COVER PAGE
TERM PAPER REPORT ON
MASS SPECTROMETRY
BY
GROUP 1
300L
DEPARTMENT OF CHEMICAL ENGINEERING
FACULTY OF ENGINEERING
21ST FEBRUARY, 2024
TABLE OF CONTENTS
COVER PAGE ......................................................................................................................... 1
TABLE OF CONTENTS ........................................................................................................ 2
LIST OF GROUP MEMBERS .............................................................................................. 3
ABSTRACT............................................................................................................................. 4
INTRODUCTION TO MASS SPECTROMETRY ................................................................. 5
PRINCIPLES OF MASS SPECTROMETRY ...................................................................... 6
MASS ANALYZERS ..............................................................................................................7
ION DETECTION METHOD ................................................................................................. 8
APPLICATIONS OF MASS SPECTROMETRY IN CHEMICAL ENGINEERING ......... 9
CHALLENGES AND LIMITATIONS .................................................................................. 11
CONCLUSION ...................................................................................................................... 13
REFERENCES ..................................................................................................................... 14
LIST OF GROUP MEMBERS
S/N
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NAMES
OKECHUKWU PROSPER CHINEMERE
OGIEVA OSARUMWENSE SAMSON
JOHN EMMANUEL KELECHI
OSIDE NNAMAKA CHARLES
IZEKOR MICHAEL
EDWIN ACHEMA
ADAMU SULAIMAN
ADELAKUN ANUOLUWAPO HEZEKIAH
AGHE PROMISE OGHENETEGA
AIGBE -OMORUYI MARVELLOUS EFOSA
AIKPITANYI AIMUAMWOSA LARY
AJIDUAH MIRACLE IJEOMA
AKERELE AUGUSTINA AVOVOME
AKHADE DANIEL EWEAI
AMADASUN AISOSA
ANESI PRECIOUS EMIKE
ARHEWOH PRAISE OSOSE
ASANI DAVID DAMILOLA
ASIKA EMMANUEL BRIGHT
AWHOTUGBE SOLOMON
AYINBUOMWAN OSARIEMEN HILDA
CHIBUIKE CHUKWUEMEKA EMMANUEL
MAT. NUMBER
ENG1707231
ENG1808684
ENG1905010
ENG1905042
ENG195008
ENG2001999
ENG2002000
ENG2002001
ENG2002002
ENG2002003
ENG2002004
ENG2002005
ENG2002007
ENG2002008
ENG2002010
ENG2002012
ENG2002013
ENG2002014
ENG2002015
ENG2002016
ENG2002017
ENG2002018
SAT.
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ABSTRACT
Mass spectrometry (MS) is a vital analytical technique widely employed in
chemical engineering for analyzing and characterizing chemical compounds
in various processes and systems. This paper provides an overview of the
principles, applications, and challenges associated with mass spectrometry
in chemical engineering. It explores the fundamentals of mass spectrometry,
including ionization, mass analysis, and detection methods, and discusses its
applications in process monitoring, catalyst characterization, environmental
monitoring, materials analysis, and safety management.
However, despite its significance, mass spectrometry encounters challenges
such as sample preparation complexities, matrix effects, instrument
operation intricacies, data interpretation hurdles, sensitivity limitations,
instrumentation costs, and data processing constraints. Addressing these
challenges requires concerted efforts in method development,
instrumentation improvement, and training initiatives to harness the full
potential of mass spectrometry in advancing research, innovation, and
sustainability in chemical engineering.
INTRODUCTION TO MASS SPECTROMETRY
Mass (symbolized m) is a dimensionless quantity representing the amount of
matter in a particle or object. The standard unit of mass in the International
System (SI) is the kilogram (kg). On the other hand, a spectrometer is any
instrument that is used to measure the variation of a physical characteristic
over a given range; i.e. a spectrum. This could be a mass-to-charge ratio
spectrum in the case of a mass spectrometer, the variation of nuclear
resonant frequencies in an NMR spectrometer or the change in the absorption
and emission of light with wavelength in an optical spectrometer. Hence,
Spectrometry is the measurement of the interactions between light and
matter, and the reactions and measurements of radiation intensity and
wavelength. In other words, spectrometry is a method of studying and
measuring a specific spectrum, and it's widely used for the spectroscopic
analysis of sample materials.
Therefore, Mass spectrometry, is an analytic technique by which chemical
substances are identified by the sorting of gaseous ions in electric and
magnetic fields according to their mass-to-charge ratios. The instruments
used in such studies are called mass spectrometers and mass spectrographs,
and they operate on the principle that moving ions may be deflected by electric
and magnetic fields. The two instruments differ only in the way in which the
sorted charged particles are detected. In the mass spectrometer they are
detected electrically, in the mass spectrograph by photographic or other
nonelectrical means; the term mass spectroscope is used to include both
kinds of devices. Since electrical detectors are now most commonly used, the
field is typically referred to as mass spectrometry.
