Quantification of long-chain aldehydes by gas chromatography coupled to mass spectrometry as a tool for simultaneous measurement of plasmalogens and their aldehydic breakdown products.

The cleavage of the specific vinyl ether linkage at the sn-1 position of plasmalogens leads to the formation of two products: the 1-lyso-2-acyl glycerophospholipid and a long-chain fatty aldehyde. Plasmalogens are measured by quantifying one of these two products. In this paper, we describe a rapid and sensitive procedure for measuring plasmalogens via quantification of long-chain fatty aldehydes. After lipid extraction, the sn-1 vinyl ether bond of plasmalogens is cleaved by acidic hydrolysis. The produced aldehydes are then derivatized with (pentafluorobenzyl)hydroxylamine hydrochloride and analyzed by gas chromatography/mass spectrometry in selected-ion mode. Plasmalogens are then indirectly quantified by subtracting the free aldehydes obtained without prior HCl treatment from the total aldehydes obtained after acidic hydrolysis. This method is applied to three rat brain areas selected for this study. Two of these are affected in neurodegenerative diseases (cerebral cortex and hippocampus) and one is rich in white matter (cerebellum). In comparison to other procedures, the advantages of this method are not only its usefulness in plasmalogen quantification but also the identification of aldehydic breakdown products.