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Analytical Purposes (analytical + purpose)
Selected AbstractsBatch Injection Analysis: An Almost Unexplored Powerful ToolELECTROANALYSIS, Issue 7 2004Maria Abstract The main purpose of this review is to report the development and potentialities of batch injection analysis (BIA) and call the attention of researchers about the power of this (until now) almost unexplored tool. The text focuses on the concepts and potentialities of BIA combined with other techniques for analytical purposes. The association of BIA with amperometry, potentiometry, voltammetry, calorimetry, fluorescence and spectrophotometry is presented and important aspects related with each technique are discussed. Some aspects comparing the similarities and differences between BIA, FIA and wall-jet are presented along the text. [source] Amalgam Electrodes for ElectroanalysisELECTROANALYSIS, Issue 8 2003Øyvind Mikkelsen Abstract Liquid mercury is a unique material for the indicator electrode in voltammetry. One reason for this is the high overvoltage for hydrogen formation, thus extending the actual potential window. Diluted amalgams are important reaction products in voltammetric (polarographic) processes, however liquid amalgams are rarely used directly as electrode material for analytical purposes. Because of the fact that voltammetry is very suitable for field and remote monitoring, issues concerning the use of mercury electrodes in environmental analyses have led to considerable research effort aimed at finding alternative tools with acceptable performance. Solid electrodes are such alternatives. Different types of electrodes are reviewed. In particular, solid amalgam electrodes are very promising, with acceptable low toxicity to be used for field measurements. Solid amalgam electrodes are easy and cheap to construct and are stable over a reasonable time up to several weeks. Assessment of the toxicity risk and the long time stability for remote and unattended monitoring is discussed. The differences between solid dental amalgam electrodes, made by using techniques known from dental clinical practice, and mercury film or mercury layer electrodes on solid substrates are reviewed. In particular the dental technique for constructing solid amalgam electrodes gives advantage because it's fast and inexpensive. Also the technique for making dental amalgam has been explored and optimized over years by dentists, giving advantage when the same technique is used for constructing electrodes. Dental amalgam electrodes has been found to act similar to a silver electrodes, but with high overvoltage towards hydrogen. This make it possible to use the dental amalgam electrode for detection of zinc, cobalt and nickel in additions to other metals like lead, copper, thallium, cadmium, bismuth, iron etc. Also the use for reducible organic compounds is expected to be promising. [source] Cover Picture: Electrophoresis 22'2008ELECTROPHORESIS, Issue 22 2008Article first published online: 26 NOV 200 Regular issues provide a wide range of research and review articles covering all aspects of electrophoresis. Here you will find cutting-edge articles on methods and theory, instrumentation, nucleic acids, CE and CEC, miniaturization and microfluidics, proteomics and two-dimensional electrophoresis. Selected topics of issue 22 are: Microfluidics: Applications for analytical purposes in chemistry and biochemistry ((http://doi.wiley.com/10.1002/elps.200800121)) Simultaneous laser-induced fluorescence and retro-reflected beam interference detection for CE ((http://doi.wiley.com/10.1002/elps.200800292)) Quantitative Proteomics by Fluorescent Labeling of Cysteine Residues using a Set of Two Cyanine-based or Three Rhodamine-based Dyes ((http://doi.wiley.com/10.1002/elps.200800092)) Chemometric resolution of fully overlapped capillary electrophoresis peaks: quantitation of carbamazepine in human serum in the presence of several interferences ((http://doi.wiley.com/10.1002/elps.200800400)) Identification of inorganic ions in post-blast explosive residues using portable capillary electrophoresis instrumentation and capacitively-coupled contactless conductivity detection ((http://doi.wiley.com/10.1002/elps.200800226)) [source] Poly(methylmethacrylate) and Topas capillary electrophoresis microchip performance with electrochemical detectionELECTROPHORESIS, Issue 16 2005Mario Castaño-Álvarez Abstract A capillary electrophoresis (CE) microchip made of a new and promising polymeric material: Topas (thermoplastic olefin polymer of amorphous structure), a cyclic olefin copolymer with high chemical resistance, has been tested for the first time with analytical purposes, employing an electrochemical detection. A simple end-channel platinum amperometric detector has been designed, checked, and optimized in a poly-(methylmethacrylate) (PMMA) CE microchip. The end-channel design is based on a platinum wire manually aligned at the exit of the separation channel. This is a simple and durable detection in which the working electrode is not pretreated. H2O2 was employed as model analyte to study the performance of the PMMA microchip and the detector. Factors influencing migration and detection processes were examined and optimized. Separation of H2O2 and L -ascorbic acid (AsA) was developed in order to evaluate the efficiency of microchips using different buffer systems. This detection has been checked for the first time with a microchip made of Topas, obtaining a good linear relationship for mixtures of H2O2 and AsA in different buffers. [source] Measuring Hospital Care from the Patients' Perspective: An Overview of the CAHPS® Hospital Survey Development ProcessHEALTH SERVICES RESEARCH, Issue 6p2 2005Elizabeth Goldstein Objective. To describe the developmental process for the CAHPS® Hospital Survey. Study Design. A pilot was conducted in three states with 19,720 hospital discharges. Methods of Analysis. A rigorous, multi-step process was used to develop the CAHPS Hospital Survey. It included a public call for measures, multiple Federal Register notices soliciting public input, a review of the relevant literature, meetings with hospitals, consumers and survey vendors, cognitive interviews with consumer, a large-scale pilot test in three states and consumer testing and numerous small-scale field tests. Findings. The current version of the CAHPS Hospital Survey has survey items in seven domains, two overall ratings of the hospital and five items used for adjusting for the mix of patients