High Definition X-ray fluorescence (HDXRF)

Poster-Vendor
Poster Presentation

Prepared by L. Heffner
XOS, 15 Tech Valley Drive, East Greenbush, NY, 12061, United States


Contact Information: lheffner@xos.com; 518-880-1508


ABSTRACT

Traditional handheld x-ray fluorescence (HHXRF) is an essential tool for rapid screening of heavy metal soil contamination at brownfield sites. From initial site characterization to remediation, the ability to detect high levels of lead, mercury, arsenic and other contaminants at industrial and mining sites has unlocked the ability to assess the spatial distribution of contamination in a cost-effective manner. However, this value is compromised when the limits of detection (LOD) for heavy metals are above regulatory limits, requiring wet chemistry quantification in areas where detected levels are below the instrument sensitivity. Further issues arise when there is interference between contaminants and the host matrix, leading to inaccurate measurements or substantially degraded LODs.

To address the shortcomings of standard XRF techniques, an energy-dispersive X-ray fluorescence (EDXRF) spectrometry technique with multiple monochromatic excitation beams can be used to achieve regulatory-level detection of heavy elements in soil on site, with minimal sample preparation, and no hazardous chemicals. This method, known as High Definition X-ray fluorescence (HDXRF), uses high, medium and low energy monochromatic beams in sequence to provide a broad range of elemental sensitivities and interference effects to be minimized. Recently ASTM D8064-16 established a standard test method for elemental analysis of soil and solid waste for the determination of Pb, Hg, As, Cd, Ni and Cr at levels ranging from 1 to 5000 mg/kg, indicating excellent repeatability of the measurements with NIST standards.

This technology was crucial for a site characterization performed by the NYS Department of Environmental Conservation at the Geneva Foundry site and surrounding town. Over the course of 125 years in operation, the Geneva foundry produced airborne pollution containing lead and arsenic, resulting in an extensive heterogeneous distribution of soil contamination. The history of the site, combined with its proximity to other potential sources of heavy metal contamination, made it necessary to perform extensive sampling over a large area with very low limits of detection for Arsenic. With prep-free, fast sampling times facilitated by HDXRF , and a low number of confirmatory samples requiring wet chemistry, the DEC reduced the time and costs of the site characterization while producing a complete analysis indicating the extent of the contamination attributable to the foundry.