bluuebunny/crossref_metadata_2025_split huggingface dataset:
Herbicides (New Generation): Imidazolinones, Aryloxyphenoxypropionic Acids/Esters, and Diphenylethers, Analysis of
Authors: Laganà Aldo 
Published: September 2006

AbstractThis article critically examines the existing methodologies including residue isolation and preconcentration, cleanup, chromatographic analysis, such as gas chromatography (GC), high‐performance liquid chromatography (HPLC), hyphenated techniques, such as gas chromatography/mass spectrometry (GC/MS) and high‐performance liquid chromatography/mass spectrometry (HPLC/MS), and some nonchromatographic techniques, such as immunoassay (IA), of herbicide residues in crops, food, and environmental samples. The main structural groups of herbicides discussed are imidazolinones (IMIs), aryloxyphenoxy propionic acids/esters, and diphenyl ethers (DPhEs).
s
‐Triazine Herbicides and Their Transformation Products, Multi‐Residue Analysis of
Authors: Crescenzi Carlo 
Published: September 2006

Abstract
Triazine herbicides and some of their transformation products (TPs) are included in both the European Communities and United States Environmental Protection Agency (USEPA) priority list of pesticides. Owing to their widespread use and toxicity profile this family of herbicides is one of the classes of chemical pollutants that are more intensively monitored by water authorities. Many analytical methods for their determination have been published. A critical overview of these methods is presented in this paper. Conventional extraction techniques are generally nonselective and can lead to analytical interferences caused by coextracted components present in the environmental matrices. Parameters affecting extraction and problems in isolating s‐triazines, from water, soil, urine and food are discussed. The solid phase is particularly attractive because it may be coupled on‐line with chromatographic systems. Many extraction systems, in sorbent cartridge or disk format, have been developed in the last few years. Recently, interest has been growing in employing new highly selective materials such as molecularly imprinted polymers (MIPs) and immunosorbents to extract triazines from complex matrices. Strong cationic exchangers allow an effective clean‐up and are useful to improve the sensitivity of a method. Solid‐phase microextraction (SPME) is a new technique that can also be used for extracting analytes from water. This technique was successfully automated and coupled with liquid chromatography (LC). For solid matrices Soxhlet extraction is still widely used. Blending the sample in the presence of the solvent in high‐speed homogenizer machines or in an ultrasonic bath ensures complete sample disruption and a better extraction of pesticides. Microwave‐assisted solvent extraction, supercritical fluid extraction (SFE) and accelerated solvent extraction (ASE) are alternatives for conventional extraction procedures.
Both, gas chromatography (GC) and LC were successfully coupled with sensitive and selective detectors, but because of the legal implications, the analytical methods need sufficient specificity for testifying contamination. It has been recommended that analytical results indicating the presence of relevant concentrations should be confirmed by mass spectrometric methods. The use of chromatography with mass spectrometric detector and the most common interfaces (thermospray (TSP), electrospray (ES) and atmospheric pressure chemical ionization (APCI)) are illustrated. Rapid screening based on immunoassay and biosensor technologies are described. Finally some examples of recent applications are summarized.
Hydrocarbons: Gas Chromatography Procedures for On‐Line and Off‐Line Analysis
Authors: Klawun Christoph 
Published: September 2006

AbstractThe analysis of hydrocarbon mixtures originating from mineral oil sources using gas chromatography (GC) is compiled in this article and a general overview of GC and detectors, including hyphenated instrumentation, is given. The advantages and limitations of GC, as well as multidimensional GC are described in more detail from a standpoint of process GC, and the historical development of chromatography is put into perspective. Comprehensive tables of target analytes and methods offer access to all standard methods published by the American Society for Testing and Materials (ASTM) for hydrocarbon analysis with GC. Based on these tables, several subtopics are covered: gaseous and liquid hydrocarbons, heteroatom analysis, comprehensive and impurity analysis, natural gases, gasoline and fuel production, polymer feedstocks, hyphenated techniques, and bulk properties.
Metals, Nitrogen and Sulfur in Petroleum Residue, Analysis of
Authors: Robbins W.K. 
Published: September 2006

Abstract
When petroleum (i.e. crude oil) is distilled, a residual fraction containing molecules that do not volatilize is drawn off the bottom. This “resid” has an increased concentration of minor impurities, including sulfur‐, nitrogen‐, and oxygen‐bearing heterocyclics, soluble nickel and vanadium compounds and a variety of trace metals. These impurities both dominate the unique properties of the resid and play a major role in determining the refining processes necessary for its conversion to marketable products. This article introduces the common analytical techniques for the measurement of sulfur, nitrogen, nickel, vanadium, and trace metals in this challenging organic matrix.
Refractive Index Technology as a Real Time Viscosity Technique
Authors: Groetsch John G. 
Published: September 2006

