Hygienic-chemical Studies on Public Water. (V). : Improvement on the Determination Methods of Pitrate in the Presence of Nitrite-nitrogen.

Abstract

The factors for determining NO3--N in the presence of NO2--N were investigated. Two methods, i.e. the total value method reported by Yui and the aniline method, were taken up. The total value method was satisfactory, in which NO3--N was reduced to NO2--N in the presence of NO2--N as described by Lambert-Zitomer and as the result the value of the concentration of total NO2--N (the total value of NO3--N and NO2--N) was obtained, then the concentration of NO3--N was calculated by subtracting the value of the concentration of NO2--N in the sample solution from the value of the concentration of total NO2--N. Under the usual condition the second method, the aniline method, showed the considerable dispersion in the values of NO3--N obtained with the same sample solution. But the aniline method has been improved by the following modification of procedures. 1) On the diazotization of aniline, potasium bromide was added. 2) For the reduction of NO3--N to NO2--N, the condition reported by Lambert-Zitomer was used. 3) On coupling of aniline diazonium salt, α-naphthol was adopted as a coupling agent in the alkaline solution. (Received June 11, 1964)