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Analytical Applications (analytical + application)
Selected AbstractsSecond-order Scattering and Frequency Doubling Scattering Spectra of Thallium(III)-Methotrexate System and Its Analytical ApplicationCHINESE JOURNAL OF CHEMISTRY, Issue 9 2008Cun-Xian XI Abstract In pH 4.9 Britton-Robinson buffer solution, methotrexate (MTX) reacted with thallium(III) to form a 3:1 chelate. This resulted in great enhancement of second-order scattering (SOS) spectra and frequency doubling scattering (FDS) spectra and appearance of new SOS and FDS spectra. Their maximum wavelengths were located at 520 and 390 nm, respectively. The increments of scattering intensities (,I) were directly proportional to the concentrations of MTX in the ranges of 0.022,2.0 µg·mL,1 (SOS method) and 0.008,2.5 µg·mL,1 (FDS method). The methods exhibited high sensitivities. The detection limits for MTX were 7.4 ng·mL,1 (SOS method) and 2.3 ng·mL,1 (FDS method), respectively. The optimum conditions of the reaction, the influencing factors and the effects of coexisting substances were investigated. A highly sensitive, simple and fast method for the determination of MTX has been developed. The method can be applied satisfactorily to the determination of MTX in human serum samples. In this work, the charge distribution of MTX was calculated by a CNDO quantum chemistry method. In addition, the reaction mechanism was discussed. [source] Effects of the Interaction of Rifamycin SV with Serum Albumins on the Resonance Rayleigh Scattering Spectra and Their Analytical ApplicationCHINESE JOURNAL OF CHEMISTRY, Issue 5 2008Ji-Dong YANG Abstract In pH 4.5,4.8 Britton-Robinson buffer solution, rifamycin SV (i.e. rifamycin sodium) can react with serum albumin such as human serum albumin (HSA) and bovine serum albumin (BSA) to form macromolecular complexes by electrostatic attraction and hydrophobic force. As a result, the resonance Rayleigh scattering (RRS) of the drug was enhanced remarkably and the RRS peaks were at 374 and 552 nm. The enhancement of RRS (,I) is directly proportional to the concentration of HSA or BSA. The linear ranges and the detection limits are 0.03,6.0 µg/mL and 9.0 ng/mL for HSA, and 0.01,8.0 µg/mL and 2.0 ng/mL for BSA, respectively. In this work, a sensitive, selective, simple and fast method for the determination of trace amounts of serum albumin by RRS technique has been developed, which was applied to the determination of serum albumin in the synthesized samples and human urine samples with satisfactory results. [source] Investigation of Chemiluminescence with Electrogenerated Reagents and Its Analytical ApplicationCHINESE JOURNAL OF CHEMISTRY, Issue 11 2003Zhu-Jup Zhang Abstract In this paper, studies on chemiluminescence (CL) systems with electrogenerated reagents, including BrO,, CIO,, Br2, [Cu-(HIO6)2]5- , H2O2, Mn3+, Co3+ and Ag2+, are described. The analytical applications of the CL system with electrogenerated reagents are reviewed. [source] Preparation, Characterization and Analytical Applications of a New and Novel Electrically Conducting PolymerELECTROANALYSIS, Issue 15 2006F. D'Eramo Abstract In this study, a glassy carbon electrode (GC) was modified with an electropolymerized film of 1-naphthylamine (1-NAP) with a subsequent overoxidation treatment in 0.2,M sodium hydroxide solution. This polymer p-1-NAPox film coated GC electrode was used for the selective determination of dopamine (DA) in the presence of a triple concentration of ascorbic acid (AA). These studies were performed using cyclic voltammetry and square-wave voltammetry at physiological pH. p-1-NAPox shows an attractive permselectivity, a marked enhancement of the current response and antifouling properties when compared to a bare GC electrode activated in basic media. With a preconcentration time of 3,minutes at open circuit, linear calibration plots were obtained for DA in buffer solution (pH,7.4) over the concentration range from 1×10,6,1×10,4 M with a detection limit of 1.59×10,7 M. [source] The Electrochemical Oxidation of N,N -Diethyl- p -Phenylenediamine in DMF and Analytical Applications.ELECTROANALYSIS, Issue 11 2003Part I: Mechanistic Study Abstract The electrochemical oxidation of N,N -diethyl- p -phenylenediamine in dimethylformamide has been studied at platinum and gold microdisk electrodes of various radii between 6.7 and 66,,m. The voltammetric responses revealed two electrochemically reversible waves the second of which becomes larger at higher