Abstract
This article discusses productivity enhancement which involves using an on‐line digital process refractometer to determine the viscosity index (VI) of lube oil stocks. Since lube oils are Newtonian fluids, refractive index (RI) can be related to VI. A real‐time continuous measurement of the RI has eliminated sampling, improved product consistency, reduced waste and has helped to optimize the process.
Eluent Additives and the Optimization of High‐Performance Liquid Chromatography Procedures
Authors: Gilpin R.K. , Dudones L.P. 
Published: September 2006

Abstract
High‐performance liquid chromatography (HPLC) is one of several separation techniques that are based on the differential migration of an analyte (solute) through a fixed medium as the result of a driving force, the eluent. In the case of HPLC, the eluent is typically either a binary or ternary mixture of solvents and the stationary phase is most often a porous adsorbent or a chemically bonded phase attached to a porous substrate. The rate of migration of an individual solute and the separation between groups of solutes are governed by their interactions with the stationary phase. Thus, the optimization of an HPLC method involves the selection/adjustment of the physical and chemical parameters which control the rate of migration of the solute in such a fashion that baseline resolution is obtained between it and other co‐analytes or interfering compounds within the mixture. In doing this, given a series of closely related compounds, it is important to identify structural differences between solutes and to maximize the interactions with the stationary phase arising from them. This article considers the important physical and chemical aspects of the solute, eluent, and stationary phase in terms of chemical equilibria, solute structure, eluent conditions, operational parameters, and nonideal effects. Likewise, as several approaches may lead to acceptable analytical separations, other performance criteria such as simplicity, reliability, speed, and cost also are discussed in terms of arriving at the optimal method.
Mass Spectrometry in Pharmaceutical Analysis
Authors: Goodlett David R. , Gale David C. , Guiles Stacey , Crowther Jonathan B. 
Published: September 2006

AbstractMass spectrometry (MS) applied to the biological sciences in the pharmaceutical industry covers a broad range of application topics, such as quantitative analysis of drugs in physiological fluids, qualitative analysis of noncovalent complexes, structural analysis to determine chirality and protein sequence analysis. Regardless of the application, electrospray ionization (ESI) is the primary ionization method for transfer of nonvolatile biologics like proteins and peptides into the gas phase for analysis. It is most often used as an interface between high‐performance liquid chromatography (HPLC) separation methods and MS. The ESI process converts analytes in solution to ions in the gas phase via electrostatic nebulization at atmospheric pressure. It is characteristic of ESI to produce multiply charged analytes in a concentration‐dependent manner that is sensitive to changes in solvent, pH and ionic strength. A high voltage is applied to a liquid containing analytes as they traverse a capillary, and when the liquid droplets exit this capillary at atmospheric pressure they are directed into the source region of a mass spectrometer where desolvation is completed. Ions are then focused by an electronic gradient across a series of lenses and separated by mass/charge (m/z) using various mass spectrometer designs. Currently, the two most popular mass separation devices are quadrupoles (either single or triple quadrupole (TQ)) and ion traps (ITs). Both types of mass spectrometers are used with ESI to achieve sensitivities as low as attomoles (10−18 mol) of analyte injected onto a microcapillary HPLC column. The type of analyte, as long as it is capable of accepting a charge (addition of H+or loss of charge in negative ion mode) is relatively transparent to ESI and so a diverse range of analyte classes with disparate molecular weights can be ionized, from peptides (500–5000 amu) to proteins (10 000–100 000 amu). Depending on the construction of the source, ESI can be carried out with reversed‐phase HPLC at flow rates from 200 nL min−1to 2 mL min−1and also with capillary electrophoresis. The ease of use of ESI compared to prior techniques like fast atom bombardment has made it very popular with biologists, chromatographers and chemists who might not otherwise have been interested in MS. In fact, for many scientists ESI has made MS almost as “user‐friendly” and thus accessible as an ultraviolet (UV)–visible detector for HPLC.
Vitamins: Fat and Water Soluble, Analysis of
Authors: Bates Christopher J. 
Published: September 2006

