Vicinally unsaturated hydroxy acids in seed oils

Summary The interference of certain unsaturated hydroxy acids in the Durbetaki method of epoxide determination has been demonstrated. The concentrations of these constituents were determined concurrently with those of epoxy components by measurement of the near infrared spectra of samples before and after treatment with anhydrous ethereal hydrogen chloride. The individual hydroxy esters were separated and isolated from samples of mixed esters by thinlayer chromatography. GLC of these esters resulted in their alteration to conjugated trienoates and gave proof of their conjugated diene hydroxyl structure. Thin‐layer chromatographic and infrared studies verified the Trans‐trans diene unsaturation of the acid from Dimorphotheca aurantiaca oil and showed that the other hydroxy compounds examined have a cistrans diene system. These data suggest that the seed oils of Artemisia absinthium, Calliandra eriophylla, Balanites aegyptica, Cosmos bipinnatus, and Helianthus annuus contain 9‐hydroxy‐ trans ‐10‐ cis ‐12‐ and 13‐hydroxy‐ cis ‐9‐ trans ‐11‐octadecadienoic acids.

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