Concurrent C18 Solid Phase Extraction of Platelet Activating Factor (PAF) and Arachidonic Acid Metabolites

Abstract Concurrent solid phase extraction of arachidonic acid metabolites and platelet activating factor in human vein umbilical endotelial incubates has been achieved on commercial C18 reversed phase cartridges. Control of sample pH, elution solvents and C18 adsorbent material are important for selective recoveries. Samples were acidified at pH=4.0 and processed through the C18 cartridges which were washed with 10 ml of water/methanol 9/1,10 ml of water at pH=4.0 and 20 ml of petroleum ether. Arachidonic acid metabolites and platelet activating factor adsorbed on the solid phase material were sequentially separated by elution with 4.5 ml of methyl formate and 4.5 ml of methanol, respectively. Recoveries thus obtained were 65.0 ± 2.5%, 89.1 ± 4.6%. 91.1 ± 7.5%, 94.8 ± 1.6 % for PAF, 6-keto PGF1α, 15-HETE and PGE2 respectively. The method was also compared with the classical Bligh & Dyer liquid-liquid extraction procedure.