Background Correction in Multicomponent Spectroscopic Analysis Using Target Transformation Factor Analysis

Abstract

A principal components regression (PCR) is used to construct a calibration matrix for multicomponent spectroscopic analysis which corrects for background absorption due to variable concentrations of unknown species in a sample matrix. Mixed standards are used in the method, and spectra of the pure background components are not needed. The background correction capability of the method is demonstrated with the use of the UV spectra of aqueous standards prepared from cobalt (II) nitrate and nickel (II) nitrate. Known concentrations of chromium (III) nitrate were added to simulate a background which gave rise to relative concentration errors as high as 70% without the background correction capabilities of the method. With the background correction capabilities of the method, the relative concentration errors were reduced to less than one percent. Preliminary results are presented from an application of PCR to determine the concentration of two active ingredients in a pharmaceutical product in the presence of weakly absorbing tablet excipient materials.