bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Chromatography and Mass Spectrometry in Clinical Chemistry
Authors: Bertholf Roger L. 
Published: September 2006

AbstractAutomated spectrophotometric, electrochemical, and immunochemical analyses have become the mainstays of clinical chemistry and toxicology laboratory services, but their scope is limited. A wide array of clinically relevant analytes demand more sophisticated analytical techniques to provide sensitive and specific assays for diagnostic purposes. Gas chromatography (GC) and mass spectrometry (MS) are becoming cost‐effective alternatives for many of these challenging assays. GC is a robust technique that offers the ability to resolve volatile components of a complex mixture. MS provides structural information that can unambiguously identify a compound. In combination, these two techniques provide qualitative and quantitative answers to many difficult analytical problems. GC and MS applications have been developed for a variety of clinical analytes, and the use of these methods has created new and exciting frontiers for clinical laboratory medicine. Several clinical applications of these analytical techniques will be discussed in this chapter.
Molecular Biological Analyses and Molecular Pathology in Clinical Chemistry
Authors: Lo Y.M. Dennis , Lam Ching‐Wan , Wong Ivy H.N. 
Published: September 2006

AbstractThe recent introduction of powerful methods for the analysis of nucleic acids has started a revolution in medicine, opening up a new field of molecular diagnosis. The core technologies of molecular diagnosis involve techniques for the amplification and characterization of nucleic acids. These techniques have enabled the diagnosis of many diseases with unprecedented sensitivity and specificity. As research tools, these methods have increased our understanding of many diseases on a molecular level, with the unraveling of the molecular pathology of many common disorders. Foundation for the rapid and continual development of molecular pathology into the next century has received a boost from the Human Genome Project (HGP), which is expected to be completed over the next few years and which will provide the essential genetic blueprint for future investigations.
Atomic Spectroscopy in Coatings Analysis
Authors: Weldon Dwight G. 
Published: September 2006

Abstract
In atomic spectroscopy, vaporized neutral atoms are detected by measuring either the absorption or emission of light at characteristic frequencies. In atomic absorption (AA) spectroscopy, radiation is absorbed by the atom in the process of exciting an electron from a lower energy state into a higher energy state. In atomic emission (AE) and inductively coupled plasma (ICP) spectroscopy, radiation is released when an electron from an excited energy state relaxes into a lower energy state. The energy required for these transitions occurs in either the visible or ultraviolet region of the electromagnetic spectrum.
Atomic spectroscopy is a very useful technique in the field of coating analysis. It is primarily used for the analysis of metallic constituents, such as certain pigments and coating additives. It is extremely sensitive, and can detect several dozen different elements. It is especially useful in determining whether or not a particular coating contains environmentally hazardous levels of heavy metals, such as lead, cadmium and chromium. Disadvantages of the technique include its inability to determine the chemical form in which the element is present, somewhat laborious sample preparation procedures, and the inability to determine other important constituents of coatings, such as resins and solvents.
Gas Chromatography in Coatings Analysis
Authors: Haken J.K. 
Published: September 2006

AbstractThis work describes the analysis of coating materials using gas chromatography (GC). An element of volatility is necessary for samples to be amenable to the technique and early applications concerned the analysis of solvents and their mixtures. The examination of low molecular weight and volatile components of coatings followed; these included trace or residual products in resins. The resinous or binder components are essentially nonvolatile, and to be amenable to GC a considerable reduction in molecular weight is necessary. This has been achieved by chemical cleavage of condensation systems, with examination of the reconstituted reactants or their derivatives, or by thermal means in the absence of oxygen where pyrolysis provides fragments which may be related to the initial composition. Chemical cleavage was applied to alkyd resins, acrylics, polysiloxanes, polyurethanes and polyethers during the 1960s and while the results were most satisfactory, the time required was considered excessive. Several decades later, some of the problems have been eliminated but the procedures have found little application. Pyrolysis was also introduced at the same time and while the early reports were of low reproducibility, refinements in technique allow reproducible results to be achieved rapidly. The major area of the application of GC to coating materials is pyrolysis, where, in combination with mass spectroscopy (MS), valuable information is achieved in minutes.Other coating applications of GC include inverse chromatography which has found negligible use and headspace chromatography which is widely used in determining the source of odors or taints in coated food packaging. Special applications of GC include use in forensic science where accelerants used by arsonists are readily detected and also examination and identification of paint flakes by pyrolysis GC/MS. Similarly pyrolysis techniques are used in conservation studies, with the analysis of old paints on art works.
InfraredLIDARApplications in Atmospheric Monitoring
Authors: Orr Brian J. 
Published: September 2006

