A sol-gel technique bases on Ionic liquid/chitosan-reinforced hollow fibre-stir bar sorptive micro extraction followed by gas chromatography-flame ionization detector for the determination of five organophosphorous pesticides in rat liver and rice samples using response surface methodology

Organophosphorus pesticides (OPPs) are applied extensively throughout the world due to their wide activity against pests and relatively low cost [1]. Therefore selective and sensitive determination of OPPs is of increasing interests [2]. In this study, a sensitive, rapid and reproducible solid phase microextraction configuration combining the principles of sol-gel technique [3], hollow fiber solid phase microextraction and stir bar sorptive micro extraction [4] followed by gas chromatography-flame ionization detector was developed and validated for the determination of five OPPs in rat liver and rice samples. The main feature of this method is reinforcing the microporouses of hollow fiber with ionic liquid and chitosan microspheres on the basis of sol-gel process. Ionic liquid and dispersed chitosan sorbents act as the acceptor (liquid/solid) phase for the collection and extraction of target analytes, thus affording extraction process like SBSE, while a thin stainless steel wire in the lumen of hollow fiber acts as the magnetic stirrer. Several Parameters affecting extraction efficiency have been investigated and optimized for the proposed method using response surface methodology (central composite design). Under the optimized extraction conditions, the enrichment factors were achieved in the range from 289 to 311 with good inter-fiber repeatability and fiber-to-fiber reproducibility, while good linearity (0.985-0.992) and recovery (76-85%) were obtained. The newly developed method has limits of detection for each OPP from 0.002 to 0.008 mg L-1 with intra-day and inter-day precision ranging from 3.2% to 5.6% and from 4.3% to 5.7%, respectively. The proposed method was successfully applied to the rice and rat liver samples spiked with OPPs, demonstrating its rare application in food safety analysis and biological sample monitoring.