Spectroscopic Quantitative Analysis of Strongly Interacting Systems: Human Plasma Protein Mixtures

Abstract

Blood plasma protein infrared spectra, while qualitatively very similar, display subtle differences in the frequencies and intensities of absorption bands. These small differences are sufficient to permit an accurate quantitative analysis of mixtures of these proteins. In this paper we examine the performance of some alternative methods of spectroscopic quantitative analysis in determining the concentrations of proteins in aqueous solutions. The widely-used K matrix method, using sloping baselines and intercept functions, was found to be inadequate for these determinations. In contrast, a method based on the little-known Q matrix approach, augmented by a robust equation solver, yielded results with a sufficient degree of accuracy to make it a viable tool for use in the study of proteins at solid interfaces and for more general applications in the field of protein chemistry.