SYSTEMATIC INTERPRETATION OF PH-DEGRADATION PROFILES - A CRITICAL-REVIEW

In this study we discuss the application of the general models for pH degradation profiles for specific acid, solvent and base catalysis, bo th in the absence and presence of ligands, and for the general acid an d base catalysis,that we have published recently, we also present a sy stematic step by step procedure for the interpretation of pH profiles, which we apply to a number of recent publications. To facilitate the comparison of the mathematical treatment of the data the model equatio ns reported in these studies have been transformed analogous to our eq uations. Many of these studies raise minor to serious objections. Thes e objectives vary from unjustified conclusions regarding the content o f specific reactions to the degradation, mathematical errors in the mo del equations, unjustified neglect of pK(a) values close to or within the pH range investigated? unjustified linearization of non linear rel ationships to the application of model equations with non integer expo nents without any theoretical foundation. Application of our model equ ations explains discrepancies in some of the original publications and offers acceptable alternatives to some rather stretched hypotheses. ( C) 1997 Elsevier Science B.V.