mass spectroscopy- NMR Flashcards
what are the 4 advantages of mass spectroscopy?
universal detection
gives structural info via mass fragments
high sensitivity
may be coupled to chromographic systems
what is mass spectroscopy based on?
mass to charge ratio(m/z).
how does ionisation occur?
Ionisation -electron is removed from parent molecule by the beam
what is the charge of a radial molecular ion?
+1
is ionisation a hard or gentle technique?
it is a hard technique- causes fragmentation -reproducible
why does fragmentation occur?
excess energy
what happens in fragmentation?
molecule splits- and these fragments are detected by MS
what is ESI?
electrospray ionisation(ESI).
is ESI a hard or soft technique?
it is a soft technique that is integrated with liquid chromatography
what does ESI do?
creates charged molecules while removing the solvent
how can you influence positive ionisation in ESI?
using acidic mobile phase conditions
what happens in ESI if more than one functional group?
the charge may be greater than 1
what is a quadrupole?
4 metal rods - electric charge is applied- mass selective
what is mass spectroscopy- resolution?
allows for discrimination between v similar products
what is the nitrogen rule?
for a neutral atom, made up of the most abundant isotopes present
odd no of atoms= odd MR
even no of atoms= even MR
