Suppose I have a GC/MS and I inject a solution containing equal amounts of two substances.
0.0001 mole of compound A, killsyoufast
0.0001 mole of compound B, killsyouslow
Both compounds have roughly the same volatility and both give me good GC peaks, and both have similar behavior in the ion source.
Being an experienced mass spectroscopist, I know that each compound will have its own ionization efficiency.
1. What properties that are intrinsic to the molecules will help me predict ionization efficiency? Size? Cross-sectional area? This or that or another functional group? Electron withdrawing groups? Aromaticity or lack thereof?
2. What is a good reference that explains these factors?
Thank you,
Kevin Olsen
I'll try to get the ball rolling. Both kinetics and thermodynamics affect the ionization efficiency; how easily ionization occurs and how stable the carbocation products are. Lone pairs of electrons, double bond, and aromatics are prime candidates for losing electrons, where as, branched structures and those with resonance structure are thermodynamically favored. So, I expect to observe greater sensitivity for compounds with more of these features.
Hey Kevin, have you take a look at these: Anal. Chem., 2010, 82 (7), pp 2865–2872
DOI: 10.1021/ac902856t; Rapid Commun Mass Spectrom. 2008;22(3):379-84. doi: 10.1002/rcm.3371. Regards.
- Badges
- Science topic
- Similar topics
- Chemistry
- Biochemistry