bluuebunny/crossref_metadata_2025 huggingface dataset:
Review: Multipoint binding and heterogeneity in immobilized metal affinity chromatography
Authors: Johnson Robert D. , Arnold Frances H.
Published: February 2006

Studies carried out using engineered proteins clearly demonstrate that adsorption to derivatized surfaces involves multiple interactions between functional groups on the protein and complementary sites distributed on the surface. The fact that adsorption involves multipoint interactions has important implications for the design of separations processes and for the interpretation of heterogeneity in biological recognition phenomena. Increasing the density of surface metal sites (immobilized copper ions) is found to be functionally equivalent to increasing the number of metal‐coordinating groups on the protein (histidines and deporotonated amines), m in that both processes increase the likelihood of simultaneous interactions between the protein and the surface. A consequence of multiple‐site interactions is a significant in crease in protein binding affinity that depends on the arrangement of surface sites. A protein will show the highest affinity for arrangements of surface sites which best match its own pattern of functioal groups and will show lower affinity for less optimal arrangements, resulting in binding that is inherently heterogeneous. We have found that reversible protein adsorption in immobilized metal affinity chromatography (IMAC) is described by the Temikin model, which characterizes binding heterogeneity by a uniform distribution of binding energies over the population of surface binding sites. © 1995 John Wiley & Sons, Inc.
Synthesis, Crystal Structure, and Solid State NMR Spectroscopic Investigation of New Oxonitridosilicates of the Solid Solution Series Ba4‐xCaxSi6N10O.
Authors: Stadler Florian , Oeckler Oliver , Schnick Wolfgang
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A New Family of Binary Layered Compounds of Platinum with Alkali Metals (A: K, Rb, Cs).
Authors: Karpov Andrey , Jansen Martin
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
The Monohydrate of Basic Mercuric Nitrate, [Hg(OH)](NO3)(H2O).
Authors: Nolte Matthias , Pantenburg Ingo , Meyer Gerd
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Electronic and Crystallographic Properties of the System CeY2Ni9Dx (0 ≤ x ≤ 8.7) Measured by X‐Ray Absorption Spectroscopy.
Authors: Latroche M. , Paul‐Boncour V. , Percheron‐Guegan A.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Dipotassium Tetrachromate(VI), K2Cr4O13.
Authors: Casari Barbara M. , Langer Vratislav
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Distortion of the fcc lattice in Superstoichiometric β‐YH2+δ and Cubic YH3‐η Thin Films.
Authors: Carsteanu A.‐M. , Rode M. , Zur D. , Schoenes J. , Borgschulte A. , Westerwaal R.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Neutron Diffraction Investigations and Magnetic Properties of LnNi3.5Al1.5 Compounds and Their Hydrides (Deuterides).
Authors: Bououdina M. , Sorgic B. , Quladdiaf B. , Skryabina N. , Fruchart D.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Structure and Magnetism of a New Series of UTSn Hydrides.
Authors: Miliyanchuk K. , Havela L. , Kolomiets A. V. , Andreev A. V.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Hydrogenation and Crystal Structures of the Nd(Ni1‐xCux)(In1‐yAly) Intermetallics and Their Hydrides.
Authors: Riabov A. B. , Denys R. V. , Sato Masashi , Delaplane R. G. , Yartys V. A.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Crystallographic and Thermodynamic Study of La0.55Y0.45Ni5—H2, a Candidate System for Hydrogen Buffer Tanks.
Authors: Challet S. , Latroche M. , Percheron‐Guegan A. , Heurtaux F.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
H‐Sorption in MgH2 Nanocomposites Containing Fe or Ni with Fluorine.
Authors: Deledda S. , Borissova A. , Poinsignon C. , Botta W. J. , Dornheim M. , Klassen T.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Kinetic Studies of the Decomposition of NaAlH4 Doped with a Ti‐Based Catalyst.
Authors: Kircher O. , Fichtner M.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Thermodynamic Properties and Absorption—Desorption Kinetics of Mg87Ni10Al3 Alloy Synthesized by Reactive Ball Milling under H2 Atmosphere.
Authors: Doppiu S. , Solsona P. , Spassov T. , Barkhordarian G. , Dornheim M. , Klassen T. , Surinach S. , Baro M. D.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Two New Polyoxovanadate‐Supported Transition Metal Complexes: [Zn(en)2][Zn(en)2(H2O)2] [{Zn(en)(enMe)} As6V15O42(H2O)] ×4H2O and [Zn2(enMe)2(en)3] [{Zn(enMe)2}As6V15O42 (H2O)]×4H2O.
Authors: Zheng Shou‐Tian , Chen Yong‐Mei , Zhang Jie , Yang Guo‐Yu
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Ortho‐Chalcogenotetrelate Anions as Chelating Ligands: Syntheses and Characterization of [K6(MeOH)9][Sn2Se6] [Cr(en)2(SnSe4)]2, [Na(H2O)4][Cr(en)3]2 [GeS3OH]2[Cr(en)2(GeS4)], and [Ba(H2O)10] [{Cr(en)}2(GeSe4)2].
