Development of Simple Sample Pretreatment Method for the Simultaneous Analysis of Organochlorine and Pyrethroid Pesticide Residues in Tea
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Abstract:
Eleven types of organochlorine and pyrethroid pesticides in tea samples were analyzed simultaneously and rapidly in this study. Using a simple pretreatment method, the tea samples were fully ground with the adsorbent, and then the matrix was purified by column chromatography followed by detection using gas chromatography (GC). Adsorbent, column, and eluent conditions were investigated, and the optimized conditions were as follows: 1.0 g of sample immersed in water was combined completely with 4.0 g of neutral aluminum oxide, and the mixture was transferred into a self-made glass column containing 2.0 g of anhydrous sodium sulfate, 2.0 g of Florisil, and 0.1 g of activated carbon for purification and pre-separation. The combined sample was then eluted with 20 mL of ethyl acetate and n-hexane (2:3, V:V). For this method, the linear range of the calibration curves was between 0.1 mg/L and 2.0 mg/L, the coefficients of determination were ≥0.9962 for all target analytes except cyfluthrin and cypermethrin, and the limit of detection ranged from 0.0000321 ng to 0.1451379 ng. The recoveries ranged from 68.44% to 119.20%, and the relative standard deviations of the recovery results at different spiking levels were lower than 14.73%. In addition, the matrix effect (ME) issue in the tea sample was investigated in detail, and the method of matrix-matched calibration was applied to solve the ME issue effectively. This developed method is fast, accurate, simple, and environmentally friendly, and is suitable for the simultaneous and rapid separation and analysis of various pesticide residues in tea.
