Simple one-step preconcentration and cleanup with a micellar system for high performance liquid chromatography determination of pyrethroids in traditional Chinese medicine
A novel but simple one-step preconcentration and cleanup using a micellar system was developed to extract and preconcentrate four pyrethroids including beta-cyfluthrin, cyhalothrin, cyphenothrin and permethrin in traditional Chinese medicine with the use of the non-ionic surfactant Triton™ X-114. Before the high performance liquid chromatography analysis, a cleanup stage by adding an appropriate sorbent to remove the interfering components from the extracts was optimized. Based on results from the analysis, the best recoveries (86.8% to 94.3%) were obtained by preconcentration with 15% (m/v) sodium chloride, 2 : 1 (g g−1) of activated carbon/sample, and equilibration at 60 °C for 40 min, which was after a micellar extraction with 7.0% (v/v) Triton™ X-114, liquid : solid ratio of 20 : 1 (mL g−1), and an ultrasonic extraction time of 20 min at pH 7.0. The results of the four pyrethroids were linear within the range of 0.06–6.00 μg g−1. The limits of detection of beta-cyfluthrin, cyhalothrin, cyphenothrin and permethrin were 0.0108, 0.0086, 0.0083 and 0.0092 μg g−1, respectively. Consequentially the method was applied for the extraction and determination of the four pyrethroids in different traditional Chinese medicines (Rhubarb, Herba lysimachiae, Ardisia japonica and the fruit of Camptotheca acuminata). Based on these results, the proposed method was a simple, effective and environmental friendly technique for the analysis of pyrethroid residues.