Preparation of monolithic fibers based on dual functional monomers for solid-phase microextraction of sudan dyes in tomato sauce and egg yolk samples

Abstract

New monolithic fibers based on dual functional monomers were prepared and applied to the solid-phase microextraction and determination of sudan dyes (I, II, III and IV) in tomato sauce and egg yolk samples by coupling with high-performance liquid chromatography. Octadecyl methacrylate and vinylimidazole were used as functional monomers to copolymerize with divinylbenzene to form the monolithic fibers. The effect of the preparation conditions of the monolithic fibers on the extraction efficiencies was investigated in detail. Elemental analysis, infrared spectroscopy, mercury intrusion porosimetry and scanning electron microscopy were used to characterize the monolithic materials. In the optimized process, several extractive parameters including desorption solvent, extraction and desorption time, pH values and ionic strength in the sample matrix, were optimized thoroughly. Under the optimized extraction conditions, the limits of detection (S/N = 3) for the sudan dyes were 0.07–1.46 μg kg⁻¹ in tomato sauce and 0.14–2.07 μg kg⁻¹ in egg yolk, respectively. Method repeatability was achieved in terms of intra- and inter-day precisions, indicated by RSDs, which were both <10%. Satisfactory recoveries of spiked target analytes in these samples ranged from 71.4% to 110%, with RSD of less than 11%.