Fused Bead
Definition
A preparation method where soil is dissolved in molten lithium tetraborate or metaborate flux at around 1100 degrees Celsius to form a glass disc, eliminating particle-size and mineralogical matrix effects for precise major-element analysis.
- Flux material
- Lithium tetraborate or metaborate
- Process temperature
- Around 1100 degrees Celsius
- Result
- Homogeneous glass disc
- Benefit
- Removes particle-size and mineralogical matrix effects
Common questions
Why go to the trouble of fusing a soil sample instead of pressing a powder pellet?+
A pressed pellet retains variation in grain size and mineral form that can bias X-ray fluorescence intensities for major elements, while melting the sample into a glass homogenises it completely, so intensity differences reflect only concentration.
What is the tradeoff of using a fused bead for trace-element or forensic comparison work?+
The high dilution needed for a stable bead lowers sensitivity for trace elements, so fused beads suit major-element characterisation while trace-element and provenance comparisons often still rely on pressed pellets or other techniques such as ICP-MS.
Related terms
- Energy-Dispersive XRF (ED-XRF)
- An XRF configuration using a solid-state detector that registers all emitted photon energies simultaneously. Faster and more compact than WD-XRF, enabling portable...
- Matrix Effect
- The absorption or enhancement of characteristic X-rays by other elements in the same sample, causing apparent concentrations to deviate from true values...
- Pressed Pellet
- A sample preparation form in which finely ground, dried soil is mixed with a binder and compressed under several tonnes of pressure...
- Wavelength-Dispersive XRF (WD-XRF)
- An XRF configuration that uses an analysing crystal to separate emitted X-rays by wavelength before detection, giving high spectral resolution and low...
- X-Ray Fluorescence (XRF)
- A technique in which a sample is irradiated with a primary X-ray beam, causing its constituent elements to emit characteristic secondary (fluorescent)...