Online column preconcentration for speciation and selective determination of Cr(III) in natural water samples using flow injection with chemiluminescence detection.

A simple, rapid, sensitive and inexpensive approach is described in this work based on a combination of solid-phase extraction of 8-hydroxyquinoline (8HQ), for speciation and preconcentration of Cr(III) and Cr(VI) in river water, and the direct determination of these species using a flow injection system with chemiluminescence detection (FI-CL) and a 4-diethylamino phenyl hydrazine (DEAPH)-hydrogen peroxide system. At different pH, the two forms of chromium [Cr(III) and Cr(VI)] have different exchange capacities for 8HQ, therefore two columns were constructed; the pH of column 1 was adjusted to pH 3 for retaining Cr(III) and column 2 was adjusted to pH 1 for retaining of Cr(VI). The sorbed Cr(III) and Cr(VI) species were eluted from columns using 3.