Ammonia by Direct Measure
Method Abstract #75
Scope and Application
This method conforms to Standard Methods 4500-NH3 D and ASTM D 1426 (B). It determines the concentration of ammonia in a water sample.
The concentration of ammonia is determined by an ammonia ion selective electrode. After calibrating with known standards, the sample’s response can be compared to the calibration curve and a concentration determined. Both the standards and the samples are pre-treated with sodium hydroxide to convert all the ammonium ions into ammonia.
Sample Calibration Curve
*Data for this measuring range was obtained using laboratory prepared standards formulated from ammonium chloride. The measuring range may be increased by using auto-dilution.
**The Method Detection Limit (MDL) was determined based on data obtaining a coefficient of variance better than 30%. Results may differ depending on laboratory practices and sample matrix.
RSD values are better than those specified in Standards Methods.