Simultaneous Sensing of H₂ O, D₂ O and HOD through Peroxo Vibrations

Detection of HOD simultaneously in the presence of a mixture of H₂ O and D₂ O is still an experimental challenge. Till date, there is no literature report of simultaneous detection of H₂ O, D₂ O and HOD based on vibrational spectra. Herein we report simultaneous quantitative detection of H₂ O, D₂ O and HOD in the same reaction mixture with the help of bridged polynuclear peroxo complex in absence and presence of Au nanoparticles on the basis of a peroxide vibrational mode in resonance Raman and surface enhanced resonance Raman spectrum. We synthesize bridged polynuclear peroxo complex in different solvent mixture of H₂ O and D₂ O. Due to the formation of different nature of hydrogen bonding between peroxide and solvent molecules (H₂ O, D₂ O and HOD), vibrational frequency of peroxo bond is significantly affected. Mixtures of different H₂ O and D₂ O concentrations produce different HOD concentrations and that lead to different intensities of peaks positioned at 897, 823 and 867 cm^-1 indicating H₂ O, D₂ O and HOD, respectively. The lowest detection limits (LODs) were 0.028 mole fraction of D₂ O in H₂ O and 0.046 mole faction of H₂ O in D₂ O. In addition, for the first time the results revealed that the cis-peroxide forms two hydrogen bonds with solvent molecules.