Recent Advances to Ensure Simple, Leak Free GC Column Connections

Oral Presentation

Prepared by K. Lynam, L. Miller
Agilent Technologies, Inc., 2850 Centerville Road, Wilmingtion , DE, 19808, United States


Contact Information: Kenneth_Lynam@agilent.com; 302-636-8162


ABSTRACT

While one of the most basic steps in chromatography, proper column installation can make or break GC and GC/MS system performance and productivity. Forming and maintaining leak free column connections are critical to achieve low background noise, sharp peaks on active compounds, and optimal column resolution and lifetime. Less frequent detector maintenance is another benefit of leak free column connections.
A variety of products are available to install fused silica GC columns. Recent advances in capillary column ferrule and column nut design improve the likelihood of sustaining leak free seals. To get the most of GC and GC/MS systems, a review of the current options available to install GC columns is warranted.

The selection of capillary ferrule materials offers pro’s and con’s which may be related to the application. While easy to seal because they are soft, graphite ferrules are porous making them unsuitable for use in some detectors, including mass spectrometers. Graphite/polyimide composite ferrules are compatible with mass spec, but shrink at high temperatures creating leaks if used with standard column nuts. Both these traditional material ferrules can negatively impact chromatographic results. Recent flexible metal ferrules are stainless steel providing unique advantages over other ferrules, including surface deactivation. However, metal ferrules require care with regard to possible over-tightening and fitting damage.

To ensure robust and reliable seals, the proper column ferrule for the application is combined with a column nut that both properly seats and secures the ferrule during operation. A novel column nut design that extends use of composite ferrules by addressing material limitations is reviewed. Recommendation to improve system productivity and flow path inertness will be discussed.