Encyclopedia of Analytical Chemistry
Editor Highlights
Editor Highlights (April 2024)
This quarter we wish to highlight three articles covering the latest in electroanalytical techniques in the biosciences from single cell analysis to bioimaging and bioanalysis to implantable sensors. These articles join nearly 300 articles in our Encyclopedia on electrochemical based or supported analytical techniques. The three published this quarter are:
Nanoelectrochemistry for Single-Cell Analysis covers nanoelectrochemical probes which are characterized by their small size, high sensitivity, selectivity, and rapid response. Since their introduction in the 1990s, nanoelectrodes and nanopipettes have been employed for intracellular and extracellular experiments, cell topography and reactivity mapping, detection and analysis of various biological vesicles. This article discusses the fundamentals of electrochemical nanosensors and several techniques employing them, and then surveys representative applications, including measurements of oxidative stress, neurotransmitters, and electrochemical imaging of single living cells.
Electrochemiluminescence for Biomolecule Analysis utilizes electrochemiluminescence (ECL) which is a light-emitting process triggered by electrochemical reactions. Thanks to its low background, high sensitivity, wide dynamic range, and rapid response time, ECL has manifested itself as a leading signal transduction technique in biosensing and bioimaging. In recent years, much effort has been expended to extend the readout of ECL signal from the conventional intensity measurement to spectral and imaging analysis. ECL-based spectroscopy (ECLS) and ECL-based microscopy (ECLM) are thus established and became two of the most popular electroanalytical methods. Recent advances in ECL analysis not only provide insightful information on ECL reaction mechanisms but also improve the analytical performance of ECL bioassays, particularly for multiplexing capacity and spatiotemporal resolution. This monograph introduces the fundamentals of ECL, and then focuses on the progress of ECL bioassays including immunoassays, nucleic acid detection, enzymatic assays, and single-cell analysis. Finally, challenges and perspectives of ECL bioassays are discussed and presented.
Hydrogel-Based Sensing for Living Biosystems involves technology applicable to long-term in vivo monitoring of chemicals with implantable sensors. This has garnered significant interest in recent decades due to a profound impact on reflecting health conditions and aiding in disease diagnosis. Hydrogel-based sensors have emerged as a promising choice for such applications, owing to their swellable, nano-/microporous, and aqueous 3D structures, as well as their ability to maintain adjustable mechanical properties in wearable and implantable devices. This article presents a comprehensive review of the advancements in hydrogel-based sensors for living biosystems, encompassing hydrogel synthesis, functionalization, and sensing properties, along with their in vivo applications. Additionally, the article explores key challenges, implementable strategies, and future design possibilities that hold potential for researchers seeking to develop innovative, multifunctional smart sensors.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
View other new articles here
Previous Editor Highlights
Editor Highlights (August 2023)
This quarter we wish to highlight our newest Associate Editor, Maria Careri, Full Professor of Analytical Chemistry, Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Italy. She will focus on the Instrumental and Molecular Methods in Bioanalytical Chemistry content of our Encyclopedia. Professor Careri is the author of more than 230 scientific papers in peer-reviewed international journals, two book chapters, 4 chapters of encyclopedias including this quarter’s article on Liquid Chromatography/Mass Spectrometry in Environmental Analysis, and of more than 350 communications at national and international Symposia. She served in the past for many years as member of the Advisory Board of Journal of Chromatography A (Elsevier) and Analytical and Bioanalytical Chemistry (Springer). She received the “Liberti Medal” (2018) and the “Canneri Medal” (2023) (Awarding: Analytical Chemistry Division of Italian Society of Chemistry) for her research in Analytical Chemistry. In 2023 she was awarded the "Alessandro Mangia Medal" of the Bioanalytical Divisional Group of the Analytical Chemistry Division of the Italian Society of Chemistry.
The article on Liquid Chromatography/Mass Spectrometry in Environmental Analysis represents a third edition (2015 and original article in 2006) of a previous manuscript by Mattarozzi and Careri, which was updated to take into account the huge progress in MS instrumentation and related methodologies and also advances in environmental analytical chemistry. This present article covers the environmental applications of LC-MS, as well as, current and innovative approaches for the analysis of selected classes of emerging pollutants, such as micro- and nanoplastics, per- and poly-fluoroalkyl substances, and transformation products in environmental samples. The aim is to have a global coverage of the most recent research studies regarding the development of methodologies for the contaminants of high concern for the environment.
