Extraction of platinum with Astrafloxin FF from aqueous-organic solutions: Separative extraction-spectrophotometric determination of platinum(II) and platinum(IV) species

The optimum conditions of the extraction of the ion associates of platinum with the thiocyanate ions and the polymethine basic dye Astrafloxin FF by aromatic hydrocarbons and acetic acid esters from aqueous and aqueous-organic solutions were studied. The introduction of water-soluble donor-active solvents (hexamethylphosphoric triamide, N,N-diethylacetamide, N,N-dimethylformamide, and N,N-diethylformamide) leads to a considerable increase in the extraction of the ion associates of platinum and the simultaneous suppression of the extraction of the simple dye salt. The molar absorption coefficients of the extracts of ion associates are as high as (8.1?C13.3) × 10⁴. 84?C96% platinum is extracted in the form of ion associates by a single extraction. The conversion of platinum into ion associates makes it possible to separate platinum from many elements, including Cu, Cd, Ni, Co, Cr, Pb, In, Ag, Pd, Ir, Rh, and Ru, by extraction. In this case, platinum(II) is extracted in the form of ion associates under standard conditions, whereas platinum(IV) is extracted only after the preliminary thermal treatment of the test sample. A new procedure was developed for the extraction-spectrophotometric determination of the trace amounts of platinum(II) and platinum(IV), in particular, in their mixtures.