Lecture 5: Fundamentals of Mass Spectrometry: Hardware

Question 1

what are the components of the mass spectrometer?

Answer 1

inlet, source, analyser, ion detector, data system

Question 2

what does the ion source produce?

Answer 2

ions of the analytes

Question 3

what does the analyser do?

Answer 3

analyzer manipulates the ions according to their mass-to-charge (m/z) ratio.

Question 4

what does the detector system do?

Answer 4

The detector system detects the ions and records the relative abundance of the ion species.

Question 5

If the ion source for gas sample what can it be?

Answer 5

Electron Ionization (EI)				
Chemical Ionization (CI)

Question 6

what the common liquid ion source?

Answer 6

Electrospray Ionization (ESI)

Question 7

what happen with gas sample ionisation?

Answer 7

Not just an ion being formed there will be a charge.

Question 8

what are two types of ionisation?

Answer 8

hard and soft

Question 9

what are hard ionisation techniques ?

Answer 9

Electron Ionisation (EI)

Question 10

what produces more fragments hard ionisation techniques soft?

Answer 10

hard produces more

Question 11

soft ionisation techniques are what?

Answer 11

Chemical ionisation (CI), Fast Atom Bombardment (FAB), Electrospray ionisation (ESI)

Question 12

what better for determining molecular mass, soft or hard?

Answer 12

soft ionisation techniques

Question 13

How does electro ionisation work?

Answer 13

• Molecules are ionized during collision with a beam of high energetic electrons
• Electrons are “boiled off” in a filament

Question 14

what energy is the beam in electron ionisation?

Answer 14

(typical 70 eV energy)

Question 15

EI is great for finding the?

Answer 15

identification of structures

Question 16

what does the high internal energy during EI equal?

Answer 16

Due to high internal energy high degree of fragmentation (which occurs IN ion source)

Question 17

with EI what do u get?

Answer 17

mass spectrum

Question 18

CI: what are the 3 common reagents gases?

Answer 18

Methane (CH4), iso-butane or ammonia (NH3)

Question 19

CI: Electron bombardment of reagent gas produces what?

Answer 19

reagent ions

Question 20

CI: Each gas has a ______ proton-affinity (PA) with the molecule

Answer 20

different

Question 21

In mass spec _____ things happen.

Answer 21

unusual

Question 22

how is a reagent ion made?

Answer 22

the gas has a proton added

Question 23

what is chemical ionisation useful for?

Answer 23

Useful in determination of the molecular ion (don’t know what fragments we have)

Question 24

what ions can be tested?

Answer 24

you can only analyse either positive or negative ions, not both together , positive more common

Question 25

CI: what if a compound does not accept a proton?

Answer 25

hydrogen would donate on because it owns accept,

Question 26

what happen sin ammonia is a reagent gas in CI?

Answer 26

- form radical cation -forms with another ammonia molecule (NH4+) -donates proton to molecule, returns back to ammonia - or may donate the entire nh4+ to the molecule (depend son affinity of compound) - can lead to two

Question 27

in chemical ionisation what will change?

Answer 27

molecular mass, because proton or NH4+ is added to your compound

Question 28

if methane gas in CI?

Answer 28

add proton , mass increase by 1

Question 29

compounds with a low proton affinity have a proton?

Answer 29

taken away

Question 30

in CI negative ions may form but we do not?

Answer 30

measure them , focus on positive ions

Question 31

In EI the repeller should be ?

Answer 31

positive to look at positive ions

Question 32

when is API used?

Answer 32

when we have. liquid sample

Question 33

what are the two types of Atmospheric pressure Ionization ?

Answer 33

ESI | APCI

Question 34

ESI is a ___ technique.

Answer 34

soft

Question 35

(API)'s are useful for what?

Answer 35

useful for the analysis of large non-volatile chargeable molecules such as proteins and nucleic acid polymers.

Question 36

what gas is around the capillary in ESI?

Answer 36

high stream of gas, nebuliser , creating spray or mist.

Question 37

why does ESI require a spray?

Answer 37

smaller droplets, easy to evaporate solvents

Question 38

How do we get rid of solvent molecules in ESI?

Answer 38

there is a heated area allowing the solvent to evaporate, the sis easier with fine droplets form the spray

Question 39

in ESI the entire ESI is put through what volt?

Answer 39

high voltage around 400.

Question 40

what does the high voltage in ESI do?

Answer 40

charge the solvent, proton gets added to analyse, ending in a charge analyte.

Question 41

How do we separate ions?

Answer 41

using a mass analyser

Question 42

what are the types of mass analysers?

Answer 42

Quadrupole (Q) Ion Trap (IT) Time-of-Flight (TOF) Magnetic sector instruments

Question 43

what mass analyser are we focusing on?

Answer 43

Quadrupole (Q)

Question 44

what happens in the quadruple?

Answer 44

it has 4 separate rods with a space in the middle