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TOF Mass Spectrometers

  1. Nov 29, 2005 #1
    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.
     
  2. jcsd
  3. Dec 1, 2005 #2
    Maybe this can be moved to a physics or engineering forum since it seems we don't have any analytical chemists?
     
  4. Dec 1, 2005 #3

    Bystander

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    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?
     
  5. Dec 1, 2005 #4
    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)
     
  6. Dec 1, 2005 #5

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    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?
     
  7. Dec 2, 2005 #6
    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.

    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.
     
  8. Dec 2, 2005 #7

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    "Dempster" is the beast that bends flight paths through a magnetic field.
     
  9. Dec 2, 2005 #8

    GCT

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    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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