This article is one of eight articles in our Encyclopedia dedicated to LC/MS methods specifically for pesticides, plant components, peptides and proteins, clinical analysis, glycomics, and chemical warfare agents and one of 189 articles (among our total of near 1200 articles) including and comparing LC/MS with other analytical techniques for forensics, drugs, herbicides, speciation determination, alkaloids, dyes, metabolites, and many more.
The Mattarozzi and Careri article complements our comprehensive environmental analysis coverage consisting of over 100 articles spanning sampling, extraction, sample preparation, bioanalysis, electrochemistry, mass spectrometry, microscale and nanoscale systems and structures, environmental analysis, gas and liquid chromatography separations, spectroscopy, chemical reactions and selectivity, instrumentation (including field portable), imaging, satellite based sensor systems, surface analysis, hyphenated instrumentation, and data processing, databases and assessment for determination of all types of organic, inorganic, biological, radionuclide, nanoparticles and microscopic life forms and pesticides in soil pollution, water pollution and air pollution in a wide range of terrestrial, marine and tropospheric environments.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (April 2023)
This quarter we wish to highlight coverage of surface analysis techniques and applications. There are over 40 articles devoted to surface analysis in our Encyclopedia covering techniques ranging from scanning electron, tunneling, electrochemical, atomic force, fluorescence, optical, infrared and Raman microscopy; ions, electron, x-ray and electromagnetic methods including x-ray photoelectron, Auger, acoustic wave, surface plasmon resonance, ion scattering, electron energy loss, to Rutherford backscattering, and secondary ion mass spectrometry. Applications include forensics, nanoparticles, nanocrystals, coatings and polymers, biologicals, electrochemistry, paper, thin films, interfaces, catalysis, and electronics, as well as surface energetics, area and pore size.
This quarter we have two new surface analysis reviews:
The Challenges of Implementing Surface‐enhanced Raman Scattering in Studies of Biological Systems provides a summary of the state of the art of bioSERS as well as the challenges of implementing SERS spectroscopy into the investigation of biological systems and miscellaneous experimental strategies required for such studies. Examples of SERS-based analysis of biosamples are provided, ranging from the detection of simple biomolecules, followed by much more complex cell and tissue studies, and SERS-based analytical procedures for the detection of pathogens are presented.
X‐Ray Fluorescence Elemental Imaging covers Advanced X-ray focusing optics that produce a micro X-ray beam in the laboratory, leading to scanning micro-XRF analysis and XRF imaging. A confocal micro-XRF technique has been applied to visualize the elemental distributions in the samples. The fundamentals and applications of the scanning-type XRF imaging techniques are also introduced. Thereafter, two full-field XRF imaging techniques are explained, that is, wavelength-dispersive XRF (WDXRF) imaging and energy-dispersive XRF (EDXRF) imaging. In addition, the characteristics of these XRF imaging techniques are compared.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (January 2023)
This month we wish to welcome our new Associate Editor, Dr. Zhen Liu. He has been a Distinguished Professor at Nanjing University since 2014. He was appointed as a full professor at Nanjing University in 2005. He was awarded the National Science Fund for Distinguished Young Scholars in 2014. He is an associate editor of the Royal Society journal, Analytical Methods and an advisory board member of multiple journals. He serves as an executive council member of Chinese Mass Spectrometry Society, a board member of the Society for Molecular Imprinting, and member of multiple academic societies. He was awarded the 2020 Advances in Measurement Science Lectureship Award by American Chemical Society (ACS). Also, he has contributed to our Encyclopedia as an article author, most recently with an article on Boronate Affinity Chromatography.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (December 2022)
Our massive and growing Encyclopedia, with currently around 1200 articles and over 700 primary entries, was first published in print in the year 2000. It is constantly being updated online to capture advances in chemical analysis and remain as completely up to date as possible. This quarter we wish to highlight six of the articles, which were published in December 2022, which have been updated many times since initial publication and reflect the commitment of our author community to the project. At the same time, we have published another four articles which cover new topics.
Published in 2006, 2014 and, in the latest 2022 update, with new author Xiaodong Cheng.
Airborne Instrumentation for Aerosol Measurements
Published in 2006 and updated in 2009 and 2022, with the first author Leopoldo Stefanutti contributing to each update.
Deoxyribonucleic Acid Extraction Methods in Forensic Analysis
Published in 2006 and updated in 2017 and 2022 by a new author team headed by Steven B. Lee.
Quantitative Analysis, Infrared
Published in the 2000 print first edition, 2012 and 2022, with author Frédéric Cadet contributing to the original article as well as each update.
