棉花中7种烟碱类农药残留的液相色谱-串联质谱法测定

Determination of seven neonicotinoids pesticide residues in cotton samples by using high performance liquid chromatography tandem mass spectrometry

应用液相色谱一电喷雾电离三级四极杆串联质谱（LC-ESI-MS／MS）仪器，建立测定棉花中7种烟碱类农药残留的检测方法。样品先添加同位素内标吡虫啉-D4，再用乙腈超声提取、浓缩，乙腈-甲酸（0．15％）溶液溶解，以ZORBAX Eclipse XDB-C。色谱柱为分离柱。液相色谱-串联质谱仪采用正离子扫描方式，多反应监测，每种烟碱类农药各选2对离子进行定性、定量分析，除吡虫啉外均采用外标法定量。在0～12．5μg／L测定范围内此方法具有良好的线性关系（r〉0．99），在10、20和40μg／kg3个水平进行添加回收实验，平均回收率范围为75．9％～98．4％；相对标准偏差小于15．8％；方法检测低限（LOQ）均为10μg／kg。

A high performance liquid chromatography tandem mass spectrometry（LC-ESI-MS/MS） was established for determination of 7 classes of neonicotinoid pesticides in cotton samples. The isotope internal standard （imidcacloprid-D4） was added into the sample, and then it was ultrasonic extracted with acetonitrile. The extracted solution was dried with a rotavapor, redissolved in the solvents of acetonitrile and 0.15% formic acid. It was analyzed by LC-MS/MS in positive mode with multiple reaction monitoring, and ZORBAX Eclipse XDB-Cs column as the separation column. The one precursor/ two product ion transitions for each of the neonicotinoids were used. The method was quantified by external standard method except imidaeloprid. The results show that the working curves were linear in the range of 0 - 12.5 μg/L （ r 〉 O. 99）. The recoveries were between 75.9% - 98.4% and the relative standard deviations were less 15.8% at the spiked levels of 10, 20 and 40 μg/kg. The limits of quantitation were 10 μg/kg.