{"title":"Raman Microscopy and Imaging","authors":"G. Steiner","doi":"10.1002/9780470027318.A6404.PUB2","DOIUrl":"https://doi.org/10.1002/9780470027318.A6404.PUB2","url":null,"abstract":"","PeriodicalId":119970,"journal":{"name":"Encyclopedia of Analytical Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126325213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Gradient Elution Chromatography","authors":"J. Dolan, L. Snyder","doi":"10.1002/9780470027318.A5907.PUB2","DOIUrl":"https://doi.org/10.1002/9780470027318.A5907.PUB2","url":null,"abstract":"Elution chromatography can be carried out in either isocratic or gradient modes. In isocratic elution, the mobile-phase composition is held constant during separation of the sample, e.g. 60% v acetonitrile–water. In gradient elution, the mobile-phase composition will be varied during sample separation, e.g. changing from 0 to 100% v acetonitrile–water. Gradient elution requires special chromatographic equipment, as well as somewhat greater care on the part of the operator, but it has important advantages for many separations. Thus, in isocratic elution (Figure 1a), sample peaks tend to “bunch up” at the beginning of the chromatogram (often with decreased resolution) and to broaden at the end of the chromatogram (with reduced detection sensitivity). Gradient elution (Figure 1b), on the other hand, provides a more even spacing of peaks, similar widths throughout the chromatogram, and often a shorter run time. For these and other reasons, gradient elution is preferred for the separation of many samples.","PeriodicalId":119970,"journal":{"name":"Encyclopedia of Analytical Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128385726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Infrared Spectroscopy of Biological Applications: An Overview","authors":"B. Stuart","doi":"10.1002/9780470027318.A0208.PUB2","DOIUrl":"https://doi.org/10.1002/9780470027318.A0208.PUB2","url":null,"abstract":"Infrared spectroscopy has proved to be a powerful tool for the study of biological molecules, including proteins, lipids, carbohydrates, and nucleic acids. This spectroscopic approach enables such molecules to be identified and changes to their chemical structures to be characterized. The application of this technique to biological problems is continually expanding, particularly with the advent of increasingly sophisticated sampling techniques associated with Fourier transform infrared (FTIR) spectroscopy. Biological systems, including animal and plant tissues, microbial cells, clinical samples, and food, have all been successfully studied using infrared spectroscopy. In particular, recent decades have seen a rapid expansion in the number of studies of more complex systems, such as diseased tissues. This article reviews the sampling methods available for biological molecules. The interpretation of infrared data, both qualitatively and quantitatively, for such systems is covered. The specific information to be obtained from the main types of biological molecules is detailed, and the application of biological infrared spectroscopy is reviewed.","PeriodicalId":119970,"journal":{"name":"Encyclopedia of Analytical Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129766242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Verification of Chemicals Related to the Chemical Weapons Convention","authors":"P. Vanninen","doi":"10.1002/9780470027318.A0401.PUB3","DOIUrl":"https://doi.org/10.1002/9780470027318.A0401.PUB3","url":null,"abstract":"This article gives a short historical review of the Chemical Weapons Convention (CWC), discusses the tasks of the Organisation for the Prohibition of Chemical Weapons (OPCW) related to chemical analysis, and lists the chemicals scheduled in the CWC. The Recommended Operating Procedures (ROPs) proposed originally by Finland and subsequently developed further in international cooperation as well as the work instructions (WIs) of the OPCW are briefly discussed. Strategy for analysis of CWC-related chemicals in an off-site laboratory is presented. The international interlaboratory comparison (round-robin) and proficiency tests as well as future prospects are discussed.","PeriodicalId":119970,"journal":{"name":"Encyclopedia of Analytical Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127031950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mass Spectrometry Applications in Forensic Science","authors":"Darrin L. Smith","doi":"10.1002/9780470027318.A9121","DOIUrl":"https://doi.org/10.1002/9780470027318.A9121","url":null,"abstract":"The role of mass spectrometry (MS) in forensic science can be characterized as either molecular or elemental analysis. Relatively small, volatile, nonpolar molecules found in a variety of forensic samples can be analyzed with electron and chemical ionization (CI) routinely coupled with single-stage mass analyzers that provide molecular weight and structural