Rapid detection method for total arsenic in grains
By mixing the grain with the extractant and extracting it at 95-105°C, combined with purifier separation and screen-printed electrode detection, the problem of rapid, convenient and low-cost detection of total arsenic in grain is solved, and high accuracy and stability of high throughput screening is achieved.
Patent Information
- Application Number
- CN202510625217.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-15
- Publication Date
- 2025-08-12
AI Technical Summary
The prior art is difficult to achieve rapid, convenient and low-cost detection of total arsenic in food. Traditional methods have safety risks, high costs, complex operations and are not suitable for high-throughput screening.
The grain was mixed with the extractant and extractant was extracted at 95-105°C, and the mixture was separated from the purifier. The total arsenic was detected using screen printing electrodes and cathode dissolution voltammetry, including the use of precipitant and masking agents, and the pretreatment steps were simplified.
It realizes rapid detection of total arsenic in grain, completed within 30 minutes, has high detection accuracy, good stability and repeatability, and is suitable for high-throughput screening, low cost and wide application range.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of detection, and particularly relates to a rapid detection method for total arsenic in grains. Background Art
[0002] Arsenic is a common pollutant that poses a potential hazard to human health. Traditional methods for detecting arsenic include atomic absorption spectrometry, inductively coupled plasma mass spectrometry, and atomic fluorescence spectrometry. These traditional methods are supported by pretreatment methods such as wet digestion, microwave digestion, and dry ashing. Wet digestion is suitable for most samples and offers good versatility across different sample types. However, the digestion solution utilizes a large amount of strong acids and strong oxidants, such as nitric acid, perchloric acid, and sulfuric acid, which poses certain safety risks. The digestion process generates a large amount of waste gas, requiring effective tail gas treatment. Furthermore, residual acid may remain in the sample solution after digestion, requiring acid removal, otherwise it will interfere with subsequent analysis. Microwave digestion is fast, typically completing the digestion process in just tens of minutes. It also requires minimal reagent consumption, minimizing environmental pollution. The digestion temperature and pressure can be precisely controlled, effectively preventing the volatilization of heavy metal elements and cross-contamination of samples. However, microwave digestion equipment is expensive and operating costs are relatively high. For certain samples with high organic matter content, pretreatment or additional digestion steps may be required to ensure complete digestion of the sample. During microwave digestion, improper operation or uneven sample distribution may lead to safety issues such as local overheating or tank explosion. The dry ashing method does not require large amounts of chemical reagents and can effectively remove organic matter and reduce interference. The high temperature of dry ashing may lead to the loss of certain volatile heavy metal elements such as mercury and arsenic. The processing time is long, usually taking several hours or even longer. The sample may sinter or agglomerate, resulting in incomplete ashing.
[0003] Although classical arsenic detection methods such as atomic absorption spectroscopy, inductively coupled plasma mass spectrometry, and atomic fluorescence spectroscopy are highly accurate, they require specialized instruments and personnel to operate, and are characterized by long detection times, high costs, and complex operations. These methods are difficult to meet the requirements of high-throughput screening during grain harvesting or routine supervision. In recent years, the specific recognition of arsenic by biomolecules (such as enzymes, antibodies, and nucleic acids) has been exploited to convert biological reactions into detectable signals, promising on-site detection. The unique physical and chemical properties of nanomaterials (such as gold nanoparticles and carbon nanotubes) have been utilized to construct sensors with high sensitivity and selectivity for arsenic, providing greater potential for improving detection performance. At the current stage of rapid detection technology development, addressing the issues of rapid pretreatment of grain samples and developing convenient, low-cost methods for detecting arsenic in grain are key issues in achieving rapid detection of total arsenic in grain. Summary of the Invention
[0004] In order to overcome at least one technical problem existing in the above-mentioned prior art, one of the objectives of the present invention is to provide a method for extracting arsenic from food.
[0005] A second object of the present invention is to provide a method for detecting total arsenic in grain.
