Talk:Gas chromatography

Wiki Education Foundation-supported course assignment

This article was the subject of a Wiki Education Foundation-supported course assignment, between 19 January 2021 and 27 April 2021. Further details are available on the course page. Student editor(s): Amassey1. Peer reviewers: Maskewmo, MaryGrace J. Larsen.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 22:04, 16 January 2022 (UTC)

Most common detectors???

I disagree that TCD is the most common GC detector. FID (from my experience) seems to be the general standard for most basic analyses... any thoughts? Blckdmnd99 18:59, 16 May 2006 (UTC)

You are absolutely correct. No way is a TCD the most common detector, I would say without a doubt a FID is the most common, *maybe* followed by ECD. This entire article is rather poorly put together, however somebody has been making some pretty decent contributions recently. I was going to sit down and spend some time working on this, but I have been pretty busy at work, ironically enough, developing GC and GC/MS methods. Babbles 01:35, 19 May 2006 (UTC)

In my experience the FID is most common followed CLOSELY by the TCD. In our lab, we use the TCD extensively to detect water, which of course an FID absolutely CANNOT do, and glycols. —The preceding unsigned comment was added by 65.4.100.235 (talk) 23:40, 24 April 2007 (UTC).

I think it depends on what industry (or research area) to which you're accustomed. In my experience, TCDs are more common than FIDs--but I understand that my experience is just a narrow slice of the world of gas chromatography. I think the problem is that GC is a huge field and it's tough to do it justice in one article. I think we need more sub-articles that go into the details.

But anyway, I agree that the bit about TCDs being the most common should be re-written. If I find the time, I may change it to list both FIDs and TCDs being common, since they both have broad capabilities, with the rest of the detectors being for more specific analyses. Pi3832 11:53, 22 May 2006 (UTC)

Apparently, I found the time. Pi3832 13:18, 22 May 2006 (UTC)

Excellent, thanks! I too am plagued by too much GC / GC/MS time but really want to start getting more involved around here. It's amazing what can happen when everyone pulls their effors together! Blckdmnd99 15:53, 2 August 2006 (UTC)

Well done! The confusion in the beginning may have stemmed from the TCD being commercially available before the FID in the 1950's and thus having been the "first" detector. --Carboxen 05:25, 18 August 2006 (UTC)

Column length

wat happens when the column length is increased -- (msg from December 2004) — Preceding unsigned comment added by 62.252.64.14 (talk) 03:10, 8 December 2004‎ (UTC)

Advantages to increasing column length include better separation of peaks that overlap slightly. Disadvantages are peak spreading and longer retention times. --206.194.127.112 (talk) 20:14, 16 May 2008 (UTC)

The article states that packed columns can be up to 10m long but I used a packed column that is 12m... 148.177.1.215 (talk) 15:43, 22 December 2008 (UTC)

need drawings

It would be excellent if someone came up with drawings for this article. After all, "a picture is worth a thousands of words." Allentchang 00:14, 15 Dec 2004 (UTC)

Added the diagram. Would appreciate some feedback to improve it. -- Rune Welsh ταλκ 21:25, July 13, 2005 (UTC)

I'm an engineer for a manufacturer of GCs and detectors. I'll look through our expired patents and see if I can find anything useful to add on. Rune, your drawing hits pretty well on the concept anyway, that's how I illustrate it when I explain it to people :-) --Eigenvalue 05:08, 2 January 2007 (UTC)

misc additions

Added some more links to manufacturers and added hydrogen to the list of carrier gases. - Babbles 23:00, 24 September 2005 (UTC)

I'm thinking this thing needs an overhaul, I don't think it does a decent job of addressing various things such as column phases, length, diameter, film thickness, injector port, retention time, solvents, Gaussian peaks, solvent/Grob effects and so forth. - Babbles 23:19, 24 September 2005 (UTC)

But I don't think this main article should be too technical. It should be aimed at people who don't atually run GCs, but are interested in them for some other reason. (This is why I added the "GCs in Popular Culture" section.)

