Talk:Gas chromatography–mass spectrometry

Cleanup and revision

I started to redo quite a bit of this article. I felt while some things were not necessarily incorrect, they seemed as if they could be misleading. Furthermore what I felt was important information was totally missing from this article.

Babbles 04:52, 24 July 2007 (UTC)

What does this need before it can be removed from cleanup? Please list here and' on the WP:LO page. Thanks! JesseW 23:54, 19 Oct 2004 (UTC)

--Mmcdougall 16:29, 13 May 2005 (UTC)

Main page is getting pretty close to "ready-to-go" I think. The redacted information (now at the bottom of the talk section), should not be lost. We should find a more appropriate home for it. Similarly, there is detail in that section that should be pushed to CG and MS sections. Sentor material should be editted and moved to Sentor.

I just read this article for the first time in a long time and I think it looks much better, but it still needs some work. Should probably add a section about pharmaceutical and/or bioanalytical methods. I personally feel the section about Full Scan vs SIM is a bit misleading if not somewhat incorrect. If it is worth anything I have been running GC & GC/MS instruments for ~8 years now and I'll try to put my two cents in but that entire time thing is restrictive at times.

Babbles 01:12, 24 July 2007 (UTC)

Other comments

"Law Enforcement

GC-MS is increasingly used for detection of illegal narcotic, and may eventually supplant drug-sniffing dogs."

Anybody have some solid information on this? While there are some quasi-portable GC's that can be taken into the field (they put one on the Mars rover), there are most certainly not hand portable units. Additionally there are certain factors like instrument maintenance, run times, and quality control which makes it unlikely that it would replace a drug sniffing dog. At least not in the near future.

Babbles 01:27, 24 July 2007 (UTC)

Okay, so I admit, it's a bit chatty. It's based on a paper I wrote for a scientic evidence class. It's really just talking about how GC/MS works and what its strengths and limitations are. So there's really nothing that's specific to Scientific Evidence, except towards the end when it starts talking about how it functions under certain legal tests, but that's still relevant.

--Jvraba 10:20, 21 Jul 2004 (UTC)

Okay, so I've started to seperate the legal discussions under seperate headings. The article used to have tons of footnotes, so if things seem like they pop out of nowhere, they might need to be fixed. Actually maybe someone has a better article to adapt for this purpose. But I think it's pretty useful.

--Jvraba 06:30, 23 Jul 2004 (UTC)

If you create a new section, try to use the equal-sign convention (two equals signs for a headline, three for a subhead, four for a sub-sub-head) so it's added to the table of contents rather than just bolding.

Salasks 14:13, 23 Jul 2004 (UTC)

This article has a lot of legal information I was unaware of, but it needs work by someone more familiar with GC/MS. In particulat, I think it poorly describes the technique. One problem with the paper is that it repeatedly refers to mass spectrography. Should be "spectrometry". Cool Hand Luke 23:24, 28 Sep 2004 (UTC)

I'll put a link to the original paper. This version takes out all the footnotes, obviously. Some things which may seem like poor or superficial descriptions may be the product of depending on a footnote that is no longer there. I have no problem with this thing being quite gutted. And maybe I should excerpt the paper to address the legal implications of GC/MS and leave the rest to real scientists. As far as spectrography / spectrometry, it seems to be used interchangibly in certain literature, although this may reflect an artificate of certain periods of development. I began the paper with huge footnotes on the history of GC and MS, so maybe this had a lasting effect on my style throughout.

--Jvraba 03:01, 17 Oct 2004 (UTC)

Actually, I think I was too harsh on this article. I think it'll require a lot of work, but all of this legal information is actually a very good thing. Although it probably needs to be reorganized and made less verbose, I think most of this information is appropriate. I would imagine lots of folk in chemical sciences would find the article interesting just for the legal aspects of a familiar technique. Unfortunatly, I don't have very much time to work on it now. Cool Hand Luke (Communicate!) 08:29, 17 Oct 2004 (UTC)

The article shows some promise - I have added links to the text but that in itself took me an hour. It needs de-essaying and things like "needle in a haystack" need to come out. I reckon it would make a really good article if you removed the half of the content that was making it too verbose. I will continue to edit it over the next few weeks, but it will take many revisions as it's too much to do in one go. It probably needs about 10 hours work in total. GregRobson 20:23, 30 Nov 2004 (UTC)

