pinecone/core-2020-05-10-deduplication huggingface dataset:
Electrochemical behaviour of carbamazepine in acetonitrile and dimethylformamide using glassy carbon electrodes and microelectrodes

The electrochemical reduction of carbamazepine in acetonitrile (ACN) and dimethylformamide (DMF) using a glassy carbon electrode and microelectrodes has been studied. The reduction process is consistent with an Electrochemical-Chemical mechanism (EC) involving a two electron transfer followed by a first order reaction, as shown by the cyclic voltammetry and differential pulse voltammetry. Half-wave potential, number of electron transfer, diffusion coefficient and rate constant of the associated chemical reaction are reported. Detection limits are in DPV: LoD=0.92 and 0.76 μg mL-1 in ACN and DMF, respectively. Precision (%RSD) and recovery (%) values when pharmaceutical compounds (200mg carbamazepine tablets) and spiked plasma samples were tested ranged from 1.09 to 9.04% and % recoveries ranged from 96 to 104.1%
Reducing antioxidant capacity evaluated by means of a controlled potential oxidative attack

An analytical method suitable for an antioxidant sensor is presented following the response of these substances to an extensive oxidative attack imposed by electrochemical means. The electrochemical assay simulates the action  of a reactive oxygen species (ROS) by means of electrolyses carried out at a potential which is settled at the formal potential of the ROS.
The antioxidant activities of trolox and ascorbic, gallic and caffeic acids and of mixtures these antioxidants was estimated from  the charge required for the complete oxidation of the antioxidants from assays where the oxidative attack by O2 and by O2 were simulated.Fundação para a Ciência e Tecnologia (FCT)Centro de Química da Universidade do Minh
Quantification of tin and lead in binary alloys using voltammetry of immobilized microparticles

Voltammetry of immobilized microparticles (VMP) has been used in this work for the quantitative determination of tin and lead particles in their binary alloys. Carbon paste electrodes, which contained small amounts of tin and lead or their mixtures, were used as working electrodes and square wave voltammograms of each electrode were recorded. Quantification was performed using optimum experimental conditions, obtained by an experimental design technique. The calibration was made by measuring the percentage peak height of each metal taking the sum of peak currents of the both metals as 100%. The results were compared with quantitative results of X-ray fluorescence (XRF) technique to evaluate the capability of VMP method in its quantitative determination of solid samples
Revisiting the Response Mechanism of Polymeric Membrane Based Heparin Electrodes

Potentiometric membrane electrodes that respond to heparin and other polyanions were introduced in the early 1990s. Herein, the mechanism of polymer membrane electrode type heparin sensors is revisited. The extraction/diffusion of heparin is studied via both potentiometric and impedance spectroscopic techniques using a prefractionated heparin preparation that contains polyanionic species >10 000 Daltons. The reversal in  EMF  response using this heparin preparation indicates diffusion of higher MW heparin fragments to the backside of the membrane. Diffusion coefficients are calculated using a novel formula derived from the phase boundary potential model and Fick′s second law of diffusion. Impedance spectroscopy is also employed to show that high MW heparin species are extracted and diffuse across the PVC membranes
Permeability of Human Tooth Surfaces Studied In Vitro by Electrochemical Impedance Spectroscopy

Electrochemical Faradaic impedance spectroscopy was applied to evaluate dependence of the electrical resistance on human teeth. The experiments were performed using iodide anions as a redox probe to model permeability of teeth for fluoride upon an iontophoresis process. Tooth molars were used - as these are teeth most affected by tooth decay processes in vivo. Teeth compared included sound molars - with no evidence of pit and fissure decay, teeth with pits and fissures regarded 'clinically' as showing signs of decay, and teeth with crowns removed to present exposed dentin surfaces. A difference of more than an order of magnitude in electrical resistance was observed between sound molars and those regarded as showing evidence of tooth decay processes. Sound dentin, as expected from structural considerations demonstrated significantly lower resistance when compared to sound molars. Importantly, the difference in tooth resistance measured between carious and sound molars was shown to be much more representative of their structural integrity than comparison of digitally processed images of the teeth. The results support the utility of electrochemical Faradaic impedance spectroscopy for the development of understanding on how tooth electrical resistance may vary according to structural changes. This understanding may be useful to continued refinements in the use of electrical resistance measures as caries diagnostics and support generically the potential for iontophoretic processes in in-office fluoride treatments of teeth. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.This research was supported by Procter and Gamble Company in the frame of the project “Instigation of Charged Species Delivery in Oral Cavity via Iontophoresis”. The authors acknowledge the assistance and support of Mr. James Zoladz in selection and preparation of tooth specimens for analysis.Peer Reviewe
Selectivity Enhancement for Chloride Ion by In(III)‐Porphyrin‐Based Polymeric Membrane Electrode Operated in Pulsed Chronopotentiometric Mode

