bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological Matrices: Pesticides Content Sampling, Sample Preparation and Preservation
Authors: Kawasaki Seiji , Tadano Jutaro
Published: September 2006

Environmental pollution is a world‐wide problem. Consequently, the demand for pesticide analysis in biological samples is increasing. In most cases, the availability of the test result depends on the suitability of sampling, sample preservation, and sample preparation which must satisfy the need. However, there is no reference method. This paper summarizes sampling and sample preparation and preservation methods for the case when the compound to be detected is not known.
Gas Chromatography/Mass Spectrometry Methods in Pesticide Analysis
Authors: Benfenati Emilio , Natangelo Marco , Tavazzi Simona
Published: September 2006

Gas chromatography/mass spectrometry (GC/MS) is irreplaceable in pesticide analysis. Nowadays international bodies consider mass spectrometry (MS) the method of choice for pesticide analysis and quantitative methods using GC/MS are more and more numerous.
1,2
The key characteristics of GC/MS in pesticide analysis are its selectivity and sensitivity, but other important features will be considered in detail in the specific sections on identification and quantitative analysis.

A great advantage of GC/MS in identification is that it gives a mass spectrum that can be easily and quickly compared on‐line with a library of more than 200 000 mass spectra. Specific pesticide libraries are available with hundreds of compounds. Mass spectra can be obtained with just a few picograms of compound injected and gas chromatography (GC) can separate analytes. This is an unbeatable feature of GC/MS.

In quantitative analysis, sensitivity is often excellent and selectivity is better than with other GC detectors. Multiresidue analyses can easily be done. The use of internal standards labeled with stable isotopes allows an accuracy which is not achieved with common methods. These characteristics facilitate sample processing because cleanup stages are not necessary in many cases.

Major limitations in the use of GC/MS depend on GC limits. Thus, very polar and thermally labile pesticides, not suitable for GC analysis, cannot be analyzed by GC/MS. Other limitations are the cost of the apparatus and the relative complexity of the method, compared with the simpler GC detectors. However, these limitations are gradually becoming less important as GC/MS instruments become simpler and cheaper.
Herbicide Residues in Biota, Analysis of
Authors: Headley J.V. , Dickson L.C. , Cessna A.J.
Published: September 2006

Current extraction, derivatization and clean‐up techniques, and instrumental methods are reviewed for the analysis of herbicide residues in biota. Sampling procedures are shown to be an integral part of the methodology. Herbicide analysis is seldom based on analyte‐specific methods but is usually integrated into multiresidue methods (MRMs). Current methods generally utilize relatively small sample sizes and miniaturized apparatus to take advantage of advances in instrumental performance and detection of analytes. These methods reduce the amount of solvent used for sample preparation and help to minimize waste generation. As well as using less solvent, the resulting miniaturized methods tend to be generally cheaper, faster, and less labor‐intensive than conventional methods and, furthermore, they reduce analyst exposure to hazardous materials.

Mass spectrometry (MS), interfaced with high‐resolution gas chromatography (GC), high‐performance liquid chromatography (HPLC) and capillary electrophoresis (CE), has become the detection method of choice for herbicide analysis. MS is well suited to the confirmation of target analytes and the tentative identification of unknown analytes. HPLC–mass spectrometers are becoming more widely available and less expensive. CE is a relatively new separation technique providing many advantages over traditional gas and liquid chromatography, including shorter analysis times and smaller injection volumes. There have been advances in the development of immunoassays primarily for the rapid screening for herbicide residues. These methods, once optimized, can facilitate high sample throughput at relatively low cost compared to conventional approaches. To date however, development has been limited to aqueous systems and little immunoassay work has been done for the direct determination of herbicides in biota.
High‐Performance Liquid Chromatography/Mass Spectrometry Methods in Pesticide Analysis
Authors: Cappiello Achille , Palma Pierangela
Published: September 2006

In this article, a detailed overview of the current high‐performance liquid chromatography/mass spectrometry (HPLC/MS) instrumentation, suitable for the determination of a large number of pesticides, is reported. Particular emphasis is given to the role of the mass spectrometric apparatus involved in each interfacing technique with several types of information regarding the ionization processes, analyzer principles and system configurations. The article gives an up‐to‐date picture of the current instrumentation that is available and readers will find only brief references to some important historical approaches that are no longer in use.
Phenyl‐ and Sulfonylurea Herbicides: Single Class, Multiresidue Analysis of
Authors: Trevisan Marco , Vischetti Costantino
Published: September 2006

A review of analytical methods for phenyl and sulfonylurea herbicides is reported. Extraction from environmental samples can be carried out using different techniques like liquid–liquid partition, solid‐phase extraction (SPE), microwave‐assisted solvent extraction, and so on. Both herbicide classes are analyzed mainly using high‐performance liquid chromatography (HPLC) coupled with a mass detector. Quantification limits are around the parts per billion level for many compounds. Multiresidue determination is easy for phenylurea compounds, but for sulfonylureas is limited by the different pK
a
values of the compounds.
Pesticides (New Generation) and Related Compounds, Analysis of
Authors: Picó Y. , Font G. , Moltó J.C. , Mañes J.
Published: September 2006

