Editing Chemical ionization (section)

==Advantages and limitations==
One of the main advantages of CI over EI is the reduced fragmentation as noted above, which for more fragile molecules, results in a peak in the mass spectrum indicative of the molecular weight of the analyte. This proves to be a particular advantage for biological applications where EI often does not yield useful molecular ions in the spectrum.<ref name=":6" /> The spectra given by CI are simpler than EI spectra and CI can be more sensitive<ref name=":0" /> than other ionization methods, at least in part to the reduced fragmentation which concentrates the ion signal in fewer and therefore more intense peaks. The extent of fragmentation can be somewhat controlled by proper selection of reagent gases.<ref name=":1" /><ref name=":6" /> Moreover, CI is often coupled to chromatographic separation techniques, thereby improving its usefulness in identification of compounds.<ref name=":3">{{Cite journal|last=Byrdwell|first=William Craig|date=2001-04-01|title=Atmospheric pressure chemical ionization mass spectrometry for analysis of lipids|journal=Lipids|language=en|volume=36|issue=4|pages=327–346|doi=10.1007/s11745-001-0725-5|issn=0024-4201|pmid=11383683|s2cid=4017177 }}</ref> As with EI, the method is limited to compounds that can be vapourized in the ion source. The lower degree of fragmentation can be a disadvantage in that less structural information is provided. Additionally, the degree of fragmentation and therefore the mass spectrum, can be sensitive to source conditions such as pressure, temperature, and the presence of impurities (such as water vapour) in the source. Because of this lack of reproducibility, libraries of CI spectra have not been generated for compound identification.<ref name=":6" />