Two-Dimensional Correlation Spectroscopy: New Developments and Applications
Published in 2014, 2018 and 2022, with authors Young Mee Jung and Isao Noda for each article.
Hyperspectral Imaging and Analysis
Published in 2006, 2008, 2016 and 2022, with Paul Geladi as author of the article and all updates.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (June 2022)
Our Encyclopedia contains both theory and instrumentation articles, as well as applications articles which cover an extensive range of analytical chemistry methods and procedures. This quarter we wish to highlight four articles covering applications of key analytical techniques. The applications areas include clinical chemistry; environmental analysis; polymers; and fluorescent nanoparticles in biological systems.
Ultraviolet/Visible Light Absorption Spectrophotometry and Fluorescence Spectroscopy in Clinical Chemistry covers the range of application types for which absorption spectroscopy can be used and some examples of common analyses are given. The article also discusses physics and the merits of various instrument types with detail down to cuvettes and solvents choices as well as validation and accuracy testing. Advanced spectroscopic techniques, such as derivative spectroscopy, to enhance the data measured by the spectrophotometer are also covered. Specific current clinical applications are presented in detail.
Flame and Graphite Furnace Atomic Absorption Spectrometry in Environmental Analysis is a very well-established, reliable, and cost-effective analytical tool in thousands of laboratories throughout the world. Environmental samples trace elements analyses sampling, instrumentation, procedures, methods development and validation and detection limits, interferences, and potential instrument faults and optimization are all covered in detail as well as details of analysis of water, soils, sediments, sludges, solids, biological materials etc. There are more than 700 references.
Infrared Spectroscopy in the Analysis of Polymer Crystallinity - The theory behind the analysis of orientation in polymers using IR spectroscopy is followed by a comparison of various methods for Fourier transform infrared spectroscopy. These include transmission, attenuated total reflectance (ATR), external reflection, diffuse reflectance, photoacoustic, and emission spectroscopic techniques. Various modes of measurement such as polarized IR measurements, deuteration, and rheo-optical measurements to obtain more information from IR spectra and make the interpretation of spectra easier, as well as new techniques to combine imaging and IR spectroscopy and real-time measurements during processing are discussed.
Applications of Fluorescent Nanodiamond in Biology - The fluorescent nanodiamond is unique in that it comprises a high-density ensemble of negatively charged nitrogen-vacancy (NV−) centers that act as built-in fluorophores and exhibit a number of remarkable optical and magnetic properties. These properties make FND particularly well suited for a wide range of applications, including cell labeling, long-term cell tracking, super-resolution imaging, nanoscale sensing, and drug delivery. All of these are covered plus biocompatibility and nanodiamond surface chemistry.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (April 2022)
This month we are pleased to publish six new or updated analytical chemistry articles. We are highlighting, one of these, a new article on (Bio) Analytical Nanoscience and Nanotechnology. The article covers recent progress in exploiting the properties of nanomaterials in the development of novel (bio)analytical techniques and improved analytical methodologies specifically designed to enable nanomaterials detection, quantification, and comprehensive characterization. These are aimed at determining environmental behavior in toxicity studies or to improve the knowledge of their properties. An overview is presented on the development of novel improved bioanalytical methodologies to characterize or detect nanomaterials, along with an assessment of future directions of nanoworld-related bioanalytical applications.
This article joins twenty-six articles published in our Encyclopedia, covering the preparation and analysis of, and use in analysis of all types of nanoparticles, e.g. magnetic, superparamagnetic, carbon nanocones and nanohorns, graphene, quantum dots, hybrids, metallic, metallic oxide, antigen-specific antibodies, nanotubes, wires, composites and channels. Nano particle analytical techniques presented in detail include scanning probe microscopy, scanning electrochemical microscopy, nanopore force spectroscopy, infrared spectroscopy, tip-enhanced Raman spectroscopy, and imaging, electron microscopy, ICP-MS, NMR, field-flow fractionation with atomic spectrometric detection, resistive pulse sensing. nanopore force spectroscopy, Nanoparticle or material applications covered include, electrochemical sensing, as sorbents in microextraction, nanotoxicology, protein structure determination, nanometrology, determination of nanoparticles in the environment and foods, microbial diagnostics and disease detection, microelectronics nanoimaging and microfluidic analytical systems
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (February 2022)
This quarter we wish to highlight atomic absorption and emission analytical methods in our Encyclopedia and introduce our Assistant Editor responsible for this area, Professor Daniel L.G. Borges of the Federal University of Santa Catarina located in Florianopolis, Brazil. Professor Borges has published over 100 articles on this subject in the primary literature and has been a contributor of review articles for our Encyclopedia for the past twelve years.
