A Graphene Oxide-Based Composite for Solid-Phase Extraction of Carbamate Pesticides from Vegetables

In this work, a graphene oxide-based composite (DABP-GO) was prepared by aminating graphene oxide (GO) with the diazonium salt of 4,4 '-diaminobiphenyl (DABP). The DABP-GO composite was characterized by scanning electron microscopy, infrared spectroscopy, and nitrogen adsorption-desorption. The DABP-GO showed to be an effective solid-phase extraction (SPE) adsorbent for carbamate pesticides. A SPE method with the DABP-GO as the adsorbent combined with high-performance liquid chromatography with ultraviolet detection was established to determine trace carbamate residues in vegetable samples (benincasahispida and pakchoi). Under the optimal conditions, the linear range was from 1.0 to 40.0 ng g(-1). The limits of detection and limits of quantitation of the six carbamates (metolcarb, arprocarb, carbaryl, isoprocarb, fenobcarb, and diethofencarb) were 0.3-0.5 ng g(-1) and 0.9-1.5 ng g(-1) for benincasahispida sample and 0.5-1.0 ng g(-1) and 1.5-3.0 ng g(-1) for pakchoi sample, respectively. The relative standard deviations (RSDs) for the intra-day precision at the analyte concentration of 40 ng g(-1) are from 2.3 to 8.2% (n = 5) and the inter-day RSDs (n = 5) are from 4.5 to 9.2%.