Method for analyzing aldicarb in water

Abstract

The invention discloses a method for analyzing aldicarb in water quality, which comprises the following steps: adding a low-temperature sodium chloride saturated solution into a to-be-analyzed low-temperature preserved water sample, extracting the water sample by using a mixed solvent of acetonitrile and methanol, standing for layering, collecting an organic layer, drying by using anhydrous sodium sulfate, carrying out nitrogen blowing concentration until the organic layer is dry, and fixing the volume by using an acetonitrile formic acid solution; according to the present invention, the detection limit of aldicarb is 0.003 [mu] g / L, the recovery rates of aldicarb with different concentrations are respectively 79.6-93.8%, the determined relative standard deviation is 6.25-11.9%, and the method has advantages of good stability, low detection limit, high recovery rate and the like.

Description

Technical Field

[0001] The invention belongs to the field of analysis and detection, and particularly relates to an analysis method for aldicarb in water. Background Art

[0002] Aldicarb is a carbamate pesticide developed by Union Carbide Corporation in the United States and widely used on crops such as cotton, peanuts, and corn. Upon application, aldicarb is rapidly oxidized to the relatively stable and highly toxic aldicarb sulfoxide, which then oxidizes to the even more stable aldicarb sulfone. Aldicarb is a potent acetylcholinesterase inhibitor that can cause parasympathetic nervous system toxicity, making it one of the most toxic commercial pesticides. Aldicarb is highly water-soluble and difficult to degrade, causing long-term pollution if it enters water bodies.

[0003] The World Health Organization (WHO)'s "Guidelines for Drinking-Water Quality" stipulates a guideline value of 10 μg / L for aldicarb in drinking water, and the U.S. Environmental Protection Agency's "Drinking Water Standards and Health-Based Guidance" stipulates a limit of 3 μg / L for aldicarb in drinking water. my country's "National Drinking Water Quality Standard" (GB 5749-2022) does not specify a limit for aldicarb, and relevant basic data is still lacking. Due to the large annual consumption of aldicarb in my country, its residues in water bodies should also be considered. In order to accurately assess the contamination exposure level of aldicarb in drinking water and source water on a large scale, it is necessary to establish a rapid and applicable trace detection method to further meet my country's increasingly stringent regulatory needs for drinking water and source water.

[0004] At present, the main international detection methods for aldicarb include gas chromatography, liquid chromatography-post-column derivatization, and solid phase extraction-liquid chromatography tandem mass spectrometry. Since aldicarb is thermally unstable, the use of gas chromatography will make the quantification inaccurate due to thermal decomposition, and it needs to be converted into aldicarb sulfone for determination, so only the total amount can be determined. The post-column derivatization method requires a special derivatization device, the operation is relatively complicated, and due to its low specificity, false positives are prone to occur. Liquid chromatography-mass spectrometry has good selectivity and strong anti-interference ability, and its application has been increasing in recent years. Solid phase extraction-liquid chromatography tandem mass spectrometry is used to determine aldicarb, but solid phase extraction has the disadvantages of unstable extraction recovery rate and low recovery rate. The present invention uses salting-out low-temperature liquid-liquid extraction-liquid chromatography tandem mass spectrometry to determine aldicarb, which has the advantages of good method stability, low detection limit, and high recovery rate. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention adopts salting-out low-temperature liquid-liquid extraction-liquid chromatography tandem mass spectrometry to determine aldicarb, which has the advantages of good method stability, low detection limit, high recovery rate, etc., and effectively solves the problems existing in the prior art.

[0006] The analytical method for aldicarb in water quality is as follows: add a low-temperature saturated sodium chloride solution to the water sample to be analyzed and store at low temperature, extract the water sample with a mixed solvent of acetonitrile and methanol, let the extraction stand and separate the layers, collect the organic layer, dry it over anhydrous sodium sulfate, concentrate it to dryness with nitrogen blow, make up to volume with acetonitrile formic acid solution, filter it through a 0.45μm filter membrane, and analyze it with liquid chromatography-mass spectrometry. Qualitative analysis is based on retention time and characteristic ions, and quantitative analysis is based on external standard method.

[0007] Preferably, the volume ratio of acetonitrile to methanol in the mixed extract is 99:1.

[0008] Preferably, the volume ratio of the water sample to the low-temperature saturated sodium chloride solution is 10:1.