[0006] In order to achieve the above object, the technical solution adopted by the present invention is:
[0007] A first aspect of the present invention provides a method for extracting arsenic from grain, comprising the following steps:
[0008] The grain and the extractant are mixed and extracted at 95-105° C. to obtain a mixed solution;
[0009] mixing the mixed liquid with a purifier, and then performing solid-liquid separation to obtain an arsenic-containing extract;
[0010] The extractant includes an inorganic acid;
[0011] The purifying agent contains a precipitant and a masking agent;
[0012] The precipitant comprises at least one of zinc acetate, zinc sulfate, potassium ferrocyanide, ammonium sulfate, ammonium acetate, and trichloroacetic acid;
[0013] The masking agent includes at least one of thiourea, stannous chloride, sodium fluoride and sodium citrate.
[0014] In some embodiments of the present invention, the volume mass ratio of the extractant to the grain is (5-20) mL:1g; in some embodiments of the present invention, the volume mass ratio of the extractant to the grain is 5 mL:1g, 6 mL:1g, 7 mL:1g, 8 mL:1g, 9 mL:1g, 10 mL:1g, 11 mL:1g, 12 mL:1g, 13 mL:1g, 14 mL:1g, 15 mL:1g, 16 mL:1g, 17 mL:1g, 18 mL:1g, 19 mL:1g, 20 mL:1g, any one of the values or a range value formed by any two of them.
[0015] In some embodiments of the present invention, the food comprises rice, wheat, corn, or soybean.
[0016] In some embodiments of the present invention, the food is a crushed food powder. In some embodiments of the present invention, the food is a crushed food powder obtained by passing through a 100-mesh sieve.
[0017] In some embodiments of the present invention, the solid-liquid separation is performed by filtration or centrifugation to separate the solid and the liquid.
[0018] In some embodiments of the present invention, the centrifugal speed is 7000-10000 r / min.
[0019] In some embodiments of the present invention, the centrifugation time is 2 to 5 minutes.
[0020] In some embodiments of the present invention, the volume mass ratio of the purifier to the grain is (0.5-10) mL:1 g.
[0021] In some embodiments of the present invention, the extraction time is 5 to 15 minutes.
[0022] In some embodiments of the present invention, the volume ratio of the precipitant to the masking agent is (0.5-10):1.
[0023] In some embodiments of the present invention, the inorganic acid comprises at least one of HCl, HClO4, HNO3, and H2SO4.
[0024] A second aspect of the present invention provides a method for detecting total arsenic in grain, comprising the following steps:
[0025] The arsenic in the grain is extracted using the method for extracting total arsenic in grain according to the first aspect of the present invention to obtain an arsenic-containing extract;
[0026] Mixing the arsenic-containing extract with a modification solution to obtain a test solution;
[0027] Cathodic stripping voltammetry was used to detect the test solution using screen-printed electrodes, and the arsenic content in the grain was determined based on the standard curve.
[0028] The modification solution contains copper salt, mercury salt and potassium salt.
[0029] The working electrode and the counter electrode of the screen-printed electrode are both carbon electrodes, and the reference electrode is an Ag / AgCl electrode.
[0030] In some embodiments of the present invention, in the modification solution, the concentration of cuprous salt is 0.001-0.5 mol / L, the concentration of mercuric salt is 0.005-0.2 mol / L, and the volume of potassium salt is 0.02-1% of the volume of the modification solution.
[0031] In some embodiments of the present invention, the total arsenic in the grain includes organic arsenic in the grain and inorganic arsenic in the grain.
[0032] In some embodiments of the present invention, the enrichment potential of the detection is -1.1V to -0.8V.
[0033] In some embodiments of the present invention, the enrichment time of the detection is 120 to 240 s.
[0034] In some embodiments of the present invention, the detected dissolution potential is 0 to -1.0V.
[0035] In some embodiments of the present invention, the number of enrichment-dissolution cycles for the detection is 1-3 times.
[0036] In some embodiments of the present invention, the detection is performed using an electrochemical workstation or an electrochemical heavy metal detector.
[0037] In some embodiments of the present invention, the electrochemical heavy metal detector has built-in standard curve and temperature compensation parameters.
[0038] In some embodiments of the present invention, the volume ratio of the modifying solution to the test solution is (0.01-0.2):1.
[0039] The beneficial effects of the present invention are: the method for extracting arsenic from grains can quickly and efficiently extract total arsenic from grains and reduce macromolecules such as protein in the arsenic-containing extract; the extraction method is simple and easy to operate and can be completed without special equipment.