This quarter we are publishing two articles on theory and instrumentation of atomic emission methods. These are Inductively Coupled Plasma Optical Emission Spectrometry and Laser-Induced Breakdown Spectroscopy and an application article, Optical Emission Inductively Coupled Plasma in Environmental Analysis.
These join our extensive coverage of the theory and instrumentation and applications of atomic absorption and emission methods. Our coverage includes more than 30 dedicated articles covering applications such as in clinical chemistry, forensics, coatings, iron and steel, detection and characterization of engineered nanoparticles, as well as food analysis; and separate detailed instrumentation presentations on background correction methods, interferences, flow injection, microdischarges, use of laser ablation and high-resolution continuum source atomic absorption spectrometry and handheld laser-induced breakdown spectroscopy instruments. Further information can be found well over 100 additional articles in which atomic absorption or emission is utilized in various applications but is not the main analytical technique covered.
Laser-Induced Breakdown Spectroscopy LIBS is a method of atomic emission spectroscopy based on a laser-generated plasma. Powerful laser pulses are focused on a sample to atomize a small mass of material resulting in the formation of a microplasma containing free atoms electronically excited to emit light. The plasma light is spectrally resolved and detected to determine the elemental sample composition based on the unique emission spectrum of each element. Because of the simplicity of the method, it is suited for analyses that cannot be carried out using conventional techniques of AES such as measurements that must be conducted outside of an analytical laboratory. A particular advantage of LIBS is the ability to analyze gases, liquids, and solids in situ, directly, with little or no sample preparation allowing rapid measurement capability. Although LIBS offers sensitive detection for many elements, it is not an ultrasensitive detection technique and, under field conditions, the method does not typically provide the high accuracy and precision offered by laboratory-based AES methods. Although basically an element detection method, complex targets (e.g. explosives, pathogens, and chemical agents) can be identified through analysis of the LIBS spectrum using advanced mathematical methods (e.g. multivariate analysis, neural networks).
Inductively Coupled Plasma Optical Emission Spectrometry This article covers in detail all of the components of ICP-OES systems and variations including theory, design, operation and analyte sensitivity. It is a powerful tool for simultaneously determining many elements in a variety of sample matrices. With this method, liquid samples are vaporized, and energized through collisional excitation at high temperature (up to 10 000 K). The atomic emission emanating from the plasma is viewed in either a radial or axial configuration, collected with a lens or mirror, and imaged onto the entrance slit of a wavelength selection device. Simultaneous multielement determinations are performed for up to 70 elements with the combination of a polychromator and an array detector. The analytical performance of such a system is competitive with most other inorganic analysis methods, especially with regard to sample throughput and sensitivity.
Optical Emission Inductively Coupled Plasma in Environmental Analysis ICP-OES has become an affordable and well-established multielement analytical method for environmental sample analysis. The method has been successfully applied for wide range of sample matrices and analytical applications, and the availability of new generation of High-resolution Inductively Coupled Plasma-Optical Emission Spectroscopy [(HR)-ICP-OES] has offered new opportunities.
Taking the USEPA (the United States Environmental Protection Agency) SW-846 solid waste analysis manual as an example, this article reviews the methods used for the preparation of samples and the ICP-OES analysis of the prepared samples for trace metals in environmental matrices. This review includes recent developments in front-end improvements in ICP-OES and detailed overview of the quality control (QC) requirements for environmental ICP-OES analysis.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (October 2021)
This quarter we wish to highlight Food Analyses methods in our Encyclopedia and introduce our Assistant Editor responsible for this area, Dr. Carlos Goncalves, Scientific and Technical Project Officer at the European Commission Joint Research Center where he is responsible for food safety and compliance.
This quarter we are publishing two articles on important aspects of analysis of foods. These are Comprehensive Two-dimensional Chromatography: An Insight into the Analysis of Food and Food Products; and Determination and Levels of Migrated Packaging Additives in Food.
These join our extensive dedicated coverage of food analysis now consisting of 33 articles covering analysis of major food components such as starch, lipids, proteins, amino acids and water as well as flavor, vitamins, enzymes, alkaloids and nanoparticles. There are articles on measurement of food properties such as viscosity and particle size, adulteration, residues, and dietary fiber, as well as more specific contaminants such as pesticides and mycotoxins. Analytical sample preparation, quality control and chemometrics are covered in detail. Techniques focused specifically on food analysis include proximate analysis, electrophoresis, Raman, near IR, fluorescence and atomic spectroscopy, liquid and gas chromatography, mass spectrometry as well as bioassays. There are an additional 400 instrumentation and applications articles that include some aspect of food analysis.
