Evaluation of alternate coupling reagents to replace alpha-naphthyl amine for the detection of nitrate reduction.

Four naphthyl compounds, N,N,dimethyl-1-naphthylamine, N-1-naphthyl-ethylene-diamine dihydrochloride, 8-amino-1-naphthol-5-sulphonic acid, and 1-dimethylamino naphthalene-5-sulphonic acid, were evaluated as replacements for alpha-naphthyl amine in the bacteriological nitrate reduction test. These compounds were observed for their ability to detect standardized nitrite concentrations and nitrate reduction in eight bacterial cultures. The results indicated both N,N,dimethyl-1-naphthylamine and N-1-naphthyl-ethylene-diamine dihydrochloride, at concentrations of 0.035 M, were satisfactory alternatives. The working concentration of the latter might be reduced, as indicated by the results of sensitivity tests.