Gas Chromatographic Separation and Identification of Jacaric and Punicic 2‐Ethyl‐1‐Hexyl Esters

The present study demonstrates the separation of a critical pair of conjugated linolenic acid (CLN) isomers—jacaric acid (JA; c 8, t 10, c 12‐18:3) and punicic acid (PA; c 9, t 11, c 13‐18:3)—on a 60‐m conventional Supelcowax 10 column. The alkyl esters of different alcohols (C 1 –C 8 ) of JA and PA were prepared and analyzed isothermally at 220, 230 and 240 °C. The adequacy of their separation was determined from the separation factors (α) and peak resolutions ( R s ). Acceptable resolution ( R s = 1.01) of JA and PA was obtained with their 2‐ethyl‐1‐hexyl ester derivatives at a column temperature of 230 °C. In addition, the Gibbs energy of transfer from solution to gas of the three double bonds ( Δ sln g G u ) could be used to describe the interactions of the double bond with the stationary phase. Characterization of 2‐ethyl‐1‐hexyl esters of Jacaranda mimosifolia seed oil at 230 °C demonstrates that the oil contains JA and α‐ and β‐calendic acid as a CLN without the presence of PA. The results suggested that JA could be resolved from PA on a 60‐m Supelcowax 10 column as the ethyl hexyl ester.