[Determination of cholesterol and its six metabolism markers in serum by high performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry]

A method for the determination of cholesterol and its six metabolism markers (desmosterol, lathosterol, campesterol, stigmasterol, β-sitosterol, squalene) in serum by high performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry (HPLC-Q/Orbitrap HRMS) was developed. The sample was ultrasonically extracted with acetonitrile. The separation was performed by using 95%(v/v) methanol-acetonitrile (2:8, v/v)-5%(v/v) water as the mobile phase. Isocratic elution was performed at a flow rate of 0.4 mL/min on an Acquity UPLC BEH C₁₈ column (100 mm×2.1 mm, 1.7 μm) in 15 min. The atmospheric pressure chemical ionization (APCI)/positive mode was used in the MS detection. Cholesterol and its six metabolism markers were qualitatively and quantitatively determined by using the full MS scan/date dependent MS² (Full MS/dd MS²) mode. The resolution of the precursor mass was 70000 FWHM, while the resolution of the product mass was 17500 FWHM. The correlation coefficients (r²) of all the seven target compounds were no less than 0.992 in the linear range. The limits of detection were between 0.8 μg/L and 62.1 μg/L, the recoveries were in the range of 82.1%-97.5% with the relative standard deviations in range of 1.6%-7.4%. The method is accurate, simple, and rapid, and can be used for the determination of cholesterol and its six metabolism markers in serum.