[0009] Preferably, the acetonitrile-formic acid solution is a solution in which the volume ratio of acetonitrile to 0.1% formic acid aqueous solution is 1:9.

[0010] The specific pretreatment method is as follows: take 1 L of the water sample to be analyzed and store at low temperature, add 50 mL of low-temperature saturated sodium chloride solution, extract the water sample twice with 30 mL of 1% methanol-acetonitrile solution mixed solvent respectively, let the extraction stand and separate the layers, collect the organic layer, add about 30 g of anhydrous sodium sulfate to dry, concentrate to dryness with nitrogen blow, make the volume to 2.0 mL with 0.1% formic acid-acetonitrile solution, pass through a 0.45 μm filter membrane, and analyze with liquid chromatography-mass spectrometry. Qualitative analysis is based on retention time and characteristic ions, and quantitative analysis is based on external standard method.

[0011] Preferably, the liquid chromatography conditions are as follows: mobile phase: chromatographic column is C18 chromatographic column: 1.7μm 2.1×50mm, reversed phase chromatographic column or other chromatographic columns with similar performance, mobile phase A: acetonitrile, mobile phase B: 0.1% formic acid solution, mobile phase ratio: 80% A + 20% B, flow rate: 0.2ml / min, column temperature: 40°C, injection volume: 10ul; mass spectrometry conditions: EI ion source: positive ion mode; ion source temperature is 120°C; desolvation temperature: 250°C; cone gas flow rate: 50L / h, desolvation gas flow rate: 500L / h, collision gas flow rate: 0.1ml / min, monitoring mode: MRM multiple reaction monitoring, cone voltage CV=30 / 30, collision energy CE=30 / 10, parent ion: 213.0, product ions: 89.0, 116.0, of which quantitative ion: 89.0.

[0012] The beneficial effects achieved by the present invention compared to the prior art are:

[0013] (1) According to the requirements for analytical methods in the Technical Guidelines for the Development of Environmental Monitoring Analytical Method Standards (HJ 168-2020), the concentration of aldicarb meets the requirements of the guidelines within a range of 3 to 5 times the detection limit. Therefore, using laboratory ultrapure water as a 1L blank water sample and adding 20ng of aldicarb to the sample concentration meets the detection limit determination requirements of our laboratory. The detection limit results measured in the table can be used as the final laboratory detection limit. The detection limit of aldicarb is 0.003μg / L.

[0014] (2) Using 1 L of laboratory ultrapure water as a blank sample, 20 ng, 100 ng, 200 ng, and 500 ng of aldicarb were added, mixed, and subjected to liquid-liquid extraction, drying, concentration, constant volume, and analytical determination. The relative standard deviations of the six determinations ranged from 6.25 to 11.9%, indicating good parallelism and precision.

[0015] (3) Using 1 L of ultrapure water as a blank sample, 20 ng, 100 ng, 200 ng, and 500 ng of aldicarb were added, respectively. After mixing, liquid-liquid extraction, drying, concentration, constant volume, and determination were performed. The recoveries of aldicarb were 79.6-93.8%, respectively, meeting the 60-120% requirement for matrix spike in the standard validation method.

[0016] (4) Comparison between the solid phase extraction method and the extraction method of the present invention: Under different pretreatment conditions and using the same instrumental analysis conditions, the comparison of data shows that the recovery rate of the liquid-liquid extraction of the present invention is significantly better than that of the HJ 827-2017 standard method, with good accuracy and precision. DETAILED DESCRIPTION

[0017] Various exemplary embodiments of the present invention are now described in detail. Unless otherwise specified, the methods in the examples are conventional methods. Unless otherwise specified, the reagents used are conventional commercially available reagents or reagents prepared using conventional methods. This detailed description should not be considered a limitation of the present invention, but rather should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0018] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0019] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0020] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0021] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0022] Example 1

[0023] 1. Sample collection and preservation

[0024] Sample collection and storage were carried out in accordance with the relevant provisions of HJ / T 91 and HJ / T 164. After collection, the samples were stored in brown glass bottles. 0.02 g of ascorbic acid was added to remove residual chlorine. The samples were refrigerated and stored below 4°C away from light. The samples were then assayed within 48 hours.

