Comparison of three solid-phase extraction methods for fatty acid analysis of lipid fractions in tissues of marine bivalves.

Objective of this study was to investigate the effect of using pre-packed Si (Si), manually packed silica hydrated with water (Si-H(2)O) and pre-packed aminopropyl-bonded silica (NH(2)), at various mass ratios of lipid to sorbent, on the recovery of polar lipids following the solid-phase extraction (SPE) of a standard mixture of lipids. We also applied SPE using these sorbents to the separation of lipids from oyster tissues and compared the fatty acid (FA) composition of each fraction. Recoveries of phospholipids after SPE using Si increased with an increasing ratio of lipid to sorbent. Although the use of Si-H(2)O improved the recovery of polar lipid compared to that obtained on Si, the neutral lipid from gills and muscles of oyster showed distorted FA compositions presumably due to a leakage of polar lipids. Finally, NH(2) eluted with methanol provided good recoveries of phospholipids from the standard mixture; although polar lipids of oyster tissues showed a reduction in 20:4n-6 and MUFA likely due to the selective retention of acidic phospholipids.