Chemstation Sequence Stopping around 6:30 pm

[ChromJoe]

We have a Agilent 7890A GC with a G1888 headspace sampler attached. We are using MSD Chemstation E.02.02.1431, on a Windows 7 PC. The PC is not connected to any network. We've had the instrument for about 1 year and started experiencing issues in March of this year.

So initially chemstation would give us an error about "swap files" which we solved by upgrading the RAM from 2 gb to 4 gb.

Now the sequence running will stop everyday around 6:30 pm. The error log tells us "Job stopped prematurely. GC run aborted. Sequence aborted. Ready for new sequence." We've tried making new methods and running a HDD defrag, but that hasn't helped.

We've been running a 37 vial test run whenever we change something to try to fix the problem. The results are as follows:

8/8/12 - Run started 2:04 PM, stopped at 6:22 PM on vial 16
8/9/12 - Run started 9:53 AM, stopped at 6:19 PM on vial 31
8/13/12 - Run started 11:51 AM, stopped at 6:22 PM on vial 24

Also on 8/2/12 we ran from 7:40 AM to 1:47 PM (23 vials) with no problems for an unrelated project.

I'm not sure if anyone has had similar problems, but any help would be greatly appreciated. I come from an empower background so I'm still learning the chemstation software.

[Don_Hilton]

Hmmm... Reminds me of an instrument problem that occured about that time each day. It was a differnt failure and it was a total mystery until someone was working late and noticed one of the cleaning crew dragging a floor scrubber down the hall and plugging the power cord for the floor scrubber into the row of outlets also being used to power the GC/MS that was failing.

There was a change in outles available to the cleaning crew and the problem went away.

So, given that time is significant, it may be a problem with the instrument environment.

[ChromJoe]

Thanks for the advice, I'll have to double check the instrument environment.

Yesterday (8/14/12) I stayed to watch the error occur. I observed that the GC was on its prerun stage (as it should be) while the headspace is equilibrating, but the “Not Ready” light on the GC stayed on. The GC did not become ready in time for the headspace injection which caused the run to stop at 6:23 PM on Vial 8.

I tried immediately starting another run and had the same issue on vial 2 (GC was ready for vial 1, injected fine, but not 2). I then tried modifying the method to add more time on the headspace sampler for total GC time, going from 16 min to 20 min. Unfortunately the same problem occurred with the GC stopping on vial 2.

I am starting another run now to see if the instrument will run fine again for a while.

[GasMan]

It seems odd that the GC always stops at about the same time of the day. Can you check if there is a clock table entry that somebody may have entered into the GC.

Gasman

[Consumer Products Guy]

Does the room cooling shut down then?

[R13]

Does the room cooling shut down then?

I would second that. Actually the air conditioning might stop at 6 and after the first GC oven cooling down cycle the room temperature increases which makes GC cooling/ equilibration longer.

Is Your method initial column temperature something like 30- 35 C? Does the "another project" method which works OK use higher initial oven temperature?

[ChromJoe]

Thanks everybody for your help. It was a cooling issue. The problem has been solved. Here's an update:

I stayed late 8/29/12 to watch the GC, I noticed something that I should have seen a while ago. The GC wasn’t becoming ready because the oven could not get back down to its initial temp. The initial temp for the run we’ve been testing with is 30°C, the oven could only get to about 31°C. It turns out that at night our AC turns off and we bring in outside air. The room gets into the upper 20°Cs most summer nights. The oven is unable to cool to 30°C when it’s that warm in there. It makes more sense when you consider that I had two good runs last week on cool nights. I ran last night with the initial temp set to 40°C and there were no issues. I plan to do some more tests to be 100% sure, but the instrument is running fine now.

I find it odd that our facilities lets the lab get that warm at night (also humid). That seems like a recipe for disaster for lab work. I'll have to find a way to convice them that it's worth cooling the lab overnight. Anyway, thanks again.

[Consumer Products Guy]

Does the room cooling shut down then?

I would second that. Actually the air conditioning might stop at 6 and after the first GC oven cooling down cycle the room temperature increases which makes GC cooling/ equilibration longer.

Is Your method initial column temperature something like 30- 35 C? Does the "another project" method which works OK use higher initial oven temperature?

Winner, winner - chicken dinner !!! For CPG and R13 !!!

[JMcK]

Being an analytical chemist is like being a detective. Just less murder, hopefully.