A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits

Abstract

The present invention provides a method for quickly extracting and purifying pyrethroid pesticide residues from vegetables and fruits, and relates to the technical field of agricultural product safety detection. The detection method comprises S1. extraction: weighing homogenized vegetable and fruit samples into a centrifuge tube, adding 0.1% acetic acid acetonitrile for extraction, and then adding sodium chloride and sodium citrate dihydrate to obtain a supernatant. S2. solvent conversion: transferring a suitable volume of supernatant into a conical flask, vacuum rotary evaporation to near dryness, drying with nitrogen, adding n-hexane to dissolve, covering the bottle with a stopper and shaking well, and waiting for QuEChers purification; S3. purification: transferring the n-hexane solution obtained by the S2 solvent conversion to a centrifuge tube containing PSA and tungsten disulfide nanomaterials, shaking and centrifuging, taking the supernatant through an organic microporous filter membrane, and providing GC-ECD determination. The detection method effectively removes impurities in the extraction solution and has a simple procedure, shortens the sample pretreatment time, reduces matrix interference, and improves the accuracy of the determination.

Description

[Technical field]

[0001] The invention relates to the technical field of agricultural product safety detection, and in particular to a method for quickly extracting and purifying pyrethroid pesticide residues from vegetables and fruits. [Background technology]

[0002] Pyrethroid pesticides are a type of synthetic insecticides, and their insecticidal toxicity is 10 to 100 times higher than that of the older generation of insecticides such as organochlorine, organophosphorus, and carbamates. Pyrethroids have a strong contact effect on insects, and some varieties also have stomach poison or fumigation effects. They have low toxicity to mammals. They are gradually replacing traditional organophosphorus pesticides. Recent studies have found that a certain residual dose can cause serious damage to the central nervous system of contacting organisms. Therefore, my country has formulated strict limit standards for pesticide residues in agricultural products such as fruits, vegetables, and food. Agricultural testing departments at all levels test the pesticide residues of local agricultural and sideline products before they are put on the market to ensure the safety of agricultural products.

[0003] For example, the search for pyrethroid pesticide residue detection research is as follows:

[0004] Chinese patent CN201010221275.X discloses a method for detecting pyrethroid pesticide residues in rice. After 4 hours of extraction with acetonitrile, the pyrethroid pesticides are fully extracted. After ultrapure water oscillation and standing for 30 minutes, the pyrethroid pesticides are separated well. After 6 minutes of centrifugal separation, the phase separation is good, so the extraction rate is high. The pyrethroid pesticides can be washed and purified with a mixed solution of n-hexane + acetone (90:10) to achieve good washing of the pyrethroid pesticides. During detection, the column temperature is programmed to 260°C at a rate of 40°C / min, and the injection temperature is 260°C, and the detector temperature is also 260°C, so that the gas chromatograph is easy to operate, the gas chromatography conditions are simple, the pyrethroid pesticides are separated and detected in a short time, and the measured value is still more accurate. Therefore, the present invention is a method for detecting pyrethroid pesticide residues in rice with a high extraction rate, simple gas chromatography conditions, low operating requirements, and a high quantitative recovery rate.

[0005] Chinese patent CN202111449318.4 provides a rapid detection method for pyrethroid pesticide residues disclosed in the present invention, comprising the following steps: (1) mixing the sample solution to be tested and the pig liver carboxylesterase solution evenly and then standing; (2) taking the solution of step (1), adding the substrate α-naphthyl acetate, and heating in a water bath; (3) taking the solution of step (2), adding a terminator and a color developer, mixing, and then adding hydrochloric acid; (4) taking the solution of step (3), and determining the absorbance value of the color product in the solution; (5) setting a blank control group to which the sample solution to be tested is not added, and determining the absorbance value b of the color product in the blank control group; (6) comparing the absorbance value a with the absorbance value b. The invention inhibits the activity of pig liver carboxylesterase by adding a test solution containing pyrethroid pesticide residues, takes α-naphthyl acetate as a reaction substrate, and uses a fast blue B salt solution as a color developer, and measures the absorbance value of the color development product. The absorbance value is used to reflect the inhibitory effect of the pyrethroid pesticide residues on the enzyme, thereby quickly detecting the pyrethroid pesticide residues in fruits and vegetables.

