In situ trapping of As, Sb and Se hydrides on nanometer-sized ceria-coated iron oxide-silica and slurry suspension introduction to ICP-OES.

A procedure is developed for the analysis of sub-μg L(-1) levels of arsenic, antimony and selenium after preconcentration of their hydrides. The study highlights the capability of an aqueous suspension of a nanometer-sized magnetic ceria, in the presence of iodide, to function as a sorbent for the in situ trapping and preconcentration of the hydrides of certain metalloids. After extraction, the material is magnetically separated from the trapping solution and analyzed. A slurry suspension sampling approach with inductively coupled plasma-optical emission spectrometry (ICP-OES) is employed for measurements, as the quantitative elution of the adsorbed metalloids is not feasible. The whole analytical procedure consists of five steps: (i) pre-reduction of As, Sb and Se, (ii) generation of the hydrides AsH3, SbH3 and SeH2, (iii) in situ collection in the trapping suspension of magnetic ceria, (iv) isolation of the particles by applying a magnetic field, and (v) measurement of As, Sb and Se concentrations using ICP-OES. Under the established experimental conditions, the efficiency of trapping accounted for 94 ± 2%, 89 ± 2% and 98 ± 3% for As, Sb and Se, respectively, signifying the effective implementation of the overall procedure. The applicability of the procedure has been demonstrated by analyzing tap and lake water and a reference material (soft drinking water). The obtained analytical figures of merit were satisfactory for the analysis of the above metalloids in natural waters by ICP-OES.