Abstract
A method based on direct immersion solid‐phase microextraction (DI‐SPME) coupled with high performance liquid chromatography combined with post‐column photochemically induced fluorimetry derivatization and fluorescence detection (HPLC‐PIF‐FD) was developed to extract three pyrethroid insecticides, i.e. cyfluthrin, cypermethrin, and flumethrin from water samples. A sol‐gel based coating fiber using 3‐(trimethoxysilyl propyl) amine as precursor was prepared and used for the extraction of the pyrethroids from groundwater samples. A post‐column photochemical reactor was designed and constructed for the derivatization of these environmentally important pollutants to increase their fluorescence sensitivity and determination in HPLC. The parameters affecting extraction process (extraction time and temperature, pH, salt addition, and co‐solvent) and desorption step (solvent, desorption time, and temperature) of the analytes from the sol‐gel‐based fiber, along with photochemical reaction conditions were investigated. The developed method proved to be relatively rapid, simple, and easy and offers high sensitivity and reproducibility. Linear dynamic ranges (LDR) for these insecticides were ranged between 0.25 to 50 μg/L. The regression coefficients were satisfactory (R^2^ > 0.984) for these pyrethroids. The limits of detection and limits of quantification varied between 0.09 and 0.35 μg/L and 0.25 and 1.00 μg/L, respectively. Relative standard deviation RSDs values varied between 4.41% and 6.20%. Relative recoveries obtained from analysis of Jajroud river water sample ranged between 94% and 104%.