Comprehensive Two-dimensional Chromatography: An Insight into the Analysis of Food and Food Products covers multidimensional chromatography (GC and LC), employing two or more independent (or nearly independent) stationary phases depending on the physical properties of food compounds investigated. When the analysis is extended to the whole sample, the technique is called “comprehensive” and has been successfully adopted in several food application fields. Specific compound types which are covered include polyphenols, triacylglycerols (TAGs), phospholipids (PLs), and carotenoids as well as natural volatile components and xenobiotics.
Determination and Levels of Migrated Packaging Additives in Food is important as food packaging has been shown to contribute significantly to human exposure of compounds with an adverse health effect. No food-contact material (FCM) is completely inert, and reactions with the food contained within (e.g., permeation, sorption, and corrosion) may occur, leading to the release of some chemical-packaging components. Bisphenols (BPs), phthalates, and per- and polyfluoroalkyl substances (PFAS) are found in FCMs, used in their production, and are of particular health concern, the main purpose of the present chapter is to summarize the actual status on the presence of these three groups of contaminants in food: levels, major sources, most common analytical procedures for their determination, and ongoing legislation and future needs. Furthermore, non-intentionally added substances (NIAS) which can potentially migrate into food will also be covered.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (April 2021)
This quarter we wish to highlight three articles covering important applications of mass spectrometry. These are Desorption Electrospray Ionization Mass Spectrometry Imaging for Tissue Analysis; Mobile Chromatographs and Spectrometers for the Analysis of Chemical Warfare Agents; and Elemental and Isotopic Analyses in Forensic Sciences
These add to our coverage of all aspects of the theory, instrumentation and applications of mass spectrometry covered in 79 detailed articles dedicated to mass spectrometry and over 500 more in which mass spectrometry applications and instrumentation are utilized.
The article on Desorption Electrospray Ionization Mass Spectrometry Imaging for Tissue Analysis joins our collection of 79 detailed articles on mass spectrometry in providing an overview of DESI‐MSI, including basic principles, instrumentation, sample preparation, method optimization, 2D and 3D imaging, quantitation, statistical analysis, software, and applications in pharmaceutical, clinical, biomedical, plant, microbial, and forensic research. The article on Elemental and Isotopic Analyses in Forensic Sciences is a comprehensive overview of analytical techniques for elemental and isotopic analyses applied in forensic science (i.e. linking crime scene evidence to a crime by applying analytical techniques). The article provides coverage of instrumentation, techniques and applications of ICP-MS, Secondary Ion Mass Spectrometry, Thermal Ionization Mass Spectrometry, Gas Source Mass Spectrometry, Isotope Ratio Mass Spectrometry, Accelerator Mass Spectrometry and Resonance Ionization Mass Spectrometry. The article on Mobile Chromatographs and Spectrometers for the Analysis of Chemical Warfare Agents describes the technological state of readiness regarding mobile chromatographs and mass and ion spectrometers and their applicability for the analysis of chemical warfare agents (CWAs), degradation products, simulants, and precursors.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (November 2020)
This quarter we are highlighting articles authored by two of our Associate Editors, Professors Dimitri Pappas and Yukihiro Ozaki. Dimitri Pappas is an associate professor in the Department of Chemistry & Biochemistry at Texas Tech and has published both books and articles on single cell separation and analysis, while Yukihiro Ozaki is Professor Emeritus, Fellow at Kwansei Gakuin University, Department of Chemistry, School of Science and Technology. Professor Ozaki has authored several books and articles on spectroscopy and performs basic studies and applications of spectroscopies including, IR, Raman, NIR, FUV, and FIR/terahertz.
Professor Pappas has nominated articles and authors and then arranged for peer review of the articles for our Encyclopedia of Analytical Chemistry covering Single Cell Analysis, Single Cell Label-Free Profiling and also Single Cell Dielectrophoresis; and has authored articles for our Encyclopedia on Single Cell Hypoxia: Current Analytical Techniques and Future Opportunities, and now for this quarter an article on Apoptosis (Programmed Cell Death) Studied by Fluorescence Spectroscopy. The article covers several standard techniques such as flow cytometry and confocal microscopy for apoptosis study in cells. In addition, new techniques such as super‐resolution microscopy, multiphoton excitation, and single cell‐single molecule spectroscopy which are quickly emerging are covered in detail. The article explores several fluorescence approaches used in apoptosis studies and describes the mechanisms and hallmarks of the apoptosis cascade.
