Speciation of complex organic contaminants with Raman spectroscopy

摘要

Raman spectroscopy was utilized to acquire resolved spectra of the neutral and zwitterion involved in the tautomeric solution equilibrium of 3-hydroxypyridine. As these species exist in varying proportion to one another at different temperatures, spectral measurements across a series of temperatures was required. Previously determined microequilibrium and enthalpy constants allowed the calculation of concentrations at all temperatures. This allowed for the deconvolution of component Raman spectra by multiple linear regression. The spectra are found to be similar, but contain significant structurally related differences, sufficient to distinguish one species from the other. To our knowledge, resolved Raman spectra of tautomers in water has not previously been reported.