The use of infrared spectrophotometry for measuring body water spaces, Clin

total body water by the deuterium isotope dilution method uses gas isotope ratio mass spectrometry (IRMS), which is both expensive and time-consuming. We investigated an alternative method, using Fourier transform infrared spectrophotometry (FTIR), which uses less expensive instrumentation and requires little sample preparation. Method: Total body water measurements in human subjects were made by obtaining plasma, saliva, and urine samples before and after oral dosing with 1.5 mol of deuterium oxide. The enrichments of the body fluids were determined from the FTIR spectra in the range 1800 –2800 cm21, using a novel algorithm for estimation of instrumental response, and by IRMS for comparison