Does Your Laboratory Instrument Have Gas?

Get your (chromatography) gasses in check!

I’ll bet you never considered gas lines as a root cause of chromatography issues in your laboratory! Why would you? They have always been there, so what changed?

The truth is, there are many ways your gas line can affect your chromatography and the health of your gas-phase chromatograph. Age of the lines, placement, existence of filters, and so much more factor Ito these issues.

I have two real-life examples I will detail below:

  • Temperature & Baseline
  • Gas Quality & Filters

Temperature & Baseline

Laboratory temperatures, length of gas lines, and tank storage conditions all affect chromatography and baseline for GCs (even the gas flows and retention times). Every lab should have stable environmental conditions that fall inside of the manufacturer’s specifications.

What if there is a change inside of the lab that isn’t considered and new issues arise with a GC or GCMS? (Some of the details provided here can also help in troubleshooting other system issues, such as LC retention times/baseline shifts.)

I was sent to a customer for “rising baseline issues after several runs”. This isn’t something that is easily troubleshot, as it happens after a long period of running samples. The answer? A lot of questions, looking for any changes to the system or lab and trying to find out if any other systems are affected.

In questioning the customer I could not get any actionable service to the system, BUT I was able to find that it was almost always around the 8-hour mark that the baseline started to rise AND there were no other systems affected. This gave me something to measure. The next step in the process was to look at what was different in this system compared to others on the bench (Luckily there were several other systems on the same bench and on the same gas line supplies.).

Everything was exactly the same on all systems, except when I inspected the back of the GCs. The heat deflector for the oven exhaust had been removed on this particular system. In speaking with the customer, another Engineer had worked with the system the week prior. I concluded the hot air was steadily warming the gas lines over time until they were higher than the system electronics could compensate for (along with leaching materials off the inside of the lines themselves).

The onsite Engineer didn’t believe my root cause analysis, but after returning the heat deflector and running the system for a couple of days, the cause was confirmed and the call was closed.

Gas Quality & Filters

This story is a short one as it involves a contaminated tank of helium in a small lab with 4 PerkinElmer GCs.

The new tank of (contaminated) helium was delivered and hooked to the single point of supply for the lab. All 4 GCs used helium for the carrier flow and FID makeup.

STOP: If this happened in your lab, what is the maximum amount of damage that would be caused? Think carefully. Do you actually have an answer?

In this case, no filters were used on any of the gasses.

What had to be replaced:
All helium lines, all inlets, all PPC modules (inlets & detectors), detector base assemblies, and all columns. This was $5-10k worth of part replacement per instrument, plus labor!

The gas company was unwilling to take any fault but opted to cover 50% of the damages. Other similar, more fortunate cases, involve the wrong gas being in the tanks. You must protect your equipment and know the risks created by the laboratory environment and outside factors.

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