Comparison of evaporation techniques for the preparation of salivary cortisol for analysis by liquid chromatography–electrospray tandem mass spectrometry

Objective Compare evaporation techniques in the work-up procedure of saliva samples for cortisol analysis by a previously validated liquid chromatography–tandem mass spectrometry (LC–MS/MS) method. Design and methods Samples were evaporated using freeze drying, centrifugal concentration, and nitrogen flow and analyzed by LC–MS/MS. Results Cortisol concentrations detected using each technique did not significantly differ. Factors other than the recovery of cortisol were evaluated. Conclusions Evaporation using freeze drying/centrifugal concentration is an automated process, reducing overall processing time for analysis of numerous samples.