Mass Spectrometry Flashcards
instrument that produces ions, separates them according to their m/z values, detects them, and plots the mass spectrum
mass spectrometer
initial step in the mass spectrometric study of molecules
produce gas phase ions of substance
how is the process of producing gas phase ions of a substance done
through electron ionization
occurs in each primary product ion that is produced from the molecular ion
fragmentation
how are ions detected in the mass spectr0meter
proportion to their abundance after being separated based on their mass-to-charge ratio
what is the outcome of ions detected in proporiton to their abundance after being separated based on their mass-to-charge ration
creation of molecule’s mass spectrum
what happens to the analyte in the mass spectrometer
converted to ions by applying energy
how are ions separated in mass spectrometer
on basis of their mass-to-charge ratio (m/z)
converts the number of ions into an electric signal
transducer
ion abundace plotted against mass-to-charge ratio
mass spectrum
General Components and Analytical Steps of Mass Spectrometry
- inlet system
- ion source
- mass analyzer
- ion transducer (detector)
where samples are introduced to the mass spectrometer
inlet system
- where components of the sample are converted into gaseous ions
- conversion is achieved through bombardment with electrns, photons, ions, or molecules
ion source
how is the ionization accomplished
thermal or electrical energy
- separates ions based on their mass-to-charge raions
- designed to have high resolution and ion transmitting rates
mass analyzer
- 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
ion transducer (detector)
Common Mass Analyzers for Mass Spectrometry
- magnetic sector
- double-focusing
- quadruple
- ion trap
- ion cyclotron resonance
- time-of-flight
- deflection of ions in a magnetic flied
- ion trajectories depend on m/z value
magnetic sector
- electrostatic focusing followed by magnetic field detection
- trajectories depend on m/z values
double-focusing
- ion motion in dc and radio-frequency fields
- only certain m/z values are passed
quadruple
- storage of ions in space defined by ring and end cap electrodes
- electric field sequentially ejects ions of increasing m/z values
ion trap
- trapping of ions in cubic cell under influence of trapping voltage and magnetic field
- orbital frequency related inversely to m/z value
ion cyclotton resonance
- equal kinetic energy ions enter drift tube
- drift veolcity and thus arrival time at detector depend on mass
time-of-flight
application of mass spectrometry example
measure 15N-nitrate in isotope-enrichment experiments
