Combinations of reagents are described for the catalyzed indophenol reaction for the determination of ammonia, which produces a stable blue color. The procedure is adapted to the determination of urea after hydrolysis with urease.

A modification of enzymatic technics for measurement of concentrations of lactate and pyruvate in blood is described. A common protein-free filtrate is prepared by adding blood directly to cold 5% metaphosphoric acid. Theoretical yields are obtained. Recoveries for lactate range from 98 to 102% and for pyruvate from 97 to 104%. Assay of both lactate and pyruvate is simplified and has a high order of reliability. Since both analyses are completed within a period of 20 mm., the method is especially valuable in the emergent clinical situation in which measurements of lactate and pyruvate are obtained for assessment of the severity of shock and other forms of cardiorespiratory failure.

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