20. Mass Spectrometry 1

Introduction to Mass Spectrometry

  • Lecture presented by Ben Collins from Queen’s University Belfast.

  • Course: BIO2102 – Experimental Biochemistry

Learning Outcomes

Students should be able to:

  1. Explain the basics of mass spectrometry.

  2. Describe the fundamental approaches to peptide/protein analysis by mass spectrometry.

Mass Spectrometry Outline for BIO2102

Lecture Schedule

  • Lecture 1: Mass spectrometry basics.

  • Lecture 2: Fundamentals of protein and peptide analysis by mass spectrometry.

Today's Lecture Outline

  • Background and basic principles.

  • Ionization techniques:

    • Focus on MALDI (Matrix-Assisted Laser Desorption/Ionization)

    • Focus on Electrospray Ionization.

  • Mass analysis techniques:

    • Focus on Quadrupoles.

    • Focus on Time-of-Flight (TOF).

  • Detection techniques:

    • Mass spectra concepts, charge states, and isotope distribution.

    • Overview of Tandem mass spectrometry.

History of Mass Spectrometry

  • Early 1900s: Development of mass spectrometry instrumentation.

    • Initial studies involved anode/cathode rays and isotopes.

  • Late 1950s: Mass spectrometry for organic chemistry:

    • Focus on small organic molecules (< 500 Da).

  • Mid 1980s: Expansion to biological mass spectrometry:

    • Methods for large, non-volatile biomolecules (e.g., peptides, proteins).

    • Influential ionization methods include Fast Atom Bombardment (FAB) and Thermospray (TSI).

    • Newer techniques: Electrospray Ionization (ESI), MALDI.

  • Proteomics revolution (early 1990s):

    • Significant advancements in electronics, automation, informatics, and data acquisition methods.

Nobel Prizes in Mass Spectrometry

  • Key Nobel Laureates:

    • Joseph John Thomson (1906): For investigations on conduction of electricity by gases.

    • Francis William Aston (1922): For discovery of isotopes and mass spectrum.

    • Wolfgang Paul (1989): For development of the ion trap technique.

    • John Bennet Fenn & Koichi Tanaka (2002): For development of ESI and MALDI methods for biological macromolecules.

General Applications of Mass Spectrometry

Pharmaceutical Applications

  • Bioavailability and drug metabolism studies.

  • Characterization of drugs and degradation products.

  • Screening and identifying drug targets.

Biomolecule Applications

  • Analysis of proteins, peptides, and oligonucleotides.

Environmental Analysis

  • Tracking organic pollutants and soil contamination.

Forensic Applications

  • Linking suspects to crimes and detecting narcotics.

  • Sports anti-doping analysis.

Security Applications

  • Detection of explosives and chemical warfare agents.

Food & Beverage Analysis

  • Detection of natural compounds and adulterants.

Principle of Mass Spectrometry

  1. Ionization: Convert sample components into charged ions.

  2. Gas Phase Transition: Volatilize the sample components.

  3. Ion Manipulation: Use electric or magnetic fields to separate ions based on mass/charge ratio (m/z).

  4. Detection: Count and register separated ions.

Mass Spectrometer Components

  • Source: Ionization techniques (e.g., ESI, MALDI).

  • Analyzer: Various types (Quadrupole, TOF, etc.).

  • Detector: Converting ions to electrons (e.g., MCP, charge induction).

Biological Mass Spectrometry Revolution (1990s)

  • Enabled analysis of large biomolecules with soft ionization techniques.

    • MALDI and Electrospray Ionization for proteins and peptides.

Ionization Methods

Electrospray Ionization (ESI)

  • Produces ions from liquid solutions via a strong electric field.

  • Operates predominantly in positive mode for peptides.

Matrix-Assisted Laser Desorption/Ionization (MALDI)

  • Vaporizes non-volatile samples from solid to gas state.

Mass Analysis Techniques

Time-of-Flight (TOF)

  • Dependent on ion size: larger ions travel slower, taking longer to traverse the drift zone.

  • Kinetic energy distribution defined by charge and voltage.

Quadrupole Mass Analyzer

  • Functions as a filter, analyzer, or trap.

  • Operates based on frequency of electrical switching.

Detection in Mass Spectrometry

  • Converts ion signals to electrical signals for detection.

  • Common detection methods: Impact (MCP), inductive detection.

Summary of Mass Spectrometry Basics

  • Involves three key stages: ionization, analysis, and detection.

  • Different technologies correspond to each stage and can be combined.

  • Next lecture will detail approaches for peptide and protein analysis.