Graphene Reinforced Hollow Fiber Liquid Phase Microextraction for the Enrichment of some Phenylurea Residues in Milk Sample

Graphene, as a kind of novel and interesting carbon material, has gained much attention in recent years. In this paper, a new sample preparation technique, graphene reinforced hollow fiber liquid phase microextraction (G-HF-LPME), was developed and used to pre-concentrate some phenylurea herbicides (chlortoluron, isoproturon, diuron, monolinuron, and buturon) in milk sample prior to high-performance liquid chromatography-ultraviolet detection. Different parameters influencing the extraction efficiency of the G-HF-LPME were investigated and optimized. Under the optimized conditions, a good linearity was observed in the range between 10.0 and 400.0 mu g L-1 with the correlation coefficients ranging from 0.9911 to 0.9987. The limit of detection (S/N = 3) of the method was lower than 2.0 mu g L-1. The developed method is simple, efficient, and has been successfully applied to the determination of the phenylureas in milk samples.