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Method for determining tefluthrin pesticide residue in tea

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

Inactive Publication Date: 2016-05-04
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 determination method of tefluthrin pesticide residue in tea 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 tefluthrin: 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 stand for 10min, add 10mL of petroleum ether and 1mL Mix the 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, shake immediately by hand for 2min, and then Centrifuge at 4000rpm for 10min;

[0030] (3) Purification of the crude extract of tefluthrin: Take 5 mL of the supernatant...

Embodiment 2

[0035] The determination method of tefluthrin pesticide residue in tea 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 tefluthrin: 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 stand for 5min, add 12mL of petroleum ether and 1mL Mix the internal standard working solution (mirex), shake vigorously for 2 minutes, 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 2 minutes, and then Centrifuge at 3000rpm for 15min;

[0038] (3) Purification of crude tefluthrin extract: Take 5 mL of the supernata...

Embodiment 3

[0043] The determination method of tefluthrin pesticide residue in tea 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 tefluthrin: 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 stand for 15min, add 8mL of petroleum ether and 1mL Mix the internal standard working solution (mirex), shake vigorously for 2 minutes, 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 for 3 minutes by hand, and then Centrifuge at 5000rpm for 5min;

[0046] (3) Purification of crude tefluthrin extract: Take 5 mL of the supernatant in step (2) i...

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Abstract

The invention relates to a method for determining tefluthrin pesticide residue in tea. The method comprises the following steps: (1) preparing a sample: drying tea, grinding and sieving; (2) roughly extracting tefluthrin: putting the tea powder in a centrifugal tube, adding water for wetting, adding petroleum ether and mixing an internal standard working solution, uniformly shaking, adding anhydrous magnesium sulfate, sodium chloride, sodium citrate, sodium hydrogen citrate and methylbenzene, uniformly shaking and centrifuging; (3) purifying crude extract of tefluthrin: taking liquid supernatant and putting into the centrifugal tube, adding anhydrous magnesium sulfate and N-propyl quadrol bonding solid phase adsorbent, uniformly shaking and centrifuging; (4) extracting tefluthrin: taking the liquid supernatant and taking a methylbenzene-isooctane mixed solution for extracting, concentrating and filtering on a Florisil column; and (5) performing chromatography detection. The extraction method provided by the invention is simple and good in effect; the result integral treatment is more convenient and accurate; and the method provided by the invention has the average recovery rate of 93.21%-103.75% and the relative standard deviation of 3.28%-6.20%, thereby meeting requirements and being 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 measuring tefluthrin pesticide residues 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 broad-spectrum...

Claims

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Application Information

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IPC IPC(8): G01N30/02G01N30/06G01N30/08
CPCG01N30/02G01N30/06G01N30/08G01N2030/025G01N2030/062
Inventor 周德志
Owner 周德志
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