Professor Ozaki has nominated articles and authors and then arranged peer review of the articles These are on Nanoscale Infrared Spectroscopy and Imaging, Tip-Enhanced Raman Scattering, Plasma Spectroscopy, and Time-Resolved Spectroscopy published in our Encyclopedia. He has authored articles on Near-Infrared Imaging of Polymers; and Far- Ultraviolet (FUV) Spectroscopy in the Solid and Liquid States; as well as this quarter’s article on Far‐Ultraviolet Spectroscopy in the Solid and Liquid States, Principles, Instrumentation, and Applications. FUV spectroscopy for liquid samples has been an undeveloped research area. This article presents methods to expand the use of FUV spectroscopy, through a totally new FUV spectrometer based on the attenuated total reflection (ATR) technique that enables measurement of the spectra of liquid and solid samples in the 140–280 nm region. Applications are covered for qualitative and quantitative analyses, online monitoring, environmental geochemical analysis, and surface analysis.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (June 2020)
This quarter we wish to highlight our coverage of the identification, quantification and biological reactions of toxics, pharmaceuticals, pesticides and herbicides compounds and residues found in air, water, solid waste and food. We have just published four new articles in this field. These are: Biological Chemistry of Toxic Metals and Metalloids, Such as Arsenic, Cadmium, and Mercury, Inductively Coupled Plasma Mass Spectrometry Analysis of Environmental Samples for the Quantification of Potentially Toxic Species, DNA‐Enabled Heavy Metal Detection in Water and Trends in Multiresidue Analysis. These are the latest additions to over 400 articles in our Encyclopedia of Analytical Chemistry that cover analytical methods as applied to toxic chemicals and species in the environment as well as in chemical warfare.
An overview the analytical methodology detailed in our Encyclopedia including toxics analysis is well summarized in this quarter’s Trends in Multiresidue Analysis. Multiresidue methods mainly based on chromatographic techniques [i.e., gas chromatography (GC) and liquid chromatography (LC)] coupled to mass spectrometry (MS) are currently applied in routine laboratories. Furthermore, capillary electrophoresis (CE) has emerged as an alternative to LC and GC, owing to the development of on‐line preconcentration strategies for sensitivity enhancement. The recent integration of ion mobility spectrometry (IMS) in LC‐MS workflows also involves new possibilities for the separation of isomeric and isobaric residues, as well as for the separation of analytes of interest from background noise. New trends in multiresidue analysis point towards ambient ionization mass spectrometry (AIMS) strategies, which avoid chromatographic separations and substantially reduce analysis time. Sample preparation has evolved through the development of miniaturized and environmentally friendly procedures according to the Green Chemistry principles. In addition, generic extraction procedures for multiclass analysis have been optimized, increasing sample throughput. This article aims to show an overview of the current trends in the analysis of pesticide and drugs in food and environmental samples, discussing the relevant advances in sample treatments and the technological evolution of the instrumental techniques.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
Editor Highlights (March 2020)
This quarter we wish to highlight five articles covering important analytical instrumentation, techniques and applications of infrared and Raman spectroscopy. These are Isotopologues Detection and Quantitative Analysis by Mid‐Infrared Dual‐Comb Laser Spectroscopy, Medical Applications of Raman Spectroscopy, Raman Optical Activity of Proteins, Surface‐Enhanced Raman Spectroscopy: General Introduction, and Near‐Infrared Spectroscopy Application to the Pharmaceutical Industry. Our Encyclopedia of Analytical Chemistry contains over 1,000 detailed articles on theory, instrumentation and application of all analytical methods, nearly half of which include some aspect of infrared spectroscopy and we have over 80 articles specifically on theory, instrumentation and applications of infrared, Raman and vibrational spectroscopy.
This quarter’s article on , Isotopologues Detection and Quantitative Analysis by Mid‐Infrared Dual‐Comb Laser Spectroscopy provides techniques for massively parallel spectroscopic probing in the mid‐infrared spectral region by a frequency comb – a broad spectrum composed of some million phase‐locked equidistant sharp spectral lines – produced by a subharmonic optical parametric oscillator (OPO). Through assessing their unique rotational‐vibrational absorption signatures, we are able to simultaneously detect numerous molecules and their isotopologues in a mixture of gases, in real time and with one part‐per‐billion detection capability.