concentrations and bigger electrode radii. The voltammetric signals have been modelled and the electrochemical oxidation reaction is not inconsistent with an ECrevECE reaction. Kinetic parameters are reported. [source] "Nanoions": Fundamental Properties and Analytical Applications of Charged NanoparticlesCHEMPHYSCHEM, Issue 15 2007Kyle J. M. Bishop Abstract Mixtures of oppositely charged nanoparticles (NPs) precipitate sharply only at the point of NP electroneutrality. This behavior,reminiscent of the threshold precipitation of inorganic ions,is specific to the nanoscale and can be attributed to the formation of like-charged NP clusters stabilized in solution by mutual electrostatic repulsions. NP titrations based on this phenomenon provide a uniquely accurate tool for measuring charges tethered onto nanoscopic objects and for studying the thermodynamics of surface reactions at the nanoscale. [source] Resonance Rayleigh Scattering Spectra of Thorium (IV)-bisazo Dye of Chromotropic Acid-protein Systems and Their Analytical ApplicationsCHINESE JOURNAL OF CHEMISTRY, Issue 1 2003U Fan Abstract In acidic medium, thorium (IV) can react with a bisazo dye of chromotropic adds such as arsenazo HI (AA in), arsenazo M (AA M), chlorophosphonazo III (CPA III) and chlorosulphonphenol S (CSP S) to form an anionic chelate which further interacts with some proteins to produce a complex. This results in a significant enhancement of intensity of the resonance Rayleigh scattering (RRS) and the appearance of a new RRS spectrum. There are a few obvious RRS peaks in the range of 400,470 nm and the most intensive peak of them is located at 470 nm. The intensity of RRS is directly proportional to the concentration of protein in the range of 0,l.ö,g-mL,1 for Th(IV)-CPA III system, 0,2.8 ,g-mL,1 for Th(IV)-AA M system, 0,2.0 ,g·mL,1 for Th(IV)-AA III system and 0,0.28 ,g·mL,1 for Th(IV)-CSP S system, respectively. The detection limits for BSA (3s,) are 10.7 ng·mL,1 for Th (IV)-CPA III, 6.3 ng·mL,1 for Th(IV)-CSP S, 13.6 ng·mL,1 for Th(IV)-AA III and 22.1 ng·mL,1 for Th(IV)-AA M, respectively. This new RRS method has high sensitivity and fairly good selectivity and can be applied to the direct determination of proteins in human serum with satisfactory results. [source] Silver Amalgam Film Electrode of Prolonged Application in Stripping ChronopotentiometryELECTROANALYSIS, Issue 18 2007Kapturski Abstract The utility of the cylindrical silver-based mercury film electrode of prolonged analytical application in stripping chronopotentiometry (SCP) was examined. This electrode allowed us to obtain good reproducibility of results owing to the special electrode design, which enables regeneration of the thin layer before each measurement cycle. The accessible potential window in KNO3 (pH,2), acetate and ammonia buffers was defined, and the optimal conditions (i.e., stripping current, deposition potential and deposition time) for the determination of Cd and Pb traces were selected. The detection limits, obtained for an accumulation time of 60,s, were 0.023,,g/L for Cd and 0.075,,g/L for Pb. The response increases linearly with Cd, Pb and Zn concentration, up to at least 100,,g/L. It was also shown that the proposed procedure ensures excellent separation of the In and Tl, Pb and Tl or the In and Cd signals. The method was tested with dolomite and lake sediment samples, and good agreement with reference values was achieved. The obtained results showed good reproducibility (RSD=5,6%) and reliability. [source] Barrel Plating Rhodium Electrode: Application to Flow Injection Analysis of HydrazineELECTROANALYSIS, Issue 14 2005Jun-Wei Sue Abstract We introduce here the application of barrel plating technology for mass production of disposable-type electrodes. Easy for mass production, barrel plating rhodium electrode (Rh-BPE) is for the first time demonstrated for analytical application. Hydrazine was chosen as a model analyte to elucidate the electrocatalytic and analytical ability of the Rh-BPE system in pH,7 phosphate buffer solution. Flow injection analysis (FIA) of hydrazine showed a linear calibration range of 25,1000,ppb with a slope and a regression coefficient of 5,nA/ppb and 0.9946, respectively. Twenty-two replicate injections of 25,ppb hydrazine showed a relative standard deviation of 3.17% indicating a detection limit (S/N=3) of 2.5,ppb. The system can be continuously operated for 1 day without any alteration in the FIA signals and is tolerable to the interference of oxalic acid, gelatine, Triton