Ion detectors Flashcards
What are the 3 ion detectors?
PM-photomultiplier, EM-electronmultiplier and MCP-micro-channel plate array detectors
How does PM work
Detects photons - ions strike dynode which emits electrons which strike a phosphorous screen. Burst of photons released which pass into multiplier and amplification occurs
How does EM work?
Ions strike dynode which emits electrons. There’s amplification when they strike the next dynode
How does MCP work?
Simultaneous detection of m/z values
What method is usually combined with MS for volatiles?
GC
What is LC combined with MS for?
Polar molecules
What analyser is EI normally used with?
Quadrupole (cheap but low res)
What does EI require the molecules to be like?
Volatile (non-polar and low Mr)
How to analyse volatile compounds?
GC-MS
What analyser is MALDI usually paired with?
TOF (unlimited mass randge)
What is the method of choice for mass fingerprinting e.g. heterochemical and fuel industry?
MALDI-TOF
What analyser is used for ES sources?
Triple quadrupole, ion trap, orbitrap, Q-TOF
What is a hybrid instrument?
2 or more analysers in tandem for MS/MS (e.g. MALDI-TOF/TOF, MALDI-QIT
