Microdiffusion methods. Ammonia and urea using buffered absorbents (revised methods for ranges greater than 10μg. N)

Abstract

A revised microdiffusion method for ammonia and urea especially useful for clinical use is described. The ammonia already present or formed after the action of urease is absorbed in 2 ml. of a 0.5% boric acid reagent (or 1 ml. of 1%) containing 20% alc. and 1% of a mixed indicator soln. containing 0.033% bromcresol green, 0.066% methyl red in alc. The titration is carried out with N/50 HC1 from the horizontal burette, which is most convenient for microdiffusion detns., though a Bang burette may also be used. The question of the ideal absorbent for ammonia[long dash]using acidic titration subsequently[long dash]is discussed; as are further studies in the microdiffusion conditions relative to the alkali for use in the outer chamber, the fixative, the urease-phosphate mixture for the blood urea method etc.