Chromatography Forum

I run a 6890 GC with dual injectors and I run with Cool on column injection. I have a reoccurring problem with injection errors. The injector will go down into the column to make the injection but will seem to get stuck and will not make the injection and not pull back up. This will then stall the sequence and give me a syringe error. The error message will give me the option to abort the injection which I will. The syringe will pull back up and continue on the sequence. Most of the time the error will not happen again but sometimes it will continue to happen. I have tried everything, reinstalling the column, changing syringes, changing septas and inserts, cleaning the injector, having the injector sent away for maintenance. The problem will go away for months then come back and no single change seems to fix it. Anyone else have this problem?

What model injector are you using?

7683B autosamplers. I have dual injectors and it happens on both. I can switch the injectors and most of the time the problem stays with the injector but not always sometimes it will stay on the back regardless of which injector is installed.

Hi

Have you tried cleaning the metal guides which the syringe assy moves up and down on? These can get quite dusty / dirty. Also carryout the alignment procedure, instructions are in the manual.
Also I have seen issues with bits of septa which build up in the inlet ( under the septa ) which restricts movement, again this is rare and on very dirty inlets. Best way is to check manually with a syringe.

Good Luck

Thanks, I have tried all of those things. I have also noticed bits of septa in the insert and do clean those regularly and often replace the inserts. These things do sometimes help the problem go away but it always returns despite my best efforts.

Could be a bad belt (flat spots) or motor. When you had it sent it out for service were they checked and/or replaced?