A robust selectivity enhancement of an In(III)‐porphyrin ionophore‐based chloride‐selective electrode under pulsed chronopotentiometric measurement mode that enables the detection of chloride ions in the presence of a normally interfering concentration of salicylate ions is described. This enhancement is achieved by the rapid depletion of the surface concentration of the more dilute lipophilic anion during an initial anodic current pulse period due to extraction of this preferred anion into the membrane phase. Measurement of chloride with a detection limit of 8 mM and near Nernstian response slope in the presence of 1 mM salicylate is possible using the pulstrode method
Multiplexed Ultrasensitive Determination of Adrenocorticotropin and Cortisol Hormones at a Dual Electrochemical Immunosensor

A novel dual electrochemical immunosensor for the multiplexed determination of adrenocorticotropin (ACTH) and cortisol is reported. Aminophenylboronic acid-modified dual screen-printed carbon electrodes were prepared on which the corresponding ACTH and cortisol antibodies were immobilized. Competitive immunoassays involved biotinylated ACTH and alkaline phosphatase labelled streptavidin, or alkaline phosphatase labelled cortisol. Differential pulse voltammetry upon 1-naphtyl phosphate addition was employed to monitor the affinity reactions. The ranges of linearity were 5.0×10−5−0.1 and 0.1−500 ng/mL for ACTH and cortisol. The usefulness of the dual immunosensor was demonstrated by analyzing certified human serum samples with good recoveries
Direct electrochemistry of Heme Proteins on Electrodes Modified with Didodecyldimethyl Ammonium Bromide and Carbon Black

A novel matrix based on commercially available carbon black (CB) N220 and didodecyldimethyl ammonium bromide (DDAB) was shown to be a reliable support for direct electron transfer reactions between screen printed electrode (SPE) and Fe(III)-heme proteins. Cytochrome c(cytc), myoglobin (Mb), horseradish peroxidase (HRP) and\ud
cytochromes P450 (CYP 51A1, CYP 3A4, CYP 2B4) generated well-shaped cyclic voltammograms on SPE/CB/\ud
DDAB electrodes (both in solution and in immobilized state). The attractive performance characteristics of CB\ud
modified electrodes are advantageous over single-walled carbon nanotubes (SW CNT) based ones. The achieved\ud
direct electrochemistry of heme proteins on CB/DDAB-modified electrodes provided successful elaboration of the\ud
immunosensor for cardiac Mb. The immunosensor showed applicability for diagnostics of myocardial infarction displaying significant difference in cardiac Mb content of human blood plasma samples taken from the corresponding\ud
patients
A novel approach to monitoring of the diffusion junction potential in speciation studies by polarography under very acidic conditions : Part I : The reversible cd(ii)-picolinic acid system

A new polarographic procedure has been developed for the study of metal-ligand equilibria at pH<2 by applying
an in situ monitoring of the diffusion junction potential by introducing a noncomplexing witness metal ion, Tl(I).
As a case study, this procedure was applied to the Cd(II)-picolinic acid (pyridine-2-carboxylic acid) system; DCTAST
polarography was employed at 25 8C and ionic strength of 0.25–0.5 M (H,Na)NO3. Log b values of 4.26 0.03,
7.86 0.11 and 10.47 0.12 were obtained for the ML, ML2 and ML3 complexes, respectively, and compare well to
literature values. The first log b (6.27 0.07) value for the MLH species was successfully determined, for which
a crystal structure has been reported recently.National Research Foundation (NRF) and the University of the Witwatersrandhttp://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1521-4109hb201
Electrochemical Magnetic Immunosensors for the Determination of Ceruloplasmin

