Depth of Injection

[Roxanne42]

Just a quick question...

I seem to remember that when we did injections on the GC in my previous lab, we would push the needle all the way into the injection port (until the glass syringe hit the metal)...

In my current lab, we use a CTC-PAL autosampler to do the injections (Agilent 6850 GC)... The needle only goes partly in by default - is this a concern for reproducibility or because we're using an autosampler it's completely irrelevant...?


Thanks!

Roxanne.

[AICMM]

Roxanne42,

Autosamplers are typically very reproducible on sampling depth so this should be irrelavent. On the 5890's there was a heat profile for the injector so sampling depth would affect discrimination. I suspect the same may be true for 6850's so you might try different heights if you need to alter sensitivity or discrimination.

Syringe all the way to the metal nut is also very reproducible, especially for manual injections, which is why I suspect people do it that way.

Best regards.