Analytical Chemistry Commons^™

Analyses On Spm Images And Theoretical Investigations On Oxygen Vacancy Concentration Of Light-Induced Nanostructured Titania Super Hydrophilic Films, Ren-Jie Zeng, Zhong-Hua Lin, Zhi-Min Fang

Journal of Electrochemistry

A typical nanostructured titania super hydrophilic film was chosen for general char2 acterization employing a Scanning Probe Microscope (SPM) and an electrochemical measurement system. Following from the principles of the solid state chemistry and nanomechanics, intensive theoretical. analyses on the SPM images, the oxygen vacancy concentration sand the mechanism of the super hydrophilicity were made; further illuminationsona reactionequation of titania defect formation, a tentative universal surface physical mode for the wet-ability, a concept, amphiphobic-ity, and surface design were carried out after the author’ sprevious introduction and proposal in the end of 1999.

Study Of Electrochemistry Of Aloe-Emodin And Determination Of It With 1.5th Order Derivative Anodic Stripping Voltammetry, Xin-Hua Lin, Li-Ying Huang, Wei Chen, Hong-Bin Luo, Bin Qiu, Chun-Yan Li

Journal of Electrochemistry

In 0.1 mol/L, HAc solution (pH=2.89), the voltammetric behaviours of aloeemodin at a glassy carbon electode has been studied, One pair of current peak of the voltammogram maybe attributed to a quasireversible two-electron transfer of aloeemodin molecules at the glassy carbon electrode. A new method, the derivative anodic stripping voltammetry, for aloeemodin de-termination is described. The adsorptive potential of aioeemodin is -0. 80 V (vs. SCE) , while itsstripping potential is -0.38 V (vs. SCE). The peak current is propotionat to the concentration ofaloeemodin over the range of 2.0 x10⁷~8.0 x10⁶ mol/L. The method is simple, rapid …

Simultaneous Determination Of Enantiomers Of Structurally Related Anticholinergic Analogs In Human Serum By Liquid Chromatography–Electrospray Ionization Mass Spectrometry With On-Line Sample Cleanup, Vladimı́R Čápka, Yan Xu

Chemistry Faculty Publications

Trihexyphenidyl, biperiden and procyclidine are anticholinergic drugs produced as racemates for the treatment of Parkinson’s disease. This paper describes a simple and sensitive LC–MS method for the simultaneous determination of these compounds in human serum. An on-line sample clean-up procedure was used, where serum samples were directly injected into a “restricted-access media” pre-column. After the exclusion of the serum proteins, the drug molecules were eluted to a β-cyclodextrin analytical column for chiral separation. The quantitation was done by electrospray ionization MS using diphenidol as an internal standard. The method developed has limits of detection of 1 ng/ml, at least two-orders-of-magnitude …

Simultaneous Determination Of Gold(Ⅲ) And Copper(Ⅱ) With Two-Way Stripping Voltammetry, Rong-Zong Hu, Dong-Ping Wei, Guang Wei, Yue-Ying Liu

Journal of Electrochemistry

A novel Two-way Stripping Voltammetry method for simultaneous determination of Au³⁺ and Cu²⁺ was reported in this paper. Because of the strongly electrostatic attraction of carbon paste electrode towards Au(Ⅲ) ion at positive potential and the biochemical contribution of Gram-positive bacteria strain DO1, the ion can be determined by cathodic stripping voltammetry. At the same time, Cu(Ⅱ) is reduced readily under the catalysis of ultra-fine gold particles, thereafter it can be determined by anode stripping voltammetry. There is no interference between the determination of Au³⁺ and Cu²⁺ . A perfect liner relationship between the concentrations of …

In Situ Ftir Reflection Spectroscopy Of Bioelectrode, Sa-Ying Dong, Guang-Yu Zhao, Yuzhu Gao, Guang-Zhang Chen, Ming-Xiang Lv

Journal of Electrochemistry

In situ FTIR reflection spectroscopy was used to study mediated enzyme electrode and immunoelectrode. We determined and analyzed IR characteristic spectra of GOD and glucose by the use of potential difference spectra and single beam subtractive spectra. At last, we explored the IR absorption characters of enzyme-immunoelectrode.

Determination Of Hydrogen Diffusion Coefficient In Metal Hydride Electrode With Electrochemical Impedance Spectroscopy, Xian-Xia Yuan, Nai-Xin Xu

Journal of Electrochemistry

Electrochemical impedance spectroscopy was employed to determine the hydrogen diffusion coefficient in MlNi _3.75Co _0.65 Mn_0.4Al_0.2 metal hydride electrode with various states of charge (SOC) at room temperature and with 50% SOC at various temperatures. It was found that hydrogen diffusion coefficient in this electrode decreases with the increase in SOC at ambient temperature, and for the electrode with 50% SOC, hydrogen diffusion coefficient increases with the increase of temperature and the activation energy for hydrogen diffusion in it is 35 kJ/mol.

