PAHs with GC/MS

[Rolkizz]

I am trying to make calibration table of EPA610 (2000-100 ug/ml), but having some problems. I injected manually 1ul (splitless mode) to GC/MS and analyzed it. On second run I made split mode (1:10) of 1ul injection. Comparing the obtained chromatograms (splitless and split), the peak heights are near identical, responses as well. Analyzing 1ul in split mode (1:25), I got higher responses than ones of 1:10 split. So I am wondering what a heck? Is there a problem of manuall injection or the operator (me) is dumb?
I think that lowering the concentration I have to get lowered responses as well, or not?

[Peter Apps]

Manual injections are a learned skill - and not the kind of thing that you can learn from typed forum posts. Getting someone who knows how to show you and critique your technique is the best way, but maybe you can find video instruction on the web.

Dilute solutions will give smaller peaks than concentrated ones provided everything is working as it should.

Peter