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

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SUMMARY

Time-of-flight (TOF) mass spectrometers possess an effectively unlimited m/z range due to their operational principle, which relies on measuring the time it takes for ions to travel a fixed distance under a constant electric potential. This method allows for mass calculations based on the square of the time of flight, distinguishing TOF from quadrupole and ion trap mass spectrometers, which have limited m/z ranges (e.g., <2000 for quadrupole and <6000 for ion trap). The simplicity of measuring time over distance under fixed conditions contributes to the TOF's broad applicability in analyzing large biomolecules, such as proteins, in pharmaceutical settings.

PREREQUISITES
  • Understanding of mass-to-charge ratio (m/z) in mass spectrometry
  • Familiarity with time-of-flight (TOF) mass spectrometry principles
  • Knowledge of quadrupole and ion trap mass spectrometers
  • Basic physics of motion and electric potential
NEXT STEPS
  • Research the operational principles of TOF mass spectrometers
  • Study the differences between TOF and Dempster-type mass spectrometers
  • Explore the applications of TOF mass spectrometry in protein analysis
  • Learn about the limitations and advantages of various mass spectrometry techniques
USEFUL FOR

This discussion is beneficial for analytical chemists, pharmaceutical researchers, and anyone interested in the principles and applications of mass spectrometry, particularly in the context of protein analysis and large biomolecule characterization.

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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