A high-performance liquid chromatography-tandem mass spectrometric (HPLC-MS/MS) method was developed to analyze abamectin in sediment.The sample was extracted with a mixture of hexane and acetone by ultrasound-assisted microwave extraction,and purified with solid phase extraction column packed with primary/secondary amine and graphite carbon black.The analytes were separated on a Thermo-C18 column(50 mm ×2.1 mm,1.9 μm) using a mixture of acetonitrile ∶ acetic acid-ammonium acetate ∶ water(75 ∶ 10 ∶ 15) as mobile phase.The analysis of the target compounds was performed under atmospheric pressure chemical ionization mode with multiple reaction monitoring.The quantification of abamectin was based on internal standard calibration(emamectin benzoate as the internal standard),and the calibration standards were prepared using matrix-matched solution for compensation of matrix effect.The calibration curve of abamectin was linear in the range of 1.6-400 μg/L with correlation coefficient(r2) of 0.999 3.The relative standard deviations ranged from 2.2％ to 16.2％,and the limit of detection was 0.18 ng/g by dry weight.The established method was used to analyze sediment samples collected from an urban stream in Guangzhou,and the results were compared with those obtained by the HPLC/fluorescence detection after derivatization.Similar results were achieved by both methods,but the HPLC-MS/MS method showed greater sensitivity and simplicity,and was suitable for the detection of sediment-associated abamectin at low concentrations.%建立了水体沉积物中阿维菌素残留的高效液相色谱-串联质谱(HPLC-MS/MS)检测方法.沉积物样品采用超声微波萃取、固相萃取净化.待测物通过Thermo-C18色谱柱(50 mm×2.1 mm,1.9 μm)分离,乙腈∶乙酸-乙酸铵缓冲液∶水混合溶液(75∶10∶15,体积比)为流动相洗脱,大气压化学电离-多反应负离子监测模式检测,内标法定量.通过加入内标物甲氨基阿维菌素苯甲基盐并采用基质加标标准曲线进行校正.研究表明,阿维菌素的线性范围为1.6～400μg/L,相关系数(r2)达到0.9993.不同浓度加标样品的相对标准偏差(n=3)为2.2％～16.2％,方法的检出限为0.18 ng/g(干重).野外样品检测显示,HPLC-MS/MS方法与衍生化-液相色谱/荧光检测法的分析结果相当,但前者更灵敏、简便,适用于沉积物中痕量阿维菌素残留的测定.
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