Medical Applications of Raman Spectroscopy has emerged as an important tool for label‐free characterization of biological samples due to its ability to probe water‐containing samples using visible and near‐infrared (NIR) frequencies with high chemical specificity. This article covers innovation and advancements in instrumentation such as compact lasers, sensitive detectors, and miniature fiber‐optic Raman probes which have enabled their use for medical applications. Several applications such as disease diagnosis, in vivo biopsy guidance, endoscopy, and surgical margin assessment.
This quarter’s article on Raman Optical Activity of Proteinsutilizes the small difference of Raman scattering intensities between excitations with right‐ and left‐circularly polarized incident lights, or the difference between the right‐ and left‐circularly polarized Raman scattering intensities using unpolarized excitation. The ROA spectrum reflects the conformations of chiral molecules most sensitively, providing their detailed structural information in solution. The unique capability of ROA spectroscopy has been utilized to study the conformations of various molecules in solution phase. This article features the applications of ROA spectroscopy to protein structure analyses. The ROA spectra are particularly sensitive to the secondary structures.
Surface‐Enhanced Raman Spectroscopy: General Introduction covers SERS measurement procedures, in particular the preparation of various SERS active substrates, are discussed. Based on the four important criteria in analytical science, i.e. detection sensitivity (energetic, spatial, and temporal), resolution, generality, and reliability, two different approaches to utilize the strength and offset the weakness of SERS are presented. With the enormously high sensitivity and spectral resolution, SERS has been applied successfully to surface analysis and trace analysis by gaining meaningful information from an extremely small quantity of species even down to single molecules.
Near‐Infrared Spectroscopy Application to the Pharmaceutical Industry covers Near‐infrared spectroscopy (NIR) as widely used in pharmaceutical manufacturing because it can rapidly measure the critical material attributes of a product in real time, nondestructively, and noncontact during manufacturing processes. Technology applications presented include bulk and tablet quality control, prediction of product stability and controlled release.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
December 2019
This quarter we wish to highlight three articles presenting techniques for extraction of analytes and useful compounds from various matrices. These are Solid-Phase Microextraction (SPME) and Its Application to Natural Products and Biological Samples; Supramolecular Solvents in the Analytical Process; and Supercritical Fluid Extraction in Plant Analysis; These three join our comprehensive coverage of extraction technology comprising 17 articles covering solid, liquid and gas matrices ranging from environmental samples including wastes, plants and natural products, food components, DNA extraction from biological substrates, pharmaceuticals cleanup, and clinical samples; and utilization of techniques such as Microwave‐Assisted Extraction, Pressurized Liquid Extraction including supercritical fluid, ultrasonics and other types of agitation, micro and macro systems including the long time standard, Soxhlet extraction, membrane extraction, and ionic liquid extraction.
This quarter’s article on Solid-Phase Microextraction (SPME) and Its Application to Natural Products and Biological Sample is a technique based on partitioning of analyte between the organic phase on fused silica fiber or nanomaterials coated fiber and the matrix. By controlling the polarity and thickness of the coating on fibers or tubes, sampling time, and other extraction parameters, an analyst can achieve very reliable, accurate, and highly quantifiable robust results at sub femtogram level, for gaseous to macromolecular target solutes, with a shorter analysis time compared to conventional extraction methods. Integration with gas chromatography (GC), GC-MS, HPLC, LC-MS and CE is covered.
The article on Supramolecular Solvents in the Analytical Process is based on utilization of nanostructured liquids generated spontaneously from aqueous or hydro-organic solutions of amphiphiles through a self-assembly process known as coacervation. Amphiphiles are usually natural or synthetic nonionic, ionic, or zwitterionic surfactants. This article gives an overview of the state of art of how the solvents are produced, their capability for extraction and concentration, the formats used, the strategies developed to make SUPRASs compatible with a number of detection systems, and major applications for extraction of metals and organic compounds in the biological, environmental, and agri-food areas.
