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 h ydride 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 fo r 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 hydrochlo ric acid and sodium tetrahydroborate to generate the hydride. A limit of de tection 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 an d copper metal reference materials (MBH) demonstrated that results were in good statistical accordance with certified values. (C) 2001 Elsevier Scienc e B.V. All rights reserved.