Diamond Thin Film Electrodes Research Articles

Electroanalysis of lincomycin using boron-doped diamond thin film electrode applied to flow injection system

The electroanalysis of lincomycin was investigated using boron-doped diamond thin film (BDD) electrodes. First, the electrochemistry of lincomycin was studied by cyclic voltammetry as a function of pH of the solution, scan rate and the concentration of lincomycin. Comparison experiments were carried out using glassy carbon electrode. Boron-doped diamond thin film electrode provided well-resolved oxidation irreversible cyclic voltammogram. It was found that the peak position was 1.2 V (versus Ag/AgCl reference electrode). Second, the amperometric detection with BDD electrode was coupled with the flow injection analysis for the determination of lincomycin. The linear range of 0.5–125 μM and the detection limit of 0.02 μM were obtained. The percent recovery was shown in a range of 96–103. This purposed method was also applied to a drug formulation sample. It was found that the results (293 mg mL −1) were comparable to those labeled (300 mg mL −1).

Preparation of boron-doped semiconducting diamond films using BF 3 and the electrochemical behavior of the semiconducting diamond electrodes

Boron-doped semiconducting diamond films were prepared using BF 3 by microwave plasma assisted chemical vapor deposition. B-doping was confirmed by SIMS and Raman spectroscopic measurements and the B-doping levels were estimated. Electrochemical behaviors of boron-doped diamond thin-film electrodes prepared using B 2H 6 and BF 3 were studied by measuring cyclic voltammograms for anodic oxidation of 1,4-difluorobenzene in the liquid electrolyte, neat Et 4NF·4HF. The results of the direct thermal interaction of elemental fluorine with hydrogenated and oxidized diamond surfaces are also presented.

A flow injection method for the analysis of tetracycline antibiotics in pharmaceutical formulations using electrochemical detection at anodized boron-doped diamond thin film electrode

A method using flow injection (FI) with amperometric detection at anodized boron-doped diamond (BDD) thin films has been developed and applied for the determination of tetracycline antibiotics (tetracycline, chlortetracycline, oxytetracycline and doxycycline). The electrochemical oxidation of the tetracycline antibiotics was studied at various carbon electrodes including glassy carbon (GC), as-deposited BDD and anodized BDD electrodes using cyclic voltammetry. The anodized BDD electrode exhibited well-defined irreversible cyclic voltammograms for the oxidation of tetracycline antibiotics with the highest current signals compared to the as-deposited BDD and glassy carbon electrodes. Low detection limit of 10 nM (signal-to-noise ratio = 3) was achieved for each drug when using flow injection analysis with amperometric detection at anodized BDD electrodes. Linear calibrations were obtained from 0.1 to 50 mM for tetracycline and 0.5–50 mM for chlortetracycline, oxytetracycline and doxycycline. The proposed method has been successfully applied to determine the tetracycline antibiotics in some drug formulations. The results obtained in percent found (99.50–103.01%) were comparable to dose labeled.

Effect of sp2-Bonded Nondiamond Carbon Impurity on the Response of Boron-Doped Polycrystalline Diamond Thin-Film Electrodes

The physical and electrochemical properties of boron-doped polycrystalline diamond thin-film electrodes, prepared with varying levels of -bonded nondiamond carbon impurity, were systematically investigated. This impurity was introduced through adjustment of the methane-to-hydrogen (C/H) source gas ratio used for the deposition. Volumetric gas ratios of 0.3, 0.5, 1, 2, 3, and 5% were employed. Proportional increases in the fraction of grain boundary, the extent of secondary nucleation, and the -bonded carbon impurity content resulted in increasing C/H ratio. Variations in the morphology and microstructure were monitored using atomic force microscopy (AFM) and Raman spectroscopy, respectively. The electrode response was assessed using and 4-tert-butylcatechol (4-tBC). All were 1 mM in concentration and dissolved in either 1 M KCl or 0.1 M While increased -bonded carbon content had little effect on the cyclic voltammetric peak separation and peak current for the first two redox systems, the impurity had a significant impact on the latter two, as decreased proportionally with increased -bonded carbon content. The effect of the impurity on the reduction of oxygen in 0.1 M and 0.1 M NaOH was also investigated. A direct correlation was found between the relative amount of the impurity, as estimated from Raman spectroscopy, and the overpotential for oxygen reduction. The greater the nondiamond content, the lower the kinetic overpotential for the reduction reaction. Tafel plots yielded an apparent exchange current density that increased and a transfer coefficient that decreased with the increased nondiamond carbon content. The results demonstrate that the grain boundaries, and the carbon impurity presumably residing there, can have a significant impact on the electrode reaction kinetics for certain redox systems and little influence for others. © 2004 The Electrochemical Society. All rights reserved.

