Mass analysers Flashcards
What are the different types of mass analysers?
Time of flight, orbitrap, ion trap, quarupole, ion cyclotron resonance
What 3 factors are important for mass analysers?
Upper mass limit, ion transmission, resolution
What is ion transmission
Sensitivity
What is resolution?
How good is it at separating ions of similar m/z
How is the quadrupole electrical field obtained?
Application of voltage made up of DC component and RF potential
What are some disadvantages of quadrupoles?
Detects m/z
What are some advantages of quadrupoles
Low cost, rapid scanning, ideal for GC-MS, widely used for ES-MS, low ion transmission
What is sandwich geometry and where is it found
Found in ion trap anaylsers. Electrodes consist rind electrode in the middle with cap electrodes on either end
How is a mass spectrum produced for ion trap?
By scanning RF voltages to eject ions through the end cap
What are higher performance ion traps called?
Linear ion traps
How do TOF analysers separate ions?
Differences in velocity as they move in straight path towards detector
What is the TOF mass range
Unlimited
What is the reflectron used for?
TOF - correct for effects of kinetic energy distributions of ions (longer flight path)
What does the ion mirror do?
Reverses the direction of travel of the ions - ions of higher KE penetrate further therefore have longer flight path
Resolution of linear TOF
