On the possibility of analyzing substances by spectroscopy techniques in ultraviolet and visible regions without using standard composition samples

The possibility of performing a quantitative molecular analysis of substanc es by spectral methods in visible and ultraviolet regions without using sta ndard composition samples (certified reference materials) is considered. It is shown that the modern experimental technique of optical spectroscopy an d the methods developed for calculations of electronic-vibrational spectra allow not only qualitative studies of substances but also quantitative stan dardless analysis to be performed. Such an analysis can be carried out by u sing the integral absolute intensity of the entire broad band (slightly str uctured spectra) or by using the intensity of several bands and individual lines of the vibrational structure (fine-structured spectra). This permits substances and their mixture with close spectral properties to be analyzed. Estimated expected errors in the determination of concentrations are no hi gher than 30% at rather small amounts of a substance required for analysis (less than or equal to 1 mg) and low concentrations of impurity molecules u nder study (less than or equal to 10(-4)%).