IMPROVED PROCEDURES FOR MEASUREMENT OF AFLATOXINS WITH THIN LAYER CHROMATOGRAPHY AND FLUOROMETRY1

Abstract

Optimal resolution of aflatoxins B1, B2, G1, and G2 was obtained when thin layer Chromatoplates equipped with a 0.25 mm layer of silica gel (Adsorbosil-5) were used within 2 hr after heat activation and when plates were developed in an unlined unequilibrated tank containing methanol and chloroform (1:99 v/v). Plates were further improved for fluorometric scanning by extending the distance of the solvent front from 15 to 18 cm and by scoring the Adsorbosil-5 to provide narrow bands prior to spotting the sample. Chromatoplates treated as described were accurately scanned with a fluorometer (not a modified densitometer) and concentrations of aflatoxins were indicated by areas under peaks as drawn by an attached recorder. A satisfactory linear relationship was obtained between the emitted fluorescences expresed as the area under peaks and concentration of the four aflatoxins.