Proposed introduction

I'm willing to do the cleanup. It will take me quite an effort to eliminate all the wordy "deadwood" in this article. Could the original author provide references so that it will be easier for me to rephrase parts of the article? Allentchang 08:21, 23 Nov 2004 (UTC)

That's great that you are willing to work on cleaning this up. I assume you've asked at the Talk page of the first contributor(see History)? JesseW 10:31, 23 Nov 2004 (UTC)

I sent Mr. Chang the artciel. I believe he's working on it now. As a lawyer, I was a bit "cliff's notes" in my understanding of the underlying science, although I tried to do my best to go through all the seminal journal articles. Some things which sound like omissions in the text above are actually nuanced or more clearly explained in the footnotes. Anyway, it seemed like a good idea at the time. But if it doesn't work out, I'm all for completely gutting this entry and starting over again. --Jvraba 02 Dec 2004

I'll get the cleanup done before Christmas. My background is in electrical engineering, but I've editted technical articles before. allentchang 21:56, 11 Dec 2004 (UTC)

Legal implications section

The latter third of this article about the implications of GC/MS and related technologies in the American legal system is very interesting. In fact I thought it must have been copied from somewhere else becaue it was very clearly written not as a Wikipedia article. However it seems the author has put it here so it's legit. However, I think it doesn't really fit on this page. I think there should be a page on scientific evidence in the legal system, and this section can serve as the foundation of that article. I'm not going to move it or anything, I just wanted to provide my thoughts and how best to organize this information. I don't think the legal stuff should stay on this page in the current level of detail, but we should keep it somewhere else and link to it. Nohat 00:53, 16 Dec 2004 (UTC)

Probably true. Well, before I pasted in my article there was no GC/MS article, and people kept asking me about GC/MS, so I figured it was better than nothing. I know there are certain problems with the article as it currently stands, because obviously, especially towards the end, its analytical framework is from the scientific evidence (legal) point of view. Was it originally written as a Wiki article? No. It was originally written as a term paper. But it seemed generalized enough to be useful. One of the problems it had, is that some of the more specific scentific quibbles remained in the footnotes which I did not paste in. Allentchang, who is currently working on the article, has the version complete with footnotes. I'm actually looking forward to seeing this reworked. --Jvraba 19:32, 18 Dec 2004 (UTC)

The university library where I'm checking several sources on the subject is closed for winter break so it will take me much longer than I had promised. Allentchang 20:24, 24 Dec 2004 (UTC)

Clarify this paragraph

"Alternatively, the single-magnet analyzer chamber will deflect the various particles through an electromagnetic field within a long curved tube. The lighter particles traverse the analyzer tube the fastest. The particles emerge from the magnetic region and strike the detector, transferring its charge. This activates the recorder which takes note of the atomic mass through the mass/charge ratio and evaluates concentration of that molecule contained in the sample."

Please clarify the above paragrapgh. So how exactly does the single-magnet analyzer discriminate between particles of different mass to charge ratios? I've read websites that suggest that single magnet is tunned to allow particles of a certain mass to charge ratio to be able to complete the journey through the long curved tube. Particles with a different mass to charge ratio has a trajectory that is incompatible with the pathway offered by the long curved tube and therefore these particles collide on the wall of the tube. Allentchang 20:59, 24 Dec 2004 (UTC)

I invite anyone to cleanup sections after MS components

I invite anyone to cleanup sections after MS components. There's already a complaint that this article is more than 32k. There are sections of the article after MS compennts that I cannot properly clean up without consulting the book by Giannelli, Paul C. and Imwinkelried, Edward J. The UC Berkeley library does not have that book for some reason. Allentchang 22:43, 7 Jan 2005 (UTC)

GC/MS analysis

I've looked at the section on GC/MS analysis and got very confused. You said that two kinds of analysis are possible: comparative and original. You then proceed to explain about the comparative analysis in the first paragraph. Then in the second paragraph you vaguely mention about "another analysis." Is this other analysis the "original analysis"? If not, then there is no where in your GC/MS section that talks about original analysis.

Additionally, you later mention "full spectrum" analysis and selective ion monitoring. It seems to me that you are talking at most five different types of analysis instead of two: "comparative," "original," "another," "full spectrum," and "selective ion monitoring." Allentchang 22:54, 7 Jan 2005 (UTC)

Ruthlessly Excised sections for clarity

Heres the original bits.

