2. MASS SPECTROMETRY
a powerful and versatile analytical tool for
obtaining information about the identity of an
unknown compound, its molecular mass, its
elemental composition, and in many cases, its
chemical structure.
3. 29A PRINCIPLES OF MASS
SPECTROMETRY
in the mass spectrometer, analyte molecules are
converted to ions by applying energy to them.
the ions formed are separated on the basis of their
mass-to-charge ratio (m/z)
and then directed to a transducer that converts the number
of ions (abundance) into an electrical signal.
the ions of different mass-to-charge ratios are directed to
the transducer sequentially by scanning or made to strike
a multichannel transducers simultaneously
4. 29A-1 ATOMIC MASSES
one unified atomic mass unit on this scale is equal to
1/12 the mass of neutral carbon atom.
atomic and molecular masses are usually expressed in
terms of the atomic mass scale, based on a specific
isotope of carbon.
the unified atomic mass is given the symbol (u).
one unified mass unit is commonly termed one
Dalton (Da).
5. 29A-2 MASS-TO-CHARGE RATIO (m/z) OF AN ION
is the quantity of most interest because the
mass spectrometer separates ions
according to this ratio.
6. 29B MASS SPECTROMETERS
is an instrument that produces ions, separates
them according to their m/z values, detects
them, and plots the mass spectrum. such
instruments vary widely in size, resolution,
flexibility, and cost.
8. Mass spectrometry MS video
https://www.youtube.com/watch?v=J-
wao0O0_qM&index=1&list=LLyKzvcAWJuLXMTUnqx31o4w
9. 29B-2 MASS ANALYZERS
COMMON MASS ANALYZERS FOR
MASS SPECTROMETRY
BASIC TYPE ANALYSIS PRINCIPLE
MAGNETIC SECTOR DEFLECTION OF IONS IN A MAGNETIC FIELD. ION TRAJECTORIES
DEPEND ON m/z value.
DOUBLE-FACING ELECTROSTATIC FOCUSING FOLLOWED BY MAGNETIC FIELD
DEFLECTION. TRAJECTORIES DEPEND ON m/z values.
QUADRUPOLE ION MOTION IN dc AND RADIO-FREQUENCY FIELDS. ONLY CERTAIN
m/z VALUES ARE PASSED
ION TRAP STORAGE OF IONS IN SPACE DEFINED BY RING AND EEND CAP
ELECTRODES. ELECTRIC FIELD SEQUENTIALLY EJECTS IONS OF
INCREASING m/z VALUES.
ION CYCLOTRON
RESONANCE
TRAPPING OF IONS IN CUBIC CELL UNDER INFLUENCE OF
TRAPPING VOLTAGE AND MAGNETIC FIELD. ORBITAL FREQUENCY
RELATED INVERELY TO m/z VALUES.
TIME-OF-FLIGHT EQUAL KINETIC ENERGY IONS ENTER DRIFT TUBE. DRIFT VELOCITY
AND THUS ARRIVAL TIME AT THE DETECTOR DEPEND ON MASS.
10. RESOLUTION OF MASS
SPECTROMETERS
the capability of mass spectrometer to differentiate between
masses is usually stated in terms of its resolution, r which is
defined as
R=m/▲m
Where ▲m is the mass difference between two adjacent
peaks that are just resolved and m is the nominal mass of
the first peak (the mean mass of the two peaks is sometimes
used instead).
11. SECTOR ANALYZERS
in the magnetic sector analyzer, separation is based on the
deflection of ions in the magnetic field.
12. QUADRUPOLE MASS ANALYZERS
the quadrople mass analyzer consist of four cylindrical rods, as
illustrated in figure 29-3. quadrople analyzers are mass filters that only
allow ions of a certain mass-to-charge ratio to pass.
13. Quadrupole mass analyzer video
https://www.youtube.com/watch?v=IowMQnI6Rxc
14. TIME-OF-FLIGHT MASS ANALYZERS
the time-of-flight (TOF) mass spectrometer represents another
approach to mass analysis. in a TOF analyzer, a packet of ions with
nearly identical kinetic energies is rapidly sampled, and the ions
enter a field-free region.
15. 29B-3 TRANSDUCERS FOR MASS
SPECTROMETRY
several types of ion transducers are available for mass
spectrometry. the most common transducer is the electron
multiplier.
continuous-dynode electron multipliers are also
popular.
in addition to electron multiplier transducers, faraday cup
transducers and array transducers have become
available for mass spectrometry.
