[Preparation and evaluation of Sudan Red I molecularly imprinted polymer]

The molecularly imprinted polymer (MIP) was prepared by precipitation polymerization using Sudan Red I as the template. To investigate the influence of porogenic solvent and the amount of template on recognition property, selective chromatographic evaluation and frontal chromatography were performed. The results indicated that the obtained MIP had the best affinity and selectivity to the template when the molar ratio of template to functional monomer was 1:8 and a mixture of 30 mL methanol and 10 mL acetonitrile was used as the porogenic solvent. The imprinted factor of optimal MIP for Sudan Red I was 2.32, and the total amount of the immobilized ligand was 0.50 micromol/g. This MIP displayed good specific recognition property for Sudan Red I and was used as the sorbent of solid phase extraction (SPE) to determine trace Sudan Red I in chili powders. The linear range was from 10 to 500 micromol/L with a correlation coefficient of 0.999. The detection limit was 3.3 micromol/L, the spiked recovery was between 95.87% and 98.41%, and the relative standard deviation (RSD) was lower than 3.1%. The developed method can be used for the routine detection of Sudan Red I in chili powders.