Determination of kojic acid in various commercial foods by HPLC

A simple method for the determination of kojic acid in various commercial foods by HPLC was developed. The kojic acid was extracted from the various commercial foods with 50% methanol solution. The extract was centrifuged, then the supernatant fluid was filtered through a 0.45μm membrane filter. The HPLC separation was performed on an RP-18 column with 0.1mol/L sodium dihydrogenphosphate-methanol (97:3) as the mobile phase. The recoveries of kojic acid spiked into foods at the level of 0.10g/kg were 73-96%, and the detection limit was 0.005g/kg. The proposed method was applied to the determination of kojic acid in 92 commercial foods. Kojic acid was detected in 1 sample of crab and 2 samples of beverages at the levels of 0.03g/kg, 0.20g/kg and 0.03g/kg, respectively. The identity of kojic acid in these foods was confirmed using a photodiode-array detector.