bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lipid Analyses in Food
Authors: Marini Domenico 
Published: September 2006

AbstractThe term lipid encompasses a great host of compounds (e.g. fatty acids (FAs), mono‐, di‐ and triglycerides), that are almost ubiquitously present in foods; their characterization and quantification is then of importance for an analytical chemist.The first step for an accurate analysis is sample preparation: choosing an appropriate solvent or phases can isolate one particular class of lipid from a sample [a good separation of classes can be accomplised by thin‐layer chromatography (TLC)]; obviously, the sample pretreatment will be governed by the determinations to follow. Indeed, nowadays, there is a host of techniques, mainly chromatographic, for lipid analysis. TLC is a rapid way to gather information about the sample (presence of conjugated double and triple bonds, free FAs and of oxygenated FAs), particularly with the development of modified normal phases. For example, silica gel can be impregnated with boric acid, which inhibits isomerization of mono‐ and diglycerides, or it can be treated with silver ions [argentation, for silver ion thin‐layer chromatography (Ag‐TLC)] used for resolution of unsaturated FAs. Gas chromatography (GC) and high‐performance liquid chromatography (HPLC) are the most common techniques actually employed, because of their versatility (many parameters can be changed, e.g. stationary and mobile phases, detector) and to their capacity to be hyphenated (coupled with another measuring device). Particularly, the advent of the light‐scattering detector has allowed greater reproducibility in the HPLC of lipids. Mass spectrometry (MS) is often coupled with GC. However, coupling MS with another MS (MS/MS or tandem MS) is useful for the determination of the structure of long‐chain FAs with improved selectivity and sensitivity. Finally, nuclear magnetic resonance (NMR) is able to identify functional groups, even in mixtures, and is a valid aid for the elucidation of structures with double bonds (DBs) by interpretation of the coupling patterns.Each analytical method relies on appropriate sample preparation (e.g. methylation for the GC analysis of FAs) and a critical approach to evaluate its usefulness.
Chiroptical Spectroscopy in Drug Analysis
Authors: Brittain Harry G. 
Published: September 2006

Abstract
Many pharmaceutical compounds contain one or more centers of dissymmetry, thus presenting a unique series of regulatory and compendial requirements. The regulatory authorities are well acquainted with the fact that one given enantiomer or diastereomer of a drug entity may possess more efficacy (or fewer side effects) than its mirror image. Consequently, unless a compelling argument exists for the marketing of a racemate, it is more appropriate to develop enantiomerically pure therapeutic agents. Although most often characterized using chiral chromatography, these molecules can be effectively studied using the various techniques of chiroptical spectroscopy. Techniques that have been found to be very useful for such work include polarimetry (i.e. circular birefringence), optical rotatory dispersion (ORD), and circular dichroism (CD). At present, regulatory authorities remain fixated on the use of polarimetry to establish enantiomeric identity and purity, but as their awareness grows so will an acceptance of the more sophisticated chiroptical techniques. In this article, the principles underlying each chiroptical effect are briefly outlined and the application to problems of pharmaceutical interest is illustrated through the inclusion of appropriate examples.
Microspectrophotometry in Forensic Science
Authors: Ziȩba‐Palus Janina 
Published: September 2006