Authors: Melullis Maike , Brandmayer Michael K. , Dehnen Stefanie
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
New Aquapentachlorochromate(III) Compounds: K2[CrCl5(H2O)] and (NH4)2[CrCl5(H2O)].
Authors: Casari Barbara M. , Eriksson Annika K. , Langer Vratislav
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
High‐Pressure Synthesis and Energetics of MgCu with a CsCl‐Type Structure.
Authors: Takamura H. , Kakuta H. , Goto Y. , Watanabe H. , Kamegawa A. , Okada M.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Aryl Palladium Carbene Complexes and Carbene—Aryl Coupling Reactions.
Authors: Albeniz Ana C. , Espinet Pablo , Manrique Raul , Perez‐Mateo Alberto
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Chiral Oxazaborolidine‐Catalyzed Asymmetric Borane Reduction of Alkyl 4‐Dialkylaminophenyl Ketones
Authors: Xu Jia‐Xi , Lan Yu , Wei Tie‐Zheng , Zhang Qi‐Han
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Exploiting C3‐Symmetry in the Dynamic Coordination of a Chiral Trisoxazoline to Copper(II): Improved Enantioselectivity, and Catalyst Stability in Asymmetric Lewis Acid Catalysis.
Authors: Foltz Carole , Stecker Bjoern , Marconi Guido , Bellemin‐Laponnaz Stephane , Wadepohl Hubert , Gade Lutz H.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A Correlation Study of Bisphosphine Ligand Bite Angles with Enantioselectivity in Pd‐Catalyzed Asymmetric Transformations.
Authors: Raghunath Malati , Zhang Xumu
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Efficient Dynamic Kinetic Resolution of Secondary Amines with Pd on Alkaline Earth Salts and a Lipase.
Authors: Parvulescu Andrei , De Vos Dirk , Jacobs Pierre
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Domino Michael Addition‐Carbene Rearrangement—Cyclization Reaction of 1‐Alkynyl(aryl)‐λ3‐bromanes with 2‐Mercapto‐1,3‐benzazoles.
Authors: Ochiai Masahito , Tada Norihiro
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Cycloaddition of 4,5‐Dihydrooxazol‐5‐one Derivatives to 4‐Methylbenzene‐1,2‐dithiol.
Authors: Tikdari A. M. , Fozooni S. , Vazee H. , Hamidian H.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Rearrangements of N‐Ylide Generated from 1‐Ethoxycarbonylmethyl‐1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridinium Chloride (III).
Authors: Soldatova S. A. , Akbulatov S. V. , Gimranova G. S. , Rudakov Yu. O. , Polyanskii K. B. , Soldatenkov A. T.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Photochemical Decomposition of Nalidixic Acid in Water.
Authors: Bark Ki‐Min , Kim Yong‐Sung , Park Chul‐Ho , Lee Hyeong‐Chul , Park Hyoung‐Ryun
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Transition‐Metal‐ and Organic‐Solvent‐Free: A Highly Efficient Anaerobic Process for Selective Oxidation of Alcohols to Aldehydes and Ketones in Water.
Authors: Gogoi Pranjal , Konwar Dilip
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Oxidant‐Free Oxidation: Ruthenium Catalyzed Dehydrogenation of Alcohols.
Authors: Adair Gareth R. A. , Williams Jonathan M. J.
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Stereochemical Course of the Allylic Hydroxylation: Reaction of 1‐tert‐Butyl‐4‐alkylidenecyclohexanes with Selenium Dioxide.
Authors: Park Gyoosoon , Hwang Jang Cheol , Jung Woo Sik , Ra Choon Sup
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Mild and Efficient Deoxygenation of Epoxides with Bis(cyclopentadienyl)titanium(IV) Dichloride‐Indium System.
Authors: Choi Kwang Hyun , Choi Kyung Il , Kim Joong Hyup , Yoon Cheol Min , Yoo Byung Woo
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Mild and Efficient Direct Aromatic Iodination.
Authors: Johnsson Richard , Meijer Andreas , Ellervik Ulf
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Pd/C‐Catalyzed Oxidative Alkylation of Secondary Alcohols with Primary Alcohols.
Authors: Cho Chan Sik , Ren Wen Xiu , Shim Sang Chul
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Highly Regio‐ and Stereocontrolled SN2′ Reactions of gem‐Difluorinated Vinyloxiranes with Monoalkylcopper Reagents.
Authors: Ueki Hisanori , Chiba Takashi , Yamazaki Takashi , Kitazume Tomoya
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Mixed Organofluorine—Organosilicon Chemistry. Part 14. Mild Synthesis of β‐Amino‐α,α‐difluoro Ketones from Acylsilanes and Trifluoromethyltrimethylsilane in a One‐Pot Imino Aldol Reaction.
Authors: Jonet Sylvain , Cherouvrier Franck , Brigaud Thierry , Portella Charles
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Naphthofuroquinone Derivatives: DNA Topoisomerase‐I Inhibition and Cytotoxicity.
Authors: Cho Heeyeong , Park Su‐Jin , Lee Kee‐In
Published: February 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Investigating von Kries‐like adaptation using local linear models
Authors: Finlayson G. D. , Hordley S. D. , Alsam A.
Published: February 2006

