PAHs (Polycyclic aromatic compounds)

Its not recommended to change source and and quadrupole temperature. What is mass range of compounds you are trying to analyze? What is your GC injection temperature and oven program?

Hi there, 

You should also look at transfer line temperature which needs to be higher than normal. This link may give some additional ideas on things to try like pulsed splitless
https://www.agilent.com/cs/library/brochures/brochure_pah_food_gc-ms-ms_5994-2016en_agilent.pdf

Do remember to check the temperature limits for your GC and MS as they can vary from model to model
Kevin

Thank you, i am gonna try it

I always question the need for dramatically higher than normal transferline temperatures. The column piece inside is essentially at the full vacuum of the MS and so the boiling points of all compounds are significantly lower.   250°C transferline temperature under vacuum means the atmospheric boiling point of the compound could be 600°C.

That said, It makes some sort of sense to run the transferline at the same temperature as the ion source to help the ion source thermal stability.

Changing the ion source temperature is no problem at all. In fact, most operators should increase it higher than the default 230° C temperature.  I recommend 275°C for most all applications.  That temperature does change the spectral tilt, reducing the 502 abundance somewhat, but increases the amount of time between source cleanings by having more of the source area hotter.

Changing the quadrupole temperature is not a good thing, though. The lifetime is reduced a bit if you run the quad at 200°C all the time.  The default 150°C is fine for all but a very, very few ultra high temperature applications.

Thanks for correction. I also didn't realize this was for heavier PAH's which could benefit from increased temp.