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2nd year sem 1: spectroscopy and advanced analysis > Lecture 5: Fundamentals of Mass Spectrometry: Hardware > Flashcards

Lecture 5: Fundamentals of Mass Spectrometry: Hardware Flashcards

1
Q

what are the components of the mass spectrometer?

A

inlet, source, analyser, ion detector, data system

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2
Q

what does the ion source produce?

A

ions of the analytes

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3
Q

what does the analyser do?

A

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

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4
Q

what does the detector system do?

A

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

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5
Q

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

A 
Electron Ionization (EI)				
Chemical Ionization (CI)
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6
Q

what the common liquid ion source?

A

Electrospray Ionization (ESI)

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7
Q

what happen with gas sample ionisation?

A

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

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8
Q

what are two types of ionisation?

A

hard and soft

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9
Q

what are hard ionisation techniques ?

A

Electron Ionisation (EI)

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10
Q

what produces more fragments hard ionisation techniques soft?

A

hard produces more

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11
Q

soft ionisation techniques are what?

A

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

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12
Q

what better for determining molecular mass, soft or hard?

A

soft ionisation techniques

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13
Q

How does electro ionisation work?

A
  • Molecules are ionized during collision with a beam of high energetic electrons
  • Electrons are “boiled off” in a filament
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14
Q

what energy is the beam in electron ionisation?

A

(typical 70 eV energy)

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15
Q

EI is great for finding the?

A

identification of structures

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16
Q

what does the high internal energy during EI equal?

A

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

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17
Q

with EI what do u get?

A

mass spectrum

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18
Q

CI: what are the 3 common reagents gases?

A

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

19
Q

CI: Electron bombardment of reagent gas produces what?

A

reagent ions

20
Q

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

A

different

21
Q

In mass spec _____ things happen.

A

unusual

22
Q

how is a reagent ion made?

A

the gas has a proton added

23
Q

what is chemical ionisation useful for?

A

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

24
Q

what ions can be tested?

A

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

25
Q

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

A

hydrogen would donate on because it owns accept,

26
Q

what happen sin ammonia is a reagent gas in CI?

A
  • 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
27
Q

in chemical ionisation what will change?

A

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

28
Q

if methane gas in CI?

A

add proton , mass increase by 1

29
Q

compounds with a low proton affinity have a proton?

A

taken away

30
Q

in CI negative ions may form but we do not?

A

measure them , focus on positive ions

31
Q

In EI the repeller should be ?

A

positive to look at positive ions

32
Q

when is API used?

A

when we have. liquid sample

33
Q

what are the two types of Atmospheric pressure Ionization ?

A

ESI

APCI

34
Q

ESI is a ___ technique.

A

soft

35
Q

(API)’s are useful for what?

A

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

36
Q

what gas is around the capillary in ESI?

A

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

37
Q

why does ESI require a spray?

A

smaller droplets, easy to evaporate solvents

38
Q

How do we get rid of solvent molecules in ESI?

A

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

39
Q

in ESI the entire ESI is put through what volt?

A

high voltage around 400.

40
Q

what does the high voltage in ESI do?

A

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

41
Q

How do we separate ions?

A

using a mass analyser

42
Q

what are the types of mass analysers?

A

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

43
Q

what mass analyser are we focusing on?

A

Quadrupole (Q)

44
Q

what happens in the quadruple?

A

it has 4 separate rods with a space in the middle

2nd year sem 1: spectroscopy and advanced analysis (5 decks)

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