A modified extraction and clean-up procedure for the detection and determination of parathion-methyl and chlorpyrifos residues in tea.
Pest Manag Sci
; 57(5): 458-62, 2001 May.
Article
em En
| MEDLINE
| ID: mdl-11374164
ABSTRACT
Recent advances in methodology and instrumentation have made possible the detection and determination of pesticides at microgram 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 from 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.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Chá
/
Resíduos de Praguicidas
/
Cromatografia Gasosa
/
Clorpirifos
/
Inseticidas
/
Metil Paration
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Revista:
Pest Manag Sci
Assunto da revista:
TOXICOLOGIA
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Índia