Effect of Tea Substrate on Quantitative Analysis of Organophosphorus Pesticides by GC Chromatography

Tea and tea soup were used as matrix, the matrix effects of chlorpyrifos, methyl parathion and dichlorvos were analyzed by gas chromatography. The results were as follows:Under the optimized chromatographic conditions, the 3 pesticides had good separation effect and reproducibility. The R² values of standard curves without matrix addition and those with two matrix addition were both greater than 0.99.The ratio of the slope of the standard curve of the same pesticide matrix to that of the standard curve of the pure solvent showed that the enhancement effect of the matrix was obvious. The enhancement effect of matrix on 3 pesticides was dichlorvos > methyl parathion > chlorpyrifos. Matrix had great influence on recovery rate, the recoveries of three standard levels of pesticides in tea were 74.75%~113.20% based on the standard curve of adding substrates, and 80.40%~133.80% based on the standard curve of not adding substrates, when the additive scalar in the tea was 0.4 mg/kg, the recovery rates of the 3 pesticides were all greater than 120%. The RSD value was 0.79%~6.57%, and the matrix had no obvious effect on RSD. It showed that tea had obvious matrix enhancement effect on the low concentration of 3 kinds of pesticide, calibration method using matrix standard curve had good accuracy for the detection of low concentration organophosphorus pesticides.