"Standardless" quantitative electron probe microanalysis with energy-dispersive X-ray spectrometry: is it worth the risk?

"Standardless" procedures for quantitative electron probe X-ray microanalysis attempt to eliminate the need for standardization through calculation of standard (pure element) intensities. Either "first principles" calculations, which account for all aspects of X-ray generation, propagation, and detection, or "fitted standards" calculations, which use mathematical fits to measured intensities from a limited set of pure standards, can form the basis for standardless analysis. The first principles standardless analysis procedure embedded in the National Institutes of Health/National Institute of Standards and Technology comprehensive X-ray calculation engine and database, Desktop Spectrum Analyzer, has been tested against spectra measured on NIST standard reference materials, research materials, and binary compounds. The resulting distribution of errors is broad, ranging from -90% to +150% relative. First principles standardless analysis can thus lead to unacceptably large errors.