AbstractThe acronym LIDAR stands for light detection and ranging, an optical analog of RADAR (radio detection and ranging). The conventional version of LIDAR requires a laser transmitter to launch short pulses of coherent light, which are scattered from atmospheric targets of interest back to an optical receiver, with a time delay that is determined by the range of the target. Optical phenomena in the Earth's atmosphere (e.g. Rayleigh scattering, Raman scattering, Mie scattering, refraction, and resonant absorption) contribute to the amplitude of optical signals returning to the receiver and their characteristic wavelength dependence allows us to measure the concentration and velocity distributions of different atmospheric molecules and aerosol particles. LIDAR backscattering in the infrared (IR) region, on which this article concentrates, is well suited to detecting aerosols (as in clouds or industrial particulate emissions). IR DIAL (differential absorption LIDAR), a variant in which two wavelengths are used simultaneously to separate resonant molecular signals from background, enables most molecular species to be monitored by means of their IR absorption spectra. A closely related approach comprises long‐path IR laser absorption, with retro‐reflection from a topographic target (e.g. a strategically located mirror); this sacrifices optical range information but gains sensitivity because it integrates over all molecules in the optical column between the transmitter/receiver and the reflector. Such techniques are vitally dependent on pulsed IR laser technology.
Flame and Graphite Furnace Atomic Absorption Spectrometry in Environmental Analysis
Authors: Sperling Michael 
Published: September 2006

AbstractAtomic absorption spectrometry (AAS) is one of the most often used techniques for the quantitative determination of elements in environmental materials at trace and ultratrace levels. AAS is an optical atomic spectrometric technique based on the measurement of the specific absorption originating from free nonionized atoms in the gas phase. To transfer the analyte to free atoms, different types of atomizer are in use, the flame and the graphite furnace types being the most often used. Typical detection limits of flame atomic absorption spectrometry (FAAS) are of the order of 1–100 µg L−1, making it a perfect tool for the determination of minor and trace elements, at least for contaminated samples. Graphite furnace atomic absorption spectrometry (GFAAS), offering detection limits which are about a factor of 20–200 lower than for FAAS, is the standard method for many trace elements, especially for background values, and for unpolluted samples, such as fresh water and biological materials. AAS in its conventional configuration is a single‐element technique, which has to be used in a sequential mode when more than one element has to be determined. However, there are commercial instruments available that can be used for the determination of 6–8 elements simultaneously.
Hydride Generation Sample Introduction for Spectroscopic Analysis in Environmental Samples
Authors: Narasaki Hisatake 
Published: September 2006

Abstract
The hydride generation (HG) technique using sodium tetrahydroborate(III) (SBH) is applied to atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP/AES), and inductively coupled plasma mass spectrometry (ICP/MS). All the detection limits using the HG technique are less than those for solution nebulization. Chemical speciation in the HG technique is effected by changing the pH of the solution, the cold trap method and various hyphenated techniques. The author used a gas–liquid separator containing a spiral tube to separate efficiently the hydrides from solution. This minimized the consumption of the sample and SBH solutions and of the hydrogen evolution compared with the continuous‐flow method. The author used a high‐resolution ICP/MS instrument which allowed the use of hydrochloric acid in the sample preparation of arsenic and the determination of selenium without its isotopes.
Infrared Spectroscopy in Environmental Analysis
Authors: Visser Tom 
Published: September 2006

Abstract

Infrared (IR) spectroscopy is a universal, versatile analytical technique for the structure elucidation and quantification of a large variety of organic, inorganic and biological samples. The technique is based on the measurement of IR radiation, absorbed or emitted by a sample, as a function of the wavelength in the region 2.5–100 µm, or 4000–100 cm
−1
in wavenumbers. The absorption or emission of IR radiation is related to discrete vibrational and rotational transitions in a molecule and, therefore, represents structural information. The analytical value of IR spectroscopy is based on the fact that the IR bands occur at more or less localized positions in the spectrum which are correlated to the presence of characteristic structural features of the sample under study. This similarity and transferability of spectral characteristics and the corresponding structural features, makes IR a powerful tool for functional group analysis. On the other hand vibrations, and thus the exact peak positions, are sensitive to the local environment which also makes IR spectra unique molecular fingerprints, highly suited for the unambiguous identification of a sample by comparison with reference spectra. Finally, IR spectroscopy obeys Beer's Law and can thus be used for quantitative purposes too.

