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The Kjeldahl method or Kjeldahl digestion (Danish pronunciation: [ˈkʰelˌtɛˀl]) in analytical chemistry is a method for the quantitative determination of a sample's organic nitrogen plus ammonia/ammonium (NH 3 /NH 4 +). Without modification, other forms of inorganic nitrogen, for instance nitrate, are not included in this measurement.
Ammonia is used as a reagent to distinguish between the other two. While AgCl dissolves in ammonia (due to the formation of the complex ion [Ag(NH 3) 2] +), Hg 2 Cl 2 gives a black precipitate consisting of a mixture of chloro-mercuric amide and elemental mercury. Furthermore, AgCl is reduced to silver under light, which gives samples a violet ...
Fritz Haber, 1918. The Haber process, [1] also called the Haber–Bosch process, is the main industrial procedure for the production of ammonia. [2] [3] It converts atmospheric nitrogen (N 2) to ammonia (NH 3) by a reaction with hydrogen (H 2) using finely divided iron metal as a catalyst:
Ammonia electrolysis may require much less thermodynamic energy than water electrolysis (only 0.06 V in alkaline media). [23] Another option for recovering ammonia from wastewater is to use the mechanics of the ammonia-water thermal absorption cycle. [24] [25] Ammonia can thus be recovered either as a liquid or as ammonium hydroxide. The ...
Ammonia pollution is most commonly measured by its presence in the atmosphere. It has no automatic relay system as with other pollutant measurements such as carbon dioxide; therefore, ammonia samples must be collected through other methods including filter packs, fabric denuders, satellite imaging, and rainwater analysis.
The sampling method is often chosen to match the desired analysis method. Personal air-sampling pumps pull air into a charcoal tube or filter cassette for laboratory analysis. They are more accurate than other methods, but are bulkier to wear and require more specialized knowledge to use. [1]: 49, 60–61
Phenol in the Berthelot reagent can be replaced by a variety of phenolic reagents, the most common being sodium salicylate, which is significantly less toxic. [1] This has been used for blood urea nitrogen (BUN) determinations and commonly is used to determine water and soil total and ammonia-N. Replacement of phenol by 2-phenylphenol reduces interferences by a variety of soil and water ...
Gravimetric analysis describes a set of methods used in analytical chemistry for the quantitative determination of an analyte (the ion being analyzed) based on its mass. The principle of this type of analysis is that once an ion's mass has been determined as a unique compound, that known measurement can then be used to determine the same analyte's mass in a mixture, as long as the relative ...