THE MAGNITUDE OF THE ERROR DUE TO AMMONIA AND ITS SALTS IN THE VAN SLYKE AMINO NITROGEN PROCEDURE AS COMMONLY APPLIED IN STUDIES OF BACTERIAL METABOLISM

Abstract

A quantitative study, from the physico-chemical point of view, has been made of the decomposition of ammonium salts in the Van Slyke procedure. The reaction is of the first order. This leads to the conclusion that the relative amounts of ammonia N evolved are independent of the initial concentrations of the ammonium salts. This was demonstrated experimentally over the range of 100-500 mgm. of ammonia N per 100 cc. The reaction has a temperature coefficient of 3.0 from 20 to 30[degree]C. Curves are given showing the percentages of total ammonia N evolved at various temperatures with 1 and 2 cc. samples in the micro apparatus with 3 minute shaking. The possibility of applying the data to the calculation of corrections for the ammonia present in cultures is briefly discussed. The results adequately account for the failure of some investigators to obtain satisfactory checks. A table is given of 10 consecutive analyses on ammonia-free material showing that it is possible to obtain good checks.