Abstract: Technologies for rapid equilibration for water isotope analysis are disclosed. In at least one illustrative embodiment, a vaporizer may include an injection block that defines a chamber and a septum positioned over an inlet of the chamber to seal the chamber. The chamber may be configured to be fluidly coupled to a pump to develop a vacuum within the chamber, and the septum may be configured to receive a needle that is inserted into the chamber. A thermally conductive wool may be positioned within the chamber and may be configured to receive a tip of the needle.

Abstract: Technologies for rapid equilibration for water isotope analysis are disclosed. In at least one illustrative embodiment, a vaporizer may include an injection block that defines a chamber and a septum positioned over an inlet of the chamber to seal the chamber. The chamber may be configured to be fluidly coupled to a pump to develop a vacuum within the chamber, and the septum may be configured to receive a needle that is inserted into the chamber. A thermally conductive wool may be positioned within the chamber and may be configured to receive a tip of the needle.

Abstract: A method of measuring energy expenditure in a living subject comprises: (a) administering a specified dose of doubly-labeled water (2H218O) to a living subject; (b) obtaining samples at three or more times of body water from the living subject; (c) measuring 2H/1H, 17O/16O and 18O/16O ratios in each of the obtained samples using optical spectroscopy; and (d) determining (1) a combined value of flux of body water and exhaled carbon dioxide from a change in measured 18O/16O over time, (2) a value of flux of body water alone from a change in measured 2H/1H over time, and (3) a reference value of isotopic background fluctuation from a change in measured 17O/16O over time. Using 17O measurements to estimate background fluctuations of the 2H and 18O decreases the required isotope dosing of subjects or decreases uncertainty at current dosing levels.

Abstract: A method of measuring energy expenditure in a living subject comprises: (a) administering a specified dose of doubly-labeled water (2H218O) to a living subject; (b) obtaining samples at three or more times of body water from the living subject; (c) measuring 2H/1H, 17O/16O and 18O/16O ratios in each of the obtained samples using optical spectroscopy; and (d) determining (1) a combined value of flux of body water and exhaled carbon dioxide from a change in measured 18O/16O over time, (2) a value of flux of body water alone from a change in measured 2H/1H over time, and (3) a reference value of isotopic background fluctuation from a change in measured 17O/16O over time. Using 17O measurements to estimate background fluctuations of the 2H and 18O decreases the required isotope dosing of subjects or decreases uncertainty at current dosing levels.