X-100, and albumin for even up to 100 times excess in concentration with respect to 400,ppb hydrazine. Since the fabrication cost of the electrode is cheap, it is thus disposable in nature. Furthermore, barrel plating technique can be extendable to other transition metals for application in many fields of research interest. [source] Simultaneous real-time assay of copper and cadmium ions by infrared photo diode electrode implanted in the muscle of live fishJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 4 2009Suw Young Ly Abstract The electrical circuit of an infrared photodiode electrode (IPE) was used in the simultaneous assay of copper and cadmium ions. The electrode's cyclic voltammetry (CV), chronoamperometry and square-wave (SW) stripping voltammetric optimum conditions were examined. Results for 0,160 mg L,1 and 50,400 ,g L,1 SW Cu(II) Cd(II), the relative standard deviation of 0.158 Cu(II), 0.077 Cd(II) (n = 15) using 20.0 mg L,1 have been obtained at optimum conditions. The low detection limit (S/N) was attained to be at 14.71 ,g L,1(2.31 × 10,7 mol L,1) Cu(II) and 18.42 ,g L,1(1.63 × 10,7 mol L,1) Cd(II). The handmade electrode was implanted deep in the muscle of live fish and interfaced with an electrochemical workstation. Real-time analytical application was performed on the online assay of living tissue as the specimen was moving. The methods are deemed useful in interfaced assay for physiological control, nanodiode fabrication, and in the production of laboratory on a biochip. © 2009 Wiley Periodicals, Inc. J Biochem Mol Toxicol 23:256,262, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20287 [source] Protein purification using chromatography: selection of type, modelling and optimization of operating conditionsJOURNAL OF MOLECULAR RECOGNITION, Issue 2 2009J. A. Asenjo Abstract To achieve a high level of purity in the purification of recombinant proteins for therapeutic or analytical application, it is necessary to use several chromatographic steps. There is a range of techniques available including anion and cation exchange, which can be carried out at different pHs, hydrophobic interaction chromatography, gel filtration and affinity chromatography. In the case of a complex mixture of partially unknown proteins or a clarified cell extract, there are many different routes one can take in order to choose the minimum and most efficient number of purification steps to achieve a desired level of purity (e.g. 98%, 99.5% or 99.9%). This review shows how an initial 'proteomic' characterization of the complex mixture of target protein and protein contaminants can be used to select the most efficient chromatographic separation steps in order to achieve a specific level of purity with a minimum number of steps. The chosen methodology was implemented in a computer- based Expert System. Two algorithms were developed, the first algorithm was used to select the most efficient purification method to separate a protein from its contaminants based on the physicochemical properties of the protein product and the protein contaminants and the second algorithm was used to predict the number and concentration of contaminants after each separation as well as protein product purity. The application of the Expert System approach was experimentally tested and validated with a mixture of four proteins and the experimental validation was also carried out with a supernatant of Bacillus subtilis producing a recombinant , -1,3-glucanase. Once the type of chromatography is chosen, optimization of the operating conditions is essential. Chromatographic elution curves for a three-protein mixture (, -lactoalbumin, ovalbumin and , -lactoglobulin), carried out under different flow rates and ionic strength conditions, were simulated using two different mathematical models. These models were the Plate Model and the more fundamentally based Rate Model. Simulated elution curves were compared with experimental data not used for parameter identification. Deviation between experimental data and the simulated curves using the Plate Model was less than 0.0189 (absorbance units); a slightly higher deviation [0.0252 (absorbance units)] was obtained when the Rate Model was used. In order to optimize operating conditions, a cost function was built that included the effect of the different production stages, namely fermentation, purification and concentration. This cost function was also successfully used for the determination of the fraction of product to be collected (peak