Liquid chromatography-triple quadrupole mass spectrometry detection method for amide compounds in soil and sediments

Abstract

The invention discloses a liquid chromatography-triple quadrupole mass spectrometry detection method for three amide compounds in soil and sediments, which comprises the following steps: carrying out methanol ultrasonic extraction, purification and concentration on the amide compounds in the soil and sediments, separating in a liquid chromatograph, and detecting by a triple quadrupole mass spectrometry detector. The method for determining the three amide compounds in the soil and the sediment has lower detection limit and higher recovery rate, the method verification detection limits of acrylamide, N, N-dimethylformamide and N, N-dimethylacetamide are respectively 10ug / kg, 9ug / kg and 11ug / kg (the sampling amount is 2g), the adding standard recovery rate of a soil matrix sample is 91.1%-94.9%, the adding standard recovery rate of a sediment sample is 88.0%-91.0%, and the content of the amide compounds in the soil and the sediment is greatly reduced. And the technical requirements of soil pollution condition investigation, risk assessment and remediation effect evaluation detection are met.

Description

Technical Field

[0001] The present invention relates to the technical field of amide compound detection, and in particular to a liquid chromatography-triple quadrupole mass spectrometry detection method for three amide compounds, namely acrylamide, N,N-dimethylformamide and N,N-dimethylacetamide, in soil and sediment. Background Art

[0002] Acrylamide is a water-soluble small molecule organic substance used in the paper, wood and textile industries, and its polymers are widely used as soil conditioners. Polyacrylamide itself is non-toxic, but it will produce toxic substances after degradation in the soil, and will be absorbed by the human body directly or through groundwater through the skin, mouth, etc., causing neurotoxicity, movement disorders, etc.; N,N-dimethylformamide and N,N-dimethylacetamide are a class of widely used chemical raw materials and good industrial organic solvents. As raw materials or intermediates, they are widely used in acrylic spinning, petrochemicals, electronics, organic dyes, pharmaceutical chemicals and other industries. N,N-dimethylformamide and N,N-dimethylacetamide can enter the body through breathing, skin contact, etc., which can cause respiratory and digestive tract irritation, leading to nausea, vomiting and diarrhea, and have moderate irritation to the eyes and skin. Long-term contact can lead to dysfunction of the central nervous system, damage important organs such as the liver, kidneys, and stomach, and have carcinogenic effects. N,N-dimethylformamide and N,N-dimethylacetamide may leak during production, transportation, storage and use, thus causing soil pollution. Most amide compounds are toxic, persistent, mobile and bioaccumulative, which have adverse effects on the environment and public health. Amide compound pollution has become an environmental problem that cannot be ignored. How to accurately identify the types and contents of amide compounds in the soil environment is an urgent problem that needs to be solved.

[0003] At present, there are many related research reports on the determination of acrylamide in water using liquid chromatography-mass spectrometry, high performance liquid chromatography, and gas chromatography, and the determination of N,N-dimethylformamide and N,N-dimethylacetamide in air and exhaust gas using gas chromatography. There are few studies on the detection of acrylamide, N,N-dimethylformamide, and N,N-dimethylacetamide in soil. At present, the country has not yet issued a standard detection method for acrylamide, N,N-dimethylformamide, and N,N-dimethylacetamide in soil. Therefore, it is urgent to develop a detection technology that is simple to operate, highly sensitive, and reproducible, and can simultaneously qualitatively identify and quantitatively analyze multiple amide compounds in soil / sediment. Summary of the invention

[0004] The purpose of the present invention is to provide a method for determining amide compounds which is convenient for soil and sediment sample extraction operation, has strong qualitative anti-interference ability and high quantitative accuracy. Methanol is used to ultrasonically extract acrylamide, N,N-dimethylformamide and N,N-dimethylacetamide in soil and sediment. The extract is concentrated and purified, then enters a liquid chromatograph for separation and is detected by a triple quadrupole mass spectrometer, so as to solve the technical defects of existing detection methods in qualitative analysis, sample extraction and other aspects.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] Provided is a liquid chromatography-triple quadrupole mass spectrometry method for detecting three amide compounds, acrylamide, N,N-dimethylformamide and N,N-dimethylacetamide, in soil and sediment, which specifically comprises the following steps:

