THIN LAYER CHROMATOGRAPHIC TECHNIQUES FOR DETECTION OF SUDAN DYES IN PALM OIL

Abstract

Sudan dyes I, II, III & IV are synthetic, oil-soluble, red-coloured azo dyes. These dyes are suspected genotoxic carcinogens and have been used in the adulteration of palm oil products. Many experimental studies on animal specimen have confirmed the formation of tumour due to the presence of different Sudan dyes in food products. In this study, a Simple Thin Layer Chromatographic method is described for the qualitative detection of Sudan-I, II, III & IV in palm oil gotten from different markets. The study includes extraction of sample, preparation of Thin Layer Chromatography (TLC) plates, Separation, detection and visualization of dyes on TLC plates. The dyes were extracted with solvent Acetonitrile. Sample extracts were decanted and analysed by simple thin layer chromatography in hexane, chloroform and acetic acid solvent system. The chromatograms of samples and standards were stained with Iron (ii) chloride stain and further evaluated in term of Rf values. Out of the five samples analysed the Rf values of the colouring spots from the three samples L2, L3 and L4, matched the standards (S2). It is therefore, concluded that samples L2, L3 and L4 contain Sudan IV dye. Without using any derivation, the limit of detection (18mg/L for S2 (Sudan IV dye) and 10mg/L for SI (Sudan III dye) was determined by visually determining if a spot was visible or not at a certain concentration of standard dye.