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 this paper. Large flow range, moderate carrier pressure, low performance voltage and stable flow rate, especially in μl min−1 level, are the main specialties of the Peo. Diethanolamine, 0.5 mM, is selected as its carrier to improve the pump efficiency and stability further. Moreover, BDES, a feasibility investigation for the simultaneous separation and pre-concentration of cations and anions, and graphite furnace atomic absorption spectrometry (GFAAS) determination are presented. The calibration series for both of Cr(VI) and Pb(II) are from 0.2 to 40 μg l−1 with 10 μl pipette volume and GFAAS determination directly. The detection limit of Cr(VI) and Pb(II) with 10 min BDES is 10 and 13 ng l−1(3σ 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 method is also suitable for the simultaneous separation and pre-concentration of trace cations and anions in low conductivity sample solutions with different detection instruments.