AMPEROMETRIC GAS-PHASE SENSOR FOR THE DETERMINATION OF AMMONIA IN A SOLID-STATE CELL PREPARED BY A SOL-GEL PROCESS

An interdigitated microelectrode array (IME) that was coated with a fi lm of a vanadium oxide xerogel served as a solid-state cell in which a n anodic process in the presence of ammonia was promoted. The platinum indicator electrode array was modified with a film of mixed-valent ru thenium oxide with cyano cross-links, and the xerogel was loaded with KCl prior to use. Ammonia samples were quantified by injection of vapo rs into a gas cell that contained the modified and coated IME. Measure ments under potentiostatic conditions yield linear calibration curves over the range of 2 to 27 mu mol/ml.