MECHANISM OF THE RETENTION OF ION ASSOCIATES OF HETEROPOLY ACIDS WITHTRIOCTYLAMINE ON A NITRILE PHASE

The separation and the mechanism of retention of ion associates of alp ha-isomers of molybdic and tungstic heteropoly acids of phosphorus(V), silicon(IV), and germanium(IV) with trioctylamine on a column (80 x 3 mm) packed with Diasorb-130-CN (8 mu m) were studied in a flow of chl oroform-tetrahydrofuran-trioctylamine and chloroform-n-butanol-triocty lamine mixtures with spectrophotometric detection at 320 nm. It is dem onstrated that the adsorption of all the studied ion associates procee ds through the displacement of one tetrahydrofuran molecule from the s urface of the stationary phase and without the displacement of triocty lamine molecules. Conditions for the separation of phospho-and silicom olybdic heteropoly acids and also phospho-and germanomolybdic heteropo ly acids were found. The chromatographic system using silica gel modif ied with nitrile groups as the stationary phase is of higher selectivt ity than that using unmodified silica gel.