Mass Spectrometry

Question 1

instrument that produces ions, separates them according to their m/z values, detects them, and plots the mass spectrum

Answer 1

mass spectrometer

Question 2

initial step in the mass spectrometric study of molecules

Answer 2

produce gas phase ions of substance

Question 3

how is the process of producing gas phase ions of a substance done

Answer 3

through electron ionization

Question 4

occurs in each primary product ion that is produced from the molecular ion

Answer 4

fragmentation

Question 5

how are ions detected in the mass spectr0meter

Answer 5

proportion to their abundance after being separated based on their mass-to-charge ratio

Question 6

what is the outcome of ions detected in proporiton to their abundance after being separated based on their mass-to-charge ration

Answer 6

creation of molecule’s mass spectrum

Question 7

what happens to the analyte in the mass spectrometer

Answer 7

converted to ions by applying energy

Question 8

how are ions separated in mass spectrometer

Answer 8

on basis of their mass-to-charge ratio (m/z)

Question 9

converts the number of ions into an electric signal

Answer 9

transducer

Question 10

ion abundace plotted against mass-to-charge ratio

Answer 10

mass spectrum

Question 11

General Components and Analytical Steps of Mass Spectrometry

Answer 11

1. inlet system
2. ion source
3. mass analyzer
4. ion transducer (detector)

Question 12

where samples are introduced to the mass spectrometer

Answer 12

inlet system

Question 13

• where components of the sample are converted into gaseous ions
• conversion is achieved through bombardment with electrns, photons, ions, or molecules

Answer 13

ion source

Question 14

how is the ionization accomplished

Answer 14

thermal or electrical energy

Question 15

• separates ions based on their mass-to-charge raions
• designed to have high resolution and ion transmitting rates

Answer 15

mass analyzer

Question 16

• converts ions of particular m/z values into an electric signal
• signal is then processed by the data handlins system to generate the mass spectrum

Answer 16

ion transducer (detector)

Question 17

Common Mass Analyzers for Mass Spectrometry

Answer 17

1. magnetic sector
2. double-focusing
3. quadruple
4. ion trap
5. ion cyclotron resonance
6. time-of-flight

Question 18

• deflection of ions in a magnetic flied
• ion trajectories depend on m/z value

Answer 18

magnetic sector

Question 19

• electrostatic focusing followed by magnetic field detection
• trajectories depend on m/z values

Answer 19

double-focusing

Question 20

• ion motion in dc and radio-frequency fields
• only certain m/z values are passed

Answer 20

quadruple

Question 21

• storage of ions in space defined by ring and end cap electrodes
• electric field sequentially ejects ions of increasing m/z values

Answer 21

ion trap

Question 22

• trapping of ions in cubic cell under influence of trapping voltage and magnetic field
• orbital frequency related inversely to m/z value

Answer 22

ion cyclotton resonance

Question 23

• equal kinetic energy ions enter drift tube
• drift veolcity and thus arrival time at detector depend on mass

Answer 23

time-of-flight

Question 24

application of mass spectrometry example

Answer 24

measure 15N-nitrate in isotope-enrichment experiments