In this article we explore the conditions under which a von Kries‐like model of color constancy is exact. This investigation is motivated by the fact that in practice the model has been shown to work well for a wide range of imaging devices despite the fact that previous analysis of the necessary and sufficient conditions for the model to work predicts that it should perform poorly for real lights and surfaces. We present a modified theory that reconciles this apparent contradiction and that is based on the observation that von Kries‐like adaptation treats sensor responses independently of one another. Starting from this point we show how to recover, for a single sensor, set of surfaces, and reference illuminant, the set of von Kries illuminants: all lights for which von Kries‐like adaptation is a perfect model of illumination change. To help us in this task we use a linear model of surface reflectance, but importantly, we use a local model, that is, a model derived by looking at reflectance only in the region to which the sensor of interest is sensitive. Adopting such a model and treating sensors independently of one another, we show that our new theory accurately predicts the good practical performance of a von Kries‐like model. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 90–101, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20186
The use of reflectance measurements in the determination of fixation of reactive dyes to cotton
Authors: Ahmed N. , Oulton D. P. , Taylor J. A.
Published: February 2006

The utility of the Kubelka–Munk equation for determining the fixation of reactive dyes to cotton has been assessed. Large K/S values are not linearly related to dye concentration on fabric and thus give an inaccurate assessment of fixed dye. If lower values of K/S are selected, by measuring at a suitable wavelength, a linear relationship exists with the concentration of dye present, even at very heavy depths of shade. Thus, by judicious choice of wavelength, K/S values can provide an accurate and convenient method for the assessment of dye on fabric, provided that a reference fabric sample, with a known concentration of the same dye, is available as a standard for comparison. Significant implications are then revealed for construction scalable models of opaque medium reflectance that are homogeneously linear over wavelength with respect to colorant concentration change. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 117–121, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20189
Appearance variations of textile materials due to different near gray backgrounds
Authors: Agahian Farnaz , Hossein Amirshahi Seyed
Published: February 2006

The preliminary experiments were carried out for investigating the effect of lightness of achromatic background (white, grays, and black) on color appearance attributes (lightness and colorfulness) of some colored fabrics. A series of achromatic backgrounds at eight levels of lightness was provided. Each test color was viewed against these backgrounds and the perceived lightness and colorfulness were evaluated by using the pair comparison method.

The results indicated that the lightness of achromatic background affects perceived lightness and colorfulness. The lightness of tests colors increases when surrounded by dark backgrounds while a consistent trend was not noticed for perceived colorfulness. The results from visual assessment were compared with the predicted results by the CIECAM97s model. The predictions of the model were in agreement with the perceived lightness by visual assessment but there was not any correlation between the results of model and visual assessment for colorfulness.

In the second part of the experiments, a colorimetric match of samples on different backgrounds was carried out by visual judgments as well as implementation of color appearance models in reverse mode. Results from visual trials were significantly different from those predicted by the models. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 133–141, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20190
Experimental study of back‐scattering spectrum of textile structures
Authors: Moussa A. , Dupont D. , Steen D. , Zeng X. , Elias M.
Published: February 2006

The back‐scattered light by textile surfaces mainly depends on their surface state, which is often periodic and directional. The analysis of the reflectance spectra in back‐scattering conditions of two types of structures (yarn, plain and twill weaves) shows the influence of the orientation of these surfaces as well as the back‐scattered angle. In fact, the declination of the yarn orientation in relation to the incidence plane involves an increase of the reflectance factor to reach a maximum value when the yarns are perpendicular to this plane. For woven fabrics, the back‐scattering of surface according to a given orientation primarily depends on its geometrical characteristic in this direction and consequently the used yarn densities. The computation of the ratio of mean quadratic surface roughness h to correlation length l for various used orientations shows the close link between this parameter and the evolution of back‐scattering. The effect of the variation of back‐scattered angle on the back‐scattered light varies with the value of h/l. The comparison between these experimental results and a theoretical study based on Gaussian and isotropic surfaces shows a satisfactory correlation between these two elements with the presence of some cases of discrepancy due to the different natures of the two types of surfaces. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 122–132, 2006
Talking about color … and ethics
Authors: Hutchings John
Published: February 2006

