QUANTITATIVE PRECIPITATION OF VARIOUS 3β-HYDROXYSTEROLS WITH DIGITONIN

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Abstract
Conditions are described for the quantitative precipitation of nine 3β-hydroxysterols with digitonin. After removal of excess reagent, the sterol and digitonin moieties are dissolved in a known volume of dry pyridine. An aliquot of the pyridine solution is processed to give a measure of total 3β-hydroxysterol by estimating the digitonin moiety with the use of anthrone. From another aliquot, the free sterols may be regenerated for differential-photometric and gas–liquid or thin-layer chromatographic analysis.Recoveries for each sterol at three levels of concentration were as follows: β-sitosterol, 98.6 ± 1.8% (mean and S.D.); campesterol, 99.1 ± 1.9%; stigmasterol, 98.9 ± 1.7%; stigmastanol, 99.1 ± 1.9%; cholesterol, 100.1 ± 1.5%; cholestanol, 100.8 ± 1.3%; coprostanol, 93.6 ± 1.6%; Δ7-cholestenol, 98.5 ± 1.8%; and 7-dehydrocholesterol, 91.9 ± 1.8%.