Procedure for the quantitative determination of mixtures of nucleic acid components based on multivariate spectrophotometric acid-base titrations

A new procedure for the quantitative determination of mixtures of nucleic a cid components, based on continuous spectrophotometric acid-base titrations and multivariate curve resolution, is proposed, The procedure simultaneous ly takes into account the spectroscopic and acid-base properties of the com pounds, which leads to a higher selectivity. Furthermore, quantitative dete rmination 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 compound s. An additional problem can be encountered in some mixtures if species spe ctra or species concentration profiles are practically identical (rank over lap). However, even in the presence of these rank difficulties, accurate qu antitation with prediction errors lower than 5% was obtained, The presence of unknown and uncalibrated interferences in the samples does not affect th e quantitative determination of the analyte of interest. The proposed proce dure was successfully applied to the analysis of real samples (pharmaceutic als) using synthetic external standards.