Determination of oxygen concentrations by luminescence quenching of a polymer-immobilized transition-metal complex

Oxygen quenching of the luminescence of the tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) perchlorate immobilized in a silicone rubber is shown to be an accurate and precise method for measuring oxygen concentrations in solutions and in the gas phase. Quenching can be quantitated by either lifetime or intensity quenching measurements. Aqueous strong acids, bases, complexing agents, oxidants, and reductants do not penetrate the hydrophobic polymer and, therefore, do not affect the response. Gaseous interferents, such as H/sub 2/S, anesthetic gases (e.g., N/sub 2/O, halothane), and fluorocarbons do not affect the response. Chlorine and especially SO/sub 2/ are strong, but fully reversible, interferents. A system was developed with a response time of less than 0.2 s, which is adequate for the monitoring of breathing subjects.