CN118150500A - Pretreatment and detection method for determining trace metal elements in seawater - Google Patents
Pretreatment and detection method for determining trace metal elements in seawater Download PDFInfo
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- 239000013535 sea water Substances 0.000 title claims abstract description 61
- 238000002203 pretreatment Methods 0.000 title claims abstract description 33
- 238000001514 detection method Methods 0.000 title claims abstract description 29
- 229910021654 trace metal Inorganic materials 0.000 title claims abstract description 18
- 239000000523 sample Substances 0.000 claims abstract description 72
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 46
- 238000000034 method Methods 0.000 claims abstract description 35
- 238000000605 extraction Methods 0.000 claims abstract description 30
- 238000011088 calibration curve Methods 0.000 claims abstract description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000010949 copper Substances 0.000 claims abstract description 26
- 229910052802 copper Inorganic materials 0.000 claims abstract description 25
- 239000011701 zinc Substances 0.000 claims abstract description 24
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052793 cadmium Inorganic materials 0.000 claims abstract description 23
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 23
- 239000013062 quality control Sample Substances 0.000 claims abstract description 22
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 20
- 238000010521 absorption reaction Methods 0.000 claims abstract description 16
- 239000012496 blank sample Substances 0.000 claims abstract description 16
- 239000007853 buffer solution Substances 0.000 claims abstract description 14
- 239000012074 organic phase Substances 0.000 claims abstract description 12
- 239000012071 phase Substances 0.000 claims abstract description 12
- 239000002904 solvent Substances 0.000 claims abstract description 11
- 239000002253 acid Substances 0.000 claims abstract description 9
- 239000002738 chelating agent Substances 0.000 claims abstract description 8
- 230000001105 regulatory effect Effects 0.000 claims abstract description 7
- 238000003908 quality control method Methods 0.000 claims abstract description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 17
- 229910017604 nitric acid Inorganic materials 0.000 claims description 17
- 239000000243 solution Substances 0.000 claims description 13
- IOEJYZSZYUROLN-UHFFFAOYSA-M Sodium diethyldithiocarbamate Chemical compound [Na+].CCN(CC)C([S-])=S IOEJYZSZYUROLN-UHFFFAOYSA-M 0.000 claims description 10
- DKPFZGUDAPQIHT-UHFFFAOYSA-N Butyl acetate Natural products CCCCOC(C)=O DKPFZGUDAPQIHT-UHFFFAOYSA-N 0.000 claims description 9
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical group CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 claims description 9
- MDDIUTVUBYEEEM-UHFFFAOYSA-N azane;pyrrolidine-1-carbodithioic acid Chemical compound N.SC(=S)N1CCCC1 MDDIUTVUBYEEEM-UHFFFAOYSA-N 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 6
- 239000012528 membrane Substances 0.000 claims description 6
- 239000000872 buffer Substances 0.000 claims description 4
- ZPWVASYFFYYZEW-UHFFFAOYSA-L dipotassium hydrogen phosphate Chemical compound [K+].[K+].OP([O-])([O-])=O ZPWVASYFFYYZEW-UHFFFAOYSA-L 0.000 claims description 4
- 229940111685 dibasic potassium phosphate Drugs 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 239000008057 potassium phosphate buffer Substances 0.000 claims description 3
- 229910021642 ultra pure water Inorganic materials 0.000 claims description 3
- 239000012498 ultrapure water Substances 0.000 claims description 3
- 241001089723 Metaphycus omega Species 0.000 claims description 2
- -1 ammonium pyrrolidinedicarboxylate Chemical compound 0.000 claims description 2
- 229910000396 dipotassium phosphate Inorganic materials 0.000 claims description 2
- 235000019797 dipotassium phosphate Nutrition 0.000 claims description 2
- 238000010979 pH adjustment Methods 0.000 claims 2
- 238000002360 preparation method Methods 0.000 abstract description 6
- 238000005259 measurement Methods 0.000 description 16
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000008055 phosphate buffer solution Substances 0.000 description 7
- 230000009286 beneficial effect Effects 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- 239000012086 standard solution Substances 0.000 description 6
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 description 5
- 239000005695 Ammonium acetate Substances 0.000 description 5
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 5
