Comparison of methods by TLC and HPTLC for determination of aflatoxin M1 in milk and B1 in eggs

Abstract

Milk and egg matrixes were assayed for aflatoxin M1 (AFM1) and B1 (AFB1) resp., by AOAC official and modified methods with detection and quantification by thin layer chromatog. (TLC) and high performance thin layer chromatog. (HPTLC). The modified methods: Blanc followed by Romer, showed to be most appropriate for AFM, anal. in milk. Both methods reduced emulsion formation, produced cleaner exts., no streaking spots, precision and accuracy improved, esp. when quantification was performed by HPTLC. The use of ternary mixt. in the Blanc Method was advantageous as the solvent could ext. AFM, directly from the first stage (extn.), leaving other compds. in the binary mixt. layer, avoiding emulsion formation, thus reducing toxin loss. The relative std. deviation (RSD%) values were low, 16 and 7% when TLC and HPTLC were used, with a mean recovery of 94 and 97%, resp. As far as egg matrix and final ext. are concerned, both methods evaluated for AFB1 need further studies. Although that matrix leads to emulsion with consequent loss of toxin, the Romer modified presented a reasonable clean ext. (mean recovery of 92 and 96% for TLC and HPTLC, resp.). Most of the methods studied did not perform as expected mainly due to the matrixes high content of triglycerides (rich on satd. fatty acids), cholesterol, carotene and proteins. Although nowadays most methodol. for AFM1 is based on HPLC, TLC detn. (Blanc and Romer modified) for AFM1 and AFB1 is particularly recommended to those, inexperienced in food and feed mycotoxins anal. and esp. who cannot afford to purchase sophisticated (HPLC, HPTLC) instrumentation. [on SciFinder (R)]