COLORIMETRIC DETERMINATION OF BLOOD AND BRAIN AMMONIA IN-VITRO BY A MODIFIED METHOD

A modified method that incorporates Conway microdiffusion to trap ammo nia and indophenol reaction for colorimetric determination of microqua ntities of free ammonia in blood and brain samples is described in thi s paper. By this method, 60-70% of ammonia could be recovered from a k nown ammonium chloride solution. Blood and brain of adult female rats (control) measured 1.41 +/- 0.24 mu g/ml and 5.47 +/- 0.61 mu g/g, of ammonia respectively. The method was tested by dertermining blood and brain ammonia concentrations 15 min after intraperitoneal injection of ammonium chloride (100 mg/kg and 200 mg/kg) in female rats. The metho d is simple and sensitive and is useful for determination of microquan tities of ammonia in blood and brain samples in experimental animals.