CN113325119A

CN113325119A - Pesticide residue sample pretreatment concentration method

Info

Publication number: CN113325119A
Application number: CN202110653387.0A
Authority: CN
Inventors: 马智玲; 严程明; 乔健; 魏长宾
Original assignee: South Subtropical Crops Research Institute CATAS
Current assignee: South Subtropical Crops Research Institute CATAS
Priority date: 2021-06-11
Filing date: 2021-06-11
Publication date: 2021-08-31
Anticipated expiration: 2041-06-11
Also published as: CN113325119B

Abstract

The invention discloses a pretreatment concentration method of a pesticide residue sample, which belongs to the technical field of pesticide detection, and combines a QuEChERS method and a DLLME method to carry out pretreatment concentration on the pesticide residue sample.

Description

Pesticide residue sample pretreatment concentration method

Technical Field

The invention relates to the technical field of pesticide detection, in particular to a method for pre-treating and concentrating a pesticide residue sample.

Background

The pretreatment of the sample is the most important step in the analysis process of pesticide residues in vegetables and fruits, and the purpose of the pretreatment is not only to separate a target compound from a complex matrix, but also to reduce or eliminate the interference of other components through purification, and simultaneously to concentrate an analyte so as to realize accurate determination of trace residues. Reported sample pretreatment methods for treating vegetables and fruits with multiple pesticide residues comprise traditional liquid-liquid extraction (LLE) (rezaeeet al, 2006), solid-phase extraction (SPE) (Nagarajuetal, 2007) and the like, the treatment processes of the traditional liquid-liquid extraction (LLE) (rezaeeet al, 2006) and the solid-phase extraction (SPE) (Nagarajuetal, 2007) are long in time consumption, low in efficiency and high in labor intensity, a large amount of organic solvents which are toxic and harmful to human bodies and the environment are required to be used, the purification steps of the SPE are complicated, and the cost of purifying small columns is high. Therefore, the development of a new sample pretreatment technology which is time-saving, efficient, low in organic solvent consumption, cheap and environment-friendly has become one of the hotspots of analytical chemistry research. In recent years, various novel sample pretreatment technologies, such as Solid Phase Microextraction (SPME) (arturetal, 1990), Liquid Phase Microextraction (LPME) (Saraf raz-Yazdietal, 2010), etc., have been developed, and the microextraction technology has the greatest advantage of achieving micro-upgrading without using solvents or toxic solvents, and has been taken as an environment-friendly sample pretreatment technology to meet the current requirements of green chemical development.

