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991.
Highly boron-doped diamond (BDD) electrode, have been examined for simultaneous detection of purine and pyrimidine bases in mild acidic media by using HPLC with amperometric detection. Cyclic voltammetry at as-deposited (AD) and anodically oxidized (AO) BDD were used to study the electrochemistry and to optimize the condition for HPLC applications. At AO BDD electrode, due to its higher overpotential of oxygen evolution reaction, well-defined anodic peaks were observed for the oxidation of purine and pyrimidine bases in acid medium, whereas at AD BDD the oxidation peak of thymine was overlapped with the anodic current of oxygen evolution. The chromatograms of adenine, guanine, cytosine, thymine and 5-methylcytosine mixture were well resolved by using a silica-based column and a solution of 5% acetonitrile in 100 mM ammonium acetate buffer (pH 4.25) as the mobile phase. The detection was carried out at AO BDD electrode at an applied potential of 1.6 V versus Ag/AgCl. Linear calibration curves were obtained within the concentration range from 0.1 to 10 μM with the limits of detection (S/N = 3) ranging from 26.3 to 162.1 nM, resulting in an order of magnitude higher sensitivities than those at conventional electrodes. HPLC analysis with diamond amperometric detector was successfully applied for determination of 5-methylcytosine in real DNA samples with high reproducibility. No deactivation of the electrode was found during cyclic voltammetric and HPLC measurements, indicating the high stability for analysis of biological samples. 相似文献
992.
C. F. M. Borges M. Asmann E. Pfender J. Heberlein 《Plasma Chemistry and Plasma Processing》1998,18(2):305-324
The effects of process parameters on diamond film deposition have been considered in an atmospheric-pressure dc thermal plasma jet reactor. Two different precursor injection systems have been evaluated, counterflow and side injection. The precursor flow rate using ethanol has been found to strongly affect crystal size as well as orientation of crystal growth planes. Further, crystal size on sharp edges has been found to be up to five times larger than on planar surfaces. The effects of substrate geometry on the morphology and area of deposited diamond have been investigated as well. The results of this study show that dc thermal plasma jets can provide high diamond deposition rates, for example on wires and drills, although crystal size and film thickness show substantial variation. 相似文献
993.
《Analytical letters》2012,45(14):2673-2682
Abstract This work describes an analytical methodology for the determination of nitrite ions in aqueous solutions using boron‐doped diamond electrodes and square wave voltammetry associated with ultrasound radiation. The nitrite ions were oxidized to nitrate ions in Britton‐Robinson buffer solutions 0.1 M, pH 2.0 at 1.0 V versus Ag/AgCl. The voltammetric response of nitrite in the presence of ultrasound showed a peak current five times higher than the obtained in silent conditions. Thus, the detection limit obtained in the presence of radiation was 17 nM (0.782 µg l?1), a small value if compared with that obtained in the absence of ultrasound: 140 nM (6.44 µg l?1). 相似文献
994.
纳米金刚石颗粒对发动机润滑油摩擦学特性的影响 总被引:24,自引:6,他引:24
采用爆炸法合成了超精细金刚石颗粒 ,将金刚石颗粒按一定质量分数分散于普通发动机润滑油 (15W/30 )中形成固 -液二相体系 ,考察了其摩擦学特性 ,并分析了润滑剂的减摩抗磨作用机理 .结果表明 ,在边界润滑条件下 ,由于纳米尺寸效应 ,超精细金刚石颗粒较易渗透到摩擦副表面并形成极薄的固体润滑膜 ,从而使得金刚石颗粒 /发动机润滑油固 -液二相体系表现出优异的承载能力和减摩抗磨性能 相似文献
995.
In situ microwave activation has been applied to the electro-deposition and stripping of palladium metal (which is widely used as a catalyst) at cavitation resistant boron-doped diamond electrodes. Focused microwave radiation leading to heating, boiling, and cavitation is explored as an option to improve the speed and sensitivity of the analytical detection procedure. The deposition and anodic stripping of palladium by linear sweep voltammetry in 0.1 M KCl (pH 2) solution and at boron-doped diamond electrodes is shown to be strongly enhanced by microwave activation due to both (i) the increase in mass transport and (ii) the increase in the kinetic rate of deposition and stripping.The temperature at the electrode surface is calibrated with the reversible redox couple Fe(CN)64−/Fe(CN)63− and found to be reach 380 K. In the presence of microwave radiation, the potential of onset of the deposition of palladium is strongly shifted positive from −0.4 to +0.1 V versus SCE. The optimum potential for deposition in the presence of microwaves is −0.4 V versus SCE and the anodic stripping peak current is shown to increase linearly with deposition time. Under these conditions, the stripping peak current varies linearly with the palladium concentration down to ca. 2 μM. At concentration lower than this a logarithmic variation of the stripping peak current with concentration is observed down to ca. 0.1 μM (for 5 min pre-concentration in presence of microwave radiation). 相似文献
996.
Pratik Joshi Parand Riley K.Yugender Goud Rupesh K. Mishra Roger Narayan 《Current Opinion in Electrochemistry》2022
The electrocatalytic properties of boron-doped diamond (BDD) electrodes have been considered for a variety of sensing applications. The unusual electrochemical properties of BDD include a large potential window, a small background current, and better resistance to fouling than other carbon-based electrodes. The use of BDD for remediation and environmental sensing applications has recently attracted the interest of the sensor research community. This review focuses on recent developments that involve the use of BDD as an environmentally friendly sensing material for environmental analysis. The electrochemical properties of boron-doped diamond that has undergone surface modification (e.g., with metals or enzymes) will be considered. Recent achievements involving the use of BDD electrodes for detecting pesticides, mycotoxins, peroxides, and phenolic compounds are considered. 相似文献
997.
998.
999.
Reinaldo F. Teófilo Helder J. Ceragioli Alfredo C. Peterlevitz Leonardo M. Da Silva Flavio S. Damos Márcia M. C. Ferreira Vitor Baranauskas Lauro T. Kubota 《Journal of Solid State Electrochemistry》2007,11(10):1449-1457
The electrochemical properties of boron-doped diamond (BDD) polycrystalline films grown on tungsten wire substrates using
ethanol as a precursor are described. The results obtained show that the use of ethanol improves the electrochemistry properties
of “as-grown” BDD, as it minimizes the graphitic phase upon the surface of BDD, during the growth process. The BDD electrodes
were characterized by Raman spectroscopy, scanning electronic microscopy, cyclic voltammetry (CV), and electrochemical impedance
spectroscopy (EIS). The boron-doping levels of the films were estimated to be ∼1020 B/cm3. The electrochemical behavior was evaluated using the and redox couples and dopamine. Apparent heterogeneous electro-transfer rate constants were determined for these redox systems using the CV and EIS techniques. values in the range of 0.01–0.1 cm s−1 were observed for the and redox couples, while in the special case of dopamine, a lower value of 10−5 cm s−1 was found. The obtained results showed that the use of CH3CH2OH (ethanol) as a carbon source constitutes a promising alternative for manufacturing BDD electrodes for electroanalytical
applications. 相似文献
1000.