Installation Instructions for 5mm Uniliner® Inlet Liner with Adaptor in 1/4-inch Injection Port

Significance of the Topic

Gas chromatography inlets require precise alignment and sealing when converting from packed to capillary columns. Specialized inlet liners and adaptors enable reproducible injections, optimal peak shapes, and leak-free performance.

Objectives and Study Overview

This application note presents a detailed protocol for installing a 5 mm Uniliner inlet liner with a 1/4-inch adaptor. It covers both direct and on-column injection approaches to achieve superior chromatographic results via a secure, leak-tight interface and a controlled expansion chamber.

Methodology and Used Instrumentation

Installation comprises these key steps:

• Select the injection mode (direct or on-column) and slide the Uniliner liner into the adaptor.
• Attach the adaptor to the injector body using a 1/4-inch stainless steel nut; tighten 1/4-turn past finger-tight.
• Trim each column end (~10 cm) with a ceramic wafer to ensure square cuts; mount 0.8 mm graphite ferrules and 1/16-inch nuts.
• Insert the column into the adaptor, maintain a 1 inch gap to the septum, then seat and tighten the ferrule to secure the column.
• Adjust the liner position by 1/32-inch and retighten the ferrule until the column is immobile under moderate force.
• Verify carrier gas flow (5–10 cc/min) and leak integrity using an electronic leak detector; avoid liquid leak sprays.

Primary components include:

• 5 mm Uniliner inlet liner
• 1/4-inch Uniliner inlet liner adaptor
• Septum nut, injector body, and solvent expansion chamber
• Graphite ferrules and stainless steel nuts
• Fused silica capillary columns (0.32 mm or 0.53 mm ID)
• Electronic leak detector (Restek Leak Detector, cat.# 22839)

Main Results and Discussion

When properly installed, the system delivers:

• Leak-free connections robust to mechanical stress.
• Sharpened peak shapes with minimal tailing.
• Recommended head pressures for helium or hydrogen: 3–30 psig for 0.32 mm ID columns and 2–14 psig for 0.53 mm ID columns, varying by column length.

Benefits and Practical Applications

• Seamless switching between direct and on-column injections.
• Enhanced inertness using Siltek-treated liners to reduce analyte adsorption and background signals.
• Improved reproducibility and sensitivity for trace analysis in environmental, food safety, and petrochemical laboratories.

Future Trends and Potential Uses

Expected developments include:

• Next-generation deactivation coatings for ultra-low bleed and higher thermal stability.
• Smart inlet fittings with integrated sensors for real-time diagnostics.
• Miniaturized injection systems for microvolume analyses and high throughput workflows.

Conclusion

Adherence to the outlined installation protocol for Uniliner inlet liners and adaptors ensures consistent, high-quality GC performance. Precise column cutting, correct adaptor assembly, and thorough leak testing are critical for reliable analytical outcomes.

References

1. Restek Online Column Installation Guide, Restek Inc.
2. U.S. Patent 6,444,326 (Siltek Deactivation Process).