Ethics is the study of the moral value of human conduct. The ethics of colour use has rarely been featured as a topic of concern to the colour community. A limited exception is that of the use of colorants in food. This has in the past received much attention but legislation has now greatly restricted such usage. However, concern is resurfacing, and there are many other examples of the possible misuse of colour in food and the wider environment. This editorial asks questions in three areas of life: the environment, food, and marketing in general. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 87–89, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20204
Preconcentration and determination of lead(II) at crown ether and cryptand containing chemically modified electrodes
Authors: Prabhu Sunil V. , Baldwin Richard P. , Kryger Lars
Published: February 2006

Chemically modified electrodes (CMEs) containing incorporated crown ether and cryptand ligands as modifiers were evaluated for their ability to preconcentrate metal cations prior to quantitation by conventional voltammetric methods. Stable CMEs were formed for 18‐crown‐6, dibenzo‐18‐crown‐6, poly(dibenzo‐18‐crown‐6), dibenzo‐24‐crown‐8, and 2.2.2‐cryptand by mixing the desired amount of the ligand into carbon paste. The resulting electrodes exhibited complexing capabilities that were similar to those of the free ligands. In particular, the CMEs were very reactive toward Pb2+ and Hg2+. Pb2+ uptake was sufficiently strong that a detection limit of 1 μM was obtained following a 20‐sec exposure to the sample and transfer to a blank electrolysis solution for differential pulse voltammetric analysis. Accurate quantitation of micromolar levels of Pb in water and urine reference standards was achieved at the CMEs by means of a simple procedure requiring minimal sample preparation. Finally, the analytical characteristics of CME preconcentration were directly compared to those of the electrodeposition approach ordinarily employed in stripping voltammetry.
An evaluation of ultrathin ring and band microelectrodes as amperometric sensors in electrochemical flow cells
Authors: Bixler John W. , Fifield Michael , Poler Jordan C. , Bond Alan M. , Thormann Wolfgang
Published: February 2006

Gold and platinum ultrathin ring microelectrodes (0.1–0.5 mm thick, 1.5–4 mm diameter) were made by sputtering, from fired metalloorganic paint, and from foil for use as sensors in a thick‐layer wall‐jet flow cell. An end‐on array of three 0.1 μm × 0.5 mm gold band electrodes were mounted parallel to the flow direction in a thin‐layer channel cell. These ultrathin sensors, along with a jet‐centered carbon microdisk, were evaluated in the amperometric flow‐injection mode for temporal stability, calibration sensitivity, detectivity, background signal, and flow rate dependence of the analytical signal using ferrocene samples in acetonitrile containing 10−4–10−2 M TEAP. The detectivity of gold paint ring electrodes made on borosilicate glass was 3–6 nM, an order of magnitude lower than any of the other electrodes tested. Analytical signals from gold paint and foil rings and the carbon microdisk had the best temporal stability. The current for the ultrathin band array in a channel cell was flow rate‐independent, and the exponential dependence of cell current on flow rate was 0.11–0.14 for ultrathin rings in the thick‐layer wall‐jet mode.
The construction and utilization of a simple light‐transparent FTIR spectroelectrochemical cell with thin‐layer chamber
Authors: Kadish K. M. , Mu X. H. , Lin X. Q.
Published: February 2006

The construction and utilization of a simple light‐transparent NaCl thin‐layer FTIR spectroelectrochemical cell for transparency measurements is reported. This cell has a 0.25‐mm optical pathlength and a three‐electrode configuration. The application of this cell for in situ FTIR measurements is demonstrated for the electrooxidation of (OEP)lr(CO)Cl, (TPP)Co(NO), and (TPP)Fe(NO) (where OEP and TPP are the dianions of octaethyl‐ and tetraphenylporphyrin, respectively) in methylene chloride solutions containing 0.1 M tetrabutylammonium perchlorate (TBAP). Under these solution conditions, spectral changes of the investigated compounds can be monitored between 2500 and 800 cm−1. Well‐defined thin‐layer cyclic voltammograms of these investigated complexes and diagnostic IR absorption peaks for bound CO and NO as well as for porphyrin π cation radicals are obtained in CH2Cl2 solutions containing 0.1 M TBAP. These in situ generated data are compared with literature IR data for chemically oxidized metalloporphyrins in the solid state.
Voltammetric characterization and determination of thallium(III,I) at a glassy carbon electrode modified with a film containing iridium oxide
Authors: Cox James A. , Das Basudev K.
Published: February 2006

Cyclic voltammetry of a 0.1 mM PdCl2, 0.2 mM Na2IrCl6 0.2 M K2SO4 mixture at a glassy carbon electrode results in the gradual accumulation of a film, which contains Pd(II) and iridium oxide, that promotes the quasi‐reversible oxidation of Tl(I). Cyclic voltammetry at 5 mV/s yields a peak potential difference of 35 mV at the modified electrode and about 700 mV at bare glassy carbon. The peak current for the linear scan voltammetric oxidation of 0.2 mM TI(I) in 1.0 M NaCl is directly proportional to the square root of scan rate up to 0.1 V/s. Both cyclic voltammetry and rotating disk voltammetry at modified electrodes provide data consistent with a two‐electron oxidation. The modified electrode is suitable for the determination of thallium by differential pulse voltammetry in the micromolar range.
Potentiometric selectivity study of crown ethers containing four ring oxygen atoms and benzoxymethyl or carboxylic acid side chains as ionophores for lithium and potassium
Authors: Attiyat Abdulrahman S. , Christian Gary D. , Bartsch Richard A.
Published: February 2006

