LC-MS/MS Determination of Cholesterol in Fats or Oils of Animals or Vegetables with Solid Phase Extraction

LC-MS/MS was applied to the determination of cholesterol in fats or oils of animals or vegetables with solid phase extraction. The sample was saponified by ethanol and potassium hydroxide, and extracted with mixture of petroleum ether and ethyl ether(1+1), and then purified by silica gel solid phase extraction column. Zorbox SB C₁₈ chromatographic column was used as stationary phase, and the mixture of 5 mmol·L^-1 ammonium acetate solution and acetonitrile-methanol(1+1) solution mixed in different ratios was used as mobile phase in gradient elution. ESI⁺ and multi-reactions monitor mode were adopted in MS/MS. Internal standard method was used for quantitative. Linear relationship between values of peak area and mass concentration of cholesterol was kept in the range of 0.1-5.0 mg·L^-1, with detection limits (3S/N) of cholesterol in fats or oils of vegetables or fats or oils of animals of 0.02, 0.2 mg·kg^-1, respectively. Tests for recovery were made by standard addition method at the concentration levels of 0.5,1.0,5.0 mg·kg^-1, giving values of recovery and RSD's (n=6) in the ranges of 85.2%-92.0% and 3.6%-9.4% respectively.