A review on the extension of Hall's method of quantification to bulk specimen X-ray microanalysis

The theoretical background and the experimental data described in this paper justify the application of the Hall's continuum method of quantitation and the use of bulk crystals of known composition as standards, without ZAF correction, for the biological bulk specimen X-ray microanalysis, provided that proper criteria are respected during the realization of such measurements. The most important points are as follows: (i) Only crystals can be selected where the electrostatic charging is negligible or absent. This depends in part on the own characteristics of the crystals, and can also be facilitated by using low accelerating voltage, e.g. 10 kV, well-conducting specimen holders, and fast scanning rates; (ii) Apart from the element of interest (Na, K, Cl, etc.) all other accompanying components must be of low atomic number (11 or lower), in order to assure the similarity to the composition of the biological matrix where C, O, N and H are the most abundant elements. Comparison of the results in brain and liver cell nuclei and cytoplasm revealed that the elemental concentrations of Na and K are identical within the statistical scatter, if the continuum radiation used for the calculation of the peak-to-background ratios is selected under the respective elemental peak, or farther, in a peak-free region of the spectrum.