Rapid Determination of Ammonia in a Perchloric Acid Supernate from Blood, by Use of an Ammonia-Specific Electrode

Abstract

Abstract A simple, rapid method was developed for accurate determination of ammonia in whole blood. Blood proteins were precipitated with perchloric acid (8 g/dl) and the free ammonia liberated in the supernate on alkalinization was measured directly with an ammonia-specific electrode after adjusting the sample temperature to 25 °C. Some variables affecting precision, accuracy, and electrode performance were studied. Sensitivity, specificity, and interferences are discussed. The tentative normal range is 28 ± 14 µg of ammonia nitrogen per deciliter. The coefficient of variation was 4.8% in the "normal," 3.6% in the "abnormal" range. Abnormal values were correlated with clinical status. Recoveries averaged 99.3%. Correlation with an established ion-exchange method for plasma ammonia was 0.994. Total time required for a complete assay is 15 min.