Use of graphene coated with ZnO nanocomposites for microextraction in packed syringe of carbamate pesticides from juice samples.

In this work, nanocomposites of reduced graphene oxide coated with ZnO were synthesized using a hydrothermal reduction strategy. Nanocomposite was then used as a sorbent for microextraction in a packed syringe, and its application to the extraction of carbamate pesticides from juice samples prior to high-performance liquid chromatography detection was demonstrated. Factors affecting the enrichment efficiency of the microextraction in a packed syringe procedure were optimized, which included desorption conditions, sample pH, salting-out effect, washing solution, and sample cycles. Under optimal conditions, the prepared materials exhibited excellent enrichment efficiency for carbamate pesticides. Good linearity existed in the concentration range of 0.5-200 ng/mL, with correlation coefficients of 0.9991-0.9997. The limits of detection of these carbamate pesticides were in the range of 0.23-1.21 ng/mL, and the average recoveries of the analytes at two spiked levels for real-sample analysis ranged from 90.5 to 104.2% with relative standard deviations of 3.6-5.9%.