Unified view of kinetic-based analytical methods with emphasis on ruggedness. A review

All analytical determinations can be grouped into two general categories, namely equilibrium-based and transient-based methods. This is an important grouping because most conventional approaches to transient-based methods are much less rugged than their equilibrium-based counterparts. As a result it is necessary to control variables within much narrower tolerances for transient-based methods than equilibrium-based methods to obtain similar degrees of reliability. This paper reviews measurement and data-processing methods developed to reduce effects of variables on transient-based methods, with emphasis on a general approach that is applicable to a wide variety of methodologies. The approach emphasized is identified as a pseudo-equilibrium method. In this method, transient data are used to compute signals that would be measured if all processes that affect the measurement could be monitored to equilibrium. Results included show that the pseudo-equilibrium method is applicable to the three most common types of responses from the transient phases of chemical and physico-chemical processes. Data included show 10- to 100-fold improvements in ruggedness relative to conventional measurement and data-processing options.