A Dataset of Theoretical Concentrations and ATR-FTIR Spectra for Quantitative Analysis of Water Isotopologues (H2O, HDO, D2O)

[Background] The accurate molecular-level quantification of water isotopologues (H2O, HDO, and D2O) remains a significant analytical challenge in fields such as nuclear energy and materials science. Current standardized methods, including the Chinese National Standard GB/T 44647-2024, are limited to measuring total deuterium content using transmission-mode FTIR and cannot differentiate between HDO and D2O molecules. This inability to distinguish individual species restricts advanced applications in heavy water reactor monitoring and deuterated material analysis. Although ATR-FTIR offers potential for in-situ and rapid analysis, a systematic methodology and public benchmark dataset for molecular-specific quantification are still lacking. [Purpose] This study aims to develop a robust quantitative method using ATR-FTIR spectroscopy to simultaneously discriminate and quantify H2O, HDO, and D2O molecules in heavy water samples. [Methods] A series of heavy water samples with varying initial D2O concentrations were prepared as the research subjects. Spectra were collected using an ATR-FTIR spectrometer equipped with a diamond crystal under ambient temperature and constant pressure application to ensure optical contact and reproducibility. Three characteristic infrared absorption peaks were selected for quantitative analysis: the H–O–H bending vibration (δ(H—O—H)) at ~1640 cm-1 was integrated to quantify H₂O, the D—O—D bending vibration (δ(D—O—D)) at ~1200 cm-1 was used for D2O quantification, and the O—D stretching vibration (ν(O—D)) at ~2500 cm-1 was applied to determine the total O—D bond concentration. The HDO concentration was indirectly calculated using the stoichiometric relation. Each sample was measured in triplicate to evaluate repeatability. [Results] The method demonstrated high precision, with all peak area measurements exhibiting a relative standard deviation (RSD) of less than 7% across five concentration levels. Excellent linearity was observed in the calibration curves for all three species, with coefficients of determination (R2) exceeding 0.99. In blind testing, the deviation for D2O quantification was +5.2%, and that for O—D bonds (directly related to HDO) was +6.3%. The quantification of H₂O showed a larger deviation of 14.8%, primarily due to interference from environmental moisture adsorption. [Conclusions] This study establishes a novel, reliable, and practical ATR-FTIR-based method for the simultaneous quantification of H2O, HDO, and D2O, effectively overcoming the limitations of existing standards. The public release of the methodology and dataset provides a critical benchmark for future development of molecular-specific isotope analysis tools. These findings offer a valuable technical solution for real-time monitoring in nuclear reactors and precision detection in deuterated material research, with further improvements in H2O accuracy expected through sample isolation techniques such as vacuum application.​