## 3 Results and Discussion  
### Adrenaline Transfer Across Aqueous/DCE Interface in Simple Matrices  
The ITIES technique has proven to be a valuable electrochemical approach for detecting non-redox active molecules. It works by facilitating the transfer of ions (with a \(Z^{+}\) charge) across two immiscible phases: in this case, an aqueous solution and DCE. The transfer of ions between these phases (described in Equation (1)) is driven by the Gibbs free energy, which can be supplied in the form of a voltage using a potentiostat. By reversing the applied potential, ions are returned across the interface, creating an ion-transfer cycle that can be visualized as a cyclic voltammogram (CV). These CVs offer crucial information,with the half-wave potential (E\({}_{1/2}\))--the potential at which half of the maximum current occurs--serving as a fingerprint to distinguish different analytes. \[\mathrm{I}_{(\mathrm{aq})}^{\mathrm{z+}}\rightleftharpoons\mathrm{I}_{(\mathrm{org })}^{\mathrm{z+}} \tag{1}\]  
\[\mathrm{I}_{(\mathrm{aq})}^{\mathrm{z+}}+\mathrm{L}_{(\mathrm{org})} \rightleftharpoons[\mathrm{I}-\mathrm{L}]_{(\mathrm{org})}^{\mathrm{z+}} \tag{2}\]  
In cases where the energy required for transfer is high, it can be reduced by introducing a suitable ionophore, L, which facilitates the transfer process by interacting selectively with specific ions (Equation (2)). These facilitated ion transfers produce characteristic CVs and steady-state currents at micro- or nano-ITIES, which are often formed at the tips of nanopipets, and the steady-state current (i\({}_{\mathrm{d}}\)) can be described using the relationship shown in Equation (3). In this equation, z represents the charge of the analyte; C is its concentration; D is the diffusion coefficient in the originating phase; r is the pipet tip radius; x accounts for the thickness of the pipet's glass wall [25]; and F is the Faraday constant. \[\mathrm{i}_{\mathrm{d}}=4\mathrm{xzFDCr} \tag{3}\]  
In this study, the ionophore DB24C8 was chosen to facilitate the transfer of Adr across the aqueous/DCE interface, using a glass-nanopipet electrode. The selection of DB24C8 was based on its proposed ability to form a stable complex with Adr [22], which enhances ion transfer efficiency and improves the sensitivity of the electrochemical response. Unlike previously reported electrodes for Adr detection [31; 32; 33; 34], the fabrication of these glass nanopipets offers several advantages. The process is not only straightforward and rapid but also cost-effective, making it an attractive alternative to more complex or expensive electrode fabrication methods. Furthermore, these nanopipet electrodes are highly versatile and can be tailored for specific applications, making them ideal for the development of portable yet robust electrochemical sensors. The simplicity of the fabrication process, combined with their high performance, paves the way for the deployment of these sensors in field-based or point-of-care settings, where cost and ease of use are critical. This approach represents a significant advancement in the development of practical, real-time detection systems for Adr and potentially other analytes in various environments. Initially, the experiments were conducted in a simple matrix of 3 M KCl before moving on to more complex matrices. At an Adr concentration of 100 uM, steady-state current and CV data were collected at two distinct E\({}_{1/2}\) values in KCl. Increasing the concentration of Adr allowed us to explore the impact of concentration changes on the steady-state current. However, unlike previous studies and the predictions based on Equation (3) [25; 35], we observed no corresponding increase in steady-state current with higher Adr concentrations (Figure 1). Instead, CVs exhibited a shift toward more positive potentials as the Adr concentration increased, while the shape of Adr CVs closely resembled that of the background signal.