Measurement of ethanolamine- and serine-containing phospholipids by high-performance liquid chromatography with fluorescence detection of their Dns derivatives.

We describe a liquid chromatographic procedure for the analysis of amino group-containing phosphoglycerides in tissue. The total lipid extract is derivatized with Dns-chloride at 50 degrees C for 3 h. Dns derivatives of phosphatidylethanolamine, lysophosphatidylethanolamine, phosphatidylserine and lysophosphatidylserine are separated by a silica gel column with gradient elution. The eluate is monitored by fluorescence detection at 342 nm (excitation) and 500 nm (emission). Ethanolamine and serine plasmalogens can be determined indirectly by converting their derivatives into Dns-lysophosphatidylethanolamine and Dns-lysophosphatidylserine with exposure to HCl fumes. The optimal sample size for derivative formation and analysis by this method is between 1 and 10 nmol of phospholipids (30 and 300 ng of lipid phosphorus), although the lower limit of detection is about 20 pmol. By analyzing the total lipid extract of rat brain we showed that the method was applicable to the quantitative analysis of amino group-containing phosphoglycerides in tissue samples.