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Voltammetric sensors with laterally placed working electrode are an interesting alternative to classic electrodes since they offer enhanced performance in electroanalysis. Their characteristics include easier preparation for measurement, removal of interferences and gas bubbles, amplification of mass-transport, and possibility of miniaturization and automation. In this review, construction and characteristics of the custom-designed in our team cyclically renewable, silver, gold, bismuth, glassy carbon, ceramic and amalgam annular band, bi-band, ring, and multidisc electrodes are discussed in detail. They represent the current trends in electroanalysis, aimed at reducing of amount of the used toxic electrode materials, like mercury and its compounds, and organic solvents used for a sample preparation, and are coherent with the concept of Green Chemistry. For each sensor type available strategies for mechanical and electrochemical surface renovation/activation before measurement are elucidated and evaluated on the basis of interpretation of voltammetric and tensammetric curves. Particular attention is put on electrochemical characteristics of the described sensors and their application for determination of trace amounts of metal ions and their complexes, organic compounds, and surface-active substances by means of tensammetry, and anodic, cathodic, adsorptive and catalytic adsorptive stripping voltammetry. Final considerations are addressed to the possibility of measurement automation and related future prospects.

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This paper presents a new type of the working electrode -bi-Disc Glassy Carbon Electrode (b-DGCE). An innovative design of the electrode surface consists of two glassy carbon discs (φ = 1.0 mm) symmetrically placed on the lateral surface of the guidewire formed with chemically resistant resin. The results obtained during characterization of the electrode, conducted by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), were consistent with the reversible reaction theory. The b-DGCE was constructed and used as a working electrode for determination of vitamin K2 (VK2) by the differential pulse adsorptive stripping voltammetry (DP AdSV). The electrochemical behavior of VK2 on the b-DGCE was investigated. Parameters affecting the stripping performance, such as composition and concentration of the supporting electrolyte as well as several key instrumental parameters were investigated and optimized. Under the optimized experimental conditions, a linear voltammetric response was received for VK2 in the concentration range from 0.06 to 0.55 mg•L −1 with limit of detection (LoD) of 0.017 for cathodic and 0.021 mg•L −1 for anodic scans, for a short accumulation time of 10 s. Repeatability of the method, expressed as RSD (n = 5) was 2.12 and 1.37 mg•L −1 for cathodic and anodic scans, respectively.

In this paper, the fabrication, surface characterisation and electrochemical properties of graphite flake (GFPE) and multilayer graphene (MLGPE) paste electrodes are described. The Raman investigations and scanning electron microscopy were used to analyze and compare structure of both carbon materials. The electroanalytical performance of both electrodes was examined and compared on the basis of the square-wave and cyclic voltammetric behavior of acetaminophen and model redox systems. Results of those studies revealed that GFPE has a larger electroactive surface area and better conductive properties, whilst MLGPE demonstrate better analytical characteristic in case of acetaminophen (AC) determination. AC determination was developed using square wave voltammetry (SWV) and square wave stripping voltammetry (SWSV). For both working electrodes, the process of accumulation enabled us to obtain an extended linear range and to lower the detection limit. In pharmaceutical formulations, AC was determined with good recovery.Sensors 2020, 20, 1684 2 of 15 anisotropic thermal conductivity, with high conductivity in the horizontal direction and low thermal conductivity in the vertical direction [20]. Graphite flakes have found application in electrochemistry as, for instance, a promising anode material for lithium ion batteries [21]. GFs have unique features, including excellent strength and high fracture toughness [22]. Furthermore, the layered graphite structure and weak forces between the layers lead to the possibility of easily refreshing the surface of a paste electrode made of graphite flakes. These properties make graphite flake a promising electrode material [23].Recently, graphene is considered the material of the "rising star" and has received attention due to its unique properties. This form of carbon is considered as a prototype of two-dimensional carbon system and all other dimensionalities [5,24,25]. Graphene can be wrapped into fullerenes (0D), rolled into carbon nanotubes (1D), or used to create graphite (3D) [24]. The development of knowledge related to graphene led to the creation of graphene-based materials. Multilayer graphene (MLG) is a 2D nanomaterial composed of stacked monolayers of graphene. Importantly, both MLG and GNP (graphene nanoplatelets) are composed of graphene layers arranged on top of each other. However, they differ in the number of layers and properties. The number of graphene layers in GNP is greater than 10, while that in MLG varies from 11 to 21 [26]. Experiments show that for model redox systems there is no strong correlation between the flake thickness and the electron transfer rate [27]. However, a higher electron transfer was achieved for flakes consisting of less than 20 graphene layers [27]. The properties of MLG are more similar to those of graphene than to those of graphite [26], and thus make MLG a promising material for the fabrication of carbon paste electrodes.Acetaminophen (AC) is very commonly used in many diseases and pain treatment. Because of its antipyretic and analge...