Spectrophotometric procedure using rhodamine B for determination of submicrogram quantities of antimony in rocks

A spectrophotometric procedure using Rhodamine B is given for the determination of antimony in mineralized rocks after its separation as stibine. A study of the Rhodamine B reaction points to the importance of the order of addition of reagents in enhancing sensitivity and increasing the stability of the system. The tolerance of some 26 elements is established for the overall procedure. Although the limit of determination is approximately 0.5 ppm Sb in a 0.2-g sample, the procedure is intended primarily for screening samples containing more than 1 ppm Sb. In pure solutions 0.1 mug of antimony can be determined with a relative standard deviation of 25%. For >0.2 mug of antimony a relative standard deviation of 15% or less can be expected.