Development of a sensitive and simple method for the analysis of upadacitinib in biological samples using two different electrodes

Abstract

This study explains the electrochemical application using a glassy carbon electrode (GCE) and boron-doped diamond electrode (BDDE) to determine upadacitinib (UPA), which is a selective inhibitor of Janus kinase 1 (JAK1) protein from the standard solution and serum sample. Electrochemical oxidation behavior was evaluated regarding pH and scan rate effect, and the oxidation mechanism was found to be a mixture of adsorption/diffusion for BDDE and diffusion-controlled for GCE. The possible oxidation mechanism was explained in detail using indole, zolmitriptan, ruxolitinib, and tofacitinib. UPA was determined using GCE and BDDE in pH 4.7 acetate buffer solution (ABS). The linear concentration range was 8.0 x 10-7 - 6.0 x 10-5 M for GCE and 4.0 x 10-6 - 6.0 x 10-5 M for BDDE in standard solution. The obtained limit of detection (LOD) values are 1.91 x 10-8 M and 3.69 x 10-8 M for GCE and BDDE, respectively. Furthermore, the feasibility and accuracy of both electrodes were demonstrated through commercial human serum sample application and recovery studies, and the recovery% value was between 100.76% and 102.96%. For the precision evaluation, the repeatability and reproducibility values for GCE were 0.96-1.36 (standard solution-serum) and 1.48-1.99 (standard solution-serum); for BDDE were 0.42-0.85 (standard solution-serum) and 1.13-1.37 (standard solution-serum), respectively. Compared to the literature, this study stands out as an easier, environmentally friendly, affordable, and sensitive electrochemical option for UPA determination using GCE and BDDE.