Electrochemical Impedance Spectroscopy Study On A3 Steel In Anti-Corrosive Pigment Extract Solution, Zhi-Jun Gu, Yong-Gui Liao, Zhi-Gang Zhang, Qi-Long Guo, Fang-Teng Su, Wen-Yun Hu, Yan-Zhen Chen

Journal of Electrochemistry

The corrosion behaviors of A₃ steel in different pH, 3.5%NaCl, modified zinc phosphate and aluminum triphosphate extract solutions have been studied by EIS. Results show:(a) The resistance increases with the increase of pH value under the same circumstances, but the capacity is the reverse. (b) Zinc phosphate, because of its low solubility, shows no inhibitive performance for A₃ steel in 3.5% NaCl extract solutions. (c) Aluminum triphosphate has good inhibitive performance for A₃ steel in 3.5% NaCl extract solutions at a pH of 6, probably because the triphosphate ion can complex with the corrosion-product, such as ferric …

Comparison In Surface Enhanced Raman Scattering On Salicylideneamine Between Silver And Gold Colloid And Silver Mirror Substrate, Bing Zhao, Yukihiro Ozaki

Journal of Electrochemistry

This work studied the potential difference and galvanic currents on particulate contamination of the abrasive on the patterned surface and on corrosion behaviors of TiN and W. The polarization curves of TiN and W were, respectively, obtained in 0.01mol/L KNO₃ solutions in the absence and presence of three typical oxidants (H₂O_2, KIO₃, Fe(NO₃)₃) by DC polarization technique. The corrsion potentials and galvaniccurrents were measured when TiN and W were placed in a specially designed electr-chemical cell to form electro-couple. The preliminary results revealed that the corrosionrate of TiN-W electro-couple significantly …

The Dependence Of Relative Enhancement Of Sers Bands On Temperature, Ling Huang, Jian Shen, Tsing Yu, Qing-Jin Meng

Journal of Electrochemistry

The adsorption and binding behavior of 2,5-dimercapto-1,3,4-thiadizole(DMTD) on silver surface was studied by near-infrared Fourier Transfer surface enhanced Raman scattering(NIR FT-SERS) technique. It was found that the relative intensities of the SERS bands change regularly with the increasing of temperature, which suggests the transformation of the tautomers or the re-orientation of DMTD molecules in the surface layer.

Determination Of Lysophosphatidic Acids By Capillary Electrophoresis With Indirect Ultraviolet Detection, Yi Lung Chen, Yan Xu

Chemistry Faculty Publications

Lysophosphatidic acid (LPA) is the simplest form of lysophospholipid. Molecular species of LPA have been identified as the potent components in the ovarian cancer activation factor. The elevated plasma LPAs may be used as potential biomarkers for the early detection of ovarian cancer. This paper is the first report on the quantitative analysis of molecular species of LPA using capillary electrophoresis. In this work, the separation of LPAs was achieved within 14 min in an adenosine monophosphate-borate–methanol–water solution, and the measurement was accomplished by indirect UV detection. With LPA (D) as internal standard, the method had linear calibration ranges for …

The Applications Of Confocal Raman Micro-Spectroscopy For Study Of Practical Electrode Materials, Yong Yang, Wei Chu, Jun-Min Nan, Xun-Guang Chen, Zu-Geng Lin

Journal of Electrochemistry

Some recent research work about applications of confocal Raman micro spectroscopy for study of practical electrode materials carried out in our lab has been briefly introduced. The examples include study of electrochemical Li⁺ intercalation process, characterization of surface oxide film on AB₅ type electrodes and passive film and pitting corrosion of Rebar electrodes.

Confocal Microprobe Raman Spectroscopy For Investigating The Electrochemical Interface, Bin Ren, Feng-Ming Liu, Xu-Feng Lin, Zhong-Qun Tian

Journal of Electrochemistry

The invention of the surface enhanced Raman spectroscopy (SERS) in the mid of 1970s, opened an entirely new and very promising area. However, it was found that SERS of practical application in electrochemistry can only be found on noble metal surfaces, such as Ag, Au and Cu that exhibit huge surface enhancement. This greatly limits the application of SERS in electrochemistry.

