Fabric phase sorptive extraction followed by HPLC-PDA detection for the monitoring of pirimicarb and fenitrothion pesticide residues.

A sensitive and readily deployable analytical method has been reported for the simultaneous analysis of pirimicarb (PRM) and fenitrothion (FEN) pesticide residues in environmental water samples using fabric phase sorptive extraction (FPSE) followed by high-performance liquid chromatography combined with photodiode array (HPLC-PDA) detector. Both pesticides were successfully determined with a Luna omega C18 column under isocratic elution mode by means of acetonitrile and phosphate buffer (pH 3.0) as the mobile phase. The quantitative data for PRM and FEN were obtained at their maximum wavelengths of 310 nm and 268 nm, respectively. The calibration plots were linear in the range 10.00-750.00 ng mL-1 and 10.00-900.00 ng mL-1 with correlation coefficient of 0.9984 and 0.9992 for PRM and FEN, respectively. Major FPSE experimental variables were investigated in detail, such as contact time with the FPSE membrane, pH and electrolyte concentration, and the volume and type of desorption solvent. Under the optimized conditions, the developed method showed satisfactory reproducibility with relative standard deviations less than 2.5% and low limits of detection of 2.98 and 3.02 ng mL-1 for PRM and FEN, respectively. The combined procedure allows for enhancement factors ranging from 88 to 113, with pre-concentration values of 125 for both analytes. The chromatographic resolutions were approx. 12 for FEN (retention factor of 3.52) and PRM (retention factor of 6.09), respectively, with a selectivity factor of 1.73. Finally, the validated method was successfully applied to real environmental water samples for the determination of these pesticides. Graphical abstract.