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 (R-2 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 (C) 2016 John Wiley & Sons, Ltd.