Selectivity of the optical-absorption method based on an instrumental pick out of Fourier components in the absorption spectrum

The introduction of interference–polarization filters (IPFs) in the structure of an optical–absorption analyzer makes it possible to pick out a harmonic (a Fourier component of the absorption spectrum) providing measurement with the highest sensitivity. The selectivity of such a method of analysis is determined by overlapping the oscillations of the measured and interfering components. By the example of measurement in benzene in the presence of an interfering component (toluene), the possibility is considered for the optimization of selectivity due to the variation of the path-difference dispersion for ordinary and extraordinary interfering rays. The metrological characteristics of the interference–polarization analyzer of C₆H₆ confirming the results of calculations are given.