On-site Determination of Arsenic, Selenium, and Chromium(VI) in Drinking Water Using a Solid-phase Extraction Disk/Handheld X-ray Fluorescence Spectrometer.

A rapid, simple technique combining disk solid-phase extraction and handheld X-ray fluorescence (XRF) spectrometry was developed for the on-site determination of As, Se, and Cr(VI) in drinking water. For the preconcentration of As, Se, and Cr(VI), a 50-mL aqueous sample was adjusted to pH 4, followed by passage through a Ti-loaded anion-exchange disk (Ti-AED). Both sides of the Ti-AED were coated with an adhesive cellophane tape prior to drying using a cordless hair iron, followed by a handheld XRF measurement. The Ti-AED adsorbed As(III), As(V), Se(IV), Se(VI), and Cr(VI) in water without requiring oxidation and reduction. The detection limits of As, Se, and Cr(VI) were all 1.0 μg L. Good recoveries were obtained by measuring certified reference materials, and spiking natural mineral water with As, Se, and Cr(VI). As the proposed method does not require a power supply or toxic reagents in any analytical step, it is suitable for the on-site determination of toxic elements in drinking water.