Rapid Quantitative Detection Method of Cyanopyrethroid Pesticide Residues in Tea

A quantitative detection method and pyrethroid technology are applied in the preparation of test samples, material analysis by observing the influence of chemical indicators, and analysis by chemical reaction of materials, etc., which can solve the high cost and technical requirements. high, time-consuming and other problems, to achieve the effects of good stability, high sensitivity and thorough pesticide reaction

Inactive Publication Date: 2011-11-30
HUAZHONG AGRI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The purpose of the present invention is to provide a method for quickly detecting the residues of cyano-pyrethroid pesticides in tea leaves, so as to solve the disadvantages of the prior art and overcome the ...

Method used

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  • Rapid Quantitative Detection Method of Cyanopyrethroid Pesticide Residues in Tea
  • Rapid Quantitative Detection Method of Cyanopyrethroid Pesticide Residues in Tea
  • Rapid Quantitative Detection Method of Cyanopyrethroid Pesticide Residues in Tea

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Take the dry tea obtained from the tea science base of Huazhong Agricultural University as the raw material, weigh 3g and grind it with a mortar, put it into a 50ml triangular flask, add reagent 1, and ultrasonic (KQ-300DZ digitally controlled ultrasonic) Extract for 15 minutes; use cotton to filter the extract into the reaction device (3); wash the filter residue twice with reagent one, and combine the filtrate; add reagent two to the three-necked bottle, connect the device (see attached figure), close the valve (6), and open Valve (5), open (TH-110B atmospheric sampler) (8), stir in a water bath at 65°C (DF-101S collector type constant temperature heating magnetic stirrer), pump air for 6 minutes; open valve (6), close the valve (5), add reagent 3 through the addition funnel (2), pump air and collect for 10 min; turn off the pump (8), take off the collection bottle (7) and add reagent 4 and reagent 5, add reagent 6 after standing for 3 min, and react for 30 min Colori...

Embodiment 2

[0035] Example 2: selection of conditions for exclusion of interfering components in tea

[0036] Like the method in Example 1, different pretreatment processes were adopted for the tea samples, and it is expected to eliminate the interfering components in the tea leaves. The results are shown in Table 2, and a preliminary judgment has been made on the basic properties of the interfering components in the tea itself, that is, they are less polar and need to be reacted with alkali to generate HCN gas by adding acid. Through petroleum ether leaching treatment, the leaching and hydrolysis reactions are separated, the interfering components in the tea itself are eliminated, and the false positive problem of the detection of cyanopyrethroid-containing pesticide residues in the tea is solved, so that it can be clearly seen by the naked eye through the color change Qualitative judgment also enhances the accuracy of quantitative detection.

[0037] Table 2 Comparison of the effects o...

Embodiment 3

[0041] Example 3: Influence of carrier gas quality on detection effect

[0042] As in the method of Example 1, when pumping air to transfer HCN gas, nitrogen purging, adding a gas washing bottle before the air pumping device, and directly pumping air were used respectively. as attached figure 1 , 5% sodium hydroxide is filled into the washing bottle at the front end of the reaction device to filter the interfering gas in the air. The measured results are shown in Table 3. The air pumping method by adding a gas washing bottle can not only achieve the same effect as nitrogen purging, but also simplify the device, reduce the cost, and be easy to popularize and apply.

[0043] Table 3 The influence of different carrier gases on the detection effect (absorbance)

[0044]

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PUM

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Abstract

The invention relates to a method for quickly detecting pesticide residue of cyanogens-containing synthetic pyrethroids in tea. The method comprises the following steps of: leaching cyanogens-containing synthetic pyrethroids in tea in advance; removing interference components in the tea and then heating the pesticide residue of cyanogens-containing synthetic pyrethroids for full alkaline hydrolysis to generate cryanide ions; adding acid to generate HCN (Hydrocyanic Acid) gas; transferring, absorbing and measuring the concentration of a CN (Cyanide) ion by using an air suction device; and realizing accurate quantitative measurement by using thiocyanate-isonicotinic acid pyrazolone spectrophotometry development. According to the method, an alkaline hydrolysis reaction and HCN gas transfer are thoroughly realized by heating, stirring and extracting air, thus the detection sensitivity is high; and meanwhile, interference substances in the tea are eliminated so as to facilitate the accurate quantitative detection. In addition, the method has low cost, is realized by adopting simple equipment, is simple and convenient and is easy to popularize; and the strict on technical requirements is inferior to that of instrument analysis; and the method is a simple accurate analysis method for detecting pesticide residue of fresh leaves in the production of tea and analyzing the quality of finished tea.

Description

technical field [0001] The invention relates to a method for detecting pesticide residues in tea, in particular to a method for rapid quantitative determination of pesticide residues containing cyanide pyrethroids in tea. Background technique [0002] Pesticide residues in tea not only directly cause harm to the human body through brewing, but also its potential threat and enrichment effect make it a serious social problem. Currently, pyrethroid pesticides are mainly used in tea production and have the most serious residues in tea, most of which are cyanogenic pyrethroids. However, because there is no simple and accurate detection technology for this type of pesticide, it is difficult to obtain real-time monitoring and control in tea production and trade. [0003] The composition of tea is complex and contains a lot of pigments and other interfering substances. The existing methods for the determination of pesticide residues in food cannot be directly used for the detection...

Claims

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Application Information

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IPC IPC(8): G01N21/78G01N1/28
Inventor 张群峰徐胜臻陈玉琼余志倪德江
Owner HUAZHONG AGRI UNIV
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