Determination of ammonia in saliva using indophenol, an ammonium electrode and an enzymatic method: a comparative investigation.

Three methods for determination of ammonia in saliva are reported. The indophenol method on diluted saliva has the best precision (coefficient of variation 0.8%) and the lowest reagent cost. The ammonium electrode method is the quickest, but it requires simultaneous determination of the potassium content of the specimen. The enzymatic method give the same result as the electrode method, but is more expensive. Deproteinisation proved not to be necessary. In one hour 10, 20 or 40 determinations can be performed with the enzymatic, indophenol- or the electrode method, respectively.