Why Do Tof Mass Spectrometers Have Unlimited m/z Range?

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Discussion Overview

The discussion revolves around the capabilities of time-of-flight (TOF) mass spectrometers, specifically addressing why they are perceived to have an unlimited range of mass-to-charge (m/z) values for analysis. The scope includes theoretical aspects, practical applications, and comparisons with other mass spectrometry techniques.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant questions the unlimited m/z range of TOF mass spectrometers and seeks a definitive explanation.
  • Another participant suggests that the topic may be better suited for a physics or engineering forum, indicating a potential lack of analytical chemistry expertise in the current forum.
  • A different participant expresses skepticism about the original question being homework but encourages the poster to engage with the topic more deeply.
  • One participant provides specific m/z ranges for quadrupole mass detectors and ion traps, contrasting them with TOF mass spectrometers.
  • There is a discussion about the relationship between mass and instrument output signals, particularly the advantages of TOF mass spectrometry in terms of measuring time of flight compared to Dempster-type mass spectrometry.
  • A participant reflects on the simplicity of measuring time of flight to determine mass, expressing curiosity about the workings of TOF mass spectrometers used in their pharmaceutical company.
  • Clarification is provided regarding Dempster-type mass spectrometers, which utilize magnetic fields to bend flight paths.
  • The original question is reiterated, with an additional comment on the practical challenges of using TOF mass spectrometers in a lab setting.

Areas of Agreement / Disagreement

Participants express varying levels of familiarity with mass spectrometry techniques, and while there is a shared curiosity about TOF mass spectrometers, no consensus is reached regarding the reasons for their unlimited m/z range or their practical advantages compared to other types of mass spectrometers.

Contextual Notes

Participants reference specific m/z ranges for different mass spectrometry types, but the discussion lacks detailed mathematical derivations or assumptions that could clarify the claims made. The practical challenges of using TOF mass spectrometers are mentioned but not elaborated upon.

gravenewworld
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Why is it that time of flight mass spectrometers have basically an unlimited range of m/z values that they can analyze? I have looked, but can not find a definitive answer.
 
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Maybe this can be moved to a physics or engineering forum since it seems we don't have any analytical chemists?
 
This looks suspiciously like homework. Maybe it is, and maybe it isn't. If it is, we do want to see you take a stab at it. If it isn't, I, at least, still want you to take a stab at it.

What are the relationships between mass and instrument output signals for TOF and other types of mass spectrometry?
 
Homework no, curiosity yes. If this were homework it probably would have been overdue by now. What I do know about mass spec

-m/z range <2000 for quadrapole mass detector
-m/z range for quad. ion-trap is <6000

I know m/z for TOF can be calculated by t^2/(d^2/2Ve)
 
Mass is proportional to "time of flight" squared. Compared to "mass is proportional to the inverse of the accelerating potential" for a Dempster type mass spec, do you see any advantages when you consider the resolutions and uncertainties in measurements of time and electric potential?
 
Ah why didn't this hit me over the head before? You only have to measure the time it takes for a substance to travel a fixed distance with fixed potential. Then you can simply find m.

Dempster type mass spec

I am not familiar with this type of mass spec.

BTW, the reason I asked this question is because we have TOF mass specs at the pharm company where I work (I do medicinal chem). I just always wondered how they worked. I assume they use them to measure proteins etc. since they usually have large mws.
 
"Dempster" is the beast that bends flight paths through a magnetic field.
 
Why is it that time of flight mass spectrometers have basically an unlimited range of m/z values that they can analyze? I have looked, but can not find a definitive answer.
certainly not the best of the mass spectrometers in relevance to precision and accuracy;currently on a lab session based of TOF, it's not the most convenient instrument to use of the mass spectrometers.
 

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