodecyl Sulfonate) and saturated sodium chloride NaCl; uniformly mixing and putting the mixture in a refrigerator to balance; and separating two phases by centrifuging, collecting a lower phase, diluting by using absolute ethyl alcohol and detecting the content of the zinc ions by ultraviolet-visible spectrophotometry, wherein the absorption wavelength of the spectrophotometry is 549nm. The method can be used for detecting trace zinc ions in environmental water samples and soil; the detection limit of the zinc ions is 3.3ng.mL<-1>; the enrichment factor is 38; the relative standard deviation is 2.8%; the adding standard recovery rate is 97.7%-101.5%.
Description
Technical field
The present invention relates to measure the method for trace metal ion, be specifically related to the method that a kind of cloud point extraction-ultraviolet-visible spectrophotometry is measured trace zinc ion.
Background technology
Zinc plays an important role for the generation of enzyme.Zinc is very important in immune system, digestive system, neural function, at some Zinc in Foods, is also very important.A large amount of zinc metalloenzymes is used in all metabolism.Health lacks zinc can cause skin disease, and wound recovers slowly, taste and smell hypofunction, and easy infection, fecundity reduces, and child's poor growth is drowsiness, poor appetite and easily hair loss.Zinc be highly corrosion and be widely used as a kind of protective coating is in different products.U.S. environment protection mechanism (EPA) has announced the content of zinc in potable water and has been no more than 5mgL
-1.
In environmental sample, the mensuration of trace element is a very difficult analysis task, due to sample composition be complicated and the component concentration of surveying very low.Therefore need delicate detection technique and preenrichment technology.Traditional abstraction technique and other traditional separation method take time and effort, and in addition also need a large amount of highly purified organic solvents, and environment is caused to serious pollution.Cloud point extraction preenrichment technology can address these problems.Cloud-Point Extraction Technique is used hypotoxic surfactant to replace poisonous organic solvent.The method is a kind of chemical method of green.Generally, before application quantitative analysis tech is as flame atomic absorption spectrometry, inductively coupled plasma emission spectrography and spectrophotometric method, utilize the metallo-chelate of cloud point extraction method extraction trace.
Summary of the invention
The shortcoming that the object of the invention is to overcome prior art, with not enough, provides a kind of cloud point extraction-ultraviolet-visible spectrophotometry to measure the method for trace zinc ion.
Object of the present invention is achieved through the following technical solutions:
Cloud point extraction-ultraviolet-visible spectrophotometry is measured a method for trace zinc ion, comprises the steps: testing sample to be added to and to comprise NH
4cl-NH
3h
2in the using cloud point extraction system of O buffer solution, 1-(2-pyridylazo)-beta naphthal (PAN), TritonX-100, SDS and NaCl, after mixing, be placed in refrigerator balance; After balance finishes, by centrifugal, make two to be separated again, collect lower floor's phase, with after absolute ethyl alcohol dilution, by the content of Spectrophotometric Determination of Zinc ion.
Described NH
4cl-NH
3h
2the pH of O buffer solution is preferably 8.5; The NH of pH=8.5
4cl-NH
3h
2the final concentration of O buffer solution in using cloud point extraction system is preferably 4% (v/v).
The final concentration of described 1-(2-pyridylazo)-beta naphthal in using cloud point extraction system is preferably 5.6 * 10
-5molL
-1.
The final concentration of described TritonX-100 in using cloud point extraction system is preferably 0.4% (v/v).
The final concentration of described SDS in using cloud point extraction system is preferably 0.1% (w/w).
The final concentration of described NaCl in using cloud point extraction system is preferably 12% (v/v) by saturated NaCl solution, and 1mL using cloud point extraction system is containing the saturated NaCl solution of 0.12mL.
The temperature of described balance is preferably 0 ℃, and the time of balance is preferably 30min.
Described centrifugal condition is preferably the centrifugal 10min of 4000r/min.
The absorbing wavelength of described spectrophotometric method is preferably 549nm.