[0007] Step 1. Sample collection and storage: Soil samples are collected according to the "Technical Specifications for Soil Environmental Monitoring" (HJ / T 166), and sediment samples are collected according to the "Ocean Monitoring Specifications" (GB17378.3), and stored in clean brown glass bottles; samples should be refrigerated, light-proof, and sealed during transportation. If they cannot be analyzed and measured in time, they should be refrigerated below 4°C and light-proof;

[0008] Step 2, sample preparation: put the sample on a porcelain plate or stainless steel plate, mix it, and remove foreign matter such as branches, leaves, and stones; fresh soil or sediment samples are freeze-dried and placed in a vacuum freeze dryer for dehydration; after drying, the sample needs to be ground, sieved, and homogenized into particles for use;

[0009] Step 3, extraction, purification and concentration of samples: weigh (2.00±0.01) g of freeze-dried soil sample, place in a 50 mL polyethylene centrifuge tube, add 2-10 mL (more preferably 3-7 mL) of methanol, seal and mix with a vortex mixer; after ultrasonic extraction for 10-60 minutes (more preferably 20-40 minutes), centrifuge at 6000 rpm for 10 minutes, take 1 mL of sample and filter into a sample injection vial for testing;

[0010] Step 4, liquid chromatography-triple quadrupole mass spectrometer conditions:

[0011] The liquid phase conditions are as follows: the mobile phase (A) is 0% to 0.02% formic acid water (further optimized to 0% to 0.01%), the mobile phase (B) is methanol, wherein the mobile phase (A): mobile phase (B) = 1:3 to 2:1 (further preferably 1:3 to 1:1); flow rate: 0.1 to 0.8 mL / min (further preferably 0.2 to 0.5 mL / min); injection volume: 5.0 μL; column temperature: 10 to 70° C. (further preferably 20 to 60° C.);

[0012] The triple quadrupole mass spectrometry conditions are as follows: ion source: ESI+; nebulizer gas flow rate: 1-8 L / min (more preferably 2-5 L / min); drying gas flow rate: 10 L / min; DL temperature: 270°C; interface temperature: 250-350°C (more preferably 280-320°C); detection method: multiple reaction monitoring;

[0013] Step 5, standard curve establishment: pipette amide mixed standard solutions with concentrations of 0 μg / L, 10 μg / L, 20 μg / L, 50 μg / L, 100 μg / L, and 200 μg / L, respectively, and analyze them in sequence from low concentration to high concentration according to the instrument conditions in step 4, record the chromatographic peak area, and plot the three amide compounds in the linear range with the peak area of ​​the chromatographic peak as the ordinate and the target concentration as the abscissa to draw a standard working curve;

[0014] Step 6, sample determination: set the liquid chromatography-triple quadrupole mass spectrometer conditions according to step 4, and after the conditions are stable, send the extracted concentrate after volume adjustment in step 3 into the liquid chromatograph through an automatic sampler for separation and detection by a mass spectrometer detector, and perform qualitative analysis based on retention time and characteristic ions and quantitative analysis based on external standard method;

[0015] Step 7, result calculation: According to the peak area of ​​amide compounds measured by liquid chromatography-triple quadrupole mass spectrometry, the concentration of amide compounds in the extract is calculated using the standard curve equation, and then the concentration of the amide compounds to be tested in the soil / sediment sample is calculated based on the sample sampling amount.

