Study On The Method Of Determination Of Pesticide Residues In Vegetables By GPC-GCMS

With the improvement of peoples’living standards, the question of food safety has attracted more and more attentions. The large-scale use of pesticides, poses a threat to food security as well as improves the production of agricultural products, which also becomes the technical trade barriers in Chinese merchandise exports. This paper takes Chinese chives for example, studied extraction, purification and GC-MS detection conditions of pesticide residues, and developed a new analytical procedure to determine28multiple pesticide residues in vegetables.The experiment results show that the method is simple, fast, few solvent, low cost, automation, environmental protection and reliable. The details are as follows:l.We optimized the chromatogram and MS condition, chose the suitable chromatographic column, temperature programming and selected ions, and then successfully established a GC-MS detection method for the target. The suitable chromatogram and MS condition were that DB-5MS (30m×0.25mm×0.25μm) capillary column and the oven temperature was started at82℃and held for5min; were increased to280℃at a rate of9℃/min, and was held at280℃for15min. In this chromatogram and MS condition,28pesticides were separated well and correlation coefficients were greater than0.999for concentrations from0.005to2.0mg/mL for most pesticides. The limits of detection and the limits of quantification were0.0001～0.0076mg/kg,0.003～0.028mg/kg, respectively.2.Analysis of residues of28pesticides on Chinese chives using QuEChERS sample preparation and gas chromatography-mass spectrometry. Sorbents and solvents were optimized for the cleanup procedure. The determinated QuEChERS sample preparation method was that the sample was extracted with acetonitrile, then was centrifuged for10min, and10mL aliquot extraction solvent was evaporated to dryness before dilution in mobile phase (cyclohexane:acetone (7/3, V/V)) and purified by PSA, then upper layer solvent was injected into the GC-MS system. A majority of the pesticides gave satisfactory recoveries (from70to120%)at0.01,0.05, and0.1mg/kg. The method was proven to be repeatable with RSDs lower than7.66%. The LOD and LOQ ranged from0.05to17.6and0.16to58.8mg/kg, respectively.3.Using the optimized QuEChERS-GPC-GCMS methods,56samples (leek,celety, string beans, purchase from market) were detected, and the determination results shows that the proposed method is rapid, simple, automation, effective and allows the simultaneous analyses of a large number of pesticides with good recoveries, low detection limits, and high throughput.