固相萃取-气相色谱法测定茶叶中残留的92种农药

建立了茶叶中92种农药多残留的气相色谱分析方法。茶叶样品用乙腈一次性提取后,有机磷类农药经Envi-Carb固相小柱净化,用10 mL乙腈-甲苯(体积比为3∶1)洗脱剂淋洗,气相色谱-火焰光度检测器(GC-FPD)检测;有机氯类和拟除虫菊酯类农药经串联Envi-Carb和NH2固相小柱净化,用5 mL乙腈-甲苯(体积比为3∶1)洗脱剂淋洗,GC-电子捕获检测器(ECD)检测。采用外标法定量。添加回收试验的结果表明:92种农药的平均回收率为80.3%～117.1%,相对标准偏差为1.5%～9.8%。方法的检出限为0.0025～0.10 mg/kg。该方法的灵敏度、准确度和精密度均符合农药残留测定的技术要求。

Determination of 92 pesticide residues in tea by gas chromatography with solid-phase extraction

A multiresidue analytical method was developed for the determination of ninety-two pesticides in tea using solid-phase extraction (SPE) and gas chromatographic determination. Tea samples were extracted with acetonitrile, organophosphorus pesticides were clean-up by an Envi-Carb SPE cartridge, eluted with 10 mL acetonitrile-toluene (3∶1, v/v) and determined by gas chromatography-flame photometric detection (GC-FPD); organochlorine pesticides and pyrethroids pesticides were cleaned-up by Envi-Carb+NH2 SPE cartridges, eluted with 5 mL acetonitrile-toluene (3∶1, v/v) and determined by gas chromatography-electron capture detection (GC-ECD). The recoveries of those pesticides were ranged from 80.3% to 117.1% by fortification test with the relative standard deviations being from 1.5% to 9.8%. The limits of detection were 0.0025-0.10 mg/kg. The proposed method is characterized by simplicity, higher sensitivity and accuracy.