[0025] 2. Sample pretreatment

[0026] Take 1 L of the water sample to be analyzed and store at low temperature, add 50 mL of low-temperature saturated sodium chloride solution, extract the water sample twice with 30 mL of 1% methanol-acetonitrile solution mixed solvent, let the extraction stand and separate the layers, collect the organic layer, add about 30 g of anhydrous sodium sulfate and dry it, concentrate it to dryness with nitrogen blow, make the volume to 2.0 mL with 0.1% formic acid-acetonitrile solution, filter it through a 0.45 μm filter membrane, and analyze it by liquid chromatography-mass spectrometry. Qualitative analysis is based on retention time and characteristic ions, and quantitative analysis is based on external standard method.

[0027] 3. Preparation of blank samples

[0028] Prepare a laboratory blank sample by following the same steps as for the sample preparation, using experimental water instead of the sample.

[0029] 4. On-the-computer analysis

[0030] 4.1 Instrumental analysis conditions

[0031] 4.1.1 Liquid chromatography conditions:

[0032] Mobile phase: Mobile phase A: methanol, Mobile phase B: formic acid solution 1+1000, Mobile phase ratio: 80% A + 20% B. Flow rate: 0.2 ml / min, Column temperature: 40°C, Injection volume: 10 μl.

[0033] 4.1.2 Mass spectrometry conditions:

[0034] Ion source: Electrospray ionization (ESI) in positive ion mode; Ion source (EI) temperature: 120°C; Desolvation gas temperature: 250°C; Cone gas flow rate: 50 L / h, Desolvation gas flow rate: 500 L / h, Collision gas flow rate: 0.1 ml / min. Monitoring: Multiple Reaction Monitoring (MRM), Cone voltage CV = 30 / 30, Collision energy CE = 30 / 10, Parent ion: 213.0, Product ions: 89.0 and 116.0, Quantitation ion: 89.0.

[0035] 5. Establishment of calibration curve

[0036] Prepare a standard series of at least five concentration points using a certain amount of aldicarb standard working solution. Take 1.0 mL of each prepared standard solution, mix thoroughly, and store in a brown sample bottle until ready for testing. Inject the standard series solutions sequentially from low to high concentrations. Construct a standard curve using the concentration of the target component in the standard series solutions as the horizontal axis and the corresponding peak area as the vertical axis.

[0037] 6. Determination of sample and blank

[0038] To a 1.L blank sample of laboratory ultrapure water, 20 ng of aldicarb was added. The mixture was mixed and subjected to the above pretreatment. Seven spiked samples were analyzed according to the above pretreatment and analytical methods. The detection limit and lower determination limit of the method were calculated with reference to the Technical Guidelines for the Development of Environmental Monitoring Analytical Method Standards (HJ 168-2020).

[0039] Table 1 Method detection limit and determination lower limit test data table

[0040]

[0041] According to the analytical method requirements in the "Technical Guidelines for the Development of Environmental Monitoring Analytical Method Standards" (HJ 168-2020), the aldicarb concentrations listed in Table 4 meet the requirements of the guidelines within a range of 3 to 5 times the detection limit. Therefore, using laboratory ultrapure water as a 1L blank sample and adding 20ng of aldicarb to the sample concentration meets the detection limit requirements of our laboratory. The detection limit results in the table can be used as the final laboratory detection limit, which is 0.003μg / L for aldicarb.

[0042] Example 2

[0043] 1. Sample collection and preservation

[0044] Sample collection and storage were carried out in accordance with the relevant provisions of HJ / T 91 and HJ / T 164. After collection, the samples were stored in brown glass bottles. 0.02 g of ascorbic acid was added to remove residual chlorine. The samples were refrigerated and stored below 4°C away from light. The samples were then assayed within 48 hours.

[0045] 2. Sample pretreatment

[0046] Take 1 L of the water sample to be analyzed and store at low temperature, add 50 mL of low-temperature saturated sodium chloride solution, extract the water sample twice with 30 mL of 1% methanol-acetonitrile solution mixed solvent, let the extraction stand and separate the layers, collect the organic layer, add about 30 g of anhydrous sodium sulfate and dry it, concentrate it to dryness with nitrogen blow, make the volume to 2.0 mL with 0.1% formic acid-acetonitrile solution, filter it through a 0.45 μm filter membrane, and analyze it by liquid chromatography-mass spectrometry. Qualitative analysis is based on retention time and characteristic ions, and quantitative analysis is based on external standard method.

