COMPARATIVE-EVALUATION OF 3 METHODS FOR T HE DETERMINATION OF CHOLESTEROL IN EGG-YOLK

A comparative evaluation of three methods for the determination of cho lesterol in egg yolk was conducted. The methods were: (a) the colorime tric method of Bohac et al. which involves a reaction with saturated a cetic acid, ferrous sulfate and concentrated sulfuric acid; (b) the Ad olfo Lutz Institute's method, also colorimetric, which utilizes glacia l acetic acid, acetic anhydride and concentrated sulfuric acid; and (c ) a high performance liquid chromatographic (HPLC) method, the conditi ons for which were established in the present work. For the latter met hod, a C-18 column was used, with acetonitrile-isopropanol (1:1) as mo bile phase and a diode array detector; quantification was carried out by external standardization. The cholesterol concentrations obtained b y the HPLC method (10.1 = 0.5 mg/g yolk) and that of Bohac et al. (11. 0 +/- 1.0 mg/g yolk) did not differ significantly at 5% level. The col orimetric method of the Adolfo Lutz Institute overestimated the choles terol contents (16.8 +/- 0.9 mg/g yolk).