Electrochemical immunosensors for ceruloplasmin (Cp) are reported for the first time. Two configurations involving magnetic beads (MBs) functionalized with Protein A or Streptavidin for immobilization of Cp antibodies were compared, using competitive immunoassay with synthesized alkaline phosphatase-Cp conjugate. Upon capturing MBs-immunoconjugates onto screen-printed carbon electrodes, quantification of Cp was accomplished by DPV measurement of 1-naphthol generated after 1-naphthylphosphate addition. Linear ranges of calibration curves and detection limits were 0.1–1000 µg/mL and 0.040 µg/mL (Protein A-MBs), and 0.025–20 µg/mL and 0.018 µg/mL (Strept-MBs). Good results were obtained in the determination of Cp in spiked human serum samples
Electrochemical detection of TNT at cobalt phthalocyanine mediated screen-printed electrodes and application to detection of airborne vapours

We describe the use of cobalt phthalocyanine as a mediator to improve the sensitivity for the electrochemical detection of TNT. Commercial screen-printed electrodes containing cobalt phthalocyanine were employed for determination of TNT. Improved sensitivities compared to screen-printed carbon electrodes without phthalocyanine were observed, current response for cyclic voltammetric measurements at modified electrodes being at least double that of unmodified electrodes. A synergistic effect between oxygen and TNT reduction was also observed. Correlation between TNT concentrations and sensor output was observed between 0–200 µM TNT. Initial proof-of-concept experiments combining electrochemical determinations, with the use of an air-sampling cyclone, are also reported
Study of Cobalt(III) Corrole as the Neutral Ionophore for Nitrite and Nitrate Detection via Polymeric Membrane Electrodes

Cobalt(III) 5,10,15‐tris(4‐ tert ‐butylphenyl) corrole was synthesized and incorporated into plasticized poly(vinyl chloride) membranes and studied as a neutral carrier ionophore via potentiometry. This cobalt(III) complex has binding affinity to nitrite, and the resulting membrane electrode yields reversible and Nernstian response toward nitrite. Enhanced nitrite selectivity is observed over other anions, including lipophilic anions such as thiocyanate and perchlorate when an appropriate amount of lipophilic cationic sites are added to the membrane phase. Detection limit to nitrite is ca. 5 µM. Using tributylphosphate as the plasticizer with the cobalt(III) corrole species yields electrodes with enhanced nitrate selectivity
Facilitated Transport of Ions and Glucose by Amphotericin B Across Lipid Bilayers in the Presence or Absence of Cholesterol

The transport of ions and glucose across bilayer lipid membranes (BLM) facilitated by amphotericin B (AmB) is studied by use of planar BLMs and liposomal membranes. The transport characteristics change with time in the presence of cholesterol, while it is independent of time in the absence of cholesterol. The carrier-type transport is observed immediately after the addition of AmB. In the presence of cholesterol, AmB forms a 1 : 1 complex with cholesterol and the channel is formed by aggregation of AmB-cholesterol complexes. It is concluded that the number of the channels increases with time and that the carrier-type transport decreases instead
Alzheimer disease biomarker detection through electrocatalytic water oxidation induced by iridium oxide nanoparticles

Iridium oxide nanoparticles (IrO NPs) synthesized following a previously reported chemical route are presented as novel tags for immunosensing taking advantage of their electrocatalytic activity towards water oxidation reaction (WOR). Cyclic voltammetry and chronoamperometry for the evaluation of the IrO NPs electrocatalytic activity towards WOR at neutral pH were used. The chronoamperometric current recorded at a fixed potential of +1.3V constituted the analytical signal allowing the quantification of IrO NPs at nM levels. Modification of the surface of citrate-capped IrO NPs with anti-Apolipoprotein E antibodies (αApoE) was successfully achieved and the as-prepared conjugates were used for the electrocatalytic detection of ApoE Alzheimer disease (AD) biomarker in a magnetosandwich immunoassay, reaching a detection limit of 68ng/mL. Human plasma of a patient suffering AD was also evaluated, estimating an ApoE concentration of 20μg/mL which is in concordance with the obtained in previously reported approaches. This novel IrO NPs based electrocatalytic assay presents the advantage of the signal generation in the same medium where the immunoassay takes place (PBS, pH7.4) avoiding the use of additional reagents which also opens the way to future integrated biosensing systems and platforms with interest for other proteins as well as DNA and cells analysis
Electrochemical detection of miRNAs

