分散固相萃取-分散液液微萃取结合气相色谱-三重四极杆质谱法测定茶叶中7种拟除虫菊酯类农药残留

摘要

A gas chromatography-triple quadrupole mass spectrometric (GC-MS/MS) method forthe determination of 7 pyrethroid pesticide residues in tea was developed using dispersive solid-phase extraction and dispersive liquid-liquid microextraction (d-SPE-DLLME) as sample preparation methods.The samples were extracted with acetonitrile,purified with primary secondary amine (PSA) and multi-walled carbon nanotubes (MWCNTs) as sorbents,concentrated into carbon tetrachloride (CCl4),and analyzed by GC-MS/MS.The effects of different kinds of extractants,volume and types of extractants,volume of dispersants and extraction time on extraction efficiency were investigated by using full fermented black tea as the matrix.In the experiment,acetonitrile was used as extractant in d-SPE,200 μL of CCl4 was used as extractant,1 mL of acetonitrile was used as dispersant,and extraction time was 1 min in DLLME.The results showed that the calibration curves of 7 pesticides were linear in the range of 10-500 μg/kg,and the limits of quantitation were 1.0-10.0 μg/kg.The average recoveries of 7 pesticides in four kinds of tea(black tea,green tea,oolong tea and dark tea)at four spiked levels were in the range of 75.4％-113.6％.The relative standard deviations(RSD,n =5) were not more than 8.8％.The proposed method showed the advantages of simplicity,rapidness,low cost and low detection limit,and was successfully applied in the detection of twelve commercially available tea samples.%将分散固相萃取和分散液液微萃取(d-SPE-DLLME)相结合,并与气相色谱-三重四极杆质谱(GC-MS/MS)联用,建立了快速测定茶叶中7种拟除虫菊酯类农药残留的方法.样品经乙腈提取,N-丙基乙二胺(PSA)和多壁碳纳米管(MWCNTs)净化,四氯化碳(CCl4)浓缩萃取后,采用GC-MS/MS进行分析.以全发酵红茶为基质,考察了提取剂种类、萃取剂的种类和体积、分散剂体积以及萃取时间对萃取效率的影响.以乙腈为提取剂进行分散固相萃取,在进行分散液液微萃取时,以200 μL CCl4为萃取剂,1 mL乙腈为分散剂,萃取时间为1 min.结果表明,7种拟除虫菊酯类农药在10 ～500 μg/kg浓度范围内线性关系良好,定量下限为1.0 ～ 10.0 μg/kg.7种农药在4种茶叶(红茶、绿茶、乌龙茶和黑茶)中4个添加水平下的平均回收率为75.4％ ～113.6％,相对标准偏差(RSD,n=5)不大于8.8％.该方法具有简单、快速、成本低、检出限低的特点.应用所建立的方法对12种市售茶叶样品进行检测,结果满意.