Use of reagent concentration gradient in the stationary phase for the separation of palladium(II) and rhodium(III) by countercurrent chromatography

The possibility of changing the composition of the stationary phase inside a rotating coiled column (RCC) in the course of a chromatographic process was discussed. The creation of a reagent concentration gradient in the stationary phase retained in a RCC significantly improves the efficiency of the separation of platinum-group elements by countercurrent chromatography. To separate palladium(II) and rhodium(III), a two-phase system containing methyltrialkylammonium chloride (MTAA) in toluene-hydrochloric acid was used.