[0016] The mass concentration of the target substance in the soil sample W 1i :

[0017]

[0018] Where: W 1i ——Concentration of target substance i in soil sample, μg / kg;

[0019] P 1i ——Concentration of the i-th target substance in the soil sample, μg / L;

[0020] V1——the constant volume of the sample, mL;

[0021] M1——mass of soil sample, g;

[0022] W dm ——Soil dry matter content, %

[0023] Mass concentration of target substance in sediment W 2i :

[0024]

[0025] Where: W 2i ——Concentration of the i-th target substance in the sediment sample, μg / kg;

[0026] P 2i ——Concentration of the i-th target substance in the sediment sample, μg / L;

[0027] V2——fixed volume of the sample, mL;

[0028] M2——mass of sediment sample, g;

[0029] W H2O ——Sediment moisture content, %

[0030] Most preferably, a liquid chromatography-triple quadrupole mass spectrometry method for detecting three amide compounds, acrylamide, N,N-dimethylformamide and N,N-dimethylacetamide, in soil and sediments specifically comprises the following steps:

[0031] Step 1. Sample collection and storage: Soil samples are collected according to the "Technical Specifications for Soil Environmental Monitoring" (HJ / T 166), and sediment samples are collected according to the "Ocean Monitoring Specifications" (GB17378.3), and stored in clean brown glass bottles; samples should be refrigerated, light-proof, and sealed during transportation. If they cannot be analyzed and measured in time, they should be refrigerated below 4°C and light-proof;

[0032] Step 2, sample preparation: put the sample on a porcelain plate or stainless steel plate, mix it, and remove foreign matter such as branches, leaves, and stones; fresh soil or sediment samples are freeze-dried and placed in a vacuum freeze dryer for dehydration; after drying, the sample needs to be ground, sieved, and homogenized into particles for use;

[0033] Step 3, sample extraction, purification and concentration: Weigh (2.00±0.01) g of freeze-dried soil sample, place in a 50 mL polyethylene centrifuge tube, add 5 mL of methanol, seal and mix with a vortex mixer; after ultrasonic extraction for 30 minutes, centrifuge at 6000 rpm for 10 minutes, take 1 mL of sample and filter into a sample vial for testing;

[0034] Step 4, liquid chromatography-triple quadrupole mass spectrometer conditions:

[0035] The liquid phase conditions were as follows: mobile phase (A) was 0.005% formic acid water, mobile phase (B) was methanol, wherein mobile phase (A): mobile phase (B) = 2:3; flow rate: 0.3 mL / min; injection volume: 5.0 μL; column temperature: 40°C;

[0036] The triple quadrupole mass spectrometry conditions were as follows: ion source: ESI+; nebulizer gas flow rate: 3 L / min; drying gas flow rate: 10 L / min; DL temperature: 270°C; interface temperature: 300°C; detection method: multiple reaction monitoring;

[0037] Step 5, standard curve establishment: pipette amide mixed standard solutions with concentrations of 0 μg / L, 10 μg / L, 20 μg / L, 50 μg / L, 100 μg / L, and 200 μg / L, respectively, and analyze them in sequence from low concentration to high concentration according to the instrument conditions in step 4, record the chromatographic peak area, and plot the three amide compounds in the linear range with the peak area of ​​the chromatographic peak as the ordinate and the target concentration as the abscissa to draw a standard working curve;

[0038] Step 6, sample determination: set the liquid chromatography-triple quadrupole mass spectrometer conditions according to step 4, and after the conditions are stable, send the extracted concentrate after volume adjustment in step 3 into the liquid chromatograph through an automatic sampler for separation and detection by a mass spectrometer detector, and perform qualitative analysis based on retention time and characteristic ions and quantitative analysis based on external standard method;

[0039] Step 7, result calculation: According to the peak area of ​​amide compounds measured by liquid chromatography-triple quadrupole mass spectrometry, the concentration of amide compounds in the extract is calculated using the standard curve equation, and then the concentration of the amide compounds to be tested in the soil / sediment sample is calculated based on the sample sampling amount.