See http://www.chemistrydaily.com/chemistry/Gas_chromatography-mass_spectrometry - the rest cut per WP:C --Kkmurray 02:18, 15 June 2007 (UTC)

GC/MS Analysis

Would anyone object to a section in the GC/MS page focusing on some practical observations from someone who works in a lab that does both environmental analysis and drug detection work? We tend to be very focused on supporting the identification with various kinds of quality control samples to show the system is working. We are also always up against the concept of "detection limit". Non-technical clients can't get over the idea that we can't say a sample does not contain a given compound. The best we can do is say we saw no reliable signal above the detection limit. The second question is always "How much is in there?", so quantitation should probably get a mention.

My suggestion?

I'd add a sentence like "GCMS has a very low detection limit, and can be used to determine how much of blah-de-blah is is present, unlike such-and-such. Then I'd put my insights re: quality controls ect in the detection limit article. Sadly, I'm not an expert on GCMS, so I can't make the "true" statements in good faith.

If you know about these machines, please help with a related article

See HHO gas. A scientist by the name of Ruggero Santilli wrote a journal paper claiming a new gas based on electrolysis of water with all kinds of "anomalous properties" like not obeying the normal gas laws and having a different amount of energy in different circumstances. Most of his evidence is in the form of spectrometry scans, like a scan showing a peak at 5 amu and one showing monoatomic oxygen that "can only be explained" by his pet fringe theory of physics, etc. Can someone familiar with these devices help me out? Look over the paper (in the References section) and the graphs and point out any:

• Glaring errors (there are several typos and incorrect units in the paper)
• Internal inconsistencies (why do the same scans of the same compound look so different from each other?)
• Obvious misinterpretations of the graphs (is there normally a peak for monoatomic oxygen because of the electrical dissociation in the spectrometer?)
• Areas that would have to be looked into further to determine the validity of these tests or other places these claims would likely be responded to

— Omegatron 15:04, 8 June 2007 (UTC)

new sections: split/splitless and purge and trap

Just added two new sections. Not sure if they should be independent sections or part of 'Instrumentation'. Anyway, I need to add references but most of the info is from training materials not available to the public (I am a GC-MS operator). I will be making articles about Purge and Trap GC-MS when I get chance. Also I think we should standardise the form we express GCMS. In this article the forms GC/MS and GC-MS are both in use.

Tangaloomaflyer 11:12, 10 October 2007 (UTC)

Technical Error on Page

This page, as it stands, should be koskoskoksoksoko GC-scanning MS.

As this topic relates to both GC and MS, it is important to bear in mind that there is a page dedicated to Mass Spectrometry, where most Mass Spectrometers are described.

A scanning mass spectrometer looks at 1 ion at a time and throws away the rest. It then moves onto the next ion. If one looks at it critically, one will see that a SCAN is just a very long and sequential SIM.

A Time-of-Flight Mass Spectrometer does not "scan". It records complete "snapshots" or spectra, not throwing away any masses.

This has 2 implications: 1) A TOFMS cannot do SIM. 2) A TOFMS provides you with more accurate repesentations of the GC peaks.

By claiming that SIM is more sensitive than SCAN, one also assumes that one is looking at a smaller number of ions under SIM than under SCAN. This last claim is a very difficult one to make, especially if one considers TOFMS instruments as included under "SCAN".

A TOFMS can be just as sensitive as other Mass Spectrometers running under SIM. This has been shown over and over by TOFMS users. It really does depend on whether one does 1 ion SIM (nice to show off SIM, but useless in real life) or whether one does 3+ ions SIM (Retention Time + 3 ions seems to be the bare minimum for positively identifying chemicals). At 3 ion SIM level, a TOFMS is often just as sensitive.

12:53, 11 November 2007 (UTC)

A triple collector IRMS doesn't scan. GraemeLeggett 10:38, 12 November 2007 (UTC)

Gas chromatography-mass spectrometry (GC-MS) is a method that combines the features of gas-liquid chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC-MS include drug detection, fire investigation, environmental analysis, explosives investigation, and identification of unknown samples. GC/MS can also be used in airport security to detect substances in luggage or on human beings. Additionally, it can identify trace elements in materials that were previously thought to have disintegrated beyond identification.

The GC-MS has been widely heralded as a "gold standard" for forensic substance identification because it is used to perform a specific test. A specific test positively identifies the actual presence of a particular substance in a given sample. A non-specific test, however, merely indicates that a substance falls into a category of substances. Although a non-specific test could statistically suggest the identity of the substance, this could lead to false positive identification.

