Comparison between Conventional Spectral Analysis Methods, Chemometrics, and Two-Dimensional Correlation Spectroscopy in the Analysis of Near-Infrared Spectra of Protein

Abstract

The present study has aimed at comparing three methods for analyzing near-infrared (NIR) spectra: conventional spectral analysis methods, chemometrics, and generalized two-dimensional (2D) correlation spectroscopy. In a comparison of these approaches, NIR spectra were measured for aqueous solutions of human serum albumin (HSA) with the concentration range of 0.5–5.0 wt %. Synchronous and asynchronous 2D correlation spectra were generated from the concentration-dependent NIR spectral variations of HSA in distilled water. The first and second loadings plots were calculated for principal component analysis (PCA) models based upon the above NIR spectral data. It was found that slice spectra calculated from the synchronous spectra are very close to the first loadings plots and that slice spectra from the asynchronous spectra have a close resemblance to the second loadings plots. The reasons why the synchronous and asynchronous spectra bear close resemblance to the first and second loadings plots for the PCA model, respectively, are discussed in the paper.

Aquaphotomics: Near Infrared Spectroscopy and Water States in Biological Systems

“…NIR spectrum of the solvent (i.e., water) has been found to contain significant information about its solutes (Tsenkova 2009). In previous research, protein solutions (Murayama et al 2000), biomolecular water solutions (Murayama et al 2000;Tsenkova et al 2004), suspensions of small particles in water and various biological systems such as cells, plants, animal body fluids and tissues have been analyzed with NIR (Tsenkova 2009(Tsenkova , 2010Tsenkova et al 2001Tsenkova et al , 2004Jinendra 2010;Jinendra et al 2010;Kinoshita et al 2012;Matija et al 2012;Nakakimura et al 2012). In these studies, well known water absorbance bands have been observed under various perturbations (i.e., concentrations of solutes (Nakakimura et al 2012), nano particles (Matija et al 2012;Tsenkova et al 2007a), molecules which don't absorb (Tsenkova et al 2007a;Gowen et al 2013) in the NIR range, temperature (Segtnan et al 2001;Maeda et al 1995), light illumination, etc.).…”

“…Some of them have been newly discovered (Tsenkova 2009). In research carried out at Biomeasurement Technology Laboratory at Kobe University, Japan, water has been perturbed with lactose, human serum albumin (HSA) (Murayama et al 2000), different isomers of prion protein (PrP) (Tsenkova et al 2004), NaCl (Gowen et al 2013), metals (Putra et al 2010;Tsenkova et al 2007b) and other solutes at various concentrations. The most prominent wavelengths with highest variations caused by the used perturbations were identified in the spectra through multivariate analysis.…”

Use of genetic algorithms with multivariate regression for determination of gelatine in historic papers based on FT-IR and NIR spectral data

“…The low NIR absorption coefficients are also an analytical advantage, since they allow the radiation to penetrate deeply through the inhomogeneous material and hence the direct analysis of samples in reflectance mode without further pre-treatments to be accomplished. A few studies exist on proteins with detailed band assignments [38].…”

2 D Correlation Spectroscopy in Vibrational Spectroscopy

“…71 Of note in Figure 50(a) is the appearance of a cross-peak at (6764, 1706) cm 1 . It had been reported that a Raman band at 1706 cm 1 due to the CDO stretching mode of the CDO Ð Ð Ð H-O species is (1) and its blends with PVPh of contents 5 (2) and 10 (3) Temperature (°C) 60 identified in the one-dimensional spectra only for blends containing more than 33 wt% PVPh. Thus, the observation of this band in the synchronous spectrum for the blends with PVPh content from 1 to 10 wt% demonstrates the usefulness of the generalized 2D correlation in analyzing polymer blends containing a low-level minority component.…”