a procedure for analyzing the content of nitrogenous compounds in urine, serum, or other specimens, usually to determine relatively large amounts of nitrogen (e.g., 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]
