Separation of microgram quantities of Cr(III) and Cr(VI) in aqueous solutions and determination by energy dispersive X-ray fluorescence spectrometry

A procedure was developed for the separation and independent determination of microgram quantities of Cr(VI) and Cr(III) in aqueous solution. Cr(VI) was adsorbed onto zirconium-loaded activated charcoal (ZrC ∗), and Cr(III) was collected by Fe(OH)3 precipitation and the precipitate bound to activated charcoal. Chromium in the activated charcoal was measured by energy dispersive X-ray fluorescence spectrometry. The detection limits for both chromium species were better than 0.05 mg/l. The procedure was tested with the Ground Water and Waste Water Pollution Control Check Standard WP-15 spiked with Cr(VI) and several samples from the plating industry.