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 5
- 229940043376 ammonium acetate Drugs 0.000 description 5
- 235000019257 ammonium acetate Nutrition 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000012544 monitoring process Methods 0.000 description 5
- 239000011159 matrix material Substances 0.000 description 4
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 235000019796 monopotassium phosphate Nutrition 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- SPOMEWBVWWDQBC-UHFFFAOYSA-K tripotassium;dihydrogen phosphate;hydrogen phosphate Chemical compound [K+].[K+].[K+].OP(O)([O-])=O.OP([O-])([O-])=O SPOMEWBVWWDQBC-UHFFFAOYSA-K 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 206010070834 Sensitisation Diseases 0.000 description 2
- 238000002835 absorbance Methods 0.000 description 2
- 239000008346 aqueous phase Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000032798 delamination Effects 0.000 description 2
- 231100000053 low toxicity Toxicity 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910000402 monopotassium phosphate Inorganic materials 0.000 description 2
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 description 2
- 239000013558 reference substance Substances 0.000 description 2
- 239000012488 sample solution Substances 0.000 description 2
- 230000008313 sensitization Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 231100000419 toxicity Toxicity 0.000 description 2
- 230000001988 toxicity Effects 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- BICOYIUINQCUSU-UHFFFAOYSA-J P(=O)(O)([O-])[O-].[K+].[K+].[K+].[K+].P(=O)(O)([O-])[O-] Chemical compound P(=O)(O)([O-])[O-].[K+].[K+].[K+].[K+].P(=O)(O)([O-])[O-] BICOYIUINQCUSU-UHFFFAOYSA-J 0.000 description 1
- CXDFMHMOTQWHKT-UHFFFAOYSA-N [NH4+].[S-]C=S.C1CCNC1 Chemical compound [NH4+].[S-]C=S.C1CCNC1 CXDFMHMOTQWHKT-UHFFFAOYSA-N 0.000 description 1
- 229920006221 acetate fiber Polymers 0.000 description 1
- 239000013522 chelant Substances 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 125000004177 diethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229940111688 monobasic potassium phosphate Drugs 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000029219 regulation of pH Effects 0.000 description 1
- 230000007363 regulatory process Effects 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- QZNVHCWSDFYKTO-UHFFFAOYSA-M sodium;methanedithioate Chemical compound [Na+].[S-]C=S QZNVHCWSDFYKTO-UHFFFAOYSA-M 0.000 description 1
- 238000011895 specific detection Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
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- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Sampling And Sample Adjustment (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The application relates to the field of seawater detection, and particularly discloses a pretreatment and detection method for determining trace metal elements in seawater. The pretreatment method of the application comprises the following steps: (1) preparation of a seawater sample to be measured: collecting seawater filtered sample in a separating funnel, adding buffer solution, chelating agent and extraction solvent, shaking for extraction, collecting organic phase, adding acid for back extraction, collecting inorganic phase and purifying water to constant volume; (2) Preparing a calibration curve, a quality control sample and a blank sample to be tested: preparing a curve series, quality control samples and blanks in a separating funnel, regulating the pH value, adding buffer solution, chelating agent and extraction solvent, shaking for extraction, collecting an organic phase, adding acid for back extraction, collecting an inorganic phase and purifying water to fix the volume; trace metal elements are copper, lead, cadmium, nickel and zinc. The detection method of the application comprises the following steps: preparing each sample by a pretreatment method, and measuring each prepared sample to be tested by an atomic absorption method. The pretreatment and detection method provided by the application is simple to operate and high in detection accuracy.
Description
Technical Field
The application relates to the field of seawater detection, in particular to a pretreatment and detection method for determining trace metal elements in seawater.
Background
At present, copper, lead, cadmium, nickel and zinc in natural seawater are measured mainly by adopting an atomic absorption method in GB17378.4-2007 ocean monitoring Specification, wherein the copper, lead, cadmium and nickel adopt a flameless atomic absorption method, and the zinc adopts a flame atomic absorption method.
