[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.