Analytical Method for Aflatoxins and Aflatoxicols in Cereals, Nuts and Their Products

An analytical method to determine aflatoxins M1 and M2, as well as aflatoxicols I and II, with high recovery from cereals and nuts was developed. Aflatoxins M1 and M2, and aflatoxicols I and II, were extracted from cereals and nuts with methanol-1% sodium chloride solution (55:45) and fat was removed with n-hexane. The solvent extracts were transferred to chloroform, then the chloroform layer was evaporated and the residue was subjected to thin-layer chromatography after being taken up in a small amount of chloroform. The silica gel plate was developed with methanol-ether-chloroform (7:10:70) for separation of aflatoxins B, G and M group and the aflatoxicol group.When it was desired to separate aflatoxins and aflatoxicols in a sample, the chloroform layer was chromatographed on a silica gel column using ether (for elution of aflatoxicols I and II) and methanol-chloroform (3:97) (for elution of aflatoxins B1, B2, G1, G2, M1 and M2) as developing solvents. The eluates containing aflatoxins and aflatoxicols were each evaporated to dryness and the residues were subjected to thin-layer chromatography after being taken up in a small amount of chloroform. Thin-layer chromatography was performed on silica gel plates with ether (for separation of aflatoxicols I and II) and n-amyl alcohol-acetone-chloroform (8:10:80) (for separation of aflatoxins M1 and M2) as developing solvents. A fluorodensitometer was used for quantitative analysis.The average recoveries were 85% for aflatoxin M1, 66% for M2, 85% for aflatoxicol I and 88% for II from artificially contaminated pistachio.