Abstract
Detection and determination of Dowtherm A in fatty oils by means of gas chromatography and spectrophotometry have been studied. Gas chromatography of the unsaponifiable materials extracted can be used for determination of Dowtherm A down to the 5 ppm level in 10 g refined soybean oil. Separation of hydrocarbon fraction from the unsaponifiable materials with thin-layer chromatography followed by gas chromatography is useful for the determination of Dowtherm A in fatty oils in concentrations as low as 0.2 ppm. When SE-30 column is used, Dowtherm A indicates two peaks for diphenyl and diphenylether at column temperature 130°C, and a single peak at column temperature above 190°C. Dowtherm A is detected by the retention times and area ratios of diphenyl and diphenylether in the gas chromatography.
