Development of an on-line nitrogen monitoring system using Microdistillation Flow Analysis

Microdistillation Flow Analysis (MDFA) is a procedure to convert dissolved compounds into volatile compounds that can be transferred and isolated into another solution for determination by conductivity. Reagents are added to allow the analyte to form and accumulate in a collector solution prior to conductance detection. Control variables (sample and reagent flow rate, microstill air flow and temperature, and post-still collector volume) were optimised for the analysis. MDFA provided ammonia N data at a rate of 12 samples per hour with 2 % precision for samples containing ammonia or chloramine ranging from 0.03 to 0.6 mg/L ammonia N using a custom made prototype. Chloramine was also measured after in-stream reduction as ammonia N. The MDFA system may thus be useful as a tool in disinfection control and other environmental monitoring applications.