Mass spectrometry (MS) is a sensitive and powerful analytical technique, in
which ionized sample molecules are separated according to their mass to
charge ratios (m/z) by the application of electric and/or magnetic fields. If the
ionization regime deposits sufficient excess energy, a proportion of the
sample molecules will dissociate, the pattern of product ions formed being
dependent on the structure of the intact compound (Fig. 1). A mass spectrum
thus consists of the masses (strictly mass to charge ratios, m/z) of these ions
plotted against abundance. Interpretation of the spectrum thus affords
information about both the mol wt and the structure of the sample. By the
standards of most other physical methods, mass spectrometry is fairly
sensitive, requiring somewhere between low picomoles and nanomoles of
material, depending on the ionization method employed, but against this must
be set its destructive nature.
PRINCIPLES OF MASS SPECTROMETRY
In chemical engineering, mass spectrometry relies on several key principles
to analyze and characterize chemical compounds effectively. Here are the
primary principles of mass spectrometry as related to chemical engineering:
1.
Ionization: The first principle involves ionizing molecules from a sample.
Various ionization techniques such as electron impact, chemical
ionization, and electrospray ionization are employed to generate ions
from the molecules present in the sample. This process converts neutral
molecules into charged ions, making them suitable for analysis in the
mass spectrometer.
2.
Mass-to-Charge Ratio (m/z): Mass spectrometry sorts ions based on
their mass-to-charge ratio (m/z). This ratio is the ratio of an ion's mass
to its charge, typically expressed in atomic mass units per elementary
charge (u/e). By measuring the m/z ratio, mass spectrometers can
distinguish between ions of different masses, allowing for the
identification and quantification of compounds present in the sample.
3.
Mass Analysis: Mass analyzers separate ions based on their m/z ratios.
Different types of mass analyzers, such as quadrupole, time-of-flight
(TOF), ion trap, and magnetic sector analyzers, employ distinct principles
to achieve this separation. For example, quadrupole analyzers use
radiofrequency voltages to selectively transmit ions of a specific m/z
ratio, while TOF analyzers separate ions based on their flight times
through a vacuum tube.
4.
Detection: Once ions are separated by the mass analyzer, they are
detected by a detector. The detector records the abundance of ions at each
m/z ratio, generating a mass spectrum. The intensity of the peaks in the
mass spectrum corresponds to the abundance of ions with specific m/z
ratios, providing valuable information about the composition of the
sample.
5.
Data Analysis: The final principle involves data analysis, where the mass
spectrum obtained from the detector is interpreted to identify the
compounds present in the sample and determine their concentrations.
This process often involves comparing experimental mass spectra to
reference spectra or databases of known compounds. Additionally,
advanced computational techniques and software algorithms are used to
analyze complex mass spectra and extract meaningful information about
the sample composition.
Figure 1: Mass Spectrometer
By leveraging these principles, chemical engineers utilize mass spectrometry
to characterize reaction products, monitor process streams, identify
impurities, assess product quality, and optimize process conditions in various
chemical
engineering
applications,
including
pharmaceuticals,
petrochemicals, environmental monitoring, and materials synthesis.
MASS ANALYZERS
Mass analyzers are crucial components of mass spectrometry instruments
that separate ions based on their mass-to-charge ratio (m/z). These
analyzers play a pivotal role in characterizing chemical compounds,
monitoring reactions, and analyzing process streams. Here are some
common types of mass analyzers and their concepts explained in the context
of chemical engineering:
1. Quadrupole Analyzer: The quadrupole analyzer consists of four parallel
metal rods arranged in a square or hyperbolic configuration. Radiofrequency
(RF) and direct current (DC) voltages are applied to the rods, creating a
varying electric field within the quadrupole.
When ions enter the quadrupole, they experience a combination of electric
fields that cause them to follow stable trajectories through the device. By
adjusting the RF and DC voltages, only ions with specific m/z ratios are
transmitted through the quadrupole and detected, while others are filtered
out.
Quadrupole analyzers are commonly used in chemical engineering for realtime monitoring of reaction products, quantification of reaction intermediates,
and analysis of process streams in industries such as pharmaceuticals,
petrochemicals, and environmental monitoring.
2. Time-of-Flight (TOF) Analyzer: In a TOF analyzer, ions are accelerated to a
constant kinetic energy and then injected into a flight tube. The ions travel
through the flight tube and reach a detector at different times based on their
m/z ratios.