Contents [hide] 1 History 2 Instrumentation 2.1 Split/Splitless GC-MS inlets 2.2 Purge and Trap GC-MS 2.3 Types of Mass Spectrometer Detectors 3 Analysis 3.1 Full Scan MS 3.2 Selective Ion Monitoring 3.3 Types of Ionization 3.3.1 Electron Ionization 3.3.2 Chemical Ionization 3.4 GC-MS/MS 4 Applications 4.1 Environmental Monitoring and Cleanup 4.2 Criminal Forensics 4.3 Law Enforcement 4.4 Security 4.5 Food, Beverage and Perfume Analysis 4.6 Astrochemistry 4.7 Medicine 5 See also 6 References 7 Bibliography 8 External links

[edit] History The use of a mass spectrometer as the detector in gas chromatography was developed during the 1950s by Roland Gohlke and Fred McLafferty.[1][2] These sensitive devices were bulky, fragile, and originally limited to laboratory settings. The development of affordable and miniaturized computers has helped in the simplification of the use of this instrument, as well as allowed great improvements in the amount of time it takes to analyze a sample. In 1996 the top-of-the-line high-speed GC-MS units completed analysis of fire accelerants in less than 90 seconds, whereas first-generation GC/MS would have required at least 16 minutes.[citation needed] This has led to their widespread adoption in a number of fields.

[edit] Instrumentation Main articles: gas chromatograph and mass spectrometer

The insides of the GC-MS, with the column of the gas chromatograph in the oven on the right.The GC-MS is composed of two major building blocks: the gas chromatograph and the mass spectrometer. The gas chromatograph utilizes a capillary column which depends on the column's dimensions (length, diameter, film thickness) as well as the phase properties (e.g. 5% phenyl polysiloxane). The difference in the chemical properties between different molecules in a mixture will separate the molecules as the sample travels the length of the column. The molecules take different amounts of time (called the retention time) to come out of (elute from) the gas chromatograph, and this allows the mass spectrometer downstream to capture, ionize, accelerate, deflect, and detect the ionized molecules separately. The mass spectrometer does this by breaking each molecule into ionized fragments and detecting these fragments using their mass to charge ratio.

GC-MS schematicThese two components, used together, allow a much finer degree of substance identification than either unit used separately. It is not possible to make an accurate identification of a particular molecule by gas chromatography or mass spectrometry alone. The mass spectrometry process normally requires a very pure sample while gas chromatography using a traditional detector (e.g. Flame Ionization Detector) detects multiple molecules that happen to take the same amount of time to travel through the column (i.e. have the same retention time) which results in two or more molecules to co-elute. Sometimes two different molecules can also have a similar pattern of ionized fragments in a mass spectrometer (mass spectrum). Combining the two processes makes it extremely unlikely that two different molecules will behave in the same way in both a gas chromatograph and a mass spectrometer. Therefore when an identifying mass spectrum appears at a characteristic retention time in a GC-MS analysis, it typically lends to increased certainty that the analyte of interest is in the sample.

[edit] Split/Splitless GC-MS inlets Samples are introduced to the column via an inlet. This inlet is typically injection through a septum. Once in the inlet, the heated chamber acts to volatilise (vapourise) the sample. In a split system, a constant flow of carrier gas moves through the inlet. A portion of the carrier gas flow acts to transport the sample into the column. Another portion of the carrier gas flow gets directed to purge the inlet of any sample following injection (septum purge). Yet another portion of the flow is directed through the split vent in a set ratio known as the split ratio. In a splitless system, the advantage is that a larger amount of sample is introduced to the column. However, a split system is preferred when the detector is sensitive to trace amounts of analyte and there is concern about overloading the column.