Compared with SPME, LPME has the advantages of low cost and high extraction efficiency, and has been widely applied to the fields of environment, food, spice, medicine, biological analysis and the like (Raynie, 2006). LPME can now be divided into, according to the mode of operation: single Droplet Microextraction (SDME), hollow fiber membrane-based liquid phase microextraction (HF-LPME), dispersion liquid microextraction (DLLME), and the like (wangtal, 2010). The method is based on a triple solvent system, an extractant and a dispersing agent are mixed and then are quickly injected into a water sample, an emulsion system (the extractant/the water sample/the dispersing agent) is formed by slight shaking, small particles of the extractant are uniformly dispersed in the water phase at the moment, the small particles of the extractant have a larger contact area with an object to be detected, the object to be detected can be quickly transferred from the water phase to an organic phase and reach two-phase balance, and finally, through centrifugation, tiny particles of the extractant are precipitated at the bottom of a centrifugal tube, and a certain amount of precipitated phase is absorbed and then is directly subjected to sample injection analysis. According to the type of the extracting agent and the different extraction modes, the commonly used dispersion liquid-liquid micro-extraction at the present stage comprises the following steps: conventional dispersion liquid-liquid microextraction, ionic liquid dispersion liquid-liquid microextraction, suspension solidification dispersion liquid-liquid microextraction, temperature control type dispersion liquid-liquid microextraction, ultrasonic emulsification type dispersion liquid-liquid microextraction and other modes. The micro-extraction of dispersion liquid integrates sampling, extraction and concentration, and has the advantages of simple and rapid operation, low cost, small using amount of organic solvent, environmental friendliness, short extraction time, high enrichment efficiency, flexible and various forms and the like, so that the micro-extraction of dispersion liquid becomes a popular sample pretreatment technology (rezaeeet al, 2010). The DLLME method has the main disadvantages that the analyzed sample is not purified, impurities of the concentrated organic solvent are concentrated, particularly, when trace components in a complex sample (such as soil) are analyzed, matrix interference is very obvious (Wuetal, 2009), instrument consumables are seriously lost after multiple sample injections, and the maintenance frequency is increased. The application of DLLME methods most focused on the determination of contaminants in simple samples, such as organic species in liquid sample water (khodadoustat et al, 2011) and red wine (carpineteriroetal, 2012) and metals in water (afzalilet al, 2011). The high degree of concentration of DLLME methods makes it of great significance for the analysis of small, trace amounts of active or harmful ingredients that are difficult to analyze with conventional pretreatment methods, and with the advancement of research DLLME techniques have now been applied to the analysis of trace components in complex matrix samples, such as the determination of targets in biofluid urine samples (Sunetal, 2011), blood (Moinfaretal, 2009), olive oil (Daneshfaretal, 2009), fruit juice (boonhichian maetal, 2012), honey (Cheneta1, 2009), apples (Andrascikovaetal, 2012), fish meat (Hu & Lieta1, 2009), bananas (Ravelo-pee, ezeta1, 2009), tea leaves (Moinfareta1, 2009), and soil (Hu & Fu, 2009). DLLME is also combined with other pretreatment methods, such as measurement of chlorophenols in water samples by combination of DLLME with Solid Phase Extraction (SPE) (fattahjet, 2007), measurement of sulfonylurea herbicides in soil by combination of DLLME with Dispersed Solid Phase Extraction (DSPE) (Wuetal4, 2009), measurement of targets in complex matrix samples by combination of DLLME with floating organic droplet solidification technology (SPO) (matsadiqet, 2011), and combination of DLLME with Supercritical Fluid Extraction (SFE) (Rezaeeeta1, 2010). In 2007, Zhao et al developed a new method for determining 6 organophosphorus pesticide residues in solid samples of watermelon and cucumber by acetonitrile extraction, DLLME concentration and GC-ECD analysis for the first time. In 2013, Andrascikova et al used QuEChERS-DLLME-GC-MS to determine 19 kinds of pesticide residues in oranges, acetonitrile extract was mixed with carbon tetrachloride during extraction, and injected into pure water for DLLME process, in which the acetonitrile extractant was used as a dispersant in the DLLME process, but both were not applied to the purification process due to the relative simplicity of the matrix.

In 2003, the detection technology of QuEChERS pesticide multi-residue is provided by Anastassiadas and Lehotay, and the method comprises the steps of directly adding a proper amount of dispersing purificant (comprising PSA, C18, GCB and the like) into a sample extracting solution to remove interferents in a matrix, and finally separating a target object from the sample matrix through centrifugation. Compared with SPE, QuEChERS is a sample pretreatment technology with relatively small reagent dosage, simplicity, time saving, labor saving, low price, low cost and high efficiency, and the application of QuEChERS is extended to the analysis fields of pesticide and veterinary drug residues, food additives, food quality detection and the like (Norlictal, 2011). The main disadvantage of this method is that it does not have a concentration function, and for relatively low sensitivity instruments, it requires the addition of a concentration step in order to achieve sensitive measurement of trace residues. The methods reported at present for improving the sensitivity include: the sample injection amount is increased, and an expensive large-volume sample injector is required to be configured in the process; the rotary evaporation process is time-consuming and has great pollution to the environment; the nitrogen purging concentration of the sample purification liquid can greatly reduce the recovery rate of compounds with low boiling points and strong volatility, and is time-consuming, and the concentration times of the three methods are low.

Disclosure of Invention

The invention aims to provide a novel sample pretreatment method integrating purification and efficient concentration, solves the problems of high organic solvent consumption, long time consumption, more matrix interference, complicated steps and the like of the conventional method, can quickly detect residual pesticides in a sample, and has the advantages of wide application range, higher accuracy, good sensitivity and excellent recovery rate.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a pretreatment concentration method of a pesticide residue sample, which comprises the following steps: and (3) pretreating and concentrating the pesticide residue sample by combining the QuEChERS method and the DLLME method.

Further, the pretreatment concentration method of the pesticide residue sample comprises the following steps: mixing alkanol/alkanoic acid with N-propyl ethylenediamine and water, then carrying out vortex centrifugation, and taking supernate for later use; mixing the pesticide residue sample and the supernatant, homogenizing, adding an extracting agent, performing vortex for 0.5-1.5min, performing ultrasonic treatment, adding a water removing agent, performing centrifugal treatment after vortex for 2-3min, and filtering the supernatant with a 0.22-micron microporous filter membrane to obtain a first sample; and adding acetonitrile and chloroform into the first sample, uniformly mixing to form a water/acetonitrile/chloroform emulsion system, centrifuging, and collecting a precipitate phase to obtain a pesticide residue sample pretreatment concentrated product. Wherein alkanol/alkanoic acid means alkanol and/or alkanoic acid.

