SYNCHROTRON X-RAY MICROPROBE DETERMINATION OF CHROMATE CONTENT USING X-RAY-ABSORPTION NEAR-EDGE STRUCTURE

X-ray absorption near-edge structure (XANES) has been applied to the quantitative analysis of chromate (CrO42-) content in oxides, silicate glasses, and simulated cementitous waste forms. The method uses the normalized area of a pre-edge peak (bound-state transition) in XANES spectra acquired with the synchrotron X-ray microprobe on beam line X26A at the National Synchrotron Light Source. The estimated accuracy of the technique is +/- 5% in terms of Cr6+/total Cr. The minimum detection limit approaches 10 ppm Cr6+ using a 150-mum synchrotron X-ray beam. These results demonstrate the value of synchrotron-based microXANES for the nondestructive quantification of the first-row transition metal species present as tetrahedral oxyanions.