Understanding Calibration for Glow Discharge Atomic Emission Spectrometry (GD-AES)

Importance of the Topic

Accurate calibration in Glow Discharge Atomic Emission Spectrometry (GD-AES) underpins reliable elemental analysis in industries ranging from metallurgy to surface coatings. Ensuring traceability to certified reference materials and maintaining linear response over broad concentration ranges are critical for quality control, materials development, and failure analysis.

Aims and Overview of the Study

The document reviews general considerations for GD-AES calibration on the LECO GDS850A instrument. It addresses both bulk quantitative analysis and quantitative depth profiling (QDP), outlining approaches to establish robust working curves, correct for sputter rate variability, and apply calibrations across diverse material matrices.

Methodology and Instrumentation

Sampling relies on a Grimm-style glow discharge lamp with defined anode diameters (2 mm and 4 mm) and argon sputtering under controlled partial pressure. Calibration curves are generated by measuring certified reference materials traceable to NIST or ISO Guide 31 standards at multiple specimen locations.

Used Instrumentation

• LECO GDS850A Glow Discharge AES system
• Grimm-style glow discharge lamp (7 mm or 15 mm o-ring configurations)
• Array detectors and photomultiplier tubes for signal acquisition

Main Results and Discussion

Bulk calibration yields linear working curves spanning ppm to high-percent concentration levels, enabling accurate interpolation and modest extrapolation. Figure 1 (Pb in Cu) demonstrates normalized linear response up to >16 % concentration. QDP calibration uses sputter rate correction to unify working curves across different alloys. Without correction, calibration families cluster by matrix; with correction, a single linear curve is recovered (Figures 4 and 5). Depth profiles (Figure 6) illustrate transition from Zn coating to Fe substrate, quantifiable without external thickness standards.

Benefits and Practical Applications

• Robust quantification for bulk metals and thin films
• Elimination of profilometers for depth profiling
• Applicability to galvanizing, electroplating, PVD/CVD, heat treatments, oxides, and painted layers
• Traceability to recognized standards for regulatory compliance

Future Trends and Potential Applications

Advancements in detector technology and data processing will further improve sensitivity and dynamic range. Integration of automated sputter rate determination and machine-learning calibration algorithms may streamline method development. Expanding certified reference material libraries for novel alloy systems will broaden GD-AES adoption in emerging materials research.

Conclusion

GD-AES calibration on the LECO GDS850A platform demonstrates reliable, traceable elemental quantification for both bulk and depth-resolved analyses. Sputter rate correction is essential for multi-matrix calibrations, enabling unified working curves and accurate profiling of layered structures without auxiliary thickness measurements.

Reference

• ASTM E135 – Terminology for Analytical Chemistry for Metals, Ores, and Related Materials
• ASTM E158 – Fundamental Calculations to Convert Intensities into Concentrations in Optical Emission Spectrochemical Analysis
• ASTM E305 – Establishing and Controlling Spectrochemical Analytical Curves
• ASTM E406 – Using Controlled Atmospheres in Spectrochemical Analysis
• ASTM E415 – Optical Emission Vacuum Spectrometric Analysis of Carbon and Low-Alloy Steel
• ASTM E520 – Describing Photomultiplier Detectors in Emission and Absorption Spectrometry
• ASTM E1009 – Evaluating an Optical Emission Vacuum Spectrometer to Analyze Carbon and Low-Alloy Steel
• ASTM E1507 – Describing and Specifying the Spectrometer of an Optical Emission Direct Reading Instrument