Application of a novel resolution approach combining soft- and hard-modelling features to investigate temperature-dependent kinetic processes

A new resolution method based on the combination of hard- and soft-modelling is applied to the analytical study of spectrometrically monitored kinetic processes. This method results from the modification of the iterative soft-modelling multivariate curve resolution-alternating least-squares method (MCR-ALS) by the inclusion of a new hard constraint that forces some or all the concentration profiles to fulfil a kinetic model. In this way, strengths of both soft- and hard-modelling data analysis methods are combined and limitations linked to the application of only one of these pure approaches are overcome. The new method is applied to a real example of cyclometallation reaction. This is a challenging case where the extent of the process changes with temperature and the spectra of the different species formed do not differ extremely from each other. Besides, due to the lability of the initial reagent, the nature and the concentrations of all the reacting components present at the beginning of the process are not always known. The example presented is representative of many other complex kinetic problems, which could not be solved by the use of traditional methods based exclusively on the straightforward fitting of kinetic models. (C) 2001 Elsevier Science BY. All rights reserved.