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General Spectroscopy - Measuring ammonia (NH3) using ICP-OES

 
We have a requirement for the analysis of ammonia content in solid calcium chloride, and have an ICP-OES in our lab. Do you know if it is possible to determine the ammonia content with this equipment? A literature search indicated that the reaction of ammonia with hypochlorite and salicylate, catalyzed by nitroferricyanide, produces a blue dye that can be measured spectrophotometrically at 670 nm.
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An ICP is not the ideal choice for measuring ammonia, as the plasma will not only destroy the ammonia compound, by contamination by atmospheric nitrogen could bias the results. The salicylate method referenced is for spectrophotometry, which uses the adsorption of light to perform an analytical measurement (using a spectrophotometer). An ICP is not a spectrophotometer, as it is based upon the principle of measuring the light emitted by a sample, and so the method and instrument are not directly compatible.  If you need only to determine the ammonia content to with 10-15%, then a visual comparison using the salicylate method may be sufficient, whereby you simply compare (by eye) the color intensity of the sample to a set of ammonia standards. If a greater degree of analytical certainty is required, then Kjeldahl or ion chromatography methods may be more appropriate.
Posted: 09/04/18 21:32:14

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