When required, the extraction solvent was supplemented with BHT (1 mg/ml) or spiked with a-, g-, and d-tocopherol or the internal standard a-tocopherol acetate.
After centrifugation at 10,000g for 15 min, the supernatant was transferred to new tubes. The pellet was resuspended and homogenized in another volume of solvent and centrifuged once more. The supernatant was combined with