ACCURATE SILICATE ANALYSIS BASED ON SEPARATION BY ION-EXCHANGE CHROMATOGRAPHY

A method is presented for the accurate determination of the major and some minor elements in silicate minerals. After sample dissolution and removal of silica, the elements are absorbed from an oxalic-hydrochloric-sulphuric acid mixture on a column of AGI-X8 anion-exchange resin in the oxalate-chloride-sulphate form and a column of AG50W-X8 cation-exchange resin in the hydrogen form. The columns are connected in series. Fe(III), Al(III), Ti(IV), Zr(IV), V(IV) and Mo(VI) are retained by the anion-exchange column, while Mg(II), Ca(II), K(I), Na(I) and Mn(II) pass through and are retained by the cation-exchange column. Phosphate passes through both columns. The columns are disconnected and both groups of elements completely separated by using only the volatile inorganic acids, hydrochloric and nitric acid, and the solvents ethanol and acetone as eluents. Selected titrimetric, spectrophotometric and atomic absorption methods are used for determinations. Very accurate results of analysis of synthetic mixtures and standard rocks are presented together with anion-exchange distribution coefficients in hydrochloric-oxalic acid mixtures and relevant elution curves. © 1969.