基于氧化石墨烯气凝胶固相萃取柱检测有机磷农药
摘要
<p id=C2>A graphene oxide aerogel was prepared and directly filled in a solid phase extraction (SPE) column without the aid of silica or other substrates. The aerogel was used to extract and detect residual organophosphorus pesticides (phoxim, temephos, fenthion, and fenitrothion) in food, and exhibited good elasticity and high mechanical strength. The graphene oxide aerogel was prepared by freeze-drying. Its morphology and physical properties were characterized by scanning electron microscopy, infrared spectroscopy, and BET surface adsorption. Results proved the successful synthesis of the graphene oxide aerogel. Scanning electron micrographs of the aerogel exhibited a layered and fold structure, with a surface area of 740.51 m<sup>2</sup>/g. The effect of experimental conditions on the extraction recovery of organophosphorus pesticides was systematically studied through a series of single-factor experiments. Due to limited adsorption sites, sample volumes of 5-60 mL were investigated, and 15 mL was determined was the optimum sample volume. The rate of sample loading was investigated in the range of 0.8-3.0 mL/min. When the rate of sample loading was higher than 3.0 mL/min, the insufficient contact between the analytes and sorbent appeared to cause a decrease in the extraction recovery. A lower rate of sample loading would prolong the operation time due to the re-elution of organophosphorus pesticides. The sample pH was optimized from a pH range of 2-11. An acidic solution was found to be good for inducing electrostatic interactions between the graphene oxide aerogel and organophosphorus pesticides. The maximum extraction recoveries were obtained at pH 4. Three eluents (acetonitrile, methanol, and acetone) were explored for optimization, and results showed that acetonitrile was the most appropriate eluent. The eluent volume (0.6-1.2 mL) was also investigated, and the optimal value was found to be 1.0 mL. Compared with commercial extraction materials including C18 s