Miscellaneous pesticides and related compounds include the compounds that can neither be included in the classical chemical category of pesticides nor classified by their class of action. They are a heterogeneous group of substances like macrocyclic lactones, chloronicotinyls, tetranortriterpenoids, ammonium quaternary salts, dinitroanilines, acetamides, oximes, triazoles and pyridine‐based molecules. Their common characteristic is that they are recently developed pesticides. Sample preparations in environmental matrices: air, water, soil, food and biological samples are described. Analytical techniques for characterizing these compounds include gas chromatography (GC), high‐performance liquid chromatography (HPLC), and a wide variety of other emerging techniques such as capillary electrophoresis (CE), supercritical fluid chromatography (SFC), voltammetric and immunoassay techniques. Here, those applied to the field of real samples are presented.
Soil and Sediments: Pesticides Content Sampling, Sample Preparation, and Preservation
Authors: Steinheimer T.R.
Published: September 2006

For pesticide residue determination, field sampling and analysis of agricultural soils and sediments requires the consideration of several seemingly interrelated factors. The mechanisms by which pesticides are adsorbed, absorbed, and desorbed from soils are not well understood for most families of chemicals or for most soils. In addition, soil properties are both spatially and temporally variable, so that the question of sampling methodology becomes important in order to insure that the samples taken are statistically representative of the larger population being examined. Thus, the investigator must weigh the attributes and limitations of each and then choose the best overall compromise among sample size and numbers, analyte specificity, and experimental designs. Following proper collection, the laboratory analyst must then choose among several options for selective extraction techniques for removal of the pesticide analytes of interest. For most applications, one of the following will be used: a classical approach employing a suitable solvent or cosolvent mixture in either a batch shake‐out or Soxhlet extraction apparatus. Other more recently developed options include the use of extractant solvents or cosolvent mixtures held under elevated pressures and temperatures (pressurized fluid extraction (PFE)) or pure substances amended with cosolvent modifiers and held above their respective critical points (CPs) (supercritical fluid extraction (SFE)). Another option is the use of ultrasonic energy (sonication) to facilitate extraction. Each of these approaches relies upon an input of sufficient kinetic energy from an externally applied source to the sample slurried with extractant. As the binding energies responsible for the retention of pesticides on soil are overcome, sorbed solutes are released into the solution phase. Studies which address pesticide fate issues often also require determination of soil metabolite and degradate compounds along with the registered parent chemical. For many families of insecticides and herbicides, these same extraction protocols can be used to quantitatively remove the major daughter compounds from soils without requiring an additional extraction step.
Pesticides in Water: Sampling, Sample Preparation, Preservation
Authors: Liška Igor
Published: September 2006

Contamination of water by pesticides is an important issue in many regions, posing problems in the environmental, water management and health sectors. To assess the extent of contamination of water, effective and properly designed analytical methods having sufficient sensitivity and accuracy are needed. However, no matter how excellent are the state‐of‐the‐art analytical instrumentation and techniques applied, the data on trace concentrations of pesticides provided by the analytical system will be useless unless sufficient attention is given to sampling and sample preparation.

To collect a representative water sample for pesticide analysis, all sampling parameters must be selected properly. This refers predominantly to the selection of the appropriate sampling site, sampling technique and volume of the water sample. To prevent the sample matrix from any undesirable alterations during its transport from the sampling site to an analytical laboratory, physical (e.g. temperature, light intensity) and chemical/biochemical (e.g. pH, microbial growth) conditions must be under control, i.e. the sample must be preserved carefully. An efficient alternative to the transport of liquid water samples from the sampling point to the laboratory is on‐site sorption of analytes on a solid phase. This minimizes the weight of transported samples and increases the stability of analytes.

The determination of trace concentrations of pesticides in water samples and the complexity of environmental matrices require the application of an efficient sample‐handling procedure prior to separation and detection of these analytes. At present, liquid–liquid extraction (LLE) and solid‐phase extraction (SPE) are the most frequently applied sample‐handling techniques in the determination of pesticides in water. LLE is a traditional method that is still widely used in standardized methods. The increasing popularity of SPE is a result of its versatility and effectiveness and SPE is also preferred owing to the lower health risks.

