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Flashcards in Into To Mass Spec Deck (14):
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Definition of mass spec

The process of weighing molecules based on the ratio between mass and charge

1

Mass spectrometers are able to

- measure atomic and MW of charged species
- analyse low sample levels
- analyse compounds in mixtures

2

Mass spectrometers are unable to

- detect neutral molecules and radicals

3

Definition if isotope

Atoms of the same element with different numbers of neutrons in atomic nucleus
Add mass but not charge

4

Mass accuracy definition

Half (distance between MW/MW of highest) in ppm

5

Definition of mass resolution

The ability to separate two ion signals from one another in a mass spectrum

6

Basic components of a mass spec

Ion source
Mass analyzer
Ion detector

7

Examples of ion sources

- MALDI
- electrospray ionization

8

Explain MALDI

Matrix assisted laser desorption ionization
- analyte of interest mixed with matrix compound that efficiently absorbs laser wave length
- allows ionization of sample molecules through electron transfer

9

Types of mass analysers

TOF
Quadrupoles
Quadrupole ion trap
Ion cyclotron resonance

10

How does a reflector TOF MS work?

The reflect extends the light tube to almost twice the length
Ions with greater kinetic energy pass further into the reflection before being repelled

11

How does a quadrupole ion trap work?

Ions are trapped in a small interior volume between conical lenses
Raising or lowering the voltages on the entrance and exit trap electrodes controls the movement of ions

12

How does the ion cyclotron resonance work?

Traps make use if magnetic field

13

Describe tandem MS/MS

Have multiple mass analysers
Allows selection and isolation of specific ions
Two mass analysers separated by a collision cell
Collision induces dissociation of parent molecule into a series of daughter fragments