A validated LC–MS/MS method for simultaneous determination of key glucocorticoids in animal hair for applications in conservation biology

Materials and reagents

Ultrapure water was produced by a Milli-Q water purification system (Merck Millipore, Darmstadt, Germany). Hypergrade isopropanol, acetonitrile, formic acid, and acetic acid were from Merck (Darmstadt, Germany), and methanol was from POCH (Gliwice, Poland). Standards of cortisol, cortisone, corticosterone, and cortisol-D₄ were from Sigma-Aldrich (Saint Louis, Missouri, USA). Stock and working solutions of standards were prepared in methanol and stored at − 20 °C before use.

For SPE purification of hair extracts, the Strata-X cartridges (Polymeric Reversed Phase,…