The mobile phase was water:methanol:acetonitrile
(4:1:1, v/v/v) at a flow rate of 1.5 ml/min and the limit of detection
was 1 ng/ml of B1 and G1 and 0.8 ng/g of B2 and G2. Pure aflatoxin solutions were
used as external standard (Sigma-Aldrich, St. Louis,MO,