Cloud point extraction coupled with Isooctane back extraction for determination of eight pesticide residues in tea beverages by gas chromatography mass spectrometry

Objective: Rapid determination of organochlorine and pyrethroid pesticide residues in tea beverages. Methods: Selecting the non-ionic surfactant PEG-4000 as cloud point extraction, pesticides were extracted with isooctane by ultrasonic back extraction. The upper layer of isoctane solution was analyzed by Gas Chromatography/Mass. The isooctane solution was separated by HP-5 ms UI capillary column and analyzed qualitatively and quantitatively by GC/MS. Results: The eight pesticides showed a good linear relationship between 0.01～2.0 and 0.02～4.0 mg/L, respectively, with the correlation coefficients (R) of over 0.995. The detection limit and quantification limit of this method were 0.003~0.008 mg/L and 0.01~0.02 mg/L, respectively. The average recovery was 78.3%~98.4%, RSD was 2.7%~8.5% (n=6). Conclusion: The method is simple in operation, high in enrichment rate, practical, safe and economical, which is suitable for rapid determination of pesticide residues in tea drinks.