QUANTITATIVE-DETERMINATION OF SULFUR-OXYGEN ANION CONCENTRATIONS IN AQUEOUS-SOLUTION - MULTICOMPONENT ANALYSIS OF ATTENUATED TOTAL REFLECTANCE INFRARED-SPECTRA

The multicomponent analysis of FT-IR attenuated total internal reflect ance spectra of mixtures of sulfur-oxygen anions provides an accurate noninvasive method for their quantitation. The use of spectral artifac t basis functions obtained from the singular value decomposition of a difference spectra matrix results in a marked increase in accuracy. Fu rther improvements in accuracy are attained with the use of multicompo nent spectra as basis functions. The analysis of a series of solutions of sulfur-oxygen anions ranging in concentration from 0.0005 to 0.032 3 M resulted in a root-mean-square error of 0.0002 M. In an in situ ex periment in which the anaerobic decomposition of aqueous sodium dithio nite was observed in ca. 1.5-min intervals over a 30-min period, the m ethod was shown to account continuously for total sulfur and average o xidation state while simultaneously measuring the concentrations of se ven components at each interval.