微波辅助萃取-固相微萃取-气相色谱法同时测定茶叶中的有机氯和拟除虫菊酯农药残留

建立了微波辅助萃取-固相微萃取-气相色谱(MAE-SPME-GC)同时测定茶叶中六六六(α-BHC,β-BHC,γ-BHC,δ-BHC 4种异构体)、滴滴涕类(DDD,DDE,o,p′-DDT,p,p′-DDT)、氯氰菊酯(cypermethrin)和氰戊菊酯(fenvalerate)等10种农药残留的方法。采用外标法定量,除氰戊菊酯外,农药的质量浓度与其色谱峰面积在一定范围内有较好的线性关系,相关系数为0.9705～0.9984。10种组分的加标回收率为64%～121%,相对标准偏差为10.4%～22.9%,检测限为1～50 ng/L。应用该方法测定了市场上3种茶叶中上述农药残留的含量。

Simultaneous Determination of Residues of Organochlorine and Pyrethroid Pesticides in Tea by Microwave Assisted Extraction Solid Phase Microextraction-Gas Chromatography

The issue of residues including organochlorine and pyrethroid pesticides in tea has made a great attention of researchers and customers in the world. Although some analytical methods have well been established to detect these pesticides, the sample preparations are generally laborious, time-consuming, and some of the procedures caused environmental pollution. Solid phase microextraction (SPME) is a novel sample preparation technique since it is of simplicity, high efficiency and solvent free. SPME was firstly developed to address the need to facilitate environment monitoring. In recent years, great efforts have been made in the analysis of pesticide residues in agricultural products by SPME. In this research, a microwave assisted extraction solid phase microextraction-gas chromatography (MAE-SPME-GC) was applied for the simultaneous determination of organochlorine and pyrethroid pesticides, such as benzene hexa chlorides (alpha-BHC, beta-BHC, gamma-BHC and delta-BHC), 1-(2-chlorophenyl)-1-(4-chlorophenyl)-2, 2, 2-trichloroethane (o, p'-DDT), 2, 2-bis (4-chlorophenyl)-1, 1-dichloroethylene (DDE), 2, 2-bis (4-chlorophenyl)-1, 1-dichloroethane (DDD), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1, 1, 1-trichloroethane (p, p'-DDT), cypermethrin and fenvalerate. All the tested pesticides were baseline separated under the experimental conditions, except for DDD and o, p'-DDT. The concentration of each pesticide was calibrated by external standard method. The linearities were found to be in the correlation coefficient range of 0.970 5 to 0.998 4 for the tested pesticides between the mass concentrations and peak areas, except for fenvalerate. The recoveries, relative standard deviations and detection limits for the 10 pesticides were 64% - 121%, 10.4% -22.9%, and 1 - 50 ng/L, respectively. The proposed method was successfully applied to the determination of organochlorine pesticide residues in three kinds of teas from the local market. The experimental results demonstrated that MAE-SPME-GC was a fast, sensitive and green technique for the analysis of trace quantity of pesticides in solid substrate foods.