TLDR Methanol is better than isopropanol for washing grizzly bear hair to measure cortisol.
The study compared methanol and isopropanol as wash solvents for removing external cortisol contamination from the hair of 4 grizzly bears and 4 polar bears, aiming to preserve internal hair cortisol concentrations. Methanol was found to be more effective than isopropanol, particularly in grizzly bears, as isopropanol led to higher hair cortisol concentrations due to potential cross-reactivity with the ELISA antibody. In polar bears, no significant difference was observed between the solvents. The study also highlighted significant variability in cortisol quantification results from different ELISA kits, with the Oxford EA65 kit providing lower cortisol values. The findings suggested methanol was preferable for washing bear hair to avoid artefactual increases in hair cortisol concentration due to external contamination.
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