Determination of banned Sudan dyes in food samples by molecularly imprinted solid phase extraction - high performance liquid chromatography

A method for molecularly imprinted solid-phase extraction of banned Sudan azo-dyes from food samples was investigated. The molecularly imprinted polymer was obtained by suspension polymerization using 1-(4-chlorophenyl)azonaphthalen-2-ol as the mimic template. The molecular recognition properties of imprinted beads were evaluated for use as a solid-phase extraction sorbent, in order to develop a selective extraction protocol for the Sudan class of dyes. The optimised extraction protocol resulted in a reliable MISPE method suitable for HPLC analysis. It was selective for the main analyte, Sudan I and the related azo-dyes Sudan II, III, IV, Sudan Red B and Sudan Red 7B, while the permitted azo-dyes Allura Red AC, Neococcin and Sunset Yellow FCF were not extracted. The method was tested for Sudan I, II, III and IV in five different food samples (hot chilli pepper, hot chilli tomato sauce, sausage, tomato sauce and hard boiled egg yolk) at three concentration levels (15 – 100 - 300 μg/g). It demonstrated itself to be insensitive to the presence of different complex matrices, precise, accurate and with good recovery rates (85-101%). The limit of detection and limit of quantification were satisfactory for most analytical determinations