Kjeldahl, Johan

Johan Kjeldahl first described his method for the determination of nitrogen in proteinaceous materials in 1883, when he was director of the Chemical Laboratory at the Carlsberg Foundation. At that time there was a pressing need for a more convenient and reliable procedure. Wanklyn s albuminoid ammonia method gave low and erratic results. Kjeldahl developed a succession of modifications that resulted in a technique very different from Wanklyn s - one which is still substantially the same today.65 66... 

The quantitative elemental analysis of organic compounds, perfected by Liebig for carbon and hydrogen in 1831 and by Dumas for nitrogen in 1834, has been described in Chapter 8. An alternative method for the determination of nitrogen was devised in 1883 by Johan Kjeldahl (1849-1900) in which the element is converted to ammonia, which is then determined by titration. The standard... 

Kjeldahl s method A method used for the determination of nitrogen in organic compounds. The nitrogenous substance is converted to ammonium sulfate by boiling with concentrated sulfuric acid (often with a catalyst such as CUSO4) in a specially designed long-necked Kjeldahl flask. The mixture is then made alkaline and the ammonia distilled off into standard acid for measurement by titration. It is named for the Danish chemist Johan Kjeldahl (1849-1900). 

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