Voltammetric quantification of an anesthetic drug propofol (2,6-diisopropylphenol) on boron-doped diamond electrode in the pharmaceutical formulations

In this paper, the detailed electrochemistry of propofol (PRO) which is one of the intravenous agents commonly used for sedative-hypnotic purposes was examined. In cyclic voltammetry, the agent showed one irreversible and diffusion?controlled oxidation peak, resulting in the formation of a couple with a reduction and re-oxidation wave at less positive potentials. The effect of electrode pretreatment procedures on the electrochemical response of PRO was investigated by using square wave voltammetry (SWV) and the optimum procedure was used to improve the signal response in subsequent studies. Quantification of PRO was done based on the first oxidation peak using SWV. After optimization of all variables, the linear working range of PRO was found to be between 2.5 ?g mL-1 (1.4?10-5 mol L-1) and 160.0 ?g mL-1 (1.1?10-3 mol L-1, n=15) with a detection limit 0.71 ?g mL-1 (3.9?10-6 mol L-1). No noteworthy interference effect was detected. Also, the developed method was used for quantification of PRO in pharmaceutical sample.

Bis(tetraphenylarsonium) hexafluoridotechnetate(IV) dihydrate: preparation, structure and spectroscopic analysis

Reports of quadrivalent transition-metal fluoride salts containing bulky organic cations are limited. In this context, we prepared the bis(tetraphenylarsonium) hexafluoridotechnetate(IV) dihydrate salt, (C24H20As)2[TcF6]·2H2O, by a cation metathesis reaction of (NH4)2[TcF6] in water. This is the first report of an arsonium salt of the hexafluoridotechnetate(IV) dianion. (AsPh4)2[TcF6]·2H2O crystallizes in the triclinic space group P\overline{1}. The [TcF6]2− anion adopts a slightly distorted octahedral geometry with an average Tc—F bond length of 1.933 Å. The cyclic voltammogram of (AsPh4)2[TcF6]·2H2O in CH3CN shows a one-electron reversible oxidation wave at 1.496 V.

Synthesis and properties of highly organosoluble aromatic polyimides containing N-(4-(di(1H-indole-3-yl)methyl)phenyl) moieties

A new diamine monomer containing indole unit, 3,5-diamino- N-(4-(di(1H-indol-3-yl)methyl)phenyl)benzamide, was successfully synthesized and applied in the preparation of a series of polyimides (PIs) via a conventional two-step polymerization procedure with three aromatic tetracarboxylic dianhydrides. The prepared polymers showed excellent solubility in organic solvents such as N-methyl-2-pyrrolidinone (NMP), N, N-dimethylacetamide, and N, N-dimethylformamide. Flexible and strong films of PIs were obtained via casting from their solutions. The glass transition temperature of these polymers was in the range of 223–264°C. They were fairly stable up to a temperature around 300°C and lost 10% weight at 372°C in nitrogen atmosphere. All of the polymers revealed absorption maxima around 323 nm with a fluorescence emission maxima around 378–406 nm in NMP. The cyclic voltammetry of the PIs exhibited an oxidation wave with a peak at 1.07 V. The resulting polymer films had tensile strengths from 83 MPa to 107 MPa, elongates at break of 7–10%, and tensile moduli of 2.2–2.3 GPa.

Electrochemical oxidation of salicylhydroxamic acid on Pt electrode

The electrochemical oxidation behavior of salicylhydroxamic acid (SHAM) on a Pt electrode was investigated in aqueous solution of different pHs, containing 10 mM of SHAM, at 25°C, by cyclic voltammetry technique. The results indicate that the SHAM was oxidized more easily in alkaline medium than acidic and neutral mediums, and the oxidation peaks of SHAM shifted toward lower potential values by increasing pH values. The SHAM electrooxidation involves an irreversible transfer of one or two electron, depending on the pH of solution. If solution pH is lower than 3 and higher than 7, the two electron transfer is involved in the electrooxidation. While, from pH=3 to pH=7, the SHAM electrooxidation involves an irreversible transfer of one electron and two protons in the first step, in agreement with the one step one-electron mechanism. The effect of SHAM concentration on the electrode reaction was investigated in artificial saliva solution. SHAM gives a single irreversible oxidation wave over the wide concentration range studied. Possible mechanism of SHAM electrooxidation was proposed.

Electrocatalytic Oxidation of Oxalic Acid Using a Multielectrolytic Modified Glassy Carbon Electrodes

Electrocatalytic oxidation activity of oxalic acid can be observed by using a multielectrolytic modified glassy carbon electrode (MMGCE). The MMGCE was fabricated by using the following electrolytic-oxidation/reduction processes. First, the functional groups containing nitrogen atoms such as amino group are introduced by the electrode oxidation of a bare glassy carbon electrode in an ammonium carbamate aqueous solution, and next, this electrode was electroreduced in sulfuric acid, and it was found that the reduction current gradually increased as the electrolysis time increased. This suggests that functional groups containing nitrogen atoms contributing the catalytic electron transfer of hydrogen ion are introduced. To observe the electrode oxidation wave of oxalic acid, the voltammmetric measurements of oxalic acid was carried out by using MMGCE in an acidic medium. The oxidation wave of oxalic acid at low potential range was appeared in the linear sweep voltammograms. The MMGCE exhibited well-defined peak of oxalic acid oxidation in acidic medium.

Synthesis and characterization of bis(ferrocenylcarboxylato)telluranes

A convenient route to the synthesis of the first bis(ferrocenyl carboxylato) telluranes has been developed. Reactions of 1,1,2,3,4,5,6-heptahydro-1,1-(dihydroxo)tellurane and 1,1,2,3,4,5-hexahydro-1,1-(dihydroxo)tellurophene with ferrocene carboxylic acid give 1,1,2,3,4,5,6-heptahydro-1,1-bis(ferrocenyl carboxylato)tellurane (3) and 1,1,2,3,4,5,-hexahydro-1,1-bis(ferrocenyl carboxylato)tellurophene (5), respectively. The X-ray structure of 3 shows that it contains a tellurium heterocycle (C5H10Te), present in a chair conformation, sandwiched between two ferrocene units with carboxylate groups acting as spacers. Compound 3 also exhibits modest second harmonic generation (SHG) efficiency. The electrochemical studies of 3 and 5 through cyclic voltammetry show only one oxidation wave, indicating the presence of independent redox centers leading to reversible single-step two-electron redox systems.Key words: tellurane, ferrocenylcarboxylate, SHG efficiency, electrochemistry.

EXCITABLE CHEMICAL MEDIUM CONTROLLER FOR A ROBOTIC HAND: CLOSED-LOOP EXPERIMENTS

We discuss the experimental implementation of a chemical controller for a robotic hand. In the present case study, we have designed a closed system where a Belousov–Zhabotinsky (BZ) thin layer chemical reactor was linked to the robotic hand via an array of photo-sensors and the fingers of the hand were able to stimulate the excitation dynamics in the BZ medium via the local addition of an activator species. A principal working loop of the chemo-robotic system is that oxidation wave fronts traveling in the medium are detected by photo-sensors and cause (via a microcontroller) the fingers of the hand to bend. When a finger bends, it is set up to apply a small quantity of colloid silver to the reaction and thus causes an additional excitation wave. The traveling and interacting waves stimulate further movements of the fingers and patterns of behavior are observed. These patterns of behavior have been modeled using a cellular automaton. In the paper, we offer an experimental set-up, including algorithms and interfacing, for an experimental chemical robotic hand controller, which contributes to the fields of nonclassical computation, nonlinear physics, and unconventional robotics.