FLOW-THROUGH PH-ISFET AS DETECTOR IN THE DETERMINATION OF AMMONIA

A simple flow-injection metod for the determination of ammonium ions in water, based on a flow-through pH-ISFET, is described. Ammonium is converted to ammonia, which diffuses through a microporous hydrophic membrane into an ammonium chloride recipient stream, forming a pH buffer which is monitored by the semiconductor detector. The linear working range extends from 0.1 to 10 mmol l-1 with a relative standard deviation of ca. 1% at the 0.7 mmol l-1 level. © 1990.