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Method for detecting residual amount of permethrin pesticide in tea leaves

A technology for pesticide residues and permethrin, which is applied in the field of pesticide detection, can solve the problems that the actual needs of pesticide residues in tea cannot be fully met, and the composition of tea leaves is complex, and achieves the effects of good effect, simple extraction method, and simple integration processing.

Inactive Publication Date: 2016-03-16
周德志
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the complexity of tea ingredients, theophylline, tea pigments, polyphenols, and lipids interfere with the determination, so the national testing standards cannot fully meet the actual needs of tea pesticide residues

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] The method for detecting the amount of permethrin pesticide residues in tea leaves comprises the following steps:

[0028] (1) Sample preparation: put the tea leaves in an oven, keep them at 50°C for 2 hours, and dry them with a moisture content of 5%. Grind the samples and pass them through a 2mm sieve. Note that the grinding temperature should not exceed 50°C.

[0029] (2) Crude extraction of permethrin: put 2g of tea powder in a 50mL centrifuge tube, accurate to 0.01g, add 10mL of deionized water, shake until the sample is fully infiltrated by water, let it stand for 10min, add 10mL of petroleum ether and 1mL to mix Internal standard working solution (mirex), shake vigorously for 1min, add 4g of anhydrous magnesium sulfate, 1g of sodium chloride, 1g of sodium citrate, 0.5g of disodium hydrogen citrate and 5mL of toluene, immediately shake by hand for 2min, then shake at 4000rpm Centrifuge for 10 minutes;

[0030] (3) Purification of crude permethrin extract: Take 5 ...

Embodiment 2

[0035] The method for detecting the amount of permethrin pesticide residues in tea leaves comprises the following steps:

[0036] (1) Sample preparation: put the tea leaves in an oven, keep them at 45°C for 3 hours, and dry them with a moisture content of 6%. Grind the samples and pass them through a 1mm sieve. Note that the grinding temperature should not exceed 50°C.

[0037] (2) Crude extraction of permethrin: put 3g of tea powder in a 50mL centrifuge tube, accurate to 0.01g, add 10mL of deionized water, shake until the sample is fully infiltrated by water, let it stand for 5min, add 12mL of petroleum ether and 1mL to mix Internal standard working solution (mirex), shake vigorously for 2min, add 4g of anhydrous magnesium sulfate, 1g of sodium chloride, 1g of sodium citrate, 0.5g of disodium hydrogen citrate and 5mL of toluene, shake immediately by hand for 2min, then at 3000rpm Centrifuge for 15 minutes;

[0038] (3) Purification of crude permethrin extract: Take 5 mL of t...

Embodiment 3

[0043] The method for detecting the amount of permethrin pesticide residues in tea leaves comprises the following steps:

[0044] (1) Sample preparation: put the tea in an oven, keep it at 55°C for 1 hour, and dry it with a moisture content of 4%. Grind the sample and pass it through a 3mm sieve. Note that the grinding temperature should not exceed 50°C.

[0045] (2) Crude extraction of permethrin: put 1g of tea powder in a 50mL centrifuge tube, accurate to 0.01g, add 10mL of deionized water, shake until the sample is fully infiltrated by water, let it stand for 15min, add 8mL of petroleum ether and 1mL to mix Internal standard working solution (mirex), shake vigorously for 2min, add 4g of anhydrous magnesium sulfate, 1g of sodium chloride, 1g of sodium citrate, 0.5g of disodium hydrogen citrate and 5mL of toluene, shake immediately by hand for 3min, then shake at 5000rpm Centrifuge for 5min;

[0046] (3) Purification of the crude permethrin extract: Take 5 mL of the supernat...

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PUM

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Abstract

The invention relates to a method for determining the residual quantity of a permethrin pesticide in tea leaves. The method comprises the following steps: 1, preparing a sample: drying the tea leaves, grinding the dried tea leaves, and sieving the ground tea leaves; 2, carrying out permethrin crude extraction: placing the powdered tea leaves in a centrifuge tube, adding water to infiltrate the powdered tea leaves, adding petroleum ether and a mixed internal standard operating fluid, vibrating until uniformity, adding anhydrous magnesium sulfate, sodium chloride, sodium citrate, disodium hydrogen citrate and toluene, vibrating until uniformity, and centrifuging; 3, purifying a permethrin crude extraction product: taking a supernatant obtained in step 2 to the centrifuge tube, adding anhydrous magnesium sulfate and an N-propylethylene diamine bonded solid phase adsorbent, vibrating until uniformity, and centrifuging; 4, carrying out permethrin extraction: taking a supernatant obtained in step 3, carrying out Florisil silica column extraction by using a toluene-isooctane mixed solution, concentrating, and filtering; and 5, carrying out chromatographic detection. The extraction method has the advantages of simplicity, good effect, and simple and accurate result integration treatment. The average recovery rate of the method is 93.21-103.75%, and the relative standard deviation is 3.28-6.20%, so the method accords with requirements, and is accurate and reliable.

Description

technical field [0001] The invention belongs to the technical field of pesticide detection, and in particular relates to a method for detecting the residual amount of permethrin pesticide in tea leaves. Background technique [0002] Tea is a traditional economic crop that earns foreign exchange through export in my country. In recent years, with the widespread spread of the concept of green food, its inherent quality, hygiene and safety issues have increasingly attracted people's attention, and it has also become a technical barrier in international trade. In particular, the European Union promulgated a batch of maximum pesticide residue (MRL) standards in food on August 27, 2004, which included 168 tea pesticide residue standards. The number of tea testing items has increased a lot compared with the past, the maximum pesticide residue value has been greatly reduced, and the limit standards have become increasingly stringent. [0003] Pyrethroid insecticides are a class of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N30/02
CPCG01N30/02G01N2030/025
Inventor 周德志
Owner 周德志
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