How to Check for Leaks in a GC System

Maintaining a leak-free GC or GC/MS system is essential for obtaining reliable, reproducible, and accurate results. Even minor leaks can affect chromatography by reducing sensitivity, contaminating samples, and damaging columns or equipment. The positive aspect is that small leaks can be easily identified and prevented from escalating into major issues by using an electronic leak detector to pinpoint their location.

Symptoms of a Leak in the GC

Gas leaks in a GC system can manifest through a range of symptoms. A significant leak often prevents the system from reaching a ready state and triggers an electronic pressure control safety shutdown. This could be caused by issues such as incorrect column installation, a column connected to the wrong inlet or detector, a damaged column, loose or broken fittings or ferrules, cored septa, or tubing blockages. Smaller leaks, on the other hand, typically allow the system to keep running, but may result in symptoms such as fluctuating pressure readings, poor reproducibility or retention times, or elevated 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While you’re probably aware that ‘snoop’ is an outdated method of checking for leaks, you may not be aware of the differences between various electronic leak detectors.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.