Five crown ethers with four ring oxygen atoms and different types of pendant groups were used to prepare ion‐selective electrodes by coating a membrane containing the crown ether on the tip of a silver wire incorporated in a flow cell. A flow injection analysis study was conducted to determine the potentiometric selectivities of the crown ethers for lithium, sodium, potassium, magnesium, and calcium ions. It was found that crown ethers with neutral side arms show selectivities for lithium over other ions, while those of acidic side arms show selectivities for potassium over the other ions. The effect of the addition of trioctylphosphine oxide to the electrode matrix was also investigated. A comparison is made between the potentiometric selectivities of the crown ethers for certain metal ions and their selectivities in extracting the ions into an organic phase.
Ion transfer across water/solidified nitrobenzene interface as amperometric flow detector
Authors: Wang Erkang , Ji Huamin
Published: February 2006

The response characteristics of several ions, usually considered as electroinactive, were investigated at the thin‐layer amperometric detector based on ion transfer across the interface of water/nitrobenzene solidified by polyvinyl chloride and agar. The influence of some factors, such as applied potential, flow rate of mobile phase, and organic solvent in mobile phase, was studied by flow injection analysis of cations (choline, acetylcholine, tetramethylammonium, tetrabutylammonium, and cesium) and anions (ClO, IO, and ReO). The detection limit of the flow injection amperometric detector is in the range of 4 to 40 ng of these ions. Reversed‐phase chromatographic separation of choline and acetylcholine with amperometric detection was demonstrated.
Analytically useful stripping voltammetric behavior of technetium at a thenoyltrifluoroacetone‐modified carbon paste electrode
Authors: Dick Renate , Ruf Heinz , Ache Hans J.
Published: February 2006

The preconcentration voltammetric behavior of technetium at a carbon paste electrode modified with thenoyltrifluoroacetone (TTA) has been investigated. It is demonstrated that enrichment of technetium on the electrode surface by complex formation with TTA is possible. Deposition of Tc(IV) takes place due to a purely chemical reaction resulting probably Tc(TTA)4. Enhanced accumulation occurs if a reductive electrode potential of −0.4 V is applied, which presumably causes fixation in the form of Tc(TTA)3. In the subsequent voltammetric scan a characteristic peak at about −40 and +40 mV, respectively, is obtained. Tc(VII) is not deposited, unless a reduction potential of at least −0.6 V is applied, with the pH of the solution optimally chosen at 3.5. Therefore, it is possible to discriminate between Tc(IV) and Tc(VII).
Microvoltammetric and spectroelectrochemical studies of (TPP)Co oxidation/reduction in toluene and benzene solutions
Authors: Mu X. H. , Lin X. Q. , Kadish K. M.
Published: February 2006

The microvoltammetry and spectroelectrochemistry of (TPP)Co (where TPP is the dianion of tetraphenylporphyrin) are reported in toluene and benzene solutions, and provide the first examples of spectroelectrochemistry in these two low dielectric constant solvents. (TPP)Co undergoes four reversible oxidation‐reduction reactions in toluene or benzene. The reductions involve one‐electron transfers and occur at E1/2 = −0.86 and −2.03 V vs. SCE in both solvents. The oxidations involve the successive reversible abstraction of two electrons and one electron from the initial (TPP)Co species and occur at E1/2 = 1.00 and 1.27 V vs. SCE in both solvents. Each electrode reaction was spectrally and electrochemically characterized in toluene and benzene, and the data in these two solvents are compared to data obtained in CH2Cl2 where (TPP)Co redox reaçtions have been extensively characterized in detail. Special emphasis is placed on comparing the thin‐layer spectra of [(TPP)Co1] in toluene and benzene with that in other solvents commonly used for nonaqueous electrochemical studies.
Mechanistic studies of the deposition and cathodic stripping of thioacetamide at a silver electrode in alkaline media
Authors: Hepel Maria , Bruckenstein Stanley
Published: February 2006

Cathodic stripping experiments of thioacetamide in alkaline solutions, pH = 13, were performed using a rotating silver disk electrode and a silver microelectrode. Applicability of these two electrode systems for the determination of thioacetamide over a wide range of concentrations has been found using the stripping peak of bulk silver sulfide. A further improvement in the detection limit is suggested when only an underpotential deposition layer of silver sulfide is formed during deposition. Then cathodic stripping analysis of thioacetamide below 10−8. M is feasible. The mechanism for the reactions during the deposition and cathodic stripping of thioacetamide in alkaline media at silver electrode has been elucidated.
LCEC determination of the copper protein ceruloplasmin in human serum at a polyaniline chemically modified electrode
Authors: Ye Jiannong , Baldwin Richard P. , Schlager Janis W.
Published: February 2006