The introduction of new sorbent materials, the development of automated sample‐handling systems allowing unattended operation and newly emerging sample‐handling techniques such as solid‐phase microextraction (SPME) and membrane separation methods guarantee that sample preparation in pesticide analysis will remain a fertile area of development in the future.
Mass Spectrometry, High‐Resolution, (Homolog)‐Type Analysis of Petroleum and Synfuel Distillates and Refinery Streams
Authors: Scheppele Stuart E.
Published: September 2006

The complex chemistry and chemical engineering of fossil fuel materials including petroleums, coal‐derived liquids, tar sands, shale oils, refinery streams and refined products can often be adequately simplified by expressing the composition of these materials in terms of group types. Group (chemical) types are series of homologous compounds that exhibit similar chemical properties and a regular gradation of physical properties. A homologous series of compounds, the members of which are termed homologs, contains compounds in which successive members exhibit the same difference in chemical formula with the homologous unit of present interest being CH2. Mass spectrometry (MS) is an ideal, extensively used technique in analyzing for chemical types in terms either of the total amounts of the various homologous series of compounds present in a sample or of the individual members (homologs) of the various series of homologous compounds present in a sample. The focus of this article is the fundamentals of homolog‐type analysis because analyses expressed in terms of the amounts of individual homologs rather then in terms of the total amounts of group types benefits the understanding/prediction of the effect of experimental conditions on feedstock production/transportation, product distributions in feedstock refining, end‐product quality and environmental impacts. A homolog‐type analysis also permits the determination/prediction of chemical/physical properties of a sample that can be expressed as a function of composition; examples being reaction rates, distillation curves and elemental analyses. The discussion of techniques for obtaining the “molecular ion mass spectra” required to produce homolog‐type analyses focuses on the use of all glass heated inlet systems (AGHIS) and direct probes for sample introduction, low‐voltage electrons for ion formation, and double focusing magnetic sector (DF) and Fourier transform ion cyclotron resonance (FTICR) mass analyzers to resolve isobaric ions.
Fuel Performance Specifications, Mid‐Infrared Analysis of
Authors: Mizaikoff Boris
Published: September 2006

The release of the Clean Air Act (CAA) Amendments of 1990 introduced reformulated gasoline legislation regulating the composition of fuels and particularly gasoline in order to improve the air quality by a significant reduction in vehicle exhaust emission levels. With the introduction of certain amounts of nonfuel oxygenates into fuel including various alcohols such as methanol, ethanol, t‐butanol and ethers like methyl tert‐butyl ether (MTBE), ethyl tert‐butyl ether (ETBE), tert‐amyl methyl ether (TAME) and diisopropyl ether (DIPE) a reduction of carbon monoxide (CO) and unburned hydrocarbon emissions is envisaged. Furthermore, a reduction in aromatic compounds and benzene is demanded providing a decreased release of volatile organic compounds (VOCs).

With the implementation of this program, the refining industry and their petrochemical laboratories have been forced to control accurately and to monitor continuously their gasoline blending processes. Furthermore, regulatory agencies are required to implement the use of portable analytical techniques in order to ensure the enforcement of such novel threshold values.

Besides the conventional techniques using separation‐based methods such as gas chromatography (GC), the mid‐infrared (MIR) spectral range has gained significant importance. Owing to the molecule specific absorption patterns of ethers, alcohols and aromatics, the distinct determination of fuel additives and subsequent derivation of general fuel parameters is enabled. The performance of FTIR (Fourier transform infrared) and filter‐based spectroscopic techniques will be reviewed and compared to other spectroscopic approaches. Furthermore, data evaluation procedures and ASTM (American Society for Testing and Materials) approval of these novel methods will be highlighted.
Fuels Analysis, Regulatory Specifications for
Authors: Nick Peter A.
Published: September 2006

This article provides a general survey of the chemical and physical analyses of light and mid‐range hydrocarbon fuels needed to satisfy the environmental and safety requirements of the refining and transport industries. Since the inception of the oil and automobile industries, emissions from vehicles and from fuel refineries have taken a back seat to the performance factors of the fuels themselves. In the middle of the 1900s, new environmental requirements became a commercial consideration as governments, and to a lesser extent, industrial consortia, began to impose requirements on the fuels which had little or nothing to do with performance in the engine. This article will attempt to enumerate the most prevalent of these testing specifications and provide a modest amount of information about what they involve and why they exist. At the time the original draft of this work was written in 1999, the imposition of several new regulatory criteria in the United States had just been imposed on most of the fuels production companies. Few new regulations have been enacted in the last few years (1995+) prior to this article's printing, but there have been numerous serious proposals for such new legislation and several more geographical areas have come under existing and more stringent legislation. We have tried to assess where future regulations will lead and what specifications and tests might deal with these limits.

In general, we will not deal here with the engine performance specifications. These are detailed far more adequately elsewhere in the literature. This article will not provide a long treatise on the formulation of transportation fuel manufacturing processes, and neither will it delve deeply into the testing methodology. Enough of these three subjects will be presented to allow the reader to put the regulatory specifications and what they entail into perspective. The emphasis is slanted towards the specification of gasoline range fuels, primarily caused by the great predominance of these commodities, but we do try to cover the heavier transport fuels in detail as well. There is considerable overlap in several of the specifications, at least in terms of methodology, even if the specification document number perhaps differs from light to heavier fuels.