[0040] The detection method for total arsenic in grains of the present invention is simple and easy to operate. It can complete the detection of total arsenic in a single grain sample within 30 minutes, and the test results are highly accurate, with a low detection limit, good detection stability and repeatability. It can be used for high-throughput rapid screening in grain collection or daily supervision. In addition, the detection method of the present invention has a wide range of applications and can be applied to the rapid detection of total arsenic in grains such as rice, wheat, corn, and soybeans. It is fast, efficient, and low-cost, and does not require electrode modification before each test, which can avoid the tedious electrode modification process and the errors caused by it. It has broad application prospects in the rapid detection and monitoring of heavy metal arsenic in grains. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] Figure 1 Schematic diagram of the structure of the screen-printed electrodes used in Examples 1 to 3 and Comparative Example 1.
[0042] Figure 2 The figure is a standard curve obtained by the test method in Example 1.
[0043] Figure 3 The stripping voltammetry curves of samples with different concentrations measured using the test method in Example 2 are shown. DETAILED DESCRIPTION
[0044] The specific implementation of the present invention will be further described in detail below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are any processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be purchased commercially.
[0045] The schematic structural diagram of the screen-printed electrodes used in Examples 1 to 3 of the present invention and Comparative Example 1 is shown in FIG. Figure 1 shown.
[0046] Example 1
[0047] This example provides a method for detecting total arsenic in grain. The method includes three aspects: sample extraction, sample purification, and total arsenic testing in grain. Specifically, the method includes the following steps:
[0048] Step 1: Extraction of total arsenic in grain samples:
[0049] 1g of grain sample was crushed and passed through a 100-mesh sieve, then mixed with the extractant at a liquid-solid ratio of 10mL:1g of extractant to grain sample. After mixing, the mixture was placed in a boiling water bath for 15min.
[0050] The extractant is a mixture of 5 mL of a 1 mol / L hydrochloric acid solution and 5 mL of a 0.5 mol / L perchloric acid solution.
[0051] Step 2: Sample purification:
[0052] Add a scavenger to the solution after the boiling water bath in step 1. The scavenger is obtained by mixing 3 mL of 5% zinc sulfate solution, 1 mL of 1% thiourea solution, and 1 mL of 0.01% stannous chloride solution. Shake well and centrifuge at 8000 rpm for 5 minutes.
[0053] Step 3: Total Arsenic Testing:
[0054] Take 4 mL of the supernatant from the centrifugation in step 2, add 0.2 mL of 0.01 mol / L CuCl, 0.2 mL of 0.1% KI solution, and 0.2 mL of 0.05 mol / L Hg(NO₃)₂, and mix vigorously to obtain the test solution. Use a portable electrochemical heavy metal detector equipped with screen-printed electrodes, select the "Arsenic in Grain" test, and click the "Start Test" button to begin the test.
[0055] The screen-printed electrodes were: a circular carbon working electrode, a square carbon counter electrode, and a square Ag / AgCl reference electrode. The portable electrochemical heavy metal analyzer test program parameters were set as follows: square wave stripping voltammetry, an accumulation potential of -1.0 V, a rotational accumulation time of 120 s, a stripping potential of 0 to -1.0 V, three accumulation and stripping cycles, and the final signal was used.
[0056] Rice samples confirmed as negative by the third method (graphite furnace atomic absorption spectrometry) for the determination of total arsenic in food in the "GB 5009.11-2024 National Food Safety Standard - Determination of Total Arsenic and Inorganic Arsenic in Food" were selected, and spiked with 30 μg / kg, 100 μg / kg, 210 μg / kg, 320 μg / kg, and 430 μg / kg, respectively. The rice samples were tested using the method in Example 1, and a standard curve was drawn based on the test results. Figure 2 As shown, the standard curve is: y = 94.556x + 10.437, R 2 =0.9996.
[0057] Example 2
[0058] This example provides a method for detecting total arsenic in grain. The method includes three aspects: sample extraction, sample purification, and total arsenic testing in grain. Specifically, the method includes the following steps:
[0059] Step 1: Extraction of total arsenic in grain samples:
[0060] 1g of grain sample was crushed and passed through a 100-mesh sieve, then mixed with the extractant at a liquid-solid ratio of 15mL:1g of extractant to grain sample. After mixing, the mixture was placed in a boiling water bath for 10min.
