Reaction rate ambiguities for perturbed spectroscopic data: Theory and implementation

Area of Science:

• Chemical Kinetics
• Spectroscopic Data Analysis
• Computational Chemistry

Background:

• Kinetic modeling and reaction system analysis are crucial for research and process design.
• Multivariate curve resolution (MCR) methods are powerful for spectral series analysis but suffer from inherent solution ambiguity.
• This ambiguity affects concentration profiles, spectra, and model parameters, influenced by the model and measurement errors.

Purpose of the Study:

• To develop a general theoretical and computational approach for analyzing solution ambiguity in kinetic models.
• To quantify uncertainties in MCR-derived parameters, concentration profiles, and spectra.
• To prevent erroneous conclusions regarding the uniqueness of MCR solutions.

Main Methods:

• A general theoretical framework for analyzing solution ambiguity in arbitrary kinetic models.
• A computational method to identify all model parameters yielding valid factorizations within error tolerances.
• Application as a post-processing step for MCR methods like MCR-ALS and ReactLab.

Main Results:

• Determination of concentration profile and spectra bands reflecting underlying ambiguity.
• Circumscription of the reliability of MCR solutions.
• Successful application to UV/Vis spectra of benzophenone relaxation and Raman spectra of aldehyde formation.

Conclusions:

• The developed method provides a robust way to assess and report MCR solution ambiguity.
• It enhances the reliability of kinetic modeling and spectral data interpretation.
• Freely accessible Matlab code is provided for ambiguity analysis and MCR hard-modeling.