DETERMINATION OF HIGHER FATTY-ACIDS IN OILS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

A system of high-performance liquid chromatography with electrochemica l detection was developed for the separation and determination of high er fatty acids. An octadecylsilica (ODS) column was used as the statio nary phase and an ethanol-acetonitrile (10:90) mixture as the mobile p hase. The eluate was mixed with a quinone solution which was composed of 6 mM 2-methyl-1,4-naphthoquinone and 76 mM LiClO4 in ethanol-aceton itrile (10:90) through a mixing coil. Peak height for higher fatty aci ds measured at -415 mV vs. saturated calomel electrode (SCE) was linea r against the amount of acid between 20 and 1200 pmol. Free fatty acid s in various oil samples were determined by this method, which was fou nd not only sensitive and reproducible but also a simple means for sep arating and determining free fatty acids in oils.