The design of an indicator carbon-paste electrode of ergonomic design and testing of an electrode for voltammetric determination of a number of substances of inorganic and organic origin is described. The electrode is made of a graphite rod with a diameter of 6 mm and a length of 70 mm, covered with insulation and having a cavity filled with an electroactive carbon-containing material at the end of the rod. The characteristic features of the proposed electrode - the insulating shell of the housing made of shrink tubing and the electrolytic coating of the cavity surface with a conductive metal film - make it possible to simplify the design of the electrode and increase mechanical strength, extend the service life of the electrode, and also provide the possibility of volumetric and surface modifications with economical consumption of modifying reagents.

The working and metrological characteristics of the new carbon-paste indicator electrode were evaluated when testing food products, beverages, natural objects for the content of heavy metal ions and pharmaceuticals for the content of hydrogen peroxide and riboflavin (vitamin B₂), ascorbic acid (vitamin C) using various options: cyclic and inversion voltammetry with linear sweep, rectangular and differential pulses.

When using the developed electrode modified with a bismuth film to determine cadmium and lead ions, the linear dynamic range of the calibration characteristic was 10-110 and 10-160 micrograms/dm³, respectively. The linear dynamic range of the calibration characteristic for the determination of riboflavin was 0.01 - 0.2 mmol/L (3.76 - 75.3 mg/L) for a volumetrically modified nano/microparticles of manganese dioxide electrode. The same electrode, modified with MnO₂ nanoparticles obtained by reducing Mn(VII) ions with Mn(II) ions in a neutral medium, was used for chronoamperometric determination of hydrogen peroxide in model and pharmaceutical preparations with a detection limit of 0.03 mmol/L for H₂O₂.

The simplicity of manufacturing the developed carbon-paste indicator electrode, high performance and cost-effectiveness when using expensive and scarce modifiers allow us to recommend it for use in voltammetric analysis and the creation of various biosensor systems.

In the present work, we performed the optimization of electrografting of adrenaline onto a glassy carbon electrode surface. The cyclic voltammetry technique was used to immobilize the compound on the electrode surface by immersing it in an acidic adrenaline solution. This grafting was achieved by conducting 20 successive CV scans over a wide potential range. The stability of the obtained layer was analyzed using the SWV technique. The conducted research shows that it is possible to create a stable adrenaline layer on the GCE surface using voltammetric techniques. Additionally, once a stable layer was immobilized, its sensitivity to certain metal cations—which cannot be directly detected electrochemically—was verified. After exposing the sensor to designated cationic solutions, there was a significant decrease in the adrenaline signal. This suggests potential future applications in cation determination.