information. Nonvolatile and polar molecules including drugs, poisons, and/or their metabolites routinely found in biological matrices along with other analytes of forensic interest can be determined using electrospray or related soft ionization techniques coupled to tandem mass analyzer systems to identify a molecule through structure elucidation and provide excellent screening and quantitative results. New ambient ionization sources now allow the direct analysis of molecules from a forensic sample surface, with minimal prior preparation or separation. In addition, the sequencing of deoxyribonucleic acid (DNA) has also been difficult with most ionization sources until matrix-assisted laser desorption ionization (MALDI), which has the potential to provide quick and dependable results, was utilized. Elemental profiles also provide reliable methods for characterizing and distinguishing forensic samples. This article aims at providing information about MS and its uses in the field of forensic science. \u0000 \u0000 \u0000Keywords: \u0000 \u0000forensic science; \u0000gas chromatography mass spectrometry (GC/MS); \u0000liquid chromatography mass spectrometry (LC/MS); \u0000ambient ionization; \u0000matrix-assisted laser desorption ionization (MALDI); \u0000elemental mass spectrometry","PeriodicalId":119970,"journal":{"name":"Encyclopedia of Analytical Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122310514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Noble Metals, Analytical Chemistry of","authors":"M. Balcerzak","doi":"10.1002/9780470027318.A2411","DOIUrl":"https://doi.org/10.1002/9780470027318.A2411","url":null,"abstract":"Analytical methods for the determination of noble (precious) metals: ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt) and gold (Au) are presented in this article. Discovery, natural occurrence and main applications of the metals are described. Physical and chemical properties of noble metals are summarized. \u0000 \u0000 \u0000 \u0000The nobility and catalytic activity of precious metals are the main properties that allow their use in a wide variety of applications, e.g. as catalysts in various chemical processes, as autocatalysts, in the electrical and electronic industry and in jewellery. Recent applications of some platinumcompounds (cisplatin and its derivatives) as anticancer drugs are important. \u0000 \u0000 \u0000 \u0000The large variety of complex matrices, wide analytical concentration range (from sub-ppb to >99.99%), low reactivity towards single chemical reagents, great chemical similarities (especially between the pairs Ru and Os, Rh and Ir, Pt and Pd), complexity of platinum group metals (PGMs) species in solutions and rates of reaction make the accurate determination of noble metals a difficult analytical problem. The use of direct instrumental methods is restricted owing to interferences caused by matrix elements and low analyte concentrations. Sampling, sample decomposition, separation and preconcentration are critical steps in the majority of analytical procedures used. \u0000 \u0000 \u0000 \u0000The choice of the digestion procedure used depends on the nature of the sample matrix and the analyte concentration. Fire assay (lead, iron, copper, nickel, tin or nickel sulfide as collectors), oxidizing fusion, acids treatment and chlorination are used to digest various materials. Precipitation, solvent extraction and chromatographic methods (ion-exchange and chelating resins, capillary electrophoresis) are applied to separate noble metals from associated base metals and to separate the individual precious metals. Preliminary isolation of ruthenium and osmium from the other noble and base metals, as well as from each other, by distillation or extraction in the form of RuO4 and OsO4, is often applied. \u0000 \u0000 \u0000 \u0000Spectrophotometric methods using the complexes with inorganic and organic reagents can be applied to the determination of precious metals at ppm levels. Atomic absorption spectroscopy (AAS) (flame and graphite furnace) is well suited to the determination of Au, Pd, Rh and Pt (ppm and ppb levels, respectively). Ultratraces (ppb and sub-ppb levels) of noble metals can be determined in a large number of complex matrices by inductively coupled plasma mass spectrometry (ICPMS) with or without separation and preconcentration steps. A wide range of PGM concentrations, from percentage to ppm levels, can be determined by X-ray fluorescence (XRF) directly in solid samples or after pretreatment procedures (fire assay, coprecipitation, chromatographic preconcentration). Nuclear techniques (mainly neutron activation) are favored for the determination of low (ppb and","PeriodicalId":119970,"journal":{"name":"Encyclopedia of Analytical Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124358980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Gas Chromatography in Analysis of Polymers and