Determination Method Of Organ Phosphorus Pesticide Residues In Vegetables And It Application

Methods were set up for determination of 11 organ phosphorus pesticides multi-residue in vegetables by gas chromatography and define the scope of application of this method by analysis of vegetable matrix. Vegetable pretreatment method in standard of NY/T 761-2008 was modified in this paper, and DB-17 capillary column and flame photometric detector (FPD) were used. The result showed that 11 organ phosphorus pesticides were separated from each other. The fortified recovery of 11 pesticides gained from cucumber, tomato, and ginger with three spiked levels ranged from71.2% to 117.9%. The Relative standard deviation (RSD) was 2.1% to 11.2%, the Minimum detection limit of the method was 0.005~0.06 mg/kg for DB-17 column, and the Retention time was 6.396 to 19.400 minutes. The calibration curves showed good linearity with correlative coefficient of more than 0.999. Sample was heated up to 40℃when blew by nitrogen (N2), the recoveries of Dichlorovos and Phorate would enhance to 95.00% and 103.3% respectively. Among 13 vegetables detected, green pepper, baby cabbage and shanghai green have several peaks of matrix to impact detection of pesticide residues while garlic chive was found a large number of peaks interfere with the detection of pesticides.A survey of organ phosphorus pesticide in sixty four vegetable samples collected randomly from four supermarkets and one vegetable wholesale market of Guangzhou city was carried out from September to December in 2009. Gas chromatography analysis for 11 organ phosphorus pesticide residues in the samples showed that the qualification rate of leaf vegetables was 71.43%, and no investigated pesticide residue was detected in the all examined the raw melons vegetables, the root vegetables, and the solanaceous fruit vegetables. Five kinds of organ phosphorus pesticides were detected in 10 kinds of samples (64 samples) with the disqualification rate being of 15.63%, among which three prohibited pesticides for planting vegetables according to relevant laws were detected. Forbidden pesticide residue was detected with relatively high frequency in the vegetable samples.The effects of different rinsing methods on the removal ratio of organ phosphorus pesticide residues from Baby cabbage were investigated. The gas chromatography (GC) was used to analyze the pesticide residues in baby cabbage rinsed by different method. The results showed that clear water rinsing, detergent and edible alkali can remove the residual pesticide in baby cabbage at different level, except for treatment with ultrasonic. Among all these methods, detergent with brand of Axe can remove residual pesticide effectively. The removal ratio of Dichlorovos and Dimethoate was 84.38%, 76.11% by detergent with brand of Axe.