Validation of an isotope dilution gas chromatography–mass spectrometry method for analysis of 7-oxygenated campesterol and sitosterol in human serum

Validation of an isotope dilution gas chromatography–mass spectrometry method for combined analysis of oxysterols and oxyphytosterols in serum samples

“…The toluene dissolved samples were loaded onto a silica cartridge and allowed to pass through the column by gravity force at room temperature. Cholesterol, and non-cholesterol neutral sterols, including plant sterols, were eluted from the column with 8 Â 1.0 mL 0.5% 2-propanol in n-hexane (v/v) followed by elution of the OCS and OPS with 3 Â 1.0 mL 30.0% 2-propanol in n-hexane (v/v) as described by Dzeletovic et al and Husche et al [36,37]. To decrease workup duration and to avoid autoxidation vacuum equipment (Marchery-Nagel, Düren, Germany) was employed to accelerate the washing procedure.…”

“…where D baseline is the difference in abundance for the baseline of n-decane used blank sample, D analyt presents the difference in abundance for the analyte and c analyte is the absolute concentration of the analyte, evaluated by GC [37].…”

“…The silylation reaction was performed by heating at 90°C for 1.5 h. The silylation-reagent was evaporated under a gentle stream of nitrogen and the residue was dissolved in 30 lL n-decane and transferred to an injection vial for GC-MS-SIM analysis. The authenticity of the compound was proven by the comparison of the spectra from the literature and quantification was performed by GC-flame ionisation detection (FID) as published previously [37].…”

Postprandial plasma oxyphytosterol concentrations after consumption of plant sterol or stanol enriched mixed meals in healthy subjects

“…7b-Hydroxy(OH)-campesterol, 7b-OH-sitosterol, 7-keto-campesterol and 7-keto-sitosterol were analyzed by gas chromatography-mass spectrometry (GC-MS-MS) according to the procedure as described by Husche et al [13] with minor modifications related to the use of a GC-MS triplequad instead of a GC-MS singlequad and are expressed as ng/mL.…”

Plant sterols: Friend or foe in CNS disorders?

“…Oxyphytosterols are present in plasma of healthy subjects and are markedly elevated in phytosterolemic patients [23,24]. However, controversy exist as to whether normo-phytosterolemic subjects treated with plant sterol enriched margarine have elevated levels of oxidized phytosterols [25,26].…”