Editing Electron ionization (section)

==== Analysis of archaeologic materials ====
Direct insertion electron ionization mass spectrometry (direct insertion EI-MS) has been used for the identification of [[archeology|archeological]] [[adhesive]]s such as tars, [[resin]]s and [[wax]]es found during [[Excavation (archaeology)|excavations]] on archeological sites. These samples are typically investigated using gas chromatography–MS with extraction, purification, and derivatization of the samples. Due to the fact that these samples were deposited in [[Prehistory|prehistoric]] periods, they are often preserved in small amounts. By using direct insertion EI–MS archaeological samples, ancient organic remains like [[pine]] and [[pistacia]] resins, birch bark tar, [[beeswax]], and plant oils as far from [[Bronze Age|bronze]] and [[Iron Age]] periods were directly analyzed. The advantage of this technique is that the required amount of sample is less and the sample preparation is minimized.<ref>{{Cite journal|last1=Regert|first1=Martine|last2=Rolando|first2=Christian|date=2002-02-02|title=Identification of Archaeological Adhesives Using Direct Inlet Electron Ionization Mass Spectrometry|journal=Analytical Chemistry|language=en|volume=74|issue=5|pages=965–975|doi=10.1021/ac0155862|pmid=11924999}}</ref>

Both direct insertion-MS and gas chromatography-MS were used and compared in a study of characterization of the organic material present as coatings in [[Roman Empire|Roman]] and Egyptian [[amphora]]s can be taken as an example of archeological resinous materials. From this study, it reveals that, the direct insertion procedure seems to be a fast, straightforward and a unique tool which is suitable for screening of organic archeological materials which can reveal information about the major constituents within the sample. This method provides information on the degree of oxidation and the class of materials present. As a drawback of this method, less abundant components of the sample may not be identified.<ref name=":1">{{Cite journal|last1=Colombini|first1=Maria Perla|last2=Modugno|first2=Francesca|last3=Ribechini|first3=Erika|date=2005-05-01|title=Direct exposure electron ionization mass spectrometry and gas chromatography/mass spectrometry techniques to study organic coatings on archaeological amphorae|journal=Journal of Mass Spectrometry|language=en|volume=40|issue=5|pages=675–687|doi=10.1002/jms.841|pmid=15739159|issn=1096-9888|bibcode=2005JMSp...40..675C}}</ref>