The various testing specifications are presented by a fairly succinct description and are categorized by test type and by species analysis requirements. An attached glossary will enable the reader to become acquainted with the jargon of emissions compliance and refinery technology, since these are both linked to intelligent discussion of fuels production and usage.
High‐temperature Simulated Distillation Applications in Petroleum Characterization
Authors: Villalanti Dan C. , Raia Joseph C. , Maynard Jim B.
Published: September 2006

Simulated distillation (SimDist) is a gas chromatography (GC) technique which separates individual hydrocarbon components in the order of their boiling points, and is used to simulate the time‐consuming laboratory‐scale physical distillation procedure known as true boiling point (TBP) distillation. The separation is accomplished with a nonpolar chromatography column using a gas chromatograph equipped with an oven and injector that can be temperature programmed. A flame ionization detector (FID) is used for detection and measurement of the hydrocarbon analytes. The result of SimDist analysis provides a quantitative percent mass yield as a function of boiling point of the hydrocarbon components of the sample. The chromatographic elution times of the hydrocarbons are calibrated to the atmospheric equivalent boiling point (AEBP) of the paraffins reference material. The SimDist method ASTM (American Society for Testing and Materials) D2887 covers the boiling range 55–538 °C (100–1000 °F) which covers the n‐alkanes (n‐paraffins) of chain length about C
5
–C
44
. The high‐temperature simulated distillation (HTSD) method covers the boiling range 36–750 °C (97–1382 °F) which covers the n‐alkane range of about C
5
–C
120
. A key difference between ASTM D2887 and HTSD is the ability of the latter technique to handle residue‐containing samples (i.e. material boiling > 538 °C, 1000 °F). SimDist and laboratory‐scale physical distillation procedures are routinely used for determining boiling ranges of petroleum crude oils and refined products, which include crude oil bottoms and residue processing characterization. The boiling point with yield profile data of these materials are used in operational decisions made by refinery engineers to improve product yields and product quality. Data from SimDists are valuable for computer modeling of refining processes for improvements in design and process optimization. Precise yield correlations between HTSD and crude assay distillation (methods ASTM D2892 and D5236) have allowed HTSD to be successfully used in place of physical distillation procedures. This has given the refiner the ability to rapidly evaluate crude oils for selection of those with economic advantages and more favorable refining margins. SimDist methods are becoming more widely used in environmental applications. HTSD is useful for characterizing hydrocarbons which can be present as soil and water contaminants; for example, to map and follow hydrocarbon removal processes.
Use of Inspection Properties to Predict Hydrocarbon Fraction Physical Properties
Authors: Nick Peter A.
Published: September 2006

The chemical complexity of petroleum products has, until recently, precluded calculational techniques based on a definitive analysis of the molecular species involved. Instead, readily observed or easily (quick and inexpensively) measured macroscopic properties (gravity, boiling range, etc.) have been used to correlate information empirically. In some instances, the predictions have been “tweaked” on a local data‐centric basis or extended by quasi‐theoretical analysis.

Recent computer‐aided advancements134in multivariate electromagnetic emission, NMR (nuclear magnetic resonance) and/or MS (mass spectroscopy) analyses allow for the reliable and repeatable use of much more detailed experimental data. The ability to speciate cuts by individual chemical components will revolutionize both refining and regulation of refined products in response to the availability of quality data.

So why would one bother with older analysis and prediction methods? It is likely, given the operational sophistication and investment costs needed to deliver this highly speciated information properly, that the old ways will die but slowly. Most refineries and petrochemical plants try to get by with the minimum amount of expensive on‐line analyzers. Multivariate data generation is not yet at a state where it can easily be used for real‐time process or even product quality control. This barrier will exist for some time to come.

The historical development of crude oil processing technology has generated a great volume of data and “general” correlations, some contradictory. Most of the data upon which these methods are based have been around for 60 or more years. Many have withstood the “test of time”, being examined and verified by numerous researchers both public and private. Some of the precision of the older data may not be as good as what is generated today, but new entries to various refinery products' databanks seem to confirm the validity of the best of the older procedures and data.

The classical methods allow one to impute several otherwise unavailable characterizing pieces of data. It is essential that those engaged in the design and analysis of refinery units (which have multiple feed and product streams) become familiar with classical terminology and techniques, and eventually acquire an intuitive sense of what constitutes the “best answer” when confronted with several conflicting alternatives. The subject of this article is the proper methodology of imputing this knowledge from whatever data are at hand.
Lube Products. Molecular Characterization of Base Oils
Authors: Montanari Luciano
Published: September 2006

Base oils used in the formulation of lubricant products are a complex mixture of paraffinic (prevalently branched), aromatic and naphthenic (cycloparaffinic) molecules ranging in carbon number from 20 to 40+. Most automotive crankcase oils, accessory fluids, and many industrial lubricants contain in excess of 80% base oil in their “finished” formulation.

