20.25 Grams (41.8 mmoles) of cholesteryl hydrogen succinate (sold by Aldrich Chemicals) and 19.8 ml (83.4 mmoles) of tributylamine were dissolved in 540 ml of Dioxane. The solution was cooled and treated with 5.3 ml (5.7 g, 41.7 mmoles) of isobutyl chloroformate. The reaction was permitted to proceed in the cold for 30 minutes, and then the mixture was added in one portion to a stirred, cooled solution of 50.0 g (41.7 moles) of bovine serum albumin in 1100 ml of water, 750 ml of p-dioxane, and 50 ml of 1 N NaOH. Stirring and cooling was continued for 6 hours. The material was then dialyzed against water and lyophilized to yield a stable white powder useful as a cholesterol standard.
