Simultaneous Sensing of H2O, D2O and HOD through Peroxo Vibrations

Detection of HOD simultaneously in the presence of a mixture of H2O and D2O is still an experimental challenge. Till date, there is no literature report of simultaneous detection of H2O, D2O and HOD based on vibrational spectra. Herein we report simultaneous quantitative detection of H2O, D2O 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 H2O and D2O. Due to the formation of different nature of hydrogen bonding between peroxide and solvent molecules (H2O, D2O and HOD), vibrational frequency of peroxo bond is significantly affected. Mixtures of different H2O and D2O concentrations produce different HOD concentrations and that lead to different intensities of peaks positioned at 897, 823 and 867 cm(-1) indicating H2O, D2O and HOD, respectively. The lowest detection limits (LODs) were 0.028 mole fraction of D2O in H2O and 0.046 mole faction of H2O in D2O. In addition, for the first time the results revealed that the cis-peroxide forms two hydrogen bonds with solvent molecules.

Automated summary

We successfully detected H2O, D2O, and HOD simultaneously in a reaction mixture using resonance Raman and surface-enhanced resonance Raman spectroscopy based on the peroxide vibrational mode. Bridged polynuclear peroxo complexes were synthesized in different H2O and D2O solvent mixtures, and the vibrational frequency of the peroxo bond was significantly affected by the different types of hydrogen bonding formed with solvent molecules (H2O, D2O, and HOD). Different concentrations of H2O and D2O resulted in varying HOD concentrations, which were indicated by peaks at 897, 823, and 867 cm(-1) for H2O, D2O, and HOD, respectively. The lowest detection limits were 0.028 mole fraction of D2O in H2O and 0.046 mole fraction of H2O in D2O. Additionally, the results revealed for the first time that the cis-peroxide forms two hydrogen bonds with solvent molecules.