[0061] The extractant is 10 mL of 1 mol / L hydrochloric acid solution.
[0062] Step 2: Sample purification:
[0063] Add a scavenger to the solution after the boiling water bath in step 1. The scavenger is obtained by mixing 3 mL of 5% zinc acetate solution, 3 mL of 5% potassium ferrocyanide solution, 1 mL of 1% thiourea solution, and 1 mL of 1% sodium citrate solution. Shake well and centrifuge at 8000 r / min for 5 minutes.
[0064] Step 3: Total Arsenic Testing
[0065] Take 4 mL of the supernatant from the centrifugation in step 2, add 0.1 mL of 0.01 mol / L CuCl, 0.2 mL of 1% KCl solution, and 0.2 mL of 0.1 mol / L Hg(NO) and mix vigorously to obtain the test solution. Tests were performed using a portable electrochemical heavy metal detector equipped with screen-printed electrodes.
[0066] The screen-printed electrodes were: a circular carbon working electrode, a square carbon counter electrode, and a square Ag / AgCl reference electrode. The portable electrochemical heavy metal analyzer was configured with the following parameters: an accumulation potential of -0.9 V, an accumulation time of 150 s, a stripping potential of 0 to -1.0 V, two accumulation and stripping cycles, and the final signal was used.
[0067] The test method in this example is used to test the stripping voltammetry curves when the arsenic concentration is 0μg / kg, 50μg / kg, 100μg / kg, 200μg / kg, 500μg / kg, and 1000μg / kg, as shown in the following figure. Figure 3 As shown. Figure 3 It can be seen that the gradient is good within the range of 0 to 1000 μg / kg.
[0068] Example 3
[0069] This example provides a method for detecting total arsenic in grain. The method includes three aspects: sample extraction, sample purification, and total arsenic testing in grain. Specifically, the method includes the following steps:
[0070] Step 1: Extraction of total arsenic in grain samples:
[0071] 1g of grain sample was crushed and passed through a 100-mesh sieve, then mixed with the extractant at a liquid-solid ratio of 20mL:1g of extractant to grain sample. After mixing, the mixture was placed in a boiling water bath for 5min.
[0072] The extractant is 10 mL of 0.5 mol / L sulfuric acid solution.
[0073] Step 2: Sample purification:
[0074] Add a scavenger to the solution after the boiling water bath in step 1. The scavenger is obtained by mixing 3 mL of 5% zinc acetate solution, 3 mL of 5% potassium ferrocyanide solution, 1 mL of 1% thiourea solution, and 1 mL of 0.1% KI solution. Shake well and centrifuge at 8000 r / min for 5 minutes.
[0075] Step 3: Total Arsenic Testing
[0076] Take 4 mL of the supernatant from step 2, add 0.1 mL of 0.5 mol / L CuCl, 0.2 mL of 1% KCl solution, and 0.2 mL of 0.1 mol / L Hg(NO)₂, and mix vigorously to obtain the test solution. Tests were performed using a portable electrochemical heavy metal detector equipped with screen-printed electrodes.
[0077] Screen-printed electrodes were: a circular carbon working electrode, a square carbon counter electrode, and a square Ag / AgCl reference electrode. The portable electrochemical heavy metal analyzer was set with the following parameters: an accumulation potential of -1.1 V, an accumulation time of 240 s, a stripping potential of 0 to -1.0 V, and one accumulation-stripping cycle. The final signal was taken as the final signal.
[0078] Comparative Example 1
[0079] This example provides a method for detecting total arsenic in grains. The method includes sample extraction and total arsenic testing in grains, specifically including the following steps:
[0080] Step 1: Extraction of total arsenic in grain samples:
[0081] 1g of grain sample was crushed and passed through a 100-mesh sieve, then mixed with the extractant at a liquid-solid ratio of 20mL:1g of extractant to grain sample. After mixing, the mixture was placed in a boiling water bath for 5min and centrifuged at 8000r / min in a centrifuge for 5min.
[0082] The extractant is 10 mL of 0.5 mol / L sulfuric acid solution.