[edit] Purge and Trap GC-MS For the analysis of volatile compounds a Purge and Trap (P&T) concentrator system may be used to introduce samples. The target analytes are extracted and mixed with water and introduced into an airtight chamber. An inert gas such as Nitrogen (N2) is bubbled through the water; this is known as purging. The volatile compounds move into the headspace above the water and are drawn along a pressure gradient (caused by the introduction of the purge gas) out of the chamber. The volatile compounds are drawn along a heated line onto a 'trap'. the trap is a column of adsorbent material at ambient temperature that holds the compounds by returning them to the liquid phase. The trap is then heated and the sample compounds are introduced to the GC-MS column via a volatiles interface, which is a split inlet system. P&T GC-MS is particularly suited to volatile organic compounds (VOCs) and BTEX compounds (aromatic compounds associated with petroleum).[3]

[edit] Types of Mass Spectrometer Detectors The most common type of mass spectrometer (MS) associated with a gas chromatograph (GC) is the quadrupole mass spectrometer, sometimes referred to as a Mass Selective Detector. Another relatively common detector is the ion trap mass spectrometer. Additionally one may find a magnetic sector mass spectrometer, however these particular instruments are expensive and bulky and not typically found in throughput laboratories. Other detectors may be encountered such as time of flight (TOF), tandem quadrupoles (MS-MS) (see below), or in the case of an ion trap MSn where n indicates the number mass spectrometry stages.

[edit] Analysis A mass spectrometer is typically utilized in one of two ways: Full Scan or Selective Ion Monitoring (SIM). The typical GC/MS instrument is capable of performing both functions either individually or concomitantly, depending on the setup of the particular instrument.

[edit] Full Scan MS When collecting data in the full scan mode, a target range of mass fragments is determined and inputed into the instrument's method. An example of a typical broad range of mass fragments to monitor would be m/z 50 to m/z 400. The determination of what range to use is largely dictated by what one anticipates in being in the sample while being cognizant of the solvent and other possible interferences. A MS should not be set to look for mass fragments too low or else one may detect air (found as m/z 28 due to nitrogen), carbon dioxide (m/z 44) or other possible interferences. Additionally if one is to use a very large scan range then sensitivity of the instrument is decreased due to performing fewer scans per second since each scan will have to detect a wide range of mass fragments.

Full Scan is useful in determining unknown compounds in a sample. It provides more information than SIM when it comes to confirming or resolving compounds in a sample. During instrument method development it may be common to first analyze test solutions in full scan mode to determine the retention time and the mass fragment fingerprint before moving to a SIM instrument method.

[edit] Selective Ion Monitoring In Selective Ion Monitoring (SIM) certain ion fragments are entered into the instrument method and only those mass fragments are detected by the mass spectrometer. The advantages of SIM are that the detection limit is lower since the instrument is only looking at a small number of fragments (e.g. three fragments) during each scan. More scans can take place each second. Since only a few mass fragments of interest are being monitored, matrix interferences are typically lower. To additionally confirm the likelihood of a potentially positive result, it is relatively important to be sure that the ion ratios of the various mass fragments are comparable to a known reference standard.

[edit] Types of Ionization After the molecules travel the length of the column, pass through the transfer line and enter into the mass spectrometer they are ionized by various methods with typically only one method being used as any given time. Once the sample is fragmented it will then be detected, usually by an electron multiplier diode, which essentially turns the ionized mass fragment into an electrical signal that is then detected.

The ionization technique chosen is independent of using Full Scan or SIM.

[edit] Electron Ionization By far the most common and perhaps standard form of ionization is electron ionization (EI). The molecules enter into the MS (the source is a quadrupole or the ion trap itself in an ion trap MS) where they are bombarded with free electrons emitted from a filament, not much unlike the filament one would find in a standard light bulb. The electrons bombard the molecules causing a hard ionization that fragments the molecule, and the way in which a molecule fragment is usually typical for all EI techniques.

[edit] Chemical Ionization Main article: Chemical ionization In chemical ionization a reagent gas, typically methane or ammonia is introduced into the mass spectrometer. Depending on the technique (positive CI or negative CI) chosen, this reagent gas will interact with the electrons and analyte and cause a 'soft' ionization of the molecule of interest. A softer ionization fragments the molecule to a lower degree than the hard ionization of EI. One of the main benefits of using chemical ionization is that a mass fragment closely corresponding to the molecular weight of the analyte of interest is produced.

Positive Chemical Ionization In Positive Chemical Ionization (PCI) the reagent gas interacts with the target molecule, most often with a proton exchange. This produces the species in relatively high amounts.

Negative Chemical Ionization In Negative Chemical Ionization (NCI) the reagent gas decreases the impact of the free electrons on the target analyte. This decreased energy typically leaves the fragment in great supply.

