应用搅拌棒吸附萃取-热脱附-气相色谱-质谱测定烟叶和茶叶中拟除虫菊酯类农药残留

应用搅拌棒吸附萃取(SBSE)技术分别萃取烟叶和茶叶中的5种拟除虫菊酯,并利用热脱附系统将萃取到的物质进行热脱附,然后通过气相色谱-质谱联用仪(GC-MS)进行分析测定。实验过程中对影响SBSE的因素及影响热脱附的条件进行了优化。在优化条件下,采用外标法分别对烟叶和茶叶中的5种拟除虫菊酯类农药残留进行了定量分析。结果表明,烟叶中5种拟除虫菊酯的检出限范围为3.3~11.4 ng,加标回收率为94.8%~103.4%,6次测定的相对标准偏差（RSD）为5.3%~8.6%;茶叶中5种拟除虫菊酯的检出限范围为4.2~10.5 ng,加标回收率为98.2%~110.1%,6次测定的RSD为5.0%~9.6%。实验证明该法具有较高的准确度、灵敏度和较好的重现性,可用于烟叶和茶叶中拟除虫菊酯类农药残留的快速分析测定。

Determination of Pyrethroid Pesticide Residues in Tobacco Leaves and Tea Using Stir Bar Sorptive Extraction-Thermal Desorption and Gas Chromatography-Mass Spectrometry

A novel method for the determination of 5 pyrethroid pesticide residues in tobacco leaf and tea samples was established. The pesticide residues in the samples were extracted and concentrated with stir bar, desorbed by thermal desorption system, and then determined by gas chromatography-mass spectrometry (GC-MS). The pesticide residues in the samples were extracted with a stir bar at 1 100 r/min for 1 h. The desorption was carried out at 300 degrees C for 4 min under a helium flow of 50 mL/min while maintaining a cryofocusing temperature of 0 degrees C in the CIS-4 injector of the GC-MS system. Finally, the CIS-4 injector was raised to a temperature of 300 degrees C and then the analytes were separated by GC and detected by MS. The limits of detection of this method for the tobacco leaves ranged from 3.3 ng to 11.4 ng. The recoveries of pesticides from the tobacco leaves ranged from 94.8% to 103.4% and the relative standard deviations (RSDs) of peak areas ranged from 5.3% to 8.6% (n = 6). The limits of detection of this method for tea ranged from 4.2 ng to 10.5 ng. The recoveries of pesticides from tea ranged from 98.2% to 110.1% and the RSDs of peak areas were less than 9.6% (n = 6). Therefore, this method can satisfy the requirements for the rapid analysis of pesticide residues in the tobacco leaf and tea samples.