Chapter two

 

Analysis of Phospholipids by Liquid Chromatography

Coupled with On-Line Electrospray Ionization Mass

Spectrometry and Tandem Mass Spectrometry

 

Åsmund Larsen^a and Erlend Hvattum^b

 

^aGE Healthcare, Analytical Sciences R & D, Oslo, Norway, and ^bDepartment of Chemistry,

Biotechnology, and Food Science, Agricultural University of Norway, N-1432 Ås, Norway

 

Introduction

 

Biological Aspects

Phospholipids (PL) are the major constituents of most cellular membranes. In addition, they play important roles in the control of many biological processes and they are gaining importance in a variety of medical, biological, biotechnological, and industrial applications. An enormous variety of phospholipid structures is found in nature, exhibiting great diversity of both the apolar and the polar moieties of the lipid molecules. The phospholipids are divided into several distinct molecular classes, distinguished by the head group attached to the phosphate moiety. The main phospholipid classes are phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidylglycerol (PG), phosphatidic acid (PA), and cardiolipin (CL) (Scheme 2.1). Although sphingomyelin (SM) belongs to a separate class of lipids called sphingolipids, it is also an important constituent of plasma membranes of higher animals. Liquid chromatography-mass spectrometry (LCMS) analysis of sphingomyelins will therefore be partly covered in this chapter. Many molecular species are found in a single phospholipid class. They are characterized by the combination of fatty acyl residues attached to the sn-1 and sn-2 positions of the molecule and by the nature of the chemical linkage between the fatty acid (FA) chain and the sn-1 position of the glycerol backbone. Three types of linkage bonds are common: Acyl, ether, and vinyl–ether bonds. Ether and vinyl ether bonds are solely found in the sn-1 position and are most common among PC and PE (1). Phospholipids containing ether bonds, 1-O-alkyl, in the sn-1 position are called plasmanyl-PL, while phospholipids containing vinyl-ether bonds, 1-Oalkyl-1′-enyl, in the sn-1 position are known as plasmenyl-PL (or plasmalogens). Plasmanyl and plasmenyl phospholipids are especially abundant in heart, kidney, and central nervous system (CNS) (2–4).

Modern Methods for Lipid AnalysiS by Liquid Chromatography/ mass spectrometry and Related Techniques

Resources for Lipid Analysis in the 21st Century

Contact the authors:

 

Dr. Åsmund Larsen and Dr. Erlund Hvattum

GE Healthcare, Analytical Services

Oslo, Norway

 

E-mail:

Asmund Larsen: aa-lar@online.no

Erlund Hvattum:

erlend.hvattum@ge.com

This was a sample page from the book to give you an idea of what is discussed. 

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