固相萃取-液相色谱质谱法测定稻米中乙虫腈对映体残留

摘要

在3种不同的纤维素手性柱上,对亚砜类手性杀虫剂乙虫腈对映体进行了反相高效液相色谱拆分研究,通过优化手性色谱柱和流动相,实现了乙虫腈对映体基线分离,结合液相色谱-圆二色检测器分析,柱流出顺序为(+)-、(-)-对映体,并在此基础上建立了稻米中乙虫腈对映异构体残留量的高效液相色谱-串联质谱分析方法.稻米样品加水浸润,乙腈高速匀浆、盐析,上清液旋转浓缩后经氨基固相萃取柱净化,洗脱液经氮气吹干后定容.采用纤维素-三(3-氯-4-甲基苯基氨基甲酸酯)(Lux Cellulose-2)手性色谱柱,以甲醇-水(60∶40,V/V)为流动相,液相色谱-串联质谱电喷雾负离子扫描进行分析,外标法定量.以精米和糙米为基质进行3个添加水平和5次重复性实验,结果表明:添加浓度为0.01～0.2 mg/kg,样品中乙虫腈单一对映体平均添加回收率为87.4％～97.8％,相对标准偏差(RSD,n=5)为3.1％～9.3％,方法检出限(LOD)为0.001 mg/kg,定量限(LOQ)为0.003 mg/kg.%A simple and sensitive enantioselective method for the determination of ethiprole enanti-omers in rice was developed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), Ethiprole was enantioseparated with three cellulose-based chiral stationary phases by HPLC-MS/MS. The effects of the mobile phase and column on the enantiosepartion were studied. The direct resolution of ethiprole enantiomers was performed on a cellulose tris (3, 5-dimethylphenyl-carbamate) column (Lux Cellulose-2) using methanol-water (60:40, V/V) as mobile phase, and ( + )-ethiprole and (-)-ethiprole were eluted and determined by a circular dichroism (CD) detector. The ethiprole residues in rice samples were extracted with acetonitrile and cleaned by NH2 column chromatography. HPLC-MS/MS with electrospray in negative ion scan mode was used to determine ethiprole enantiomers. The fortified recoveries of ethiprole enantiomers in rice matrices including polished rice and brown rice were 87.4% 97. 8% at fortification levels ranging from 0. 01 to 0.2 mg/kg. Relative standard deviations were 3. 1% 9. 3%. The limits of quantification for ethiprole enantiomers were both 0. 003 mg/kg.