The compositional analysis of Lube base oils is usually obtained by a two‐step procedure. The first step separates the aromatic and saturated fractions by column chromatography (American Society for Testing and Materials, ASTM D2549). The aromatic fraction is then further characterized by mass spectrometry (ASTM D3239) and the saturated subclasses of paraffins and cycloparaffins are measured by a different mass spectrometry method (ASTM D2786).

Recently the Lube base oils have been characterized at the molecular level by means of nuclear magnetic resonance (NMR) spectroscopy. The conventional NMR spectra have the problem of signal overlap due to the presence of a great number of isomers in the base oil composition.

To overcome the problem of signal overlap, some selected multiplet subspectral carbon‐13 nuclear magnetic resonance (13C‐NMR) analyses were developed and, in particular, gated spin echo (GASPE) and distortionless enhancement by polarization transfer (DEPT) have been applied to obtain quantitative CHnsubspectra in petroleum fractions.

Usually the quantitative data obtained from GASPE have a better accuracy than those from DEPT and it will be shown how GASPE is applied to study the molecular characteristics of the aliphatic moieties of base oils of a different nature.

On the basis of the GASPE data and of the average molecular mass obtained via vapor pressure osmometry (VPO), the average number of branches and aliphatic rings can be calculated. Moreover, on the basis of GASPE, the distribution of side chain lengths and the positions of the methyl groups along the straight chain (methyls are the only groups for which the positions are directly obtained from NMR spectra) were obtained.

All these structural features are related to the finished lubricant's performance in both crankcase and industrial applications.
Lubricant Base Oils: Analysis and Characterization of
Authors: Shugarman Arnold L.
Published: September 2006

Lubricant base oils, or base stocks, are hydrocarbon lubricant components which are combined with performance additives to make finished industrial and automotive lubricants. A lubricant is a substance that reduces friction and wear between surfaces. Base oils typically comprise 80–99% of the finished lubricant. They are refined from selected crude oils, re‐refined from used oil, synthesized from specific organic compounds, or extracted from renewable resources, such as seed oils. Base oils formulated into finished lubricants help to reduce friction and wear between moving surfaces, remove heat, seal, cushion against shock loads, and remove abrasives and contaminants from the lubricated area. Base oil analysis and characterization is important for understanding how the physical and chemical properties of these materials relate to performance in finished lubricants. It is also essential for maintaining quality control (QC) over the manufacturing process, for quality assurance (QA) of the finished product, and for setting specifications between buyer and seller.
Nuclear Magnetic Resonance Characterization of Petroleum
Authors: Miknis Francis P. , Netzel Daniel A.
Published: September 2006

Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical method for determining the structure of an organic material. Developments in NMR have allowed high‐resolution spectra of materials in the solid state to be obtained. Thus, materials that have been intractable, such as kerogens and sedimentary organic matter, can now be characterized for their organic carbon structure. The combination of solid‐ and liquid‐state NMR makes NMR one of the most useful methods for the characterization of petroleum and its products.

Petroleum is formed from the maturation of sedimentary organic matter as a result of burial over geological timescales. Everyone is familiar with the products of petroleum, i.e. gasoline, diesel fuels, chemicals, and so on. All these materials, including the petroleum source rock material, can now be studied by NMR, from the genesis of petroleum to finished products such as transportation fuels. In this article, some applications of solid‐ and liquid‐state NMR to the characterization of petroleum source rocks and petroleum end products are described.
Oxygenate Vapor–Liquid Equilibrium in Gasolines
Authors: Sandler Stanley I. , Marsh Kenneth N.
Published: September 2006

Ethers and alcohols are being added to hydrocarbon fuels to produce the current generation of “clean gasolines” which are claimed to reduce air pollution. Also, alcohols provide a renewable energy source. However, the addition of oxygenates can change the volatility (as measured by the Reid vapor pressure) of a hydrocarbon mixture. This article reviews the equipment and measurement methods commonly used to study the vapor–liquid equilibrium (VLE) of hydrocarbon–oxygenate and gasoline–oxygenate mixtures. Detailed tables present those oxygenate–hydrocarbon mixtures for which VLE data are available.
Oil Shale and Shale Oil Analysis
Authors: Miknis Francis P. , Netzel Daniel A.
Published: September 2006

An oil shale can be defined as a compact rock of sedimentary origin with an ash content of more than 33% and containing organic matter that yields oil when destructively distilled, but not appreciably when extracted with ordinary solvents. This is an operational definition. There is no geological or chemical definition of an oil shale. The term is used mostly in an economic sense so that any shallow rock that yields a commercial amount of oil upon pyrolysis may be considered an oil shale. Oil shale deposits occur in at least 50 countries and the estimated potential world supply of oil from shale is 5 × 1012barrels.