16. 29C ATOMIC MASS SPECTROMETRY
atomic mass spectrometry has been around for
many years, ICPMS (Inductively Coupled Plasma-
Mass Spectrometry) is widely used technique for
the simultaneous determination of over 70
elements in few minutes.
18. 29C-1 SOURCES FOR-ATOMIC MASS
SPECTROMETRY
in MS applications, the ICP serves as both an atomizer and an
ionizer. Solution samples maybe introduce by a conventional or
an ultrasonic nebulizer.
extracting ions from the plasma can present a major technical
problem in ICPMS. while an ICP operates atmospheric pressure.
mass spectrometer operates at high vacuum, typically less than
𝟏𝟎−𝟔 torr. The interface region consist of two metal cones, called
the sampler and the skimmer. Each cone has small orifice, 1mm
19. COMMON IONIZATION SOURCES FOR
ATOMIC MASS SPECTROMETRY
Name Acronym Atomic Ion Sources Typical Mass Analyzer
Inductively coupled
plasma
ICPMS High temp argon
plasma
Quadrupole
Direct current plasma DCPMS High temp argon
plasma
Quadrupole
Microwave-induced
plasma
MIPMS High temp argon
plasma
Quadrupole
Spark source SSMS Radio-frequency
electric spark
Double-focusing
Glow discharge GDMS Glow-discharge
plasma
Double-focusing
20. OTHER IONIZATION SOURCES FOR
ATOMIC MASS SPECTROMETRY
of the sources listed in table 29-2, the spark source
and the glow discharge have received the most
attention. spark source atomic mass spectrometry
(SSMS) was first introduce in the 1930’s as a
general tool for multi-element isotope trace
analyses.
21. 29C-2 ATOMIC MASS SPECTRA AND
INTERFERENCES
because the ICP source predominates in atomic
mass spectrometry, we focus our discussion on
ICPMS. the simplicity of ICPMS spectra, lead early
workers in the field to have hopes of an
“interference-free method.”
interference effects in atomic mass spectroscopy fall
in to two broad categories: spectroscopic
interferences and matrix interferences.
22. SPECTROSCOPIC INTERFERENCE
Occurs when an ionic species in the plasma has the
same m/z value as an analyte ion. Most is from
polyatomic ions, doubly charge ions, refractory
oxide ions.
High resolution spectrometers can reduce or
eliminate these interference.
23. MATRIX INTERFERENCE
Occurs when concentrations of matrix species exceed about 500 to
1000 µg/mL.
It causes reduction in the analyte signal.
Such effects can be minimized by diluting the sample, altering the
intro procedure and separating the interfering species.
24. 29D MOLECULAR MASS
SPECTROMETRY
Currently, mass spectrometry is being applied to the
determination of the structure of polypeptides,
proteins, and other high-molecular-mass
biopolymers.
26. MOLECULAR MASS SPECTRA
Results are displayed as spectra of the relative abundance of
detected ions as a function of the mass-to-charge ratio. The
atoms or molecules in the sample can be identified by
correlating known masses to the identified masses or through
a characteristic fragmentation pattern.
A mass spectrum (plural spectra) is a plot of the ion signal as
a function of the mass-to-charge ratio.
27. 29D-2 ION SOURCES
BASIC TYPE NAME AND ACRONYM METHOD OF IONIZATION TYPE OF SPECTRA
GAS PHASE ELECTRON IMPACT (EI)
CHEMICAL IONIZATION (CI)
ENERGETIC ELECTRONS
REAGENT GASEOUS IONS
FRAGMENTATION PATTERNS
PROTON ADDUCTS, FEW
FRAGMENTS
DESORPTION FAST ATOM BOMBARDMENT (FAB)
MATRIX ASSISTED LASER
DESORPTION/IONIZATION (MALDI)
ELECTROSPRAY IONIZATION (ESI)
ENERGETIC ATOMIC BEAM
HIGH-ENERGY PHOTONS
ELECTRIC FIELD PRODUCES
CHARGED SPRAY WHICH
DESOLVATES
MOLECULAR IONS & FRAGMENTS
MOLECULAR IONS, MULTIPLY
CHARGED IONS
MULTIPLY CHARGED MOLECULAR
IONS
COMMON ION SOURCES FOR MOLECULAR MASS SPECTROMETRY
28. 29D-3 MOLECULAR MASS
SPECTROMETRIC INSTRUMENTATION
Molecular mass spectrometric instrumentation is similar with
atomic mass spectrometry.
