Effect of unusual acids on selected seed oil analyses

In the course of chemical compositional studies on seed oils from more than 2600 species of uncultivated plants, a number of new acids were isolated and structurally characterized at our laboratory. Also included in the studies were many fatty acids previously identified but not widely distributed or readily available. Oils containing unusual functional groups often gave unexpected responses to analytical procedures in frequent use. To exemplify the analytical results, data are presented relative to behavior of oils containing oxygenated fatty acids, cyclopropene rings, unusual types and positions of unsaturation, differing chain length, and sundry combinations of these, in the following procedures: Determinatio of polyunsaturated acids by ultraviolet spectrophotometry; iodine value versus refractive index plot to single out unusual oils; oxirane oxygen by HBr titration; gas‐liquid chromatography; infrared, and nuclear magnetic resonance spectroscopy; and lipoxidase assay. Preliminary experimentation on an automatic analytical hydrogenation apparatus indicates good potential, in its aplication to both usual and unusual oils, for a rapid determination of total unsaturation with acceptable accuracy and precision.