Abstract:
Deuterated water (2H2O) is used to measure total body water space for estimation of the total body protein and fat in sheep. In measurements, a few grams of 2H2O is injected intramuscularly and after equilibrium a blood sample is taken to assay 2H-enrichment. The enrichment in plasma is usually as low as 100 ppm. This is traditionally analysed by isotope ratio of mass spectrometry (IRMS), but the analysis is labour intensive and expensive. A novel and economical method using gas chromatography mass spectrometry (GCMS) has recently been developed to determine 2H-enrichment as low as 80- 500 ppm (Yang et al. 1998). The method is based on analysis of 2H-enrichment in 13C3-acetone after isotopic exchange of protons in water with hydrogens adjacent to the carbonyl group of acetone. The approach was modified in our laboratory for analysis of low 2H-enrichment in sheep plasma.