Further, the alkanol is one of n-octanol, n-hexanol and n-decanol.

Further, the alkanoic acid is one of n-octanoic acid, n-hexanoic acid and n-decanoic acid.

Furthermore, in the mixed system of the alkanol/alkanoic acid, the N-propyl ethylene diamine and the water, the alkanol/alkanoic acid accounts for 5-10% by volume, and the N-propyl ethylene diamine accounts for 30-40% by volume.

Further, the water removing agent is MgSO₄Sodium chloride can be added as an auxiliary water removing agent, and the mass ratio of the sodium chloride to the auxiliary water removing agent is 2: 1. the addition amount of the water removing agent is 0.5-2 wt% of the pesticide residue sample.

Further, the extractant is acetone, ethyl acetate, acetonitrile or acetonitrile containing 1% acetic acid, and the mass volume ratio of the homogenized sample to the extractant is (0.8-1.2) g: 1 mL.

Further, the ultrasonic power is 400-.

The invention discloses the following technical effects:

the pretreatment concentration method not only obviously reduces the dosage of the organic solvent, is green and environment-friendly, but also shortens the extraction time, eliminates the interference of other impurities and matrixes in the sample, and the pretreated sample can be directly used for GC-TOF/MS analysis and measurement, thereby greatly improving the sensitivity of the sample, being capable of simultaneously detecting the residues of various pesticides, having the advantages of accuracy, rapidness, simplicity, convenience, effectiveness, stability, low cost, good repeatability, high recovery rate and the like, and being suitable for the trace measurement of the pesticide residue sample. Wherein the detection limit (LOD, S/N is more than or equal to 3) and the quantification limit (LOQ, S/N is more than or equal to 10) are respectively 0.1ng/g and 0.3ng/g, and the sensitivity is higher; the relative standard deviation of the precision in the day and the precision in the day is within 7 percent, and the average accuracy is 92.75 to 115.13 percent; the average recovery rate is between 85.17% and 120.86%, and the relative standard deviation is within 6%.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The GC-TOF/MS analysis method provided by the embodiment of the invention has the following chromatographic conditions: 6890GC (Agilent Technologies, Palo Alto, Calif., USA) and Combipal were used^TMAutomatic sample injector (

AnalyticsAG, usa), the system is configured with electronically controlled split-flow non-split-flow injection ports. The chromatographic conditions for the detection were: VF-5 column (30 m. times.0.32 mm. times.0.25 μm, Agilent Inc., USA); carrier gas: helium (99.999% pure); constant flow mode, flow rate: 1.0 mL/min; and (3) sample introduction mode: no shunt sampling; sample introduction volume: 1 mu L of the solution; non-shunting time: 1 min; the temperature of a sample inlet is 250 ℃; column oven temperature program: the initial temperature is 70 deg.C (keeping for 2min), the temperature is raised to 190 deg.C at 20 deg.C/min, and then raised to 290 deg.C at 5 deg.C/min (keeping for 5 min); the total running time is 33 min; transmission line temperature: 270 ℃.

And mass spectrum part:

GCT-premier time-of-flight mass spectrometer (Waters, Manchester, UK) equipped with MassLynx4.0 workstation and NIST5.0 mass spectrum database for data acquisition and analysis and GC-MS control. Mass spectrum parameters: ionization mode: electron impact ionization (EI); bombardment energy: 70 eV; ion source temperature: 230 ℃; filament current: 200 muA; detector voltage 2800V; the quality scanning mode is full scanning; the scanning range m/z is 50-600; solvent delay time: and 5 min.

Mass spectrometry requires tuning using ammonium Perfluorotrihydrocarb (PFTBA) as an internal standard, typically using three fragment tuning instruments, mainly involving adjustment of the 68.9951 and 218.9856 peak intensity ratios, and 218.9856 and 501.9711 peak patterns, to allow the instrument to achieve higher sensitivity and resolution (at least greater than 7000FWHM), and then automatically setting the parameters through instrument guidance, where 218.9856 acts as a lock ion to correct for the exact mass number of analyte fragments during analysis.