Sub-articles that address the kinds of technical details you mention would be A Good Thing, however. Pi3832 11:57, 22 May 2006 (UTC)

I think it would be great to see a little more discussion on temperature programs and software used in GC analysis. (Yes, I say this because I'm struggling with setting up a GC at work and can't seem to find much on information.) jz

What issues are you having? One possible online resource could be: http://www.chromatographyforum.com/ I do not post there and don't really keep up with it, but perhaps it could help you out some. Babbles 17:20, 2 October 2005 (UTC)

For the pop culture references, I'd like to add a reference, but I'm not sure how to merge it with the current text, which is less about the references to GC's and more criticism of its use in pop culture. Here's my reference: In the novel "Zodiac" by Neal Stephenson, the protagonist Sangamon Taylor relies on a GC to do his vigilante environmental detective work. --MM 22:03, 23 June 2006 (UTC)

Another often remembered popular misconception of what GCs can do is Sean Connery's 15-minute complete GC analysis of a cancer drug in the movie "Medicine Man" (1992). Great jungle lab. I would beleive a Helium/TCD analysis of atmospheric gases on a Molsieve column, or a CFC analysis, in that time, not one of a pharmaceutical compound. --Carboxen 05:35, 7 July 2006 (UTC)

History section

The history section is in desperate need of an overhaul. Fuzzform 19:24, 06 Dec 2005 (UTC)

Chromatography Article

The Chromatography article has all of two sentences about GC. And they aren't even entirely correct. Anyone want to volunteer to go edit/expand that? Pi3832 15:38, 22 May 2006 (UTC)

fg/s

I have seen the sensitivity of chromatographs expressed in fg/s. Can someone explain what this measure is please. Lumos3 22:29, 22 May 2006 (UTC)

Femtograms per second. See the metric system article. Pi3832 16:19, 23 May 2006 (UTC)

Methods

I've added a section on Methods, in which to discuss some general information on method developement. If it gets too detailed we may want to make a separate article(s), but I think this is a good place too start. Please, please, please feel free to compose stuff for this section--the subsections, especially.--Pi3832 14:33, 7 June 2006 (UTC)

recent revision of article

Heya all, I have reordered the article a bit a few days ago, to make it be more organized. Various great sections had sprouted recently and it became a collection of subsections without much order (I am not innocent), that I thought distracted from the big picture. Let me know if there are any such changes you disapprove of. Also, volunteers are sought for the sections Data Reduction and analysis (software, integrators, retention indices, databases, mass fragmentograms, etc) and Column selection (phases, dimensions) - I wouldnt mind collaborating. Carboxen 00:57, 22 October 2006 (UTC)

External Links

Not including external links for vendors on this page is fairly clearly covered in the WP:External links guideline. Links to be avoided #4: "Links to sites that primarily exist to sell products or services."

Links to help sites, I feel, fall under the Important points to remember part of the WP:External links guideline. Specifically:

1. Links should be kept to a minimum.
2. Rather than creating a long list of external links, editors should consider linking to a related category in the Open Directory Project (also known as DMOZ) that is devoted to creating relevant directories of links pertaining to various topics. (See {{Dmoz}}.) If there is no relevant category, you can request help finding or creating a category by placing {{Directory request}} on the article's talk page.

DMOZ already has a category for Gas Chromatography, and I have put a link to it in the article.

If there is some external link that can be included within the WP:External links guideline, and explanation on this page would help to keep it from being removed from the article. Thanks. --Pi3832 18:24, 12 March 2007 (UTC)

Too much detail, not enough info in intro for laymen

Hi -- this article bears the marks of TMCGS (Too Many Chemistry Grad Students). It's highly technical and detailed in its topic coverage, but the introduction doesn't even explain in a simple way *what GC is used for*. Perhaps this could be worked on? -- YACGS (yet another chemistry grad student) —The preceding unsigned comment was added by 66.240.10.170 (talk) 03:32, 16 April 2007 (UTC).