Raman And Afm Characterization Of Au And Cu Nanorod And Nanowire Arrays, Jing Tang, Jian-Lin Yao, Kuan-Hong Xue, De-Yin Wu, Long-Gang Lin, Yu-Xiong Jiang, Bin Ren, Xin Xu, Bing-Wei Mao, Zhong-Qun Tian

Journal of Electrochemistry

Recently metal nanowires (nanorods) have aroused tremendous interest because of their novel properties and potential applications in wide fields Many two-dimensional nanowire arrays of semiconductors and metals with different diameter and length have been made by using template synthesis method.

Surface-Enhanced Raman Spectroscopy Of Metallotetraphenyl Porphyrins Adsorbed On Ag2O And Silver Colloids, Ying-Hui Zhang, Dong-Ming Chen, Tian-Jing He, Fan-Chen Liu

Journal of Electrochemistry

The biological significance of porphyrins and metalloporphyrins has stimulated intensive investigations on these compounds for many years. On the other hand, porphyrins and metalloporphyrins also have extensive applications in many other fields such as chemical modified electrodes, organic photovoltaic devices and biomimetic catalysis. The adsorption behavior and chemical reactions of metalloporphyrins on surfaces or interfaces are very important for these applications.

Electrochemical Impedance Spectroscopy Studies On Inhibitive Performance Of Aluminum Triphosphate Pigment, Yong-Gui Liao, Zhi-Jun Gu, Zhi-Gang Zhang, Qi-Long Guo, Fang-Teng Su

Journal of Electrochemistry

The epoxy coatings on A₃ steel sheets containing calcite or aluminum triphosphate (AlTP), were investigated by Electrochemical Impedance Spectroscopy (EIS). The results showed that calcite pigment is not an inhibitor, but an extender pigment, and that AlTP pigment can considerably enhance the protective performance of epoxy coating. The triphosphate ion at the interface between the steel substrate and the coating can complex with the corrosion product, such as ferric and ferrous ions, and form a compact protective film which effectively separates the steel substrate from the aggressive media.

Rhodium As A Ubiquitous Substrate For Surface Enhanced Raman Spectroscopy, Bin Ren, Xu-Feng Lin, Zhong-Qun Tian

Journal of Electrochemistry

Raman Spectroscopy is a powerful technique in characterizing the molecular structure at the molecular level. However, only after the discovery of surface enhanced Raman scattering (SERS) effect, has it become one of the most widely used technique in surface sciences. The limitation that only Ag, Au and Cu can produce prominent SERS signal of practical significance, greatly hinders the application of this technique. Recently our group has made great progress in extending SERS to pure transition metal surfaces, such as Pt, Ni, Fe, Co etc.

Two-Dimensional Surface Raman Imaging Of A Roughened Iron Electrode In Saline Water, Pei-Gen Cao, Jian-Lin Yao, Jun-Wei Zheng, Bin Ren, Ren-Ao Gu, Zhong-Qun Tian

Journal of Electrochemistry

The analysis of the composite and distribution of iron oxide due to pit corrosion in saline solutions (3.4% NaCl) is of great importance. Many electrochemical methods, XPS, and other photoelectronic techniques have been applied to this domain. Surface enhanced Raman scattering (SERS) spectroscopy can provide the vibrational information of surface species with high sensitivity and is very useful in the study of surface chemistry of iron. Notwithstanding, the application of SERS in iron corrosion is hampered for its SERS-inactivity. Efforts have been devoted to extend the use of SERS to the study of iron.

The Charge Transfer Effect Of Sers Induced By The Electrochemical Hydrogen Evolution Reaction, Feng-Ming Liu, Qi Han, Yan-Xia Chen, Qi-Ling Zhong, Bin Ren, Zhong-Qun Tian

Journal of Electrochemistry

As one of the important mechanisms of SERS, the charge transfer (CT) enhancement requires the strong interaction of the adsorbed species with the substrate in order to permit the transition of charge between the metal Fermi level (energy state) and the molecular orbital. The high enhancement needs the match of the energy gap between the Fermi level (or surface state) and the orbital energy level of the adsorbed molecules with the energy of the incident light. The electrode Fermi level is usually adjusted by the applied potential to satisfy the CT resonance. For the electrochemical reaction process, the frontier orbital …

Raman Spectroelectrochemical Study On Bioactive Molecules, Xiao-Wei Cao, Hai-Feng Yang, Zhe Su Meng Xiao Yun Wang, Xia-Qin Wu, Zong-Rang Zhang

Journal of Electrochemistry

Electron-transfer reaction is known to be one of the key reactions for generating biological functions. Mechanism revelation at a molecular level of such kind reactions is to be very helpful for us to understand life essence. In fact, surface enhanced Raman scattering (SERS) is one of the most powerful tools for the study on metal-electrolyte and metal-vacuum interfaces since 1970's. Moreover, Raman spectroscopic study in enzymology has provided attractive results during last twenty-five years.

