Packed-Nanofiber Solid-Phase Extraction Column for Determination of Cortisol in Hair Samples

In recent years, many studies found that hair cortisol can serve as a good biomarker of chronic stress. A high-performance liquid chromatography-Fluorescence (HPLC-Flu) method for the determination of hair cortisol based on novel packed nanofiber solid-phase extraction (PFSPE) was established. The incubation solution of hair samples was extracted by the new type of PFSPE column. The column was eluted with 100 μL of ethanol, and then 230 μL of concentrated sulfuric acid was added into the eluant and retained for 2 min. The mixture of reactants and water was secondly extracted by the PFSPE column, in which the target compounds were desorbed with 50 μL of methanol directly. The detection limit of cortisol was 0.5 ng g −1 (signal-to-noise ratio of 3). The within-run and between-day precisions (RSD) were below 6.8% and 8.9%, and the average recovery of cortisol spiked into the hair samples was 88.9%. The method of pretreatment is simple, fast and green. Moreover, the established method can be used to determine the level of cortisol in hair samples, which is a simple, inexpensive determination method for applications in physiology, psychiatry, sports medicine, cognitive science, psychology and other areas of research.