Abstract
A confirmatory analytical method for aflatoxins in a complicated sample such as spices utilizing a column switching technique was developed. Using both DIOL and ODS columns as a pre-column and a main column, respectively, three applications of two-dimensional liquid chromatography for aflatoxins in sample extracts not fully refined were achieved. First, a fraction containing all aflatoxins B1, B2, G1 and G2 was separated from sample matrices within pre-column elution and reinjected into the main column followed by gradient elution. Second, a fraction containing only aflatoxin B1 was separated and analyzed in the same manner, that is to say, single peak heartcutting. The quantitative detection limits were 10μg/kg for G1 and 5μg/kg for the others in eight spices. Third, a large-volume sample injection was successfully accomplished. As a result, we could improve tenfold the quantitative detection limits. Over and above that, consideration of the reliability of identification in chromatographic analysis was carried out.