Preferably, the method that described cloud point extraction-ultraviolet-visible spectrophotometry is measured trace zinc ion comprises the steps: 1.0mL testing sample solution to join in 15mL centrifuge tube, adds successively the NH of 0.4mLpH=8.5
4cl-NH
3h
2o buffer solution, 0.14mL4.0 * 10
-3molL
-11-(2-pyridylazo)-beta naphthal, the TritonX-100 solution of 0.8mL5% (v/v), the SDS solution of 1.0mL1% (w/w).Then add the saturated NaCl solution of 1.2mL, it is muddy that whole system becomes at once.With redistilled water, be settled to 10mL, after mixing, be placed in refrigerator and keep 30min at 0 ℃, then rotating speed makes two to be separated at the centrifugal 10min of 4000r/min.Then by tipping, the main body water on upper strata is got rid of.In the surfactant enrichment phase of lower floor's small size, add absolute ethyl alcohol to be settled to 3.0mL and dilute, measure gained solution in the absorbance of 549nm.By the standard working curve of making, horizontal ordinate is Zn
2+concentration, ordinate is absorbance.According to absorbance, determine Zn
2+concentration.
The present invention has the following advantages and effect with respect to prior art tool:
It is few, simple to operate that the method that the present invention measures trace zinc ion has solvent load, and the used time is short, environmentally safe, the feature such as enrichment times is large, and detectability is low.Because operating conditions is can reach good effect under the cryogenic conditions of 0 ℃, for the metallo-chelate of thermal sensitivity, there is good protective effect.Therefore the percentage extraction of metallo-chelate is very high.
The detection limit of the inventive method zinc ion is 3.3ngmL
-1, enrichment times is 38, relative standard deviation is 2.8%; Measure the configuration metal ions Zn of trace in environmental water sample, soil sample, blood sample
2+resulting recovery of standard addition is between 97.7～101.5%.
Accompanying drawing explanation
Fig. 1 is the Zn of variable concentrations
2+the absorption curve figure of the metallo-chelate forming with PAN, a to f concentration be respectively 10,50,100,200,300,400ngmL
-1zn
2+.
Fig. 2 is that pH is to Zn
2+percentage extraction affect result figure.
Fig. 3 is that PAN consumption is to Zn
2+percentage extraction affect result figure.
Fig. 4 is that TritonX-100 concentration is to Zn
2+percentage extraction affect result figure.
Fig. 5 is that equilibration time is to Zn
2+percentage extraction affect result figure.
Fig. 6 is that SDS concentration is to Zn
2+percentage extraction affect result figure.
Fig. 7 is NH
4cl-NH
3h
2o damping fluid consumption is to Zn
2+percentage extraction affect result figure.
Fig. 8 is that centrifugation time is to Zn
2+percentage extraction affect result figure.
Fig. 9 is that saturated NaCl consumption is to Zn
2+percentage extraction affect result figure.
Embodiment
Below in conjunction with specific embodiment, the present invention is done to further detailed description.Should be understood that the following examples are only not used in and limit the scope of the invention for the present invention is described.
Embodiment 1 cloud point extraction-ultraviolet-visible spectrophotometry is measured the foundation of the method for trace zinc ion
1, instrument, reagent
(1) instrument: pHS-3C type Numerical pH-meter (Shanghai Ao Si Instrument Ltd.), CAV214C electronic balance (Shanghai Ao Haosi Instrument Ltd.), DL-360E type Ultrasonic Intelligent cleaning apparatus (Shanghai Zhi Xin Instrument Ltd.), UV2550 ultraviolet-visible pectrophotometer (Japanese Shimadzu company), TG6A hydro-extractor (Shanghai Lu Xiang instrument Instrument Ltd.), constant temperature blast drying oven (Shanghai new talent medicine equipment Manufacturing Co., Ltd), electric-heated thermostatic water bath (Beijing forever bright Medical Instruments factory).
(2) reagent: 1mgmL
-1zn
2+standard reserving solution wherein adds the dilute nitric acid solution of a certain amount of 2% (v/v), Zn
2+standard operation solution (5 μ gmL
-1) be by Zn
2+standard reserving solution dilute with water forms.1-(2-pyridylazo)-beta naphthal (PAN) (99%, Aladdin reagent company) is mixed with 4.0 * 10
-3molL
-1ethanolic solution.TritonX-100 (99%, Aladdin reagent company) is made into the aqueous solution of 5% (v/v).SDS (Chengdu Ke Long reagent company limited) is made into the aqueous solution that concentration is 1% (w/w).0.2molL
-1nH
4cl solution and 0.2molL
-1nH
3h
2o solution is made into the buffer solution of pH=8.5.Other reagent used are all to analyze pure level, and the water in experimentation is redistilled water.
