retention times when the third mobile phase was used, but aflatoxins B1 and B2 lower than 10 ng g1 could not be detected. It appears that the sensitivity decreased when the mobile phase contained more than 70% water (mobile phases 2–4). The first mobile phase was chosen in the present study as it gave not only higher sensitivity but also with shorter retention time. This composition was also used by Akiyama et al. (2001).