Supercritical Fluid Extraction in Plant Analysis presents comprehensive information on applications and developments of supercritical fluid extraction (SFE) technique in plant oils and herbal volatile components analysis. Supercritical carbon dioxide (SC‐CO2) is the most widely system for extraction and isolation of volatile and essential oil of plants. Improvements such as the usage of modifiers make this technique applicable for the extraction of polar targets as well as nonpolar targets. Extraction of a wide range of analytes including food, agricultural agents, pharmaceuticals, cosmetics, and pesticides is covered.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
September 2019
This quarter we wish to highlight three new articles published this month in environmental analysis. These are NMR Techniques for Analysis of Contaminants in the Environment, Rapid pathogen detection tools, and Investigation of Pollution in Rivers and Groundwater by Fluorescence. These three articles join our comprehensive environmental analysis section consisting of over 100 articles covering sampling, extraction, sample preparation, bioanalysis, electrochemistry, mass spectrometry, microscale and nanoscale systems and structures, environmental analysis, gas and liquid chromatography separations, spectroscopy, chemical reactions and selectivity, instrumentation (including field portable), imaging, satellite based sensor systems, surface analysis, hyphenated instrumentation, and data processing, databases and assessment for determination of all types of organic, inorganic, biological, radionuclide, nanoparticles and microscopic life forms and pesticides in soil pollution, water pollution and air pollution in a wide range of terrestrial, marine and tropospheric environments. In addition, and supporting these analytical techniques, our Encyclopedia includes more than 200 highly detailed articles on instrumentation and theory which support the above environmental analysis coverage.
This month’s article on NMR Techniques for Analysis of Contaminants in the Environment presents a first principal understanding of NMR techniques, instrumentation and interpretation of spectra. All types of applicable NMR instrumentation are described as well. The article then summarizes current applications of NMR employed to better understand the occurrence and behavior of contaminants in the environment and draws from examples of practical applications. Examples of the use of NMR as a selective and unambiguous tool for the measurement of organofluorine compounds, using 19F NMR and of organophosphorus chemical weapons, using 31P NMR are discussed in detail. In addition, use of NMR for determination of a wide range of contaminants in ground water and soil is also detailed.
The article on Rapid pathogen detection tools contains reviews of the principles and characteristics of some recent rapid detection methods for pathogens including Escherichia coli, Salmonella spp., Listeria monocytogenes, Campylobacter jejuni, and Vibrio spp. The methods include (i) immunoassays and nucleic acid‐based detection platforms and (ii) tools based on metabolites released or consumed. Specific methodologies include: ELISA, enzyme‐linked immunosorbent assay; LFIA, lateral flow immunoassay; qPCR, quantitative real‐time polymerase chain reaction; and LAMP, loop‐mediated isothermal amplification.
The article on Investigation of Pollution in Rivers and Groundwater by Fluorescence presents the differentiation of multiple fluorescent molecules from multiple sources. The fluorescent pollutants in rivers and groundwaters are typically identified by high levels of fluorescence in the shortwave ultraviolet spectra associated with high levels of microbiological activity and biochemical oxygen demand (BOD); the presence of polycyclic aromatic hydrocarbons from landfill leachates or petroleum products; or the presence of fluorescent whitening agents (FWAs) from industrial, landfill, or sewerage pollution. These fluorescence signals are distinguished from natural organic matter fluorescence by analyzing either of the differences in spectral properties, often using multiway analysis such as parallel factor analysis, or the investigation of their sensitivity to microbial or photodegradation. Examples of the investigation of pollution in rivers and groundwaters by fluorescence using both laboratory instrumentation and in situ probes are discussed.
Robert A. Meyers, Ph.D.
Editor in Chief, Encyclopedia of Analytical Chemistry
June 2019
This month we wish to highlight our coverage of methods and applications of liquid chromatography. We present four articles this month on important techniques. These are Chiral Separations by High-Performance Liquid Chromatography, Supercritical Fluid Chromatography, Thin-Layer Chromatography, and Liquid Chromatography and Liquid Chromatography–Mass Spectrometry of Plants: Techniques and Applications. These new articles join the over 60 liquid chromatography articles already published in our Encyclopedia. Our coverage is comprehensive, covering all aspects of high pressure chromatography (including multi-dimensional, ultra-high pressure and supercritical fluids, as well as reversed-phase), ion chromatography, micro scale and capillary electrophoresis, affinity chromatography, micellar electrokinetic chromatography, all types of planar chromatography, size‐exclusion and also interraction chromatography,
Virtually every possible analyte is covered including, for example, single cell analyses, pharmaceuticals, pesticides, herbicides, food, plant components, environmental, polymers, proteins and peptides and other biologicals, forensics, as well as fuels and clinical analytes and immunoassays. And we cover liquid chromatography in combination with infra-red, a wide range of mass spectrometry approaches, nuclear magnetic resonance, spectrofluorometry, as well as ion mobility spectroscopy and others.
Robert A. Meyers
Editor in Chief Encyclopedia of Analytical Chemistry
View other new articles here