Assessment of element-specific homogeneity in reference materials using microanalytical techniques

Area of Science:

• Nuclear analytical techniques
• Materials science
• Analytical chemistry

Background:

• The International Atomic Energy Agency (IAEA) initiated a coordinated research program (CRP) in 1994.
• The CRP focused on "Reference Materials for Microanalytical Nuclear Techniques" to improve analysis quality in member states.
• The program aimed to support the analysis of nuclear, environmental, and biological materials.

Purpose of the Study:

• Identify suitable biological reference materials for quality control in microanalysis.
• Evaluate existing certified reference materials (CRMs) for microanalytical applications.
• Assess sample pretreatment procedures and analytical techniques for homogeneity determination.

Main Methods:

• A 4-year coordinated research program involving seven laboratories and the IAEA's Seibersdorf Laboratories.
• Evaluation of candidate reference materials (IAEA 338 lichen, IAEA 413 algae) for elemental distribution (e.g., Cl, K, Ca, Cr, Mn, Fe, Zn, As, Br, Rb, Cd, Hg, Pb).
• Application of quantitative characterization of homogeneity to potential reference materials.

Main Results:

• Each element shows a characteristic distribution within a matrix, described by "Ingamels' sampling constant" or Kurfuerst's "relative homogeneity factor."
• These concepts are valid across a wide range of sample masses (0.1 µg to 100 mg).
• Characterized materials can be used for experimental determination of total uncertainty in analytical techniques.

Conclusions:

• This study presents the first quantitative characterization of homogeneity for potential reference materials.
• The feasibility and utility of quantitative homogeneity characterization for enhancing quality control in microanalytical techniques are demonstrated.
• The findings support improved quality assurance in nuclear analytical technologies.