The Analysis of Neutral Red and of the Pyronins

Abstract

Neutral red and the pyronins cannot be evaluated by means of reduction with titanous chloride, and market supplies of the stains contain nitrogenous dye intermediates which render other chemical methods of determining dye content unreliable. Data are furnished in the present paper which will enable the analyst to obtain reliable dye-content values with samples of these dyes by means of a convenient spectrophotometric technic.