Please help improve this section by expanding it

with: Updating. The following information is in the process of being updated:. Further information might be found on the talk page or at requests for expansion. (September 2007)

The primary goal of instrument analysis is to quantify an amount of substance. This is done by comparing the relative concentrations among the atomic masses in the generated spectrum. Two kinds of analysis are possible, comparative and original. Comparative analysis essentially compares the given spectrum to a spectrum library to see if its characteristics are present for some sample in the library. This is best performed by a computer because there are a myriad of visual distortions that can take place due to variations in scale. Computers can also simultaneously correlate more data (such as the retention times identified by GC), to more accurately relate certain data.

Another method of analysis measures the peaks in relation to one another. In this method, the tallest peak is assigned 100% of the value, and the other peaks being assigned proportionate values. All values above 3% are assigned. The total mass of the unknown compound is normally indicated by the parent peak. The value of this parent peak can be used to fit with a chemical formula containing the various elements which are believed to be in the compound. The isotope pattern in the spectrum, which is unique for elements that have many isotopes, can also be used to identify the various elements present. Once a chemical formula has been matched to the spectrum, the molecular structure and bonding can be identified, and must be consistent with the characteristics recorded by GC/MS. Typically, this identification done automatically by programs which come with the instrument, given a list of the elements which could be present in the sample.

A “full spectrum” analysis considers all the “peaks” within a spectrum. Conversely, selective ion monitoring (SIM) only monitors selected peaks associated with a specific substance. This is done on the assumption that at a given retention time, a set of ions is characteristic of a certain compound. This is a fast and efficient analysis, especially if the analyst has previous information about a sample or is only looking for a few specific substances. When the amount of information collected about the ions in a given gas chromatographic peak decreases, the sensitivity of the analysis increases. So, SIM analysis allows for a smaller quantity of a compound to be detected and measured, but the degree of certainty about the identity of that compound is reduced.

[edit] GC-MS/MS When a second phase of mass fragmentation is added, for example using a second quadrupole in a quadrupole instrument, it is called MS/MS or Tandem MS. Tandem mass spectrometry (MS/MS) is a more powerful technique to quantitate low levels of target compounds in the presence of a high sample matrix background.

The first quadrupole (Q1) is connected with a collision cell (q2) and another quadrupole (Q3). Both quadrupoles can be used in scanning or static mode, depending on the type of MS/MS analysis being performed. Types of analysis include product ion scan, precursor ion scan, Single Reaction Monitoring (SRM) and Multiple Reaction Monitoring (MRM) and Neutral Loss Scan. For example: When Q1 is in static mode (looking at one mass only as in SIM), and Q3 is in scanning mode, one obtains a so-called product ion spectrum (also called "daughter spectrum"). From this spectrum, one can select a prominent product ion which can be the product ion for the chosen precursor ion. The pair is called a "transition" and forms the basis for SRM (MRM if more than one transition is chosen for the precursor ion). MRM is highly specific and virtually eliminates matrix background.

[edit] Applications

[edit] Environmental Monitoring and Cleanup GC-MS is becoming the tool of choice for tracking organic pollutants in the environment. The cost of GC-MS equipment has decreased significantly, and the reliability has increased at the same time, which has contributed to its increased adoption in environmental studies. There are some compounds for which GC-MS is not sufficiently sensitive, including certain pesticides and herbicides, but for most organic analysis of environmental samples, including many major classes of pesticides, it is very sensitive and effective.

[edit] Criminal Forensics GC-MS can analyze the particles from a human body in order to help link a criminal to a crime. The analysis of fire debris using GC-MS is well established, and there is even an established American Society for Testing Materials (ASTM) standard for fire debris analysis. GCMS/MS is especially useful here as samples often contain very complex matrices and results, used in court, need to be highly accurate.

[edit] Law Enforcement GC-MS is increasingly used for detection of illegal narcotics, and may eventually supplant drug-sniffing dogs.[1] It is also commonly used in forensic toxicology to find drugs and/or poisons in biological specimens of suspects, victims, or the deceased.

[edit] Security A post-September 11 development, explosive detection systems have become a part of all US airports. These systems run on a host of technologies, many of them based on GC-MS. There are only three manufacturers certified by the FAA to provide these systems,[citation needed] one of which is Thermo Detection (formerly Thermedics), which produces the EGIS, a GC-MS-based line of explosives detectors. The other two manufacturers are Barringer Technologies, now owned by Smith's Detection Systems and Ion Track Instruments, part of General Electric Infrastructure Security Systems.

