Pre-concentration of organophosphorus pesticides in aqueous environments and food extracts by modified magnetic graphene oxide synthesized from sugar beet bagasse waste

In the present research, graphene oxide (GO) nanosheets were synthesized by sugar beet bagasse as an agricultural waste. Then, the synthesized nanosheets were modified with magnetic nanoparticles to produce a hybrid of nanomaterials that can be used for magnetic solid-phase extraction (MSPE) of diazinon as a model of organophosphorus pesticides (OPPs) in environmental and food samples. The produced adsorbent was characterized by FT-IR spectroscopy, XRD analysis, SEM, and TEM. These results exhibited FeO nanoparticles with an average size of 17.22 nm were uniformly distributed on the surface of the GO nanosheets. Next, the effective experimental factors controlling the extraction recoveries such as desorption conditions, sorbent dosage, pH of analyte solution, extraction time, and concentration of analyte were assessed and optimized via response surface methodology (RSM) based on central composite design (CCD). Generally, the optimum adsorption condition was suggested by software (sorbent dosage = 0.35 g/L, pH = 5.04, extraction time = 8 min, and diazinon concentration of 12 µg/L), though in order to achieve the highest recovery, the target condition was investigated. Finally, the concentration of extracted analyte was quantified via a gas chromatography-nitrogen phosphorous detector (GC-NPD). The magnetically separable nanoadsorbent showed appropriate sustainability and reusability even after four cycles of sorption- desorption. The detection limit of method was 2.41 μg/L. Also, this procedure was successfully used for identification of diazinon in water, milk, and honey samples with the obtained results showing acceptable recovery values.