The content of copper, lead, cadmium, nickel and zinc in the natural seawater is particularly low, and the salinity of the seawater is high; when the atomic absorption method is adopted for measurement, the high salinity of the seawater can bring serious measurement interference and cannot be directly measured, so that the seawater sample is required to be pretreated to remove a salinity matrix and enrich low-concentration elements, thereby realizing accurate measurement.
However, the atomic absorption method measurement in GB17378.4-2007 "ocean monitoring Specification" has at least the following problems: first, the pretreatment methods for measuring copper, lead, and cadmium by a flameless atomic absorption method, for measuring nickel by a flameless atomic absorption method, and for measuring zinc by a flame atomic absorption method are different. Because the pretreatment method is not uniform, when the content of copper, lead, cadmium, nickel and zinc in natural seawater is required to be measured simultaneously, at least 3 pretreatment operations are required to be carried out to finish the preparation of the samples to be measured of the 5 metal elements, and when the content of copper, lead, cadmium, nickel and zinc is measured, the samples are required to be respectively sampled and put on a machine, so that repeated labor is caused, the detection efficiency is low, and the development of actual detection work is not facilitated.
Secondly, when copper, lead, cadmium and zinc are measured by adopting an atomic absorption method in GB17378.4-2007 ocean monitoring Specification, the prepared sample solution to be measured is an organic phase, and the sample solution to be measured in the organic phase is easy to volatilize, and chelate is easy to decompose and difficult to store stably for a long time, so that the sample injection precision is poor, and the accurate measurement is not facilitated.
Thirdly, methyl isobutyl ketone (MIBK) is adopted as an extraction solvent in GB17378.4-2007 ocean monitoring Specification and related data literature, ammonium acetate is adopted as a buffer solution, the MIBK is toxic, the water solubility is large and is not beneficial to extraction, an acetic acid matrix is easy to influence the sample transmission efficiency, a sensitization phenomenon exists in the measurement, and in addition, the ammonium acetate buffer solution is unstable and is easy to volatilize; both of these reasons are disadvantageous for accurate determination.
Therefore, it is necessary to provide a pretreatment and detection method for measuring trace metal elements in seawater, which is convenient and quick to operate and has high measurement accuracy, so as to be suitable for measuring trace copper, lead, cadmium, nickel and zinc in seawater by an atomic absorption method.
Disclosure of Invention
In order to solve the problems of complicated measuring process, environmental protection and inaccurate measuring result of the existing atomic absorption method, the application provides a pretreatment and detection method for measuring trace metal elements in seawater, which is convenient and quick to operate and has higher measuring precision.
Terminology in relation to the application
Nitric acid: ρ=1.42 g/L, superior purity and above.
Nitric acid solution (1+1): the water-based high-purity nitric acid is prepared by mixing 1 volume of water and 1 volume of nitric acid according to rho=1.42 g/mL of nitric acid, and superior purity and above.
And (3) quality control sample: cu, ni, pb, cd, zn units are standard solutions, or GBW (E) 080040.
The quality control sample is mainly used for verifying accuracy; since GBW (E) 080040 does not contain Ni, it is necessary to verify accuracy by measuring the labeled recovery rate of Ni using a Ni-element-proving standard solution as a quality control sample at the time of accuracy measurement.
Blank: pure water.
In a first aspect, the application provides a pretreatment method for determining trace metal elements in seawater, which adopts the following technical scheme:
A pretreatment method for determining trace metal elements in seawater, comprising the steps of:
Preparing a seawater sample to be tested: taking a natural seawater filtering sample in a separating funnel, adding a buffer solution, a chelating agent and an extraction solvent, carrying out shaking extraction, then collecting an organic phase, adding acid for back extraction, standing for layering, collecting an inorganic phase, and using pure water for constant volume;
Preparing a to-be-tested sample of a calibration curve sample, a quality control sample and a blank sample: preparing curve series, quality control samples and blank samples in different separating funnels respectively, regulating pH, adding buffer solution, chelating agent and extraction solvent, shaking for extraction, then collecting organic phase, adding acid for back extraction, standing for layering, collecting inorganic phase and using pure water for volume fixation;
The trace metal elements are copper, lead, cadmium, nickel and zinc;
The buffer was a monobasic potassium phosphate-dibasic potassium phosphate buffer at ph=8.0.
