Elution and spectrophotometric determination of gold after its separation from non-volatile platinum metals by column extraction chromatography.

Mixtures of gold(III) and iridium(IV) were separated by column extraction chromatography on silica treated with a tri-n-octylamine (TOA) salt. A mixture 2.25M in hydrochloric acid and 5M in nitric acid was used for elution of iridium. Gold was eluted together with the TOA salt by acetone, and after evaporation of the acetone, the TOA chloroaurate was dissolved in chloroform, converted into TOA bromoaurate and determined spectrophotometrically at 395 nm ( = 3.4 x 10(3) l.mole(-1) .cm(-1)). Beer's law was obeyed over the concentration range 5-67 ppm of gold. The method was found suitable for determination of gold after its separation from other metals by extraction chromatography on supports treated with liquid anion-exchangers.