[0047] 3. Preparation of blank samples

[0048] Prepare a laboratory blank sample by following the same steps as for the sample preparation, using experimental water instead of the sample.

[0049] 4. On-the-computer analysis

[0050] 4.1 Instrumental analysis conditions

[0051] 4.1.1 Liquid chromatography conditions:

[0052] Mobile phase: Mobile phase A: methanol, Mobile phase B: formic acid solution 1+1000, Mobile phase ratio: 80% A + 20% B. Flow rate: 0.2 ml / min, Column temperature: 40°C, Injection volume: 10 μl.

[0053] 4.1.2 Mass spectrometry conditions:

[0054] Ion source: Electrospray ionization (ESI) in positive ion mode; Ion source (EI) temperature: 120°C; Desolvation gas temperature: 250°C; Cone gas flow rate: 50 L / h, Desolvation gas flow rate: 500 L / h, Collision gas flow rate: 0.1 ml / min. Monitoring: Multiple Reaction Monitoring (MRM), Cone voltage CV = 30 / 30, Collision energy CE = 30 / 10, Parent ion: 213.0, Product ions: 89.0 and 116.0, Quantitation ion: 89.0.

[0055] 5. Establishment of calibration curve

[0056] Prepare a standard series of at least five concentration points using a certain amount of aldicarb standard working solution. Take 1.0 mL of each prepared standard solution, mix thoroughly, and store in a brown sample bottle until ready for testing. Inject the standard series solutions sequentially from low to high concentrations. Construct a standard curve using the concentration of the target component in the standard series solutions as the horizontal axis and the corresponding peak area as the vertical axis.

[0057] 6. Determination of sample and blank

[0058] Using 1.0 L of laboratory ultrapure water as a blank sample, 20 ng, 100 ng, 200 ng, and 500 ng of aldicarb were added, respectively. Six spiked samples were analyzed according to the above pretreatment and analytical methods, and the RSD was calculated. The method precision data was calculated according to the "Technical Guidelines for the Development of Environmental Monitoring Analytical Method Standards" (HJ 168-2020).

[0059] Table 2 Precision test data

[0060]

[0061]

[0062] Using 1 L of laboratory ultrapure water as a blank sample, 20 ng, 100 ng, 200 ng, and 500 ng of aldicarb were added, mixed, and subjected to liquid-liquid extraction, drying, concentration, constant volume, and analysis. The relative standard deviations of the six determinations ranged from 6.25 to 11.9%, demonstrating good parallelism and precision.

[0063] Example 3

[0064] 1. Sample collection and preservation

[0065] Sample collection and storage were carried out in accordance with the relevant provisions of HJ / T 91 and HJ / T 164. After collection, the samples were stored in brown glass bottles. 0.02 g of ascorbic acid was added to remove residual chlorine. The samples were refrigerated and stored below 4°C away from light. The samples were then assayed within 48 hours.

[0066] 2. Sample pretreatment

[0067] Take 1 L of the water sample to be analyzed and store at low temperature, add 50 mL of low-temperature saturated sodium chloride solution, extract the water sample twice with 30 mL of 1% methanol-acetonitrile solution mixed solvent, let the extraction stand and separate the layers, collect the organic layer, add about 30 g of anhydrous sodium sulfate and dry it, concentrate it to dryness with nitrogen blow, make the volume to 2.0 mL with 0.1% formic acid-acetonitrile solution, filter it through a 0.45 μm filter membrane, and analyze it by liquid chromatography-mass spectrometry. Qualitative analysis is based on retention time and characteristic ions, and quantitative analysis is based on external standard method.

[0068] 3. Preparation of blank samples

[0069] Prepare a laboratory blank sample by following the same steps as for the sample preparation, using experimental water instead of the sample.

[0070] 4. On-the-computer analysis

[0071] 4.1 Instrumental analysis conditions

[0072] 4.1.1 Liquid chromatography conditions:

[0073] Mobile phase: Mobile phase A: methanol, Mobile phase B: formic acid solution 1+1000, Mobile phase ratio: 80% A + 20% B. Flow rate: 0.2 ml / min, Column temperature: 40°C, Injection volume: 10 μl.