[0083] Step 2: Detection of total arsenic:
[0084] Take 4 mL of the supernatant from step 1, add 0.1 mL of 0.5 mol / L CuCl, 0.2 mL of 1% KCl solution, and 0.2 mL of 0.1 mol / L Hg(NO)₂, and mix vigorously to obtain the test solution. Tests were performed using a portable electrochemical heavy metal detector equipped with screen-printed electrodes.
[0085] Screen-printed electrodes were: a circular carbon working electrode, a square carbon counter electrode, and a square Ag / AgCl reference electrode. The portable electrochemical heavy metal analyzer was set with the following parameters: an accumulation potential of -1.1 V, an accumulation time of 240 s, a stripping potential of 0 to -1.0 V, and one accumulation-stripping cycle. The final signal was taken as the final signal.
[0086] The total arsenic content in different grain quality control samples was detected respectively by the detection method in Example 1 and Comparative Example 1. The specific names of the grain quality control samples are: brown rice flour GBW (E) 100378, brown rice flour GBW (E) 100765, brown rice flour GBW (E) 100763, corn flour GBW (E) 100380, corn flour GBW (E) 100377, wheat flour QC1354B-3, and wheat flour 55755C. The values obtained by detecting according to the detection method in Example 1 and Comparative Example 1 are shown in Table 1.
[0087] Table 1 Detection of total arsenic in grain quality control samples
[0088]
[0089]
[0090] As shown in Table 1, the total arsenic content in the grain quality control samples detected by the detection method in Example 1 of the present invention is consistent with the standard value of the quality control samples, and the recovery rate of arsenic in the grain samples is 95-110%, further demonstrating that the detection method of the present invention has high accuracy. The pretreatment steps of the detection method of the present invention only require a boiling water bath and centrifugation, and a single sample pretreatment can be completed in 10-20 minutes. The addition of a purifier and the centrifugation process can remove macromolecules in the grain (such as protein interference). In contrast, the detection method in Comparative Example 1, without the use of a purifier, has a significantly lower test recovery rate of only 16-42%.
[0091] According to the third method of the determination of total arsenic in food, graphite furnace atomic absorption spectrometry, the total arsenic content in the actual rice sample A1 was determined to be 0.34 mg / kg. Then, metal ions were additionally added to the actual rice sample A1, and the total arsenic content in the actual rice sample A1 was tested using the test method in Example 1. The interference of metal ions on arsenic testing was studied by adding additional ions. The metal ions additionally added to the actual rice sample A1 were: 500 mg / kg Mg 2+ , 250mg / kg Ca 2+ 、250mg / kg Fe 3+ , 250mg / kg Al 3+ 、25mg / kg Pb 2+ 、125mg / kg Mn 2+ , 125mg / kg Cu 2+ , 12.5mg / kgHg 2+ 、25mg / kg Cd 2+ 、12.5mg / kgCr 6+, 2.5mg / kg Bi 3+ 、12.5mg / kg Zn 2+ The specific test results are shown in Table 2 below.
[0092] Table 2: Interference of different ions on arsenic testing
[0093]
[0094]
[0095] As can be seen from Table 2, when different types and contents of interfering ions are added to actual grain samples, the test method of the present invention can still accurately measure the total arsenic content in the actual grain samples, and the recovery rate is within the range of 90-105%, and the interference is not obvious, indicating that the test method of the present invention has good anti-interference performance for metal ions.
[0096] The total arsenic content in the rice quality control sample brown rice flour GBW(E)100378 was tested 10 times using the test method in Example 1, and each test result was recorded in Table 3 below.
[0097] Table 3: Repeatability and stability test results
[0098]
[0099] As shown in Table 3, the total arsenic content in the brown rice flour GBW(E)100378 recorded by the test method in the embodiment of the present invention 1 is 196-222 μg / kg, with a recovery of 99-113% and a relative standard deviation of 4.33%, which has excellent repeatability and test stability.
[0100] A sample confirmed as blank using the third method of graphite furnace atomic absorption spectrometry for the determination of total arsenic in food in the "GB5009.11-2024 National Food Safety Standard - Determination of Total Arsenic and Inorganic Arsenic in Food" was selected for testing. The detection limit of the test method of the present invention was estimated to be 36 μg / kg based on the blank standard deviation method. When the test method of the present invention was used to test the actual sample rice flour C4, which had a content of 43 μg / kg according to the national standard method, the test result was detected in 20 tests. Therefore, 43 μg / kg can be used as the actual detection limit of the detection method of the present invention.
