SOLID-PHASE EXTRACTION PROCEDURE FOR THE DETERMINATION OF SELENIUM BY CAPILLARY GAS-CHROMATOGRAPHY

A solid-phase extraction procedure to be used in the determination of selenium by gas chromatography with electron-capture detection (GC-ECD) was investigated. After derivatization of Se(IV) with 1,2-diamino-3,5-dibromobenzene the formed 4,6-dibromopiazselenol was adsorbed on a porous divinylbenzene polymer. Elution was performed with toluene. The proposed solid-phase extraction procedure was compared with a liquid-liquid extraction procedure and the overall efficiency was approximately 97% for sample volumes between 5 and 100 ml. Concordant results were obtained for natural water samples spiked with selenium between the GC-ECD procedure and a hydride generation atomic absorption spectrometric procedure. Removal of dissolved organic carbon in natural waters on XAD-8 and Dowex 1X8 prior to selenium determination was also studied.