A chemically modified electrode (CME) for use in the amperometric detection of the copper protein ceruloplasmin was constructed by electropolymerizing a polyaniline coating onto glassy carbon. The resultant CME, used in liquid chromatographic detection, gave an electrocatalytic response for ceruloplasmin reduction that could be employed directly by itself or could be greatly enhanced by the addition of Fe2+ to the mobile phase. Optimum detection was achieved at an applied potential of −0.10 V vs. Ag/AgCl and with 1 mM Fe2+ in the mobile phase. The detection limit obtained under these conditions was 2 pmol injected, and the response was linear for concentrations at least 2 orders of magnitude higher. The CME retained more than 90% of its initial response to ceruloplasmin over 30 hours of continuous exposure to the chromatographic flowstream. In practice, the liquid chromatography CME response was sensitive and selective enough to permit quantitation of physiologically relevant levels of ceruloplasmin in human serum with no sample pretreatment other than preinjection filtration.
Flow cell based on glucose oxidase‐modified carbon fiber ultramicroelectrode
Authors: Wang Joseph , Li Ruiliang , Lin Meng‐Shan
Published: February 2006

Glucose oxidase‐modified carbon fiber electrodes have been prepared by electrochemical deposition of the enzyme in the presence of a platinum complex. The electrode is incorporated as an electrochemical detector in a flow system, exhibiting a very rapid response to dynamic changes in the glucose concentration. The fast response is attributed to the intimate contact of the biocatalytic and sensing sites. Simultaneous lowering of the overvoltage for hydrogen peroxide oxidation is observed. Various response characteristics are evaluated. The relative standard deviation for 40 repetitive injections over a 60‐min period is 3%. The electrodes remain active over a 20‐day period, are inexpensive and easy to prepare, and hold a great promise as in vivo or disposable glucose probes.
Carbon paste electrode chemically modified by direct admixing of tris[4,7‐diphenyl‐1,10‐phenanthroline]iron(II)
Authors: Hynes Christopher J. , Bonakdar Mojtaba , Mottola Horacio A.
Published: February 2006

Direct incorporation, by admixing, of tris[4,7‐diphenyl‐1,10‐phenanthroline]iron(II) cation and perchlorate as counteranion with carbon paste electrodes resulted in chemically modified surfaces of promising electrochemical behavior. The electrochemical performance of the modified surfaces was characterized by cyclic voltammetry. One reduction peak and one oxidation peak, which were almost pH independent in the 1.00–5.00 pH range, are observed at ca. +1.00 and +1.20 V vs. Ag/AgCl, respectively. The cathodic peak remains constant with successive cycling of the potential, but the less well‐developed anodic peak disappears. The same effect was observed after sustained application (several hours) of a + 1.0 V potential. Perchlorate offers certain advantages as counteranion over salicylate, benzoate, and dodecylbenzenesulfonate. The modified surfaces have a low rate of loss of the complex by leaching and are useful for the catalytic sensing of redox species, particularly gaseous analytes in continuous‐flow systems. The hydrodynamic voltammetric behavior of NO2(g) is presented to illustrate this point.
Trace analysis at clay‐modified carbon paste electrodes
Authors: Wang Joseph , Martinez Teddy
Published: February 2006

Carbon paste electrodes modified with montmorillonite clay are used for the collection of iron(III) from dilute solutions followed by voltammetric quantification of the surface‐bound cation. Open‐circuit conditions are maintained during the ion exchange preconcentration. The surface is regenerated by a brief exposure to a sodium carbonate solution. For 20 preconcentration/measurement/regeneration cycles, the response could be reproduced with 4.8% relative standard deviation. Factors influencing the response, such as electrode composition, preconcentration time, measurement and „cleaning”︁ solutions, ionic strength, coexisting metals, iron concentration, and other variables, have been investigated. A detection limit of 0.2 mg/liter was estimated following 3 min preconcentration. The unusual mechanisms of ion exchange processes at clays should lead to a new class of modified electrodes for preconcentration/voltammetric measurements.
An electroanalytical method for estimation of fish freshness using a flow‐injection system with some immobilized enzyme reactors
Authors: Yao Toshio , Matsumoto Yoshihiro
Published: February 2006

A flow‐injection system is proposed for the estimation offish freshness. The 5′‐adenylic acid deaminase reactor, alkaline phosphatase reactor, and nucleoside phosphorylase‐xanthine oxidase coimmobilized reactor were incorporated at fixed positions in a flow system, which was based on the splitting of the flow after sample injection and subsequent confluence before reaching the peroxidase electrode. Because each channel has a different residence time, two peaks were obtained. The first peak corresponded to the total of hypoxanthine and inosine, and the second peak to the total of hypoxanthine, inosine, inosine‐5′‐monophosphate, and adenosine‐5′‐monophosphate. The index of fish freshness, K, is estimated by

where s1 and s2 represent the sensitivity (nA mM−1) and i1 and i2 represent the peak current (nA) of the first and second peaks, respectively. The measurements could be performed at a rate of 15 samples per hour with satisfactory precision.
Pulsed amperometric detection based on direct and indirect anodic reactions: A review
Authors: Austin‐Harrison Deborab S. , Johnson Dennis C.
Published: February 2006

