HPLC-Orbitrap-MS for the Determination of B-Vitamins in Fruit Juices and Food Supplements

Accurate assay of vitamins in foods is a considerable analytical challenge due to the chemical complexity of matrices and molecular structures. Orbitrap MS technology coupled with liquid chromatography through electrospray ionization source (HPLC-ESI-MS) was applied for the simultaneous determination of seven B-vitamins (thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, and folic acid) in fruit juices and dietary supplements. The method employed an easy sample treatment procedure, involving direct dilution for juices and a fast solvent extraction for supplements. Chromatographic separation was achieved by a reversed-phase column with a gradient elution of water and acetonitrile. Mass spectrometry detection was performed in full-scan mode and using both positive and negative ionization to maximize sensitivity. The method was validated, demonstrating excellent linearity (R² > 0.998), acceptable accuracy (96%-112% for supplements, near 100% for juices with matrix-matched calibration), and good precision (RSD < 15%). The matrix effect was investigated and mitigated using a matrix calibration curve for fruit juices. Limits of detection and quantification were determined, indicating good sensitivity. The validated approach was successfully applied to the analysis of real samples, showing good agreement with label claims for supplements and confirming the expected vitamin levels in fruit juices, with freshly squeezed juices exhibiting higher concentrations than commercial ones.