Abstract:

Objective To establish isotope-dilution liquid-chromatography tandem-mass spectrometry（ID-LC-MS/MS） for determining serum cortisone,and to evaluate its performance. Methods ABSCIEX TRIPLE QUAD 5500 liquid-chromatography tandem-mass spectrometry was used to determine serum cortisone quantitatively. According to the Clinical and Laboratory Standards Institute（CLSI） document,the performance,including linearity,precision,extraction and recycling rates and accuracy,was verified. Results Cortisone-d4 was added to analytes, and they were equilibrated at room temperature for 1 h. ID-LC-MS/MS for determining serum cortisone had linear regression equation Y=0.018 7X+0.043 4 （r=0.999 8）. The linear range was 25-500 ng/mL. The determination limit was 0.05 ng/mL for serum cortisone. The within-run and between-run coefficients of variation（CV） were <4% and <6%. The extraction and recycling rates were 84.5%-90.4%. The biases of the International Federation of Clinical Chemistry and Laboratory Medicine External Quality Assessment Scheme for Reference Laboratories in Laboratory Medicine（RELA）-A and RELA-B were 3.19% and 2.84%. Conclusions The established ID-LC-MS/MS has good precision,accuracy and repeatability,which is suitable for determining serum cortisone.

Key words: Isotope-dilution liquid-chromatography tandem-mass spectrometry, Performance verification, Cortisone