By adopting the technical scheme, the pH of the natural seawater sample is kept to be about 8.0 under the buffer action of the buffer solution due to the adoption of the specific phosphate buffer solution, the pH of the natural seawater sample does not need to be additionally regulated, and only the pH of the calibration curve sample, the quality control sample and the blank sample needs to be regulated to be 8.0, so that the operation procedure is simplified, and the risk of sample pollution in the pH regulation process is reduced.
Because the phosphate buffer solution is used for replacing the ammonium acetate buffer solution, the defects that the acetic acid matrix is easy to influence the sample transmission efficiency, the sensitization phenomenon exists in the measurement, and the ammonium acetate buffer solution is unstable and easy to volatilize, which is unfavorable for accurate measurement are overcome, so that the measurement result is more accurate.
The prepared sample to be tested is an aqueous solution, so that the sample can be stored more stably, and the sample injection precision is higher. And the sampling amount can be increased or the volume of the constant volume can be reduced appropriately according to the working requirement, so that the enrichment multiple of the seawater sample is higher, the enrichment of about 20-40 times can be achieved, and the method is more beneficial to the determination of low-concentration elements.
The pretreatment method only needs to carry out one-time pretreatment on the seawater sample to be tested, thereby realizing the one-time pretreatment of 5 metal elements of copper, lead, cadmium, nickel and zinc, simplifying the operation procedures and improving the detection efficiency.
Preferably, the extraction solvent is butyl acetate.
By adopting butyl acetate to replace traditional methyl isobutyl ketone (MIBK) as an extraction solvent, the ethyl acetate has lower toxicity and water solubility, thus being more beneficial to extraction and having low toxicity and environmental protection.
Preferably, the chelating agent is a mixture (1% +1%) of ammonium pyrrolidinedicarboxylate APDC and sodium diethylaminodithioformate DDTC.
Preferably, the pH is adjusted to pH 8.0.
Preferably, the acid in the acid stripping is a nitric acid solution (1+1).
Preferably, the seawater filtration sample is natural seawater with pH of 7.5-8.5 filtered by a 0.45 μm filter membrane. More preferably, the 0.45um filter membrane is a acetate membrane.
The filter membrane is adopted for filtering, so that microorganisms, particle impurities, colloid impurities, suspended matter impurities and the like contained in the seawater can be removed, and the influence on trace metal elements and the damage on a detection instrument are reduced.
Preferably, pure water refers to freshly prepared ultrapure water having a resistivity of 18.2 M.OMEGA.cm or more at 25 ℃.
By using ultrapure water, the influence of the metal element contained in water on the measurement result can be reduced, and the detection accuracy can be improved.
In a second aspect, the application provides a detection method for determining trace metal elements in seawater, which adopts the following technical scheme:
a detection method for determining trace metal elements in seawater, comprising the following steps:
(1) Preparing a seawater sample to be measured, a calibration curve sample, a quality control sample and a blank sample
Preparing a seawater sample to be tested, a calibration curve sample, a quality control sample and a blank sample to be tested by adopting the pretreatment method;
(2) Drawing a calibration curve
Using the calibration curve sample prepared in the step (1), wherein the curve series at least comprises 5 concentration points, measuring by an atomic absorption method, and drawing a calibration curve;
(3) Detection of
And (3) measuring each sample to be measured except for the calibration curve prepared in the step (1) by adopting an atomic absorption method.
Preferably, the copper, lead, cadmium and nickel in the sample to be measured are measured by a flameless method, and the zinc in the sample to be measured is measured by a flame method.
By adopting the technical scheme, the pretreatment method realizes the one-time pretreatment of 5 metal elements of copper, lead, cadmium, nickel and zinc, and only needs to sample once when measuring the copper, lead, cadmium and nickel, thereby simplifying the operation procedure.
In summary, the application has the following beneficial effects:
1. According to the pretreatment method, the specific phosphate buffer solution is adopted, so that the pH value of the natural seawater sample is kept to be about 8.0 under the buffer action of the buffer solution, the pH value of the natural seawater sample does not need to be additionally regulated, the pH value of each concentration point, quality control sample and blank sample of the calibration curve is regulated to be 8.0, the operation procedure is simplified, and the risk of sample pollution in the pH value regulating process is reduced.