HPGC

Sometimes "HPGC" is used. Should it be mentioned in the article, or redirected? — DIV (128.250.204.118 06:53, 11 July 2007 (UTC))
And "HPGLC". — DIV (128.250.204.118 06:55, 11 July 2007 (UTC))

Deleted section on propane and propane accessories

We really don't need a section that does nothing more than list the makers of gas-liquid chromatography equipment and gas-liquid chromatography accessories. It is not encyclopedic, and it is a magnet for spam. --Jaysweet 21:33, 13 July 2007 (UTC)

I see people re-spamming the hell out of this article without justifying on the talk page why those external links are encyclopedic. They are not. I am blanking it again until someone please justifies themselves on the talk page. --Jaysweet 14:30, 19 July 2007 (UTC)

Whoopsies, it appears I've been a little heavy-handed... Most of those links were internal wiki-links and therefore do not qualify as spam. I restored the sections and the internal links. The external links have been removed, though, and I will continue to aggressively remove them. Repeated adding of spam could result in warnings and blocks. --Jaysweet 14:59, 19 July 2007 (UTC)

Separation of components of air

I want the picture present in 9th cbse NCERT book. Can you please help me?? —Preceding unsigned comment added by 125.62.100.167 (talk) 04:52, 12 October 2007 (UTC)

GCs in popular culture

This section sounds very opinionated. — Preceding unsigned comment added by 35.9.128.119 (talk) 21:36, 18 February 2014 (UTC)

"In the U.S. TV show CSI, for example, GCs are used to rapidly identify unknown samples. "This is gasoline bought at a Chevron station in the past two weeks," the analyst will say fifteen minutes after receiving the sample." Is this SO unreasonable? Some GC programs are fast, and given gasoline is volatile, no reason why this should not be. GCs tend to be repeatable; no need to do more than one trace (when it goes to court you might want to, but that can be done later, once the detectives have gone). The "heat out" should be done afterthe previous sample, not just before this one. Are you sure hey are not using GC-MS? They are common on TV (not sure about CSI). Is it possible the analyst has been told in advance to expect a gasoline sample, and has loaded the program already. Once that is done, put the sample in the vial, push the button, and wait for the answer.

Totally different issue: The GC is mentioned in a Simpson's episode. Bart's classmate Martin tells the clas about his hero, the guy who invented the GC. Later in the episode, a GC is used to analyse a "flaming moe". [1] F2Andy (talk) 15:02, 14 January 2008 (UTC)

As a side note regarding the same passage, episodes of CSI only rarely have solid markers of the flow of time in them. "Fifteen minutes" appears, thus, to be a complete guess. The show also has a few meta-jokes about how tests that take hours to days only occupy about thirty seconds of screen time, but that's neither here nor there. Point is, complaining about too-fast analysis on a show that's not meant to be a 24-style minute-by-minute account is mildly ridiculous. Since I'm an anonymous I'm not going to take it out myself, but unless there's a strong counter-reason (or even a citation) I'd think someone should, no? 69.29.95.100 (talk) 14:32, 25 January 2008 (UTC)

I am currently working on this article and as no one has given an argument as to why this section should stay, nor added any citations to the existing section, I will be removing it from the article. It gives the reader no benefit to understanding gas chromatography itself and the information does not come from reliable sources and does seem to be biased. Amassey1 (talk) 12:34, 18 March 2021 (UTC)

Sources?

I think the information here is quite reliable but no source material is stated. Could the author/authors maybe look them up and write them? Would mean a lot since I need to qoute this for an important project. —Preceding unsigned comment added by 83.183.74.61 (talk) 12:53, 18 January 2009 (UTC)

i find thhis data to be wrong  :/ —Preceding unsigned comment added by 148.197.214.196 (talk) 13:46, 2 December 2009 (UTC)

Requested move

The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the move request was: Page moved. Ucucha 02:19, 15 March 2010 (UTC)

---

Gas-liquid chromatography → Gas chromatography — This article is about gas chromatography[2]. Gas-liquid chromatography is a particular kind of gas chromatography where the stationary phase is a liquid on a solid support.[3] (as opposed to gas-solid chromatography[4] or bonded stationary phases [5] - see also Rotzsche, Harald (1991). Stationary phases in gas chromatography. Amsterdam: Elsevier. ISBN 0-444-98733-9.). The current conetents of the gas-liquid chromatography should be moved over redirect to gas chromatography. Kkmurray (talk) 17:44, 7 March 2010 (UTC)