Rubbers","authors":"M. Hakkarainen, S. Karlsson","doi":"10.1002/9780470027318.A2010","DOIUrl":"https://doi.org/10.1002/9780470027318.A2010","url":null,"abstract":"This chapter gives an overview of gas chromatography (with mass spectrometry) (GC/MS) of polymers and rubbers. Gas Chromatography (GC) analyzes volatile organic compounds, with an upper limit of 350°C, which means that the compounds to be analyzed must be volatile below this temperature. The technique is able to analyze small quantities of material, which means that it is applicable for example to residual monomers, initiators, catalysts, some additives and degradation products of polymers. It is generally not suitable for analysis of organic compounds at high molecular weight or of low volatility. Care must be taken not to analyze reactive species, which may ruin columns or other parts of the equipment. Proper sample preparation is necessary before GC/MS. Sensitive and selective techniques are used to separate and extract low-molecular-weight organic compounds from polymers. The sample preparation–extraction techniques may be grouped into (1) solvent extraction from solid matrices, (2) solvent extraction of organic compounds from aqueous solutions containing polymer (e.g. biomedical implants in physiological buffers) and (3) solvent-free extraction methods. An ideal extraction method is quantitative, selective, rapid and uses little or no solvent. \u0000 \u0000 \u0000 \u0000Soxhlet is the old and traditional method for solvent extraction from solid sample matrices. Soxhlet is, however, time-consuming (two or three days is not uncommon), nonselective, uses large volumes of solvents and is often not quantitative. Ultrasonication and microwave-assisted extraction (MAE) are instead much more effective. Ultrasonication works by agitating the solution and producing cavitation in the liquid. The technique is useful for example to extract antioxidants from polyethylene (PE). MAE, extracts (semi)volatiles from solid matrices and has been successfully used to extract additives from polyolefins, aroma and flavor compounds from recycled polymers, and oligomers from poly(ethylene terephthalate) (PET). Solvent extractions from aqueous solutions are liquid–liquid extraction (LLE) and solid-phase extraction (SPE). LLE is rapid, but lacks in selectivity, is labor intensive and uses large volumes of organic solvents. SPE is instead suitable for separating volatile and semivolatile compounds and is a physical extraction process involving liquid and a solid phase (sorbent). Examples of separations are degradation products of PE and hydroxyacids in buffer solutions. \u0000 \u0000 \u0000 \u0000Solvent-free extraction methods are headspace gas chromatography (HS/GC), solid-phase microextraction (SPME) and supercritical fluid extraction (SFE). HS/GC determines volatile compounds in liquids and solids. SPME is an inexpensive, rapid and solvent-free technique with applications reported for air samples, water and soil, based on 1-cm long, thin fused silica fiber coated with a polymeric stationary phase mounted in a modified syringe. The stationary phase is available in four different kinds. SFE uses a supercrit","PeriodicalId":119970,"journal":{"name":"Encyclopedia of Analytical Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117154524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Photoacoustic Spectroscopy in Trace Gas Monitoring","authors":"F. Harren, J. Mandon, S. Cristescu","doi":"10.1002/9780470027318.A0718","DOIUrl":"https://doi.org/10.1002/9780470027318.A0718","url":null,"abstract":"Gas phase spectroscopy is nowadays very common in a wide variety of fields next to chemistry and physics. From research involving living organisms to air pollution monitoring, spectroscopic gas sensors have proven to be indispensable tools. There are various ways of utilizing gas sensors, and each application has different demands. Some applications require a very high sensitivity for one specific gas compound, while others benefit more from sensors able to measure a wide range of gases. A high time resolution is also desirable, as well as selectivity, robustness, and little or no need for sample preparation. This paper discusses photoacoustic spectroscopy as a sensitive, on-line and non-invasive tool to monitor the concentration of trace gases. After a short introduction and a historic overview, attention is focused onto the description of devices and equipment; they determine the detection limits and selectivity. Applications are discussed with emphasis on environmental monitoring, medical applications and biological applications (such as post-harvest physiology, plant physiology, microbiology, and entomology).","PeriodicalId":119970,"journal":{"name":"Encyclopedia of Analytical Chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124158859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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