QuEChERS-GC/MS Analysis of the Residues of Chlorpyrifos Degraded by Bacillus subtilis on the Phyllosphere of Brassica chinensis
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Abstract:
In China, chlorpyrifos, as one of the most suitable pesticides to replace the highly toxic organophosphorus pesticides, has been widely used to control pests and diseases in vegetable production. However, the food safety problems brought by chlorpyrifos have attracted more and more attention. Therefore, it is very important to establish new methods for rapid detection of chlorpyrifos residues. In this study, an improved method, QuEChERS sample pretreatment coupled to gas chromatography-mass spectrometry (GC-MS) has been developed for rapid detection of the residual amount of chlorpyrifos on the phyllosphere of Brassica chinensis. The sample was extracted with acetonitrile containing 1% acetic acid, and purified with an appropriate amount of N-propyl Ethylenediamine(PSA), anhydrous magnesium sulfate, graphitized carbon black(GCB) and C18 filler, before analysis by gas chromatography-mass spectrometry and quantification with external standards. The obtained results showed a good linear relationship in the concentration range of 0.20~1.00 mg/L with correlation coefficients greater than 0.999. When the spiked level was 0.10~0.50 mg/kg, the average recoveries of chlorpryrifos were 72.00%~111.00%, with the relative standard deviations as 1.30%~1.60%, limit of detection (LOD) as 0.005 mg/kg, and limit of quantitation (LOQ) as 0.01 mg/kg. The established method is simple, rapid, accurate and sensitive, and can meet the requirements for qualitative and quantitative analysis of the residues of chlorpyrifos on the phyllosphere of Brassica chinensis. Bacillus subtilis 3374 could degrade effectively the chlorpyrifos residues on the phyllosphere of Chinese cabbage.
