Simultaneous analysis of folic acid and pantothenic acid in foods enriched with vitamins by stable isotope dilution assays

Abstract

Folic and pantothenic acid were quantified in multivitamin products by stable isotope dilution assays using [ 2 H 4] folic acid and [ 13 C 3, 15 N] pantothenic acid as the internal standards. Detection was achieved by liquid chromatography/mass spectrometry which enabled unequivocal determination of the vitamins. Due to the very simple extraction procedure, analysis of the vitamins was completed within 2 h. When analyzing multivitamin sweets, the intra-assay and inter-assay coefficient of variation was 3.2% ( n=5) and 3.1% ( n=5) for folic acid and 4.5% ( n=5) as well as 6.5% ( n=7) for pantothenic acid, respectively. Along with the precision data, recovery values of 99.4% for folic acid and 103% for pantothenic acid at addition levels of 6 mg/kg and 600 μg/kg, respectively, to starch products proved the accuracy of the new method. Application of the stable isotope dilution assay to fruit juices, whey products, cereals, sweets, pharmaceuticals, wheat flour and salt fortified with one or both vitamins revealed that for the majority of products the labeled pantothenic acid contents were exceeded by about 30%, whereas for folic acid also significantly lower contents than the label claim were found.