Use of ferric ammonium sulfate in serum cholesterol determination.

To determine cholesterolin biologicalfluids,use of the ferric chloride-sulfuric acid reagent introduced by Zlatkis et al. (1) is relatively simple and reliable (2, 3), and the sensitivityof the reagent for cholesterol is four to five times greater than that of the Liebermann-Burchard reagent (2). However, Parekh and Jung (4) reported that hydrogen chloride is evolved during the ferric chloride-sulfuric acid reaction,leading to poor control of reaction temperature. In addition, the very deliquescent ferric chloride is tedious to handle. The ferricchloride-sulfuricacid method would thus be better if a nondeliquescent iron saltcould be substituted that forms no volatile compounds on reaction with sulfuric acid. We studied the possibility of using ferric ammonium sulfate.