macro-Kjeldahl method

Pronunciation: kyel′dahl

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

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