First Voltammetric Procedure for Sensing Synthetic Thyroid Hormone Liothyronine Sodium in Tablet Dosage Form Using Anionic Surfactant Media at a Boron-Doped Diamond Electrode

Abstract

In this study, the voltammetric sensing of liothyronine sodium (LT3Na) was assessed using a boron-doped diamond (BDD) electrode, which had undergone electrochemical pretreatment to improve its surface activity. Cyclic voltammograms of LT3Na revealed well-defined, single, irreversible behavior that is governed by a dual mechanism of adsorption and diffusion at around +1.16 V (vs. Ag/AgCl) in 0.1 mol L- 1 H2SO4 solution. The oxidation peaks of LT3Na were studied using various electrolyte solutions, including Britton-Robinson buffer (0.04 mol L- 1, pH 2-10), phosphate buffer (0.1 mol L- 1, pH 2.5 and 7.4), acetate buffer (0.1 mol L- 1, pH 4.7), and 0.1 mol L- 1 solutions of HNO3, H2SO4, and HClO4, by square wave adsorption stripping voltammetry. The results showed that the oxidation peaks of LT3Na were pH-dependent across the range of 5.0 to 9.0; however, the optimal peak was observed in the H2SO4 solution. Introducing a sodium dodecyl sulfate (anionic surfactant, SDS) into the working electrolyte enhanced the anodic peak currents of LT3Na. A linear correlation for the quantification of LT3Na was obtained at +1.05 V in a 0.1 mol L- 1 H2SO4 solution containing 4 x 10-4 mol L- 1 SDS, under optimized conditions (vs. Ag/AgCl) (using open-circuit condition in 30 s accumulation step). The linear range spanned from 0.5 to 30.0 mu g mL-1 (7.4 x 10- 7-4.5 x 10-5 mol L- 1), with a detection limit of 0.15 mu g mL-1 (2.2 x 10-7mol L- 1). The LT3Na concentration in the drug formulation was successfully quantized using this method. According to our knowledge, this is the initial study to present an electrochemical analysis of this compound.