GCMS using H2 carrier

fentanyl test.TIF

The extractor source makes more ions - is more sensitive. Etune drives the system to take advantage of the design.  This happens as the repeller is pushing and the extractor is pulling - at least that's how I explain it. Either tune can be used, you just have to understand the pluses and minuses.

The larger hole in the Draw Out/Extractor lens reduces the ionization volume 'pressure'  -- it lets molecules and ions out faster than the smaller holes.  This is important with the many more hydrogen molecules for the same flow than you'd have with hydrogen.  The effect is that it raises the linear range to a higher level.  It does not increase the dynamic range, it gives up some ultimate low end sensitivity to gain higher concentration linearity.

Tailing very, very rarely happens in the source. It is essentially always in the inlet.  I'd have to play with the data file in MassHunter Qual to know for sure, but the little 4.892 and 6.249 peaks are not tailing.   What GC, inlet, inlet injection mode and parameters, liner, injection volume, column, column installed height...all those little things?   

We can go back and forth here if you'd like, but it may be better if you called Agilent and spoke to the Online Technical Support folks who know about applications.  Fentanyl is a tough compound to chromatograph anyway.  How does it look with a boring simple easy non-reactive sample?

Thank you for all your help.