2, test method and result
Test method: Zn
2+standard solution cloud point extraction and method for measuring
Get a certain amount of Zn
2+standard operation solution, in 15mL centrifuge tube, adds the NH of 0.4mLpH=8.5 successively
4cl-NH
3h
2o buffer solution, 0.14mL4.0 * 10
-3molL
-11-(2-pyridylazo)-beta naphthal (PAN), the TritonX-100 solution of 0.8mL5% (v/v), the SDS solution of 0.2mL1% (w/w).Then add the saturated NaCl solution of 1.5mL, it is muddy that whole system becomes at once.With redistilled water, be settled to 10mL, after mixing, be placed in refrigerator and keep 30min at about 0 ℃, then rotating speed makes two to be separated at the centrifugal 10min of 4000r/min.This reaction does not need ice bath, because the micellar phase of reaction system is comprised of SDS and TritonX-100 mixed surfactant is as extractant for this reason.Then by tipping, the main body water on upper strata is got rid of.In the surfactant enrichment phase of lower floor's small size, add absolute ethyl alcohol to be settled to 3.0mL and dilute, gained soln using ultraviolet-visible spectrophotometer is carried out to the mensuration of absorption curve or absorbance.
Take the method as basis, determine metal complex maximum absorption wavelength, and study the impacts of factor on cloud point extraction such as pH value, PAN consumption, TritonX-100 concentration, equilibration time, SDS concentration, damping fluid consumption, centrifugation time, saturated NaCl consumption, to draw the optimal conditions of cloud point extraction-ultraviolet-visible spectrophotometry mensuration trace zinc ion.
Result and discussion:
(1) metal complex maximum absorption wavelength determines
Because the uv-absorption maximum wavelength of the different metal chelate of complexing agent is also different.So in the optimizing process of experiment condition, first must determine the maximum absorption wavelength of metallo-chelate.
According to Zn
2+standard solution cloud point extraction and method for measuring, the Zn of mensuration variable concentrations
2+the absorption curve of the metallo-chelate forming with PAN, result as shown in Figure 1, result shows, in this experiment, the rich micellar phase of zinc ion is maximum in 549nm place absorbance, therefore, ensuing all spectrophotometries are all chosen in the absorbance (Abs.) that 549nm measures solution in measuring.
First get the Zn of ascending different volumes
2+standard operation solution, by Zn
2+cloud point extraction is carried out in standard solution cloud point extraction and method for measuring, then at 549nm place, measure respectively the absorbance that each dissolves, according to lambert-law of Beer, absorbance and concentration are proportional, take concentration as horizontal ordinate, absorbance is ordinate, draws out typical curve and can calculate regression equation.Then get solution to be measured and carry out by the same method cloud point extraction, at 549nm place, measure equally absorbance, according to regression equation and sampling amount, can calculate Zn in solution to be measured
2+content.
(2) impact of pH value on cloud point extraction
By cloud point extraction method, metallic ion is extracted, prerequisite is to need suitable complexing agent and metallic ion to form hydrophobic chelate.Then hydrophobicity chelate is extracted in surfactant enrichment phase, and percentage extraction is the Acidity of Aikalinity of solution while depending on chelate formation.Therefore, the formation of pH major effect chelate and then affect Zn
2+percentage extraction.
According to Zn
2+standard solution cloud point extraction and method for measuring, get 100ngmL
-1zn
2+standard solution carries out cloud point extraction, and 549nm carries out absorbance measurement as absorbing wavelength.By adjusting NH
4cl-NH
3h
2the pH of O buffer solution is 7～11, the impact of research pH value on percentage extraction.As shown in Figure 2, pH value is along with the increase of its value in 7～8.5 scopes for result, and when pH=8.5, percentage extraction reaches maximum.This is because Zn
2+must under alkali condition, generate stable complex compound with PAN; But under excessive alkali condition, metallic ion is easily hydrolyzed into metal hydroxides, so along with continuing to increase pH value, the percentage extraction of zinc ion is declining gradually.Therefore select pH=8.5 as optimal pH.
(3) impact of PAN consumption on cloud point extraction
Cloud point extraction method and flame atomic absorption spectrometry coupling, for measuring the metallic ion of trace, are mainly to select suitable complexing agent.
