Raman microspectroscopy and multivariate data analysis: optical differentiation of aqueous d- and l-tryptophan solutions

Abstract

The combination of Raman spectroscopy as a sensitive and selective optical measurement technique and multivariate data analysis forms a powerful tool for probing intermolecular interactions between enantiomers. In this study we demonstrate that the optical differentiation of aqueous D- and L-tryptophan solutions is possible using Raman spectroscopy and principal component analysis (PCA). The loadings of the PCA allow identifying these functional groups most relevant for enantiospecific interactions. Through a partial least squares regression (PLSR) a calibration line can be established for the mixing ratio of ternary aqueous D- and L-tryptophan solutions.