Is Digital Drying an Effective Method for Infrared Spectroscopy of Gaseous Biofluid?

In recent years, gaseous biofluid analysis has gained popularity as a diagnostic approach due to the noninvasive collection of gaseous bioprobes. Among many biofluids, human exhaled breath stands out as a promising option, providing strong evidence of volatile biomarkers for various diseases. However, identifying these biomarkers is challenging due to the high concentration of water vapor in exhaled breath. Various experimental techniques, such as mass spectrometry, electronic nose, infrared spectroscopy, etc., have demonstrated their potential as diagnostic tools. However, water vapor in exhaled breath poses a significant obstacle to metabolite identification across nearly all experimental methods, particularly in infrared spectroscopy-based diagnostics. Nevertheless, in addition to physical removal, careful analysis of the spectral behavior of water molecules enables highly accurate identification of disease-specific biomarkers using infrared spectroscopy. This study presents a comprehensive qualitative analysis of the infrared spectral features of gaseous water molecules.