Lighter ions travel faster through the flight tube and reach the detector earlier,
while heavier ions take longer to reach the detector. The time it takes for ions
to travel from the ion source to the detector is used to calculate their m/z
ratios.
TOF analyzers are employed in chemical engineering for high-resolution mass
analysis, accurate determination of molecular weights, and investigation of
complex mixtures in processes such as polymer synthesis, catalyst
characterization, and metabolomics.
3. Ion Trap Analyzer: Ion trap analyzers use electric and magnetic fields to
confine ions within a three-dimensional space. They consist of electrodes that
create a trapping region where ions can be stored temporarily.
Ions are injected into the ion trap and trapped by applying appropriate voltages
to the electrodes. By varying the voltages, ions can be selectively ejected from
the trap based on their m/z ratios for detection and analysis.
Ion trap analyzers find applications in chemical engineering for tandem mass
spectrometry experiments, structural elucidation of organic compounds, and
selective ion isolation for detailed analysis of reaction products and
impurities.
These mass analyzers, along with others such as magnetic sector analyzers
and Fourier transform ion cyclotron resonance (FT-ICR) analyzers, provide
chemical engineers with versatile tools for characterizing chemical
compounds, monitoring chemical processes, and advancing research and
development in various industries.
ION DETECTION METHOD
Some various ion detection methods used in mass spectrometry, including
electron multipliers, photomultiplier tubes, and microchannel plates:
1. Electron Multipliers: Electron multipliers consist of a series of dynodes
(metallic surfaces) coated with a material that emits electrons when struck
by ions. When an ion strikes the first dynode, it releases several electrons.
These electrons are then accelerated towards the next dynode, where they
generate more electrons through secondary emission. This process
repeats through multiple dynodes, resulting in a cascade of electron
amplification.
Electron multipliers offer high sensitivity due to their ability to amplify
electron signals exponentially. They can detect low levels of ions with high
efficiency, making them suitable for trace analysis and high-resolution
mass spectrometry.
2. Photomultiplier Tubes (PMTs): Photomultiplier tubes convert light signals
generated by ion interactions into electrical signals. When an ion strikes a
phosphor-coated surface within the PMT, it emits photons. These photons
are then absorbed by a photocathode, releasing photoelectrons. The
photoelectrons are accelerated towards a series of dynodes, where they
undergo multiplication through secondary emission, similar to electron
multipliers.
PMTs offer high sensitivity for detecting ion-induced light signals. They are
commonly used in techniques such as time-of-flight mass spectrometry
and fluorescence spectroscopy, where high sensitivity is essential for
detecting low-intensity signals.
3. Microchannel Plates (MCPs): Microchannel plates are thin, glass-like
plates with thousands of tiny channels (microchannels) running through
them. When ions strike the surface of an MCP, they release secondary
electrons. These electrons are then accelerated through the
microchannels by an applied voltage, causing them to undergo
amplification through collision-induced secondary emission as they travel
through the channels.
MCPs offer excellent sensitivity and spatial resolution, making them ideal
for detecting ions in time-of-flight mass spectrometers and imaging mass
spectrometry applications. They can detect individual ion events with high
efficiency and provide fast response times.
1.
2.
3.
4.
ADVANTAGES OF MASS SPECTROMETRY
It utilizes a small sample size.
It is faster.
It is capable of differentiating isotopes.
It is extremely sensitive ( parts per million)
5.
1.
2.
3.
4.
5.
It is the perfect tool to identify the presence or absence of a substance in
a given sample.
DISADVANTAGES OF MASS SPECTROMETRY
Mass spectrometry does not offer direct structural information and
cannot distinguish between optical and geometric isomers.
It requires pure samples.
Mass spectrometry is not suitable for non-volatile compounds and cannot
be used to identify hydrocarbons.
Frequent recalibration is needed, especially in quadrupole mass
spectrometers, due to the strong dependence of sensitivity and mass
discrimination factor on the stability of supply voltages.
Mass spectrometry may not be suitable for emergency situations due to
the lack of 24/7 availability, labor-intensive sample preparation, and slow
turn-around time of the analysis.
APPLICATIONS OF MASS SPECTROMETRY IN CHEMICAL
ENGINEERING
Certainly! Mass spectrometry finds various applications in chemical
engineering, contributing to process optimization, product quality control, and
materials analysis. Here are some key applications of mass spectrometry in
chemical engineering:
1. Process Monitoring and Control: Mass spectrometry is used for real-time
monitoring of chemical reactions and process streams in industries such as
petrochemicals, pharmaceuticals, and fine chemicals. It enables continuous
analysis of reaction intermediates, by-products, and impurities, facilitating
process optimization and ensuring product consistency and purity. Example:
In the petrochemical industry, mass spectrometry is employed to monitor
catalytic cracking and reforming processes, analyze gas composition in
refinery operations, and detect contaminants in hydrocarbon streams.
