Methodology for rapid determination of pesticides residues in Cowpea

An ultra performance liquid chromatography tandem mass spectrometric method was established for the simultaneous determining the residues of 9 pesticides in Cowpea.The samples were processed by ultrasonic extraction with acetonitrile.The analysis was detected by UPLC-MS/MS under positive electrospray ionization(ESI+) and multiple reaction monitoring(MRM) mode.The matrixmatched external standard calibration curves were used for the quantitative analysis.Under the optimum conditions,the method showed a good linearity in the range of 0.005～0.50 mg/L with correlation coefficient over 0.99.The limits of quantitation(LOQ) for the pesticide residue were 0.005～0.01 mg/kg.The average recoveries of pesticides residues were 89.0%～110.0% at the spiked levels of 0.01,0.02 mg/kg and 0.10 mg/kg with relative standard deviation(RSDs) of 0.7%～9.1%.The method is sensitive and accurate and is suitable for the simultaneous quantitative determination of 9 pesticides in Cowpea.