A new electrogenerated chemiluminescence (ECL) reaction which utilizes tripropyl amine and Ru(bpy)32 § is presented. The mechanism of light generation appears general enough to include a range of amines and luminophores. An oxidative-reduction mechanism is proposed. Upon electrochemical oxidation of both the luminophore and amine, a strong emission is observed. Voltammetric analysis reveals the potential for greatest light emission at the tripropyl amine oxidation. The e~ission is from the excited state of Ru(bpy)32 § An electron transfer reaction from the deprotonated tripropyl amine radical and Ru(bpy)3 ~ § is the central reaction for excited state production. An estimate of the ECL efficiency cannot be made, due to the complex nature of the reaction.

Electrochemical charge collection techniques were used to study the effects of platinization and reduction on the electron-transfer (et) kinetics and energetics of illuminated tungsten oxide colloids. From the mediated charge collection experiments, the quasi-Fermi level for electrons, «£>*, was found to be +0.33 V vs. NHE (pH 0) for W03 and shifted to +0.21 V for the reduced (H^W03) and platinized (Pt/W03) tungsten oxides. The platinization of W03 also caused it to be irreversibly reduced. Silica particles coated with a monolayer of W03 displayed an nEF* which was 170 mV negative of that for W03. The photocurrent transients for direct et to a collector electrode were potential dependent and were used to measure k°, the standard heterogeneous rate constant for et, by using a previous treatment derived for iron oxides. The reduction of W03 decreased k°, while platinization slightly increased it.

Electrochemiluminescence (ECL) has been developed as a highly sensitive process in which reactive species are generated from stable precursors (i.e., the ECL-active label) at the surface of an electrode. This new technology has many distinct advantages over other detection systems: no radioisotopes are used; detection limits for label are extremely low (200 fmol/L); the dynamic range for label quantification extends over six orders of magnitude; the labels are extremely stable compared with those of most other chemiluminescent systems; the labels, small molecules (approximately 1000 Da), can be used to label haptens or large molecules, and multiple labels can be coupled to proteins or oligonucleotides without affecting immunoreactivity, solubility, or ability to hybridize; because the chemiluminescence is initiated electrochemically, selectivity of bound and unbound fractions can be based on the ability of labeled species to access the electrode surface, so that both separation and nonseparation assays can be set up; and measurement is simple and rapid, requiring only a few seconds. We illustrate ECL in nonseparation immunoassays for digoxin and thyrotropin and in separation immunoassays for carcinoembryonic antigen and alpha-fetoprotein. The application of ECL for detection of polymerase chain reaction products is described and exemplified by quantifying the HIV1 gag gene.

Electrogenerated chemiluminescence (ECL) is the process in which electrogenerated species undergo electron transfer reactions to form excited states that emit light. Many molecules have the potential to produce ECL, however Ru(bpy) 3 2+ (bpy = 2,2′‐bipyridine) is the most common emitter used for analytical applications. Application of a voltage to an electrode in the presence of an emitter induces light production and allows for the detection of the emitter at very low concentrations. Advantages over other analytical methods include low backgrounds, precise spatial and temporal control over the emission, and the possibility of signal amplification. Commercial systems exist that use ECL to detect numerous clinically relevant analytes with high sensitivity using a variety of assay formats.

Electrochemiluminescence (ECL)-based assays are described for the quantitation of potentially any clinical analyte that can be linked to a β-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 H 2 O 2 . The detection of H 2 O 2 required oxalate as a coreactant. The amount of emitted light directly related to the concentration of NAD-(P)H or H 2 O 2 . Five classical clinical analytes were quantitated using different formats: glucose (coupled to both NADH-and H 2 O 2 -producing enzymes), ethanol (two NADH-producing enzymes in series), carbon dioxide (NADH-depleting enzyme), cholesterol (H 2 O 2 -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.