Molar absorptivities of aflatoxins B-1, B-2, G(1), and G(2) in acetonitrile, methanol, and toluene-acetonitrile (9+1) (modification of AOAC official method 971.22): Collaborative study

Four laboratories participated in a mini-collaborative study of AOAC Offici al Method 971.22, Standards for Aflatoxins, Thin-Layer Chromatographic Meth od, to extend the method to 3 replacement solvents for benzene for calibrat ion of standard aflatoxin solutions. Triplicate test sample vials, each con taining 25 mu g of the respective aflatoxin for each of the 4 aflatoxins an d for each of the solvents, were prepared and sent to each collaborator. Th e collaborators dissolved the aflatoxin in each vial in 2 mt solvent, measu red the UV spectrum, and reported the absorptivity maxima near 350 nm, The concentrations of the aflatoxins in the test samples were determined by dis solving identical test samples in benzene-acetonitrile (98 + 2) and followi ng the procedure described in AOAC Official Method 971.22, These concentrat ions were, in turn, used to determine the molar absorptivities in the other 3 solvents (see Table 1), AOAC Official Method 971.22 has been modified to extend its applicability to 3 replacement solvents for benzene for calibra tion of standard aflatoxin solutions.