Metal ion analysis in contaminated water samples using anodic stripping voltammetry and a nanocrystalline diamond thin-film electrode

Boron-doped nanocrystalline diamond thin-film electrodes were employed for the detection and quantification of Ag (I), Cu (II), Pb (II), Cd (II), and Zn (II) in several contaminated water samples using anodic stripping voltammetric (ASV). Diamond is an alternate electrode that possesses many of the same attributes as Hg and, therefore, appears to be a viable material for this electroanalytical measurement. The nanocrystalline form has been found to perform slightly better than the more conventional microcrystalline form of diamond in this application. Differential pulse voltammetry (DPASV) was used to detect these metal ions in lake water, well water, tap water, wastewater treatment sludge, and soil. The electrochemical results were compared with data from inductively coupled plasma mass spectrometric (ICP-MS) and or atomic absorption spectrometric (AAS) measurements of the same samples. Diamond is shown to function well in this electroanalytical application, providing a wide linear dynamic range, a low limit of quantitation, excellent response precision, and good response accuracy. For the analysis of Pb (II), bare diamond provided a response nearly identical to that obtained with a Hg-coated glassy carbon electrode.

Electrochemical Treatment of Simulated Copper CMP Wastewater Using Boron Doped Diamond Thin Film Electrodes—A Feasibility Study

The overall goal of this research was to develop a single treatment process that will economically treat wastewater generated during chemical-mechanical planarization (CMP) processing of integrated circuits. Present treatment technologies require multiple steps, are expensive, and generate secondary waste streams requiring further treatment or disposal. This research investigated the feasibility of electrochemical treatment of CMP wastewater using boron doped diamond (BDD) film electrodes. BDD electrodes were selected for their absence of catalytic activity for water electrolysis and their high stability under anodic polarization. Cyclic voltammetry and constant potential batch deposition experiments were performed to study removal of Cu/sup 2+/ ions at BDD cathodes. Galvanostatic oxidation experiments were performed to study removal of citrate and benzotriazole from aqueous solutions. For all conditions tested, Cu/sup 2+/ removal was mass transfer limited. Average Faradaic current efficiencies for removing Cu/sup 2+/ from solutions with initial concentrations between 15 and 50 mg/L ranged from 43% to 87%. The oxidation experiments showed that citrate could be completely oxidized to CO/sub 2/ and that its rate of oxidation was independent of the current density under the conditions tested. In contrast, rates of benzotriazole oxidation were proportional to the current density. Based on the results, a novel, flow-through electrochemical reactor capable of simultaneously removing metal ions and organic additives in a single pass has been proposed.

Flow-injection determination of iodide ion in nuclear emergency tablets, using boron-doped diamond thin film electrode

The electrochemical determination of iodide was studied at boron-doped diamond thin film electrodes (BDD) using cyclic voltammetry (CV) and flow-injection (FI) analysis, with amperometric detection. Cyclic voltammetry of iodide was conducted in a phosphate buffer pH 5. Experiments were performed using glassy carbon (GC) electrode as a comparison. Well-defined oxidation waves of the quasi-reversible cyclic voltammograms were observed at both electrodes. Voltammetric signal-to-background ratios (S/B) were comparable. However, the GC electrode gives much greater in the background current as usual. The potential sweep rate dependence exhibited that the peak current of iodide oxidation at 1 mM varied linearly ( r 2 = 0.998) with the square root of the scan rate, from 0.01 to 0.30 V s −1. This result indicates that the reaction is a diffusion-controlled process with negligible adsorption on BDD surface, at this iodide concentration. Results of the flow-injection analysis show a highly reproducible amperometric response. The linear working range was observed up to 200 μM ( r 2 = 0.999). The detection limit, as low as 0.01 μM (3 σ of blank), was obtained. This method was successfully applied for quantification of iodide contents in nuclear emergency tablets.

