Graphene Quantum Dots/Eggshell Membrane Composite as a Nano-sorbent for Preconcentration and Determination of Organophosphorus Pesticides by High-Performance Liquid Chromatography

In this study graphene quantum dots/eggshell membrane nanocomposite (GQDS/ESM) is prepared and used as an efficient solid-phase extraction (SPE) sorbent for preconcentration of organophosphorus pesticides (OPPs) from aqueous solutions. The retained analytes on the sorbent are stripped by acetonitrile and subsequently are determined by high-performance liquid chromatography. Various parameters affecting the extraction efficiency of OPPs on the GQDS/ESM, such as solution pH, amount of nano-sorbent, sample loading flow rate, elution conditions and sample volume are investigated. The results demonstrated that the proposed method has a wide dynamic linear range (0.05–100 ng mL^-1), good linearity (R^2 0.997) and low detection limits (0.006- 0.32 ng mL^-1). High enrichment factors are achieved ranging from 110 to 140. In the optimum experimental conditions, the established method is successfully applied for the determination of OPPs in spiked water samples (well, tap, shaft and canal) and apple juice. Satisfactory recovery results show that the sample matrices under consideration do not significantly affect the extraction process.