Gas chromatographic equivalent chain lengths of isomeric methyl octadecenoates and octadecynoates

Equivalent chain lengths (ECL) have been determined for methyl cis ‐5‐, 6‐, 8‐, 9‐, 10‐, 11‐, 12‐, 15‐; trans ‐2‐, 3‐, 5‐, 6‐, 8‐, 9‐, 10‐, 11‐, 12‐, 15‐; and 17‐octadecenoates and for methyl 5‐, 6‐, 8‐, 9‐, 10‐, 11‐, 12‐ and 15‐octadecynoates on diethylene glycol succinate, polyphenyl ether and 100% β‐cyanoethylmethylsiloxane capillary columns. Although the levels of ECL values differed, the patterns were similar for the different substrates. For methyl octadecenoates, except for 2‐isomers, ECL generally increased with distance of double bond from the ester group but changed little from the 6 to the 10 position. Differences were smaller among isomeric trans esters than among cis . In methyl octadecynoates there was a greater and more regular increase of ECL occurred as the triple bond moved away from the ester group.