[0040] The mass concentration of the target substance in the soil sample W 1i :

[0041]

[0042] Where: W 1i ——Concentration of target substance i in soil sample, μg / kg;

[0043] P 1i ——Concentration of the i-th target substance in the soil sample, μg / L;

[0044] V1——the constant volume of the sample, mL;

[0045] M1——mass of soil sample, g;

[0046] W dm ——Soil dry matter content, %

[0047] Mass concentration of target substance in sediment W 2i :

[0048]

[0049] Where: W 2i——Concentration of the i-th target substance in the sediment sample, μg / kg;

[0050] P 2i ——Concentration of the i-th target substance in the sediment sample, μg / L;

[0051] V2——fixed volume of the sample, mL;

[0052] M2——mass of sediment sample, g;

[0053] W H2O ——Sediment moisture content, %

[0054] The present invention adopts the above technical solution, and has the following technical effects compared with the prior art:

[0055] 1. The use of liquid chromatography-triple quadrupole mass spectrometry detector for qualitative and quantitative analysis is a new qualitative technical route different from the existing literature methods. Compared with the methods described in the literature, the instrument used in the present invention has lower maintenance costs and is easier to popularize; the detection method has higher resolution and strong anti-interference ability.

[0056] 2. The method of the present invention determines three amide compounds in soil and sediment with a low detection limit and a high recovery rate. The method validation detection limits of acrylamide, N,N-dimethylformamide and N,N-dimethylacetamide are 10ug / kg, 9ug / kg and 11ug / kg (sampling volume is 2g), respectively. The recovery rate of soil matrix samples with spike addition is 91.1% to 94.9%, and the recovery rate of sediment samples with spike addition is 88.0% to 91.0%, which meets the detection technology requirements for soil pollution status investigation, risk assessment and remediation effect evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 The standard curves of three amide compounds are as follows: (a) acrylamide; (b) N,N-dimethylacetamide; (c) N,N-dimethylformamide. DETAILED DESCRIPTION

[0058] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but is not intended to be limiting of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention may be combined with each other without conflict.

[0059] Instruments and reagents used in the examples:

[0060] Liquid chromatography-triple quadrupole mass spectrometer, model Shimadzu LCMS-8045, with Shimadzu Shim-pack GIST-HPC18 chromatographic column (3 μm×2.mm×100 mm), Shimadzu Corporation.

[0061] Vacuum freeze dryer, model SCIENTZ18N, Ningbo Xinzhi Biotechnology Co., Ltd.

[0062] Vortex mixer, model, Vortex, Shanghai Huxi Industrial Co., Ltd.

[0063] Ultrasonic cleaning machine, model SA14A, Jianer Ultrasonic Appliance Co., Ltd.

[0064] Electronic balance, model YP502N, Shanghai Tianmei Balance Instrument Co., Ltd.

[0065] Amide mixed standard solution, 100 mg / L, Tanmo Quality Inspection Technology Co., Ltd.

[0066] Methanol and formic acid, chromatographic grade, were purchased from Shanghai Anpu Laboratory Technology Co., Ltd.

[0067] The detection method steps of the present invention are:

[0068] (1) Sample collection and storage: Soil samples were collected in accordance with the Technical Specifications for Soil Environmental Monitoring (HJ / T 166), and sediment samples were collected in accordance with the Specifications for Marine Monitoring (GB17378.3). They were stored in clean brown glass bottles. Samples should be refrigerated, protected from light, and sealed during transportation. If they cannot be analyzed and measured in time, they should be refrigerated at below 4°C and protected from light.

[0069] (2) Sample preparation: Place the sample on a porcelain plate or stainless steel plate, mix well, and remove foreign matter such as branches, leaves, and stones. Fresh soil or sediment samples are freeze-dried and placed in a vacuum freeze dryer for dehydration. After drying, the sample needs to be ground, sieved, and homogenized into particles for later use.

[0070] (3) Sample extraction, purification and concentration: Weigh (2.00±0.01) g of freeze-dried soil sample and place it in a 50 mL polyethylene centrifuge tube. Add 5 mL of methanol, seal and mix well with a vortex mixer. After ultrasonic extraction for 30 minutes, centrifuge at 6000 rpm for 10 minutes, take 1 mL of sample and filter into a sample vial for testing.

[0071] (4) Liquid chromatography-triple quadrupole mass spectrometer conditions: Liquid phase conditions are as follows: mobile phase (A) is 0.005% formic acid water, mobile phase (B) is methanol, wherein mobile phase (A): mobile phase (B) = 2:3; flow rate: 0.3 mL / min; injection volume: 5.0 μL; column temperature: 40°C. Triple quadrupole mass spectrometer conditions are as follows: ion source: ESI+; nebulizer gas flow rate: 3 L / min; drying gas flow rate: 10 L / min; DL temperature: 270°C; interface temperature: 300°C; detection method: multiple reaction monitoring.

