This study presents the synthesis of a novel asymmetric 1,3-di(alkoxy)imidazolium based room temperature ionic liquid, more precisely 1-butoxy-3-ethoxy-2-ethyl-imidazolium bis(trifluoromethane)sulfonimide, and its application as an extraction solvent in liquid-phase microextraction of cannabidiol from natural cosmetics. Quantification was implemented, using a high performance liquid chromatography system coupled to ultraviolet detection. Molecular structure elucidation was performed by nuclear magnetic resonance spectroscopy. The extraction procedure was optimized by means of two different design of experiments. Additionally, a full validation was executed. The established calibration model, ranging from 0.6 to 6.0 mg g⁻¹, was linear with a coefficient of determination of 0.9993. Accuracy and precision were demonstrated on four consecutive days with a bias within −2.6 to 2.3% and a maximum relative standard deviation value of 2.5%. Recoveries, tested for low and high concentration within the calibration range, were 80%. Stability of extracted cannabidiol was proven for three days at room temperature and fourteen days at 4 °C and −20 °C. An autosampler stability for 24 h was validated. Liquid-phase microextraction of cannabidiol from different formulated cream based cosmetics was performed, including four ointments and four creams. The results show that a significantly higher selectivity could be achieved compared to a conventional extraction methods with methanol.

Crosslinkers are indispensable constituents for the preparation of SPE materials with ethylene glycol dimethacrylate (EGDMA) and divinylbenzene (DVB) among the most prominent representatives. A crosslinker that has not yet been used for the preparation of SPE sorbents is 3,3’-(hexane-1,6-diyl)bis(1-vinylimidazolium) bromide [C₆-bis-VIM] [Br]. In this study, we synthesized differently crosslinked vinylimidazole polymers with EGDMA, DVB and [C₆-bis-VIM] [Br] and evaluated their extraction efficiencies towards phenolic acids. Dispersive SPE experiments performed with the [C₆-bis-VIM] [Br] crosslinked polymers exhibited significantly higher extraction recoveries for the majority of analytes. Due to these promising results, the [C₆-bis-VIM] [Br] crosslinked polymer was optimized in terms of the monomer to crosslinker ratio and an efficient dispersive SPE protocol was developed, with maximum recoveries ranging from 84.1–92.5% and RSD values ˂ 1%. The developed extraction procedure was also applied to cartridges resulting in recoveries between 97.2 and 98.5%, which were on average 5% higher than with the commercial anion exchange sorbent Oasis^® MAX. Furthermore, the sorbent was regenerated showing a good reusability for the majority of analytes. In conclusion, this study clearly highlights the yet untapped potential of the crosslinker, [C₆-bis-VIM] [Br], with respect to the synthesis of efficient anion exchange polymers for SPE.

This study reports the synthesis of the room temperature ionic liquid 1-propyloxy-3-ethoxyimidazolium bis(trifluoromethane)sulfonamide for the extraction of bergapten and bergamottin from hydroalcoholic cosmetic samples by means of dispersive liquid–liquid microextraction. Molecular structures of the final ionic liquid as well as intermediate products were confirmed by nuclear magnetic resonance spectroscopy. Analyses were performed with high performance liquid chromatography with subsequent diode array and fluorescence detection. The extraction procedure was optimized with the design of the experiment using a three level Box–Behnken approach. Applying the synthesized room temperature ionic liquid as extraction medium, the optimized workflow demonstrated high recoveries illustrating powerful isolation properties for furanocoumarins, which are comparable or even better than using typical extraction solvents. Moreover, the workflow was validated regarding instrumental limits, linearity, accuracy, repeatability and stability of analytes according to international guidelines. To test its applicability on a more complex matrix, hydroalcoholic cosmetic samples were analyzed. Despite highly complex matrices, accurate and precise quantification in the range of 0.04–1.25 μg mL⁻¹ was achieved in spiked and unspiked samples, with bias <10% and RSD < 12%.