Installing a Uniliner® Liner without an Adaptor in a Standard Packed Column Injection Port

Importance of the topic

The direct installation of a Uniliner® liner without an adaptor in packed column injection ports is critical to ensure reproducible gas chromatographic performance. Proper sealing at the injector significantly affects sensitivity, peak shape, and column lifetime by preventing leaks and column damage.

Objectives and Overview

This guide outlines a step-by-step procedure for installing Uniliner liners in both direct injection and on-column modes when an adaptor is not available. It covers column preparation, liner seating, ferrule installation, leak checking, and head pressure optimization.

Methodology and Instrumentation

Key steps include:

• Injector port preparation by removing internal components for on-column operation.
• Selecting the appropriate Uniliner liner (direct or on-column mode).
• Precision cutting of the fused silica column ends using a ceramic wafer to obtain square cuts and prevent internal damage.
• Assembly of the stainless steel reducer, graphite ferrule, and tightening protocol to avoid crushing the column tip.
• Adjustment of liner depth (approximately 1/32″ below the septum) to ensure optimal seating without distorting solvent peaks.
• Gas flow setup and head pressure calibration to achieve 5–10 mL/min carrier gas flow, guided by recommended pressures for typical column lengths and 0.53 mm ID.
• Leak verification using a helium leak detector; avoiding liquid leak detection methods that may contaminate the column.

Main Points and Discussion

Ensuring a perfectly square column end is essential to forming a reliable seal against the liner taper. Over-insertion of the ferrule can crush the column, leading to distorted solvent peaks. Proper torque on the reducer nut and ferrule delivers a stable, leak-free connection. The illustrative head pressure table provides baseline pressures (2–14 psig) for 15–105 m column lengths at 0.53 mm ID to maintain consistent flow rates.

Benefits and Practical Applications

Following this protocol enables laboratories to:

• Install liners without specialized adaptors, improving flexibility in instrument maintenance.
• Achieve reproducible, high-quality chromatographic data with optimal peak shapes.
• Extend column lifespan by minimizing mechanical stress and leaks.

Future Trends and Potential Applications

The development of integrated liner-column assemblies and low-dead-volume fittings may further simplify installation. Automated port adapters and advanced ferrule materials could reduce manual adjustments, enhancing throughput in high-volume laboratories. Adaptation to sub-2 µm particle columns and micro-bore formats represents a next step in GC evolution.

Conclusion

This installation method provides a reliable approach for incorporating Uniliner liners into packed column injection ports without adaptors. Adherence to precision cutting, proper ferrule seating, and careful flow calibration ensures leak-free connections and robust chromatographic performance.