Mass SpectrometryMass Spectrometry

Inlet Inlet systemsystem

Ion Ion SourceSource

Mass Mass AnalyzeAnalyze

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Ion Ion DetectoDetecto

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Mass AnalyzersMass Analyzers

Which one is best for a given Which one is best for a given application?application?

Depends on resolution (separating power Depends on resolution (separating power of mass spectrometer)of mass spectrometer)

For two peaks m and m+For two peaks m and m+m m resolution is: m/resolution is: m/mm

MW of CMW of C1616HH2222OO22 and C and C1717HH2626O ?O ?

Resolution required? Resolution required?

Types of Mass Types of Mass AnalyzersAnalyzers

Magnetic Sector: Single Focusing:Magnetic Sector: Single Focusing: A magnetic field A magnetic field is used to focus ions based on their momentum as is used to focus ions based on their momentum as they are ejected from an ion source at high energy. they are ejected from an ion source at high energy. Resolution <2000Resolution <2000

Focuses based on momentum

Magnetic sector double focusing:Magnetic sector double focusing: An An electrostatic analyzer is used serially with electrostatic analyzer is used serially with a magnet to select monoenergetic ions. a magnet to select monoenergetic ions. High resolution >10,000 mass up to High resolution >10,000 mass up to 100,000Da100,000Da

Quadrupole:Quadrupole: electronic mass filter that electronic mass filter that selects ions of a single m/z by selects ions of a single m/z by superimposing a radio frequency and a superimposing a radio frequency and a direct current potentialdirect current potential

Unit mass resolution mass range to approximately 2000 most common detector coupled to GC systems

Time of Flight Time of Flight Measures all m/z Measures all m/z simultaneouslysimultaneously

Ion TrapIon Trap

RF fields yield m/zband of stability

• 3D RF Fields• Detect those ions that are selectively ejected due to

destabilized trajectory

Quadrupole

FT-ICR (Fourier FT-ICR (Fourier Transform Ion Cyclotron Transform Ion Cyclotron Resonance)Resonance)

Advantages of FT:Advantages of FT:1.1. Improved S/NImproved S/N

2.2. Greater speed per spectrumGreater speed per spectrum

3.3. Higher sensitivityHigher sensitivity

4.4. Greater resolutionGreater resolution

FT-ICRFT-ICR

FT-ICRFT-ICR

Animation: Animation: http://info.med.yale.edu/wmkeck/http://info.med.yale.edu/wmkeck/prochem/fticr/FTICR.mpgprochem/fticr/FTICR.mpg

Mass SpectrometryMass Spectrometry

Inlet Inlet systemsystem

Ion Ion SourceSource

Mass Mass AnalyzeAnalyze

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Ion Ion DetectoDetecto

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Inlet SystemsInlet Systems

Purpose is to Purpose is to introduce a very introduce a very small amount of small amount of sample into the sample into the mass mass spectrometer so spectrometer so that its that its components may components may be converted into be converted into gas ionsgas ions Want minimal loss of vacuum

Direct Probe InletDirect Probe Inlet

Good for solid and Good for solid and non-volatile liquidsnon-volatile liquids

Sample is on Sample is on surface, probe surface, probe positioned near positioned near ionization source ionization source and slit leading to and slit leading to spectrometerspectrometer

Good for low Good for low concentrations or concentrations or thermally unstable thermally unstable compoundscompounds

Mass SpectrometryMass Spectrometry

Inlet Inlet systemsystem

Ion Ion SourceSource

Mass Mass AnalyzeAnalyze

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Ion Ion DetectoDetecto

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Detectors for MSDetectors for MS

Need to be very Need to be very sensitivesensitive

Typical gains are Typical gains are 10^5 up to 10^5 up to 10^8!10^8!

Provides high Provides high current with current with nanosecond nanosecond response timeresponse time Continuous Dynode

Mass Spectrometry Mass Spectrometry SummarySummary

1.1. MS is the ultimate in a qualitative MS is the ultimate in a qualitative analysis tool!analysis tool!

2.2. MS by itself is most useful for MS by itself is most useful for analyzing pure compoundsanalyzing pure compounds

3.3. Analyte in mixture requires MS to Analyte in mixture requires MS to be hyphenated to another be hyphenated to another techniquetechnique

For ex. GC-MS, LC-MS, MS-MS, or CE-MSFor ex. GC-MS, LC-MS, MS-MS, or CE-MS

Advantages of MS Advantages of MS

1.1. Detection limits up to 3 orders of Detection limits up to 3 orders of magnitude better than optical magnitude better than optical methodsmethods

2.2. Remarkably simple spectra that Remarkably simple spectra that are usually unique and easily are usually unique and easily interpretableinterpretable

Disadvantages of MSDisadvantages of MS

1.1. Instrument costs 2-3x higher Instrument costs 2-3x higher than optical atomic instrumentsthan optical atomic instruments

2.2. Instrument drift can be as high Instrument drift can be as high as 5-10% per hour as 5-10% per hour

3.3. Subject to interferencesSubject to interferences

TONS of applications!TONS of applications!

Regiospecific Analysis of Regiospecific Analysis of Diricinoleoylacylglycerols in Castor (Diricinoleoylacylglycerols in Castor (Ricinus Ricinus communiscommunis L.) Oil by Electrospray Ionization- L.) Oil by Electrospray Ionization-Mass SpectrometryMass Spectrometry

Characterization of Puff-by-Puff Resolved Characterization of Puff-by-Puff Resolved Cigarette Mainstream Smoke by Single Photon Cigarette Mainstream Smoke by Single Photon Ionization-Time-of-Flight Mass Spectrometry Ionization-Time-of-Flight Mass Spectrometry and Principal Component Analysisand Principal Component Analysis

Electrospray Ionization Mass Spectrometry Electrospray Ionization Mass Spectrometry Fingerprinting of Brazilian Artisan Cachaça Aged Fingerprinting of Brazilian Artisan Cachaça Aged in Different Wood Casksin Different Wood Casks

Determination of Nitrofuran Residues in Milk of Determination of Nitrofuran Residues in Milk of Dairy Cows Using Liquid Chromatography-Dairy Cows Using Liquid Chromatography-Tandem Mass SpectrometryTandem Mass Spectrometry