Synthesis and application of multi-walled carbon nanotubes–molecularly imprinted sol–gel composite material for on-line solid-phase extraction and high-performance liquid chromatography determination of trace Sudan IV

A novel composite material of multi-walled carbon nanotubes (MWNTs)–Sudan IV molecularly imprinted polymers (MIPs) was prepared by surface molecular imprinting technique in combination with sol–gel technology. The MWNTs–MIPs were evaluated by scanning electron micrograph (SEM), Fourier transform infrared spectroscopy (FT-IR), and adsorption experiments. The results showed that the MWNTs–MIPs exhibited good selective recognition to Sudan IV. The maximum saturated binding capacity (Qmax) is 63.2 μmol g−1. Applied as sorbent, the MWNTs–MIPs were used for the determination of trace Sudan IV in chilli powder by on-line solid-phase extraction–high-performance liquid chromatography (SPE–HPLC). The results showed that an enrichment factor of 741 was achieved with a loading flow rate of 1.0 mL min−1 for sampling 50 mL. The MWNTs–MIPs provided a fast and convenience determination platform for Sudan IV in real samples.