In Situ Raman Spectroelectrochemical Characterization Of The Prussian Blue/Platinum Modified Electrode, Xiao-Wei Cao, Rong Wang, Gui-Hua Wang, Zong-Rang Zhang

Journal of Electrochemistry

Prussian Blue is known to be deposited electrochemically on the electrode surface, producing a dense redox active layer. Since the Prussian Blue modified electrode was first reported by Neff in 1978, different in situ spectroelectrochemical techniques have been widely used to investigate its electrochemical mechanism. But no research work related to the in situ Raman spectroscopic studies on it has been reported. In this paper we try to characterize the nature of thin Prussian Blue films on platinum substrates with in situ Raman spectroelectrochemical technique.

Adsorption And Oxidation Of Ethanol On Nm-Pt/Gc Electrode Ii. Eqcm And In-Situ Ftir Spectroscopic Studies In Acid Media, Guo-Liang Chen, Sheng-Pei Chen, Zhi-You Zhou, Chun-Hua Zhen, Shi-Gang Sun

Journal of Electrochemistry

The adsorption and oxidation of ethanol on nm Pt/GC electrode in acid solutions containing 0.1 mol·L ^-1 H₂SO₄ +0.1 mol·L ^-1 CH₃CH₂OH was investigated by using cyclic voltammetry, EQCM and in situ FTIR spectroscopy. The experimental results demonstrated that the oxidation of CH₃CH₂OH is closely relaed to solution acidity and oxygen species on electrode surface; CH₃CH₂OH was oxidized on nm Pt/GC electrode in acidic media via a dual path reaction mechanism, i.e . CH₃CH₂OH may be oxidized into CO₂ through …

Fabricating And Imaging Carbon-Fiber Immobilized Enzyme Ultramicroelectrodes With Scanning Electrochemical Microscopy, David O. Wipf, Fuyun Ge, Robert C. Tenent

Publications

The scanning electrochemical microscope (SECM) is used to image the activity of enzymes immobilized on the surfaces of disk-shaped carbon-fiber electrodes. SECM was used to map the concentration of enzymatically produced hydroquinone or hydrogen peroxide at the surface of a 33-mm diameter disk-shaped carbon-fiber electrode modified by an immobilized glucose-oxidase layer. Sub-monolayer coverage of the enzyme at the electrode surface could be detected with micrometer resolution. The SECM was also employed as a surface modification tool to produce microscopic regions of enzyme activity by using a variety of methods. One method is a gold-masking process in which microscopic gold patterns …

Preliminary X-Ray Diffraction Studies Of The Transcriptional Inhibitory Antibody Fab41.4, Johanna Mazlo, Robyn L. Stanfield, Ian A. Wilson, Steven H. Hinrichs, John J. Stezowski

Department of Chemistry: Faculty Publications

The binding of transcription factor ATF-1 to DNA contributes to gene expression and regulation of cell growth. Antibody Mab41.4, raised against ATF-1, and its derivatives Fab41.4 and scFv41.4 inhibit specific DNA binding in vitro and induce apoptotic death of tumor cells in vivo. Structural studies of Fab41.4 were performed to gain insight into the mechanism of action of this potentially therapeutic antibody. The optimal conditions for crystallization of Fab41.4 were determined. Crystals were needle-like in appearance, displayed C2 space-group symmetry and diffracted to a resolution of 1.6 Å. The unit-cell parameters were determined to be a = 186.64, b = …

Cerumen Composition By Flash Pyrolysis-Gas Chromatography/Mass Spectrometry, Craig N. Burkhart, Michael A. Kruge, Craig G. Burkhart, Curtis Black

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

Objective: To assess the chemical composition of cerumen by flash pyrolysis-gas chromatography/mass spectrometry.

Study Design: Collected earwax specimens were fractionated into residue and supernatant by means of deoxycholate. This natural bile acid produces significantly better disintegration of earwax in vitro than do presently available ceruminolytic preparations, and also has demonstrated excellent clinical results in vivo to date.

Patients: The sample for analysis was obtained from a patient with clinical earwax impaction.

