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7.1.3 X-Ray Fluorescence

Use: X-ray fluorescence (XRF) spectrometry is a non-destructive, analytical method used primarily to detect heavy metals in soil/solids samples.


XRF spectrometry uses primarily x-rays to irradiate a sample, which causes elements in the sample to emit secondary radiation of a characteristic wavelength. Two basic types of detectors are used to detect and analyze the secondary radiation:

  1. Wavelength-dispersive XRF spectrometry uses a crystal to diffract the x-rays, as the ranges of angular positions are scanned using a proportional or scintillation detector (an extremely sensitive instrument that can be used to detect alpha, beta, gamma, and x-radiation).
  2. Energy-dispersive XRF spectrometry uses a solid-state, Si(Li) detector from which peaks representing pulse-height distributions of the x-ray spectra can be analyzed.

The elements in the sample are identified by the wavelengths of the emitted x-rays while the concentrations of the elements are determined by the intensity of the x-rays. Sample preparation is minimal compared to conventional analytical techniques. XRF spectrometry allows for simultaneous determination of several elements. Portable energy-dispersive XRF instruments are now available, and the more accurate wave length XRF instruments can be used in mobile laboratories. The portable energy-dispersive XRF instruments can be used for scanning the ground surface to determine the prescence of metals without collecting a sample for analysis.


7. Metals


Soil/Sediment Water Gas/Air
BETTER BETTER Requires extraction
Selectivity: Technique measures the contaminant directly.
Susceptibility to Interference: Low.
Detection Limits : 10-100 ppm (soil); 0.5-10 ppm (water). Detection limits range from 20 - 1,000 ppm depending on vendor, unit type, and element analyzed. For portable instruments, detection limits typically are an order of magnitude higher than ICP-AES.
Turnaround Time per Sample: Minutes.
Applicable To:
Screen/Identify Characterize Concentration/Extent Cleanup Performance Long-Term Monitoring
Quantitative Data Capability: Produces quantitative data.
Technology Status: Commercially available and routinely used field techonology.
Certification/Verification: Technology has participated in CalEPA certification and/or CSCT verification program.
Relative Cost per Analysis: Least expensive.


ASTM Standards/EPA Methods:

No applicable ASTM standards or EPA methods are cited for this technology.

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