Separation of Sudan dyes from chilli powder by magnetic molecularly imprinted polymer

A simple method based on magnetic molecularly imprinted polymers (MMIPs) for the separation of Sudan dyes from chilli powder samples has been developed. The MMIPs were synthesized as follows: the Fe3O4 nanoparticles were encapsulated with a SiO2 shell and functionalized with CHCH2, then the polymers were further fabricated by surface-imprinted polymerization using Sudan IV as template molecule, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross-linking agent. The prepared MMIPs were characterized by scanning electron microscope, Fourier transform infrared spectrometry and physical property measurement system. The isothermal absorption experiment, kinetics absorption experiment and selectivity of MMIPs were tested. The analytes were determined by high performance liquid chromatography. Under the optimal conditions, the limits of detection of the four Sudan dyes are 6.2, 1.6, 4.3 and 4.5 ng g−1, respectively. The precision expressed as relative standard deviation ranging from 4.8% to 9.1% was obtained. In all three fortified levels (25, 250 and 2500 ng g−1), recoveries of Sudan dyes were in the range of 79.9–87.8%.