On-line dynamic two-dimensional admicelles solvent extraction coupled to electrothermal atomic absorption spectrometry for determination of chromium(VI) in drinking water

An on-line dynamic two-dimensional admicelles solvent extraction system was coupled to electrothermal atomic absorption spectrometry (ETAAS) for determination of Cr(VI) in drinking water. As a two-dimensional solvent, admicelles were on-line-prepared by passing cetyltrimethylammonium bromide (CTAB) through a microcolumn packed with silica gel. The analyte Cr(VI) was on-line-complexed with pyrrolidine dithiocarbamate (PDC), and the resulting Cr(VI)-PDC was effectively adsolubilized in the admicelles of the microcolumn, and then quantitatively eluted with 30 mu 1 of acetonitrile for ETAAS determination. All the procedures including the formation and decomposition of admicelles and ETAAS determination were performed on-line, ensuring automatic determination of Cr(VI) in drinking water with a high precision. With a consumption of 2.1 ml sample solution, a detection limit (3 sigma) of 3.0 ng 1(-1), and an enhancement factor of 32 were obtained at a sample throughput of 31 samples h(-1). The precision (R.S.D.) for 11 replicate measurements of 50 ng 1(-1) Cr(VI) was 2.5%. The developed methodology was demonstrated to be reliable and sensitive for automatic determination of ultratrace Cr(VI) in bottled drinking water samples. (c) 2004 Elsevier B.V. All rights reserved.