Basics of Mass Spectrometry in the Clinical Laboratory

Basics of Mass Spectrometry in the Clinical Laboratory
Deborah French Ph.D., DABCC, FACB
Assistant Director of Chemistry Director of Mass Spectrometry
UCSF Clinical Laboratories San Francisco, CA
Mass Spectrometry in the Clinical Laboratory: Best Practices and Current Applications October 9-10 2014

Learning Objectives
After this presentation, you should be able to:
1. Explain the principles of mass spectrometry 2. Describe the different mass spectrometers available 3. Compare the data acquisition capabilities of the different
instruments 4. Evaluate which mass spectrometer would best suit the
applications required in your laboratory

Overview
 What is a mass spectrometer and what is mass spectrometry?  Ionization techniques  Mass analyzers
 Single quadrupole, triple quadrupole, ion trap  SIM, SRM, ion ratios and product ion spectra for confirmation
 High resolution mass analyzers and data acquisition  Nominal mass vs exact mass
 Comparison of mass analyzers  Other considerations for implementation of mass spectrometry  What’s still needed?  Conclusions

What is a mass spectrometer?
 an instrument that essentially weighs molecules

What is mass spectrometry?
 a technique that measures molecules in the gas phase  charged species are generated and sorted based on the mass to charge ratio

What are the components of a mass spectrometry system?

Ionization
Ion Source
Components of sample are ionized (become charged)

Mass Sorting
Mass Analyzer
Ions separated by mass (m) to charge (z) ratio (m/z)

Detection
Ion Detector
Detects ions

Inlet
Sample is introduced into mass
spectrometer (liquid
chromatography)

Ionization
 have to convert flow of liquid from liquid chromatography system to gas before mass spectrometry analysis  different forms of liquid to gas ionization
 electrospray ionization (ESI)  atmospheric pressure chemical ionization (APCI)  atmospheric pressure photo ionization (APPI) (not
commonly used in clinical laboratories)

Convert flow of liquid from LC column to mist in order for ionization to occur

Flow from LC column

Converted to mist in ionization source

Pictures courtesy of Dr. Tom Annesley

Electrospray Ionization (ESI)
Atmospheric pressure
www.bris.ac.uk/nerclsmsf/techniques/hplcms.html

Atmospheric Pressure Chemical Ionization (APCI)
www.bris.ac.uk/nerclsmsf/techniques/hplcms.html