Comparison of two different methods for the separation of lipid classes and fatty acid methylation in reindeer and fish muscle

In the present study different methods for the separation of lipid classes and methylation were compared and evaluated for method optimisation in muscle tissue. Fish and reindeer muscle were tested as fish represents a high proportion of polyunsaturated FA (PUFA) and reindeer a moderate amount of PUFA. Lipids were separated either by solid phase extraction (SPE) into neutral (NL) and polar lipids (PL) or by thin layer chromatography into triacylglycerols (TAG) and phospholipids. All fractions were methylated with or without boron trifluoride (BF3). The two different separation methods showed differences between PL and phospholipids, while TAG and NL were largely similar. Methylation method did not lead to important differences when comparing within the different separation methods, though methylation with BF3 generally resulted in similar or higher values of methylated FA, indicating a more complete methylation. The content of PUFA in the muscle tissue did not affect these outcomes. Separation of lipids by SPE, followed by methylation with BF3 was judged to be the best overall method, though not suitable for analysis of samples with labile fatty acids.

► Separation method showed significant effects for PL and phospholipids.
► Methylation method did not cause differences within the separation methods.
► Methylation with BF3 indicated a more complete methylation.