茶基质对气相色谱法定量分析有机磷农药的影响

选用茶叶、茶汤为基质,气相色谱法分析茶叶、茶汤对毒死蜱、甲基对硫磷、敌敌畏的基质效应。结果表明:优化色谱条件下,3种农药有较好分离效果和重现性。以不添加基质标准曲线与分别添加2种基质标准曲线的R2值均大于0.99;同一种农药基质标准曲线斜率与纯溶剂标准曲线斜率之比得出,基质增强效应明显,茶叶茶汤对3种农药的基质效应为敌敌畏 > 甲基对硫磷 > 毒死蜱。基质对回收率有较大影响,以添加基质的标准曲线定量,3种农药3个加标水平的回收率为74.75%~113.20%;以不添加基质的标准曲线定量,3种农药3个加标水平的回收率为80.40%~133.80%,其中茶叶3种农药加标量为0.4 mg/kg时,3种农药的回收率均超过120%。RSD(相对标准偏差)在0.79%~6.57%之间,基质对RSD影响不明显。说明茶基质对低浓度3种农药具有明显基质增强效应,采用基质标准溶液的定量方式对低浓度水平有机磷农药的检测有较好准确度。

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.