Determination of vitamin E. A sample volume of 0.1 ml of hexane extract of seeds containing vitamin E was mixed in a test tube with 1 ml of reagent solution and incubated at 37°C for 90 min with vigorous shaking. Absorbance of the aqueous phase at 695 nm was measured against the appropriate blank. A typical blank contained 1 ml of reagent solution and 0.1 ml of pure hexane, and it was incubated under the same conditions as the samples.