Most micro-XRF instruments use a theoretical quantification method called fundamental parameterisation.
Fundamental parameters are derived from the Sherman equation (Sherman, 1955) and use the atomic parameters of individual elements (e.g. absorption, scattering and emission parameters) to calculate the X-ray intensities that would be expected for any given concentration.
The fundamental parameter model can overcome heterogeneity and matrix variations commonly observed in traditional XRF instrumentation. Using this database, the fundamental parameter algorithms can calculate the concentration of each element in weight percent, which is then normalised to 100%, eliminating the requirement for physical standards.
Image 1: Micro-XRF Bruker M4 TORNADO.
Photo courtesy of Portable Spectral Services.