AbstractInfrared microspectrophotometry is a combination of two techniques – optical microscopy and infrared (IR) spectrometry – which supply specific information about the composition and structure of a given material. The equipment used is a Fourier transform infrared (FTIR) spectrometer connected on line with an optical microscope.The microscope allows observation of a sample in white light at relatively high magnification; this allows its morphology and microstructure to be established, and facilitates selection of the area which will subsequently be subjected to IR spectrometric analysis. The microscope also permits use of polarized light in investigations.The spectrometer enables analysis of a sample with a chosen measuring technique – transmission or reflection – with the aim of determining the chemical composition of the sample. It also supplies information about its microstructure and orientation.This method is particularly useful in the analysis of trace amounts of various substances secured as material evidence in court cases, and in analysis of the homogeneity of the sample, identification of inclusions and contaminants on the surface, and detection of structural defects.A specific advantage of this method is its ability to unambiguously photograph and record marked and measured areas of the sample and minimize the process of preparing the sample for analysis.Furthermore, IR microspectrophotometry gives the rare opportunity of studying small crystals or areas in the oriented materials by using polarized IR radiation, both by the transmission and the reflection technique.Its fundamental drawback is that the physical nature of the microsample may influence the precision of the photometric measurements and cause distortion of the spectra (artefacts) obtained. Furthermore, because only a small area is studied the heterogeneity of the sample and the amount of contaminants may significantly influence the results of spectrometric measurements.Microspectrophotometry in the ultraviolet/visible (UV/VIS) range is a combination of photometric measuring techniques and optical microscopy. It allows comparison of the color of very small samples of various materials, such as single fibers, tiny amounts of paint, traces of ink or ball‐point pen ink on a forged document in an objective way, independently of the sharpness and quality of the observers's vision. It yields immediate information about spectral differences existing between two samples of similar color, which are indistinguishable by use of the optical microscope. Additionally, using appropriate software to analyze the results of microspectrometric measurements, it enables precise measurement of a color, and – applying the theory of colors – gives a color a defined numerical value; this facilitates communication between experts working with this method. The equipment consists of an optical microscope with a spectrometer for analysis in the visible and ultraviolet range, connected to a microcomputer via an analog‐to‐digital converter.
Direct Reading Instruments for the Determination of Aerosols and Particulates
Authors: Pui David Y.H. , Chen Da‐Ren 
Published: September 2006

Abstract
Solid and liquid particles suspended in a gas are referred to as aerosols. The suspending medium can be air, or some other gases, such as argon, nitrogen, helium, etc. Aerosols have found numerous scientific and technical applications. Beneficial applications include pharmaceutical aerosols for medical inhalation therapy or diagnosis, industrial aerosols for coating wave guides, refractories, gas sensors and semiconductors, as well as particles ofmodern materials for forming advanced ceramics, optical and optoelectronic devices, cosmetic products, paint pigments, and catalysts. Harmful effects of aerosols include atmospheric aerosols that contribute to urban air pollution and global radiation balance, dust particles ingested by engines causing premature failure of the equipment, and particles deposited on semiconductor wafers causing device failure and product yield loss.
Aerosols and particles can be analyzed by collecting them on a filter or a sampling surface for subsequent microscopic, gravimetric, or chemical analyses. The collection by the samplers gives an integrated sample and a time averaged concentration over a period of hours or days. Direct reading instruments carry out the sampling and analysis within the instrument and the property of interest can be obtained in near real‐time. Direct reading instruments are available to cover particles in the size range of 0.002 to 100 µm. These instruments have fast time response and can follow rapid changes in both particle size and concentration. Good counting statistics can also be obtained because repeated measurements can be performed in a short time. However, these instruments usually rely on indirect sensing techniques and more calibration efforts are usually required.
Spectroscopic Techniques in Industrial Hygiene
Authors: Wang Jin , Siegel Paul D. , Lewis Daniel M. , Vo Evanly , Wallace William E. , Ashley Kevin , Stettler Lloyd E. 
Published: September 2006

