HPLC Determination of Residual Organonitrogen Pesticides in Tea by Solid-phase Extraction

A methd based on solid-phase extraction (SPE) combined with HPLC for the determination of residual organonitrogen pesticides,namely,metolcarb,propoxur,carbofuran,carbaryl and pirimicarb,in tea was proposed.Pasticides in sample were extracted with solvent mixture of acetone-hexane (vol.ratio 1∶2),purified on a SPE column and eluted with acetonitrile-toluene mixture (vol.ratio 4∶1).HPLC analysis was carried out on a VP-ODS C18 column using a mobile phase of acetonitrile and 60 mmol·L-1 phosphoric acid solution mixture (vol.ratio 40∶60),and detected at 210 nm.At concentration levels between 0.10 and 2.0 mg·kg-1,recoveries of these pesticides were in range of 80.1%-94.8% and RSD′s in the range of 2.21%-7.13%.DL′s were in the range of 0.012 5-0.05 mg·kg-1.