How to Check for Leaks in a GC System

To achieve reliable, reproducible, and accurate results, maintaining a leak-free GC or GC/MS system is critical. Even small leaks in the system can negatively impact the chromatography through loss of sensitivity, contaminated samples, and damaged columns or instruments. The good news is that you can easily prevent small leaks from causing big problems by using an electronic leak detector to determine where leaks are occurring.

Symptoms of a Leak in the GC

Gas leaks in a GC system can present themselves in various symptoms. A large leak will typically prevent the GC system from reaching a ready state, and lead to an electronic pressure control safety shutdown. This could be from a column being incorrectly installed/installed in an unexpected inlet or detector, a broken column, broken or loose fittings or ferrules, cored septa, or tubing blockages for example. Smaller leaks will generally allow the system to continue operating, but symptoms can include cycling of actual pressure readings, poor reproducibility or retention time, or higher than normal background noise or bleed.

Where to Check for GC Gas Leaks

Whether or not you’re experiencing symptoms of a gas leak in your GC system, it is good practice to inspect and check your gas lines and instrument regularly. When doing so, it’s recommended to increase the system pressure of the GC while it is cool to accentuate any potential leaks so that they’re easier to detect. Here are ten places to check for leaks throughout the system:

1. Gas supply: while any gas supply can leak, pay extra close attention to the gas regulator if you use cylinders, especially after changing the cylinder out
2. Gas filter connections: check every time a gas filter is changed
3. Shutoff valves: especially prone to leaks as they age
4. EPC connection: critical spot to check for leaks since all gases enter the GC through the EPC connection
5. Split vent trap: easy to overlook
6. Septum or septum nut: a common source of leaks
7. Weldment and weldment lines: weldment can be incorrectly tightened or cracked
8. Reducing nuts: nuts can be loosened from temperature changes
9. Inlet and detector column nuts: loosened nuts or damaged ferrules can cause a leak
10. Column connectors: check them regularly

Benefits of the Restek Electronic Leak Detector

While you’re probably aware that ‘snoop’ is an outdated method of checking for leaks, you may not be aware of the differences between various electronic leak detectors. One of the biggest benefits of the Restek Electronic leak detector is that you can use it while it’s charging if needed (not recommended to do this regularly, but if you haven’t had a chance to charge it fully, it can be done!). If you’d like to discuss this electronic leak detector, or any other chromatography consumables, reach out to our product specialists by our live chat or phone during business hours, or email at any time and we’ll respond as soon as possible.