Determination of Some Water-Soluble and Fat-Soluble Vitamins in Tears and Blood Serum of Infants and Parents By Liquid Chromatography/Mass Spectrometry

A subset of water-soluble vitamins (WSV) and fat-soluble vitamins (FSV) were detected and quantified in human tears and compared with blood serum levels. This is the first demonstration of vitamin detection simultaneously in tears and blood serum levels in infants and parents. Samples were from 15 four-month-old infants and one of their parents. The vitamin levels were compared between tears and serum in a single subject as well as between infants and parents for the same sample type. Further, concentration results were compared against nutritional information. WSV and FSV were detected with a C₁₈ analytical column through two HPLC-ESI-MS/MS 16 min and 18 min methods, respectively. H₂O and acetonitrile (ACN) containing 0.1% formic acid were WSV mobile phases while 1:9 H₂O/ACN and methanol containing 5 mM ammonium formate were FSV mobile phases. Vitamins B₁ (thiamine), B₂ (riboflavin), B₃ (nicotinamide) and E (α-tocopherol) were routinely detected in tears and serum while A (retinol) was detected in serum. WSVs B₅ and B₉ were also detected in tears and blood serum samples however the recovery and precisions found not to be sufficiently reliable. LODs determined in real tears were 0.075-1.7 ng for WSV and 0.24 ng for vitamin E. In contrast, LODs determined in serum were 0.057-0.66 ng for WSV and 1.4 and 0.43 ng for FSVs A and E, respectively, above the clinically reported normal range concentrations. The assays precision and accuracy were validated with %RSD of 2.2-10% and recoveries of 84.0-109.7% for all vitamins. Results demonstrated higher mean values for WSV levels in tears in compared to serum and also in infants in compared to parents. FSV E levels were lower in tears than serum with not significant difference between infants and parents levels while vitamin A was higher in parents than infants. Strong positive correlations were found between tear vs. serum vitamin E for both infants and parents while a slight positive correlation was detected for parent tears vs. serum B₁. Correlations between infant vs. parent were very strong for tears vitamins E and B₂ and serum vitamins E and B₂. A slight correlation was found for vitamin B1 in infant vs. parent tears and serum. Vitamin levels were also cross-correlated with results from self-reported nutritional questionnaires. Results suggest, with additional optimizations to results presented herein, that tears may be a viable biofluid to monitor for nutritional health assessments to speed deficiency diagnoses in infants and parents. Advantages to tears include less invasive sample collection and simplified sample preparation for analysis.