Possibilities of density functional theory in standardless quantitative spectral analysis

Density functional theory can be used in the quantitative analysis of substances by their IR spectra in cases when high precision is not necessary or certified reference samples are principally unavailable or are difficult to obtain. IR spectra of 30 complex organic molecules including different heteroatoms (Br, Cl, F, N, O) were calculated using the Gaussian98w program (6-31G) basis set. The calculated spectra were compared with experimental ones, and quantitative inverse spectral problems (calculation of concentrations) were solved for all of the molecules studied. It was shown that the found concentrations for the majority of the studied substances differ from their true concentrations by no more than 30%, which is acceptable, for example, for ecological monitoring.