cutting) in chromatography. It can be used for protein products with different characteristics and qualities, such as purity and yield, by choosing the appropriate parameters. Copyright © 2008 John Wiley & Sons, Ltd. [source] Gold Nanoparticles in Nonenzymatic Electrochemical Detection of SugarsELECTROANALYSIS, Issue 19-20 2006Fredy Kurniawan Abstract A nonenzymatic electrochemical sensor for detection of sugars was prepared by layer-by-layer deposition of gold nanoparticles on thin gold electrodes. The deposition was optimized by using of surface plasmon resonance. Voltammetric investigation and impedance spectroscopy of the sensor was performed. Electrical currents caused by glucose on bare gold electrodes and on gold electrodes coated by immobilized gold nanoparticles were compared. The electrodes with nanoparticles display much higher current of glucose oxidation. The oxidation becomes blocked when the swept electrode potential exceeded +0.25,V, during the back scan an oxidation peak is observed again but at less positive potential. The magnitudes of these current peaks are linearly dependent on the glucose concentration; this dependence can be used as calibration for analytical applications. The limit of detection for glucose is below 0.5,mM, the sensitivity (normalized to the macroscopic electrode surface) is about 160,,A,cm,2,mM,1. The sensor response is linear till at least 8,mM of glucose concentration. [source] Recent Updates of Chemically Modified Electrodes in Analytical ChemistryELECTROANALYSIS, Issue 13 2003Jyh-Myng Zen Abstract This review article updates recent developments in chemically modified electrodes (CMEs) towards analytical applications for the year of 2000,2002 with 179 references. The broad topics are subdivided into four main categories: i) physisorption/chemisorption, ii) covalently linked, iii) homogenous (uniform) multilayer and iv) heterogeneous (non-uniform) multilayer CMEs. The criteria for the preparation of CMEs in elecrocatalytic systems are clearly described in Section 1. Some of the encouraging results related to Au-nanoparticles for DNA detection and new ceramic carbon, carbon nanotubes, copper-plated screen-printed and Nafion/lead ruthenate pyrochlore CMEs for catalytic application were especially discussed in this review. [source] Clay Modified Electrodes: Present Applications and ProspectsELECTROANALYSIS, Issue 10 2003Zuzana Navrátilová Abstract This review presents the preparation and use of clay modified electrodes with emphasis on analytical applications. Besides, some investigations on ion-exchange and sorption mechanisms are outlined. Expected prospects of clay modified electrodes in the field of electrochemistry are discussed briefly. [source] Simultaneous electrochemical and electrochemiluminescence detection for microchip and conventional capillary electrophoresisELECTROPHORESIS, Issue 3 2005Haibo Qiu Abstract A simultaneous electrochemical (EC) and electrochemiluminescence (ECL) detection scheme was introduced to both microchip and conventional capillary electrophoresis (CE). In this dual detection scheme, tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)32+) was used as an ECL reagent as well as a catalyst (in the formation of Ru(bpy)33+) for the EC detection. In the Ru(bpy)32+ -ECL process, Ru(bpy)33+ was generated and then reacted with analytes resulting in an ECL emission and a great current enhancement in EC detection due to the catalysis of Ru(bpy)33+. The current response and ECL signals were monitored simultaneously. In the experiments, dopamine and three kinds of pharmaceuticals, anisodamine, ofloxacin, and lidocaine, were selected to validate this dual detection strategy. Typically, for the EC detection of dopamine with the presence of Ru(bpy)32+, a ,5 times higher signal-to-noise ratio (S/N) can be achieved than that without Ru(bpy)32+, during the simultaneous EC and ECL detection of a mixture of dopamine and lidocaine using CE separation. The results indicated that this dual EC and ECL detection strategy could provide a simple and convenient detection method for analysis of more kinds of analytes in CE separation than the single EC or ECL detection alone, and more information of analytes could be achieved in analytical applications simultaneously. [source] Near infrared spectroscopy in the development of solid dosage formsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2007Eetu Räsänen The use of near infrared (NIR) spectroscopy has rapidly grown partly due to demands of process