Preparation of Specimens for Bulk Analysis Using LECO Glow Discharge Spectrometers (GDS900, GDS850, GDS500)

Importance of the Topic

Glow discharge atomic emission spectrometry (GD-AES) is a powerful technique for direct bulk analysis of solid materials. Its ability to handle diverse sample forms—from large metal blocks to thin wires and powders—makes it invaluable in quality control, materials development, and failure analysis. Reliable sample preparation is essential to achieve accurate, reproducible results and to maintain instrument performance.

Objectives and Overview

This application note aims to present comprehensive procedures and best practices for preparing specimens of different morphologies for analysis on LECO glow discharge spectrometers (GDS900, GDS850, GDS500). The guide covers safety considerations, sample fixturing, size constraints, mounting media, and specialized techniques for challenging sample types.

Methodology and Used Instrumentation

Instrument models: GDS900, GDS850A, GDS500A glow discharge atomic emission spectrometers.
Key methodological steps:

• Ensure flat, clean sample surfaces for proper vacuum sealing and electrical contact.
• Section oversized samples to fit chamber dimensions and maximize analytical face.
• Abrade surfaces with belt grinders or polishers to remove coatings, oxidation, or porosity.
• Mount small or irregular specimens in conductive resin (copper-filled diallyl phthalate) to complete the circuit and dissipate heat.
• Press marginally sized or malleable parts in a hydraulic press to enlarge analytical area.
• Use reusable holders for rods and wires to position them flush with the lamp face.
• Forge ultrafine wires or springs into compact masses for analysis.
• Press powders into pellets after de-lubrication and heat treatment to remove binders.
• Glue thin sheets onto a conductive substrate using two-part epoxy for rigidity and heat sinking.

Main Results and Discussion

Proper specimen preparation directly influences vacuum integrity, plasma stability, and signal quality. Following the dimensional guidelines for each spectrometer model prevents leakage and allows consistent sputtering. Conductive mounts and holders maintain electrical continuity and protect fragile samples from overheating. Heat treatment of green powder metal ensures removal of organic binders, reducing matrix interference. Sectioned and polished faces yield uniform erosion and high-precision depth profiles when combined with proprietary software.

Benefits and Practical Applications

• Rapid, non-destructive analysis of large, irregular, or delicate samples with minimal material waste.
• Versatility across metals, alloys, powders, and coated specimens.
• Accurate bulk composition data for incoming inspection, failure investigation, and process monitoring.
• Capability to generate compositional depth profiles for layered coatings and surface treatments.
• Streamlined workflows using standard laboratory equipment and consumables.

Future Trends and Potential Applications

Advances in glow discharge hardware and software will enhance sensitivity for trace elements and improve resolution of nanometer-scale coatings. Integration with robotics and sample-handling automation promises higher throughput and reduced operator variability. The development of new conductive mounting media and holder designs will extend applicability to sub-millimeter wires, fibers, and composite materials. Expansion into semiconductor, battery, and additive manufacturing sectors is anticipated as instrumental capabilities evolve.

Conclusion

Successful bulk analysis by glow discharge spectrometry relies on meticulous sample preparation tailored to morphology and instrument constraints. LECO’s comprehensive procedures ensure robust vacuum seals, stable plasmas, and reliable quantitative data across a wide range of sample types. Adoption of these techniques optimizes analytical performance and broadens the scope of GD-AES in industrial and research settings.

Reference

LECO Corporation, Application Note: Preparation of Specimens for Bulk Analysis Using LECO Glow Discharge Spectrometers, Form No. 203-821-574, Rev 0, August 2019.