A microassay for blood ammonia has been developed. After dilution, blood is dialyzed by a continuous flow procedure, and the ammonium ions in the dialysate are assayed colorimetrically by the hypochlorite-phenol Berthelot reaction. Concentrations from 1 to 400 μπιοΐ/l NH^ can be measured in a 50 μΐ whole blood sample. Using slight modifications, concentrations up to 800 μπιοΐ/ΐ NHj can be determined. The precision, accuracy, sensitivity, and specificity of the method have been studied. In man, the usual values (mean ± 2 SD) found are 27.4 ± 10.2 μτηοΐ/ΐ NH^ in arterial blood, 20.9 ± 9.8 μτηοΐ/ΐ in venous blood. The usual values in rats and mice are very close to those given for man. Blutammoniak-Bestimmung mit einer automatischen MikromethodeZusammenfassung: Zur Bestimmung des Blutammoniaks wurde eine Mikromethode entwickelt. Das Blut wird nach Verd nnung kontinuierlich flie end dialysiert. Die Ammoniumionen werden im Dialysat kolorimetrisch mittels der Hypochlorit-Phenol Reaktion von Berthelot bestimmt. Ein Gehalt von l bis 400 μπιοΐ/ΐ NHj kann in 50 μΐ Vollblut bestimmt werden. Geringe methodologische Ab nderungen erlauben es, Konzentrationen bis zu 800 μπιοΐ/ΐ NHj zu messen. Pr zision, Genauigkeit, Empfindlichkeit und Spezifizit t der Methode werden untersucht. Beim Menschen sind mit dieser Methode die blichen Befunde (Mittelwert ± 2 SD) 27,4 ± 10,2 μπιοΐ/ΐ NHj im arteriellen Blut und 20,9 ± 9,8 μπιοΙ/1 im ven sen Blut zu erheben. Bei Ratten und M usen finden sich hnliche Werte.

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Blood glutamine is hydrolyzed by glutaminase; the resulting ammonia is dialyzed out and measured by use of a continuous-flow colorimetric microassay. Concentrations in the range of 10 to 1300 micromol of glutamine per liter can be determined in a 40-microliter sample. With slight modifications, higher concentrations, up to 5 mmol/liter, can be measured. Assay conditions and the qualities of the microtechnique were made optimal. Usual values obtained with this method for arterial and venous blood in man are, respectively, 443 +/- 140 and 466 +/- 142 micromol/liter (mean +/- 2 SD). Corresponding values for rats are 320 +/- 92 and 340 +/- 108 micromol/liter. Fasting causes a decreased blood glutamine.

Plasma L-alanine is deaminated by bacterial alanine-dehydrogenase; the resulting ammonia is dialyzed out and measured by use of a continuous flow phenol-hypochlorite colorimetric microassay. Concentrations in the range of 10 -1,000 μmol alanine/l can be determined in a 50-μl sample. The optimal conditions for the assay are specified. Study of the analytical qualities of the technique shows high specificity, good reproducibility, and a detection limit of 6 μmol/l. Usual values in human plasma from arterial or venous blood are respectively 296 ± 166 and 376 ± 214 ;umol alanine/1 (x ± 2 SD). The usual values in rats are close to those found in man.