Screening and confirmation of pesticide residues in substitutional tea such as orange peel, lotus leaf, pueraria lobata and Pangdahai

Abstract

The screening method was established for pesticide residues in substitutional teas such as orange peel, lotus leaf, pueraria lobata and Pangdahai using data base. The method for analyzing of 26 pesticide residues was confirmed in four substitutional teas with gas chromatography-tandem mass spectrometry(GC-MS/MS) and dispersive solid-phase extraction(d-SPE) for sample preparation. The 26 types of pesticides were selected as target compounds, including screened out, commonly used in substitutional tea planting and forbidden in agriculture planting. The samples extracted with acetonitrile, and purified by adsorbent(e. g PSA, GCB, C_(18)), the purification solutions were separated on DB-5 MS UI column((15 m+PUU+15 m)×0. 25 mm×0. 25 μm) with programmed temperature and determined by GC-MS/MS in multi-reaction monitoring(MRM) model. The external standard method was applied to quantify the pesticides. The method showed a good linearity(r≥0. 995)in concentration range(2-100 μg/L) for 26 kinds of pesticides. The limits of quantification(LOQ) were 3-40 μg/kg. The average recoveries range were 71. 9%-114. 4% in three add levels of 10, 50, 200 μg/kg, and relative standard deviations of 1. 0%-16. 0%(n=6). In the four matrixes, the pesticides were detected concentrating on orange peel, and there were kinds of residues. This method is simple, fast, sensitive, selective and can satisfy the request of pesticide screening and simultaneous analysis of multiple pesticide residues in orange peel, lotus leaf, pueraria lobata and Pangdahai.