Continuous flow determination of low concentrations of ammonium ions using a gas dialysis concentrator and a gas electrode detector system

Abstract

A simple concentrator based on a microporous poly(tetrafluoroethylene) membrane and polymer nets has been developed and combined with an ammonia-selective gas electrode to construct a continuous flow determination system for low concentrations of ammonium ions in water. The gas dialysis concentrator continuously gives about a ten-fold increase in the concentration of ammonium ions and extends the linear response limit of an ammonia-selective gas electrode from 30 to about 3 µg l^–1. The system was applied to the determination of residual concentrations of ammonium ions in water purified by distillation and/or de-ionisation and to natural water analysis.