Example 1

Mixing N-octanol, N-propyl ethylenediamine and water, then whirling for 1min, centrifuging at 8000rpm for 3min, wherein the volume ratio of the N-octanol to the N-propyl ethylenediamine to the water in a mixing system is 5%, the volume ratio of the N-propyl ethylenediamine to the water is 35%, and taking supernatant for later use; mixing 15.0g of an apple sample with the supernatant, homogenizing, adding acetone, wherein the mass volume ratio of the homogenized sample to the acetone is 0.8 g: 1mL, vortexing for 0.5min, performing ultrasonic treatment at 600w for 5min, and adding 0.5 wt% of water removing agent MgSO₄Centrifuging at 5000rpm for 2min after vortexing for 2min, and filtering the supernatant with 0.22 μm microporous membrane to obtain a first sample; adding 1mL of acetonitrile and 50 μ L of chloroform into the first sample, uniformly mixing to form a water/acetonitrile/chloroform emulsion system, centrifuging, collecting a precipitate phase to obtain a pesticide residue sample pretreatment concentrated product, transferring the pesticide residue sample pretreatment concentrated product to a microscale sample injection tube (200 μ L), placing the product in an automatic sample injection vial (2mL), and using the product for GC-TOF/MS analysis and determination.

Example 2

Mixing N-octanol/N-hexanoic acid (volume ratio is 1: 1) with N-propyl ethylenediamine and water, then whirling for 1min, centrifuging at 8000rpm for 3min, wherein the N-octanol/N-hexanoic acid accounts for 10% of the volume ratio of the N-octanol to the N-propyl ethylenediamine and the volume ratio of the N-propyl ethylenediamine accounts for 35% of the volume ratio of the N-octanol/N-hexanoic acid to the N-propyl ethylenediamine and the water, and taking supernatant for later use; mixing 15.0g of an apple sample with the supernatant, homogenizing, adding acetone, wherein the mass volume ratio of the homogenized sample to the acetone is 1.0 g: 1mL, vortexing for 0.5min, performing ultrasonic treatment at 600w for 5min, and adding 0.5 wt% of water removing agent MgSO₄Centrifuging at 5000rpm for 2min after vortexing for 2min, and filtering the supernatant with 0.22 μm microporous membrane to obtain a first sample; adding 1mL of acetonitrile and 50 mu L of chloroform into the first sample, uniformly mixing to form a water/acetonitrile/chloroform emulsion system, centrifuging, collecting a precipitate phase to obtain a pesticide residue sample pretreatment concentrated product, transferring the pesticide residue sample pretreatment concentrated product to a microscale sample injection tube (200 mu L), and then placing the product in an automatic sample injection vial (200 mu L)2mL) for GC-TOF/MS analysis.

Example 3

Mixing N-hexanol/N-decanoic acid (volume ratio is 1: 1) with N-propylethylenediamine and water, then whirling for 1min, centrifuging at 8000rpm for 3min, wherein N-octanol accounts for 10% and N-propylethylenediamine accounts for 40% in a mixed system of N-hexanol/N-decanoic acid, N-propylethylenediamine and water, and taking supernatant for later use; mixing 15.0g of apple sample with the supernatant, homogenizing, adding acetonitrile containing 1% acetic acid, wherein the mass volume ratio of the homogenized sample to the acetonitrile containing 1% acetic acid is 1.2 g: 1mL, vortexing for 0.5min, performing ultrasonic treatment at 600w for 5min, and adding 0.5 wt% of water removing agent MgSO₄Centrifuging at 5000rpm for 2min after vortexing for 2min, and filtering the supernatant with 0.22 μm microporous membrane to obtain a first sample; adding 1mL of acetonitrile and 50 μ L of chloroform into the first sample, uniformly mixing to form a water/acetonitrile/chloroform emulsion system, centrifuging, collecting a precipitate phase to obtain a pesticide residue sample pretreatment concentrated product, transferring the pesticide residue sample pretreatment concentrated product to a microscale sample injection tube (200 μ L), placing the product in an automatic sample injection vial (2mL), and using the product for GC-TOF/MS analysis and determination.