[edit] Food, Beverage and Perfume Analysis Foods and beverages contain numerous aromatic compounds, some naturally present in the raw materials and some forming during processing. GC-MS is extensively used for the analysis of these compounds which include esters, fatty acids, alcohols, aldehydes, terpenes etc. It is also used to detect and measure contaminants from spoilage or adulteration which may be harmful and which is often controlled by governmental agencies, for example pesticides.

[edit] Astrochemistry Several GC-MS have left earth. Two were brought to Mars by the Viking program.[4] Venera 11 and 12 and Pioneer Venus analysed the atmosphere of Venus with GC-MS.[5] The Huygens probe of the Cassini-Huygens mission landed one GC-MS on Saturn's largest moon, Titan.[6] The material in the comet 67P/Churyumov-Gerasimenko will be analysed by the Rosetta mission with a chiral GC-MS in 2014. [7]

[edit] Medicine In combination with isotopic labeling of metabolic compounds, the GC-MS is used for determining metabolic activity. Most applications are based on the use of 13C as the labeling and the measurement of 13C/12C ratios with an isotope ratio mass spectrometer (IRMS); an MS with a detector designed to measure a few select ions and return values as ratios.

[edit] See also Liquid chromatography-mass spectrometry Ion mobility spectrometry-mass spectrometry Prolate trochoidal mass spectrometer

[edit] References ^ Gohlke, R. S., Time-of-flight mass spectrometry and gas-liquid partition chromatography. Anal. Chem. 1959, 31, 535-41 ^ Gohlke, R. S.; McLafferty, F. W., Early gas chromatography/mass spectrometry. J. Am. Soc. Mass Spectrom. 1993, 4, (5), 367-371. ^ "Optimizing the Analysis of Volatile Organic Compounds - Technical Guide" Restek Corporation, Lit. Cat. 59887A ^ The Development of the Viking GCMS ^ V. A. Krasnopolsky, V. A. Parshev (1981). "Chemical composition of the atmosphere of Venus". Nature 292: 610–613. doi:10.1038/292610a0. ^ H. B. Niemann, S. K. Atreya, S. J. Bauer, G. R. Carignan, J. E. Demick, R. L. Frost, D. Gautier, J. A. Haberman, D. N. Harpold, D. M. Hunten, G. Israel, J. I. Lunine, W. T. Kasprzak, T. C. Owen, M. Paulkovich, F. Raulin, E. Raaen, S. H. Way (2005). "The abundances of constituents of Titan’s atmosphere from the GCMS instrument on the Huygens probe". Nature 438: 77–9–784. doi:10.1038/nature04122. ^ Goesmann F, Rosenbauer H, Roll R, Bohnhardt H (2005). "COSAC onboard Rosetta: A bioastronomy experiment for the short-period comet 67P/Churyumov-Gerasimenko". Astrobiology 5 (5): 622–631. doi:10.1089/ast.2005.5.622.

[edit] Bibliography Robert P., Dr Adams (2007). Identification of Essential Oil Components By Gas Chromatography/Mass Spectrometry. Allured Pub Corp. ISBN 1-932633-21-9. Adlard, E. R.; Handley, Alan J. (2001). Gas chromatographic techniques and applications. London: Sheffield Academic. ISBN 0-8493-0521-7. Eugene F. Barry; Grob, Robert Lee (2004). Modern practice of gas chromatography. New York: Wiley-Interscience. ISBN 0-471-22983-0. Eiceman, G.A. (2000). Gas Chromatography. In R.A. Meyers (Ed.), Encyclopedia of Analytical Chemistry: Applications, Theory, and Instrumentation, pp. 10627. Chichester: Wiley. ISBN 0-471-97670-9 Giannelli, Paul C. and Imwinkelried, Edward J. (1999). Drug Identification: Gas Chromatography. In Scientific Evidence 2, pp. 362. Charlottesville: Lexis Law Publishing. ISBN 0-327-04985-5. McEwen, Charles N.; Kitson, Fulton G.; Larsen, Barbara Seliger (1996). Gas chromatography and mass spectrometry: a practical guide. Boston: Academic Press. ISBN 0-12-483385-3. McMaster, Christopher; McMaster, Marvin C. (1998). GC/MS: a practical user's guide. New York: Wiley. ISBN 0-471-24826-6. Message, Gordon M. (1984). Practical aspects of gas chromatography/mass spectrometry. New York: Wiley. ISBN 0-471-06277-4. Niessen, W. M. A. (2001). Current practice of gas chromatography--mass spectrometry. New York, N.Y: Marcel Dekker. ISBN 0-8247-0473-8. Weber, Armin; Maurer, Hans W.; Pfleger, Karl. Mass Spectral and GC Data of Drugs, Poisons, Pesticides, Pollutants and Their Metabolites. Weinheim: Wiley-VCH. ISBN 3-527-31538-1.

