Comparison of simultaneous biexponential and compartmental analyses of fluorescence decay surfaces of intermolecular two-state excited-state processes

The performances of a simultaneous biexponential analysis and a global compartmental analysis of decay traces due to concentration-dependent two-state excited-state processes are compared. Using computer-generated fluorescence decay surfaces, it is shown that the global compartmental analysis estimates the rate constants with high accuracy, resulting in reliable decay time values. The standard global biexponential analysis fails to give accurate estimates of the short decay time when decay traces are combined if the pre-exponential factor associated with the short decay time is small, and when the pre-exponentials in the various decay traces are not substantially different. The superior parameter recovery by global compartmental analysis originates from the combination in a single analysis of all decay traces, allowing the rate constants to be linked over all concentrations. In contrast, only decays at the same concentration can be combined in the global biexponential analysis because the decay times are concentration-dependent.