Abstract

A novel porous sheet microextraction method was developed using waste polystyrene foam (WPSF) composited with polypyrrole (PPy) for the extraction of four organophosphate pesticides (OPPs) including dimethoate, dichlorvos, malathion, and chlorpyrifos from fruits and vegetables. The samples were then analyzed using high-performance liquid chromatography with diode array detection (HPLC-DAD). The fabricated porous sheet absorbent is simple to prepare, inexpensive, highly efficient in extraction, and utilizes waste material as a sorbent. Scanning electron microscopy (SEM) revealed that the hybrid WPSF and PPy in porous sheet microextraction exhibited a uniform distribution of PPy on the WPSF sheet, resulting in a structure with small porosity and large surface area. Under optimal conditions, good linearities achieved from 24.0 ng mL⁻¹ to 3.2 μg mL⁻¹ for dimethoate, 13.8 ng mL⁻¹ to 3.2 μg mL⁻¹ for dichlorvos, 49.3 ng mL⁻¹ to 8.0 μg mL⁻¹ for malathion, and 6.9 ng mL⁻¹ to 3.2 μg mL⁻¹ for chlorpyrifos. The limits of detection (LODs) and quantification (LOQs) were obtained from 2.1 to 14.8 ng mL⁻¹ and 6.9 to 49.3 ng mL⁻¹, respectively. The method demonstrated good precision (n = 6, %RSD=1.73–4.96 %) and reproducibility between different sorbents (%RSD=1.64–6.18 %). Additionally, the hybrid WPSF and PPy in porous sheet sorbent could be reused for up to 10 cycles with an extraction efficiency above 90 %. This hybrid WPSF and PPy in porous sheet microextraction was successfully applied to extract dimethoate, dichlorvos, malathion, and chlorpyrifos from fruit and vegetable samples, with good recoveries ranging from 81.8 ± 1.9 % to 104.5 ± 1.8 %.