Determination of total cholesterol in serum by isotope dilution liquid chromatography tandem mass spectrometry / 中华检验医学杂志

ABSTRACT

Objective To develop a method for the determination of total cholesterol in serum by isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS).Methods Serum samples were supplemented by addition of [3,4-~(13)C_2]-cholesterol,hydrolyzed with alcoholic sodium hydroxide and oxidized into cholest-4-ene-3,6-dione by chromic acid.The oxidation products were analyzed by LC/MS/MS using atmospheric pressure chemical ionization (APCI) source and detection modes of multiple reaction monitoring (MRM) and single ion recording (SIR).Signals (peak areas) of the internal standard were corrected for the contributions of cholesterol and the signal ratios of cholesterol to internal standard for the calibrations were linearly regressed against cholesterol concentrations.The resulted regression equation was used for the calculation of serum cholesterol concentrations.Results The correlation coefficients between the peak area ratios and cholesterol concentrations were 0.999 9 and higher.Under MRM mode,the average within-run CV of the results obtained on 3 serum samples was 0.95% (ranged from 0.92% to 0.99%) and the total CVwas 0.86% (0.82% to 0.89%),and under SIR mode,the within-run CV was 0.64% (from 0.54% to 0.77%) and the total CVwas O.69% (0.62% to 0.81%),respectively. Results on certified reference materials (SRM 1951 a Level Ⅰ and Level Ⅱ;GBW 09145 and GBW 09147) showed an average bias of 0.23% (0.14% to 1.00%) under MRM mode,and 0.24% (0.07% to 1.27%) under SIR mode.Conclusions An ID-LC/MS/MS method for serum cholesterol has been developed.It is specific and precise and may be used as a candidate reference method.