Chiral separation of propranolol by electrokinetic chromatography using nanodiamonds and human serum albumin as a pseudo-stationary phase in river water

Propranolol is currently considered as an emerging contaminant in water bodies. In this study, R- and S-propranolol were determined in river samples by electrokinetic chromatography (EKC) using nanodiamonds (NDs) and human serum albumin (HSA) as a pseudo-stationary phase in order to achieve enantioseparation. Previously, river samples were preconcentrated using a column filled with Amberlite® IR-120 and Dowex® 50WX8 resins. The setting up of influential factors such as temperature, voltage, pH, and HSA and NDs concentration is accurately described along this manuscript. A multivariate study and optimization was carried out to obtain the enantioseparation of propranolol (Rs = 2.91), which was reached under the following experimental conditions: voltage of 16 kV, temperature of 16°C, phosphate buffer pH 9.5, NDs of 0.20%, and HSA of 15 μmol l⁻¹. The recoveries of analytes under optimal conditions were higher than 98%. The limits of detection were 0.85 μg l⁻¹ for R- and S-propranolol. The method was applied to real samples, and the obtained results in three different water sources studied were 1.02, 0.59, and 0.30 μg l⁻¹ for the R-enantiomer and 0.99, 0.54, and 0.28 μg l⁻¹ for the S-enantiomer. The accuracy of the proposed methodology (including bias and precision) has allowed us to propose it as a successful tool for the control of water quality.