AbstractOver the past few decades the pace of change in spectroscopic techniques has been remarkable. Spectroscopic techniques are emerging as important, powerful, and versatile tools in determining exposure levels of hazards generated in working environments. Occupational safety and health studies employ spectroscopic techniques to analyze hazardous chemicals, biomarkers, and particulate matters of exposure. In comparison with many traditional detection techniques such as gravimetric methods, spectrometric techniques are much more sensitive, selective and accurate. The major spectroscopic techniques used in industrial hygiene include mass spectrometry (MS), scanning electron microscopy (SEM), X‐ray microanalysis (XM), atomic spectrometry (AS), ultraviolet/visible (UV/VIS) photometry, fluorescent spectrometry (FS), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy (RS). Interest in using MS in industrial hygiene is driven by its value in understanding basic physical, chemical, and biological processes related to workers' exposure to occupational hazards, and in devising new methodologies to monitor exposures. SEM has become particularly useful in the study of pneumoconioses and workplace environmental particles since being complemented with energy dispersive X‐ray (EDX) analysis and automated image analysis capabilities. SEM and EDX have been used extensively to characterize particles found in lung tissues. Atomic spectrometric methods are used widely for occupational health evaluation of inorganicmetals. The development of inductively coupled plasma atomic emission spectrometry (ICPAES) techniques has become increasingly attractive, and has been applicable to analysis of nearly all the elements. FTIR and Raman spectroscopies are employed to detect highly toxic gas and vapor mixtures. Additionally, field‐portable methods for monitoring airborne workplace contaminants and toxins have received increasing attention. To date, highly specific, selective, and sensitive spectroscopic technologies have allowed for the development of novel methodologies and new indicators for exposure characterization. Assessment of actual body burden of chemicals, which are more directly related to potential adverse occupational health effects, can be accomplished. The major spectroscopic techniques and their applications to industrial hygiene are described in this article.
Filtration in Particle Size Analysis
Authors: Droppo Ian G. 
Published: September 2006

Abstract
Filtration is defined as the separation of solid particles from a liquid or gas by passing the suspension through a porous, fibrous or granular substance. In science and industry, filtration is commonly used for the concentrating and/or removal of particulate matter or for the separation of particles into size classes for subsequent physical, chemical or biological analysis. Separation of particles into multiple size classes is often required for the assessment of particle size. There are many different types of filters available (e.g. fibrous, membrane, polycarbonate) for particle characterization through filtration. The type of filter to be used for particle size characterization is dependent on a number of considerations such as sample (particle) characteristics, collection efficiency, pore size and structure and analytical compatibility. Filtration has the advantage of being one of the few techniques which allow for the physical separation of particles into different size classes for distribution or chemical–biological analysis. If appropriate precautions are taken to minimize sample perturbations (e.g. select appropriate filter for the application, filter in the field, avoid overloading a filter, ensure a low flow rate and stir if possible), a reasonably accurate estimate of particle size can be obtained. Generally, errors associated with filtration arise from filter clogging and when attempting to characterize flocculated/aggregated particles. The basic nature of a suspended aggregate (i.e. fragile, plastic, high water content) means that it is likely to be broken up or created owing to the often tortuous nature of filtration, or be deformed on the surface or within the filter owing to pressure effects. This has implications if optical image analysis of the filter is to be used for particle size analysis as the true particle morphology and size will have been altered. In such an instance, if only a grain size distribution is required, it is suggested that optical image analysis be employed in conjunction with a plankton chamber settling technique rather than with filtration.
Ultrasonic Measurements in Particle Size Analysis
Authors: McClements David Julian 
Published: September 2006

AbstractThe particle size distribution and concentration of a colloidal dispersion can be determined by measuring its ultrasonic velocity and/or attenuation coefficient as a function of frequency and then using a suitable mathematical model to interpret the spectra. Ultrasonic spectroscopy can be used to analyze particle sizes between about 10 nm and 1000 µm, and is suitable for application to concentrated systems (often up to 50 wt%). This technique has considerable advantages over many alternative technologies because it can be applied to systems that are optically opaque without the need of any sample preparation.
Capillary Electrophoresis of Peptides
Authors: Oda Robert P. , Strausbauch Michael , Landers James P. 
Published: September 2006

