ガスクロマトグラフィー/質量分析法によるヒト脳脊髄液中の24S-ヒドロキシコレステロールの定量

A simple pretreatment method for the determination of 24S-hydroxycholesterol in human cerebrospinal fluid by gas chromatography/mass spectrometry (GC/MS) has been developed. Esterified cholesterol was saponified by a high concentration of potassium hydroxide (25 M, 1 mL) in a small volume (10 mL) of a conical test tube with a stopper made of glass. Next, free cholesterol was extracted with a small volume of n-hexane. The combined extracts obtained by the twice extraction were then applied on a silica cartridge for solid-phase extraction. A slight amount of 24S-hydroxycholestertol was separated from a large amount of cholesterol using n-hexane and ethylacetate as an elution solvent. 24S-hydroxycholestertol and 27-hydroxycholesterol-26,26,26,27,27-D5 as an internal standard were converted to trimethylsilyl ethers by the trimethylsilyl (TMS) reagent, and then the TMS derivatives were determined by GC/MS. The method was successfully applied to the determination of 24S-hydroxycholestertol in human cerebrospinal fluid from patients of non-neurodegenerative disorders. The pretreatment method reported here was simple and useful for one multi-specimen material pretreatment.