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

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。

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

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.