An approach mixing the qualities of hard- and soft-modelling methods has been proposed to analyse kinetic data monitored spectrometrically. The investigation of the kinetics of a chemical reaction serves two purposes. The first goal is the determination of the mechanism of a reaction and the other is the determination of the rate constant(s) of the reaction. In this work, we present the results of spectrophotometric studies of charge-transfer interactions between lidocaine, procaine and venlafaxine as electron donors and iodine as electron acceptor in chloroform, dichloromethane (DCM) and 1,2-dichloroethane (DCE) solutions at 25 ◦C. Using soft-modelling approaches, evolving factor analysis (EFA) and multivariate curve resolution-alternating least squares (MCR-ALS), without the previous information of the system the number of species present in the system and their behavior has been identified. The mechanism of the reaction was determined from the two-way kinetic-spectral data using hard-modelling approach. The performances of the new methods have been evaluated by applying them to analysis of simulated and experimental data. The influence of solvent properties on the kinetics of the resulting charge-transfer complexes are discussed. Formation of I3- in solution was related to the slow transformation of the initially outer complex to an inner complex and then fast reaction of the inner complex with iodine. The rate constants of the resulting complex in three solvents was also found to vary in the order of 1,2-DCE >DCM> CHCl3.
