Improved liquid chromatographic determination of riboflavin in milk and dairy products

Reported here is a simple liquid chromatographic (LC) method for the determination of riboflavin in milk (liquid, evaporated, and dry), yogurt, and cheese. The method involves passing liquid samples or filtrates of semisolid and solid samples through a C18 cartridge. Retained riboflavin is then eluted with an aliquot of 50% methanol in 0.02M acetate buffer of pH 4. A volume of the eluate is injected into the LC system consisting of a C18 column, a solvent of water-methanol-acetic acid (65 + 35 + 0.1, v/v) with a flow rate of 1 mL/min, and a UV detector set at 270 nm. The method is precise and accurate and compares favorably with the present AOAC method. Moreover, it involves fewer sample preparation steps and has a total analysis time of less than 1 h.