An exploratory analysis of the electron donor–acceptor complex formation between risperidone and iodine by principal component analysis, soft- and second-order hard-modelling approaches

An exploratory analysis of the electron donor–acceptor complex formation between risperidone and iodine has been done by a strategy equipped with rank augmentation, principal component analysis (PCA) and soft-modelling approach, orthogonal projection approach (OPA), followed by second-order hard-modelling in two non-aqueous solvents with different polarities. From the results of PCA and OPA, the correct number of chemical components and the reactions were identified. In all cases the collected data were found to be rank deficient. In the case of electron donor–acceptor complex formation in acetonitrile, a single second-order reaction and for the process in chloroform, a consecutive two-step reaction was identified. Iodine participates in the second-order rate determining steps in the two solvents. Rank deficiency of the processes was broken through second-order global analysis of the multiple processes with different initial concentrations. Second-order global hard-modelling of the non-linear parameters (rate constants) as well as linear parameters (absorptivities) based on the model derived resulted in well-defined parameters with small standard deviations. Well-resolution of the parameters and the profiles indicated that the models were properly selected.