The major advantage of IR over other spectroscopic techniques is that practically all compounds show absorption/emission and can thus be analyzed both quantitatively and qualitatively. Besides, IR spectroscopy is nondestructive and admits in situ and remote measurement of almost any sample, irrespective the physical state and without elaborate preparations. A broad variety of advanced accessories and technologies, such as IR microscopy, optical fibers, remote sensing, reflection and emission equipment and the combination with gas chromatography (GC), liquid chromatography (LC) and supercritical fluid chromatography (SFC) sampling and measurement techniques are available to tackle a diversity of problems. The absolute sensitivity is about 50–500 picograms, which is sufficient to solve many problems in trace analysis.
IR spectroscopy is used in a broad range of environmental applications. The technique is a viable tool in remote measurements of gases, liquids and solids and as a fast and reliable method for the characterization and indicative structure classification of a wide variety of samples. Besides, IR is widely applied for identification purposes either to confirm results of other techniques or for reasons of quality assurance (QA).
Liquid Chromatography/Mass Spectrometry in Environmental Analysis
Authors: Careri M. 
Published: September 2006

Abstract
On‐line liquid chromatography/mass spectrometry (LC/MS) has become a powerful technique in environmental analysis because of the separation capabilities of liquid chromatography (LC) and the detection and identification potential of mass spectrometry (MS), the characteristics of both methods making coupling very attractive. Among the interfacing systems used to couple LC with MS, those based on the atmospheric pressure ionization (API) offer advantages in terms of sensitivity and capability to analyze highly polar, ionic, heat sensitive and high‐molecular‐weight substances. Further, the on‐line coupling of chromatographic separations with element‐selective detection systems such as inductively coupled plasma mass spectrometry (ICP/MS) is an attractive technique for trace element speciation.
The main advantage of LC/MS lies in its ability to provide qualitative information (including molecular mass and fragmentation pattern) on the detected peaks. In addition, when all the ionization parameters are optimized, quantitative analyses can be carried out and low detection limits (at the ppb level) are obtained performing selective ion detection.
In environmental analysis, universal, selective and sensitive methods are needed to afford the assay of a wide variety of target and nontarget substances. Even though gas chromatography/mass spectrometry (GC/MS) is extensively applied to the analysis of organic contaminants in several matrices, LC/MS offers major advantages over GC/MS for analyzing polar, nonvolatile and thermolabile compounds. Ultraviolet (UV) or diode‐array detector (DAD) are commonly used to perform detection in high‐performance liquid chromatography (HPLC). However, UV‐based detection methods for HPLC have several disadvantages deriving from nonspecific detection and lack of sensitivity. A more reliable identification is sometimes possible using DAD for certain compound classes, e.g. nitrophenols, in environmental samples; however, structural information is lacking for some classes of pollutants, among which are some pesticides, because their UV spectra are often almost identical. Using unspecific LC detectors, detection may be complicated by false‐positive results; in such cases, MS has proved to be an extremely valuable technique for unequivocal identification of micro‐contaminants in a variety of environmental samples.
This overview discusses recent instrumental developments concerning mass analyzers of the mass spectrometers and on‐line sample treatment procedures, with emphasis on the environmental field. Among the environmental applications of LC/MS, methods for the analysis of pesticides, polycyclic aromatic hydrocarbons (PAHs), dyes, surfactants, inorganic and organometallic compounds in environmental samples are discussed.
Organic Analysis in Environmental Samples by Electrochemical Methods
Authors: Naranjo‐Rodríguez Ignacio , Hidalgo‐Hidalgo de Cisneros José Luis 
Published: September 2006

AbstractConcern for the environment is not limited to ecological aspects, but encompasses matter such as the origin and the effects of pollutant discharges, the evaluation of environmental programs, quality control and quality assurance related to analytical precedures, and the analysis of the content of environmental matrices – both inorganic and organic – in order to control and evaluate environmental pollution. Thus, it is right to say that analytical chemistry has an important role to play in environmental analysis.A large number of analytical methods are used in environmental analysis. Some are widely used in environmental programs, and are reference/standard/official methods for the analysis of a great variety of compounds.However, there is no single universal procedure that can be applied to the analysis of any chemical species in any environmental matrix, and for any in situ/remote measurement.Electrochemical (EC) methods are widely used to investigate environmentally significant compounds, both organic and inorganic. EC research covers all important branches of environmental analysis, such as in situ/remote measurements, flow systems, combined applications with a separation technique, (bio)sensors for selective analysis, and monitoring and control procedures.This article discusses the application of these EC methods to the study of organic compounds occurring in environmental water and waste samples.
Organometallic Compound Analysis in Environmental Samples
Authors: Ebdon Les , Fisher Andy 
Published: September 2006