[0074] 4.1.2 Mass spectrometry conditions:

[0075] Ion source: Electrospray ionization (ESI) in positive ion mode; Ion source (EI) temperature: 120°C; Desolvation gas temperature: 250°C; Cone gas flow rate: 50 L / h, Desolvation gas flow rate: 500 L / h, Collision gas flow rate: 0.1 ml / min. Monitoring: Multiple Reaction Monitoring (MRM), Cone voltage CV = 30 / 30, Collision energy CE = 30 / 10, Parent ion: 213.0, Product ions: 89.0 and 116.0, Quantitation ion: 89.0.

[0076] 5. Establishment of calibration curve

[0077] Prepare a standard series of at least five concentration points using a certain amount of aldicarb standard working solution. Take 1.0 mL of each prepared standard solution, mix thoroughly, and store in a brown sample bottle until ready for testing. Inject the standard series solutions sequentially from low to high concentrations. Construct a standard curve using the concentration of the target component in the standard series solutions as the horizontal axis and the corresponding peak area as the vertical axis.

[0078] 6. Determination of sample and blank

[0079] Using 1 L of laboratory ultrapure water as a blank sample, 20 ng, 100 ng, 200 ng, and 500 ng of aldicarb were added, respectively. Following the above sample preparation method, six parallel measurements were performed, and the recovery rate was calculated. The method accuracy data was calculated according to the Technical Guidelines for the Development of Environmental Monitoring Analytical Method Standards (HJ 168-2020).

[0080] Table 3 Blank spike test data

[0081]

[0082] Using 1L of laboratory ultra-pure water as a blank sample, 20ng, 100ng, 200ng and 500ng of aldicarb were added, respectively. After mixing, liquid-liquid extraction, drying, concentration, constant volume and determination were performed. The recoveries of aldicarb were 79.6-93.8%, respectively, meeting the 60-120% requirement for matrix spike in the standard validation method.

[0083] Example 4

[0084] Comparison between solid phase extraction and the extraction method of the present invention:

[0085] 1. The solid phase extraction method adopts the extraction method of HJ 827-2017. The specific operation steps are as follows:

[0086] 1.1 Preparation of samples

[0087] 1.1.1 Activation: Activate the solid phase extraction column with 6 mL of acetonitrile and 6 mL of high-purity water at a flow rate of 2 mL / min.

[0088] 1.1.2 Enrichment: Take 1L of water sample and enrich it at a flow rate of 10mL / min. The volume of water used for enrichment can be appropriately increased or decreased based on the actual situation of the water sample. Water samples with high suspended matter content need to be filtered through a filtration device before solid phase extraction pretreatment.

[0089] 1.1.3 Eluent: Elute the solid phase extraction column with 5 mL of high-purity water at a flow rate of 10 mL / min. After elution, blow dry with nitrogen.

[0090] 1.1.4 Elution: Elute the aldicarb adsorbed on the solid phase extraction column with 2 mL of acetonitrile at a flow rate of 2 mL / min. Collect the eluate. If any water remains in the eluate, add anhydrous sodium sulfate to dry it.

[0091] 1.1.5 Make up the volume: blow out the eluted liquid nitrogen and accurately make up the volume to 1.0 mL with acetonitrile for testing.

[0092] 1.1.6 Preparation of blank sample: Replace the sample with experimental water and prepare the laboratory blank sample according to the same steps as the sample preparation.

[0093] 1.2. The instrument conditions are the same as those of the liquid-liquid extraction method.

[0094] 1.2.1 Liquid chromatography conditions:

[0095] Mobile phase: Mobile phase A: methanol, Mobile phase B: formic acid solution 1+1000, Mobile phase ratio: 80% A + 20% B. Flow rate: 0.2 ml / min, Column temperature: 40°C, Injection volume: 10 μl.

[0096] 1.2.2 Mass spectrometry conditions:

[0097] Ion source: Electrospray ionization (ESI) in positive ion mode; Ion source (EI) temperature: 120°C; Desolvation gas temperature: 250°C; Cone gas flow rate: 50 L / h, Desolvation gas flow rate: 500 L / h, Collision gas flow rate: 0.1 ml / min. Monitoring: Multiple Reaction Monitoring (MRM), Cone voltage CV = 30 / 30, Collision energy CE = 30 / 10, Parent ion: 213.0, Product ions: 89.0 and 116.0, Quantitation ion: 89.0.

