DETERMINATION OF CHOLESTEROL IN MILK-FAT BY GAS-CHROMATOGRAPHY WITH DIRECT-INJECTION AND SAMPLE SAPONIFICATION

A rapid and direct gas chromatographic (GC) method for determining fre e cholesterol in milk fat using a capillary column and programmed-temp erature vaporizer-injector was assayed. It was compared with other pro cedures involving saponification of fat, solvent extraction of unsapon ifiable matter - with and without fractionation by thin-layer chromato graphy - and transformation of sterols into silyl derivatives prior to GC analysis. This paper proposes an alternative to other published pr ocedures. Repeatability of the method was assessed and the coefficient of variation determined as 2.1 %. The alternative saponification meth od exhibited comparable accuracy (coefficient of variation = 1.8 %). R ecovery ranged from 99.1 % to 105.6 %.