Electrochemical Treatment of 4-Nitrophenol-Containing Aqueous Wastes Using Boron-Doped Diamond Anodes

The electrochemical oxidation of aqueous wastes containing 4-nitrophenol (4-NP) using a boron-doped diamond thin-film electrode has been studied. Within the parameter ranges used (150−4000 mg of 4-NP dm-3, pH 2−12, 30−60 mA cm-2, 25−60 °C), the complete treatment of the organic waste was achieved. The maximum current efficiencies were obtained under kinetic control. On the basis of the results of voltammetric and galvanostatic electrolysis studies, a simple mechanistic model was proposed. The first stage in the treatment of 4-NP-containing aqueous wastes is the release of the nitro group from the aromatic ring. As a consequence, phenol or quinones are formed. These organic compounds are oxidized first to carboxylic acids (maleic and oxalic) and later to carbon dioxide. On the cathode, the reduction of the 4-NP to 4-aminophenol takes place. In alkaline media, this compound can be polymerized and transformed into a dark brown solid.

Continuous glucose monitoring using enzyme-immobilized platinized diamond microfiber electrodes

A sensitive and stable glucose biosensor for in vivo monitoring has been developed using boron-doped diamond microfiber (BDDMF) electrodes. The electrodes were modified with platinum nano-particles to detect H 2O 2, which was enzymatically produced by glucose oxidase (GOx) immobilized on the electrode surface. The platinum-modified BDDMF (Pt-BDDMF) electrodes exhibited much higher sensitivity compared to Pt-microfiber electrodes, Pt electrodes and Pt-modified diamond thin film electrodes. Deposition conditions for Pt nano-particles on the BDDMF electrodes and immobilization of GOx were optimized. GOx/overoxidized polypyrrole (OPPy)/Pt-modified BDDMF electrodes were applied for continuous interference-free glucose monitoring. Amperometric measurements of glucose showed a linear response in the range of 1–70 mM, with an R.S.D. of 3.7% for five injections of 100 μM glucose. The electrodes exhibited good stability over 3 months with no detected anodic current for ascorbic acid (AA), which is an interfering compound.

Electrochemical Incineration of Organic Pollutants on Boron-Doped Diamond Electrode. Evidence for Direct Electrochemical Oxidation Pathway

The electrochemical incineration of organic pollutants on a boron-doped diamond (BDD) thin film electrode was examined by bulk electrolysis, and the mechanism of oxidation was investigated. A compa...

Detection of Ascorbic Acid in an Ethanol–Water Mixed Solution on a Conductive Diamond Electrode

Abstract Conductive boron-doped diamond thin-film electrodes have been shown to be highly suitable as electrochemical detectors in flow injection analysis (FIA) due to the lack of electrode deactivation due to fouling and the ability to withstand highly positive electrochemical potentials. In the present work, a diamond electrode was applied to the detection of ascorbic acid (AA) in an alcohol–water mixed solution. During FIA of AA in an ethanol (EtOH)–water solution including 0.1 M NaClO4, the interference from EtOH oxidation that would have been observed with a Pt electrode was avoided, and the amperometric response for AA was observed with the use of a conductive diamond as the electrode material. Moreover, The detection limit for AA that could be observed was lower than that for a glassy carbon electrode, because diamond exhibits a lower background current, smaller background noise, and smaller injection noise. These findings suggest that the diamond electrode may be applied in the detection of other redox-active impurities and added substances in alcohol or alcohol–water solutions, such as chlorophyll, nicotinamide, caffeine, riboflavin, and dl-α-tocopherol.

Gradient liquid chromatography of leucine-enkephalin peptide and its metabolites with electrochemical detection using highly boron-doped diamond electrode

Boron-doped diamond thin film (BDD) electrodes have been used to study the oxidation reactions and to detect leucine-enkephalinamide (LEA) and its metabolites, tyrosine (T), tyrosyl-alanine (TA), tyrosyl-alanine-glycine (TAG) and leucine-enkephalin (LE) using cyclic voltammetry (CV), flow-injection analysis (FIA), and gradient liquid chromatography (LC) with amperometric detection. At diamond electrodes, well-defined and highly reproducible cyclic voltammograms were obtained with signal-to-background ( S/ B) ratios 5–10 times higher than those observed for glassy carbon (GC) electrodes. The analytical peaks of LC for LEA and its metabolites were well resolved. No deactivation of BDD electrodes was found after several experiments with standard as well as plasma samples, indicating high stability of the electrode. Calibration curves were linear over a wide range from 0.06 to 30 μ M with regression coefficients of 0.999 for all compounds. The limits of detection obtained based on a signal-to-noise ratio of 3:1 were 3, 2.2, 2.7, 20 and 11 n M for T, TA, TAG, LE and LEA, respectively. These values were at least one order lower than those obtained at GC electrodes, which has given limits of detection of 22.88, 20.64, 89.57, 116.04 and 75.67 for T, TA, TAG, LE and LEA, respectively. Application of this method to real samples was demonstrated and validated using rabbit serum samples. This work shows the promising use of conducting diamond as an amperometric detector in gradient LC, especially for the analysis of enkephalinamide and its metabolites.