2. According to the pretreatment method, the prepared sample to be tested is an aqueous solution, and can be stored more stably, so that the sample injection precision is higher, and accurate measurement is facilitated.
3. The pretreatment method of the application adopts butyl acetate with smaller water solubility and toxicity as an extraction solvent, thereby being beneficial to extraction and having low toxicity and environmental protection.
4. According to the pretreatment method, the phosphate buffer solution is adopted to replace the ammonium acetate buffer solution, so that the defects of an acetic acid matrix are overcome, and accurate determination is facilitated.
5. The pretreatment method only needs to carry out one-time pretreatment on the seawater sample to be tested, thereby realizing the one-time pretreatment of 5 metal elements of copper, lead, cadmium, nickel and zinc, simplifying the operation procedure and improving the detection efficiency.
6. The pretreatment method of the application can properly increase the sampling amount or reduce the volume of the constant volume according to the working requirement, so that the enrichment multiple of the sea water sample is higher, the enrichment of about 20-40 times can be achieved, and the method is more beneficial to the determination of low concentration elements.
7. The detection method of the application realizes the one-time pretreatment of 5 metal elements of copper, lead, cadmium, nickel and zinc, and only needs to sample once when measuring copper, lead, cadmium and nickel, thereby simplifying the operation procedure and improving the detection efficiency.
Detailed Description
The application is further described in detail below with reference to the following examples, which are specifically described: the following examples, in which no specific conditions are noted, are conducted under conventional conditions or conditions recommended by the manufacturer, and the raw materials used in the following examples are commercially available from ordinary sources except for the specific descriptions.
Are commercially available in general:
ρ=1.00 mg/L, cu, ni, pb, cd and Zn unit are standard solutions;
Seawater evidence standard reference substances (copper, lead, cadmium, chromium, zinc): GBW (E) 080040.
Solution preparation
(1) Preparation of nitric acid solution (1+1)
The high-purity nitric acid is prepared by mixing 1 volume of water and 1 volume of nitric acid according to rho=1.42 g/mL of nitric acid and higher than that of the high-purity nitric acid.
(2) Formulation of monobasic potassium phosphate/dibasic potassium phosphate buffer solution at ph=8.0
5.59G of anhydrous dipotassium hydrogen phosphate and 0.41g of anhydrous potassium dihydrogen phosphate are weighed, dissolved by adding water, and the volume is fixed to 1000mL, thus obtaining the water-soluble potassium dihydrogen phosphate.
(3) Preparation of APDC/DDTC (1% +1%) mixed liquor
1.0G of pyrrolidine ammonium dithioformate APDC (C 5H12N2S2) and 1.0g of diethyl sodium dithioformate DDTC (C 5H10NS2 Na) are respectively weighed and dissolved in water, filtered by filter paper, diluted to 100mL, extracted and purified by butyl acetate for 3 times, 10.0mL each time, and the collected aqueous solution is effectively stored in a refrigerator within one week.
(4) Preparation of mixed Standard use solutions
Cu, ni, pb, cd, zn Unit certificate standard solutions (ρ=1.00 mg/L) of corresponding volumes were respectively removed in volumetric flasks, diluted to 100ml with 1% nitric acid, so that ρ (Cu) =200 μg/L, ρ (Ni) =200 μg/L, ρ (Pb) =50 μg/L, ρ (Cd) =10 μg/L, ρ (Zn) =500 μg/L in the mixed standard use solutions.
Example 1
A pretreatment method for determining trace metal elements in seawater, comprising the steps of:
1. preparing a seawater sample to be tested:
filtering natural seawater from east sea with 0.45 μm acetate fiber filter membrane to obtain natural seawater filter sample.
