Journal
ANALYTICA CHIMICA ACTA
Volume 743, Issue -, Pages 51-60Publisher
ELSEVIER
DOI: 10.1016/j.aca.2012.06.051
Keywords
Tea; Pesticide residues; Sample preparation; Gas chromatography (GC); Tandem mass spectrometry (MS/MS)
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Funding
- Ministry of Education, Youth and Sports of the Czech Republic [MSM 6046137305, 21/2012, AMVIS LH11059]
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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 1 mg kg(-1). Under optimised GC-MS/MS conditions, most of the analytes gave lowest calibration level <= 0.01 mg kg(-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. (C) 2012 Elsevier B.V. All rights reserved.
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