Determination of chromium(VI) and lead(II) in drinking water by electrokinetic flow analysis system and graphite furnace atomic absorption spectrometry

An electrokinetic flow analysis system (EKFA) using an electroosmotic pump (Peo) and a bi-directional electrostacking (BDES) unit is introduced in thi s paper. Large flow range, moderate carrier pressure, low performance volta ge and stable flow rate, especially in mul min(-1) level, are the main spec ialties of the Peo. Diethanolamine, 0.5 mM, is selected as its carrier to i mprove the pump efficiency and stability further. Moreover, BIDES, a feasib ility investigation for the simultaneous separation and pre-concentration o f cations and anions, and graphite furnace atomic absorption spectrometry ( GFAAS) determination are presented. The calibration series for both of Cr(V I) and Pb(II) are from 0.2 to 40 mug l(-1) with 10 mul pipette volume and G FAAS determination directly. The detection limit of Cr(VI) and Pb(II) with 10 min BDES is 10 and 13 ng l(-1)(3 sigma of blank, n = 11), respectively. The recovery of Cr(VI) and Pb(II) is (103-105) +/- 1% and (95.9-96.9) +/- 1 .0% with three independent determinations, respectively. The investigated m ethod is also suitable for the simultaneous separation and pre-concentratio n of trace cations and anions in low conductivity sample solutions with dif ferent detection instruments. (C) 2001 Elsevier Science B.V. All rights res erved.