analytical applications in the pharmaceutical industry. Furthermore, newest regulatory guidelines have advanced the increase of the use of NIR technologies. The non-destructive and non-invasive nature of measurements makes NIR a powerful tool in characterization of pharmaceutical solids. These benefits among others often make NIR advantageous over traditional analytical methods. However, in addition to NIR, a wide variety of other tools are naturally also available for analysis in pharmaceutical development and manufacturing, and those can often be more suitable for a given application. The versatility and rapidness of NIR will ensure its contribution to increased process understanding, better process control and improved quality of drug products. This review concentrates on the use of NIR spectroscopy from a process research perspective and highlights recent applications in the field. [source] Rapid analysis of food products by means of high speed gas chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2007Paola Donato Abstract Since the invention of GC, there has been an ever increasing interest within the chromatographic community for faster GC methods. This is obviously related to the fact that the number of samples subjected to GC analysis has risen greatly. Nowadays, in routine analytical applications, sample throughput is often the most important aspect considered when choosing an analytical method. Gas chromatographic instrumentation, especially in the last decade, has been subjected to continuous and considerable improvement. High-speed injection systems, electronic gas pressure control, rapid oven heating/cooling and fast detection are currently available in a variety of commercial gas chromatographs. The main consequence of this favourable aspect is that high-speed GC is being increasingly employed for routine analysis in different fields. Furthermore, the employment of dedicated software makes the passage from a conventional to a fast GC method a rather simple step. The present review provides an overview of the employment of fast GC techniques for the analysis of food constituents and contaminants. A brief historical and theoretical background is also provided for the approaches described. [source] Immobilized trypsin systems coupled on-line to separation methods: Recent developments and analytical applicationsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2005Gabriella Massolini Abstract The ability to rapidly and efficiently digest and identify an unknown protein is of great utility for proteome studies. Identification of proteins via peptide mapping is generally accomplished through proteolytic digestion with enzymes such as trypsin. Limitations of this approach consist in manual sample manipulation steps and extended reaction times for proteolytic digestion. The use of immobilized trypsin for cleavage of proteins is advantageous in comparison with application of its soluble form. Enzymes can be immobilized on different supports and used in flow systems such as immobilized enzyme reactors (IMERs). This review reports applications of immobilized trypsin reactors in which the IMER has been integrated into separation systems such as reversed-phase liquid chromatography or capillary electrophoresis, prior to MS analysis. Immobilization procedures including supports, mode of integration into separation systems, and methods are described. [source] Electrogenerated chemiluminescence of ruthenium complex immobilized in a highly cross-linked polymer and its analytical applicationsLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2008Lihua Shen Abstract Electrogenerated chemiluminescence (ECL) of a ruthenium complex polymer modified carbon paste electrode and its analytical applications were investigated. The ruthenium complex polymer was prepared using bis(2,2-bipyridine) (4,4-dicarboxy-2,2-bipyridine) ruthenium(II). The ECL behaviours of ruthenium complex polymer modified carbon paste electrode were investigated in the absence and presence of tripropylamine (TPA). The modified carbon paste electrode exhibited long-term stability and fine reproducibility. The ECL intensity of the modified carbon paste electrode was linear with the concentration of TPA in the range 2.0 × 10,6,3.8 × 10,3 mol/L, with a detection limit (S:N = 3) of 6 × 10,7 mol/L. It was also found that raceanisodamine could enhance the ECL intensity of the modified electrode. The ECL intensity of the modified carbon paste electrode was linear with the concentration of raceanisodamine