A quantification assay based on isotope dilution mass spectrometry to determine the concentration of progesterone in human serum was reported. Incorporated with (13)C3-progesterone, serum samples were subjected to progesterone extraction and clean-up by C4 solid-phase-extraction columns and hexane-based liquid/liquid extraction, respectively. The cleaned-up serum samples were then subjected to MALDI-TOF mass spectrometry for the quantification of progesterone. In the study, the recovered progesterone concentration determined by the assay showed good robustness and constancy in comparison to conventional radioimmunologic assay. We concluded that the (13)C3-progesterone-based quantification assay is a robust method for the measurement of serum progesterone. Advantages of this technique includes: * This study describes a MALDI-TOF/MS method for the determination of serum progesterone. * The technique is simple and easy to apply on MALDI-TOF/MS for serum progesterone analysis. * The correlation coefficient between MALDI-TOF MS and RIA was 0.981 for serum progesterone.
