Quantitation in x ray microanalysis of biological bulk specimens

Electron probe microanalysis of biological bulk specimens, as compared to thin specimens, is limited by poor X-ray spatial resolution. On the other hand preparation methods for bulk specimens are often much simpler than for thin specimens. With respect to quantitation, however, numerous problems arise, such as poorly known composition of the matrix, local density differences, charging, mass loss, contamination, poorly defined surface topography, etc. The various quantitation methods, commonly used, include the use of ideal and non-ideal standards, the use of P/B-ratios, the calculation of ZAF-correction, and the use of so-called no-standard methods. The accuracy or reliability of the various methods has hardly been systematically investigated. It is shown that approximations from model systems will be necessary. Finally it is expected that the method used for particle analysis will be useful for the investigation of biological bulk specimens.