Fast grey ra as a new colorimetric reagent for the microdetermination of bismuth

Fast Grey RA dye has proved to be a sensitive colorimetric reagent for microdetermination of bismuth. By its aid it is possible to determine with precision concentrations between 0.1 and 1p.p.m. in the presence of some other cations and anions, with a sensitive photometer or a Beckman spectro-photometer at a wavelength of 570 mμ. Among the interfering elements are cations of Cu, Zr, Ni, Cd,V and ferric iron. The latter element however, can be masked, to a great extent, by reduction with ascorbic acid.