[0006] However, in recent years, with the increase in the amount of test samples and the heavier testing tasks, various laboratories have been establishing or adopting some rapid, high-throughput extraction and purification methods for pesticide residue pretreatment in order to improve testing efficiency and shorten analysis time.

[0007] It is well known that during the QuEChERS extraction process, a large amount of pigments in vegetables and fruits or fats and phospholipids in animal-derived samples will be extracted together with the target compounds. These co-extracts may interfere with chromatographic analysis and contaminate the injection port liner, chromatographic column and detector. Simple and effective pretreatment is particularly important. This patent adopts an improved QuEChers method for dispersed purification, which is simple and fast. [Summary of the invention]

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits comprises the following steps:

[0010] S1. Extraction: Weigh the homogenized vegetable and fruit samples into a 50 mL centrifuge tube, add 0.1% acetic acid and acetonitrile, vortex extract for 1 min, add sodium chloride and sodium citrate dihydrate, continue vortex extraction for 1 min, centrifuge at 4000 r / min for 5 min, and reserve the supernatant for later use;

[0011] S2. Solvent conversion: Transfer a suitable volume of supernatant into a conical flask, vacuum rotary evaporate to near dryness, blow dry with nitrogen, add 2.0 ml of n-hexane to dissolve, cover the bottle with a stopper and shake well, and wait for QuEChers purification;

[0012] S3. Purification: Transfer all the 2 ml n-hexane solution obtained from the solvent conversion in the above step to a centrifuge tube containing 2-6 mg ethylenediamine-N-propylsilane (PSA) and 10-25 mg tungsten disulfide nanomaterials, shake and centrifuge, and take the supernatant through an organic microporous filter membrane for GC-ECD determination.

[0013] Further, in step S1, the mass volume ratio of the homogenized fruit and vegetable sample to acetonitrile is 0.5-1 g / mL.

[0014] It is further explained that in step S1, the mass ratios of the added sodium chloride, sodium citrate dihydrate and vegetable sample are 1-1:5 and 1-2:10 respectively.

[0015] Further, in step S2, the suitable volume of the supernatant is 2.0 ml to 4.0 ml.

[0016] Further, in step S3, the shaking times are 10 to 20 times, the centrifugal speed is 3000 to 5000 r / min, and the centrifugal time is 4 to 8 min.

[0017] It is further explained that in step S3, the pore size of the organic microporous filter membrane is 0.22 μm.

[0018] Further description, in step S3, the types of pyrethroid pesticides for GC-ECD determination are bifenthrin, cypermethrin, chlorfenapyr, permethrin, cyfluthrin, cypermethrin, cypermethrin, cyvalerate, and deltamethrin.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The method of the present invention for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits adopts 0.1% acetic acid and acetonitrile for extraction, n-hexane for solvent conversion, PSA and tungsten disulfide nanomaterials for purification, which can effectively remove impurities such as sugars, fats and pigments in the extraction solution, thereby reducing the interference of gas chromatography electron capture detector detection and analysis and improving the measurement accuracy.

[0021] 2. The method of the present invention for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits adopts PSA (polyphenylsulfone terephthalamide fiber) and tungsten disulfide as purification fillers and QuEChers method for dispersed purification, which not only avoids the cumbersome and complicated procedures of traditional solid phase extraction column extraction and purification for detecting pyrethroid pesticides, effectively shortens the sample pretreatment time, but also can improve the initial concentration of the purification solution, thereby reducing matrix interference, improving the method accuracy, and ensuring the method reproducibility.

Brief Description of the Drawings

[0022] Figure 1 This is a gas chromatogram of purification by the method of Example 3 of the present invention.

[0023] Figure 2 The gas chromatogram is purified by the method of Comparative Example 1.

[0024] Figure 3 The gas chromatogram is purified by the method of Comparative Example 2.

[0025] Figure 4 The gas chromatogram is purified by the method of Comparative Example 3.

[0026] Figure 5 The gas chromatogram is purified by the method of Comparative Example 4.

[0027] Figure 6 Gas chromatogram of solid phase extraction column cleanup.

