High-performance liquid chromatography-tandem quadrupole-time of flight-mass spectrometry for determination of 29 pesticides in litchi.

An analytical method was established for the simultaneous determination of 29 pesticides in litchi by a high-performance liquid chromatography-tandem quadrupole-time of flight-mass spectrometry (HPLC-Q-TOF/MS) technique combined with an optimized QuEChERS procedure. The samples were extracted by acetonitrile and the acetonitrile supernatant was collected for purification after salting-out (magnesium sulfate anhydrous and sodium chloride) and centrifugation.Under the optimized chromatographic and mass spectrometric conditions, the data were collected by electrospray ionization (ESI) sources in positive and negative ion modes. The calibration curves of 29 pesticides showed good linearity in a concentration range of 0.001-0.2 mg/L (R²>0.99). The average recoveries were 70.2%-102.4% at three spiked levels (0.01, 0.1, 0.50 mg/kg), while the relative standard deviations (RSD) were 2.4%-6.2%. The limits of detection and limits of quantification ranged from 0.1 μg/kg to 3 μg/kg and 0.3 μg/kg to 10 μg/kg, respectively. This method was a simple and efficient method with high sensitivity and precision and had practical value for the rapid detection of residues of 29 pesticides in litchi. [ABSTRACT FROM AUTHOR]