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Trace Element Quantitation in Biological X-Ray Microanalysis

Published online by Cambridge University Press:  02 July 2020

R.D. Leapman ,
C.R. Swyt-Thomas ,
D. v. Agoston ,
N. Pivovarova  and
S.B. Andrews
R.D. Leapman
Affiliation:
Biomedical Engineering & Instrumentation Program, DIRS, ORS; National Institutes of Health, Bethesda, MD, 20892.
C.R. Swyt-Thomas
Affiliation:
Biomedical Engineering & Instrumentation Program, DIRS, ORS; National Institutes of Health, Bethesda, MD, 20892.
D. v. Agoston
Affiliation:
Laboratory of Developmental Neurobiology, NICHD, National Institutes of Health, Bethesda, MD, 20892
N. Pivovarova
Affiliation:
Laboratory of Neurobiology, NINDS, National Institutes of Health, Bethesda, MD, 20892
S.B. Andrews
Affiliation:
Laboratory of Neurobiology, NINDS, National Institutes of Health, Bethesda, MD, 20892
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Extract

In high-resolution biological energy-dispersive x-ray (EDX) microanalysis it is often necessary to measure very low elemental concentrations. As an example, calcium, a physiologically important element, typically occurs in subcellular compartments at concentrations of 10-100 atomic parts per million (corresponding to 1-10 millimole/kg dry weight of sample) and it is ultimately desirable to measure the concentration of this element with a standard error of ±1 atomic ppm (or ± 0.1 millimole/kg). Detection of calcium in biological specimens is further complicated by the presence of relatively high levels of potassium (around 0.5 atomic % or 500 millimole/kg), which gives rise to overlap of the K Kβ and Ca Kα peaks in the EDX spectrum. Counting statistics are frequently the limiting factor for detectability, but this is not necessarily the case because in the analytical electron microscope it is possible to collect spectra for long periods using a high probe current.

Type
30 Years of Energy Dispersive Spectrometry in Microanalysis
Information
Microscopy and Microanalysis , Volume 4 , Issue S2: Proceedings: Microscopy & Microanalysis '98, Microscopy Society of America 56th Annual Meeting, Microbeam Analysis Society 32nd Annual Meeting, Atlanta, Georgia July 12-16, 1998 , July 1998 , pp. 212 - 213
Copyright
Copyright © Microscopy Society of America

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References

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