Agilent UltiMetal Plus Stainless Steel Deactivation for Tubing, Connectors, and Fittings

Significance of Metal Surface Deactivation in GC Flow Paths

Accurate analysis of polar and reactive compounds at trace levels requires inert flow-path surfaces to prevent adsorption, catalytic breakdown or tailing on metal components.

Objectives and Overview of the Study

This study evaluates Agilent UltiMetal Plus deactivation chemistry applied to stainless steel tubing, connectors and fittings, comparing performance against bare stainless steel and alternative deactivation methods under various chromatographic conditions.

Methodology

• Post-column (tandem) and reversed-tandem test setups using a reference GC column and flame ionization detector.
• Test mixtures: Test Mix 60 (alcohols, amines, acids, alkanes) and Very Inert Mix (acidic, basic, polar probes at nanogram levels).
• Measured parameters: peak asymmetry, absolute and relative recoveries, retention index shifts, and system bleed.
• Components tested: capillary tubing (0.25–0.75 mm id), transfer lines (1/16″ od), bulk tubing (1/16″–1/4″ od), and guard columns (0.25 mm and 0.53 mm id).
• Flexibility tests: bending to small radii (2.5 cm and 10 cm); thermal stability: prolonged exposure at 450 °C.

Instrumentation Used

• Agilent 7890A GC systems with split/splitless inlets and FID.
• Agilent J&W VF-5ms and HP-5ms GC columns (30 m × 0.25–0.32 mm id).
• UltiMetal Plus deactivated stainless steel tubing (CP6581, CP6573), UltiMetal-coated connectors/ferrules (G3182-60580).
• Megabore GC columns and deuterated internal standards for EPA8270 short mix.

Main Results and Discussion

• UltiMetal Plus components delivered low tailing (asymmetry ~1.1–1.3) and high recovery (>90 %) for challenging probes; bare stainless steel adsorbed many analytes irreversibly.
• Performance exceeded that of other deactivation treatments and deactivated fused-silica tubing in inertness tests.
• Uniform deactivation along 30 m capillary tubing yielded consistent performance across all 5 m segments (RSD <3 %).
• External UltiMetal coating remained intact and visually unchanged after five days at 450 °C, unlike oxidized untreated steel.
• Bending to diameters down to 2.5 cm did not impair inertness, indicating mechanical robustness.

Benefits and Practical Applications

• Improved peak symmetry and reproducibility for trace analysis in environmental, food-safety and pharmaceutical labs.
• Lower detection limits and enhanced linearity at ppb and sub-ppb levels.
• Reduced maintenance and sample carryover, extended component lifetimes.
• Compliance with methods requiring stainless steel flow-path hardware, avoiding revalidation.

Future Trends and Potential Applications

• Extension of inert-surface technologies to valves, autosampler components and GC×GC manifolds.
• Integration with high-throughput GC/MS for ultra-trace screening.
• Predictive modelling of surface-analyte interactions using machine learning to tailor deactivation layers.
• Adoption in portable and miniaturized GC systems for field analysis of polar pollutants.

Conclusion

Agilent UltiMetal Plus offers superior deactivation of stainless steel flow-path surfaces, delivering reproducible, low-tailing chromatography of reactive analytes at trace levels with proven thermal and mechanical robustness.

References

• UltiMetal Plus – Advanced Chemistry for Stainless Steel Surface Deactivation. Agilent Technologies, Tech. Overview, 5991-3357EN (2014).
• K. Lynam. Agilent Inert Flow Path Enhancements Improve Drugs of Abuse Testing. Agilent Appl. Note, 5991-1859EN (2013).
• Agilent Ultimate Union Kits (G3182-60580 & G3182-60581). Installation Guide, Agilent Technologies (2013).
• J. Luong, R. Gras, W. Jennings. Journal of Separation Science 30, 2480 (2007).
• Agilent J&W Ultra Inert GC Columns: A New Tool to Battle Challenging Active Analytes. Agilent Tech. Overview, 5989-8665EN (2008).