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Uncatalyzed Kinetic Determinations

Kinetic Determinations

  1. Michael A. Koupparis

Published Online: 15 SEP 2006

DOI: 10.1002/9780470027318.a5709

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Koupparis, M. A. 2006. Uncatalyzed Kinetic Determinations. Encyclopedia of Analytical Chemistry. .

Author Information

  1. University of Athens, Greece

Publication History

  1. Published Online: 15 SEP 2006

Abstract

Analytical procedures in which the measurement step (chemical, physical or physicochemical) is influenced by a transient (kinetic) process, can strictly be classified as kinetic method. Thus, the majority of modern analytical methods (continuous-flow, time-resolved fluorimetric and chromatographic methods, among others) are kinetic in nature. Nevertheless, the term “kinetic method”, for historical reasons, is incorrectly limited to methods based on direct or indirect measurements of the rate of a chemical reaction, which should be classified as “reaction-rate methods”. Analytical methods based on signal measurements made under dynamic conditions compete in efficiency with static and equilibrium measurements. The growing development of kinetic methods is due to the need for quantification of microamounts of substances, increasing knowledge of reaction mechanisms, and breakthroughs in instrumentation and data handling and interpretation. The most popular classification of kinetic methods of analysis is based on the chemistry of reactions employed and distinguishes between catalytic (nonenzymatic, enzymatic and electrochemical), and noncatalytic methods. The latter are further categorized into those used to determine a single species or several components in mixtures (differential reaction-rate methods). This article deals with kinetic methods for the determination of single noncatalytic species. Although the majority of kinetic-based determinations depend on catalytic systems, some analytical applications using the rate of uncatalyzed reactions are of analytical interest, mainly those involving organic chemical species. Advances in instrumentation: (1) improved signal detection, (2) resolving of problems arising from time measurements especially in fast processes, and (3) availability of automated mixing devices and data processing (error-compensated methods, curve-fitting and predictive approaches) establish noncatalytic methods as powerful alternatives to equilibrium methods. The main field of application of noncatalytic reactions is organic analysis, unlike catalytic reactions where a metal ion usually acts as the catalyst.