This paper presents a new technique for using an IR spectrometer to measure the protium and deuterium concentrations (aH and aD) in heavy water. This technique makes it possible to determine the absolute protium concentration in highly concentrated heavy water to within 60.001%.
T. V. Voronina and O. A. Fedorchenko, "Measuring the protium concentration in highly concentrated heavy water by IR spectrometry," J. Opt. Technol. 70, 80-84 (2003)