Pulsed amperometric detection (PAD) is applicable for the quantitative detection of numerous organic compounds that adsorb at noble metal electrodes but cannot be detected satisfactorily by conventional amperometry at constant (dc) applied potential. A multistep waveform is applied in PAD with chrono‐amperometric detection based on faradaic signals, which frequently are produced by surface‐controlled reactions. We briefly review applications of PAD for liquid chromatography and present a unified explanation of the various modes of anodic response.
Submicromolar determination of NADH by means of graphite and glassy carbon electrochemical transducers
Authors: Palleschi G. , Rathore H. S. , Mascini M.
Published: February 2006

Reduced nicotinamide adenine dinucleotide (NADH) has been determined at submicromolar levels (the detection limit was 0.05 μmol/L) by using graphitized and glassy carbon electrodes obtained from different sources. Preliminary studies compared the sensitivity, stability, and reproducibility of such sensors during NADH measurements in linear‐sweep voltammetry as well as at constant applied potential. High purity graphite carbon from Ringsdorff has been found to be the most suitable for NADH oxidation. To regenerate the electrodes after each voltammetric scan, washing with a large volume of distilled water under stirring conditions is required. When the sensitivity of the electrode decreases drastically, the sensor surface must be ground and polished with alumina. The nature of the carbon surface has a pronounced effect on the NADH response.
Comparison of the voltammetric behavior of adsorbed or dissolved unsaturated alcohols at vacuum‐annealed and electrochemically cycled Pt(111) and Pt(polycrystalline) electrodes
Authors: Batina Nikola , Kahn Bruce E. , Lin Chiu‐Hsun , McCargar James W. , Salaita Ghaleb N. , Hubbard Arthur T.
Published: February 2006

These studies compare the voltammetric behavior of solutions and adsorbed layers of the following unsaturated alcohols: benzyl alcohol (BZA), 4‐pyridylcarbinol (4PC), allyl alcohol (AA), propargyl alcohol (PGA), cis‐2‐butene‐1,4‐diol (CBED), and 2‐butyne‐1,4‐diol (BYD). They were undertaken for well‐characterized Pt(111) electrode surfaces which were either annealed in an ultrahigh vacuum (UHV) or electrochemically cycled, as well as for annealed (UHV) Pt(poly). Electrochemical oxidation of BZA, AA, PGA, CBED, and BYD in aqueous fluoride electrolyte proceeds in two stages: first the alcohol moiety is oxidized to CO2 (0.4 V), followed by oxidation of the resulting adsorbed hydrocarbon (alkene, alkyne, or phenyl, 1.0 V); 4PC is relatively inert. The alcohol moiety in 4PC, which is located opposite the pyridine ring from the surface, does not undergo oxidation at an appreciable rate. in fact, 4PC effectively passivates the surface and poisons the electrochemical activity. Electrochemical cycling of the annealed Pt(111) single‐crystal surface greatly increases the oxidation rates of the aliphatic alcohols and, to a lesser extent, increases the oxidation rate of BZA. The oxidation rate enhancement is somewhat smaller if the electrode is electrochemically cycled in the presence of the alcohol. The majority of the difference effected by cycling can be observed after only one cycle. Voltammetry on polycrystalline Pt surfaces resembles that on cycled Pt(111) surfaces for PGA and AA, but resembles that on cycled Pt(111) surfaces for PGA and AA, but resembles that on annealed Pt(111) more closely for the diols CBED and BYD.
Glucose enzyme electrode preparation by the codeposition of platinum and glucose oxidase onto glassy carbon
Authors: Gunasingham Hari , Tan Chee‐Beng
Published: February 2006

A glucose enzyme electrode was fabricated by the simultaneous electrodeposition of enxyme and platinum particles onto a glassy carbon substrate. The electrode combines the electrocatalytic activity of platinum and the stability of glassy carbon. The application of the electrode in flow‐injection detection of glucose is shown. A wide linear range and good precision is possible.
The use of chemisorbed electrocatalytic polymers for detection in flowing solutions
Authors: Barisci Jose N. , Wallace Gordon G. , Wilke Ellen A. , Meaney Mary , Smyth Malcolm R. , Vos Johannes G.
Published: February 2006

