Electrochemiluminescence-based quantitation of classical clinical chemistry analytes

Electrochemiluminescence (ECL)-based assays are described for the quantitation of potentially any clinical analyte that can be linked to a beta-nicotinamide adenine cofactor-requiring or hydrogen peroxide-forming enzyme. Light was emitted when an appropriate voltage was applied to an electrode immersed in a solution containing the inorganic luminescent complex, ruthenium(II) tris(bipyridyl), and either NAD(P)H or H2O2. 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-depleting enzyme), cholesterol (H2O2-forming enzyme), and glucose-6-phosphate dehydrogenase (temporal measurement of catalytic NADPH formation). Satisfactory correlations were found between ECL and conventional spectrophotometric analyses. The wide assortment of formats used to quantitate clinical analytes indicates that many other similarly coupled analytes may also be quantitated by ECL.