## 1 Introduction  
Stress is a complex and evolving concept that describes the interactions between organisms and environmental stimuli perceived as threats to survival or well-being [1]. The dynamics of stress responses vary depending on the type, intensity, duration, context, and pre-existing health conditions of the organism [2]. Research into stress and stress-related disorders indicates that the chemical mediators of the stress response have biphasic effects, potentially leading to pathophysiological imbalances with long-term implications for physical and mental health [2, 3, 4, 5, 6, 7]. Adrenaline (Adr), also known as epinephrine, is a key catecholamine and medullary hormone that acts as both a neurotransmitter and hormone modulator. It is secreted predominantly by chromaffin cells in the adrenal glands in response to acute stress, mediated by splanchnic nerves [1, 8]. This hormone triggers rapid responses in the body, including vasopressor activation of \(\alpha\)- and \(\beta\)-adrenergicreceptors, leading to increased respiration, blood pressure, and heart rate [5; 6; 7]. Abnormal and persistently elevated levels of Adr are associated with chronic diseases such as pheochromocytoma [9], diabetes, heart disease, obesity [10], compromised immunity [1], chronic depression [4], schizophrenia [11], attention deficit hyperactivity disorder [12], and neurodegenerative diseases [2; 13]. Traditional methods for determining and characterizing Adr levels involve the analysis of blood, plasma, urine, or cerebrospinal fluid samples using techniques like immunoassays [14], mass spectrometry [15], chromatography [16], fluorescence [17], and colorimetry [18]. While these methods are sensitive and offer low limits of detection, they often lack biological compatibility, require intensive sample pretreatment, and fail to provide real-time physiological information [19; 20]. Electrochemical sensors have emerged as a promising alternative, offering real-time, in situ characterization of biomolecules with excellent selectivity, sensitivity, portability, and reduced pretreatment requirements [20]. However, the voltammetric determination of Adr at solid electrode surfaces is challenging due to the presence of high concentrations of ascorbic acid in biological samples [21]. The versatility of the electrodes in the method of ion transfer across two immiscible electrolyte solutions (ITIES), capable of monitoring a wide range of reactions and analytes at the nanoscale, makes them particularly well-suited for such analyses. ITIES has gained attention as a unique electrochemical analysis method, sensitive to both redox-active and redox-inactive analytes such as catecholamines [22; 23; 24], metal ions [25], pharmaceuticals [26; 27], and complex molecules like proteins [28]. The introduction of chemical ionophores by [PERSON] and colleagues provided a solution to detecting chemicals with an ion-transfer potential beyond the conventional window, enabling selective targeting based on functional groups and expanding the scope of ITIES [29]. In 2013, [PERSON] and colleagues reported the transfer of dopamine and noradrenaline cations across a water/1,6-Dichlorohexane interface with the ionophore dibenzo-18-crown-6 ether (DB18C6); however, the transfer of Adr cations was not observed, likely due to the low affinity of the crown ether cavity for the sterically hindered secondary amine on the Adr side chain. The authors suggested that a larger crown ether ring, such as dibenzo-24-crown-8 ether DB24C8, could increase complexation affinity and facilitate Adr cation transfer [22]. Despite the potential of ITIES, there is a lack of extensive research on Adr cation transfer using this technique. In this study, we propose a new approach for characterizing ion transfer for Adr across the water/1,2-Dichloroethane (DCE) interface using both DB18C6 and a larger crown ether ring, DB24C8 ionophores, using glass nanopipets.