A new procedure for the quantitative determination of mixtures of nucleic acid components, based on continuous spectrophotometric acid-base titrations and multivariate curve resolution, is proposed. The procedure simultaneously takes into account the spectroscopic and acid-base properties of the compounds, which leads to a higher selectivity. Furthermore, quantitative determination of an analyte in a complex mixture is performed using a synthetic solution as standard containing only the analyte of interest. An intrinsic difficulty in the analysis of spectrometric titration data is the presence of rank deficiency due to closure for the mixtures of two or more compounds. An additional problem can be encountered in some mixtures if species spectra or species concentration profiles are practically identical (rank overlap). However, even in the presence of these rank difficulties, accurate quantitation with prediction errors lower than 5% was obtained. The presence of unknown and uncalibrated interferences in the samples does not affect the quantitative determination of the analyte of interest. The proposed procedure was successfully applied to the analysis of real samples (pharmaceuticals) using synthetic external standards.

Multivariate curve resolution is applied to cyclic voltammetry (CV) data obtained in the study of Cd(II) complexation by glutathione (GSH). The relatively poor resolution of CV hinders the direct interpretation of raw data. The use of CV is improved by the combination of several chemometric techniques based on factor analysis:  singular-value decomposition, evolving factor analysis, and multivariate curve resolution with constrained alternating least squares optimization including a new peak-shape constraint. This multivariate analysis data treatment simultaneously reveals the formation of Cd(GSH)2 and Cd2(GSH)2 complexes, through the calculated concentration profiles, and allows the assignment of numerically obtained pure individual CV signals for the different Cd(II) ions present in solution (free and bound) and involved in the electrochemical process.