AbstractMany organometallic species exist in the environment and these may range from being completely nontoxic, e.g. the arsenic compound arsenobetaine, to exceptionally toxic, e.g. methyl mercury. Compounds of intermediate toxicity, such as the arsenic species dimethylarsinic acid and monomethylarsonic acid also exist. Determining the chemical form or speciation of samples is vital in environmental impact assessment as it affects bioavailability and mobility in the environment. Speciation analysis usually comprises a number of analytical steps. Sampling and sample storage are critical and must be performed in such a way that ensures a representative sample whilst preventing changes in speciation or losses of some of the more labile species. Sample preparation normally requires the extraction of the species of interest from the sample materials. This may be achieved in a number of ways that are discussed in detail in the relevant section. Sample cleanup and derivatization methods that may be required if gas chromatographic methods of analysis are to be used are also discussed. The actual sample analysis stage is discussed in detail and this concentrates mainly upon different chromatographic techniques coupled with assorted atomic spectrometric methods of detection. This is because these so‐called “coupled” techniques are used for the majority of speciation analyses. Other nonchromatographic methods of sample introduction to atomic spectrometric detection, such as hydride generation (HG), are also discussed together with techniques including more conventional detectors for the chromatographic techniques (such as ultraviolet (UV)/visible, fluorescence, flame ionization detectors (FIDs), electrochemical detectors, etc.), electrochemical methods, nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. In addition to obtaining quantitative data, techniques such as NMR and IR spectroscopy may be used to obtain structural information on individual species.Method validation is as important for speciation analysis as it is for any other analysis. This may be achieved using mass balance data, the analysis of certified reference materials (CRMs) or using completely independent analysis techniques. The text gives an overview of all stages of the analysis, highlighting potential pitfalls and areas of uncertainty.
Sample Preparation Techniques for Elemental Analysis in Aqueous Matrices
Authors: Marín Sergio R. 
Published: September 2006

AbstractThe reliability of results obtained from chemical analysis of environmental samples is related to the sample collection and preparation techniques. A succession of stages is required to obtain a result that is both accurate and representative of the initial material. The task begins by taking the appropriate precautions during collection of the liquid and solid samples, and during their later shipment to the laboratory. The environmental conditions in the laboratory where the sample will be prepared are important, as is the quality of the apparatus, containers, glassware, and reagents that are usually used. The preparation of solid waste samples requires the selection of appropriate digestion procedures, apparatus that is of high enough quality to resist the aggressiveness of some inorganic acids, and convenient systems of security for the procedures that are carried out. The information produced by the laboratory should have a high degree of reliability. For this reason, the procedures used usually permit the results obtained to be guaranteed. The more important procedures include the use of certified reference materials (CRM) and participation in interlaboratory programs. Some organizations, for example the United States Environmental Protection Agency (USEPA), have developed and distributed procedures for environmental sample preparation, which are used by many laboratories as normalized methods of reference.
Underground Fuel Spills, Source Identification
Authors: Lavine Barry K. , Moores Anthony , Ritter Jason 
Published: September 2006

AbstractWater samples from underground wells or aquifers contaminated by middle distillate fuels exist in one of two forms. Either the water sample collected from the well shows a layer of floating fuel, or the sample contains the dissolved hydrocarbons from the leaking fuel. In the worst case scenario, that of a floating fuel, the fuel layer is collected and analyzed by gas chromatography (GC). The GC profile of the fuel layer is then compared with the GC profile of the different candidate fuels to determine the fuel type of the leaking material. Usually, the gas chromatograms are compared visually, in order to obtain the best match. However, this approach to data analysis is subjective and is not always persuasive in a court of law. Visual analysis of gas chromatograms also has the drawback that it cannot take into account the influence of weathering on the overall GC profile of the fuel.Pattern recognition (PR) methods offer a better approach to the problem of matching the gas chromatograms of jet fuels because these methods involve less subjectivity in the interpretation of the data. PR methods can identify fingerprint patterns in GC data characteristic of fuel type, even if the fuel samples have been subjected to a variety of conditions. Hence, discriminants can be developed that are relatively insensitive to the changes in the overall GC profile data of the original fuel due to contamination, analytical error, or weathering.
Volatile Organic Compounds in Groundwater, Probes for the Analysis of
Authors: Patterson B.M. , Davis G.B. , McKinley A.J. 
Published: September 2006

Abstract
An automated system using a semipermeable polymer tubing [volatile organic compound (VOC) probe] coupled to an electrochemical sensor has been used for monitoring of VOCs in groundwater. The system operates by purging a VOC probe, which is in contact with groundwater, with gas at a low flow rate. The gas concentration of VOCs exiting the VOC probe can then be related to an external aqueous concentration according to Henry's law. The system enables semicontinuous in situ monitoring of total VOC concentrations in gaseous and aqueous environments.
The in situ VOC probes provided a reliable monitoring technique under long‐term (between 1 and 3 months) aggressive and dynamic field conditions. The probes provided data that were comparable to conventional techniques without the labor‐intensive sample collection and processing associated with conventional techniques, such as purge and trap or microextraction. Only the total VOC concentration can be determined using the electrochemical sensor; however, coupling the VOC probe to a gas chromatograph does enable compositional analysis to be determined.