QuEChERS-液相色谱-串联质谱法测定模拟稻田环境中水、土壤和水稻植株中二氯喹啉酸残留

Determination of quinclorac residue in paddy water,soil and rice plants in a simulated paddy environment based on QuEChERS-liquid chromatography-tandem mass spectrometry

采用液相色谱-串联三重四极杆质谱建立了稻田土壤、稻田水和水稻中二氯喹啉酸残留的检测方法。样品经V(甲酸):V(乙腈)=2:98溶液提取,采用C18和PSA分散固相萃取净化。以0.1%甲酸水溶液-甲醇为流动相梯度洗脱,经反相液相色谱柱实现目标化合物的分离。采用电喷雾正离子模式串联质谱法检测,多反应监测模式定性,外标法定量。结果表明:在0.01~1 mg/L范围内,二氯喹啉酸的质量浓度与对应的峰面积间呈良好线性关系(r≥0.999),方法定量限为0.0125~0.05 mg/kg。当二氯喹啉酸在水稻土壤和植株中的添加水平为0.05、0.2和1 mg/kg,在田水中的添加水平为0.0125、0.05和0.25 mg/kg时,其平均回收率为85%~112%,相对标准偏差(RSD,n=6)为1.1%~9.3%。采用盆栽模拟试验,于水稻苗期喷施二氯喹啉酸,施药剂量为有效成分375 g/hm2,施药后21 d采样测定结果表明:二氯喹啉酸在水稻植株中消解速率较快,消解率可达94%;而在稻田水和土壤中消解缓慢,消解率分别为33%和45%。本研究建立的方法具有操作简单、灵敏度高、分析时间短和重现性好等优点,适用于稻田土壤、稻田水和水稻植株中二氯喹啉酸残留的检测。

A method was established for the determination of quinclorac in paddy soil,paddy water and rice plants by liquid chromatography tandem triple quadrupole mass spectrometry.The sample was extracted with V(formic acid):V(acetonitrile)=2:98.Then the samples were purified by two dispersed solid phase extraction adsorbents of C18 and PSA.With 0.01%(V/V)formic acid-aqueous as the mobile phase gradient elution,the target compound was separated using reversed-phase liquid chromatography column.The samples were detected with positive electrospray ionization(ESI+)in multiple reaction monitoring mode,and quantified by external standard method.The result showed that the linear relationship of quinclorac in the linear range from 0.01 to 1 mg/L was good(r≥0.999).The limit of quantification of quinclorac was 0.0125-0.05 mg/kg.When the spiked levels of quinclorac in soil and plants were 0.05,0.2 and 1 mg/kg,and the spiked levels in field water were 0.0125,0.05 and 0.25 mg/kg,the average recovery rates ranged from 85%to 112%.The relative standard deviations(RSD,n=6)varied from 1.1%to 9.3%.The reliability of the method was verified using a pot experiment.Quinclorac was sprayed onto the rice seedlings at a dose of 375 g/hm2.The results showed that quinclorac was rapidly degraded in rice plants.21 days after application,the dissipation rate of quinclorac was 94%.But the dissipation rates of quinclorac in paddy water and soil were slow.21 days after the treatment,the dissipation rates were only 33%and 45%,respectively.This analytical method is easy to operate,sensitive,fast and stable.It is suitable to detect the quinclorac in paddy soil,paddy water and rice plants.