分散固相萃取-超高效液相色谱-串联质谱法同时测定土壤中新烟碱类农药及其代谢物的残留量

Simultaneous Determination of Residues of Neonicotinoid Pesticides and Their Metabolites in Soil by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry with Disperse Solid Phase Extraction

考虑到采用现有方法提取烯啶虫胺回收率较低,并且缺乏同时检测土壤中新烟碱类农药及其代谢物的方法,开展了题示研究工作。采集离地表20 cm以内的土壤样品,风干、除杂、过筛后分取5 g,加入3.0 mL水,摇匀,静置10 min。加入10 mL含1.0%(体积分数)乙酸的乙腈溶液,振荡30 min,加入5.0 g无水硫酸镁和1.0 g氯化钠,剧烈振荡1 min,于4℃离心5 min。取0.15 g无水硫酸镁、0.05 g N-丙基乙二胺(PSA)置于5 mL具塞离心管中,再加入2.0 mL上述样品提取液,涡旋振荡1 min,于4℃离心3 min。分取0.5 mL上清液,加入0.5 mL水,混匀后过0.2μm滤膜。收集滤液,采用超高效液相色谱-串联质谱仪检测,14种目标物(包括10种新烟碱类农药和4种代谢物)在Waters ACQUITY UPLC HSS T3色谱柱上用不同体积比的含5 mmol·L^(-1)甲酸铵的甲醇溶液和含5 mmol·L^(-1)甲酸铵的0.1%(体积分数)甲酸溶液的混合溶液梯度洗脱分离,用电喷雾离子源正离子(ESI+)模式电离,多反应监测(MRM)模式检测,基质匹配法定量。结果显示:14种目标物的质量浓度分别在2.0~200.0μg·L^(-1)(噻虫胺)和0.5~200.0μg·L^(-1)(其他13种目标物)内和对应的峰面积呈线性关系,检出限(3S/N)为0.36~2.49μg·kg^(-1)。按照标准加入法进行回收试验,回收率为75.4%~112%,测定值的相对标准偏差(n=6)小于9.0%。方法用于16份果园土壤样品的分析,检出了吡虫啉(13份样品)、噻虫嗪(8份样品)和噻虫胺(1份样品),检出量分别为0.007~0.31 mg·kg^(-1),0.005~0.28 mg·kg^(-1)和0.009 mg·kg^(-1)。

Considering the low recovery of nitenpyram using existing methods and lack of methods for simultaneously detecting neonicotinoid pesticides and their metabolites in soil,this study was conducted mentioned by the title.Soil samples were collected within 20cm of the soil surface,dried by air,removed from impurities and sieved.An aliquot(5g)was taken,and mixed with 3.0mL of water.The mixture was shaken,settled for 10min,and mixed with 10mL of acetonitrile solution containing 1.0%(volume fraction)acetic acid.After shaking for 30min,5.0g of anhydrous magnesium sulfate and 1.0g of sodium chloride were added,and the mixture was shaken vigorously for 1min,and centrifuged at 4℃for 5min.Then 0.15g of anhydrous magnesium sulfate and 0.05g of PSA were placed into a 5mL-centrifuge tube with a stopper,and 2.0mL of the above sample extract was added.The mixed solution was shaken for 1min by vortex,and centrifuged at 4℃for 3min.An aliquot(0.5mL)of the supernatant was taken,and mixed with 0.5mL of water.After mixing well,the resulting solution was passed through a 0.2μm filter membrane.The filtrate was collected and detected by the ultra-high performance liquid chromatograph-tandem mass spectrometer.Fourteen targets(including 10 neonicotinoid pesticides and 4 metabolites)were separated on the Waters ACQUITY UPLC HSS T3chromatographic column by gradient elution with mixed solutions composed of methanol solution containing 5 mmol·L^(-1)ammonium formate and 0.1%(volume fraction)formic acid solution containing 5mmol·L^(-1)ammonium formate at different volume ratios,ionized by the ESI+mode,detected by the MRM mode,and quantified by matrix matching method.It was shown that linear relationships between values of the mass concentration and the corresponding peak area of 14targets were kept in the ranges of 2.0-200.0μg·L^(-1)(clothianidin)and 0.5-200.0μg·L^(-1)(other 13targets),with detection limits(3S/N)in the range of 0.36-2.49μg·kg^(-1).Test for recovery was made according to the standard addition method,giving recoveries in the range of 75.4%-112%,and RSDs(n=6)of the determined values were less than 9.0%.The proposed method was applied to the analysis of 16orchard soil samples,and imidacloprid(13samples),thiamethoxam(8samples),and clothianidin(1sample)were detected,with detection amounts of 0.007-0.31mg·kg^(-1),0.005-0.28mg·kg^(-1)and 0.009mg·kg^(-1),respectively.