Evaluation and Improvement of Extraction Methods for the Analysis of Aflatoxins B1, B2, G1 and G2 from Naturally Contaminated Maize

The extraction procedure for aflatoxin determination in maize is based on a methanol–water (8 + 2 v/v) or an acetone–water (85 + 15 v/v) mixture. Initially, the extraction efficiency of two solvents was evaluated for each aflatoxin. Different results were obtained for highly contaminated maize: significantly higher levels of aflatoxin B1 were obtained by acetone–water, on the contrary higher levels of aflatoxin G2 were achieved by methanol–water. Then, acetone–water mixtures in different proportions (7 + 3, 6 + 4 and 5 + 5 v/v) were tested to improve the extraction of aflatoxin G2. Applying these extraction mixtures, the values both of aflatoxin B1 and of other aflatoxins were generally higher compared to those obtained by acetone–water 85 + 15; moreover, acetone–water (6 + 4) and (7 + 3) showed the best extraction efficiency for all aflatoxins.