Talk:Liquid chromatography–mass spectrometry

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Mass spectrometry (inactive)

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Requested move

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section.

Closed per unanimous opinion. — kwami (talk) 04:26, 16 April 2011 (UTC)[reply]

Liquid chromatography-mass spectrometry → Liquid chromatography–mass spectrometry — Most reliable sources, such as those on Google Books, use either an en dash (it may appear as a hyphen in the search results but if you go look it is actually a dash) or a forward slash. MOS:ENDASH #3 also supports an en dash. The "Spacing" subsection of MOS:ENDASH would argue for the en dash to be spaced since the independent elements "liquid chromatography" and "mass spectrometry" have multiple words, but I have rarely seen this. CWenger (talk) 19:29, 18 March 2011 (UTC)[reply]

Support This is standard punctuation. Spaced en dashes are relatively uncommon, and I don't see that they'd be disambiguating in this context.

Oops. I moved those the other day without seeing the RfM here.

Added a 4th article. Not sure how to punctuate that one. — kwami (talk) 10:15, 25 March 2011 (UTC)[reply]

Support The en dash is certainly required by WP:ENDASH. I agree that the spaced version is not needed here (though currently WP:ENDASH might call for it). A spaced en dash would not help the reader. (Kwami, has the article already been moved? Then this RM needs to be closed, doesn't it?) –_⊥^{¡ɐɔıʇǝo}Noetica!^T– 07:27, 30 March 2011 (UTC)[reply]
Comment LC-MS, GC-MS, CE-MS and similar techniques are sometimes collectively referred to as "hyphenated techniques". --Nick Y. (talk) 13:14, 30 March 2011 (UTC)[reply]

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

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urine analysis ??

"The limitations of LC-MS in urine analysis drug screening is that it often fails to distinguish between specific metabolites, in particular with hydrocodone and its metabolites. LC-MS urine analysis testing is used to detect specific categories of drugs. However, gas chromatography (GC-MS) should be used when detection of a specific drug and its metabolites is required." in definition it suddenly gets into a specific analysis. doesn't fit there.--ArazZeynili (talk) 08:50, 26 March 2012 (UTC)[reply]

History of Ion-mobility spectrometry–mass spectrometry ??

"In 1963 McAfee and Edelson published an IMS-TOF combination. From their Letter to the Editor [1] it is not conclusive whether they used an orthogonal extraction TOF. Most likely it was, because they seem to have used the TOF of the company Bendix, which was an orthogonal TOF." The term "Orthogonal TOF" is used incorrectly. Principle of orthogonal acceleration was first suggested in 1987 http://en.wikipedia.org/wiki/Time-of-flight_mass_spectrometry#Orthogonal_acceleration_time-of-flight and MS devices that utilize this feature are referred to as "Orthogonal TOF" (O-TOF). — Preceding unsigned comment added by Krakozyablic (talk • contribs) 09:44, 19 July 2012 (UTC)[reply]

Section content redacted and placed here, because it was only representative of a narrow area of LC-MS (protein separations)...

... and not the general, complete area indicated by the article title.

PLEASE DO NOT REVERT THIS WITHOUT CAREFUL CONSIDERATION. THE TEXT REMOVED WAS SIMPLY INAPPROPRIATE FOR THIS ARTICLE. I AM A PROFESSIONAL IN THIS AREA.

To replace it, a Wikipedia section from the HPLC article was cribbed and edited to provide a good starting point for future expansion.

Here is the protein-specific text that was removed, if it can be used elsewhere in the article or other articles. LeProf.

"For most protein work, the proteins are first digested into small fragments (say , 5-10 amino acids), separated by HPLC (high performance liquid chromatography), and then run individually through the mass spec. Protein sequencing and older protein identification methods also start with proteolytic digestion Endopeptidases that digest at known sites are used, such as trypsin (cleaves after Lys or Arg) and chymotrypsin (cleaves after Phe, Trp, or Tyr). Ionizing the peptide needs to be done rather gently. One common technique is MALDI (matrix-assisted laser desorption/ionization). The proteins are mixed with the matrix molecules, which efficiently absorb the UV laser energy and encourage ionization of the proteins. When irradiated with the laser, they vaporize along with the protein, but their small size makes them easy to detect and ignore. Time-of-flight mass spectrometry is generally used (so the whole thing is MALDI-TOF). The molecular ions are accelerated in an electric field, and the time it takes them to cross a chamber of known length is proportional to their mass (actually, mass to charge ratio [m/z]). This technique works well for the wide range of sizes seen with peptides. Sample comparisons can be done by labeling one sample with a heavy, stable isotope such as 13C or 15N. The samples are mixed before 2D electrophoresis and they co-migrate on the gel. However, mass spectrometry can easily resolve them." — Preceding unsigned comment added by 50.179.92.36 (talk) 04:14, 7 December 2013 (UTC)[reply]

Lead edited conservatively...

... for clarity, accuracy, consistency. LeProf

Further Lead changes

I've made some slight changes, mostly to clarify. I am not sure what "provides structural identity of the individual components with high molecular specificity" was intended to mean, but have reworded because (1) mass spec doesn't provide structural identity. It provides a lot of useful information, but it's very rarely possible to be 100% sure of the structure. Many isomers with extremely similar structures are very hard to identify by MS alone; complex molecules are difficult to identify by LC-MS alone if you have absolutely no starting point about what they might be, and no library matches. I also felt it necessary to distinguish between the ability to identify unknown peaks de novo, and the ability to confirm the identity of a peak that you know well, and for which you have standards (and can therefore check spectral match as part of routine analysis). And it's important to note that MS provides specificity even if you aren't using the spectral information for anything (for example in MRMs in tandem LC-MS-MS in triple-quads etc.). I didn't want to put too much detail in the lead, but hope it's slightly more clear now.

I'm also going to remove the precise statement of the high vacuum, because different instruments operate at wildly different levels of vacuum. There's more difference between a typical quadrupole and an orbitrap than there is between a typical quadrupole and the atmosphere! We could put some values in, with sources and indications of instrument types, if it's felt go be genuinely helpful, but a one-size-fits-all number with no source didn't seem sensible. Elemimele (talk) 17:33, 19 January 2022 (UTC)[reply]