Chemometrics and two-dimensional correlation spectroscopy in the analysis of near-infrared spectra of protein

This article reports comparison in the analysis of near-infrared (NIR) spectra of protein in control serum between generalized two-dimensional (2D) correlation spectroscopy and multivariate analysis, particularly, principal component analysis (PCA). NIR spectra were measured for human serum albumin (HSA) in the control serum with the final concentration range of 2.4 - 7.4 wt%. The synchronous and asynchronous 2D correlation spectra were generated from the concentration-dependent MR spectral variations of HSA in the control serum. The same series of NIR spectra were also subjected to PCA. Comparison between the 2D correlation spectra and loadings plots for PCA has revealed that a power spectrum along the diagonal line on the synchronous spectrum resembles to the first loadings plots, while some slice spectra along particular wavenumbers of the asynchronous spectrum resemble the second loadings. The reasons why the synchronous and asynchronous spectra show good correspondence to the first and second loadings plots for PCA, respectively, are discussed in this paper.