Chromatography Forum

I have a HP 5890 that is currently hooked up to a Tekmar headspace sampler. When I have the detector lit on the 5890 I get the interference seen in the picture below.



I have two 5890s on the same breaker, one has the baseline interference, the other does not. The first thing I did was run a dedicated line to the gc that had the interference. No change in the interference.

I recently installed a zero air generator, I bypassed it using compressed air, my baseline rose and the interference stayed the same.

I leak checked the system, and checked flow rates, and everything looked ok.

Finally I turned on the other 5890 lit the fid, and noticed the interference on the other gc went away. pic below



I checked the outlets and all are grounded correctly. The two gcs are on separate breakers now, but the computers for both gcs are still on the same breaker as the gc that didn't have any interference problems to begin with. I'm going make sure that the computers are both on the same breakers as the gcs they are connected to, if that doesnt work im at a bit of a loss.

Any ideas? Having both gc's on and lit fixes the problem, but it'll drive me nuts not knowing why that is.

You state the following
"Finally I turned on the other 5890 lit the fid, and noticed the interference on the other gc went away. pic below"

If you turn the other 5890 on, turn all the gas flows on to the detector but do NOT light the flame, does the problem go away on the first 5890?

Gasman

What is the time scale ? Unless you have the chart really zipping through it looks more like a gas flow fluctuation than an electronics problem, and that is borne out by the troubleshooting you have done so far.

Peter

Turning the gas on to the other GC does not fix the interference. At first I also thought it was a gas issue, but after switching out generators for tanks, bypassing traps, and leak checking I ran out of ideas. I still need to move the computer that the gc with interference is hooked up to to the same breaker to see if that makes a difference. Until than I have just been making sure that both instruments are running when I need to do an analysis.