[0028] Figure 7 It is a pure standard gas chromatogram. [Specific implementation method]

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] Embodiment 1:

[0031] A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits comprises the following steps:

[0032] S1. Extraction: Weigh 10 g of homogenized vegetable and fruit samples into a 50 mL centrifuge tube, add 20 mL of 0.1% acetic acid and acetonitrile, vortex extract for 1 min, add 1 g of sodium chloride and 2 g of sodium citrate dihydrate, continue vortex extraction for 1 min, centrifuge at 4000 r / min for 5 min, and reserve the supernatant;

[0033] S2. Solvent conversion: Pipette 4.0 ml of the supernatant into a conical flask, vacuum rotary evaporate to dryness, blow dry with nitrogen, add 2.0 ml of n-hexane to dissolve, cover the bottle with a stopper and shake well, and wait for QuEChers purification;

[0034] S3. Purification: Transfer all 2 ml of n-hexane solution obtained from the solvent conversion in the above step to a centrifuge tube containing 2 mg of ethylenediamine-N-propylsilane (PSA) and 10 mg of tungsten disulfide nanomaterials, shake 10 times, centrifuge at 3000 r / min for 4 min, take the supernatant and pass it through an organic microporous filter membrane for GC-ECD determination.

[0035] Embodiment 2:

[0036] A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits comprises the following steps:

[0037] S1. Extraction: Weigh 10 g of homogenized vegetable and fruit samples into a 50 mL centrifuge tube, add 20 mL of 0.1% acetic acid and acetonitrile, vortex extract for 1 min, add 1 g of sodium chloride and 2 g of sodium citrate dihydrate, continue vortex extraction for 1 min, centrifuge at 4000 r / min for 5 min, and reserve the supernatant;

[0038] S2. Solvent conversion: Pipette 3.0 ml of the supernatant into a conical flask, vacuum rotary evaporate to dryness, blow dry with nitrogen, add 2.0 ml of n-hexane to dissolve, cover the bottle with a stopper and shake well, and wait for QuEChers purification;

[0039] S3. Purification: Transfer all 2 ml of n-hexane solution obtained from the solvent conversion in the above step to a centrifuge tube containing 4 mg of ethylenediamine-N-propylsilane (PSA) and 20 mg of tungsten disulfide nanomaterials, shake 15 times, centrifuge at 5000 r / min for 6 min, take the supernatant and pass it through an organic microporous filter membrane for GC-ECD determination.

[0040] Embodiment 3:

[0041] A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits comprises the following steps:

[0042] S1. Extraction: Weigh 10 g of homogenized vegetable and fruit samples into a 50 mL centrifuge tube, add 20 mL of 0.1% acetic acid and acetonitrile, vortex extract for 1 min, add 1 g of sodium chloride and 2 g of sodium citrate dihydrate, continue vortex extraction for 1 min, centrifuge at 4000 r / min for 5 min, and reserve the supernatant;

[0043] S2. Solvent conversion: Pipette 2.0 ml of the supernatant into a conical flask, vacuum rotary evaporate to near dryness, blow dry with nitrogen, add 2.0 ml of n-hexane to dissolve, cover the bottle with a stopper and shake well, and wait for QuEChers purification;

[0044] S3. Purification: Transfer all the 2 ml n-hexane solution obtained from the solvent conversion in the above step to a centrifuge tube containing 6 mg ethylenediamine-N-propylsilane (PSA) and 25 mg tungsten disulfide nanomaterials, shake 20 times, centrifuge at 4000 r / min for 8 min, take the supernatant and pass it through an organic microporous filter membrane for GC-ECD determination.

[0045] Comparative Example 1:

[0046] A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits comprises the following steps:

[0047] S1. Extraction: Weigh 10 g of homogenized vegetable and fruit samples into a 50 mL centrifuge tube, add 20 mL of 0.1% acetic acid and acetonitrile, vortex extract for 1 min, add 1 g of sodium chloride and 2 g of sodium citrate dihydrate, continue vortex extraction for 1 min, centrifuge at 4000 r / min for 5 min, and reserve the supernatant;

[0048] S2. Solvent conversion: Pipette 3.0 ml of the supernatant into a conical flask, vacuum rotary evaporate to dryness, blow dry with nitrogen, add 2.0 ml of n-hexane to dissolve, cover the bottle with a stopper and shake well, and wait for QuEChers purification;

[0049] S3. Purification: Transfer all 2 ml of n-hexane solution obtained from the solvent conversion in the above step to a centrifuge tube containing 6 mg of ethylenediamine-N-propylsilane (PSA) material, shake 20 times, centrifuge at 4000 r / min for 5 min, take the supernatant and pass it through an organic microporous filter membrane for GC-ECD determination.