The use of a chemically modified electrode for amperometric detection in flowing solutions is described. The modifier is a ruthenium‐containing polymer ([Ru(bpy)2(PVP)5Cl]Cl) that exhibits electro‐catalytic properties. The polymer‐coated electrodes are less prone to fouling (product adsorption) problems and show enhanced sensitivity for various dithiocarbamate metal complexes and nitrite ions. Limitations of the chemisorbed polymer coatings are discussed.
Chemically modified carbon paste and carbon composite electrodes
Authors: Stará Věra , Kopanica Miloslav
Published: February 2006

Carbon paste electrodes and composite carbon electrodes modified by 20% silica gel (30 μm) within the electrode material exhibit many properties typical of a strand of carbon fiber microelectrodes in voltammetric measurements. Charged and uncharged species were studied on these electrodes; phenol, ferricyanide, and potassium ethylxanthogenate yield sigmoidal voltammograms with limiting currents that are virtually independent of the supporting electrolyte concentration. Phenol can be determined in the absence of the electrolyte in water containing up to 30% acetonitrile. Modified carbon composite electrodes are suitable for the determination of potassium ethylxanthogenate for the purposes of controlling flotation processes.
Electrochemical behavior of spiroplatin at carbon paste and platinum electrodes
Authors: Mebsout F. , Kauffmann J.‐M. , Patriarche G. J. , Vereecken J. , Christian G. D.
Published: February 2006

The voltammetric behavior of the hydrolyzed platinum(II) antitumor drug spiroplatin has been investigated at carbon paste and platinized platinum electrodes. The compound is oxidized to the corresponding platinum(IV) species at positive potentials near the solvent oxidation potential. On reversal of the potential scan, two 2‐electron reduction steps occur on the carbon paste electrode, resulting in formation of platinum metal, as confirmed by scanning electron microscopy. In the presence of chloride, different reduction peaks associated with the formation of chloro structures are observed. These depend on the chloride ion concentration. The oxidation‐reduction steps become more reversible at the platinum electrode. The nature of the oxidized species and the amount of platinum deposit were found to be related to the concentration of free chloride ions. Because the carbon paste electrode has the ability to differentiate the different oxidized forms upon reduction, its use is recommended for studying these compounds.
Automated potentiometric end point determination in the Lane‐Eynon titration of reducing sugars
Authors: Alexander Peter W. , Hartati Rahayu D. , Curtin John
Published: February 2006

An instrumental method which closely matches the Lane‐Eynon titration is evaluated with microcomputer interfacing for determining reducing sugars by titration into boiling Fehling's solution. Titrations using copper or platinum as indicator electrodes for end point detection gave millivolt changes at the end point, varying from 18 to 220 mV depending on the electrode couple used, and relative standard deviations of 0.44–0.67% for the precision of measured end, point volumes. Titration data measured with a copper‐platinum electrode couple are acquired in real time for 58 raw sugar samples with reducing sugar content varying from 0.10 to 0.61%. Linear regression correlation of the potentiometric titration data and the standard Lane‐Eynon method gives a correlation coefficient of 0.9960.
Electroanalytical study of indomethacin
Authors: Arcos Julia , López‐Palacios Jesús , Sánchez‐Batanero Pedro
Published: February 2006

The Polarographic behavior of indomethacin has been studied with the aim of developing a procedure for its determination in pharmaceutical tablets. In the study of the electrode process, linear‐sweep voltammetry and controlled potential coulometry were also considered. The electrode reactions are shown to be strongly affected by variations in pH. Adsorption phenomena appear at certain pH values. Detection limits and sensitivity in the determination of indomethacin were obtained by using tast polarography (TP), differential pulse polarography (DPP), and pseudoderivative pulse polarography (NPP).
Analytical applications of metallized membrane electrodes
Authors: Opekar František
Published: February 2006

A survey of the analytical applications of metallized membrane electrodes with both porous and nonporous membranes is presented with emphasis on the methods for determining substances in solution that can be transferred to the gas phase and, thus, determined by the membrane electrode (pneumatoamperometry and pneumatopotentiometry). In this way, a high sensitivity of determination and considerable selectivity can be attained.
An enzyme‐amplified electrochemical immunoassay for thyrotropin
Authors: Cardosi Marco F. , Birch Stephen W. , Smith Brian M. , Johannsson Axel
Published: February 2006

An enzyme‐amplified, two‐site immunoassay utilizing electrochemical detection has been developed for thyrotropin. The lower detection limit of the assay (mean plus 2 standard deviations of the zero standard) is 0.046 ml. U/L, and the precision is good, giving a working range of 0.2 to 18.5 ml. U/L (determined as a percentage dose CV < 10). The assay of a 25 μL serum sample in an eight‐well microtitre strip takes approximately 1 hour. The electrochemical detection is carried out in situ using a custom‐built electrode array comprising eight graphite indicator electrodes and eight stainless‐steel cathodes. This arrangement, together with a fast multiplexer, allows the quasisimultaneous measurement of eight samples. A good correlation between this method and a radioimmunometric assay (IRMA) procedure was obtained for the determination of thyroid‐stimulating hormone (TSH) in patient samples. The relevant properties of a novel graphite material developed for this work are described.