EI- Mass Spectrometry

Question 1

experimental design

Answer 1

blast sample with high energy e- -> through magnetic field -> detector measures particles

Question 2

what kind of particles reach detector

Answer 2

only cations or cationic radicals

Question 3

reaction of molecule

Answer 3

blasted with 70 eV beam of e- -> radical cation formed -> fragmentation to produce most stable fragments

Question 4

what is the base peak

Answer 4

the fragment with the highest abundance (therefore, most stable)

Question 5

alpha cleavage

Answer 5

loss of H radicle to form C-X bond (usually C-O bond)

Question 6

McLafferty rearrangement fragmentation pathway

Answer 6

carbonyl containing compounds with a H at the gamma position; hydrogen atom jumping to the other fragment as a part of the process of the bond breaking

Question 7

what impacts the intensity of signal

Answer 7

stability of cation (more stable = stronger signal)

Question 8

stability of fragment impacting further fragmentation

Answer 8

the more stable the fragment, the less likely to further fragment