MSACL 2017 EU Abstract

Basics of MS/MS

Laura Owen (Presenter)
University Hospital of South Manchester

Bio: I have worked at the University Hospital of South Manchester since 2003 developing new LC-MS/MS assays. My area of interest is endocrinology. I also oversee the day-to-day running of the laboratory's LC-MS/MS section which has 6 analysers and over 20 routine assays.

Authorship: Laura Owen
University Hospital of South Manchester, Manchester, UK

Short Abstract

Tandem mass spectrometry is a technique that is often used in clinical laboratories for a wide variety of analytes. Its superior specificity is a major consideration which has led to the increase in its use over the last 10-15 years. Ionisation of the analyte of interest is essential to its measurement using this technique, with the main principle being the mass-to-charge ratio, referred to as the m/z. Understanding how a tandem mass spectrometer works and the principles behind its operation are invaluable for those interested in method development and troubleshooting.

Long Abstract

This session is aimed at those with little or no mass spectrometry experience. An overview of the workflow of a mass spectrometry will be described. This will then be followed by an in-depth description of how a tandem mass spectrometer works. A mass spectrometer operates based on the mass to charge ratio of an analyte ion. Each of the different components of a mass spectrometer will be explained and how the ions move though these will be demonstrated using animations and diagrams. Basic concepts such as tuning and resolution will also be described to help any new users understand these terms.

Electrospray ionisation is probably the most common technique used for ionisation of analytes by tandem mass spectrometers. Ion suppression is a matrix affect which can reduce the efficiency of the ionisation process. The main data acquisition mode for quantitative assays is multiple reaction monitoring (MRM) however tandem mass spectrometers do have the ability to be used in other modes for specialist techniques.

Internal standards are an essential component of a quantitative assay as it helps to compensate for any variations in both extraction and ionisation efficiency. Internal standards may vary from structural analogues or stable isotopes such as those containing deuterium, 13C or 15N. There are limitations with even some stable isotopes so this session should enable new users to consider this when selecting internal standards for their assay.

Learning objectives of this session:

1. Understand how a tandem mass spectrometer works

2. Understand ionisation techniques

3. Know what ion suppression is

4. Understand the advantages and disadvantages of various types of internal standards

References & Acknowledgements:

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