Variable pH kinetics: An easy determination of pH-rate profile

The complete pH-rate profile of the hydrolysis reaction of aspirin, requiri ng many experiments in the past, was obtained by a single variable-paramete r kinetic experiment carried out by varying the hydrogen ion concentration. The experiment was carried out spectrophotometrically, reading automatical ly absorbance, pH, and temperature inside the reaction vessel. The results obtained by the fast processing of the kinetic profile are identical to tho se obtained under the same conditions but using traditional constant-pH kin etic runs. This method provides the possibility of reducing the amount of t ime and chemicals usually spent in collecting kinetic data in such mechanis tic studies by nearly two orders of magnitude. (C) 2001 Wiley-Liss, Inc.