M00001727
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ISO 22309 2nd Edition, October 15, 2011 Microbeam analysis — Quantitative analysis using energy-dispersive spectrometry (EDS) for elements with an atomic number of 11 (Na) or above
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Availability date: 07/13/2021
Description / Abstract:
This International Standard gives guidance on the quantitative
analysis at specific points or areas of a specimen using
energy-dispersive spectrometry (EDS) fitted to a scanning electron
microscope (SEM) or an electron probe microanalyser (EPMA); any
expression of amount, i.e. in terms of percent (mass fraction), as
large/small or major/minor amounts is deemed to be quantitative.
The correct identification of all elements present in the specimen
is a necessary part of quantitative analysis and is therefore
considered in this International Standard. This International
Standard provides guidance on the various approaches and is
applicable to routine quantitative analysis of mass fractions down
to 1 %, utilizing either reference materials or "standardless"
procedures. It can be used with confidence for elements with atomic
number Z 10.
Guidance on the analysis of light elements with Z 11 is
also given.
NOTE With care, mass fractions as low as 0,1 % are measurable
when there is no peak overlap and the relevant characteristic line
is strongly excited. This International Standard applies
principally to quantitative analyses on a flat polished specimen
surface. The basic procedures are also applicable to the analysis
of specimens that do not have a polished surface but additional
uncertainty components will be introduced.
There is no accepted method for accurate quantitative EDS
analysis of light elements. However, several EDS methods do exist.
These are the following:
a) Measuring peak areas and comparing intensities in the same
way as for heavier elements. For the reasons explained in Annex D,
the uncertainty and inaccuracy associated with the results for
light elements will be greater than for the heavier elements.
b) Where the light element is known to be combined
stoichiometrically with heavier elements (Z 10) in the
specimen, its concentration can be determined by summing the
appropriate proportions of concentrations of the other elements.
This is often used for the analysis of oxygen in silicate mineral
specimens.
c) Calculation of concentration by difference where the light
element percentage is 100 % minus the percentage sum of the
analysed elements. This method is only possible with good
beam-current stability and a separate measurement of at least one
reference specimen and it requires very accurate analysis of the
other elements in the specimen.
Annex D summarizes the problems of light element analysis,
additional to those that exist for quantitative analysis of the
heavier elements. If both EDS and wavelength spectrometry (WDS) are
available, then WDS can be used to overcome the problems of peak
overlap that occur with EDS at low energies. However, many of the
other issues are common to both techniques.