According to Zn
2+standard solution cloud point extraction and method for measuring, get 100ngmL
-1zn
2+standard solution carries out cloud point extraction, and 549nm carries out absorbance measurement as absorbing wavelength.By adjusting 4.0 * 10
-3molL
-1the volume of 1-(2-pyridylazo)-beta naphthal (PAN) be 0.06～0.20mL, the impact of research complexing agent concentration on zinc extraction yield.Result as shown in Figure 3, PAN volume within the scope of 0.06～0.14mL along with the increase of PAN concentration, Zn
2+percentage extraction increases gradually.This is because of the increase along with complexing agent consumption, and the amount of the chelate that metallic ion and complexing agent form is also in continuous increase, and then the metallic ion that is extracted to surfactant enrichment phase is constantly increasing, so Zn
2+percentage extraction is in continuous increase.When PAN volume is 0.14mL as shown in Figure 3, it is maximum that the recovery reaches.Continue to increase the consumption of PAN, its recovery is constantly declining.Because the hydrophobicity of complexing agent is more eager to excel in whatever one does than the hydrophobicity of corresponding metallo-chelate, excessive complexing agent cements out the metallic ion in metallo-chelate to enter main body water, and complexing agent can be by preferential being extracted in surfactant enrichment phase, so Zn
2+percentage extraction is constantly reducing.Therefore select 4.0 * 10
-3molL
-1pAN volume be that 0.14mL is as top condition.
(4) impact of TritonX-100 concentration on cloud point extraction
In cloud point extraction, TritonX-100 is a kind of comparatively general surfactant.Because this surfactant has highly purified industrial effect, low toxicity, low price, the advantage such as the low and density of cloud point temperature is large.Highdensity surfactant enrichment phase is conducive to the separation of phase.
According to Zn
2+standard solution cloud point extraction and method for measuring, get 100ngmL
-1zn
2+standard solution carries out cloud point extraction, and 549nm carries out absorbance measurement as absorbing wavelength.By adjusting the volume that adds of 5% (v/v) TritonX-100, controlling ultimate density is 0.1～0.7% (v/v), studied the impact of surfactant concentration on cloud point extraction, by control variable concentrations TritonX-100 (0.1～0.7%, v/v) to Zn
2+the impact of percentage extraction as shown in Figure 4.At the increase along with TritonX-100 concentration in 0.1～0.4% scope of TritonX-100 concentration, Zn
2+percentage extraction increases gradually, and this is that the amount that metallo-chelate is extracted in surfactant enrichment phase increases gradually because of the increasing along with dosage of surfactant.Surfactant phase volume is too little, is difficult to separation after extraction, and reappearance and accuracy reduce.When TritonX-100 concentration is 0.4% (v/v), Zn
2+the percentage extraction of percentage extraction is maximum, continues to increase TritonX-100 concentration, Zn
2+percentage extraction is substantially constant, because along with the continuation of Triton X-100 concentration increases, metallic ion is extracted completely.Dosage of surfactant is excessive, and phase volume ratio can reduce, and enrichment times reduces.Therefore select to add 0.8mL5% (v/v) TritonX-100, controlling its ultimate density is that 0.4% (v/v) is as top condition.
(5) impact of equilibration time on cloud point extraction
Equilibration time is very large on cloud point extraction impact.In order to reach complete cloud point extraction in shorter equilibration time, according to Zn2+ standard solution cloud point extraction and method for measuring, get 100ngmL
-1zn
2+standard solution carries out cloud point extraction, and 549nm carries out absorbance measurement as absorbing wavelength.It is 15-50min about the 0 ℃ time keeping that adjustment system is placed in refrigerator, the impact of research equilibration time on cloud point extraction.Result as shown in Figure 5, when equilibration time is 30min, Zn
2+percentage extraction reach maximum, the delay equilibration time of continuation, little on the impact of percentage extraction.Therefore, should be chosen in short as far as possible equilibration time and make Metal Zn
2+completely, selecting equilibration time is that 30min is as top condition in extraction.
(6) impact of SDS concentration on cloud point extraction
Experiment finds only to use TritonX-100 as the Zn of surfactant extraction trace
2+, its percentage extraction is very low, cloud point temperature is high.But add appropriate anionic surfactant SDS, can make the cloud point temperature of whole system decline, the metallic ion of trace can be extracted at ambient temperature.Because SDS is introduced in TritonX-100 solution, the cloud point temperature of solution drops to 0 ℃, only need to be placed in refrigerator and metallic ion can be extracted.