Example 4

Mixing N-decanol/N-octanoic acid (volume ratio is 1: 1) with N-propyl ethylenediamine and water, then whirling for 2min, centrifuging at 8000rpm for 3min, wherein the volume ratio of N-decanol/N-octanoic acid to N-propyl ethylenediamine and water in the mixed system is 10% of N-octanol and 30% of N-propyl ethylenediamine, and taking supernatant for later use; mixing 15.0g of an apple sample with the supernatant, homogenizing, adding acetonitrile, wherein the mass volume ratio of the homogenized sample to the acetonitrile is 1.0 g: 1mL, vortexing for 0.5min, performing ultrasonic treatment at 600w for 5min, and adding 0.5 wt% of water removing agent MgSO₄Centrifuging at 5000rpm for 2min after vortexing for 2min, and filtering the supernatant with 0.22 μm microporous membrane to obtain a first sample; adding 1mL of acetonitrile and 50 mu L of chloroform into the first sample, uniformly mixing to form a water/acetonitrile/chloroform emulsion system, centrifuging, collecting a precipitate phase to obtain a pesticide residue sample pretreatment concentrated product, transferring the pesticide residue sample pretreatment concentrated product to a microscale sample injection tube (200 mu L), placing the microscale sample injection tube in an automatic sample injection vial (2mL), and using the sample injection tube for GC-TOF/MS analysis and measurementAnd (4) determining.

Example 5

Mixing N-decanol/N-octanol (volume ratio is 1: 1) with N-propyl ethylenediamine and water, then whirling for 1min, centrifuging for 3min at 8000rpm, wherein the volume ratio of N-octanol to N-propyl ethylenediamine to water in a mixing system of N-decanol/N-octanol, N-propyl ethylenediamine is 5%, and the volume ratio of N-propyl ethylenediamine is 40%, and taking supernatant for later use; mixing 15.0g of orange sample (with peel) with the supernatant, homogenizing, adding acetone, wherein the mass volume ratio of the homogenized sample to the acetone is 1.2 g: 1mL, vortex for 0.5min, ultrasonic processing for 5min at 600w, adding 1.5 wt% of water removing agent MgSO₄And NaCl (mass ratio is 2: 1), whirling for 2min, centrifuging at 5000rpm for 2min, and filtering the supernatant with 0.22 μm microporous membrane to obtain a first sample; adding 1mL of acetonitrile and 50 μ L of chloroform into the first sample, uniformly mixing to form a water/acetonitrile/chloroform emulsion system, centrifuging, collecting a precipitate phase to obtain a pesticide residue sample pretreatment concentrated product, transferring the pesticide residue sample pretreatment concentrated product to a microscale sample injection tube (200 μ L), placing the product in an automatic sample injection vial (2mL), and using the product for GC-TOF/MS analysis and determination.

Example 6

Mixing N-hexanoic acid, N-propyl ethylenediamine and water, then whirling for 1min, centrifuging at 8000rpm for 3min, wherein N-octanol accounts for 5% and N-propyl ethylenediamine accounts for 40% in a mixed system of N-hexanoic acid, N-propyl ethylenediamine and water, and taking supernatant for later use; mixing 15.0g of apple sample with the supernatant, homogenizing, adding ethyl acetate, wherein the mass volume ratio of the homogenized sample to the ethyl acetate is 1.2 g: 1mL, vortex for 0.5min, and after ultrasonic treatment for 5min at 600w, add 2 wt% of water removing agent MgSO₄Centrifuging at 5000rpm for 2min after vortexing for 2min, and filtering the supernatant with 0.22 μm microporous membrane to obtain a first sample; adding 1mL of acetonitrile and 50 μ L of chloroform into the first sample, uniformly mixing to form a water/acetonitrile/chloroform emulsion system, centrifuging, collecting a precipitate phase to obtain a pesticide residue sample pretreatment concentrated product, transferring the pesticide residue sample pretreatment concentrated product to a microscale sample injection tube (200 μ L), placing the product in an automatic sample injection vial (2mL), and using the product for GC-TOF/MS analysis and determination.