Results: The supernatant is composed of simple aromatic hydrocarbons, C₅-C_{l 7} straight-chain hydrocarbons, a complex mixture of compounds tentatively identified as diterpenoids, …

Production Of A Novel Copper-Binding Ligand By Marine Synechococcus (Cyanobacteria) In Response To Toxic Concentrations Of Copper, Arunsi C. Brown, Andrew S. Gordon

Virginia Journal of Science

Marine Synechococcus spp. are extremely sensitive to copper toxicity. Some strains have been shown to produce high-affinity, extracellular ligands of unknown structure which form complexes with free cupric ion. They are also known to produce metallothioneins (MT) in response to cadmium and zinc stress. In the present study, marine Synechococcus PCC 73109 (Agmenellum quadruplicatum BG-1) (Van Baalen) was exposed to three concentrations of CuSO₄ for various times. Size exclusion chromatography, atomic absorption spectrophotometry, and reverse phase HPLC were used to isolate an intracellular copper binding ligand of low molecular weight (< 6,500 Da). The ligand was detected after exposure to ≥ 8 μM CuSO₄ for 2 hr in BG-11 medium. …

Use Of Py-Gc/Ms Analysis Techniques In Animal Waste Management: A Preliminary Survey Of Dairy Manures, Daniel L. Vaughn, Michael A. Kruge

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The increasing practice of industrial-scale agriculture tends to concentrate large masses of animal waste in relatively compact areas, potentially leading to excessive release of polluting nutrients into waterways during major storms. Anaerobic treatment conditions are generally favored to conserve nitrate N as an agricultural commodity. However, overall N contents in waste are often in excess of crop fertilization needs: storing excess N in soluble nitrate form increases pollution potential. Thus the perceived needs of agriculture and society-at-large become at odds. Organic nitrogen forms (e.g., proteins) are more environmentally stable and are less subject to unintentional release. Although U.S. farmers tend …

Analysis Of Loratadine By Potentiometry And Reverse-Phase High Performance Liquid Chromatography, Kian Yong Puen

Student Works (2000-2009)

A non-aqueous titration method was developed to assay Loratadine bulk active and a High Performance Liquid Chromatography (HPLC) method was developed to determine Loratadine's manufacturing impurity. The HPLC method was also suitable for simultaneously assay and related substance determination of Loratadine pharmaceutical preparations. In the tritation method, glacial acetic acid was chosen as an amphiprotic solvent. Loratadine ionised in glacial acetic acid; the conjugated base of acetic acid (Ac·), was then titrated with standardised perchloric acid. The method was validated found to be precise, linear and robust. Reverse-phase HPLC method using a Novapak Cl8 column with a CH3CN: I0mM K2HPO4 …

Impedance Feedback Control For Scanning Electrochemical Microscopy, David O. Wipf, Mario A. Apuche-Avlles

CAS Publications

A new constant-distance imaging method based on the relationship between tip impedance and tip-substrate separation has been developed for the scanning electrochemical microscope (SECM). The tip impedance is monitored by application of a high frequency ac voltage bias between the tip and auxiliary electrode. The high frequency ac current is easily separated from the dc level faradaic electrochemistry with a simple RC filter, which allows impedance measurements during feedback or generation/collection experiments. By employing a piezo-based feedback controller we are able to maintain the impedance at a constant value and, thus, maintain a constant tip-substrate separation. Application of the method …

Development Of Amperometric Enzyme Electrodes For Glucose And Hypoxanthine., Eilish Broderick

Theses

This thesis is concerned with the immobilisation of enzymes on electrosynthesised poly (o- phenylenediamine) membranes for use on amperometric electrodes. The thesis opens with a discussion of the basic principles of enzymology and a review of a diverse range of biosensors, followed by a consideration of amperometry as governed by the Cottrell equation.

Glucose oxidase and horseradish peroxidase were co-immobilised in poly (o-phenylenediamine) on platinum electrodes at + 0.6 V versus Ag/AgCl. Using this approach the enzymes are entrapped in a strongly adherent, highly reproducible thin membrane, of thickness approximately 10 nm. This one-step procedure produces a glucose sensor with …

Analysis Of Wine For Penicillin, Gary Morris, James Yuan, Roy Williams

Chemistry & Biochemistry Faculty Publications

This study addresses the question of whether the antibiotic Penicillin, which is produced by the common mold Penicillium notatum, could possibly become a contaminate of wine during the fermentation process. The significance of this study is related to the potential health effects this agent might produce in those consumers who have an allergic response to Penicillin. It has been estimated that between 6% and 8% of the American population is subject to this type of allergic response. A method is developed for the detection of penicillin in wines using high-pressure liquid chromatography. We demonstrate that penicillin G hydrolyzes rapidly …