Injection port liners are the last borosilicate glass components commonly used inside the GC instrument. We still use borosilicate liners because only very simple tubes have been available in fused quartz. Many have said that it is impossible to make GC liners from fused quartz – it’s too hard to work (glassblowing) and costs too much. IQ has proven that this is simply not true and we now offer Agilent compatible liners made from fused quartz for about the same price as borosilicate liners: ZenLiner™.
Where the adoption of fused silica capillary for making columns was driven by improved column lifetime and greatly reduced activity and borosilicate press fit connectors were largely replaced by fused quartz because they seal better on fused silica columns, there are far more reasons to choose fused quartz over borosilicate glass for injection port liners.
The injection port liner is the second largest analyte exposed surface in the GC, after the column itself. Arguably, it is more important to have an inert injection port liner than any connector or sample vial. The surface area of an injection port liner is on the same order as sample vials, and while it is true that samples spend a great deal more time in vials than in liners, quantity of sample in the vial is typically huge in comparison and vials are typically at ambient temperature.
Fused quartz has ~500-fold less heavy metals than borosilicate glass (reactivity).
Fused quartz has ~5000-fold less surface activity than borosilicate glass.
Fused quartz has ~30% higher thermal conductivity than borosilicate glass.
Fused quartz is ~50% harder than borosilicate glass (less scratching).
Fused quartz’ upper use temperature (1200C) is far above any injection port maximum where borosilicate glass’ upper use temperature (230C) falls below many injection port maxima.
Fused quartz liners won’t fracture in hot swapping, ever.
In fact, fused quartz is so inert that most chromatographers don’t even consider deactivating fused quartz press fit connectors. The fact is that most analyses don’t require deactivated fused quartz liners and where bare liners work you’ll never have to be concerned with deactivation degrading: there isn’t any there to fail.
ZenLiner™ is also available with SilcoNert® 2000 deactivation for analyses with degradation sensitive analytes in trace quantities.
While SilcoNert 2000 ZenLiners are a bit more expensive than some borosilicate liners, they last far, far longer because SilcoNert 2000 is thermally stable, it resists degradation by oxygen and moisture and, even as it degrades the surface that is exposed is hundreds to thousands of times more inert than is the case for borosilicate.