2. Catalyst Characterization: Mass spectrometry is utilized to characterize
catalysts used in various chemical processes, such as heterogeneous
catalysis, polymerization, and fuel cells. It provides insights into catalyst
composition, surface properties, and reaction mechanisms, aiding in catalyst
design and optimization. Example: Mass spectrometry techniques like
temperature-programmed desorption (TPD-MS) and reaction kinetics
analysis are used to study catalyst surface reactions, adsorption/desorption
phenomena, and catalyst deactivation mechanisms.
3. Environmental Monitoring: Mass spectrometry plays a crucial role in
environmental engineering and pollution control by analyzing air, water, soil,
and waste samples for contaminants and pollutants. It enables detection and
quantification of organic pollutants, heavy metals, and toxic substances,
helping assess environmental risks and comply with regulatory requirements.
Example: Mass spectrometry is used to analyze volatile organic compounds
(VOCs), polycyclic aromatic hydrocarbons (PAHs), and pesticides in
environmental samples, providing data for environmental impact
assessments and remediation efforts.
4. Materials Analysis: Mass spectrometry is employed for analyzing the
composition, structure, and properties of materials in fields such as polymers,
ceramics, and nanomaterials. It facilitates characterization of molecular
weight distributions, polymer additives, surface modifications, and
degradation products in materials. Example: Mass spectrometry techniques
like matrix-assisted laser desorption/ionization (MALDI-MS) and secondary
ion mass spectrometry (SIMS) are used to analyze polymer composition,
identify polymer additives, and study polymer degradation mechanisms.
5. Safety and Hazard Analysis: Mass spectrometry is used for safety and
hazard analysis in chemical processes, identifying and quantifying hazardous
compounds, reactive intermediates, and flammable gases. It helps assess the
risks associated with chemical reactions, storage, and handling, ensuring
workplace safety and compliance with safety regulations. Example: Mass
spectrometry is employed to detect and quantify toxic gases, volatile organic
compounds (VOCs), and explosive compounds in chemical plants and storage
facilities, enabling risk mitigation and emergency response planning.
These applications demonstrate the importance of mass spectrometry in
chemical engineering for process analysis, catalyst development,
environmental protection, materials science, and safety management.
CHALLENGES AND LIMITATIONS
In sample preparation, challenges often arise due to the complexity of the
samples, requiring extensive and meticulous preparation steps that can be
time-consuming and labor-intensive. Matrix effects can complicate
quantitative analysis by interfering with ionization or detection, leading to
signal suppression or enhancement. Instrument complexity poses challenges
in terms of setup, operation, and maintenance, requiring specialized expertise
and training. Data interpretation can be challenging due to the complexity of
mass spectrometry data sets, requiring advanced analytical skills and
computational tools. Sensitivity and dynamic range limitations may affect the
detection and quantification of analytes, particularly in samples with low
concentrations or wide concentration ranges. High instrumentation costs may
restrict access to mass spectrometry technology, especially for researchers
or organizations with limited resources. Finally, data processing and analysis
require specialized software and computational resources, which may not
always be readily available or user-friendly, posing challenges for efficient
data interpretation and sharing.
CONCLUSION
In conclusion, mass spectrometry stands as a cornerstone in chemical
engineering, offering invaluable insights into molecular structures,
composition, and interactions across various applications. Its ability to
analyze and characterize chemical compounds in real-time contributes to
process optimization, product quality control, and environmental monitoring.
However, despite its versatility and utility, mass spectrometry encounters
several challenges and limitations. These include complexities in sample
preparation, matrix effects, instrument operation, data interpretation,
sensitivity constraints, instrumentation costs, and data processing.
Addressing these challenges requires ongoing efforts in method
development, instrumentation improvement, and training programs to
enhance the capabilities and accessibility of mass spectrometry. By
overcoming these challenges, mass spectrometry will continue to play a
pivotal role in advancing research, innovation, and sustainability in chemical
engineering and beyond.
REFERENCES
1.
Mass Spectrometry for Chemical Engineers" by Gabor A. Somorjai and Y.
T. Lee, 1989, 1st Edition
2.
Process Analytical Chemistry" by Steven S. Cohen, 2016, 1st Edition
3.
Mass Spectrometry Handbook" edited by Mike S. Lee, 2012, 1st Edition
4.
Process Control Instrumentation Technology" by Curtis D. Johnson, 2018,
9th Edition
5.
Real-Time Analysis for Process Control by Mass Spectrometry" by M.J.
Oudenhoven and C.G. Bijlsma, 1995