Abstract
The vitamins are a diverse group of compounds, both chemically and analytically, because they comprise a range of biomolecules whose common properties reside solely in the fact that they are essential dietary components, which are needed in relatively small amounts to sustain life and good health. In addition, the major analytical challenges that they present are derived from the facts that (1) there is a need to quantitate them in a wide range of biological matrices, which include both foods and body fluids (for status indices); (2) the concentrations that are present are usually very low, and the ratio to other components, which can be chemically very similar, is small; (3) they may be present in several or many chemically diverse, but biologically interconvertible, forms; (4) some of them are labile to heat, extremes of pH, degradative enzymes and so on and (5) there is no single analytical approach that can quantitate all of them together, within a biological matrix.
They have been divided, broadly, into fat‐ and water‐soluble groups, and each of these has been further subdivided, mainly on a functional basis. Historically, the B‐group vitamins were measured by various microbiological assays, and the others were measured (if at all) by semispecific colorimetric assays. Nowadays, there are several more‐powerful techniques available, which include high‐pressure liquid chromatography, with a range of detectors operating over a continuous range of selective modalities; radioimmunoassay (RIA) and enzyme‐linked immunosorbent assay (ELISA)‐based techniques, which use specific protein‐binding selectivities; enzyme reactivation techniques for certain B‐vitamin status assays, and so on. The use of mass spectrometry (MS) is gainingground and can be combined with several other separation techniques, such as gas–liquid chromatography (GLC), capillary electrophoresis (CE) and so on. Measurement of vitamins in simple pharmaceutical mixtures (vitamin supplements etc.) is now reasonably straightforward.
The technical advances that these methodologies represent have greatly broadened the horizons of the vitamin analyst, and have permitted even some of the more difficult biological matrices to be addressed. However, the unsolved challenges of accurate vitamin analysis show little sign of receding, and there are very few, if any, laboratories worldwide that are currently able to measure all of the known vitamins in all known biological matrices. This remains a major challenge and a goal for the twenty‐first century.
Inverse Gas Chromatography in Analysis of Polymers
Authors: Guillet James , Al‐Saigh Zeki Y. 
Published: September 2006

AbstractThis article describes the application of inverse gas chromatography (IGC) to the study of synthetic and natural polymers. The word “inverse” is used to indicate that the component of interest is the stationary phase, either as a finely divided powder or coating, dispersed on a suitable inert support and packed into a chromatographic column. The time required for a probe molecule to pass through the column gives a measure of the molecular interactions between the probe and the polymer which can be quantified with the help of chromatographic theory. Historically, most thermodynamic studies on polymers were carried out in dilute solution, but IGC provides information on condensed phases under conditions much more similar to those under which polymers are actually used.Using this technique, melting, glass and other solid‐phase transitions can be studied and quantified. Degrees of crystallinity can be determined in an unambiguous procedure without calibration by other methods. Solubility, permeability and diffusion constants can be determined for probe molecules. IGC is also used extensively in determining the permeability of additives such as antioxidants in polymers, as well as thermodynamic quantities such as activity coefficients, heats of solution, Flory–Huggins interaction parameters (χ), and solubility parameters. Surface areas can be measured at any desired temperature by the determination of the adsorption isotherms of suitable probes. Measurements on polymer blends can yield important information on polymer–polymer interactions and can be used to predict the compatibility of the components over a wide range of temperatures. The use of finite concentration IGC provides a rapid method of determining the density of crosslinks in rubber‐like polymers.Almost any commercial gas chromatograph can be easily modified to carry out IGC experiments by procedures described in this report. The method provides a wealth of information of both fundamental and practical importance in the study of polymeric materials.
Neutron Scattering in Analysis of Polymers and Rubbers
Authors: Bucknall D.G. 
Published: September 2006

AbstractThe neutron is in many ways an ideal probe for the investigation of the structure and dynamics of materials. Elastically scattered neutrons can be used to determine the structure of the sample from the atomic to macromolecular length scales, whilst dynamic information describing the vibration, rotation and translation of these molecules is obtained from inelastically scattered neutrons. The use of isotopic substitution provides an easy route to highlighting whole or parts of a molecule in the neutron scattering experiment. Isotopic labeling has been extensively used in polymer studies owing to the large difference between hydrogen and deuterium. The combined use of neutrons often with isotopic labeling schemes has provided a wealth of detailed information about polymer materials, which could not be derived so easily by other methods.
Positron Annihilation Spectroscopy of Polymers and Rubbers
Authors: Bartoš Josef 
Published: September 2006

AbstractPositron annihilation spectroscopy (PAS) is a common name for a set of techniques based on measurements and analysis of the annihilation characteristics of a positron e+and its bound form with an electron e−, so‐called positronium (e+e−) ≡ Ps. PAS includes three basic techniques:Positron annihilation lifetime spectroscopy (PALS)Angular correlation of annihilation radiation (ACAR)Doppler broadening spectroscopy (DBS).These techniques measure the time of emission, energies and momenta of positron–electron annihilation photons, respectively. PALS measures positron and positronium lifetimes and their relative intensities, giving information about the structural–physical properties of condensed materials such as metals, ceramics and polymers, while ACAR and DBS provide information about the electron momentum and energy distribution in a material. The first technique is the most developed and it serves to characterize the microstructural features of the disordered phase of condensed matter, such as defects or free‐volume holes.
Size‐Exclusion Chromatography of Polymers
Authors: Trathnigg Bernd 
Published: September 2006

