Measurement of ascorbic acid kinetics in man using stable isotopes and gas chromatography/mass spectrometry

The feasibility of studying ascorbic acid kinetics in man using stable isotope-labelled tracers and gas chromatographic (GC) separation followed by mass spectrometric (MS) quantitation was assessed. Preliminary studies with 13C-labelled material showed that although better precision at low levels could be achieved using the GC/combustion/MS technique, consideration of likely enrichments in a human study made the simpler GC/MS method just as suitable. On this basis, a small pilot study of the kinetics in man was carried out. The enrichment of the ascorbic acid in plasma was measured for a 24 h period after oral administration of 13C-labelled material. The results were fitted to a simple three-compartment model and rate constants and pool sizes were deduced. The results obtained are comparable to those obtained in other published studies, from which we conclude that the technique may be useful as a non-invasive method for the assessment of nutritional status in a variety of populations.