Analysis of FT-IR spectroscopic data: The Voigt profile

Abstract A novel spectral analysis technique is presented for the determination of peak areas from spectra in which there are multiple overlapping peaks. The technique involves a combination of Fourier spectral analysis and profile modeling. Although the technique presented could be applied to many different types of problems (analysis of UV spectra or chromatographic results) it is applied here to the problem of determining, from Fourier transform infrared (FT-IR) spectra, the peak areas which correspond to monomeric and hydrogen-bonded species. For FT-IR spectra it is found that the Voigt profile is better than either the Lorentzian or Gaussian profiles. Use of the Voigt profile leads to more accurate and descriptive spectral peak parameters and, in turn, to more accurate determinations of concentrations of monomeric and hydrogen-bonded species. The technique is demonstrated using the carbonyl peaks (monomeric and hydrogen-bonded) in the acetone/methanol/carbon tetrachloride system.