[0098] 2. The instrumental analysis conditions are the same as those of the solid phase extraction method. The specific operating steps of the liquid-liquid extraction method of the present invention are as follows:

[0099] 2.1 Sample pretreatment

[0100] Take 1 L of the water sample to be analyzed and store at low temperature, add 50 mL of low-temperature saturated sodium chloride solution, extract the water sample twice with 30 mL of 1% methanol-acetonitrile solution mixed solvent, let the extraction stand and separate the layers, collect the organic layer, add about 30 g of anhydrous sodium sulfate and dry it, concentrate it to dryness with nitrogen blow, make the volume to 2.0 mL with 0.1% formic acid-acetonitrile solution, filter it through a 0.45 μm filter membrane, and analyze it by liquid chromatography-mass spectrometry. Qualitative analysis is based on retention time and characteristic ions, and quantitative analysis is based on external standard method.

[0101] 3. Preparation of blank sample spike

[0102] Prepare laboratory blank samples using the same steps as for sample preparation, replacing the sample with experimental water. Using 1 L of laboratory ultrapure water as the blank sample, add 20 ng, 100 ng, 200 ng, and 500 ng of aldicarb, respectively. Perform six replicates using the two sample preparation methods described above. Calculate the recovery rate. Accuracy data was calculated according to the "Technical Guidelines for the Development of Environmental Monitoring Analytical Method Standards" (HJ 168-2020).

[0103] Table 4 Comparative data of different pretreatment methods

[0104]

[0105] From the above data, it can be seen that the recovery rate of the liquid-liquid extraction of the present invention is significantly higher than that of the HJ 827-2017 standard method, has good accuracy and precision, and fully meets the current analysis method of aldicarb in water quality.

Claims

1. A method for analyzing aldicarb in water, characterized by: A saturated solution of low-temperature sodium chloride was added to the water sample to be analyzed and stored at low temperature. The water sample was extracted with a mixed solvent of acetonitrile and methanol. After the extraction was allowed to stand and separate, the organic layer was collected, dried over anhydrous sodium sulfate, concentrated to dryness with nitrogen blown, and the volume was made up with acetonitrile formic acid solution. The sample was filtered through a 0.45 μm filter membrane and analyzed by liquid chromatography-mass spectrometry. The qualitative analysis was based on the retention time and characteristic ions, and the quantitative analysis was based on the external standard method.

2. The method for analyzing aldicarb in water according to claim 1, wherein: The volume ratio of acetonitrile to methanol in the mixed extract was 99:

1.

3. The method for analyzing aldicarb in water according to claim 1, wherein: The volume ratio of water sample to low-temperature sodium chloride saturated solution is 10:

1.

4. The method for analyzing aldicarb in water according to claim 1, wherein: The acetonitrile-formic acid solution is a mixture of acetonitrile and 0.1% formic acid aqueous solution in a volume ratio of 1:

9.

5. The method for analyzing aldicarb in water according to claim 1, wherein: The specific pretreatment method is as follows: take 1 L of the water sample to be analyzed and store at low temperature, add 50 mL of low-temperature saturated sodium chloride solution, extract the water sample twice with 30 mL of 1% methanol-acetonitrile solution mixed solvent respectively, let the extraction stand and separate the layers, collect the organic layer, add about 30 g of anhydrous sodium sulfate to dry, concentrate to dryness with nitrogen blow, make the volume to 2.0 mL with 0.1% formic acid-acetonitrile solution, pass through a 0.45 μm filter membrane, and analyze with liquid chromatography-mass spectrometry. Qualitative analysis is based on retention time and characteristic ions, and quantitative analysis is based on external standard method.

6. A method for analyzing aldicarb in water according to claims 1 to 5, characterized in that: Liquid chromatography conditions were as follows: mobile phase: mobile phase A acetonitrile, mobile phase B formic acid solution 1+1000, isocratic elution: 80% A+20% B, flow rate: 0.2 ml / min, column temperature: 40°C, injection volume: 10 ul; mass spectrometry conditions: EI ion source: positive ion mode; ion source temperature was 120°C; desolvation temperature: 250°C; cone gas flow rate: 50 L / h, desolvation gas flow rate: 500 L / h, collision gas flow rate: 0.1 ml / min, monitoring mode: MRM multiple reaction monitoring, cone voltage CV=30 / 30, collision energy CE=30 / 10, parent ion: 213.0, daughter ions: 89.0, 116.0, of which quantitative ion: 89.0.

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