The recent progress made in the development of electrochemical methods for microRNA (miRNA) detection is\ud
presented. This progress is conceived to be largely due to the invention of novel assay methodologies and the use of various bioreagents and nanostructures. These enable a rigorous control over the sensing interface, provide enormous signal amplifications and single-base mismatch specificity. Femtomolar or even subfemtomolar detection limits were shown to be feasible by electrochemical assays. Thus electrochemical detection methodologies are of perspective for diagnostic miRNA detection
Cava wine authentication employing a voltammetric electronic tongue

The application of an Electronic Tongue for the classification of cava samples based on their different ageing times is reported. As such, voltammetric responses were obtained from an array of six bulk-modified graphite-epoxy electrodes, which exhibited marked mix-responses towards the different samples. Obtained responses were then preprocessed employing FFT and the resulting coefficients were input to a LDA model which allowed the classification of the samples according to its vintage time. Besides, a quantitative model employing ANNs was built for the prediction of the total amount of sugar present in the samples, a parameter also used to classify cava samples
Intrinsically porous polymer protects catalytic gold particles for enzymeless glucose oxidation

The enzymeless glucose oxidation process readily occurs on nano-gold electrocatalyst at pH7, but it is highly susceptible to poisoning (competitive binding), for example from protein or chloride. Is it shown here that gold nanoparticle catalyst can be protected against poisoning by a polymer of intrinsic microporosity (PIM-EA-TB with BET surface area 1027m2g-1). This PIM material when protonated, achieves a triple catalyst protection effect by (i) size selective repulsion of larger protein molecules (albumins) and (ii) membrane ion selection effects, and (iii) membrane ion activity effects. PIM materials allow "environmental control" to be introduced in electrocatalytic processes
Study of the Histamine Electrochemical Oxidation Catalyzed by Nickel Sulfate

Thin layer technique was applied to the indirect anodic oxidation of histamine, catalyzed by NiSO4. Coulometric determination of the electron number demonstrates that histamine complexes Ni(II) and resulting adducts can be electrochemically oxidized in a single‐electron reaction, to lead Ni(III)‐histamine. The system Ni(III)/Ni(II) acts as ‘redox mediator’ for histamine oxidation. The equilibrium constant of the Ni(II)‐histamine complex formation was 106 , value showing the strong affinity between species. High content of histamine (>0.1 M), detected in fresh fish (previously exposed to the sun) extracts, showing potentialities for future design of a sensor for direct measurement in fish
Influence of Charging Current and Potential Drop on the Propagation of the Change in the Membrane Potential

Propagation of a change in a potential difference between two aqueous phases (W1 and W2) across a membrane was examined by using three membrane cells (A, B and C). At first, the cell A was electrically connected with the cell B by controlling the ionic compositions. By changing the connection with the cell A from the cell B to the cell C indicating the different membrane potential, the change of the membrane potential was propagated. The delay and decrement of the propagation was observed by setting capacitors or resistors in the electric circuit
Chitosan/AuNPs Modified Graphene Electrochemical Sensor for Label-Free Human Chorionic Gonadotropin Detection

A new immunosensor is presented for human chorionic gonadotropin (hCG), made by electrodepositing chitosan/gold-nanoparticles over graphene screen-printed electrode (SPE). The antibody was covalently bound to CS via its Fc-terminal. The assembly was controlled by electrochemical Impedance Spectroscopy (EIS) and followed by Fourier Transformed Infrared (FTIR). The hCG-immunosensor displayed linear response against the logarithm-hCG concentration for 0.1–25 ng/mL with limit of detection of 0.016 ng/mL. High selectivity was observed in blank urine and successful detection of hCG was also achieved in spiked samples of real urine from pregnant woman. The immunosensor showed good detection capability, simplicity of fabrication, low-cost, high sensitivity and selectivity
Measuring the Electrode Kinetics of Surface Confined Electrode Reactions at a Constant Scan Rate