Accurately weighing 100.0mL of natural seawater filtering sample in a 150mL separating funnel with a plug, adding 8.0mL of dipotassium hydrogen phosphate-dipotassium hydrogen phosphate buffer solution with pH=8.0, 2.0mL of APDC/DDTC (1% +1%) mixed solution and 5.0mL of butyl acetate, shaking and extracting for 2min, standing and layering, discarding a water phase, collecting an organic phase and adding 0.4mL of nitric acid solution (1+1), shaking and back extracting for 1min, standing and layering, collecting an inorganic phase and fixing the volume to 5.00mL by pure water;
2. Preparing a calibration curve sample to be tested:
Taking 7 branches of 150ml of separating funnel with a plug, respectively adding 100.0ml of pure water for experiments, sequentially transferring 0ml,0.20ml,0.40ml,0.60ml,0.80ml,1.00ml and 1.40ml of mixed standard use solution, uniformly mixing, adjusting the pH to 8.0, adding 8.0ml of potassium dihydrogen phosphate-dipotassium hydrogen phosphate buffer solution with the pH of 8.0, adding 2.0ml of APDC/DDTC (1% +1%) mixed solution and 5.0ml of butyl acetate, shaking and extracting for 2min, standing and layering, removing the water phase, collecting the organic phase and adding 0.4ml of nitric acid solution (1+1), shaking and back extracting for 1min, standing and layering, collecting the inorganic phase and fixing the volume to 5.00ml by pure water.
3. Preparing a quality control sample to be tested:
100.0mL of pure water for experiments was added to 150mL of a separating funnel with a plug, 5.0mL of quality control sample 1 or 0.1mL of quality control sample 2 was added, the pH was adjusted to 8.0, 8.0mL of potassium dihydrogen phosphate-dipotassium phosphate buffer solution with pH=8.0, 2.0mL of APDC/DDTC (1% +1%) mixture and 5.0mL of butyl acetate were added, the extraction was shaken for 2min, the aqueous phase was discarded after the separation by standing, the organic phase was collected and 0.4mL of nitric acid solution (1+1) was added, the back extraction was shaken for 1min, the separation was allowed to stand, the inorganic phase was collected and the volume was fixed to 5.00mL with pure water.
Quality control sample 1 is GBW (E) 080040, and quality control sample 2 is Cu, ni, pb, cd and Zn unit cell evidence standard solution.
The quality control sample is used when verifying the accuracy of the detection result; since GBW (E) 080040 does not contain Ni, it is necessary to use a Ni element proof standard solution as a quality control sample to measure the labeled recovery rate of Ni to verify accuracy, and to measure the labeled recovery rate of other four elements at the same time.
4. Preparing a blank sample to be tested:
Blank pure water was added to a 150mL separating funnel with a plug, the pH was adjusted to 8.0, 8.0mL of potassium dihydrogen phosphate-dipotassium hydrogen phosphate buffer solution with ph=8.0, 2.0mL of APDC/DDTC (1% +1%) mixture and 5.0mL of butyl acetate were added, the mixture was extracted by shaking for 2min, the aqueous phase was discarded after standing and delamination, the organic phase was collected and 0.4mL of nitric acid solution (1+1) was added, the back extraction was performed by shaking for 1min, the delamination was left standing, the inorganic phase was collected and the volume was fixed to 5.00mL with pure water.
Example 2
A detection method for determining trace metal elements in seawater, comprising the following steps:
(1) Respectively preparing seawater to-be-detected samples, calibration curve samples, quality control samples and blank samples by adopting the method of the embodiment 1;
(2) Drawing a calibration curve and detecting (2.1) copper, lead, cadmium and nickel by a flameless (graphite furnace) method
Drawing a calibration curve: the sample to be measured of the calibration curve sample prepared in example 1 was removed in a sample cup (about 1 mL), each concentration point of the calibration curve was measured by sample injection according to the set instrument parameter conditions, and the calibration curve was drawn with the absorbance subtracted from the laboratory blank as the ordinate and the corresponding element content (μg/L) as the abscissa.
Sea water sample, quality control sample and blank sample determination: the sea water sample, quality control sample and blank sample prepared in example 1 were removed in a sample cup (about 1 mL), and the sample was sampled and measured according to the same conditions as the calibration curve sample.
(2.2) Flame method measurement of Zinc
Drawing a calibration curve: and (3) sampling according to the set instrument parameter conditions to determine each concentration point of the calibration curve, and drawing the calibration curve by taking absorbance subtracted from a blank of a laboratory as an ordinate and corresponding element content (mug/L) as an abscissa.
