[Analysis of 112 pesticide residues in vegetables using dispersive-solid phase extraction and gas...

A method was developed and validated for the simultaneous analysis of 112 pesticide residues in vegetables by gas chromatography coupled with triple quadrupole mass spectrometry (GC-QQQ-MS/MS). It is demonstrated that the optimized conditions could provide a more accurate quantitation and lower limit of quantification of the analysis by dispersive-solid phase extraction (D-SPE) cleanup. The samples were extracted with acetonitrile and toluene (8: 1, v/v), and cleaned up by D-SPE. To every 5 mL extraction solution, 0.8 g MgSO4, 0.05 g graphitized carbon black (GCB), 0.1 g ethylenediamine-N-propyl silyl (PSA) and 0.05 g C18 were added. The extracts were analyzed by GC-QQQ-MS/MS using internal standard method. The recoveries of the 112 pesticides at three spiked levels of 20, 50 and 200 microg/kg were ranged from 53.1% to 138.7%, and among which those of 86 pesticides were from 65.0% to 120.0%. The relative standard deviations (RSD) were less than 12%. The limits of quantifications (LOQs) (signal/noise at 10) were between 1.6 and 13.4 microg/kg. The vegetable samples collected from the market such as garlic chives, cucumber and purple cabbage were analyzed, and the residues of triazophos and fenpropathrin were detected in some of these samples. The method can be applied to the routine analysis for the determination of the 112 pesticides in vegetable samples.