across hospitals and for analytical purposes. Conclusions. The CAHPS Hospital Survey is a core set of questions that can be administered as a stand-alone questionnaire or combined with a broader set of hospital specific items. [source] World Vision case study of Sigma, an analysis tool based on the Alterian database engineINTERNATIONAL JOURNAL OF NONPROFIT & VOLUNTARY SECTOR MARKETING, Issue 4 2001Scott Logie One of the major issues charities have been concerned with for many years is the inability to access donor records for marketing analysis purposes,donor information has literally been locked up. Charity database tools such as Raiser's Edge and Alms have been built to provide donor details on a record-by-record basis rather than to provide summary information across the entire base. These tools carry out this function very well and have the added benefit of providing data to call centre staff as they make or receive calls from donors. As each charity has to compete more intensely for their share of donor value, however, more detailed behavioural analysis of donor bases is required. To do this, access to the entire donor data is essential, not one record at a time, but structured in a way that allows ad hoc querying. This paper discusses the various technologies that can be used to access donor data for analytical purposes and explains the merits of a new database engine developed by Alterian that allows easy and fast access to many records across multiple data tables. It also shows how one organisation has used the engine to develop a bespoke analysis tool for the charity sector and how a leading relief and development agency, World Vision, is using this tool. Copyright © 2001 Henry Stewart Publications [source] SUBCRITICAL WATER EXTRACTION OF CAFFEINE FROM BLACK TEA LEAF OF IRANJOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2008ANVAR SHALMASHI ABSTRACT This study examines subcritical water extraction (SCWE) of caffeine from black tea leaf. The effects of various operating conditions such as water temperature (100, 125, 150 and 175C), water flow rate (1, 2 and 4 g/min), mean particle size (0.5, 1 and 2 mm) on extraction yield and rate were determined. SCWE at 175C, water flow rate of 2 g/min and mean particle size of 0.5 mm were found to be able to recover 3.82% (w/w) of caffeine present in the black tea leaf within 3 h of extraction. In comparison to the SCWE, conventional hot water extraction showed 3.30% (w/w) extraction yield. It was found also that pressure had no effect on extraction yield and rate. PRACTICAL APPLICATIONS Recently, subcritical water has become of great interest as an alternative solvent for extraction of natural active compounds. Subcritical water, as a green solvent, can be used in many different fields of applications. In recent years, extraction of flavors, fragrances and antioxidant components from plant materials, and hydrolysis of carbohydrates, vegetable oils and fatty acids have been widely investigated by many researchers. Using subcritical water for analytical purposes, for soil remediation and applying it as a reaction media are some other interesting fields for practical applications. Subcritical water is an excellent solvent for caffeine as well as many other organic compounds but is safer than the organic solvents that are used for caffeine extraction. [source] Adjustment and control of SERS activity of metal substrates by pressureJOURNAL OF RAMAN SPECTROSCOPY, Issue 4 2010Lixin Xia Abstract Metal pellets of silver and copper for surface-enhanced Raman scattering (SERS) spectroscopy were prepared by compression with different pressures. It was found that the SERS activity of the pellet could be controlled by pressure. Enhanced Raman scattering properties of the metal pellets in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA) with excitation at 632.8 or 514 nm could be obtained by choosing proper pressure of pellatization. The SERS peak intensity of the band at ,1584 cm,1 of 4-MBA adsorbed on the metal pellets varies as a function of applied pressure, and which is about 1.2,32 times greater than when it is adsorbed on silver and copper particles. The calculated results of three-dimensional finite-difference time-domain method (3D-FDTD) are in good agreement with the experimental data. Moreover, no spurious peaks appear in the SERS spectra of the samples because no other chemicals are involved in the simple preparation process of the metal pellets, which will facilitate its use as an SERS-active substrate for analytical purposes. In summary, SERS-active metal pellets can be produced simply and cost effectively by the method reported here, and this method is expected to be utilized in the development of SERS-based analytical devices. Copyright © 2009 John Wiley & Sons, Ltd. [source] The application of Tet repressor in prokaryotic gene regulation and expressionMICROBIAL BIOTECHNOLOGY, Issue 1 2008Ralph Bertram Summary Inducible gene expression based upon Tet repressor (tet regulation) is a broadly applied tool in molecular genetics. In its original environment, Tet repressor (TetR) negatively controls tetracycline (tc) resistance in bacteria. In the presence of tc, TetR is induced and detaches from its cognate DNA sequence tetO, so that a tc antiporter protein is expressed. In this article, we provide a comprehensive overview about tet regulation in bacteria and illustrate the parameters of different regulatory architectures. While some of these set-ups rely on natural tet -control regions like those found on transposon Tn10, highly efficient variations of this system have recently been adapted to different Gram-negative and Gram-positive bacteria. Novel tet -controllable artificial or hybrid promoters were employed for target gene expression. They are controlled by regulators expressed at different levels either in a constitutive or in an autoregulated manner. The resulting tet systems have been used for various purposes. We discuss integrative elements vested with tc-sensitive promoters, as well as tet regulation in Gram-negative and Gram-positive bacteria for analytical purposes and for protein overproduction. Also the use of TetR as an in vivo biosensor for tetracyclines or as a regulatory device in synthetic biology constructs is outlined. Technical specifications underlying different regulatory set-ups are highlighted, and finally recent developments concerning variations of TetR are presented, which may expand the use of prokaryotic tet systems in the future. [source] | |||||||||||||