WikiProject Physics (Rated Start-class, High-importance)
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WikiProject Mass spectrometry (Rated Start-class, High-importance)
This article is within the scope of WikiProject Mass spectrometry, a collaborative effort to improve the coverage of Mass spectrometry on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start  This article has been rated as Start-Class on the project's quality scale.
High  This article has been rated as High-importance on the project's importance scale.
Comments Please leave a short summary to explain the ratings and to identify the strengths and weaknesses of the article.

## WikiProject class rating

This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 10:02, 10 November 2007 (UTC)

Shouldn't this article contain explanation of saddle potential and how Earnshaw theorem means you can't create a potential minimum. So saddle potential is used and effectively spun to keep ion in trap. —Preceding unsigned comment added by 138.251.248.238 (talk) 16:47, 4 January 2008 (UTC)

## Equations of motion

I started a new section following the discussion in March, R (1997). "An Introduction to Quadrupole Ion Trap Mass Spectrometry" (PDF). J Mass Spectrom. 32 (4): 351–369.. A discussion of mass selective instability, etc. is still needed. --Kkmurray (talk) 20:15, 6 May 2008 (UTC)

I'm sorry - equation 3 looks wrong still. The mass appears only on the first term. The dimensions of the first term are force, while those of the second are just position. My edit resulted from a straightforward substitution of (2) into (1), and caused the units to agree. Please justify equation 3. —Preceding unsigned comment added by 146.6.180.188 (talk) 19:03, 27 October 2009 (UTC)

## Impenetrable?

I'm inclined to agree (and sadly, the same could be said of many of the wikipedia mass spectrometry pages), but there is also much useful material here. Personally, I feel the article would be greatly improved by the addition of an "Introduction", which should cover roughly what a simple 3d trap looks like, and the saddle-shaped potential well inside, and how when this is spun, an ion is trapped. It might also be worth describing how it is used in a typical MS or MS/MS application. I'd be happy to have a go at this if anyone approves, but it will involve tinkering with the existing text a little, as different introductory comments tend to appear in dribs and drabs at the moment. Any feedback welcome Lionelmh (talk) 16:52, 20 July 2009 (UTC)

This article definitely needs some overhaul, starting with the introduction. The theory section doesn't even start by mentioning anything about a quadrupole field. Equations of motion are given, but I think it's too much derivation, not enough qualitative explanation. I feel that only a rough sketch of the EoM is necessary, and interested readers can look up the references of which there are many (and a lot are listed on this article, one thing it is good at). I agree with Lionelmh that adding some applications for examples would be good. I'm willing to work on improving the introduction and theory sections. mvd (talk) 18:15, 28 October 2010 (UTC)
The illustration looks quite nice, but the AC (RF) source and its connections are disproportionately tiny; the artist who created the image needs to learn some basics of illustrating. Far worse, although this might be a cross-section, the description implies that the axis of the ring is vertical. Showing only a cross-section (if that's what it is) of a structure that is very unfamiliar to many readers only obfuscates. Are the top and bottom electrodes shaped like round plano-convex lenses? A perspective illustration of the electrodes (and, ideally, equipotential surfaces) would clarify the structure a great deal.
This reminds me of discussions of bipolar transistors where the structure is represented by by three rectangles of ideally-equal height, side by side, for the emitter, base, and collector. However, the term "base width", instead of "base thickness" seems to be universal, as if one's sense of reality were confined to A.K. Dewdney's Planiverse (or Flatland). It's as if one cuts a bologna sandwich into two pieces, then looks at the cut edge and refers to the width instead of the thickness of the bologna. This illustration surely seems to represent an equivalent failure to represent in three dimensions. Nikevich (talk) 08:35, 15 December 2011 (UTC)

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