in the range 1.1 × 10,5,6.0 × 10,4 mol/L, with a detection limit (S:N = 3) of 6 × 10,6 mol/L. This work demonstrates that the entrapment of ruthenium complex in a highly cross-linked polymer is a promising approach to construct an ECL modified electrode with long-term stability and fine reproducibility. The modified electrode designed has a potential application in the ECL detector. Copyright © 2008 John Wiley & Sons, Ltd. [source] Assessment of the plasma desorption time-of-flight mass spectrometry technique for pesticide adsorption and degradation on ,as-received' treated soil samplesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2005J. P. Thomas The assessment of the plasma desorption time-of-flight mass spectrometry (PD-TOFMS) technique as a tool for direct characterization of pesticides adsorbed on agricultural soil is made for the first time in this study. Pellets of soils impregnated by solutions of three pesticides, namely norflurazon, malathion and oxyfluorfen, as well as deposits of these solutions onto aluminum surfaces, were investigated to this end. The yield values of the most characteristic peaks of the negative ion mass spectra were used to determine both the lowest concentrations detected on soils and limits of detection from thin films. The lowest values on soils are for malathion (1000,ppm range), and the largest for norflurazon (20,000,ppm), which is close to the limit of detection (LOD) found for the pesticide on the aluminum substrate (,0.2,µg,·,cm,2). Different behaviors were observed as a function of time of storage in the ambient atmosphere or under vacuum; norflurazon adsorbed on soil exhibited high stability for a long period of time, and a rapid degradation of malathion with the elapsed time was clearly observed. The behavior of oxyfluorfen was also investigated but segregation processes seem to occur after several days. Although by far less sensitive than conventional methods based on extraction processes and used for real-world analytical applications, this technique is well suited to the study of the transformations occurring at the sample surface. A discussion is presented of the future prospects of such experiments in degradation studies. Copyright © 2005 John Wiley & Sons, Ltd. [source] Lophine derivatives as versatile analytical toolsBIOMEDICAL CHROMATOGRAPHY, Issue 2-3 2003Kenichiro Nakashima Abstract Lophine (2,4,5-triphenylimidazole) derivatives as versatile analytical tools in biomedical sciences are described. Chemiluminescence (CL) and fluorescence (FL) properties of the lophine derivatives are first demonstrated including the CL reaction mechanism, effects of substituents on CL yields, FL spectral behaviors, etc. Next, analytical applications to the determination of metal ions such as cobalt (II) and chromium (VI) are discussed. Finally, the application studies of lophine derivatives as CL and FL reagents for the determination of organic substances in biological materials are presented. Among the derivatives, 2-(4-hydrazinocarbonylphenyl)-4,5-diphenylimidazole (HCPI) and 4-(4,5-diphenyl-1H -imidazol-2-yl)benzoyl chloride (DIB-Cl) are studied, with their excellent properties as labeling reagents for fatty acids and amines and/or phenols, respectively, in high-performance liquid chromatography. The utility of boronic acid derivatives as CL enhancers is also discussed in this review. Copyright © 2003 John Wiley & Sons, Ltd. [source] Toner and paper-based fabrication techniques for microfluidic applicationsELECTROPHORESIS, Issue 15 2010Wendell Karlos Tomazelli Coltro Abstract The interest in low-cost microfluidic platforms as well as emerging microfabrication techniques has increased considerably over the last years. Toner- and paper-based techniques have appeared as two of the most promising platforms for the production of disposable devices for on-chip applications. This review focuses on recent advances in the fabrication techniques and in the analytical/bioanalytical applications of toner and paper-based devices. The discussion is divided in two parts dealing with (i) toner and (ii) paper devices. Examples of miniaturized devices fabricated by using direct-printing or toner transfer masking in polyester-toner, glass, PDMS as well as conductive platforms as recordable compact disks and printed circuit board are presented. The construction and the use of paper-based devices for off-site diagnosis and bioassays are also described to cover this emerging platform for low-cost diagnostics. [source] | ||||||||||