How many mass spectrometers are enough? Adventures in multiple parallel mass spectrometry

Authors: Byrdwell, W Craig

Submitted to: International News on Fats, Oils and Related Materials
Publication Type: Trade Journal
Publication Acceptance Date: 2/4/2013
Publication Date: 5/1/2013
Citation: Byrdwell, W.C. 2013. How many mass spectrometers are enough? Adventures in multiple parallel mass spectrometry. International News on Fats, Oils and Related Materials. 24(5):312-316.

Interpretive Summary: This is an invited feature article targeted at oil chemists that describes how more than one mass spectrometer simultaneously in parallel can be used for chemical analysis without excessive expense or difficulty. A mass spectrometer is an instrument that measures the masses of molecules. This article describes the first and other significant milestone publications in the 'dual parallel mass spectrometry', in which two mass spectrometers are used together, and 'triple parallel mass spectrometry', in which three mass spectrometers are used together. It describes the benefits of obtaining more than one type of data simultaneously in a single run, instead of having to run samples several times to obtain complementary data. Tips and hints at how to accomplish these types of experiments using simple off-the-shelf components are given.

Technical Abstract: Analysis of lipid mixtures has always been a complicated undertaking due to the variety of lipid classes that may be present (fatty acids (FA), triacylglycerols (TAG), phospholipids (PL), sterols (ST), and others) and the large number of molecules within each class. The variety of combinations of fatty acids with different chain lengths and degrees of unsaturation (i.e. molecular species) that can be present in each class is extensive, which is further complicated by the different combinations of how they are arranged on the glycerol backbone (for TAG and glycero-PL) to give different regioisomers, as well as different double bond isomers (e.g. omega-3 versus omega-6, etc.). We have repeatedly demonstrated the use of two or three mass spectrometers in parallel for structural elucidation of lipid various lipid classes, using atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) and electrospray ionization (ESI) MS. The benefits and difficulties of implementing a 'multiple parallel mass spectrometry' approach are described, and the first and other significant milestones in dual parallel mass spectrometry and triple parallel mass spectrometry are shown. Among the points demonstrated are these: • Using more than one mass spectrometer in parallel is not impractical and expensive. • Using multiple ionization methods reduces uncertainty and provides more and complementary information in less time. • New methods allow time to be spent interpreting data and doing other high value tasks, instead of doing wet chemistry.