Electron probe microanlysis (EPMA) is a non-destructive technique used for high-sensitivity, quantitative determination of the elemental composition of a material.

This technique focuses an energetic beam of electrons onto the sample surface, thereby stimulating x-ray fluorescence. The wavelength of the x-ray is characteristic of the fluorescing element. The strength of that x-ray signal relates then to the abundance of its element within the excited volume, the depth the element is within the sample, and the effects of other elements in the sample. Similarly, to Wavelength Dispersive X-ray Fluorescence Spectroscopy (WDXRF), EPMA systems use wavelength-dispersive spectroscopy (WDS) detectors – which act like diffraction gratings – calibrated to detect various x-ray wavelengths.. By using wavelength-analyzers, EPMA achieves high resolution separation of emission lines, with low background, allowing for quantitative sensitivity to 10 ppm with appropriate use of reference standards. Additionally, because EPMA systems like Scanning Electron Microscopes , can be used to generate 2D element maps by measuring fluorescence at multiple points in a raster-scan.

The EPMA system utilized at Covalent also contains an energy dispersive x-ray spectroscopy (EDS) detector that can quickly obtain entire XRF spectra from points on the sample, albeit with much lower spectral resolution and sensitivity. This allows for rapid identification of the elements present to expedite quantitative analysis of their respective concentrations.