29. MASS ANALYZERS
the quadrupole mass analyzer is commonly used
with GC/MS systems.
tandem mass spectrometry, also called mass
spectrometry-mass spectrometry (MS/MS) mented
ion to be obtained.
30. COMMON MASS ANALYZERS
FOR MASS SPECTROMETRY
BASIC TYPE ANALYSIS PRINCIPLE
MAGNETIC SECTOR DEFLECTION OF IONS IN A MAGNETIC FIELD. ION TRAJECTORIES DEPEND ON
m/z value.
DOUBLE-FACING ELECTROSTATIC FOCUSING FOLLOWED BY MAGNETIC FIELD DEFLECTION.
TRAJECTORIES DEPEND ON m/z values.
QUADRUPOLE ION MOTION IN dc AND RADIO-FREQUENCY FIELDS. ONLY CERTAIN m/z VALUES
ARE PASSED
ION TRAP STORAGE OF IONS IN SPACE DEFINED BY RING AND EEND CAP ELECTRODES.
ELECTRIC FIELD SEQUENTIALLY EJECTS IONS OF INCREASING m/z VALUES.
ION CYCLOTRON
RESONANCE
TRAPPING OF IONS IN CUBIC CELL UNDER INFLUENCE OF TRAPPING VOLTAGE
AND MAGNETIC FIELD. ORBITAL FREQUENCY RELATED INVERELY TO m/z
VALUES.
TIME-OF-FLIGHT EQUAL KINETIC ENERGY IONS ENTER DRIFT TUBE. DRIFT VELOCITY AND THUS
ARRIVAL TIME AT THE DETECTOR DEPEND ON MASS.
MASS ANALYZERS THAT ARE
USED IN MOLECULAR MASS
SPECTROMETRY
31. APPLICATIONS OF MASS
SPECTROMETRY
Mass spectrometry has both qualitative and quantitative uses.
These include identifying unknown compounds, determining the
isotopic composition of elements in a molecule, and determining the
structure of a compound by observing its fragmentation.
MS is now in very common use in analytical laboratories that study
physical, chemical, or biological properties of a great variety of
compounds.
32. APPLICATIONS
Determination of Morphine and Codeine in Human Urine by Gas Chromatography-Mass
Spectrometry
Xiaoqian Zhang, Mengchun Chen, Gaozhong Cao, and Guoxin Hu
School of Pharmacy of Wenzhou Medical University, Wenzhou 325035, China
The First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
Received 30 May 2013; Revised 22 August 2013; Accepted 28 August 2013
Academic Editor: Jianxiu Du
33. APPLICATIONS
Advances in structure elucidation of small molecules using
mass spectrometry
Tobias Kind and Oliver Fiehn
Genome Center–Metabolomics, University of California Davis,
Davis, CA 95616 USA
34. APPLICATIONS
Simultaneous Quantification of Methadone, Cocaine, Opiates, and
Metabolites in Human Placenta by Liquid Chromatography–Mass
Spectrometry
Ana de Castro, Marta Concheiro, Diaa M. Shakleya,and Marilyn A. Huestis,
Chemistry and Drug Metabolism, Intramural Research Program, National
Institute on Drug Abuse, NIH, Baltimore, Maryland 21224
Forensic Toxicology Service, Institute of Legal Medicine, University of
Santiago de Compostela, San Francisco s/n, Santiago de Compostela,
15782 Spain
35. APPLICATIONS
11-Nor-9-carboxy-Δ9-tetrahydrocannabinol quantification in human
oral fluid by liquid chromatography–tandem mass spectrometry
Karl B. Scheidweiler, Sarah K. Himes, Xiaohong Chen, Hua-Fen Liu, and
Marilyn A. Huestis
Karl B. Scheidweiler, Chemistry and Drug Metabolism, Intramural
Research Program, National Institute on Drug Abuse, National Institutes of
Health, Biomedical Research Center, 251 Bayview Boulevard Suite 200
Room 05A-721, Baltimore, MD 21224, USA;
