ELECTROCHEMILUMINESCENCE-BASED QUANTITATION OF CLASSICAL CLINICAL-CHEMISTRY ANALYTES

Electrochemiluminescence (ECL)-based assays are described for the quan titation of potentially any clinical analyte that can be linked to a b eta-nicotinamide adenine cofactor-requiring or hydrogen peroxide-formi ng enzyme. Light was emitted when an appropriate voltage was applied t o an electrode immersed in a solution containing the inorganic lumines cent complex, ruthenium(II) tris(bipyridyl), and either NAD(P)H or H2O 2. The detection of H2O2 required oxalate as a coreactant. The amount of emitted light directly related to the concentration of NAD-(P)H or H2O2 Five classical clinical analytes were quantitated using different formats: glucose (coupled to both NADH- and H2O2-producing enzymes), ethanol (two NADH-producing enzymes in series), carbon dioxide (NADH-d epleting enzyme), cholesterol (H2O2-forming enzyme), and glucose-6-pho sphate dehydrogenase (temporal measurement of catalytic NADPH formatio n). Satisfactory correlations were found between ECL and conventional spectrophotometric analyses. The wide assortment of formats used to qu antitate clinical analytes indicates that many other similarly coupled analytes may also be quantitated by ECL.