Electron Transfer Kinetics of Ferrocene at Microcrystalline Boron‐Doped Diamond Electrodes: Effect of Solvent and Electrolyte

AbstractCyclic voltammetric measurements were made using well‐characterized microcrystalline boron‐doped diamond thin‐film electrodes to test the material's responsiveness for ferrocene as a function of scan rate, solvent, and electrolyte composition. Apparent heterogeneous electron transfer rate constants, k°app, of 0.042±0.015, 0.048±0.015, and 0.008±0.002 cm/s were observed in 0.1 M NaClO4/CH3CN, 0.1 M TBAClO4/CH3CN, and 0.1M TBAClO4/CH2Cl2, respectively. These rate constants, obtained using electrodes without any type of pretreatment, are similar to those observed for freshly polished glassy carbon. The results demonstrate that boron‐doped diamond is a viable material for the electrochemical analysis of nonaqueous analytes.

Electrochemical determination of captopril at boron-doped diamond thin film electrode applied to a flow injection system

A boron-doped diamond thin film (BDD) electrode was first used to study the electroanalysis of captopril in phosphate buffer (pH=9) by several techniques such as cyclic voltammetry, hydrodynamic voltammetry and flow injection with amperometric detection. Cyclic voltammetry was used to study the reaction as a function of concentration of analyte. The results were compared with a glassy carbon (GC) electrode at the same condition. Captopril undergoes irreversible reaction at both electrodes. However, the BDD electrode provided highly reproducible, well-resolved cyclic voltammogram and higher signal-to-background (S/B) ratio comparing with GC electrode. Linear range from 50 μM to 3 mM and detection limit of 25 μM (S/B≈3) were obtained from the BDD electrode using cyclic voltammetry. The potential sweep rate dependence of captopril oxidation (peak currents for 1 mM captopril linearly proportional to v 1/2, within the range of 0.01 to 0.3 V s −1) indicates that the oxidation current is diffusion controlled with negligible adsorption on the BDD surface. The flow injection experiments of the BDD electrode at the concentration from 0.5 to 100 μM provided a linear dynamic range and very low detection limit of 10 nM were obtained (S/N≈3). In addition, the determination of captopril in the commercial available tablets by flow injection system with amperometric detection at diamond electrodes has also been investigated. The results show very good precision (1.21–2.15%).

Electrochemical Oxidation of Aqueous Carboxylic Acid Wastes Using Diamond Thin-Film Electrodes

The electrochemical oxidation of three carboxylic acids (formic, oxalic, and maleic) using diamond thin-film electrodes was studied using voltametric and galvanostatic electrolysis techniques. The voltametric study shows an anodic current peak that indicates the existence of a direct oxidation reaction at the electrode surface. Galvanostatic electrolysis studies confirm the existence of mediated oxidation reactions and indicate almost total mineralization of the waste with a virtually direct transformation of carboxylic acids into carbon dioxide (no intermediates were detected) regardless of the current intensity, initial organic acid concentration, temperature, and supporting media. Experimental results obtained in the galvanostatic electrolysis study can be fitted satisfactorily (CV < 10%) using a simple model that considers both kinetic and mass-transfer processes.

Electrogeneration of Hydroxyl Radicals on Boron-Doped Diamond Electrodes

The electrogeneration of hydroxyl radicals was studied at a synthetic boron-doped diamond (BDD) thin film electrode. Spin trapping was used for detection of hydroxyl radicals with 5,5-dimethyl-1-pyrroline-N-oxide and with salicylic acid using electron spin resonance and liquid chromatography measurements, respectively. The production of hydrogen peroxide and competitive oxidation of formic and oxalic acids were also investigated using bulk electrolysis. The results have shown that oxidation of salicylic acid leads to the production of hydroxylated products (2,3- and 2,5-dihydroxybenzoic acids). These results demonstrate that the oxidation process on BDD electrodes involves hydroxyl radicals as electrogenerated intermediates. © 2003 The Electrochemical Society. All rights reserved.

