INVESTIGATIONS OF THE BEHAVIOR OF TELLURIUM(IV) AND SELENIUM(IV) IN ION-EXCHANGE CHROMATOGRAPHY

For the development of an on-column chromatographic method for the sim ultaneous separation and detection of selenium(IV) and tellurium(IV), their chromatographic behaviours on cation and anion exchangers as wel l as on multiphase cation-and anion-exchange/reversed-phase columns, h ave been investigated. The eluent medium consisted of diluted hydrochl oric acid at different concentrations and flow-rates. The detection of selenium(IV) and tellurium(IV) was based on post-column derivatizatio n, of the eluted species, with 1,1,3,3-tetramethylthiourea (TMTU). The TMTU concentration, pH and how-rate was optimized in order to obtain the best sensitivity for both the analytes. The capacity factor value, k', as well as the charge of the species eluted on the different colu mns tested, have been obtained for all experimental conditions. It has been demonstrated that the on-column chromatographic separation betwe en selenium(IV) and tellurium(IV) is achievable by exploiting their di fferent elution patterns on ion exchangers. On the basis of peak symme try and analyte resolution at different concentration ratios, the cati on-exchange mode was chosen. Injecting 50 mu l of samples, detection l imits of 78 and 83 mu g/l for tellurium and selenium, respectively wer e obtained. Concentrations lower than 10 mu g/l could be determined by increasing the injection volume or by means of on-line preconcentrati on. (C) 1997 Elsevier Science B.V.