[0072] (5) Preparation of amide mixed standard working solution I: Accurately measure 1 mL of amide mixed standard solution into a 10 mL volumetric flask and dilute to 10 mL with methanol as the standard working solution with a concentration of 10 mg / L.

[0073] (6) Preparation of amide mixed standard working solution II: Accurately measure 1 mL of amide mixed standard working solution I into a 10 mL volumetric flask and dilute to 10 mL with methanol as the standard working solution with a concentration of 1 mg / L.

[0074] (7) Establishing a standard curve: pipette amide mixed standard solutions with concentrations of 0 μg / L, 10 μg / L, 20 μg / L, 50 μg / L, 100 μg / L, and 200 μg / L, respectively, and analyze them in sequence from low concentration to high concentration according to the instrument conditions in (4), record the chromatographic peak area, and draw a standard working curve with the peak area of ​​the chromatographic peak as the ordinate and the target substance concentration as the abscissa. Figure 1 The standard curves of three amide compounds are shown in Figure 1, where the standard curve of acrylamide is y=6718.9x+27961.0, and the linear correlation coefficient (R 2 ) is 0.999; the standard curve of N,N-dimethylacetamide is y=40088.8x+49801.6, and the linear correlation coefficient (R 2 ) is 0.999; the standard curve of N,N-dimethylformamide is y=7456.7x+30370.4, and the linear correlation coefficient (R 2 ) is 0.999.

[0075] (8) Sample determination: Set the liquid chromatography-triple quadrupole mass spectrometer conditions according to (4). After the conditions are stable, the extract concentrate after volume adjustment in step 3 is sent to the liquid chromatograph through an automatic sampler for separation and detection by a mass spectrometer. The sample is qualitatively determined based on the retention time and characteristic ions and quantitatively determined based on the external standard method.

[0076] (9) Result calculation: Based on the peak area of ​​amide compounds measured by liquid chromatography-triple quadrupole mass spectrometry, the concentration of amide compounds in the extract is calculated using the standard curve equation, and then the concentration of the amide compounds to be tested in the soil / sediment sample is calculated based on the sample sampling amount.

[0077] The mass concentration of the target substance in the soil sample W 1i :

[0078]

[0079] Where: W 1i ——Concentration of target substance i in soil sample, μg / kg;

[0080] P 1i——Concentration of the i-th target substance in the soil sample, μg / L;

[0081] V1——the constant volume of the sample, mL;

[0082] M1——mass of soil sample, g;

[0083] W dm ——Soil dry matter content, %

[0084] Mass concentration of target substance in sediment W 2i :

[0085]

[0086] Where: W 2i ——Concentration of the i-th target substance in the sediment sample, μg / kg;

[0087] P 2i ——Concentration of the i-th target substance in the sediment sample, μg / L;

[0088] V2——fixed volume of the sample, mL;

[0089] M2——mass of sediment sample, g;

[0090] W H2O ——Sediment moisture content, %

[0091] Example 1

[0092] Method precision: Place the field-adjusted columnar soil sample of a chemical enterprise on a porcelain plate or stainless steel plate, mix well, remove foreign matter such as branches, leaves, and stones, and grind, sieve, and homogenize the sample after drying. Weigh 2g of sample, accurately pipette amide mixed standard solution I (10mg / L) into the extraction pool of the soil matrix sample with a micropipette, extract and concentrate, and adjust the volume to 1mL. According to the instrument conditions in step 4, the sample is sent to the liquid chromatograph by the automatic sampler for separation and detected by the triple quadrupole mass spectrometer to determine the content of amide compounds in the soil matrix sample. Repeat the above operation 6 times for precision determination. The precision determination data are shown in Table 1.