Characterization and Electrochemical Responsiveness of Boron-Doped Nanocrystalline Diamond Thin-Film Electrodes

The deposition, characterization, and electrochemical responsiveness of boron-doped nanocrystalline diamond thin-film electrodes is reported. The films consist of clusters of diamond grains, ∼50−100 nm in diameter, and possess an rms surface roughness of 34 nm over a 5 × 5 μm2 area. The individual and randomly ordered diamond grains are approximately 10−15 nm in diameter, as evidenced by TEM. The ∼4-μm-thick films were deposited by microwave-assisted chemical vapor deposition (CVD) using a CH4/H2/Ar source gas mixture (1%/5%/95%). Under these conditions, C2, rather than CH3•, appears to be the dominant nucleation and growth precursor. The nanocrystallinity is a result of a growth and nucleation mechanism discovered by Gruen, which involves the insertion of C2 carbon dimer into C−H bonds on the growth surface (MRS Bull. 1998, 23, 32). The nanocrystalline morphology results from a high renucleation rate. However, unlike previously reported nanocrystalline diamond thin films that have electrical properties dominated by the high fraction of π-bonded carbon atoms in the grain boundaries, the present films are doped with boron, either using B2H6 or a solid-state boron diffusion source, and the electrical properties appear to be dominated by the charge carriers in the diamond. The films were characterized by scanning-electron microscopy, atomic-force microscopy, transmission-electron microscopy, visible-Raman spectroscopy, X-ray diffraction, boron-nuclear-reaction analysis, and cyclic voltammetry, using Fe(CN)63-/4-, Ru(NH3)63+/2+, IrCl62-/3-, methyl viologen, Fe3+/2+, and 4-tert-butylcatechol. Analytical application of this advanced carbon electrode material for the detection of trace metal ions is discussed.

Electrochemical analysis of d-penicillamine using a boron-doped diamond thin film electrode applied to flow injection system

The electroanalysis of d-penicillamine in 0.1 phosphate buffer (pH 7) was studied at a boron-doped diamond thin film (BDD) electrode using cyclic voltammetry as a function of concentration of analyte and pH of analyte solution. Comparison experiments were performing using a glassy carbon (GC) electrode. The BDD electrode exhibited a well-resolved and irreversible oxidation voltammogram, but the GC electrode provided only an ill-defined response. The BDD electrode provided a linear dynamic range from 0.5 to 10 mM and a detection limit of 25 μM (S/B≥3) in voltammetric measurement. It was also found that the peak potentials were decreased when the pH of the analyte solution was increased. In addition, penicillamine has been studied by hydrodynamic voltammetry and flow injection analysis with amperometric detection using the BDD electrode. The flow injection analysis results at the diamond electrode indicated a linear dynamic range from 0.5 to 50 μM and a detection limit of 10 nM (S/N≈4). The proposed method was applied to determine d-penicillamine in dosage form (capsules), the results obtained in the recovery study (255±2.50 mg per tablet) were comparable to those labeled (250 mg per tablet).

Electrochemistry of the aqueous europium(III)/europium(II) redox couple at conductive diamond electrodes

In the present paper, the electrochemical behavior of the Eu(III)/Eu(II) redox couple has been investigated at conductive diamond thin film electrodes. Measurements have been carried out by means of cyclic voltammetry, quasi-steady polarization curves (low-overpotential approximation) and ac impedance. The experimental picture indicates that the kinetics of electron transfer are more complex than that suggested by a classical outer-sphere mechanism.

Direct electrochemistry of cytochrome C at nanocrystalline boron-doped diamond.

Direct electron transfer of horse heart cytochrome c is measured at a nanocrystalline boron-doped diamond thin-film electrode. A quasi-reversible, diffusion-controlled cyclic voltammetric response is observed for untreated diamond. The peak currents change linearly with the concentration, and importantly, there is no electrode fouling. The results, observed for a hydrogen-terminated and uncharged surface, (i.e., no ionizable carbon-oxygen functional groups), raise interesting questions about the necessary surface interactions of cytochrome c for relatively rapid electrode kinetics.