Method Abstract #75 Ammonia by Direct Measure

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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.

Method Summary

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

Method Performance

*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.

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