On-line copper and iron removal and selenium(VI) pre-reduction for the determination of total selenium by flow-injection hydride generation-inductively coupled plasma optical emission spectrometry

Selenium was determined ill samples with high copper and iron contents by hydride generation-inductively coupled plasma optical emission spectrometry (HG-ICP-OES) after flow-injection (FI) on-line copper and iron removal and selenium(VI) reduction. A Dowex 1X-8 anion-exchange microcolumn was used for the separation of selenium from copper and iron as their chloro-complexes. Se(VI) was then reduced on-line by heating a PTFE coiled reactor (150 cm long, 0.7 mm i.d.) in a 100 degreesC water bath. After reduction of Se(VI), a 900-mul sample was injected into the carrier stream containing hydrochloric acid and sodium tetrahydroborate to generate the hydride. A limit of detection of 0.4 mug l(-1) (RSD 2.3% for 20 mug l(-1) selenium) was obtained. The application of the method to Geochemical Standard Reference Samples and copper metal reference materials (MBH) demonstrated that results were in good statistical accordance with certified values. (C) 2001 Elsevier Science B.V. All rights reserved.