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Mass Spectrometry II
Mass Spectrometry II
Ion trap
Magnetic Sector
FB
Magnetic Sector
Magnetic Sector
Time of Flight MSIn a quadrupole MS masses are separated based on their flight path
In a time-of-flight MS masses are separated based on their inertia
detectorIon-source+++++
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Field-free flight zone
Mass is determined by the time it takes the ion to move from source to detector
t = L (length) (velocity)
=2V
(m/z)√+ -
(acceleration voltage)
(mass-to-charge)
Acceleration zone
235.16 to 235.19 amu
281.13 to 281.15 amu
193.12 to 193.14 amu
179.10 to 179.12 amu
169.09 to 169.08 amu
301.14 to 301.16 amu
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
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
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
MS Application
Data fromLC-ESI-single quad MS
Parent [M+1]
MW: 290.32 g mol-1
Degradation products
Anything strange…
Total ion chromatogram
Single ion chromatogram
MS Application
Experiment• LC-ESI coupled to a single quadrupole MS to determine the unit mass of degradation products
• 2 degradation products• [M+H] 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)
MS Application
Data fromLC-ESI-Ion trap MS (MS2)LC mobile phase is H2O and CH3OH
291 (trimethoprim) trapped in ion trapAccelerated/dissociated and the products detected
[M+H] is 291
291 m/z → products
MS Application
MS Applications
• 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
Experiment• LC-ESI coupled to a single quadrupole MS to determine the unit mass of degradation products
• 2 degradation products• [M+H] 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
Data fromLC-ESI-Ion trap MS (MS2)
Degradation product 307 m/z trapped in ion trap Accelerated/dissociated and the products detected
D2O and CD3OD
307-18Loss of water[M + H – H2O]+
307 m/z → products
MS Application
Data fromLC-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
D2O and CD3OD
Can be formed from the dissociation of 307m/z or 289 m/z
307 m/z → 289 m/z → products
MS Application
Data fromLC-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
D2O and CD3OD
307 m/z → 274 m/z → products
Can be formed from the dissociation of
289 m/z and 274 m/z
MS Application
Products• Use MS3 data to propose a fragmentation pathway for 307 m/z degradation product• Structure confirmation
• 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
Experiment• LC-ESI coupled to a single quadrupole MS to determine the unit mass of degradation products
• 2 degradation products• [M+H] 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
MS Application
- H, - OH, - CH3
Data fromLC-ESI-Ion trap MS (MS2 and MS3)
Propose fragment structures
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
Answer• Degradation of trimethoprim is possible using nitrifying activated sludge• Degradation products identified using several MS techniques
MS Application
Data fromLC-ESI-Ion trap MSLC mobile phase is D2O and CD3OD
296 (d-trimethoprim) trapped in ion trapAccelerated/dissociated and the products detected
[M+D] is 296
MS Application
Data fromLC-ESI-Ion trap MS
D2O and CD3OD
H2O and CH3OH
MS Application
