Chromatography Forum

First,
sorry for the broad title, but I have two problems which may or may not be related.
Brief background, this GC 6890 was (as far as I know) in working condition and used sparingly. I just moved here and added an autosampler to the GC. I am having two problems which I am guessing are related.

The "not ready" light is always on before a run. Occasionally I will get an error saying "front inlet pressure not ready". I check the GC's screen for front inlet parameters and compare these numbers to that of the method on the computer, and they match and are stable. Gas Save mode is off... and I have changed the septa and checked the liner, o-ring, etc. and made sure everything on the injector is tightened down. I have even tried switching between split/splitless hoping something would make the system happy, with no luck.

when setting up a sequence, I will "run sequence" and the computer screen will quickly move through some commands and then while "synchronizing" it will abort to the method screen with the "front inlet pressure not ready" as its error

Here is what confuses me... On the methods screen, I can click the big tab with the picture of the Gc vial, and input my sample information, click "start run" and the autosampler will inject the single sample (no sequence, just vial 1) and the "not ready" light will turn off and the system seems fine?!?!

Am I overriding the pressure problem this way? Is there a pressure problem in your opinion?

I am also afraid I may have some parameters in my method which makes the system unhappy. Here they are:

Inlet: 250 C
Psi-9.43
flow-54.2mL
Purge flow to split vent - 50 mL/min @ 2 min

Column: initial oven temperature = 50 C
I am in Constant flow mode
flow - 1.6
Average Velocity - 32

Do any of these conflict... like the flow? what would be the proper values to run this...

I also ran a standard back to back to see if the column flow was different, thus different retention times and they were identical.

I feel like I have tried everything and am desperate. I thank you all in advance for reading this lengthy post.

labratbdf,

Not sure about your front inlet not ready problem, but the other one I might help with. Go to the config button, scroll down to instrument and press enter. Make sure that AUTP PREP RUN is on. This might fix the not ready problem. This, if I understand it right is the same as pushing the PREP RUN button the make the GC come ready. Hope this helps,

Regards,
Mark

Just to be sure...is the autosampler selected in the method that you
are trying to run with your sequence?

I am not sure if the sampler is the source of problem. However, in my past experience i had, the message usually indicate that the pressure in your system is unstable.

Try to see if there is a leak anywhere, you can follow the agilent's guide to detect the leaks in yoru inlet.

Or, if you are lucky enough, just turn the valve on higher on your gas tank.

Thanks for the help everyone... I greatly appreciate it. It is still in the works, but looks like it is a variety of problems. I don't think there is a leak though, but it works (for the most part).

thanks

Hi
You did not mentioned the column you are using. if you use equal to or wider then 0.53mm then you must increase the pressure at the inlet to the GC, or may be you have a problem with the EPC then contact the technical support.
Good luck