A rapid spectrophotometric method for the determination of carbon monoxide in ambient air

A sensitive spectrophotometric method for the determination of carbon monoxide is described, based on the reduction of palladium(II) by carbon monoxide. The resulting elemental palladium is reacted with iodate in acidic medium in the presence of chloride, to produce an ICl(-)(n) species that is readily extracted as an ion-pair with Pyronine-G into benzene. Measurement of the absorbance of the extract at 535 nm permits the determination of carbon monoxide down to 1 mul/l. in air. The effect of interfering gases is discussed. The method is suitable for determination of carbon monoxide in motor vehicle exhaust gases and ambient air.