[0093] Table 1

[0094]

[0095] Example 2

[0096] Method accuracy: Place the groundwater sediment sample of a domestic waste landfill on a porcelain plate or stainless steel plate, mix well, remove foreign matter such as branches, leaves, and stones, and grind, sieve, and homogenize the sample after drying. Weigh 2g of the sample, accurately pipette the amide mixed standard solution I (10mg / L) into the extraction pool of the soil matrix sample with a micropipette, extract and concentrate it to 1mL, and send it to the liquid chromatograph through the automatic sampler for separation according to the instrument conditions in step 4 and detect it by a triple quadrupole mass spectrometer to determine the content of amide compounds in the sediment matrix sample. The accuracy determination data is shown in Table 2.

[0097] Table 2

[0098]

[0099]

[0100] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A liquid chromatography-triple quadrupole mass spectrometry method for detecting three amide compounds, acrylamide, N,N-dimethylformamide and N,N-dimethylacetamide, in soil and sediment, comprising the following steps: Step 1. Sample collection and storage: Soil and sediment samples were collected and stored in clean brown glass bottles; During transportation, samples should be refrigerated, protected from light, and sealed. If they cannot be analyzed and measured in time, they should be refrigerated below 4°C and protected from light. Step 2, sample preparation: put the sample on a porcelain plate or stainless steel plate, mix it, remove foreign matter, take an appropriate amount of the mixed sample and put it in a vacuum freeze dryer for dehydration; after drying, grind, sieve, and homogenize it into particles for standby use; Step 3, sample extraction, purification and concentration: weigh 2.00±0.01g of freeze-dried soil sample, place in a 50mL polyethylene centrifuge tube, add 2-10mL methanol, seal and mix with a vortex mixer; after ultrasonic extraction for 10-60 minutes, centrifuge at 6000 rpm for 10 minutes, take 1mL of sample and filter into a sample vial for testing; Step 4, liquid chromatography-triple quadrupole mass spectrometer conditions: liquid phase conditions are that the mobile phase (A) is 0% to 0.02% formic acid water, the mobile phase is (B) methanol, wherein the mobile phase (A): mobile phase (B) = 1:3 to 2:1; flow rate: 0.1 to 0.8 mL / min; injection volume: 5.0 μL; column temperature: 10 to 70° C.; The triple quadrupole mass spectrometry conditions were as follows: ion source: ESI+; nebulizer gas flow rate: 1-8 L / min; drying gas flow rate: 10 L / min; DL temperature: 270°C; interface temperature: 250-350°C; detection method: multiple reaction monitoring; Step 5, standard curve establishment: pipette amide mixed standard solutions with concentrations of 0 μg / L, 10 μg / L, 20 μg / L, 50 μg / L, 100 μg / L, and 200 μg / L, respectively, and analyze them in sequence from low concentration to high concentration according to the instrument conditions in step 4, record the chromatographic peak area, and plot the three amide compounds in the linear range with the peak area of ​​the chromatographic peak as the ordinate and the target concentration as the abscissa to draw a standard working curve; Step 6, sample determination: set the liquid chromatography-triple quadrupole mass spectrometer conditions according to step 4, and after the conditions are stable, send the extracted concentrate after volume adjustment in step 3 into the liquid chromatograph through an automatic sampler for separation and detection by a mass spectrometer detector, and perform qualitative analysis based on retention time and characteristic ions and quantitative analysis based on external standard method; Step 7, result calculation: According to the peak area of ​​amide compounds measured by liquid chromatography-triple quadrupole mass spectrometry, the concentration of amide compounds in the extract is calculated using the standard curve equation, and then the concentration of the amide compounds to be tested in the soil / sediment sample is calculated based on the sample sampling amount.

2. The method according to claim 1, characterized in that In the step 3, the methanol extraction volume is 5 mL, and the extraction is performed by ultrasonication for 30 minutes after sealing.

3. The method according to claim 1, characterized in that: The mobile phase (A) of the liquid phase in step 4 is 0.005% formic acid water, mobile phase (A): mobile phase (B) = 2:3, the flow rate is 0.3 mL / min, and the column temperature is 40°C; the nebulizer gas flow rate of the triple quadrupole mass spectrometer is 3 L / min, and the interface temperature is 300°C.

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