Mass Spectrometry (Alternate Ionization)

Question 1

ESI (Definition)

Answer 1

Electron Spray Ionisation

Produces ions using an electrospray in which a high voltage is applied to a liquid to produce an aerosol

Question 2

ESI (Scheme)

Answer 2

Spraying nozzel –Taylor Cone–> Analyte Molecule (Charged Parent Droplet) –Solvent Evaporation–> Charged Droplet at Rayleigh limit –Column to fission–> Charged progeny droplets -> Naked Charged Analyte

Question 3

MALDI (Defintion)

Answer 3

Matrix Assisted Laser Desorption/Ionization

Question 4

MALDI-ToF (Definition)

Answer 4

Uses laser energy absorbing matrix to create ions from large molecules with minimal fragmentation

Question 5

MALDI-ToF (Advantages)

Answer 5

Rapid, accurate cost effective (microbial characterisation and identification)

Question 6

MS/MS (Scheme)

Answer 6

Draw on nearest piece of paper available and check against notes

Question 7

Collision Induced Fragmentation (Uses)

Answer 7

Used for structural investigation
Chooses a primary fragment ion: M1 - > M2+
Further fragmentation: M2+ + C -> M3+
Can choose collision energy and collision partner to maximise info obtained

Question 8

Metastable Ions (Problem)

Answer 8

Causes asymmetric peak shapes for ToF applications

Non-integral ,ass peaks in double focussing instruments