PURIFICATION OF FATTY-ACID ETHYL-ESTERS BY SOLID-PHASE EXTRACTION ANDHIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

We have developed a two-step method to purify fatty acid ethyl eaters (FAEE) using solid-phase extraction (SPE), with a recovery of 70+/-3% (mean+/-S.E.M.) as assessed using ethyl oleate as a recovery marker fr om a standard lipid mixture in hexane. The first step of the SPE proce dure involves application of a lipid mixture to an aminopropyl-silica column with simultaneous elution of FAEE and cholesteryl esters from t he column with hexane. Gas chromatographic analysis of FAEE without in terference from cholesteryl esters may be performed using the eluate f rom the aminopropyl-silica column, thus eliminating the need for an oc tadecylsilyl (ODS) column in this case. The FAEE can then be separated from the cholesteryl esters, if necessary, by chromatography on an OD S column and elution with isopropanol-water (5:1, v/v). Both the amino propyl-silica and ODS columns were found to be effective for up to fou r uses. To permit isolation of specific FAEE species following isolati on of total FAEE by the two-step SPE method, we have also developed a purification scheme for individual FAEE by high-performance liquid chr omatography (HPLC). Thus, this simple method allows for reproducible i solation of total FAEE by SPE and isolation of individual FAEE species by HPLC.