Three 500g subsamples were picked up from each of ground rice samples with aflatoxin total level 1 (containing < 30 ppb and < 4 ppb) and aflatoxin total level 2 (AFT ≥ 30 ppb and ≥ 4 ppb) and were treated with 1N aqueous CA for 15 min (3 ml/g of contaminated rice) before being filtered through a micro-fiber filter to get rid of excess water and dried in a vacuum oven at 40 C for 48 h.