A multi-pumping flow system for chemiluminescent determination of ammonium in natural waters

A multi-pumping flow system with improved mixing conditions is proposed for chemiluminescent determination of ammonium in natural waters. The system includes a gas-diffusion unit, a Y-connector made of sintered glass particles (100-200 mesh), and a chemiluminometric detector. System configuration, flow rates, reagent concentrations, pH, and reactor lengths were optimized. The analytical curve is linear from 0.3 to 5.0 mg L-1 N-NH4, and the detection limit is estimated as 0.02 mg L-1 at the 99.7% confidence level. The system handles about 50 samples per hour, requires 3.1 µg of active chlorine and 0.11 mg of luminol per determination, and yields precise results (RSD<1.2%, n = 10) in agreement with those obtained by the spectrophotometric indophenol blue method.