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Measurement method for the cypermethrin pesticide residue in tea

A technology for pesticide residues and cypermethrin, which is applied in the field of determination of cypermethrin pesticide residues in tea, can solve the problems of complex tea composition and can not fully meet the actual needs of tea pesticide residues, and achieves good effect, simple extraction method and integral processing. easy effect

Inactive Publication Date: 2016-03-23
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 cypermethrin 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 cypermethrin: 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 of mixed internal standard Working solution (mirex), shake vigorously for 1min, add 4g anhydrous magnesium sulfate, 1g sodium chloride, 1g sodium citrate, 0.5g disodium hydrogen citrate and 5mL toluene, immediately shake for 2min by hand, then centrifuge at 4000rpm for 10min ;

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

Embodiment 2

[0035] The determination method of cypermethrin 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 cypermethrin: 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 of mixed internal standard Working solution (Mirex), shake vigorously for 2 minutes, add 4g anhydrous magnesium sulfate, 1g sodium chloride, 1g sodium citrate, 0.5g disodium hydrogen citrate and 5mL toluene, shake immediately by hand for 2 minutes, then centrifuge at 3000rpm for 15 minutes ;

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

Embodiment 3

[0043] The determination method of cypermethrin 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 cypermethrin: 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 of mixed internal standard Working solution (Mirex), shake vigorously for 2 minutes, add 4g anhydrous magnesium sulfate, 1g sodium chloride, 1g sodium citrate, 0.5g disodium hydrogen citrate and 5mL toluene, shake immediately by hand for 3 minutes, then centrifuge at 5000rpm for 5 minutes ;

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

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Abstract

The invention relates to a measurement method for the cypermethrin pesticide residue in tea. The method comprises the following steps: firstly, sample preparation is carried out, namely, tea is dried, ground and sieved; secondly, cypermethrin crude extraction is carried out, namely, the tea powder is placed in a centrifuge tube, water is added for infiltration, petroleum ether and a mixed internal standard operating fluid are added, the mixture is shocked and mixed uniformly, anhydrous magnesium sulfate, sodium chloride, sodium citrate, sodium hydrogencitrate and methylbenzene are added, and the mixture is shocked uniformly and centrifuged; thirdly, cypermethrin crude extract product purifying is carried out, namely, the supernate is taken and placed in a centrifuge tube, anhydrous magnesium sulfate and N-propylethylenediamine bonding solid adsorbents are added, the mixture is shocked uniformly and centrifuged; fourthly, cypermethrin extraction is carried out, namely, the supernate is taken, extraction, condensation and filtering are carried out in a Florisil column by utilization of the toluene-isooctane mixed solution; fifthly, chromatographic detection is carried out. The extraction method is simple, the effects are good, and result integration processing is simple and accurate. The average recovery rate of the method is 93.21%-103.75%, the relative standard deviation is 3.28%-6.20%, the average recovery rate and the relative standard deviation meet requirements and the method 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 determining the residual amount of cypermethrin 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...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N30/88
CPCG01N30/88
Inventor 周德志
Owner 周德志
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