A method for preparing absolute standards for quantitative calibration and measurement of section thickness with X-ray microanalysis of biological ultrathin specimens in EMMA.

Specimen thickness is determined using X-ray microanalysis in conjunction with atomic absorption spectrophotometry. Specimens of evaporated metal films and standards comprising fixed concentrations of element (such as potassium) in organic media are used to determine elemental concentrations of endogenous elements in embedding resin, from which section thickness can also be determined. The method finally depends only on the single measurement of X-ray emission of such an element in the specimen. Calibration of the X-ray detector over the energy range with mineral salts enables the standard to be used for the quantitative analysis of any element under investigation.