EI or CI in GC/MS?

[nomadbuck]

Hi All,
My company is buying a GC/MS for residual solvent and extractable/leachable analyses. Does anyone have an opinion on the ionization if both EI and CI are needed, or EI should suffice in most cases?

Thanks in advance.

[jh1]

From my experience working with EI and CI, Negative CI is really useful if you want to look at very low (ppb or lower) levels of halogenated and certain other highly electronegative compounds. If these types of compounds are not of interest to you or you don't need really low LODs for them then EI mode alone will probably be suitable for your needs.


Also, in the case of Agilent's 5975 (possibly other vendors as well) you can always buy the 5975 EI and then pay them later for the CI upgrade.

[Ron]

Residual solvents and leachables are things that need to be legally defensible in most cases, and there are no standard methods for these assays using CI. Unless you are willing to do an extensive validation, I would not recommend being a pioneer.

[nomadbuck]

Again, Thank you for your insight, jh1 and Ron.