Analysis of fatty acids by capillary electrophoresis with indirect UV detection

Abstract

An analysis of the long-chain fatty acids in some saponified vegetable oils (olive, rice bran and linseed oils) and salmon roe phospholipids was carried out using capillary zone electrophoresis (CE) with indirect UV detection at 254 nm. Adenosine monophosphate (AMP) was used as an indirect UV detection reagent. The electrolyte consisted of 40 mM Tris buffer and 2.5 mM AMP in N-methylformamide/dioxane/water (5 : 4 : 1, v/v/v, for vegetable oil fatty acids; 4 : 6 : 1 for fish oil fatty acids). A satisfactory separation of an approximately 20 fmol mixture of palmitic (16 : 0), stearic (18 : 0), oleic (18 : 1n-9), linoleic (18 : 2n-6) and linolenic (18 : 3n-3) acids from vegetable oils was achieved within 25 min. Icosapentaenoic acid (20 : 5n-3) and docosahexaenoic acid (22 : 6n-3) were also completely resolved within 50 min, although some peak overlappings were observed in the fish sample. The fatty acid compositions (mol%) obtained by CE were in good agreement with those determined by HPLC. Thus, the CE method employed in this study would be useful for determining the composition of saturated and unsaturated fatty acids from biological samples.