A Chiral Ni(II) Complex Immobilized on Carboblack C as a Readily Available and Effective Enantioselective Voltammetric Sensor for Recognition of Atenolol Enantiomers in Real Samples

The search of a chiral selector is an essential aspect in the development of enantioselective voltammetric sensors, as stereoselectivity is achieved through the chiral surface of the electrode. This paper introduces the first application of a readily accessible and robust chiral Belokon’s Ni(II) complex as an efficient chiral selector. This complex, derived from a Schiff base of glycine and (S)-2-(N-benzylprolyl)aminobenzophenone, is immobilized onto a graphitized Carboblack C paste electrode, enabling efficient recognition and determination of atenolol (Atn) enantiomers. The characteristics of the developed electrochemical analytical sensor were evaluated, revealing an effective electrode surface area (A) of 7.51±0.53 mm² and a charge transfer resistance (R_et) of 11.50±0.09 kΩ. A linear relationship was established between the Atn oxidation peak current and its concentration in solution, maintained across a range of 100 to 1000 µM. The detection limits for (S)-Atn were found to be 2.76 (LOD) and 9.23 µM for the lower limit of detectable concentrations (LOQ), while for (R)-Atn, these values were 4.51 and 15 µM, respectively. Notably, the sensor exhibited greater sensitivity to (S)-Atn, with a potential difference (ΔE_p) of 20 mV and a current ratio (i_S/i_R) of 1.60. The developed paste electrode demonstrates the ability to selectively recognize Atn enantiomers in model solutions, biological fluids, and pharmaceutical samples. Furthermore, employing principal component analysis (PCA) and independent class analogy modeling methods, the study presents a potential approach for identifying pharmaceutical formulations of Atn by their manufacturers.