Automated Method for the Determination of Deuterium Oxide in Water and Biologic Fluids

An automated system has been assembled for determination of deuterium oxide in water and physiologicfluids. The system consistsof an AutoAnalyzer sampler, pro-portioning pump, and dialyzer; a Perkin-Elmer infrared spectrophotometer; and a Sargent recorder. Reproducibility of peak heights showed a standard deviation of less than ± 1 mm. over a range of D20 concentrations from 0.125 to 1.000%. ETHODS FOR DETERMINATION of deuterium oxide (D00) using infrared spectrophotometry have been reported by a number of workers (1-3). These methods permit determination of D00 in biologic fluids with an accuracy and precision satisfactory for determination of total body water and similar problems. The use of an infrared spectrophotometer for measurement of 1)20 in water and biologic fluids offers possibilities for the automatioll of a method, with its apparent advantages. Colorim-eters and spectrophotometers covering the ultraviolet and visible ranges are now used in automated systems. A pen-position readout system for use with a strip-chart recorder and flow-through cells should permit use of an infrared spectrophotometer with the AutoAnalyzer. In view of tllese possibilities, the purpose of the present investigation was to automate the determination of D20 and to determine the accuracy and precision of the method when used for measurement of T)0 in water, urine, plasma, or whole blood. Materials and Methods Equipment The following instruments were arranged in a continuous system: (1) AutoAnalyzer sampler equipped with sample leveling and constant volume attachments; (2) proportioning pump; (3) dialyzer; (4) Perkin-Elmer Model 237 infrared spectrophotometer equipped with a pen