A novel method for analysing key corticosteroids in polar bear (Ursus maritimus) hair using liquid chromatography tandem mass spectrometry

• We developed a novel LC–MS method for analysing key corticosteroids in polar bear hair.
• i-PLE and ic-PLE were used to extract steroids from polar bear hair.
• C18 SPE was used to clean-up steroids following PLE extraction.
• Absolute method recoveries for the corticosteroids were in the range 60–81%.
• The concentration range for corticosteroids in polar bear hair was 0.13–0.32 ng/g.

This paper presents the development and evaluation of a methodology for extraction, clean-up and analysis of three key corticosteroids (aldosterone, cortisol and corticosterone) in polar bear hair. Such a methodology can be used to monitor stress biomarkers in polar bears and may provide as a useful tool for long-term and retrospective information. We developed a combined pressurized liquid extraction (PLE)–solid phase extraction (SPE) procedure for corticosteroid extraction and clean-up followed by high pressure liquid chromatography tandem mass spectrometry (HPLC–MS/MS) analysis. This procedure allows for the simultaneous determination of multiple steroids, which is in contrast to previous polar bear studies based on ELISA techniques. Absolute method recoveries were 81%, 75% and 60% for cortisol, corticosterone and aldosterone, respectively. We applied the developed method on a hair sample pooled from four East Greenland polar bears. Herein cortisol and corticosterone were successfully determined in levels of 0.32 ± 0.02 ng/g hair and 0.13 ± 0.02 ng/g hair, respectively. Aldosterone was below limit of detection (LOD < 0.17 ng/g). The cortisol hair concentration found in these East Greenland polar bears was consistent with cortisol levels previously determined in the Southern Hudson Bay and James Bay in Canada using ELISA kits.