Continuous water quality monitoring of ammonia is becoming increasingly important for plant operations and process control. Unfortunately, on-line ammonia monitors are generally very expensive, complex, and labor intensive instruments. Most are automated versions of ammonia selective ion electrodes methods better suited to laboratory measurements. Others are automated colorimetric devices or instrumental methods that are difficult to justify on a cost basis.ATI has developed a completely new approach to on-line monitoring of ammonia that is far less expensive and much simpler than conventional monitoring equipment. The Q46N Dissolved Ammonia Monitor uses reaction chemistry that converts ammonia in solution to a stable monochloramine compound equivalent in concentration to the original ammonia level. The chloramine concentration is then measured with a unique amperometric sensor that responds linearly to chloramines while eliminating interference from excess free chlorine in solution.