High-performance liquid chromatography method for the determination of folic acid in fortified food products

Reversed-phase high-performance liquid chromatography, coupled with coulometric electrochemical detection, was successfully applied for the quantification of added folic acid (FA) in fortified fruit juices and cereal products. The method allowed good separation of the 5-HCO-H4 folate and folic acid in cereal samples. The retention times of vitamins were repeatedly determined by isocratic elution using 40 mM sodium phosphate dibasic, heptahydrate buffer, and 8% acetonitrile (v/v) (0.9 mL/min, pH 5.5) as mobile phase with the Supelco LC 18 column 5 mu m (25 cm 4.6 mm). Folate concentrations were measured using a trienzyme (hog kidney folate conjugase, alpha-amylase, and protease) folate extraction method.