Cu(HBTC)(4,4′-bipy)·3DMF nanorods supported on platinum electrode as an electrochemical sensing platform for efficient vitamin B ₁₂ detection

Monitoring of vitamin B ₁₂ is important in the quality control of various pharmaceutical products. In this work, we design an ultrasensitive electrochemical sensor for the detection of vitamin B ₁₂ employing Pt modified Cu(HBTC)(4,4′-bipy)·3DMF (Pt = Platinum; DMF = N,N′-dimethylformamide; 4,4′-bipy = 4,4′-bipyridine; HBTC = 1,3,5-benzenetricarboxylic acid) electrode as an efficient electrocatalyst. The copper (Cu) complex nanorods were synthesised by solvothermal method and characterised by different surface analytical techniques. Cyclic voltammetric analysis reveals that the modified electrode shows excellent electrocatalytic redox reversibility towards Co ³⁺ /Co ²⁺ redox couple at −0.192 and -0.268 V (vs. Ag/AgCl) with a sensitivity of 0.104 µA µM ⁻¹ , a low detection limit of 50 nM, a signal-to-noise ratio of 3 and a wide linear range of 0.1–188.2 µM. The novelty of the system is that both oxidation and reduction currents Co ³⁺ /Co ²⁺ redox couple has been used for the calibration curve so that the analytical errors during the course of analysis would be minimised. The enhanced electrocatalytic ability of the material has enabled discrimination of vitamin B ₁₂ from potential interfering species. The fabricated electrode was applied for the detection of vitamin B ₁₂ in two commercial pharmaceutical tablets and the results were found to be satisfactory.