Agilent Ultimate Plus Fused Silica Tubing

Significance of the Topic

High inertness and mechanical stability of fused silica tubing are critical for reliable gas chromatographic and GC/MS analyses of reactive or semivolatile compounds at trace levels. Robust tubing minimizes analyte degradation, reduces peak tailing, and extends service life in applications requiring guard columns, transfer lines, or long retention gaps.

Objectives and Study Overview

This study evaluates Agilent Ultimate Plus deactivated fused silica tubing against a comparable product from another supplier. Three performance aspects were assessed: chromatographic inertness using polar and nonpolar test mixtures, thermal stability of the polyimide coating under prolonged high temperature, and mechanical strength via flexibility tests before and after thermal aging.

Methodology and Used Instrumentation

Chromatographic inertness tests employed a tandem-column GC system with an Agilent J&W VF-5ms reference column (30 m × 0.25 mm, 0.25 μm) coupled to either Agilent or competitor tubing of various internal diameters. Two test mixtures were used: Test Mix 60 (cyclohexane solvent with octanol, dimethylphenol, decanol and others at 1 ng on column) and Very Inert Mix 2 (dichloromethane solvent with acids, nitrobutane, trimethyl phosphate and diol). GC conditions included hydrogen carrier at 1.35 mL/min, inlet at 250 °C, split ratios of 1:75 or 1:100, and FID detection at 325 °C. Thermal stability was assessed by exposing tubing to 360 °C for 72 or 144 hours and inspecting polyimide coating discoloration. Mechanical strength was quantified by measuring the minimum bend diameter for 15 cm segments, converting to a force value based on internal diameter.

Main Results and Discussion

Inertness testing with Test Mix 60 showed similar performance for nonpolar n-decane on both tubing types. For polar 1-decanol, Agilent tubing delivered asymmetry factors closer to the ideal value of 1 and higher relative recoveries versus competitor tubing, especially at 0.53 mm id. Very Inert Mix 2 results demonstrated clear separation of trimethyl phosphate, diol, and propylbenzene peaks on Agilent tubing, while competitor tubing exhibited heavy adsorption and peak tailing. Mechanical strength tests indicated comparable forces for 0.12 and 0.18 mm id tubing, with Agilent tubing outperforming the competitor at 0.53 mm id. Thermal aging for 72 hours at 360 °C left the Agilent polyimide coating unchanged, whereas the competitor coating darkened and risked brittleness. Lifetime testing over 144 hours confirmed that Agilent tubing strength remained stable across all diameters except a slight change at 0.53 mm id.

Benefits and Practical Applications

• Superior inertness for reactive polar analytes reduces peak tailing and improves quantitation accuracy.
• Enhanced thermal stability maintains tube integrity and sealing performance during extended high-temperature operations.
• Improved mechanical strength extends tubing lifetime and simplifies handling when installing guard columns, retention gaps, or transfer lines.

Future Trends and Potential Applications

Development of next-generation deactivation chemistries may further reduce interactions with highly active analytes. Integration of fused silica tubing into automated sample-prep and microfluidic systems could enhance high-throughput workflows. Exploration of novel coating materials and miniaturized low-dead-volume fittings will support advanced GC and GC/MS applications in environmental, pharmaceutical, and petrochemical analysis.

Conclusion

Agilent Ultimate Plus deactivated fused silica tubing demonstrates marked improvements in chromatographic inertness, thermal durability, and mechanical robustness compared to a competitive product. These advantages translate into more reliable trace-level analyses, reduced maintenance, and extended tubing life in demanding GC and GC/MS applications.

References

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4. Yamin Wang Analysis of Sulfur Compounds in Petroleum Gases and Natural Gas Application note 5991-4643EN 2014
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6. Anon Agilent J&W Ultra Inert GC Columns Technical Overview 5989-8665EN 2008