Abstract: The kinetics of surface confined electrode reactions\ud
of alizarin, vitamin B12, and vitamin K2 is measured\ud
with square-wave voltammetry over a wide pH interval,\ud
by applying the recent methodology for kinetic analysis\ud
at a constant scan rate [V. Mirceski, D. Guziejewski, K.\ud
Lisichkov, Electrochim. Acta 2013, 114, 667–673]. The reliability and the simplicity of the recent methodology is\ud
confirmed. The methodology requires analysis of the\ud
peak potential separation of the forward and backward\ud
component of the response as a function of the pulse\ud
height (SW amplitude), for a given frequency (i.e. constant\ud
scan rate) of the potential modulation
Use of a bioelectronic tongue for the monitoring of the photodegradation of phenolic compounds

The application of a voltammetric bioelectronic tongue for the simultaneous monitoring of catechol, m-cresol and guaiacol in wastewater is reported. Voltammetric responses obtained from an array of bulk modified (bio)sensors, containing enzymes such as tyrosinase and laccase, were combined with chemometric tools such as artificial neural networks (ANNs) for building the quantitative prediction model. To this end, the chemometric model was first built employing a factorial design, validated employing an external test set of samples (n=14; total NRMSE of 0.076), and afterwards applied to the monitoring of the mineralization of the three phenol pollutants during a photo-Fenton advanced oxidation process
A novel approach to monitoring of the diffusion junction potential in speciation studies by Polarography under very acidic conditions : Part II : The quasi-reversible Cu(II)-picolinic acid system

The use of polarography to accurately determine stability constants of complexes formed under very acidic conditions (below pH 2) is demonstrated. The diffusion junction potentials, which must be accounted for below pH 2, were evaluated by applying protocols developed where Tl(I) is used as an internal reference. The Cu(II)-picolinic acid (2-pyridinecarboxylic acid) system studied was chosen since the CuL+ species only exists in solution below pH 2 under the conditions used and literature data exists to confirm the accuracy of procedure. Additionally, the reduction of Cu(II) was quasi-reversible and procedures to determine the reversible half-wave potentials were investigated. Average log  values of 7.75  0.09 for CuL+ and 14.8  0.1 for CuL2 were obtained, which compared well to literature data.National Research Foundation (NRF). University of the Witwatersrand.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1521-41092016-02-28hb201
Simultaneous titration of ternary mixtures of Pb(II), Cd(II) and Cu(II) with potentiometric electronic tongue detection

An automatic titration method is reported to resolve ternary mixtures of transition metals (Pb²⁺,Cd²⁺ and Cu²⁺) employing electronic tongue detection and a reduced number of pre-defined additions of EDTA titrant. Sensors used were PVC membrane selective electrodes with generic response to heavy-metals, plus an artificial neural network response model. Detection limits obtained were ca. 1 mg L¯¹ for the three target ions and reproducibilities 3.0 % for Pb²⁺, 4.1 % for Cd²⁺ and 5.2 % for Cu²⁺. The system was applied to contaminated soil samples and high accuracy was obtained for the determination of Pb²⁺. In the determination  Cd²⁺ and Cu²⁺,sample matrix showed a significant effect
ITO-ITO Dual-Plate Microgap Electrodes: E and EC′ Generator-Collector Processes

Tin-doped indium oxide electrodes are fabricated and employed in a dual-plate microtrench geometry with the inter-electrode gap controlling the mass transport conditions in generator-collector mode. Electrodes are fabricated with 2–50 µm gap sizes and variable trench depths by controlling assembly parameters. Non-ideal behaviour is observed for three aqueous redox systems: Ru(bpy) equation image, 1,1′-ferrocenedimethanol and Ru(NH3). Under fast mass transport conditions, the former two systems exhibit slower oxidation features. For Ru(NH3), non-steady-state behaviour is observed due to irreversible (ECirrev′) consumption of oxygen in the microtrench. A mechanism leading to hydrogen peroxide formation via superoxide in Ru(NH3) solution is proposed. Under optimised conditions all three redox systems provide reliable trench depth calibration information