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This paper describes the electrochemical behavior of five β-blockers at the polarized liquid–liquid interface formed between aqueous solution (sodium chloride solution or Britton–Robinson buffers) and bis(triphenylphosphoranylidene)ammonium tetrakis(4-chlorophenyl)borate (BTPPATPBCl) dissolved in 1,2-dichloroethane (the organic phase). All measurements reported in this work were conducted using cyclic voltammetry (CV). The effects of the concentration of analytes, the pH of the aqueous phase, and applied electrochemical parameters on the analytical performance of the studied system are studied and discussed. The linear dynamic ranges (LDRs) of the studied β-blockers were in the range of 5–200 μmol L−1 and the lowest limit of detection (LOD) value was determined for pindolol (LOD = 1.96 μM μmol L−1). The highest LOD value was 4.96 μmol L−1 found for nebivolol. In addition, physicochemical parameters such as the formal Galvani potential difference (Δ aqorg φ), formal Gibbs free energies of the ion transfer reaction (Δ aqorg G′) and partition coefficients (log P′aq/org) for all studied molecules were determined. The latter were compared and correlated with the available literature values of log Poctanol. Finally, a standard addition method was used to determine the concentration of nebivolol in pharmaceutical preparations using a platform based on the electrified liquid–liquid interface. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of cefotaxime (CTX+) was investigated at the polarized macro- and micro-interface between two immiscible electrolyte solutions (ITIES) by cyclic voltammetry and alternating current voltammetry. Miniaturization was achieved with fused silica microcapillary tubing entrapped in a polymeric casing. Scanning electron microscopy (SEM) was employed for the fabricated LLI support characterization. Voltammetric investigation of CTX+ at macro- and μ-ITIES allowed the determination of many physicochemical parameters, such as formal Galvani potential of the ion transfer reaction ( Δ org aq Φ ′ ), diffusion coefficients (D), formal free Gibbs energy of the ion transfer reaction (∆G′aq → org), and water-1,2-dichloroethane partition coefficient ( log P w a t e r / D C E C T X + ). Additionally, based on the results obtained the analytical parameters including voltammetric sensitivity, limits of detection and the limits of quantification (in micromolar range) were calculated. The applicability of the developed procedures was verified in spiked still mineral and tap water samples. [ABSTRACT FROM AUTHOR]

• Majority of cocaine cutting agents are inactive at the ITIES. • Molecular partitioning is followed using cyclic voltammetry. • Ion partition diagrams are plotted for interfacially active cutting agents. • The signal from amine based drugs is governed by their hydrophobicity. In this work, we have used cyclic voltammetry to investigate the interfacial behavior of cocaine cutting agents at the electrified liquid-liquid interface formed between a solution of the water and 1,2-dichloroethane phases. Among 27 chemical species used to adulterate cocaine street samples, only 8 were detectable in the available potential window. These include procaine, lidocaine, levamisole, hydroxyzine, caffeine, phenylethylamine, diltiazem, and diphenhydramine. From the calibration curves obtained using voltammetric data, we have extracted the electroanalytical parameters such as detection sensitivities, limits of detection, and limits of quantifications. Also, for each electrochemically active drug, we have calculated diffusion coefficients and plotted the ion partition and concentration fraction diagrams. All this information is discussed in a view of the cocaine sensors development focused on its detection from demanding matrix defined by the street samples composition. [Display omitted] [ABSTRACT FROM AUTHOR]