Online solid-phase extraction liquid chromatography–mass spectrometry of hair cortisol using a surrogate analyte

Longitudinal Monitoring of Hair Cortisol Using Liquid Chromatography–Mass Spectrometry to Prevent Hypercortisolism in Patients Undergoing Glucocorticoid Replacement Therapy

“…Our group has previously established a prediction interval for segmented HCC in a healthy population (1–20 pg/mg, with LOD and LOQ being 0.3 and 0.8 pg/mg, respectively, and accuracy and precision below 15%). 24 Even as the interval was obtained by measuring cortisol levels of students in a very narrow range of age, it showed several features that might apply to hypercortisolism or hypocortisolism monitoring.1. The interval is rather broad, analogous to the plasma and urinary cortisol; however, the values are unaffected by short-term hormonal fluctuations.2.…”

“…A group of 114 healthy volunteers, described elsewhere, was used as a reference interval for healthy individuals to compare hair cortisol values. 24 The Masaryk University Ethical Committee approved the study, and all participants provided written informed consent.…”

“…Online SPE LC-MS of HCC has been previously described. 24 Briefly, this method was developed using a Dionex Ultimate 3000RS (Waltham, MA) module, a trapping column (SPE column), an analytical column (2.1 × 100 mm, 2.7 μm C18 Ascentis; Phenomenex, Torrance, CA), and a 12-minute gradient program at a flow rate of 0.2 mL/min.…”

“…Online SPE LC-MS of HCC has been previously described. 24 Briefly, this method was developed using a Dionex Ultimate 3000RS (Waltham, MA) module, a trapping column (SPE column), an analytical column (2.1 • 100 mm, 2.7 mm C18 Ascentis; Phenomenex, Torrance, CA), and a 12minute gradient program at a flow rate of 0.2 mL/min. The outlet of the analytical column was connected to a Bruker EVOQ Qube triple quadrupole mass spectrometer (Bruker, Bremen, Germany) operated in the negative heatedelectrospray ionization mode with the following parameters: spray voltage, 23500 V; cone temperature, 3508C; cone gas flow, 20 psi; heated probe temperature, 3508C; probe gas flow, 40 psi (nitrogen); and nebulizer gas flow, 50 psi.…”

“…LC-MS with online solid-phase extraction (SPE) was used to assess HCC. 24 Because of the lack of reference materials, we used a surrogate analyte in an authentic hair matrix, first performed and validated by Binz et al 25 in 2016. Such an approach refused the treatment of the most distal segment of hair as a "blank" matrix, which is commonly used in other studies determining hair cortisol by LC-MS.…”