Dual parallel mass spectrometry for lipid and vitamin D analysis

Authors: Byrdwell, W Craig

Submitted to: Journal of Chromatography A
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2009
Publication Date: 6/18/2010
Citation: Byrdwell, W.C. 2010. Dual parallel mass spectrometry for lipid and vitamin D analysis. Journal of Chromatography A. 1217(25):3992-4003.

Interpretive Summary: Mass spectrometry is a powerful chemical technique that allows a huge variety of very small molecules to be identified by their weight (masses). However, there are always trade-offs that must be made on the type of analysis performed, due to limitations in the number of experiments that a single instrument can perform in a given amount of time. To overcome some of these limitations, we demonstrate the use of two mass spectrometer instruments, each doing different types of experiments at the same time, to get the maximum amount of information from a limited amount of sample.

Technical Abstract: There are numerous options for mass spectrometric analysis of lipids, including different types of ionization, and a wide variety of experiments using different scan modes that can be conducted. Atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) provide complementary types of information that are both desirable. However, the duty cycle of the mass spectrometer places limits on the number of experiments that can be performed, and instruments usually employ only one type of ionization at a time. This work describes the approaches we have used that employ two mass spectrometers in parallel or in a column-switching configuration that allow multiple ionization modes and types of experiments to be conducted simultaneously during a single chromatographic run. These data demonstrate how use of two systems can reduce or eliminate the need for repeat injections and repetitive experiments. Approaches are described that employ two mass spectrometers connected in parallel as detectors for a single chromatographic system (LC1/MS2) or that employ two liquid chromatographs and two mass spectrometers in a column switching arrangement (LC2/MS2). Examples of LC1/MS2 analyses of triacylglycerols, sphingolipids, and vitamin D are given, as well as an example of an LC2/MS2 experiment used to analyze both polar and non-polar lipids in a total lipid extract.