Mass Spectrometry II

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• Mass Spectrometry II

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Ion trap
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Magnetic Sector
FB
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Magnetic Sector
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Magnetic Sector
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Time of Flight MS
In a quadrupole MS masses are separated based on
their flight path
In a time-of-flight MS masses are separated based
on their inertia
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301.14 to 301.16 amu
169.09 to 169.08 amu
179.10 to 179.12 amu
193.12 to 193.14 amu
281.13 to 281.15 amu
235.16 to 235.19 amu
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MS Application
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MS Application

• Environmental Issue
• Presence of bioloigcally-active compounds
  (pharmaceuticals) that are not degraded in a
  wastewater treatment plant
• Compound of interest is trimethoprim, an
  anti-microbial used to treat infectious diseases
  in humans

• Analytical - want to analyze for trimethoprim
• LC/GC?

• Ionization source?

LC why?
ESI why?

• Hypothesis
• Primary treatment of wastewater with nitrifying
  activated sludge will degrade trimethoprim

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MS Application

• Hypothesis
• Primary treatment of wastewater with nitrifying
  activated sludge will degrade trimethoprim

• Experiment
• Small scale laboratory batch reactor was used to
  degrade trimethoprim
• LC-ESI coupled to a single quadrupole MS to
  determine the unit mass of degradation products
• LC-ESI coupled to an ion trap MS to determine
  structural features of the degradation products
• LC-ESI coupled to a quadrupole time of flight MS
  to determine the accurate mass of the degradation
  products to get a chemical formula

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MS Application

• Hypothesis
• Primary treatment of wastewater with nitrifying
  activated sludge will degrade trimethoprim

• Experiment
• Small scale laboratory batch reactor was used to
  degrade trimethoprim
• LC-ESI coupled to a single quadrupole MS to
  determine the unit mass of degradation products
• LC-ESI coupled to an ion trap MS to determine
  structural features of the degradation products
• LC-ESI coupled to a quadrupole time of flight MS
  to determine the accurate mass of the degradation
  products to get a chemical formula

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MS Application
Data from LC-ESI-single quad MS
MW 290.32 g mol-1
Total ion chromatogram
Degradation products
Parent M1
Single ion chromatogram
Anything strange
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MS Application

• Experiment
• LC-ESI coupled to a single quadrupole MS to
  determine the unit mass of degradation products
• 2 degradation products
• MH of 307 m/z and 325 m/z
• Increased mass but earlier LC elution
• Suggests oxidation
• Mass difference between 291 m/z and 307 m/z is
  16 m/z (oxygen)
• Mass difference between 291 m/z and 325 m/z is
  34 m/z (2O and 2 H)

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MS Application
Data from LC-ESI-Ion trap MS (MS2) LC mobile
phase is H2O and CH3OH
291 (trimethoprim) trapped in ion
trap Accelerated/dissociated and the products
detected
MH is 291
291 m/z ? products
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MS Applications

• Experiment
• LC-ESI coupled to a single quadrupole MS to
  determine the unit mass of degradation products
• 2 degradation products
• MH of 307 m/z and 325 m/z
• Increased mass but earlier LC elution
• Suggests oxidation
• Mass difference between 291 m/z and 307 m/z is
  16 m/z (oxygen)
• Mass difference between 291 m/z and 325 m/z is
  34 m/z

• LC-ESI coupled to an ion trap MS to determine
  structural features of the degradation products
• Parent
• Demonstrates that the phenyl rings are
  recalcitrant to dissociation
• Useful information for the ion trap analysis of
  the degradation products

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MS Application
Data from LC-ESI-Ion trap MS (MS2)
307-18 Loss of water M H H2O
Degradation product 307 m/z trapped in ion trap
Accelerated/dissociated and the products detected
307 m/z ? products
D2O and CD3OD
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MS Application
Data from LC-ESI-Ion trap MS (MS3)
Degradation product 307 m/z trapped in ion trap
Accelerated/dissociated and 289 m/z trapped in
ion trap Accelerated/dissociated and the
products detected
Can be formed from the dissociation of 307m/z or
289 m/z
307 m/z ? 289 m/z ? products
D2O and CD3OD
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MS Application
Data from LC-ESI-Ion trap MS (MS3)
Degradation product 307 m/z trapped in ion trap
Accelerated/dissociated and 274 m/z trapped in
ion trap Accelerated/dissociated and the
products detected
Can be formed from the dissociation of 289 m/z
and 274 m/z
307 m/z ? 274 m/z ? products
D2O and CD3OD
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MS Application

• Experiment
• LC-ESI coupled to a single quadrupole MS to
  determine the unit mass of degradation products
• 2 degradation products
• MH of 307 m/z and 325 m/z
• Increased mass but earlier LC elution
• Suggests oxidation
• Mass difference between 291 m/z and 307 m/z is
  16 m/z (oxygen)
• Mass difference between 291 m/z and 325 m/z is
  34 m/z

• LC-ESI coupled to an ion trap MS to determine
  structural features of the degradation products
• Parent
• Demonstrates that the phenyl rings are
  recalcitrant to dissociation
• Useful information for the ion trap analysis of
  the degradation products

• Products
• Use MS3 data to propose a fragmentation pathway
  for 307 m/z degradation product
• Structure confirmation

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MS Application
Data from LC-ESI-Ion trap MS (MS2 and MS3)
Propose fragment structures
- H, - OH, - CH3
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MS Application

• Experiment
• Small scale laboratory batch reactor was used to
  degrade trimethoprim
• LC-ESI coupled to a single quadrupole MS to
  determine the unit mass of degradation products
• LC-ESI coupled to an ion trap MS to determine
  structural features of the degradation products
• LC-ESI coupled to a quadrupole time of flight MS
  to determine the accurate mass of the degradation
  products to get a chemical formula

• Hypothesis
• Primary treatment of wastewater with nitrifying
  activated sludge will degrade trimethoprim

• Answer
• Degradation of trimethoprim is possible using
  nitrifying activated sludge
• Degradation products identified using several MS
  techniques

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MS Application
Data from LC-ESI-Ion trap MS LC mobile phase is
D2O and CD3OD
296 (d-trimethoprim) trapped in ion
trap Accelerated/dissociated and the products
detected
MD is 296
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MS Application
Data from LC-ESI-Ion trap MS
H2O and CH3OH
D2O and CD3OD