[0101] Table 4. Comparison of test time between the present test method and the third method of GB 5009.11-2004
[0102] Detection method GB 5009.11-2024 Part III Example 1 Example 2 Example 3 Comparative Example 1 Detection time of a single sample 120~240 minutes 30min 25min 23min 22min
[0103] The present invention utilizes a portable heavy metal analyzer or electrochemical workstation, and is equipped with the electrochemical detection method of the present invention. It can complete the detection of total arsenic in a single grain sample within 30 minutes. Compared with the detection method in GB 5009.11-2024, the detection time is greatly shortened. The detection method is simple and easy to operate, and has a wide range of applications. It can be applied to the rapid detection of total arsenic in grain samples such as rice, wheat, corn, and soybeans. Compared with traditional detection methods, the detection method in the present invention has a simple, rapid, and low-cost detection process. It can be used to detect total arsenic and has a wider range of applications. In addition, this method does not require the modification of the electrode before each test, which can avoid the tedious process of modifying the electrode and the errors caused by it. It has broad application prospects in the rapid detection and monitoring of heavy metal arsenic in grains.
[0104] While the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.
Claims
1. A method for extracting arsenic from grains, characterized in that: The following steps are involved: The grain and the extractant are mixed and extracted at 95-105° C. to obtain a mixed solution; mixing the mixed liquid with a purifier, and then performing solid-liquid separation to obtain an arsenic-containing extract; The extractant includes an inorganic acid; The purifying agent contains a precipitant and a masking agent; The precipitant includes at least one of zinc acetate, zinc sulfate, potassium ferrocyanide, ammonium sulfate, ammonium acetate, and trichloroacetic acid; the masking agent includes at least one of thiourea, stannous chloride, sodium fluoride, and sodium citrate.
2. The method for extracting arsenic from grain according to claim 1, wherein: The volume mass ratio of the extractant to the grain is (5-20) mL:1 g; And / or, the volume mass ratio of the purifier to the grain is (0.5-10) mL:1 g.
3. The method for extracting arsenic from grain according to claim 1, wherein: The extraction time is 5 to 15 minutes.
4. The method for extracting arsenic from grain according to claim 1, wherein: The volume ratio of the precipitant to the masking agent is (0.5-10):
1.
5. The method for extracting total arsenic from grain according to claim 1, wherein: The inorganic acid includes at least one of HCl, HClO4, HNO3, and H2SO4.
6. A method for detecting total arsenic in grain, characterized in that: The following steps are involved: Extracting arsenic from grains using the method for extracting total arsenic from grains according to any one of claims 1 to 5 to obtain an arsenic-containing extract; Mixing the arsenic-containing extract with a modification solution to obtain a test solution; Cathodic stripping voltammetry was used to detect the test solution using screen-printed electrodes, and the arsenic content in the grain was determined based on the standard curve. The modification solution contains copper salt, mercury salt and potassium salt.
7. The method for detecting total arsenic in grain according to claim 6, wherein: The working electrode and the counter electrode of the screen-printed electrode are both carbon electrodes, and the reference electrode is an Ag / AgCl electrode.
8. The method for detecting total arsenic in grain according to claim 6, wherein: In the modification solution, the concentration of cuprous salt is 0.001-0.5 mol / L, the concentration of mercuric salt is 0.005-0.2 mol / L, and the mass of potassium salt is 0.02-1% of the volume of the modification solution.
9. The method for detecting total arsenic in grain according to claim 6, wherein: The detection has at least one of the following characteristics: (a) The enrichment potential of the detection is -1.1V to -0.8V; (b) The enrichment time of the detection is 120 to 240 seconds; (c) the dissolution potential of the test is 0 to -1.0 V; (d) the number of enrichment and dissolution cycles of the detection is 1-3 times; (e) The detection is performed using an electrochemical workstation or an electrochemical heavy metal detector.
10. The method for detecting total arsenic in grain according to claim 6, wherein: The volume ratio of the modifying liquid to the test liquid is (0.01-0.2):1.