Effect of resolution on quantification in open-path Fourier transform infrared spectrometry under conditions of low detector noise. 1. Classical least squares regression

The effects of resolution, spectral window, and background type on the pred ictive ability of classical least squares regression (CLS) on spectra measu red by an open-path Fourier transform (OP/FT-IR) spectrometer were tested i n some detail. It is shown that the most accurate quantitative results are obtained by using equidistant backgrounds, reduced spectral windows, and lo w resolution. The effect of interfering compounds is shown to be particular ly serious when CLS regression is used to process OP/FT-IR spectra.