AbstractSize‐exclusion chromatography (SEC) is a standard technique for determining molar mass averages and molar mass distributions (MMDs) of polymers. Sometimes the termsgel permeation chromatography (GPC) or gel filtration chromatography (GFC) are also used, but SEC should be preferred, because this term describes the mechanism much better: polymer molecules are separated according to their hydrodynamic volumes (which can be correlated with molar mass), with the larger size molecules exiting first followed by the smaller. Molar masses are determined either from a calibration or using molar mass sensitive detectors. In the case of copolymers, the knowledge of chemical composition along the MMD is required, which can be obtained from combinations of different concentration detectors. As the hydrodynamic volumes of different polymers are typically somewhat different, molecules with different chemical composition and different molar mass will be eluted in the same slice of the chromatogram. Obviously, a discrimination between such molecules requires a two‐dimensional separation, in which one dimension may be SEC, and the other one a chromatographic technique, which separates according to chemical composition rather than molar mass, such as liquid adsorption chromatography (LAC), liquid chromatography at the critical point of adsorption (often also called liquid chromatography under critical conditions, LCCC), supercritical fluid chromatography (SFC), temperature rising elution fractionation (TREF), etc.In the lower molar mass range, mass spectroscopy competes with SEC. The most frequently used technique is matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy (MALDI/TOF/MS), which cannot, however, provide quantitatively accurate MMDs. Due to its excellent resolution in molar mass, it can be combined with chromatographic techniques in order to increase the reliability of the analysis.
Supercritical Fluid Chromatography of Polymers
Authors: Ute Koichi 
Published: September 2006

AbstractThe mobile phase in supercritical fluid chromatography (SFC) is a substance raised above its critical temperature and pressure which exhibits greater solvating properties together with reduced viscosities and higher diffusivities than its liquid state. The eluting power of supercritical mobile phase can be varied widely by controlling pressure, temperature and composition. Thus, SFC offers many advantages over high‐performance liquid chromatography (HPLC) in the characterization of polymers and oligomers. SFC of polymeric substances has been operated so far in the three modes of chromatography: adsorption chromatography for the separation of oligomer homologs, size‐exclusion chromatography (SEC) for the determination of molecular weight distribution, and adsorption chromatography at critical conditions for the characterization of functionality type distribution. The combination of SFC with supercritical fluid extraction (SFE) is useful for the analysis of polymer additives, such as stabilizers and plasticizers, in an industrial polymer material. SFC is compatible with most conventional HPLC and gas chromatography (GC) detectors, and can also be interfaced with infrared (IR) spectroscopy and mass spectrometry (MS), etc.
Thermogravimetry of Polymers
Authors: Price Duncan M. , Hourston Douglas J. , Dumont Fabrice 
Published: September 2006

Abstract
Thermogravimetry (TG) is the study of the relationship between a sample's mass and its temperature. It can be used to study any physical (such as evaporation) or chemical process (such as thermal degradation) that causes a material to lose volatile gases. Polymers have different thermal stabilities and thus the qualitative “fingerprint” afforded by TG in terms of temperature range, extent and kinetics of decomposition provides a rapid means to distinguish one polymer from another using only milligram quantities of material. Experiments are most commonly carried out under conditions where the temperature is increased in a linear fashion with time or the sample is held isothermally at an elevated temperature, although more sophisticated temperature profiles are occasionally used for compositional and kinetic analysis. Processes which do not result in a change in sample mass are not detected by TG. Therefore simultaneous measurements by differential scanning calorimetry (DSC) are useful. Volatile decomposition products may be detected and identified (e.g. by infrared (IR) spectrometry or mass spectrometry (MS)) in order to elucidate the mechanism of mass changes. TG is used for quantitative compositional analysis of polymers, lifetime prediction and kinetic studies, making the technique invaluable in all stages of polymer development, fabrication and component testing.
Flow and Sequential Injection Analysis Techniques in Process Analysis
Authors: Aldstadt Joseph H. , Olson Don C. , Wolcott Duane K. , Marshall Graham D. , Stieg Scott W. 
Published: September 2006

AbstractThe principles of flow injection analysis (FIA) and sequential injection analysis (SIA) are described as applied to industrial process monitoring. A brief history is followed by an overview of the fundamentals of FIA and SIA, with emphasis on injection methods and membrane‐assisted sample processing approaches. A discussion of the design of process instruments focuses on simplicity, maintainability, and software development. Hardware issues affecting autosamplers, fittings, pumps, and valves are also discussed. Issues affecting method development, quality control, and method validation are examined using specific examples from the chlor‐alkali and phosphate rock industries. The design and operation of on‐line sample interfaces is then described in detail. Applications in the major industrial areas are used as examples – chemical, biotechnology, manufacturing, and environmental. Finally, strengths and weaknesses are delineated and prospects for the future are presented.