According to Zn
2+standard solution cloud point extraction and method for measuring, get 100ngmL
-1zn
2+standard solution carries out cloud point extraction, and 549nm carries out absorbance measurement as absorbing wavelength.It is 0.025-0.25% that the volume of adjustment 1%SDS solution makes the final concentration of SDS in system, the impact of research SDS concentration on cloud point extraction.Result as shown in Figure 6, when SDS mass concentration is 0.1%, Zn
2+percentage extraction reach maximum, continue to increase the concentration of SDS, little on the impact of percentage extraction.Therefore, should be chosen in a small amount of to the greatest extent use SDS and make Metal Zn
2+completely, selecting SDS mass concentration is 0.1% as optimum reaction condition in extraction.
(7) impact of damping fluid consumption on cloud point extraction
Damping fluid is very large on the impact of the metallo-chelate of metallic ion and complexing agent formation.Therefore, use as far as possible small amount damping fluid to make metallic ion extraction completely.According to Zn
2+standard solution cloud point extraction and method for measuring, get 100ngmL
-1zn
2+standard solution carries out cloud point extraction, and 549nm carries out absorbance measurement as absorbing wavelength.Adjust the NH of pH=8.5
4cl-NH
3h
2the volume of O buffer solution is 0.1-0.8mL, the impact of research damping fluid consumption on cloud point extraction.Result as shown in Figure 7, when damping fluid consumption is during 0.4mL, Zn
2+percentage extraction reach maximum, continue to increase the consumption of damping fluid, the percentage extraction of zinc ion remains unchanged substantially.Therefore, selecting damping fluid consumption is that 0.4mL is as optimum optimizing condition.
(8) impact of centrifugation time on cloud point extraction
In order to make solution be separated into fast two-phase, need to carry out centrifuging by external force.Along with the growth of centrifugation time, the percentage extraction of zinc ion increases gradually.When reaching maximal value, along with the lengthening of time, percentage extraction remains unchanged substantially.Because the cloud point temperature of mixed surfactant is 0 ℃ of left and right, therefore increase its percentage extraction of centrifugation time substantially constant.
According to Zn
2+standard solution cloud point extraction and method for measuring, get 100ngmL
-1zn
2+standard solution carries out cloud point extraction, and 549nm carries out absorbance measurement as absorbing wavelength.Adjustment system centrifugal time under 4000r/min rotating speed is 2-20min, the impact of research centrifugation time on cloud point extraction.Result as shown in Figure 8, when centrifugation time is 10min, Zn
2+percentage extraction reach maximum, continue to extend centrifugation time, the percentage extraction of zinc ion remains unchanged.Therefore, selecting centrifugation time is that 10min is as optimum optimizing condition.
(9) impact of saturated NaCl consumption on cloud point extraction
Generally, adjuvant is little on the impact of cloud point extraction, but a lot of adjuvant is very large as electrolyte and organism on the impact of percentage extraction, thereby because it affects very greatly the separation of phase to the impact of cloud point temperature.The cloud point temperature of TritonX-100 is 65 ℃, if add appropriate inorganic electrolyte solution as NaCl, it can make the hydrogen bond rupture of micellar phase, the material of hydrophobic grouping is separated from water and cloud point temperature has also reduced.
According to Zn
2+standard solution cloud point extraction and method for measuring, get 100ngmL
-1zn
2+standard solution carries out cloud point extraction, and 549nm carries out absorbance measurement as absorbing wavelength.The volume of adjusting saturated NaCl solution is 0.4-2.0mL, studies the impact of saturated NaCl consumption on cloud point extraction.Result is as Fig. 9, and along with the increase of NaCl consumption, percentage extraction is increase gradually, and when NaCl consumption is 1.2mL, it is maximum that percentage extraction reaches; Continue to increase NaCl consumption, Zn
2+the recovery decline gradually because along with the increasing of NaCl consumption, the density of solution increases gradually, surfactant can not contact with complex compound is large-area, surfactant swims in upper strata, is unfavorable for micellar phase extraction complex compound.Therefore, selecting NaCl consumption is that 1.2mL is as optimum optimizing condition.
