Determination of serum cholesterol by stable isotope dilution method using discharge-assisted thermospray liquid chromatography/mass spectrometry.

A discharge-assisted thermospray (plasmaspray) liquid chromatography/mass spectrometric method for the determination of total serum cholesterol is described. The method incorporates stable isotope dilution using (3,4-13C)cholesterol as an internal standard. Liquid chromatographic separation is performed using methanol as a flow solvent and effluents are directly introduced to the mass spectrometer. [MH-H2O]+ ions are monitored during liquid chromatography/mass spectrometry using the selected ion monitoring method. Satisfactory agreement between the analytical result and the certified value of the National Institute of Standards and Technology (formerly National Bureau of Standards) standard reference material serum is obtained with a relative standard deviation of 0.6%.