[edit] External links MeSH Gas+chromatography-mass+spectrometry GCMS Tutorial Gas Chromatography-Mass Spectroscopy Background Introduction to Mass Spectrometry —Preceding unsigned comment added by 122.167.220.84 (talk) 14:24, 10 November 2008 (UTC)

Splitting off Applications

Does anyone have an opinion on whether the applications section could be split off into a page of its own? This article is quite long as it is, and adding more detail about applications (which could easily be done) will only make it more unwieldy. Thoughts, before I take a crack at it? Canada Hky (talk) 00:22, 15 May 2010 (UTC)

Move discussion in progress

There is a move discussion in progress on Talk:Liquid chromatography-mass spectrometry which affects this page. Please participate on that page and not in this talk page section. Thank you. —RM bot 19:30, 18 March 2011 (UTC)

Questionable section

I have removed the following section from the paragraph about Finnigan. If someone can find sources linking Friedman to Finnigan, and integrate this information into the paragraph, that would be helpful. As was, it didn't connect with the rest of the section. Mary Mark Ockerbloom (talk) 21:10, 23 January 2015 (UTC)

"Amongst others, a long time employee of the Finnigan corporation, Lloyd Friedman, ((an Engineer schooled through the Air Force {in the late 60's})), is credited to aiding in the maintenance, improvement, and evolution of the gas chromatograph mass spectrometer" ((Shemesh Friedman / daughter of Lloyd Friedman, and writer of this statement)).

Possible unrelated references

These two references had been added after the reflist, but it's not clear to what statements, if any, they relate. I'm moving them here; if someone can identify a relevant place for their citation, please do. Mary Mark Ockerbloom (talk) 13:28, 24 January 2015 (UTC) 18. Masoum S, Ghasemi-Estarki H, Seifi H, Ebrahimabadi EH, Parastar H. Analysis of the volatile chemical constituents in Mindium laevigatum by gas chromatography — Mass spectrometry and correlative chemometric resolution methods. Microchemical J. 2013;106:276-81. http://www.sciencedirect.com/science/article/pii/S0026265X12001932

19.Masoum, S., Seifi, H., & Ebrahimabadi, E. H. (2013). Characterization of volatile components in calligonum comosum by coupling gas chromatography-mass spectrometry and mean field approach independent component analysis. Anal. Methods. http://pubs.rsc.org/en/content/articlelanding/2013/ay/c3ay40451j#!divAbstract

External links modified

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Introduction is WRONG, WRONG, WRONG!

The begining section needs to be fixed. This sentence is completely wrong. "The use of a mass spectrometer as the detector in gas chromatography was developed during the 1950s after being originated by James and Martin in 1952.[1]" Read the article. The method of detection described in that reference IS NOT a mass spectrometer, it is a titration cell fitted with a photoelectric detector to detect the phenol red in the solution. I don't have time to fix this, and don't know how to edit it properly. I am putting this note here, so, someone with the expertise can fix it. — Preceding unsigned comment added by 155.41.226.36 (talk) 17:21, 23 April 2017 (UTC)

History lead sentence and 2x secondary source refs added. From doi:10.1021/acs.analchem.6b01628 "The invention of gas chromatography is commonly attributed to A. T. James and A. J. P. Martin in 1952 ... The first GC/MS experiments were carried out by Fred McLafferty and Roland Gohlke at Dow Chemical with Bill Wiley and Ian McLaren at Bendix Research Laboratories sometime in the winter of 1955–1956." --Kkmurray (talk) 19:24, 23 April 2017 (UTC)

Needs citations

It seems like this article is lacking citations in several of the major sections. For example, "Types of mass spectrometer detectors," "GC-tandem MS," and the "Analysis" sections have no in-text citations! As a graduate student in chemistry, I really like the information in these sections. But there needs to be citations so people who are less familiar with chemistry can validate the information given. Is anyone willing to take on this task? Any analytical chemistry textbook would probably be a good place to start. Paiges8 (talk) 01:55, 19 January 2018 (UTC)