AS mangles syringe plungers

[MichaelVW]

I'm doing PCB testing on an 8890 with a G5413A tower, using a Hamilton 1701 syringe.

About once a week, the plunger gets pulled out of the syringe gets destroyed. I think maybe the syringe gets clogged and the syringe can't be forced down into it, or it gets pulled out too far somehow.

These are hexane extracts from all kinds of gross wastes (oils, paints, etc), cleaned up using florisil, acid, silica gel, etc. I'm using hexane and then hex/ace to rinse several times before and after each injection.

Any suggestions?

[TCCrab]

Try changing the syringe rinse solvents.
I've seen toluene react with extracts and physically glue the plunger inside the syringe barrel, causing the plunger to be "Z'd" during the syringe cleaning or during the injection phase.
On the PreInjection phase, we rinse the syringe first with toluene, then with Nonane.
Post injection we rinse the syringe with Nonane first, toluene afterward.
The Nonane seems to act as a lubricant, we've not had stuck syringes in a very long time.

As far as the syringe plunger being withdrawn completely out of the syringe barrel, I don't think it's possible for the autosampler to withdraw the plunger far enough to physically come out of the syringe barrel.

TomC
"Crabs"