Quantitative electron probe x-ray microanalysis of biological bulk specimens

Area of Science:

• Analytical Chemistry
• Materials Science
• Biophysics

Background:

• Quantitative X-ray microanalysis of thick biological specimens presents challenges compared to thin sections.
• Existing quantitative methods require further development for bulk biological samples.

Purpose of the Study:

• To provide a detailed examination of ZAF-corrections for bulk biological specimens.
• To address challenges in quantitative elemental analysis using X-ray microanalysis.
• To compare different types of standards and intensity measurement methods.

Main Methods:

• Detailed examination of ZAF-correction components and the ratio model.
• Investigation of secondary fluorescence effects from the continuum in metal analysis (Z>20).
• Comparison of organic (gelatin/resin) and crystal standards for homogeneity and quantitation.

Main Results:

• Organic standards demonstrate superior homogeneity and quantitation performance compared to crystal standards.
• Secondary fluorescence by the continuum is a significant factor in metal analysis of biological bulk specimens.
• Relative intensities (P/B-ratios) generally offer advantages over absolute X-ray intensities for quantitative analysis.

Conclusions:

• ZAF-correction methods and standard selection are critical for accurate quantitative X-ray microanalysis of biological bulk specimens.
• Organic standards and P/B-ratios are recommended for improved quantitation in this field.
• Further research may be needed for specific cases where P/B-ratios are not advantageous.