The best approach that draws cloud point extraction-ultraviolet-visible spectrophotometry mensuration trace zinc ion by foregoing is: 1.0mL testing sample solution is joined in 15mL centrifuge tube, add successively the NH of 0.4mLpH=8.5
4cl-NH
3h
2o buffer solution, 0.14mL4.0 * 10
-3molL
-11-(2-pyridylazo)-beta naphthal (PAN), the TritonX-100 solution of 0.8mL5% (v/v), the SDS solution of 1.0mL1% (w/w).Then add the saturated NaCl solution of 1.2mL, it is muddy that whole system becomes at once.With redistilled water, be settled to 10mL, after mixing, be placed in refrigerator and keep 30min at about 0 ℃, then rotating speed makes two to be separated at the centrifugal 10min of 4000r/min.Then by tipping, the main body water on upper strata is got rid of.In the surfactant enrichment phase of lower floor's small size, add absolute ethyl alcohol to be settled to 3.0mL and dilute, measure gained solution in the absorbance of 549nm.By the standard working curve of making, horizontal ordinate is Zn
2+concentration, ordinate is absorbance.According to absorbance, determine Zn
2+concentration.
Described testing sample is pretreated sample, and sample comprises water sample, soil sample and blood sample; The preprocess method of each sample is as follows:
The pre-service of water sample: with membrane filtration river (Xihe River), river (Jia Lingjiang River), tap water (laboratory) sample in 0.45 μ m aperture, object is to remove the particulate suspending in water body, the aqueous solution refrigeration of handling well is standby.
The pre-service of soil sample:
Gather respectively the soil sample in mountain region, school district, garden and farmland.By air-dry, coarse crushing, then through four minutes division methods, the soil of collection is carried out to division, the pedotheque after division heats 24h until soil is dried in 120 ℃ of thermostatic drying chambers.By ceramic mortar, by soil porphyrize, choose the foreign material such as large rock mass and grass roots, then sieve with 100 order sub-sieves, the sample obtaining is used in order to analysis below.Before sample preparation, mortar, the instrument used such as sub-sieve will clean up with absolute ethyl alcohol, prevents that sample is contaminated, and the result of measuring is exerted an influence.
Take respectively the above-mentioned soil of 5.0g, add 50mL0.1molL
-1hydrochloric acid solution, the soaked overnight that stirs, constant temperature oscillation 3h in oscillator, standing filtration, it is standby that gained filtrate is pedotheque solution refrigeration.
The pre-service of blood sample: take the full rabbit blood sample of 5g in 100mL conical flask, add the dense HNO of 5mL
3soaked overnight, then add 2mL30%H
2o
2, conical flask is placed on temperature control heating plate and is cleared up to solution clear under 120 ℃ of conditions, continue heating and catch up with acid, until liquor capacity, during in 1mL left and right, conical flask is taken off, solution is settled to 50mL volumetric flask, refrigerate standby.
Further study the analytical performance of the method, got 10,40,200,500,1000ngmL
-1zn
2+standard solution, by cloud point extraction-ultraviolet-visible spectrophotometry, measure the best approach of trace zinc ion and carry out cloud point extraction, then at 549nm place, measure respectively the absorbance that each dissolves, the equation of linear regression calculating is A=0.00291C+0.001914 (R
2=0.9976), A represents absorbance, and C represents the concentration of zinc ion, and its range of linearity is 10～1000ngmL
-1, by the enrichment times of cloud point extraction method enrichment zinc ion, be 38.The detectability of this method (3 σ) is 3.3ngmL
-1, relative standard deviation (RSD) is 2.8% (Zn
2+mass concentration be 100ngmL
-1, n=11).
Embodiment 2 interfering ions are measured the impact of the method for trace zinc ion on cloud point extraction-ultraviolet-visible spectrophotometry
According to the method for embodiment 1, studied the impact of several frequently seen metallic ion on zinc ion percentage extraction, as shown in Table 1, the metallic ion in normal water sample, soil sample, blood sample does not produce interference to the percentage extraction of zinc ion to result substantially.
The impact of table 1 interfering ion on cloud point extraction
The mensuration of embodiment 3 samples
According to the method for embodiment 1 to tap water, river (Xihe River), river (Jia Lingjiang River), mountain soil, garden soil, farmland is native and rabbit blood sample in the zinc ion of trace measure.The results are shown in Table 2.The recovery of standard addition of sample is 97.7～101.5%.Therefore the zinc ion of trace in environmental water sample, soil is measured in available cloud point extraction method and ultraviolet spectrophotometry coupling.
