Comparison of analytical methods for aflatoxin determination in commercial chilli spice preparations and subsequent development of an improved method

A method for analysis of aflatoxins in commercial chilli spice preparations was developed. Initial work concentrated on identification of optimal recovery and binding of aflatoxins to immunoaffinity columns prior to analysis. An 80:20 methanol-water (%, v/v) extraction mixture gave the highest recovery (79-87%). Investigation of the efficiency of commercial immunoaffinity columns for clean-up i.e. binding of aflatoxins, indicated that the Vicam column performed better than R-Biopharm immunoaffinity column. A comparison of analytical methods was then undertaken using enzyme-linked immunosorbent assay (ELISA) and high performance liquid chromatography (HPLC) using either, post-column derivatisation by iodine in a reaction coil, or bromine derivatisation in a Kobra cell. ELISA had poor precision and a positive bias. Both HPLC methods performed well, however an increased sensitivity and recovery of aflatoxin detection was found for the Kobra cell compared with the iodine derivatisation method.