This work introduces polyurethane (PU) as an efficient and economic sorbent for thin film solid phase microextraction of pyrethroid insecticides, specifically of bifenthrin, fenpropathrin, lambda-cyhalothrin, permethrin, cypermethrin, flucythrinate, fenvalerate and deltamethrin. The PU film is immersed into chrysanthemum tea under ultrasonication for the adsorption of the analytes, and the analytes are desorbed by a mixture of hexane and ethyl acetate and then quantified by gas chromatography with electron capture detection. The film type, adsorption temperature, extraction time, sample condition, and desorption procedure were optimized. The adsorption capacity and robustness of the PU film is found to be excellent for analysis of pyrethroids in chrysanthemum tea. The limits of detection and method limits of detection range from 0.05-0.5 μg L-1 and 0.0003-0.003 μg L-1, respectively. The relative recoveries from spiked samples are between 84.5 and 104.1%, and enrichment factors up to 188. The method was validated through blind split analyses of chrysanthemum tea infusion and ready-to-drink samples with liquid-liquid extraction. Good agreement between the two approaches shows the method to have an accuracy that is similar to that of the conventional technique. Compared with other reported approaches, the PU-based method exhibites a higher sensitivity, easier operation, lower costs and less matrix effects. Graphical abstract Schematic representation of the use of a polyurethane film as an efficient and economic sorbent for the microextraction of 8 pyrethroids by gas chromatography. This method exhibites excellent performance of accuracy, sensitivity, and robustness, demonstrating its potential of application in the analysis of complex matrix.
Keywords: Chrysanthemum tea; Gas chromatography-electron capture detection; Polyurethane sorbent; Pyrethroids; Ultrasound-assisted adsorption.