The ability to measure low levels of 2H-labeling is important in studies of metabolic flux, e.g. one can estimate lipid synthesis by administering 2H2O and then measuring the incorporation of 2H into fatty acids. Unfortunately, the analyses are complicated by the presence of more abundant naturally occurring stable isotopes, e.g. 13C. Conventional approaches rely on coupling gas chromatographic separation of lipids with either quadrupole-mass spectrometry (q-MS) and/or pyrolysis-isotope ratio mass spectrometry (IRMS). The former is limited by high background labeling (primarily from 13C) whereas the latter is not suitable for routine high-throughput analyses.