The organic matter in an oil shale is mostly in the form of kerogen, which is defined as that fraction of the organic matter in a sedimentary rock that is insoluble in common petroleum solvents. The insolubility of kerogen is the main reason why an oil shale must be heated to produce liquid products. The amount of shale oil that can be produced by heating an oil shale is normally obtained from a Fischer assay. However, the Fischer assay is somewhat time‐consuming and does not provide information about what chemical properties of oil shales are important for producing liquids. Consequently, a number of alternative procedures have been developed to analyze oil shales. These procedures, along with methods of analyzing shale oils, are described in the following sections.
Mass Spectrometry, Low‐Resolution Electron Impact, for the Rapid Analysis of Petroleum Matrices
Authors: Nero Vincent P.
Published: September 2006

Common industrial analytical procedures determine the overall physical or chemical characteristics of a petroleum product, which are necessary to market the product, but these methods provide little or no information concerning specific chemical components. This article focuses on standard methods which can be used to determine the composition of individual components or classes of components within various petroleum matrices. Gas chromatography (GC) coupled with low‐resolution mass spectrometry (MS) is the most useful method for quickly identifying and precisely measuring specific components or classes of components in a petroleum matrix. Direct insertion probe mass spectrometry/mass spectrometry (DIP/MS/MS) can be used for less volatile and thermally labile petroleum components.
Chemical Reagents and Derivatization Procedures in Drug Analysis
Authors: Danielson Neil D. , Gallagher Patricia A. , Bao James J.
Published: September 2006

This article describes both pre‐ and postcolumn derivatization chemistry used in conjunction with either chromatography or capillary electrophoresis (CE) to facilitate the determination of drugs. Generally, only prederivatization is used in gas chromatography (GC), principallyto enhance the volatility, temperature stability, and/or detectability. The GC section considers derivatization of drugs by reagent class: alkylation, acylation, and silylation. The GC sample handling section describes an approach which combines the extraction and derivatization steps together. Both pre‐ and postcolumn derivatization are common approaches for high‐performance liquid chromatography (HPLC) and many of these methods have been adapted for CE. Derivatization for HPLC is often directed toward aliphatic amines, carboxylic acids, or alcohols that are difficult to detect at low levels by absorbance, luminescence, or electrochemical means. In addition, small hydrophilic molecules upon prederivatization are often converted into larger more hydrophobic compounds, making reversed‐phase HPLC easier or even feasible. The HPLC section considers derivatization of drugs based on type: alkaloids, amines, antibiotics, barbiturates, carbonyl compounds and carboxylic acids, catecholamines, hydroxy compounds, steroids, and sulfur compounds. For the GC and HPLC sections, tables are included giving the structures of the more important derivatizing agents, the analytes, and the corresponding reaction products. A brief rationale for derivatization chemistry with CE concludes this article. For CE, derivatization is often done to improve detectability since the path length for absorbance detection is very short and fluorescence can be effective using laser‐based systems.
Chiral Purity in Drug Analysis
Authors: Machida Yoshio , Nishi Hiroyuki
Published: September 2006

The preparation and evaluation of optically active compounds have become very important for the development of new drugs. The determination of chiral purity of drugs is essential in order to guarantee safety and effectiveness. Isomeric impurities may have unwanted toxicological, pharmacological, or other side‐effects. Therefore we decided to prepare an article entitled “Chiral purity in drug analysis”. This article is divided into five sections (introduction, production, regulation, evaluation methods and conclusion). In the introduction, the importance of assessing the isomeric impurities in drug analysis will be discussed. In the second section, production methods for optically active compounds, except the stereoselective synthesis method, will be summarized briefly. In particular, new trends in the production of chiral drugs, such as the simulated moving beds (SMB) method, will be described. In the third section, regulatory perspectives in the USA (Food and Drug Administration (FDA)), EC, and Japan will be described and some regulatory guidelines and guidances by, for example, the FDA, the Committee for Veterinary Medicinal Products (CVMP), and the International Conference on Harmonization (ICH) will be mentioned. In the fourth section, methods for the determination of stereoisomeric drugs will be summarized. Methods such as gas chromatography (GC), high‐performance liquid chromatography (HPLC), and capillary electrophoresis (CE) have been summarized. The focus will be on direct evaluation methods, i.e. those using chiral stationary phases (CSPs). Practical details for testing a drug's optical purity are also given.
Combinatorial Chemistry Libraries, Analysis of
Authors: Kibbey Christopher E.
Published: September 2006

