Sequential/bead injection lab-on-valve incorporating a renewable microcolumn for co-precipitate preconcentration of cadmium coupled to hydride generation atomic fluorescence spectrometry

A sequential/bead injection lab-on-valve apparatus incorporating a renewable microcolumn packed with co-polymeric immobilized C-18 microbeads was applied to the on-line co-precipitate separation/preconcentration of ultra-trace cadmium by hyphenating with hydride generation atomic fluorescence spectrometry. Cadmium was co-precipitated with lanthanum hydroxide and collected on a microcolumn in the lab-on-valve. The co-precipitate was eluted with hydrochloric acid and directed to meet tetrahydroborate and facilitate hydride generation. The hydride was separated from the reaction mixture and was swept into the atomizer. With a sampling volume of 500 mu l, quantitative retention of cadmium was achieved, along with an enrichment factor of 9.8 and a sampling frequency of 11 h(-1). A detection limit of 3.5 ng l(-1) was derived, along with a RSD of 1.6% (0.1 mu g l(-1)). The procedure was validated analyzing cadmium in certified reference materials.