Second-order globalisation for the determination of activation parameters in kinetics

First order global analysis consists of linking common parameters across series of measurements, e.g., reaction kinetics measured at different wavelengths where the rate constants are the same for all kinetic traces at individual wavelengths. This approach is taken a step further in second order globalisation. A series of measurements is linked together by a new superimposed model which encompasses the individual measurements. The mathematics for the non-linear least-squares fit of the global parameters is presented. Two modes are possible depending on whether the linear parameters (absorption spectra) are constant or changing across the series. Factor analysis is incorporated for multivariate measurements. The procedures are exemplified with applications of activation analysis in chemical kinetics. Global analysis of complete temperature and pressure dependences results directly in the activation parameters of interest, i.e., activation enthalpies, entropies and volumes. Due to a significant decrease in the number of parameters to be fitted, the robustness is considerably improved.