Many of the analytical techniques applied to the analysis of traditional pharmaceutical compounds are used to characterize combinatorial chemistry libraries. In both cases, the medicinal chemist is primarily concerned with verifying the identity and purity of the compounds synthesized. The identity of a compound usually is confirmed spectroscopically by Fourier transform infrared (FTIR) spectroscopy, mass spectrometry (MS), and/or nuclear magnetic resonance (NMR) spectroscopy, while purity is determined using a chromatographic technique, such as high‐performance liquid chromatography (HPLC). Combinatorial chemistry libraries may contain 100–100 000 compounds present as single species or as mixtures. The need to efficiently characterize such large numbers of compounds has been the primary motivation behind the development of many of the chromatographic–spectroscopic techniques applied to the analysis of combinatorial chemistry libraries. Many of these techniques have utility outside of the realm of normal library characterization. For example, the combination of affinity chromatography and MS has proven useful for screening combinatorial chemistry libraries against specific biological targets. The major impediments to the analysis of combinatorial chemistry libraries have been the challenges of designing analytical methods compatible with the wide chemical diversity of compounds encountered in these libraries, and the unique sample preparation and handling requirements imposed by combinatorial synthesis.
Planar Chromatography in Pharmaceutical Analysis
Authors: Argekar A.P.
Published: September 2006

Planar chromatography is a liquid chromatography in which the stationary phase is arranged in the form of a planar or flat bed and the mobile phase moves by capillary action. Thin‐layer chromatography (TLC) is the most widely used planar chromatography. Modern TLC is an instrumental version of conventional TLC known as high‐performance thin‐layer chromatography (HPTLC). Rotation planar chromatography (RPL), high‐speed thin‐layer chromatography (HSTLC), and over‐pressured liquid chromatography (OPLC) are some other forms of planar chromatographic methods.

The application of HPTLC techniques for pharmaceutical analysis, such as the determination of active pharmaceutical ingredients (API) and the content uniformity test (CUT) of dosages, purity and stability tests of drugs and drug products, process monitoring of formulations, and herbal drug analysis, is described in this article. The method development of the high‐performance liquid chromatography (HPLC) technique, various pharmaceutical regulations and methods, validation and quality assurance (QA) of HPTLC experimental data and documentation are also described. The comparison of HPTLC with other chromatographic techniques is also discussed.
Proteins and Peptides Purification in Pharmaceuticals Analysis
Authors: Thrash Marvin E. , Pinto Neville G.
Published: September 2006

The biopharmaceutical market has exploded in the last 10 years, with annual sales easily exceeding a billion dollars per year. Analysis and purification are essential components in the production of therapeutic proteins and peptides, and chromatography is at the core of all pharmaceutical separations. The more popular chromatographic techniques used in the purification of proteins and peptides are reversed‐phase chromatography (RPC), hydrophobic interaction chromatography (HIC), ion‐exchange chromatography (IEC), affinity chromatography (AC) and size‐exclusion chromatography (SEC). In order to meet the challenges of the future it is essential to understand the fundamentals of each technique. In this article an overview of the more popular chromatographic techniques employed to purify biomolecules is presented. Relevant examples are also given and a discussion of detection and scale‐up is provided.
Solid‐Phase Extraction and Clean‐Up Procedures in Pharmaceutical Analysis
Authors: Campíns‐Falcó P. , Sevillano‐Cabeza A. , Herráez‐Hernández R. , Molins‐Legua C.
Published: September 2006

Solid‐phase extraction (SPE) using small cartridges filled with sorbents of a small particle size has rapidly established itself as an important sample clean‐up technique. It has prospered at the expense of liquid–liquid extraction (LLE) which is considered labor intensive and frequently plagued by problems, such as emulsion formation and use of large volumes of hazardous solvents. A remarkable characteristic of SPE is its easy adaptation to on‐line mode by column switching techniques; switching can be effected manually or by automated controllers.

The same analyte/sorbent interactions that are exploited in liquid chromatography (LC) are of use in SPE, but particle sizes employed are greater. Chemically bonded silica (SI), usually with C
18
and C
8
organic groups, is by far the most commonly used material. At present, cross‐linked polystyrene and other polymeric resins and mixed‐mode SPE sorbents are finding increasing use. A guide to improve sample clean‐up procedure can be established.

There are different approaches to automation for both off‐line and on‐line SPE, which involve different levels of apparatus cost. SPE is generally easier and cheaper than LLE. The precision obtained is similar for both techniques, while the recoveries obtained by SPE are generally better than those obtained by LLE.

Enrichment and derivatization can also be carried out by use of sorbents as supports.
Steroid Analysis
Authors: Bailey Leonard C. , Medwick Thomas , Dong Yijie
Published: September 2006

The successful determination of steroids in dosage forms and biological samples presents particular problems to the analyst in view of the great number of members of this class and their varied properties. This article discusses, according to their medicinal categories, the various classes of steroids and steroid‐like compounds which can be encountered by the pharmaceutical analyst, the general methods used in their determination, and the application of these methods to nine classes of steroidal substances.
Vibrational Spectroscopy in Drug Discovery, Development and Production
Authors: Tomellini Sterling A. , Finn James W.
Published: September 2006

