Rapid screening and quantification of glucocorticoids in essential oils using direct analysis in real time mass spectrometry

Rationale There is a strong demand to develop a method capable of rapid screening for the adulteration of glucocorticoids (GCs) in cosmetics. An ambient ion source– direct analysis in real time (DART), coupled with quadrupole time of flight mass spectrometry (QTOF MS) was used for the rapid screening of GCs in essential oils. Methods Liquid–liquid extraction was employed prior to the DART-QTOF MS analysis. Calibration curves for eight GCs were obtained using methyltestosterone as an internal standard. MS/MS experiments and accurate mass measurements were carried out to provide reliable and powerful evidence for the adulteration of targeted GCs. Results Quantification results were obtained in terms of linearity (R2 for all GCs, 0.986–0.996), sensitivity (limit of detection, 2.0–50 ng/mL), and repeatability (RSD, 1.2–6.0%). The entire analytical process can be finished in 5 min, compared with the GC/MS or LC/MS methods for which typical analysis times range from tens of minutes to >1 h. In addition, comparison of the performance of DART and ESI ion sources showed that DART possessed a relatively low matrix effect when handling complex samples. Conclusions A new method for the rapid screening and quantification of GCs in essential oils was developed using DART-QTOF MS. Copyright © 2016 John Wiley & Sons, Ltd.