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

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Cheminformatics

Background:

• Probing intermolecular interactions between enantiomers is crucial in chemistry and pharmaceutical sciences.
• Raman spectroscopy offers sensitive and selective optical measurements.
• Multivariate data analysis enhances the interpretation of complex spectral data.

Purpose of the Study:

• To demonstrate the optical differentiation of aqueous d- and l-tryptophan enantiomers using Raman spectroscopy.
• To identify key functional groups involved in enantiospecific interactions via PCA.
• To establish a quantitative method for determining the mixing ratio of tryptophan enantiomers.

Main Methods:

• Utilized Raman spectroscopy for spectral acquisition of aqueous d- and l-tryptophan solutions.
• Applied principal component analysis (PCA) to differentiate enantiomeric spectral data.
• Employed partial least squares regression (PLSR) for quantitative analysis of enantiomer mixtures.

Main Results:

• Successfully achieved optical differentiation of d- and l-tryptophan enantiomers in aqueous solutions.
• PCA loadings highlighted functional groups critical for enantiospecific interactions.
• Established a reliable calibration line using PLSR for predicting mixing ratios.

Conclusions:

• Raman spectroscopy coupled with PCA is a powerful technique for analyzing enantiomers.
• The study provides a method for identifying and quantifying chiral interactions in solution.
• This approach has potential applications in chiral analysis and quality control.