The area of vibrational spectroscopy encompasses a number of versatile analytical techniques, many of which have been applied successfully to a wide variety of pharmaceutical analyses. While there are many vibrational spectroscopic techniques, some more esoteric or generally applicable than others, this chapter will concentrate on pharmaceutical applications limited to three specific areas: near‐infrared (NIR) spectroscopy, mid‐infrared (MIR) spectroscopy and Fourier transform Raman spectroscopy (FTRS). The goal of this work is to provide the interested reader with the background necessary to better understand these vibrational spectroscopic techniques and provide an overview of the breadth of applications for these techniques in analyses of pharmaceutical importance. Recently reported applications will be emphasized. The wide variety of sampling methods associated with these techniques will be highlighted throughout. Recent developments which are expected to have an impact on future pharmaceutical applications will also be discussed. Literature and other resources for advanced study are also provided.
Atomic Force Microscopy in Analysis of Polymers
Authors: Magonov S.N.
Published: September 2006

Atomic force microscopy (AFM), in which a sharp probe is employed for profiling surfaces with unique resolution, has developed into an invaluable multidisciplinary technique for advanced characterization of polymer materials. In its basic function, AFM provides high‐resolution imaging of surface structures between the scales of a few nanometers to hundreds of micrometers. This capability is useful for quantitative analysis of surface microroughness of technological surfaces with high sensitivity and accuracy. The direct visualization of polymer structures, from single macromolecules to granular and lamellar nanostructures, to microphase separation and other morphologic patterns, makes AFM an important complementary tool for many of the techniques (light scattering, chromatography, optical and electron microscopy, X‐ray diffraction analysis, etc.) employed in polymer analysis.

The advances in AFM of polymers are related to a better understanding of tip–sample force interactions and their use for examination of local sample properties. Different responses of the probing tip to surface locations with different mechanical and adhesive properties are the key for compositional imaging of heterogeneous polymer systems. Compositional mapping with AFM, which does not require any special sample treatment, substantially enhances its microscopic value. Visualization of individual components in block copolymers, polymer blends and semicrystalline materials can be performed with nanometer resolution. In addition to lateral compositional imaging, AFM probing of subsurface structures can be achieved for polymer samples with rubber‐like top layers.

A further expansion of AFM applications is expected with the imaging of polymers at different temperatures. Monitoring of polymer structural changes at thermal phase transitions could help in the understanding of polymer melting, crystallization, recrystallization, glass transition and physical aging. In such applications, AFM will complement various thermal techniques.

The review describes the basics of AFM, practical aspects of its applications to polymers and presents a broad range of examples illustrating the main trends in AFM of polymer materials.
Dielectric Spectroscopy in Analysis of Polymers
Authors: Schultz John W.
Published: September 2006

Dielectric spectroscopy is the measurement of complex permittivity (or “dielectric constant”) as a function of frequency. This measurement can also be done as a function of temperature or time at fixed frequencies to determine various physical and chemical properties of a given polymer. The permittivity is usually measured by placing the sample in contact with electrodes and applying a sinusoidal voltage. Permanent and induced dipoles, and also ion or electron conduction, all contribute to the dielectric response of a material. Dielectric spectroscopy can be used to probe molecular relaxation processes in polymers such as the glass transition or phase transitions such as a melt. For many of the relaxations, it is among the most sensitive of the thermal analysis techniques. Dielectric spectroscopy can also be used to follow chemical changes in polymer systems, such as polymer cure or aging. Because of its enormous frequency range (10
−6
–10
12
 Hz), dielectric spectroscopy can follow a wide variety of phenomena. However, since it requires either dipole rotation or charge transport, there are some molecular processes that may not be dielectrically active. In addition, analysis of the measured data can be difficult when there are different phenomena occurring simultaneously.
Dynamic Mechanical Analysis of Polymers and Rubbers
Authors: Menard Kevin P. , Bilyeu Bryan W.
Published: September 2006

Dynamic mechanical analysis (DMA) is the technique of applying a stress or strain to a sample and analyzing the response to obtain phase angle and deformation data. These data allow the calculation of the damping or tan δ, storage, loss, and complex modulus, complex viscosity and compliance. Two approaches are used: (a) forced frequency, where the signal is applied at a set frequency, and (b) free resonance, where the material is perturbed and allowed to exhibit free resonance decay. Most DMAs are the former type while the torsional braid analyzer (TBA) is of the latter. In both approaches, the technique is very sensitive to the motions of the polymer chains and it is a powerful tool for measuring transitions in polymers. It is estimated to be 100 times more sensitive to the glass transition than differential scanning calorimetry (DSC) and it resolves other more localized transitions not detected in DSC. In addition, the technique allows the rapid scanning of a material's modulus and viscosity as a function of temperature or of frequency. DMA may also be referred to as dynamic mechanical thermal analysis (DMTA), dynamic mechanical spectroscopy (DMS), or dynamic thermomechanical analysis (DTMA).