What is Gas chromatography–mass spectrometry?
[[Image:GCMS closed.jpg|right|300 px|Example of a GC-MS instrument|thumb]] '''Gas chromatography–mass spectrometry''' ('''GC-MS''') combines the features of [[gas-liquid chromatography]] (GC) and [[mass spectrometry]] (MS). This makes it possible to identify different substances within a test sample. GC-MS has many uses include [[drug]] detection, [[fire]] investigation, [[environment]]al analysis and [[explosives]] investigation. It can also be used to identify unknown samples. GC-MS can also be used in [[airport]] security to detect [[substance]]s in [[wikt:luggage|luggage]] or on [[human being]]s. Additionally, GC-MS can identify [[trace element]]s in [[wikt:deteriorated|deteriorated]] materials, even after the sample fell apart so much that other tests cannot work. GC-MS is the best way for [[Forensics|forensic]] experts to identify substances because it is a ''specific test''. A specific test positively identifies the actual presence of a particular substance in a given sample. A ''non-specific test'' only says that categories of substances are in the sample. Although a non-specific test could [[statistic]]ally suggest the identity of the substance, this could lead to [[false positive]] identification. ==History== The first research papers on gas-liquid chromatography were published in 1950. [[Chemist]]s used different [[detector]]s to see that [[chemical compound|compounds]] were flowing out of the end of the chromatograph. Most of the detectors destroyed the compounds, because they [[burn]]ed them or [[ion]]ed them. These detectors left chemists guessing the exact identity of each compound in the sample. In the 1950s, Roland Gohlke and [[Fred McLafferty]] developed a new combined [[machine]]. They used a mass spectrometer as the detector in gas chromatography.<ref>{{Cite journal | doi = 10.1021/ac50164a024 | title = Time-of-Flight Mass Spectrometry and Gas-Liquid Partition Chromatography | year = 1959 | author = Gohlke, R. S. | journal = Analytical Chemistry | volume = 31 | issue = 4 | pages = 535–541}