The automatic amperometric and potentiometric microtitration of pharmaceutically important sulfanilamide derivatives by diazotization with nitrite

The automatic amperometric and potentiometric microtitration of pharmaceutically important sulfanilamide derivatives by diazotization with nitrite is described. Optimal conditions for diazotization and amperometric indication are discussed. A new cathodic amperometric indication of nitrite in M hydrochloric acid-25% ($\text{w}\text{v}$) of potassium bromide medium is proposed; the electrode processes involved are interpreted on the basis of current-potential curves. The effects of the hydrochloric acid and bromide concentrations, and of temperature on the limiting current are described. Sulfamethazine, sulfadimethoxine, sulfamethoxypyridazine and sulfamethoxypyrazine were titrated amperometrically in the range 10^?3–10^?6 M. Potentiometric titrations of these sulfanilamides were possible in the range 10^?3–10^?4 M.