Fluorimetric determination of aflatoxin M1 in cheese.

A simple and sensitive method is proposed for the determination of aflatoxin M1 in cheese. The ground cheese sample is extracted with acetone-water (3 + 1). Acetone is evaporated under vacuum, and the aqueous phase is passed through a C18 disposable cartridge. After the cartridge is washed with acetonitrile-water (1 + 9), the toxin is eluted with acetonitrile. The extract is then cleaned up on a silica cartridge. Final analysis is performed by 2-dimensional thin layer chromatography (TLC) combined with fluorodensitometry or by liquid chromatography on a reverse phase C18 column with fluorescence detection. Recovery is greater than 90%, and the coefficient of variation is 6% or less. The detection limit is in the range of 10 ng/kg. The identity of aflatoxin M1 is confirmed by formation of the M2a or acetyl-M1 derivative and rechromatography.

Systematic identification of antioxidants in lards, shortenings, and vegetable oils by thin layer chromatography.

A simple and reliable method is described for rapid identification of ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, ethoxyquin, gallates (lauryl, octyl, propyl), nordihydroguaiaretic acid, 3,3'-thiodipropionic acid, tocopherol, t-butylhydroquinone, and 2,4,5-trihydroxybutyrophenone in lards, shortenings, and vegetable oils. The antioxidants are extracted with 95% methanol, concentrated under vacuum at less than or equal to 45 degrees C, and analyzed by thin layer chromatography. Three elution solvents, 2 adsorbent types, 2 visualization sprays, and UV viewing at 254 and 36 nm are used. Sunflower and corn oil samples, fortified with 100 ppm antioxidant, were analyzed to establish to validity of the method.