Flow Injection Determination of Ammonia-N Using Polymer Membrane Electrode-based Gas Sensing System

Abstract
A new potentiometric gas sensing concept is used in conjunction with a flow injection technique to rapidly determine ammonia-nitrogen in the 10−5 to 10−2 mol/L range. The system designed utilizes a novel tubular flow-through PVC-nonactin membrane electrode to detect ammonium ions formed in a recipient buffer stream as the sample flows through a gas dialysis unit. At least 30 samples/h can be determined with good precision ( ± 7%) for samples  10−5 mol/L in ammonia-N. Preliminary data concerning the analytical application of this system for blood ammonia-N measurements is presented. A novel gas dialysis method for removing ammonia from blood samples is also described.