Two chemical approaches for the production of stable solutions of tris(2,2'-bipyridyl)ruthenium(III) for analytical chemiluminescence

Two methods for the chemical generation of the chemiluminescence reagent Ru(bipy)3+3 are presented, both of which used lead dioxide as the oxidant with various concentrations of sulphuric acid. The temporal stability of several different Ru(bipy)3+3 solutions was investigated, with significant extension to their analytically useful lifetime being afforded by simply increasing the acid concentration. Alternatively, recirculation of the reagent through a glass filter assembly containing lead dioxide also extended the stability of Ru(bipy)3+3 under mildly acidic conditions. A series of flow injection analysis experiments, using codeine to generate chemiluminescence, were performed to quantify the stability of the various reagents with the useful lifetimes ranging from several hours to more than a week, depending on the acid concentration. The change in concentration of Ru(bipy)3+3 versus time was measured spectrophotometrically (at λ(max), 674nm) in order to evaluate the kinetics of the reagent degradation process and its effects on chemiluminescence response for codeine. These preliminary results are presented as a simple and robust alternative to electrochemical generation for those applications where medium to long term reagent stability is essential, such as in liquid chromatography and process analysis. Copyright (C) 1999 Elsevier Science B.V.