Solution level in vial - GC needle height

Discussions about GC and other "gas phase" separation techniques.

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Hi ,

We have Agilent 7890B with 7693 Autosampler
Struggling with sample < 0.5ml
How much is required to go into vial ?
ie how far does GC needle go into vial as default setting?
mm away from bottom of vial ?

Currently using standard 2ml vial

I don't want to mess with sampling offset


for Agilent 7693A Variable sampling depth –2 to +30 mm above default
so you can check it.

If your sample is less than 0.5ml isn't it better to use vial with insert?


Tomasz Kubowicz

by that rationale the needle sits 2mm above bottom of vial when taking a sample ?

Inserts were next option by don't have any available at the moment
3mm is the standard needle depth. Setting the option to -2mm means taking 1mm from the bottom of the vial.
0.5ml should be plenty for a standard vial. One definitely does not want to fill all the way up !

Sometimes we used small-volume vials which had more glass and a cone-shaped inside, so similar to using a separate insert. But most times we had plenty of sample solution so not a common issue in our business.
5 posts Page 1 of 1

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