In this work, a new rapid method for the determination of 135 pesticide residues in green and black dry tea leaves and stalks employing gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) with a triple quadrupole was developed and validated. A substantial simplification of sample processing prior to the quantification step was achieved: after addition of water to a homogenised sample, transfer of analytes into an acetonitrile layer was aided by the addition of inorganic salts. Bulk co-extracts, contained in the crude organic extract obtained by partition, were subsequently removed by liquid-liquid extraction using hexane with the assistance of added 20% (w/w) aqueous NaCl solution. The importance of matrix hydration prior to the extraction for achieving good recoveries was demonstrated on tea samples with incurred pesticide residues. For most of the analytes, recoveries in the acceptable range of 70-120% and repeatabilities (relative standard deviations, RSDs) ≤20% were achieved for both matrices at spiking levels of 0.01, 0.1 and 1mgkg-1. Under optimised GC-MS/MS conditions, most of the analytes gave lowest calibration level ≤0.01mgkg-1, permitting the control at the maximum residue levels (MRLs) laid down in Regulation (EC) No 396/2005. The developed method was successfully applied to the determination of pesticide residues in real tea samples.
|Original language||English (US)|
|Number of pages||10|
|Journal||Analytica Chimica Acta|
|State||Published - Sep 19 2012|
Bibliographical noteFunding Information:
The financial support of the Ministry of Education, Youth and Sports of the Czech Republic (projects MSM 6046137305 , MSMT No. 21/2012 and AMVIS LH11059 ) is acknowledged.
Copyright 2013 Elsevier B.V., All rights reserved.
- Gas chromatography (GC)
- Pesticide residues
- Sample preparation
- Tandem mass spectrometry (MS/MS)