Determination of Cortisol in Human Serum Using Ultrasonic Extraction Coupled With Isotope Dilution Liquid Chromatography–mass Spectrometry

Abstract

A simple method for the determination of total cortisol in serum was developed. The method used ultrasonic extraction coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), which provides high sensitivity, short pretreatment, simple experimental procedures, and low costs. In this method, cortisol in human serum was separated by ultrasound with acetonitrile as an extraction solvent and was analyzed by LC-MS/MS. Excellent precision was achieved with inter-day coefficients of variation (CVs) of 0.3-0.7% and intra-day CVs of 0.3-0.6%. The mean recovery of the assay was 100.5% with a range 99.6-101.0%. The accuracy of this method was confirmed using an international interlaboratory comparison sample (CCQM-K63a).