Liquid chromatography-Fourier transform infrared spectrometric determination of cholesterol in animal greases

Stearic acid, cholesterol and cholesteryl palmitate have been separated in less than 14 min by liquid chromatography on a column (3.9 mm i.d.×150 mm) of Nova-Pack C18 (5 μm) using chloroform–acetonitrile (45 : 55) as mobile phase pumped at 0.5 ml min−1; Fourier transform infrared (FTIR) spectrometry was employed for both, general detection at 2868 or 2855 cm−1 and selective detection at 3285 cm−1 for stearic acid and 3526 cm−1 for cholesterol. In all cases a baseline established at 3900 cm−1, 9-point smoothing and chromatographic peak height measurements were used. The method has been validated by application to the determination of cholesterol in animal greases and fish oils. Samples, previously saponified with KOH, were extracted with petroleum ether, redissolved in chloroform and the final solution injected into the chromatographic system. The percentage recoveries were 95–99% for samples spiked with cholesterol and 100–102% for samples spiked with cholesteryl palmitate.