STANDARDS FOR ELECTRON PROBE MICROANALYSIS OF BIOLOGIC SPECIMENS

A procedure is described for the preparation and application of gelatin standards in the quantitative elemental analysis of microscopic portions of tissue sections in the electron microprobe x-ray spectrometer. Ten to fifteen per cent gelatin solutions containing varying concentrations of the elements to be measured are quick-frozen in capsules, sectioned in a cryostat at the same thickness as the tissue and freeze-dried. Standard sections are mounted with each tissue section, carbon-coated and analyzed simultaneously. Concentrations of the elements in portions of the tissue as small as 10–12 liters are then determined directly from a regression curve or equation derived from the standards.