AbstractThe ability to resolve effectively peptides obtained by chemical or proteolytic cleavage is important in the structural investigation of proteins, whether it be minute amounts of protein isolated from a biological source or protein produced recombinantly for pharmaceutical use. Capillary electrophoresis (CE) can be used rapidly to resolve peptides electrophoretically in free solution with a selectivity that differs from that of other separation approaches. In this article, we provide a description of the instrumentation for CE and the fundamental principles driving peptide separation at low and high pH. Guidelines for method optimization of peptide injection and separation by CE are given along with a number of examples from the literature demonstrating the utility of CE for interrogating protein structure via CE‐based peptide and glycopeptide analysis.
Chromatography of Membrane Proteins and Lipoproteins
Authors: Zolla Lello 
Published: September 2006

AbstractThe available methods for the separation of membrane proteins and lipoproteins are sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS/PAGE), followed by immunoblotting, isoelectric focusing (IEF), capillary electrophoresis (CE) and high‐performance liquid chromatography (HPLC). In this article it is shown that HPLC techniques, given their wide versatility, relative ease of use, and high resolution, may be considered the most valuable tool for the characterization of virtually any hydrophobic protein. Moreover, HPLC is not a destructive technique and therefore proteins, once separated, are available for further analytical investigations. Application examples are described and comparisons with other methods are discussed.
Protein–Drug Interactions
Authors: Oravcová Jana , Lindner Wolfgang 
Published: September 2006

AbstractNoncovalent (reversible) drug–protein binding interactions are an integral part of intermolecular recognition processes taking place in a cell or organ environment. Characterization of basic constraints of target protein binding site(s) (affinity, stoichiometry, specificity, saturability and stereoselectivity) for particular ligand(s) is an essential output of many different drug–protein binding studies. Nonlinear and stereoselective binding phenomena, including drug–drug (or enantiomer–enantiomer) interactions and their e.g. genetically or pathophysiologically determined variability, can be predicted in this way. In general, the methods used for drug–protein binding studies can be divided into separation (nonspectroscopic) and spectroscopic methods. Separation methods are particularly suitable for the quantitative determination of drug binding, whereas spectroscopic techniques are able to characterize the qualitative features of drug–protein complexes (e.g. conformational status/changes). The primary objective was to summarize the most relevant trends in separation techniques [affinity high‐performance liquid chromatography (HPLC) and affinity capillary electrophoresis (ACE)] employed in the framework of drug–protein/biopolymer binding assays and to compare them with so‐called conventional approaches (equilibrium dialysis (ED), ultrafiltration). Focused attention has been paid particularly to HPLC and capillary electrophoresis (CE) methods designed for drug–protein studies when so‐called “dynamic” and “secondary” equilibria are involved and created. A common feature of this strategy is to use binding protein(s) or interacting drug(s) without their covalent immobilization as mobile phase or background electrolyte (BGE) (buffer) additives. This offered a new, elegant tool for the separation of “bound” and “free” forms of interacting species in a “miniaturized free solution system” operating under nearly physiological conditions. Undoubtedly, it permits simplification of the experimental protocols where it is crucial to perform repetitive analyses under “the same starting conditions”, as e.g. the occupancy of binding sites is concerned.
Protein–Oligonucleotide Interactions
Authors: Gabrielsen Odd Stokke , Matre Vilborg , Bergholtz Stine 
Published: September 2006

Abstract
The specific binding of a protein to a nucleic acid is a first step in several central processes in a living cell. Sequence‐specific protein–DNA interactions are crucial for the functional read‐out of genetic information. Sequence recognition is the result of a concerted action of many weak chemical interactions of different types between the protein and its DNA target, including nonspecific electrostatic interactions, hydrogen bonding and van der Waals contacts. The precise complementarity of shape between the two macromolecules facilitates specific chemical recognition to be established. The electrophoretic mobility shift assay (EMSA) and several variants of footprinting are simple electrophoretic methods developed to study protein–DNA interactions. Because the specificity is determined by the nucleic acid sequence, the same methods can be exploited for a wide range of proteins simply by changing the sequence of the nucleic acid. EMSA detects sequence‐specific DNA‐binding activity in a protein sample as a separate migrating band in a nondenaturating gel. A footprinting method provides more detailed information on the precise location of a bound protein along the DNA fragment through the removal of specific bands in a pattern of cleaved fragments separated by electrophoresis. Both methods are highly sensitive due to the use of radioactively labeled oligonucleotides and can be performed with protein samples of low purity. When combined these methods are capable of providing a picture of the protein–DNA complex with a great deal of molecular detail, surpassed only by the more demanding methods of crystallography and nuclear magnetic resonance (NMR).
Carbamate and Carbamoyloxime Insecticides: Single‐Class, Multiresidue Analysis of
Authors: Honing Maarten 
Published: September 2006