[0050] Comparative Example 2:

[0051] A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits comprises the following steps:

[0052] S1. Extraction: Weigh 10 g of homogenized vegetable and fruit samples into a 50 mL centrifuge tube, add 20 mL of 0.1% acetic acid and acetonitrile, vortex extract for 1 min, add 1 g of sodium chloride and 2 g of sodium citrate dihydrate, continue vortex extraction for 1 min, centrifuge at 4000 r / min for 5 min, and reserve the supernatant;

[0053] S2. Solvent conversion: Pipette 3.0 ml of the supernatant into a conical flask, vacuum rotary evaporate to dryness, blow dry with nitrogen, add 2.0 ml of n-hexane to dissolve, cover the bottle with a stopper and shake well, and wait for QuEChers purification;

[0054] S3. Purification: Transfer all 2 ml of n-hexane solution obtained by solvent conversion in the above step to a centrifuge tube containing 20 mg of tungsten disulfide nanomaterials, shake 20 times, centrifuge at 4000 r / min for 5 min, take the supernatant and pass it through an organic microporous filter membrane for GC-ECD determination.

[0055] Comparative Example 3:

[0056] A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits comprises the following steps:

[0057] S1. Extraction: Weigh 10 g of homogenized vegetable and fruit samples into a 50 mL centrifuge tube, add 20 mL of 0.1% acetic acid and acetonitrile, vortex extract for 1 min, add 1 g of sodium chloride and 2 g of sodium citrate dihydrate, continue vortex extraction for 1 min, centrifuge at 4000 r / min for 5 min, and reserve the supernatant;

[0058] S2. Purification: Pipette 2 ml of supernatant into a centrifuge tube containing 6 mg of ethylenediamine-N-propylsilane (PSA) and 25 mg of tungsten disulfide nanomaterials, shake 20 times, centrifuge at 4000 r / min for 5 min, and take the supernatant to pass through an organic microporous filter membrane for GC-ECD determination.

[0059] Comparative Example 4:

[0060] A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits comprises the following steps:

[0061] S1. Extraction: Weigh 10 g of homogenized vegetable and fruit samples into a 50 mL centrifuge tube, add 20 mL of 0.1% acetic acid and acetonitrile, vortex extract for 1 min, add 1 g of sodium chloride and 2 g of sodium citrate dihydrate, continue vortex extraction for 1 min, centrifuge at 4000 r / min for 5 min, and reserve the supernatant;

[0062] S2. Purification: Pipette 2 ml of supernatant into a centrifuge tube containing 20 mg of graphitized carbon black (GCB) material, shake 20 times, centrifuge at 4000 r / min for 5 min, and take the supernatant to pass through an organic microporous filter membrane for GC-ECD determination.

[0063] Experimental verification:

[0064] (1) Preparation of standard solution: Use chromatographic grade n-hexane to prepare a 100 mg L -1 The standard solutions of pyrethroid pesticides were stored at -20 °C before use. The standard working solutions were prepared by diluting the stock solutions with n-hexane.

[0065] (2) Dilute the standard solution with n-hexane to make working solutions of different concentrations (0.05 mg L -1 ~2mg L -1 ) and then the measurements were carried out separately: each concentration was measured in parallel 3 times to obtain the linear equation and correlation coefficient of pyrethroid pesticides.

[0066] (3) The methods for rapid extraction and purification of pyrethroid pesticide residues of Examples 1 to 3 and Comparative Examples 1 to 4 were respectively used for extraction, purification and determination, and the average recovery rate and RSD were calculated, as shown in Table 1.

[0067] Table 1 Experimental results

[0068] project Recovery rate (%) RSD / % (n=3 in one day) Example 1 95.8 4.5 Example 2 95.4 4.7 Example 3 96.6 4.6 Comparative Example 1 58.8 4.8 Comparative Example 2 76.8 4.7 Comparative Example 3 66.2 4.6 Comparative Example 4 54.2 4.9

[0069] It can be seen from Examples 1 to 3, Comparative Examples 1 to 4, and Experimental Examples that the method of the present invention for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits can not only effectively shorten the sample pretreatment time, but also effectively remove matrix interference, thereby improving the sensitivity and accuracy of the method. The method is simple, rapid, and effective.

