Separation of the non-volatile noble metals by reversed-phase extraction chromatography.
The procedure involves the use of tri-n-butyl phosphate (TBP) adsorbed by Porasil C and stepwise elution with sulphuric acid and hydrochloric acid. The distribution coefficients for the two systems (TBP and hydrochloric acid and TBP and sulphuric acid) and the elution characteristics were studied. A description is given of a procedure applicable to the analysis of prills obtained from the fire assay of platinum-bearing ores.
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.
Ion-exchange resins in non-aqueous solvents-II Sorption of P-nitroaniline and other weak bases in water-organic solvent mixtures.
Sorption of p-nitroaniline and several weak organic bases on macro- and microreticular hydrogen-form resins is reported. The solvents used in the study are mixtures of water and fourteen watermiscible organic solvents. The distribution coefficients change from a large value at pure organic solvent to a minimum value at 80% organic solvent-20% water, then increase again except for the basic solvents where no sorption takes place at high organic solvent concentration. It is suggested that in the vicinity of the minimum D a transition in sorption mechanism takes place. A similar behaviour is observed for several other weak organic bases. The sorption of p-nitroaniline in 80% organic solvent-20% water as a function of time is reported. Mesh size and percentage cross-linking are other variables considered.