The mensuration of zinc ion content (n=3) in table 2 sample
The present invention is usingd TritonX-100 and SDS as mixed surfactant, and 1-(2-pyridylazo)-beta naphthal (PAN) is as complexing of metal ion agent, cloud point extraction method and ultraviolet spectrophotometry coupling is measured to the Zn of trace
2+.Detailed discussion different reaction conditions impacts on zinc extraction yield as pH value, complexing agent consumption, surfactant concentration, equilibration time and equilibrium temperature etc., show that optimum cloud point extraction-ultraviolet-visible spectrophotometry measures the method for trace zinc ion.Under the method condition, the detection limit of zinc ion is 3.3ngmL
-1, enrichment times is 38, relative standard deviation is 2.8%; Measure the configuration metal ions Zn of trace in environmental water sample, soil sample, blood sample
2+resulting recovery of standard addition is between 97.7～101.5%.
Claims (10)
1. cloud point extraction-ultraviolet-visible spectrophotometry is measured a method for trace zinc ion, it is characterized in that comprising the steps: testing sample is added to and comprises NH
4cl-NH
3h
2in the using cloud point extraction system of O buffer solution, 1-(2-pyridylazo)-beta naphthal, TritonX-100, SDS and NaCl, after mixing, be placed in refrigerator balance; After balance finishes, by centrifugal, make two to be separated again, collect lower floor's phase, with after absolute ethyl alcohol dilution, by the content of Spectrophotometric Determination of Zinc ion.
2. the method for mensuration trace zinc ion according to claim 1, is characterized in that: described NH
4cl-NH
3h
2the pH of O buffer solution is 8.5; The NH of pH=8.5
4cl-NH
3h
2the final concentration of O buffer solution in using cloud point extraction system is 4% (v/v).
3. the method for mensuration trace zinc ion according to claim 1, is characterized in that: the final concentration of described 1-(2-pyridylazo)-beta naphthal in using cloud point extraction system is 5.6 * 10
-5molL
-1.
4. the method for mensuration trace zinc ion according to claim 1, is characterized in that: the final concentration of described TritonX-100 in using cloud point extraction system is 0.4% (v/v).
5. the method for mensuration trace zinc ion according to claim 1, is characterized in that: the final concentration of described SDS in using cloud point extraction system is 0.1% (w/w).
6. the method for mensuration trace zinc ion according to claim 1, is characterized in that: the final concentration of described NaCl in using cloud point extraction system counted 12% (v/v) by saturated NaCl solution.
7. the method for mensuration trace zinc ion according to claim 1, is characterized in that: the temperature of described balance is 0 ℃, and the time of balance is 30min.
8. the method for mensuration trace zinc ion according to claim 1, is characterized in that: described centrifugal condition is the centrifugal 10min of 4000r/min.
9. the method for mensuration trace zinc ion according to claim 1, is characterized in that: the absorbing wavelength of described spectrophotometric method is 549nm.
10. the method for mensuration trace zinc ion according to claim 1, is characterized in that comprising the steps: 1.0mL testing sample solution is joined in 15mL centrifuge tube, adds successively the NH of 0.4mLpH=8.5
4cl-NH
3h
2o buffer solution, 0.14mL4.0 * 10
-3molL
-11-(2-pyridylazo)-beta naphthal, the TritonX-100 solution of 0.8mL5% (v/v), the SDS solution of 1.0mL1% (w/w), then add the saturated NaCl solution of 1.2mL, with redistilled water, be settled to 10mL, after mixing, be placed in refrigerator and keep 30min at 0 ℃, then make two to be separated at the centrifugal 10min of 4000r/min; By tipping, the main body water on upper strata is got rid of, in the surfactant enrichment phase of lower floor's small size, added absolute ethyl alcohol to be settled to 3.0mL and dilute, measure gained solution in the absorbance of 549nm; By the standard working curve of making, horizontal ordinate is Zn
2+concentration, ordinate is absorbance, according to absorbance, determines Zn
2+concentration.
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| CN111579510A (en) * | 2020-05-29 | 2020-08-25 | 西安建筑科技大学 | Light sensing film and method for rapidly, quantitatively and selectively detecting Cd (II), Cu (II) and Zn (II) |
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