Liquid chromatographic determination of Vitamin D3 in infant formulas and fortified milk

An isocratic reverse-phase liquid chromatographic (LC) method with electrochemical (EC) detection has been developed and validated for determining Vitamin D3 in fortified milk and infant formulas. LC-EC determination provides linear responses in the range from 0.03 to 0.7 μg Vitamin D3/ml, with inter- and intra-day variations (R.S.D.%) of 4.1 and 4.4, respectively, and detection and quantification limits of 0.012 ng in assay (48 ng/100 g of sample) and 0.039 ng in assay (156 ng/100 g of sample), respectively. Application of the method to a set of infant formulas and fortified milk confirmed its usefulness.