Related Experiment Video
Updated: Aug 15, 2026
11:42
Measurement of Total Calcium in Neurons by Electron Probe X-ray Microanalysis
Published on: November 20, 2013
Improvement in Quantitative X-ray Microanalysis of Biological Cryosections
1Department of Physiology, University of Halle, Magdeburger Strasse 6, D-06097 Halle/Saale, Germany
Summary
A new Super Atmospheric Thin Window (SuperATW) on a germanium electron microscope (GEM) detector improves sodium (Na) and calcium (Ca) measurements in biological cryosections. This method also addresses silicon (Si) contamination, crucial for accurate elemental analysis.
Area of Science:
- Analytical Chemistry
- Materials Science
- Biophysics
Background:
- Accurate elemental analysis in biological cryosections is vital for understanding cellular processes.
- Traditional silicon-lithium (Si(Li)) detectors with beryllium (Be) windows have limitations in sensitivity and accuracy for light elements like sodium (Na) and calcium (Ca).
- Silicon (Si) contamination in biological samples can significantly affect elemental concentration measurements.
Purpose of the Study:
- To evaluate the improved accuracy of Na and Ca measurements using a germanium electron microscope (GEM) detector with a Super Atmospheric Thin Window (SuperATW) compared to a Si(Li) detector.
- To assess the impact of Si contamination on elemental analysis in biological cryosections.
- To propose a method for correcting Si contamination in elemental spectra.
Main Methods:
- Comparison of elemental analysis results from Si(Li) and GEM detectors with SuperATW windows using identical biological cryosections.
- Analysis of Na and Ca concentrations in cardiac muscle tissue.
- X-ray mapping to evaluate elemental distribution and sensitivity.
- Development and application of a procedure to measure and subtract Si contamination from elemental spectra.
Main Results:
- The GEM detector with a SuperATW window significantly improved the accuracy of Na measurements in biological cryosections.
- Greater accuracy was achieved for Ca measurements in cardiac muscle using the GEM detector.
- Si contamination was found to be unpredictable and variable within cells, necessitating correction.
- The improved sensitivity of the SuperATW/GEM system is particularly advantageous for X-ray mapping over spot mode analysis.
Conclusions:
- The SuperATW window on a GEM detector offers enhanced accuracy for Na and Ca quantification in biological cryosections.
- A standardized procedure for measuring and subtracting Si contamination is essential for reliable elemental concentration calculations.
- This improved analytical approach is critical for detailed cellular and tissue analysis.
Related Concept Videos
01:10X-ray Diffraction of Biological Samples
X-ray diffraction or XRD is an analytical tool that utilizes X-rays to study ordered structures such as crystalline organic and inorganic samples, polycrystalline materials, proteins, carbohydrates, and drugs.
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
01:28Cryo-electron Microscopy
Conventional electron microscopy (EM) involves dehydration, fixation, and staining of biological samples, which distorts the native state of biological molecules and results in several artifacts. Also, the high-energy electron beam damages the sample and makes it difficult to obtain high-resolution images. These issues can be addressed using cryo-EM, which uses frozen samples and gentler electron beams. The technique was developed by Jacques Dubochet, Joachim Frank, and Richard Henderson, for...