AbstractLarge quantities of modern pesticides such as theN‐methyl‐ and carbamoyloxime carbamates (over 1000 t of theN‐methylcarbamate carbaryl) are used for agricultural as well as for nonagricultural purposes. The European Union (EU)‐permitted concentration levels of these insecticides and their related transformation products in drinking water is 0.1 µg L−1, and the maximum for the total pesticide content has been set to 0.5 µg L−1. Many analytical procedures, focusing on sample pretreatment, column chromatographic separation, and sensitive detection, have been reported for the trace‐level determination of these compounds. This article surveys the application of these techniques, and their potential with regard to recovery, resolution, sensitivity, and robustness is discussed.For example the reproducibility of results with a variety of carbamates from water samples or pretreated biological/soil samples is an essential criteria during the development of extraction procedures. The percentage of recovery influences the sensitivity of the total analytical method. Good results with solid‐phase extraction (SPE) are obtained with a C18/OH phase which is used on a routine basis by various analytical laboratories for the analysis of surface waters and vegetables. This technique is superior to liquid–liquid extraction (LLE) for reasons explained in this article. Chromatographic resolution is most effective, when gas chromatography (GC) is used. Unfortunately, thermal degradation of some carbamates in the injector takes place, making liquid chromatography (LC) the separation technique of choice despite the fact that some carbamates cannot now be separated. Capillary electrophoresis (CE) offers better separation efficiency but is still not a robust technique. Another way to solve the coelution problem is the application of mass spectrometry (MS). Utilizing the selected ion monitoring mode, coeluting compounds can be quantified. MS adds an extra separation step because ionized compounds are separated by the mass‐to‐charge ratio. Application of the ionspray (ISP) and the heated nebulizer (HN) interfacing techniques makes possible the quantification of carbamates at trace levels as low as 0.1 ng L−1in drinking water, without any sample preconcentration. Furthermore, MS also offers the ability to confirm the identity of the compounds. On‐line SPE in combination with liquid chromatography/mass spectrometry (LC/MS) or, better, liquid chromatography/tandem mass spectrometry (LC/MS/MS) is the best method for the quantification and structural confirmation of carbamate pesticides at concentration levels of 0.1 ng L−1or lower.
Gas Chromatography and Supercritical Fluid Chromatography with Selective Detection in Pesticide Analysis
Authors: Carrasco Pilar Bou , Bayona Josep M. 
Published: September 2006

AbstractPesticide determination by gas chromatography (GC) and supercritical fluid chromatography (SFC) techniques has been presented in this article. Instrumentation used in the different pesticide class analyses, such as injection (vaporizing, cold injection and large volume) and detection techniques (nitrogen–phosphorus detection, NPD; flame photometric detection, FPD; electron capture detection, ECD), and hyphenated systems (atomic emission detection, AED; mass spectrometry, MS; Fourier transform infrared, FTIR) used in GC and SFC determination of pesticides are presented. The figures of merit of each detection technique are outlined. Instrumental set‐ups which combine extraction and separation techniques are also presented. Stationary phases used in GC and the type of SFC columns used in the determination of pesticides are also reported. Finally, the application of recent GC developments in the determination of pesticides is mentioned.