Sample run time

[rachstar]

I work with an agilent GC for TPH analysis. I'm new to working with it but have noticed the analysis has slowed down. It used to run approximately 3 samples per hour but now I'm lucky if it does 2.

Is there a reason for this? Or is it just due to oven cooling taking too long between samples?

Got a busy workload so could do with it performing 3 per hour!

Any advice/reassurance would be appreciated

[bisnettrj2]

Has anything changed since it ran three samples per hour? New column? Different GC method parameters? How long has it been since you were able to run three samples per hour? Was it a sudden or gradual change?

[scottythree]

If your room is running hotter then normal then the oven may be taking longer to cool. I've seen this in my lab in the summer time. You may want to take a look at the back of the gc and make sure the flapper door is opening sufficiently to expel the heat. If it isn't you probably have a weak or dead flapper motor.

[rachstar]

Nope nothing has changed, same column and parameters. Just the past week it has started to slow. Was having problems with inlet pressure today - the septum needed changed so perhaps that is related?

Checked the back of the GC and it seemed to be fine for expelling the heat.

I'll see in the morning how it has done overnight!

[Steve Reimer]

If the pressure won't stabilize the GC won't go to a ready state and start the injection.