气相色谱/质谱选择离子检测法同时测定大米中的25种持久性有机污染物

Simultaneous Determination of 25 Persistent Organic Pollutants in Rice by Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring Mode

利用超声波提取、固相萃取净化对样品进行前处理,然后采用气相色谱/质谱选择离子检测模式对大米中的25种持久性有机污染物进行了分析。色谱条件:DB35MS毛细管色谱柱(30m×0.25mmi.d.×0.25μm);载气为氦气,流速1mL/min;进样口温度300℃;不分流进样,进样量1μL;柱温为程序升温模式。质谱条件:电子轰击电离源,70eV;采集方式为选择离子方式,扫描质量范围50～450u。实验采用保留时间以及定性、定量特征离子的丰度比定性,采用峰面积外标法定量,制作了25种持久性有机污染物的标准工作曲线。不同浓度水平的添加回收率试验表明,25种持久性有机污染物的添加回收率为81.99%～100.60%,相对标准偏差为2.37%～18.48%,除异狄氏剂、反式氯丹和顺式氯丹的检测限分别为20,30和20ng/g外,其他有机污染物的检测限为0.1～5ng/g。该方法的灵敏度、准确度和精密度均符合农药多残留测定技术的要求。

A multi-residue analytical method for the simultaneous determination of persistent organic pollutants (POPs) in rice samples was developed. POPs were extracted from rice with ethyl acetate/n-hexane(80∶20,v/v) by sonication, and determined by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode. A fused silica capillary column DB-35MS (30 m× 0.25 mm i.d. ×0.25 μm) was employed. Operating conditions were as follows: injector port temperature, 300 °C; column temperature, programming; carrier gas, helium; flow rate, 1.0 mL/min; sample size, 1 μL with splitless injection. The mass spectrometric detector (MSD) was operated in electron impact ionization mode with an ionizing energy of 70 eV. Analysis was performed with selected ion monitoring (SIM) using one target and one or two qualifier ion.POPs were confirmed by their retention times, their qualifier and target ions, and their qualifier/target abundance ratios. Recovery studies were performed at 0.05, 0.1, and 0.5 mg/L spiked levels of each POPs, and the recoveries obtained ranged from 81.99% to 100.60% with relative standard deviations between 2.37% and 18.48%. The detection limits of the method ranged from 0.1 to 5 ng/g for the different POPs except endrin, trans-chlordane and cis-chlordane. The results show that the method developed is sensitive and reliable.