[0070] Figures 1 to 5 The gas chromatograms of Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 are respectively; Figure 6 The gas chromatogram of the same sample extraction solution purified and determined according to the solid phase extraction column purification method of the Ministry of Agriculture standard NY / T 761-2008 "Determination of organophosphorus, organochlorine, pyrethroid and carbamate pesticide residues in vegetables and fruits" (the purification process mainly includes the activation of the solid phase extraction column, loading after solvent conversion, elution, rotary evaporation, constant volume and other processes, which takes 20 to 40 minutes); Figure 7 This is the gas chromatogram of the pure standard solution of the same concentration. Figure 7 and Figure 2 to Figure 5 It can be seen that the peaks of the chromatograms obtained in Comparative Examples 1 and 4 are relatively small, and the recovery rates are both lower than 60%, and Comparative Example 1 has a large matrix interference; the matrix interference of the chromatograms obtained in Comparative Examples 2 and 3 is small, but Comparative Example 3 is directly purified by acetonitrile extraction solution and then measured on the machine. Since acetonitrile has a large damage to the gas chromatography column, excessive use will reduce the column efficiency. The recovery rate of Comparative Example 2 is lower than 80%, and the recovery rate of Comparative Example 2 is lower than 80%. Figure 1 and Figure 6 It can be seen that Example 3 and the traditional solid phase extraction column purification method have no matrix interference on the target object to be measured, and the recovery rates of the two methods are both greater than 90%. However, the sample extraction solution purification process of Example 3 takes 5 to 15 minutes, which is significantly better than the solid phase extraction column purification method.

[0071] The above description is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the creative concept of the present invention, several improvements and changes are made, which all fall within the protection scope of the present invention.

Claims

1. A method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits, characterized in that: The following steps are involved: S1. Extraction: Weigh the homogenized vegetable and fruit samples into a 50 mL centrifuge tube, add 0.1% acetic acid and acetonitrile, vortex extract for 1 min, add sodium chloride and sodium citrate dihydrate, continue vortex extraction for 1 min, centrifuge at 4000 r / min for 5 min, and keep the supernatant for later use; S2. Solvent conversion: transfer a suitable volume of supernatant into a conical flask, vacuum rotary evaporate to near dryness, blow dry with nitrogen, add 2.0 ml of n-hexane to dissolve, cover the flask with a stopper and shake well, and wait for QuEChers purification; S3. Purification: Transfer all 2 ml of n-hexane solution obtained from the solvent conversion in the above step to a centrifuge tube containing 2-6 mg of ethylenediamine-N-propylsilane and 10-25 mg of tungsten disulfide nanomaterials, shake and centrifuge, and take the supernatant to pass through an organic microporous filter membrane for GC-ECD determination.

2. The method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits according to claim 1, characterized in that: In step S1, the mass volume ratio of the homogenized vegetable or fruit sample to acetonitrile is 0.5 to 1 g / mL.

3. The method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits according to claim 1, characterized in that: In step S1, the mass ratios of the added sodium chloride, sodium citrate dihydrate and vegetable and fruit samples are 1-1:5 and 1-2:10 respectively.

4. The method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits according to claim 1, characterized in that: In step S2, the suitable volume of the supernatant is 2.0 ml to 4.0 ml.

5. The method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits according to claim 1, characterized in that: In step S3, the shaking frequency is 10 to 20 times, the centrifugal speed is 3000 to 5000 r / min, and the centrifugal time is 4 to 8 min.

6. The method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits according to claim 1, characterized in that: In step S3, the pore size of the organic microporous filter membrane is 0.22 μm.

7. The method for rapidly extracting and purifying pyrethroid pesticide residues from vegetables and fruits according to claim 1, characterized in that: In step S3, the types of pyrethroid pesticides for GC-ECD determination are bifenthrin, cypermethrin, cyhalothrin, permethrin, cyfluthrin, cypermethrin, cypermethrin, cyvalerate, and deltamethrin.

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