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a procedure for analyzing the content of nitrogenous compounds in urine, serum, or other specimens, usually to determine relatively large amounts of nitrogen (for example, 20-100 mg); the specimen is treated with a digestion mixture (copper sulfate and sulfuric acid), heated thoroughly, and made alkaline with a solution of sodium hydroxide; ammonia is then distilled from the mixture, trapped in a boric acid-indicator solution, and titrated with standard hydrochloric or sulfuric acid.
[Johan G. C. Kjeldahl]
Kjeldahl,Johan G.C., Danish chemist, 1849-1900.
Kjeldahl apparatus - an apparatus used in nitrogen analysis.
macro-Kjeldahl method - a procedure for analyzing the content of nitrogenous compounds in urine, serum, or other specimens.
micro-Kjeldahl method - a modification of the macro-Kjeldahl method designed for the analysis of nitrogenous compounds in relatively small quantities.