Chromatography Forum

Hello, I have an Agilent 6890 GC with an auto sampler. Randomly, after the run finishes while the oven is cooling down, the auto sampler will grab the next vial in the sequence and prepare to inject. This is pretty much a waste of a run because the oven is still cooling down and the peaks all look like garbage. Has anybody experienced this before? Due to the random nature of it, I think the part that is supposed to give a "not ready" signal is failing but I'm not sure where that might be.

Hello

Try procedure below (GC keypad):

1. Press the [Config] key to view a list of configurable parameters
2. Scroll to the Instrument parameter and press [Enter]
3. Scroll to Auto prep run and press [On].

It should help.

Regards

Tomasz Kubowicz

it also varies depending on which software set you are using but it could also be you don't have a long enough Final time at the end of your ramp (for the cool off).

or you could have the final ramp up to temp last for a while and have your final time be your cool period.

also, changing (lengthening) the equilibrium time at the beginning of the run can resolve this. if your injector temperature doesn't change this early injection may not effect your recovery or separation.

if you do injection pre-rinses on your syringe you can also increase the rinses to delay when it injects (i would call this a last resort since it is wasteful).

this depends on your computer software determining the run times on the by and large too. if your GC exclusively sets runs as set by the buttons i'm unsure where to progress to next.


KDM

thanks for the replies, I followed the instructions posted by Tomasz and it seems to be working fine again. Thanks so much!