Enantiomeric separation of nefopam and cathinone derivatives using a supramolecular deep eutectic solvent as a chiral selector in capillary electrophoresis

The present study investigates the utilization of a supramolecular deep eutectic solvent (SUPRADES), consisting of sulfated-β-cyclodextrin (S-β-CD) and citric acid (CA), as a chiral selector (CS) in capillary electrophoresis for the enantiomeric separation of nefopam (NEF) and five cathinone derivatives (3-methylmethcathinone [3-MMC], 4-methylmethcathinone [4-MMC], 3,4-dimethylmethcathinone [3,4-DMMC], 4-methylethcathinone [4-MEC], and 3,4-methylendioxycathinone [MDMC]). A significant improvement in enantiomeric separation of the target analytes was observed upon the addition of S-β-CD-CA to the background electrolyte (BGE), leading to a baseline separation of all analytes. In particular, the optimum percentage of S-β-CD-CA, added to the BGE, was determined to be 0.075% v/v for NEF (R_s = 1.5) and 0.050% v/v for three out of five cathinone derivatives (R_s = 1.5, 1.6, and 2.4 for 3-MMC, 4-MEC, and 3,4-DMMC, respectively). In the case of 4-MMC and MDMC, a higher percentage of the CS, equal to 0.075% and 0.10% v/v, respectively, was required to achieve baseline separation (R_s = 1.5, 1.9 for MDMC and 4-MMC, respectively). The outcomes of the present study highlight the potential effectiveness of using SUPRADES as a CS in electrophoretic enantioseparations.