Calculation of band boundaries of feasible solutions obtained by Multivariate Curve Resolution–Alternating Least Squares of multiple runs of a reaction monitored by NIR spectroscopy

This study describes a method for calculating the band boundaries of feasible solutions for spectra and concentration profiles obtained by Multivariate Curve Resolution–Alternating Least Squares (MCR–ALS) analysis of a spectroscopic NIR data set. The data set is obtained by monitoring in situ the model reaction between phenyl glycidyl ether (PGE) and aniline. As this system happened to be rank-deficient, the resolution strategy used matrix augmentation. The calculation of band boundaries of feasible solutions is extended here to the simultaneous analysis of multiple data matrices. The boundaries were obtained by a non-linear constrained non-linear optimisation. The influence that the number and type of data matrices in the simultaneous analysis have on the amplitude of band boundaries is also discussed.