Example 7

Accurately weighing 15.0g of homogenized apple into a 100mL centrifuge tube, adding 3.0g of sodium chloride, 1.5g of anhydrous sodium acetate and 15.0mL of 1% acetic acid acetonitrile solution, homogenizing at a high speed for 1min, centrifuging at a high speed of 5000r/min for 2min, taking 2.0mL of supernatant, transferring the supernatant into a 5mL centrifuge tube filled with 100mg of PSA, 100mgC18, 300mg of anhydrous magnesium sulfate and a proper amount of GCB (the dosage of GCB is determined according to the shade of the color of a sample extracting solution), uniformly mixing by vortex, centrifuging at a speed of 5000r/min for 2min, filtering the supernatant through a 0.22 mu m microporous filter membrane, collecting in a small beaker (5mL), and concentrating by a dispersion liquid microextraction; taking 1.0mL of acetonitrile supernatant (dispersant) into a 15mL of pointed-bottom centrifugal test tube with a plug, adding 50.0 μ L of chloroform (extractant), mixing uniformly, and quickly injecting 4mL of ultrapure water into the pointed-bottom centrifugal tube; slightly shaking for 1min to form a water/acetonitrile/chloroform emulsion system, wherein small chloroform particles are uniformly dispersed in a water phase along with acetonitrile for extraction balance; centrifuging at a certain temperature (about 20 ℃) for 3min at 5000rpm, and depositing chloroform dispersed in an aqueous phase to the bottom of a centrifugal tube; the precipitated phase was finally transferred to a microtiter tube (200. mu.L) and placed in an autosampler vial (2mL) for GC-TOF/MS analytical determination.

Example 8

Mixing 15.0g of an apple sample with water, homogenizing, and adding acetone, wherein the mass volume ratio of the homogenized sample to the acetone is 1.0 g: 1mL, vortexing for 0.5min, performing ultrasonic treatment at 600w for 5min, and adding 0.5 wt% of water removing agent MgSO₄Centrifuging at 5000rpm for 2min after vortexing for 2min, and filtering the supernatant with 0.22 μm microporous membrane to obtain a first sample; adding 1mL of acetonitrile and 50 μ L of chloroform into the first sample, uniformly mixing to form a water/acetonitrile/chloroform emulsion system, centrifuging, collecting a precipitate phase to obtain a pesticide residue sample pretreatment concentrated product, transferring the pesticide residue sample pretreatment concentrated product to a microscale sample injection tube (200 μ L), placing the product in an automatic sample injection vial (2mL), and using the product for GC-TOF/MS analysis and determination.

The results of the test of example 2 are shown in Table 1. The results of examples 1 and 3 to 6 were similar to those of example 2, and the linear correlation coefficient of example 7 was 0.9981, LOD was 0.01. mu.g/kg, LOQ was 0.03. mu.g/kg, the linear correlation coefficient of example 8 was 0.9975, LOD was 0.1. mu.g/kg, and LOQ was 0.5. mu.g/kg.

TABLE 1

As is clear from Table 1, the pretreatment concentration method of the present invention has high sensitivity.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. The pretreatment concentration method for the pesticide residue sample is characterized by comprising the following steps of: and (3) pretreating and concentrating the pesticide residue sample by combining the QuEChERS method and the DLLME method.

2. The pretreatment concentration method for the pesticide residue sample according to claim 1, which is characterized by comprising the following steps: mixing alkanol/alkanoic acid with N-propyl ethylenediamine and water, then carrying out vortex centrifugation, and taking supernate for later use; mixing the pesticide residue sample with the supernatant, homogenizing, adding an extracting agent, performing vortex for 0.5-1.5min, performing ultrasonic treatment, adding a water removing agent, performing centrifugal treatment after vortex for 2-3min, and filtering the supernatant with a microporous filter membrane to obtain a first sample; and adding acetonitrile and chloroform into the first sample, uniformly mixing to form a water/acetonitrile/chloroform emulsion system, centrifuging, and collecting a precipitate phase to obtain a pesticide residue sample pretreatment concentrated product.

3. The method for pre-treating and concentrating the pesticide residue sample according to claim 2, wherein the alkanol is one of n-octanol, n-hexanol and n-decanol.

4. The method for pre-treating and concentrating the pesticide residue sample according to claim 2, wherein the alkanoic acid is one of n-octanoic acid, n-hexanoic acid and n-decanoic acid.

5. The method for pre-treating and concentrating the pesticide residue sample as claimed in claim 2, wherein the volume ratio of the alkanol/alkanoic acid to the N-propyl ethylenediamine to the water is 5-10%, and the volume ratio of the N-propyl ethylenediamine to the alkanoic acid is 30-40%.

6. The method for pre-treating and concentrating the pesticide residue sample according to claim 1, wherein the water scavenger is MgSO₄The adding amount is 0.5 wt% -2 wt% of the pesticide residue sample.

7. The method for pre-treating and concentrating the pesticide residue sample as claimed in claim 1, wherein the extractant is acetone, ethyl acetate, acetonitrile or acetonitrile containing 1% acetic acid, and the mass-to-volume ratio of the homogenized sample to the extractant is (0.8-1.2) g: 1 mL.