Determination of cholesterol in milk fat by gas chromatography with direct injection and sample saponification

Summary A rapid and direct gas chromatographic (GC) method for determining free cholesterol in milk fat using a capillary column and programmed-temperature vaporizer-injector was assayed. It was compared with other procedures involving saponification of fat, solvent extraction of unsaponifiable matter — with and without fractionation by thin-layer chromatography — and transformation of sterols into silyl derivatives prior to GC analysis. This paper proposes an alternative to other published procedures. Repeatability of the method was assessed and the coefficient of variation determined as 2.1 %. The alternative saponification method exhibited comparable accuracy (coefficient of variation=1.8 %). Recovery ranged from 99.1 % to 105.6 %.