An improved separation of aflatoxins

Abstract

Crude aflatoxin from a chloroform extract ofAspergillus flavus cultures on rice was precipitated with Skelly Solve B and chromatographed on 100–200 mesh silica gel columns, using ethyl acetate as eluant. On this column there was no separation of aflatoxins from each other, but most of the brown, oily material was removed. The next step in the purification was chromatography on 100–200 mesh silica gel columns with chloroform and 5% methanol/chloroform as eluants. A large part of the B₁ was purified, but B₂, G₁ and G₂ did not separate, and M₁ had a brown oil that prevented crystallization. The M₁ was purified by chromatography on Sephadex LH-20 with chloroform; the brown material was retained while the M₁ passed through. The separation of aflatoxin B₂, G₁, and G₂ was achieved by column chromatography on Silica Gel H for TLC. In addition, aspertoxin was separated and identified. The purity and identity of the compounds were established by 100 MHz NMR.