Simultaneous determination of five pyrazole fungicides in cereals, vegetables and fruits using liquid chromatography/tandem mass spectrometry

The sensitive analytical method using quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure for simultaneous determination of five novel pyrazole fungicides residues in cereals (rice and wheat), vegetables (cucumber, tomato, and lettuce), and fruits (apple and grape) was developed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The five pyrazole fungicides (bixafen, fluxapyroxad, furametpyr, pyraclostrobin, and rabenzazole) were extracted from seven matrices using acetonitrile and subsequently cleaned up by octadecylsilane (C-18) or graphitized carbon black (GCB) prior to LC-MS/MS analysis. The determination of the target compounds was achieved in less than 3.0 min using an electrospray ionization source in positive mode (ESI+) for furametpyr, pyraclostrobin, and rabenzazole, while negative mode (ESI-) for bixafen and fluxapyroxad. The method showed excellent linearity (at least R-2 >= 0.990) for all studied analytes. The limits of detection were below 3.0 mu g kg(-1), and the limits of quantification did not exceed 9 mu g kg(-1) in all matrices. The overall average recoveries in rice, wheat, cucumber, tomato, lettuce, apple, and grape at three levels (10, 100 and 1000 mu g kg(-1)) were ranged from 70.0% to 108% with all RSDs values less than 20.9% for all analytes. The method is demonstrated to be convenient and reliable for the routine monitoring of pyrazole fungicides in cereals, vegetables and fruits. (C) 2012 Elsevier B.V. All rights reserved.