CHAPTER 29:

MASS SPECTROMETRY

GROUP 6: BMLS-1E

• ONDONG, Aaron Luis

• OTACAN, Ma. Lunie Fe Bianca

• OCAMPO, Ma. Christine

• CHAN, Joy Anne

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.

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

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).

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.

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.

29B-1 COMPONENTS OF MASS SPECTROMETER

Mass spectrometry MS video

https://www.youtube.com/watch?v=J-

wao0O0_qM&index=1&list=LLyKzvcAWJuLXMTUnqx31o4w

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.

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).

SECTOR ANALYZERS

in the magnetic sector analyzer, separation is based on the

deflection of ions in the magnetic field.

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.

Quadrupole mass analyzer video

https://www.youtube.com/watch?v=IowMQnI6Rxc

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.

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.

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.

ICP-MS video

https://www.youtube.com/watch?v=L-FYh2z9mi0

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

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

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.

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.

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.

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.

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.

29D-1 MOLECULAR MASS SPECTRA

MASS SPECTRUM OF ETHYL BENZENE

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.

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

29D-3 MOLECULAR MASS

SPECTROMETRIC INSTRUMENTATION

Molecular mass spectrometric instrumentation is similar with

atomic mass spectrometry.

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.

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

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.

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

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

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

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;