Comprehensive analysis of mandarin essential oils: Simultaneous qualitative, quantitative, chiral, and isotopic profiling via enantio-selective multidimensional gas chromatography coupled to isotopic ratio mass spectrometry

The current study aimed to provide a comprehensive analytical profile of the volatile fraction of sixty-three genuine mandarin essential oil (EO) samples, by exploiting a single instrument. For this purpose, a novel analytical approach was implemented, based on a heart-cut enantio‑selective multidimensional gas chromatographic system coupled in parallel to an isotopic ratio mass spectrometer and a single quadrupole mass spectrometer (Es-MDGC[sbnd]C-IRMS/qMS). For the first time, the stand-by analysis in the first dimension, usually employed to transfer target compounds to the second dimension, was here utilized to perform quali-quantitative analyses. Furthermore, the second dimension, equipped with a chiral stationary phase and coupled to a qMS and an IRMS, allowed the simultaneous evaluation of selected target components' chiral and carbon isotopic ratios. To the best of the Authors' knowledge, this research reports for the first time the δ¹³C values of specific enantiomers in mandarin EOs. The data gathered from Es-MDGC[sbnd]C-IRMS/qMS analyses revealed clear seasonal and geographical trends, while chemometric investigation confirmed the validity of the results obtained. This method allowed us to overcome the limitations associated with a monodimensional GC approach, while substantially reducing total analysis time, energy use, solvent consumption, and waste production, making it a powerful tool for authenticity assessment.