气相色谱-串联质谱法测定茶叶中83种农药残留

Determination of 83 Pesticides in Tea by Gas Chromatography Tandem Mass Spectrometry

建立了气相色谱-串联质谱(GC-MS/MS)测定茶叶中83种农药残留的测定方法。茶叶样品经超纯水浸泡,用正己烷提取,过石墨化炭固相萃取小柱净化,待测农药在气相色谱-串联质谱(GC-MS/MS)上测定,用保留时间和特征离子对定性,外标法定量。在最佳的仪器条件下,待测农药在5~500μg/L线性关系良好,定量离子对的相关系数大于0.999,待测农药的检出限LOD(S/N=3)为2~20μg/kg,定量限LOQ(S/N>10)为5~50μg/kg。在空白茶叶样品中添加83种农药,添加水平分别为50、100、500μg/kg时,回收率范围在70.0%~110.0%,相对标准偏差(RSD)范围为3.2%~11.6%。对实际样品检测结果表明,大部分茶叶均有农药残留检出,主要为戊唑醇、溴虫腈、联苯菊酯、氯氟氰菊酯、氯氰菊酯、苯醚甲环唑、溴氰菊酯、唑虫酰胺,检出浓度集中在10~1000μg/kg。该方法不但可以有效降低基线,减少杂峰的干扰,而且简单、灵敏、稳定,方法灵敏度满足国内外农药残留监测限量标准要求。

A method for the determination of 83 pesticide residues in tea by gas chromatography tandem mass spectrometry(GC-MS/MS)was developed.Tea samples were soaked in ultrapure water,extracted with n-hexane and purified by graphitized carbon solid phase extraction columns.The pesticides in the extracts were determined by GC-MS/MS,qualitative analysis was based on retention time and characteristic ion pair,and quantitative analysis was based on external standard method.Under the optimum instrument conditions,linear regression was established for pesticides in the range of 5-500μg/L.The correlation coefficient of quantitative ion pair was greater than 0.999,and the detection limit(S/N=3)of pesticides was 2-20μg/kg,quantification limit(S/N>10)was 5-50μg/kg.83 pesticides were added to the blank tea samples at the spiking levels of 50,100,and 500μg/kg,and the recovery was in the range of 70.0%-110.0%,with a relative standard deviation of 3.2%-11.6%.This method can not only effectively reduce the baseline and reduce the interference of miscellaneous peaks,but is also simple,sensitive and stable.The sensitivity of the method meets the requirements of pesticide residue monitoring limit standards.The established method was used to detect the imported and exported tea.The results showed that most tea leaves had pesticide residues,mainly including tebuconazole,chlorfenapyr,bifenthrin,cyhalothrin,cypermethrin,difenoconazole,deltamethrin and tolfenpyrad.The detected concentration was in 10-1000μg/kg.Therefore,it is necessary to establish the analytical method of agricultural residues in tea to ensure the food safety.