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Technique of FGC

• http://scholar.google.com.hk/scholar?as_q=flash+gas+chromatography&num=10&btnG=Search+Scholar&as_epq=&as_oq=&as_eq=&as_occt=title&as_sauthors=&as_publication=&as_ylo=&as_yhi=&as_sdt=1.&as_sdtp=on&as_sdts=5&hl=en

--222.67.205.143 (talk) 05:24, 31 March 2010 (UTC)

• • Flash pyrolysis - http://scholar.google.com.hk/scholar?as_q=flash+pyrolysis+gas+chromatography&num=10&btnG=Search+Scholar&as_epq=&as_oq=&as_eq=&as_occt=title&as_sauthors=&as_publication=&as_ylo=&as_yhi=&as_sdt=1.&as_sdtp=on&as_sdts=5&hl=en
  • Flash heater - http://scholar.google.com.hk/scholar?hl=en&q=allintitle%3A+%22flash+heater%22+chromatography&btnG=Search&as_sdt=2000&as_ylo=&as_vis=0
  • Flash exchange - http://scholar.google.com.hk/scholar?hl=en&q=allintitle%3A+flash+exchange+chromatography&btnG=Search&as_sdt=2000&as_ylo=&as_vis=0

--222.67.205.143 (talk) 05:59, 31 March 2010 (UTC)

Main section

As I understand it, fractional distillation can be configured in a plant as a continuous process, whereas, at least as I have always seen it implemented, gas chromatography, because of its analytic task, is alwasy a batch process. This is an important distinction, as well, which I feel should be mentioned. —Preceding unsigned comment added by 50.46.82.18 (talk) 14:48, 6 April 2011 (UTC)

It sure is a pretty fine line between an analytical technique and a separation process. Industrial "chromatography" often does involve continuous process however. "All you have to do" is keep track of each bit of injected material and watch the eluent at known times (or distances) from the injection. I haven't seen promotional material for large-scale Simulated moving bed gas chromatography equipment, but there are primary-literature studies of the idea. DMacks (talk) 15:11, 6 April 2011 (UTC)

ERROR CORRECTION AND UPDATE

I have changed this sentence ... FROM

"The atomic emission spectra is diffracted by a diffraction gradient and detected by a series of photomultiplier tubes." TO ...

"The atomic emission spectra is diffracted by a diffraction grating and detected by a series of photomultiplier tubes or photo diodes." To correct an error and to include a more recent technology. SUPERHETRODYNE (talk) 20:16, 6 March 2015 (UTC)

Thanks. Materialscientist (talk) 22:36, 6 March 2015 (UTC)

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Detectors section

I suggest adding the olfactometric detector to this section, and adding an article on gas chromatography-olfactory (GC-O).

Gas chromatography-olfactometry (GC-O) is a technique that integrates the separation of volatile compounds using a gas chromatograph with the detection of odour using an olfactometer (human assessor). While GC separates and quantifies volatile compounds from an extract, human olfaction detects the odour activity of each eluting compound. In this olfactometric detection, a human assessor may qualitatively determine whether a compound has odour activity or describe the odour perceived, or quantitatively evaluate the intensity of the odour or the duration of the odour activity. The olfactometric detection of compounds allows the assessment of the relationship between a quantified substance and the human perception of its odour, without instrumental detection limits present in other kinds of detectors.

The apparatus consists of a gas chromatograph equipped with an odour port (ODP), in place of or in addition to conventional detectors, from with human assessors sniff the eluates. The odour port is characterised by its nose-cone design connected to the GC instrument by a transfer line. The odour port is commonly glass or polytetrafluoroethylene. It is generally placed 30 – 60 cm away from the instrument, extending from the side such that it is not affected by the hot GC oven. The deactivated silica transfer line is generally heated to prevent the condensation of less-volatile compounds. It is flexible so that the assessor can adjust it according to their comfortable sitting position. As traditional warm and dry carrier gases may dehydrate the mucous membrane of the nose, volatiles are delivered via auxiliary gas or humidified carrier gas, with relative humidity (RH) of 50 – 75%, to ease the dehydration.

The olfactometric detector may be coupled with, or connected in parallel to, a flame ionization detector (FID) or mass spectrometer (MS). Moreover, multiple odour ports may be set-up. In these cases, the eluate is generally split evenly between the detectors to allow it to reach the detectors simultaneously.

References