Reversed-phase liquid chromatography on an amide stationary phase for the determination of the B group vitamins in baby foods.

A liquid chromatographic method for the separation and determination of several water-soluble vitamins of the B group is proposed. The procedure is based on the use of a new amide-based stationary phase, which avoids the need of using the ion-pair technique, leading to narrower peaks and a simpler mobile phase. Analyses were performed by gradient elution with acetonitrile-phosphate buffer as mobile phase and using a photodiode array detector. Specificity was demonstrated by the retention characteristics, UV spectra and by comparing the peak purity index with commercial standards. Linearity, precision, recovery and sensitivity were satisfactory. The vitamins are extracted from the baby food using a single digestion with hydrochloric acid followed by enzymatic digestion with taka-diastase. The method was successfully applied to the determination of nine vitamins: thiamine, riboflavin, nicotinamide, nicotinic acid, pyridoxine, pyridoxal, folic acid, cyanocobalamine and inosine in different baby foods as infant formulas, cereals and fruit products. Validation was performed using two certified reference materials.