Method for determining residues of chlorothalonil, captan, captafol and folpet in vegetables and fruits

Abstract

The invention relates to a method for determining the residues of chlorothalonil, captan, captafol and folpet in vegetables and fruits. The method specifically includes the steps of: preparing a sample; treating the sample with phosphoric acid; extracting a target object with acetonitrile; removing the phosphoric acid and water soluble impurities from the extracted solution; conducting further purification with a Florisil small column and aminopropyl powder; and carrying out detection by an Agilent7890A gas chromatograph-electron capture detector. The determination method employs 5% phosphoric acid to treat a fruit and vegetable sample, thus avoiding loss of the four pesticides during sample crushing. The method is suitable for determining the four pesticide residues in all vegetables and fruits, has recovery rates all over 80%, and can make determination of the four pesticide residues in vegetables and fruits more accurate and reliable.

Description

technical field [0001] The invention relates to the technical field of detection and application of pesticide residues, in particular to the determination of chlorothalonil, captan, captafol and folpet pesticide residues in vegetables and fruits. Background technique [0002] Chlorothalonil is a non-systemic substituted benzene broad-spectrum fungicide. Captan, folpet and captafol are a class of multi-action point phthalimide broad-spectrum protective fungicides. These four fungicides have good killing effects on fungal diseases of various crops, are less harmful, and have preventive effects, and are widely used in crops such as fruits and vegetables. Foreign developed countries have clearly defined the maximum residue limits of these pesticides in fruits and vegetables. For example, Japan’s positive list stipulates that captafol in vegetables and fruits cannot be detected, and the maximum residue limits (MRL) of chlorothalonil in radish and apple are respectively 0.1mg / kg ...

AI Technical Summary

Problems solved by technology

These four pesticides are unstable in an alkaline environment, and the recovery rate of addition in some vegetables and fruits is lower than 35%. Most of the existing literature detection methods and standard methods do not involve the instability of these four pesticides in an alkaline environment. Some documents and standard methods add phosphoric acid or ZnAc solution to improve the stability of captan, folpet, captafol and chlorothalonil after the sample is crushed and before extraction. Some samples will degrade when broken, so as a positive sample, the sample is broken directly during sample preparation, even if phosphoric acid is added before extraction to change the pH value of the extraction environment, accurate and reliable quantitative results cannot be obtained

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