期刊
PEST MANAGEMENT SCIENCE
卷 57, 期 5, 页码 458-462出版社
JOHN WILEY & SONS LTD
DOI: 10.1002/ps.312
关键词
residue analysis; parathion-methyl; chlorpyrifos; tea; caffeine
Recent advances in methodology and instrumentation have made possible the detection and determination of pesticides at mug kg(-1) (ppb) levels. The sensitivity of a method of analysis depends greatly on the efficient extraction of the pesticide and the subsequent clean-up of the extract. The extract from green tea leaves is a mixture of aroma components, polyphenols and caffeine. The preparation of made tea fi om green tea leaves adds to this complexity by concentrating these coextractives. Conventional clean-up techniques provide poor recoveries for parathion-methyl and chlorpyrifos from both green tea leaves and made tea. This arises from interference by caffeine during gas chromatography, as it has a similar retention time to the two pesticides and peaks overlap. A modification to the protocol based on a solvent partitioning process using dichloromethane and subsequent washing of the extracts with warm water removed the caffeine, and pigments were removed by column chromatography. Recoveries ranging from 80 to 90% were then obtained for both pesticides. (C) 2001 Society of Chemical Industry.
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