Solid-phase microextraction with a novel graphene-coated fiber coupled with high-performance liquid chromatography for the determination of some carbamates in water samples

In this study, a novel graphene nanocomposite was synthesized and used as a solid-phase microextraction fiber coating material. The application of the graphene-coated fiber was evaluated through the extraction and determination of the four carbamate pesticides (carbofuran, carbaryl, pirimicarb, diethofencarb) in water samples by high performance liquid chromatography-diode array detection. Parameters that affect the extraction efficiencies, such as the extraction time, stirring rate, extraction temperature, and salt addition, were investigated and optimized. Compared with the two commonly used commercial fibers (CW/TPR, 50 mu m; PDMS/DVB, 60 mu m), the graphene-coated fiber showed higher extraction efficiency. Under the optimum conditions, the limits of detection (LODs), based on a signal-to-noise ratio (S/N) of 3, were 0.1-0.8 ng mL(-1). The limits of quantification (LOQ, S/N 9) were 0.3-2.4 ng mL(-1). The linearity was observed in the range from their corresponding LOQs to 400.0 ng mL(-1) with the correlation coefficients (r) ranging from 0.9994 to 0.9998. The recoveries of the carbamate pesticides from water samples at spiking levels of 10.0, 50.0 and 100 ng mL(-1) were in the range of 83.8%-95.4%, and the relative standard deviations were between 2.2% and 6.6%.