MULTIVARIATE RESOLUTION OF RANK-DEFICIENT SPECTROPHOTOMETRIC DATA FROM FIRST-ORDER KINETIC DECOMPOSITION REACTIONS

The effect of a rank deficiency upon curve resolution in simple kineti c reaction-based systems is studied. Firstly, simulated rank-deficient spectrophotometric data of a mixture of two reagents, each one yieldi ng its own reaction product by a first-order kinetic reaction, are ana lysed. Four different situations are considered according to the diffe rences in the spectral responses of the reaction constituents and to t he differences in the rate constants between the two kinetic processes . A variation of the rate constant between runs for a certain kinetic process is also taken into account. Secondly, the resolution of a real rank-deficient data system, corresponding to the study of the pH-depe ndent decomposition of 1,2-naphthoquinone-4-sulphonate, is investigate d. All these studies were carried out using a multivariate curve resol ution method based on the alternating least squares optimization of th e kinetic and spectral profiles of the species present in the system. (C) 1998 John Wiley & Sons, Ltd.