Kjeldahlkväve

Kjeldahlkväve refers to the nitrogen content determined by the Kjeldahl method. This analytical procedure is widely used to measure the total nitrogen content in organic compounds and, by extension, in various samples such as food, feed, soil, and water. The method involves the digestion of the sample with concentrated sulfuric acid, which converts organic nitrogen to ammonium sulfate. A strong base, typically sodium hydroxide, is then added to liberate ammonia gas, which is subsequently distilled and collected in an acidic solution. The amount of ammonia, and therefore the nitrogen content, is then quantified, usually by titration. This value, when multiplied by a conversion factor, can provide an estimate of the protein content, as protein is a major source of nitrogen in many biological materials. The Kjeldahl method is considered a reference method for protein determination due to its reliability and widespread acceptance. However, it does not account for nitrogen present in non-protein forms, such as nitrates or nitrites, meaning Kjeldahlkväve is not a direct measure of total nitrogen in all circumstances.