Sea water sample, quality control sample and blank sample determination: and (5) sample injection measurement is carried out according to the same conditions of the calibration curve sample.
The specific detection conditions are as follows:
Performance test
1. Precision of
Relative deviation of seawater parallel samples RD% = (a-B)/(a+b) ×100%.
Wherein: A. b is the value of 2 tests respectively.
TABLE 1 seawater parallel double sample determination results
2. Accuracy of
The accuracy is measured by 2 experiments, namely, the content of each metal element in a standard reference substance (copper, lead, cadmium, chromium and zinc) GBW (E) 080040 with evidence of seawater is measured; and secondly, measuring the standard adding recovery rate.
Wherein, the addition recovery (%) = (C2-C1)/C3 is 100%;
Wherein: c1 is the measured value of the seawater sample, C2 is the measured value of the standard sample, and C3 is the sample scalar.
TABLE 2 determination of seawater Standard substance
TABLE 3 results of measurement of recovery rate by adding a mark
As can be seen from tables 1-3, the pretreatment method and the detection method of the application have detection precision and accuracy which meet the requirements of ocean monitoring standards, so that the pretreatment method and the detection method are suitable for detecting trace copper, lead, cadmium, nickel and zinc in natural seawater.
The present embodiment is only for explanation of the present application and is not to be construed as limiting the present application, and modifications to the present embodiment, which may not creatively contribute to the present application as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present application.
Claims (9)
1. A pretreatment method for determining trace metal elements in seawater, comprising the steps of:
Preparing a seawater sample to be tested: taking a natural seawater filtering sample in a separating funnel, adding a buffer solution, a chelating agent and an extraction solvent, carrying out shaking extraction, then collecting an organic phase, adding acid for back extraction, standing for layering, collecting an inorganic phase, and using pure water for constant volume;
Preparing a to-be-tested sample of a calibration curve sample, a quality control sample and a blank sample: preparing curve series, quality control samples and blank samples in different separating funnels respectively, regulating pH, adding buffer solution, chelating agent and extraction solvent, shaking for extraction, then collecting organic phase, adding acid for back extraction, standing for layering, collecting inorganic phase and using pure water for volume fixation;
The trace metal elements are copper, lead, cadmium, nickel and zinc;
The buffer was a monobasic potassium phosphate-dibasic potassium phosphate buffer at ph=8.0.
2. The pretreatment method according to claim 1, wherein the extraction solvent is butyl acetate.
3. The pretreatment method according to claim 1 or 2, wherein the chelating agent is a mixed solution (1% + 1%) of ammonium pyrrolidinedicarboxylate APDC and sodium diethylaminodithioformate DDTC.
4. The pretreatment method according to claim 1, wherein the pH adjustment is pH adjustment to 8.0.
5. The pretreatment method according to claim 1, wherein the acid in the acid-added back extraction is a nitric acid solution (1+1).
6. The pretreatment method according to claim 1, wherein the seawater filter sample is natural seawater having a pH of 7.5 to 8.5 filtered through a 0.45 μm filter membrane.
7. The pretreatment method according to claim 1, wherein the pure water is freshly prepared ultrapure water having a resistivity of at least 18.2 M.OMEGA.cm at 25 ℃.
8. A detection method for determining trace metal elements in seawater is characterized by comprising the following steps of: the method comprises the following steps:
(1) Preparing a seawater sample to be measured, a calibration curve sample, a quality control sample and a blank sample
Preparing a seawater sample to be tested, a calibration curve sample, a quality control sample and a blank sample to be tested by adopting the pretreatment method of any one of claims 1 to 7;
(2) Drawing a calibration curve
Using the calibration curve sample prepared in the step (1), wherein the curve series at least comprises 5 concentration points, measuring by an atomic absorption method, and drawing a calibration curve;
(3) Detection of
And (3) measuring each sample to be measured except for the calibration curve prepared in the step (1) by adopting an atomic absorption method.
9. The method of detecting according to claim 8, wherein: and measuring copper, lead, cadmium and nickel in the sample to be measured by adopting a flameless method, and measuring zinc in the sample to be measured by adopting a flame method.
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