Showing papers in "Critical Reviews in Analytical Chemistry in 2016"
TL;DR: The FTIR vibrational spectroscopy is presented, without claiming to cover entire field, for the characterization of diamond, amorphous carbon, graphite, graphene, carbon nanotubes, fullerene and carbon quantum dots.
Abstract: Fourier transform Infrared (FTIR) spectroscopy is a versatile technique for the characterization of materials belonging to the carbon family. Based on the interaction of the IR radiation with matter this technique may be used for the identification and characterization of chemical structures. Most important features of this method are: non-destructive, real-time measurement and relatively easy to use. Carbon basis for all living systems has found numerous industrial applications from carbon coatings (i.e. amorphous and nanocrystalline carbon films: diamond-like carbon (DLC) films) to nanostructured materials (fullerenes, nanotubes, graphene) and carbon materials at nanoscale or carbon dots (CDots). In this paper, we present the FTIR vibrational spectroscopy for the characterization of diamond, amorphous carbon, graphite, graphene, carbon nanotubes (CNTs), fullerene and carbon quantum dots (CQDs), without claiming to cover entire field.
660 citations
TL;DR: The ability to quantify levels of target analytes in biological samples accurately and precisely in biomonitoring involves the use of highly sensitive and selective instrumentation such as tandem mass spectrometers and a thorough understanding of highly variable matrix effects.
Abstract: The ability to quantify levels of target analytes in biological samples accurately and precisely in biomonitoring involves the use of highly sensitive and selective instrumentation such as tandem mass spectrometers and a thorough understanding of highly variable matrix effects. Typically, matrix effects are caused by co-eluting matrix components that alter the ionization of target analytes as well as the chromatographic response of target analytes, leading to reduced or increased sensitivity of the analysis. Thus, before the desired accuracy and precision standards of laboratory data are achieved, these effects must be characterized and controlled. Here we present our review and observations of matrix effects encountered during the validation and implementation of tandem mass spectrometry-based analytical methods. We also provide systematic, comprehensive laboratory strategies needed to control challenges posed by matrix effects in order to ensure delivery of the most accurate data for biomonitoring studies assessing exposure to environmental toxicants.
230 citations
TL;DR: The aim of this article is to review the available information on analytical methods for gallic acid, as well as presenting the advantages and limitations of each technique.
Abstract: Gallic acid (3,4,5 trihydroxybenzoic acid) is a secondary metabolite present in most plants. This metabolite is known to exhibit a range of bioactivities including antioxidant, antimicrobial, anti-inflammatory, and anticancer. There are various methods to analyze gallic acid including spectrometry, chromatography, and capillary electrophoresis, among others. They have been developed to identify and quantify this active ingredient in most biological matrices. The aim of this article is to review the available information on analytical methods for gallic acid, as well as presenting the advantages and limitations of each technique.
139 citations
TL;DR: Recent preconcentration of trace elements, organic compounds, and biological species using SPE-based graphene, graphene oxide, and their modified forms are focused on.
Abstract: Graphene is a new carbon-based material that is of interest in separation science. Graphene has extraordinary properties including nano size, high surface area, thermal and chemical stability, and excellent adsorption affinity to pollutants. Its adsorption mechanisms are through non-covalent interactions (π-π stacking, electrostatic interactions, and H-bonding) for organic compounds and covalent interactions for metal ions. These properties have led to graphene-based material becoming a desirable adsorbent in a popular sample preparation technique known as solid phase extraction (SPE). Numerous studies have been published on graphene applications in recent years, but few review papers have focused on its applications in analytical chemistry. This article focuses on recent preconcentration of trace elements, organic compounds, and biological species using SPE-based graphene, graphene oxide, and their modified forms. Solid phase microextraction and micro SPE (µSPE) methods based on graphene are disc...
96 citations
TL;DR: Different methods and steps of surface modification of this electrode material for biosensing and construction of biosensors are discussed.
Abstract: Boron-doped diamond (BDD) is a prospective electrode material that possesses many exceptional properties including wide potential window, low noise, low and stable background current, chemical and mechanical stability, good biocompatibility, and last but not least exceptional resistance to passivation. These characteristics extend its usability in various areas of electrochemistry as evidenced by increasing number of published articles over the past two decades. The idea of chemically modifying BDD electrodes with molecular species attached to the surface for the purpose of creating a rational design has found promising applications in the past few years. BDD electrodes have appeared to be excellent substrate materials for various chemical modifications and subsequent application to biosensors and biosensing. Hence, this article presents modification strategies that have extended applications of BDD electrodes in electroanalytical chemistry. Different methods and steps of surface modification of this electrode material for biosensing and construction of biosensors are discussed.
84 citations
TL;DR: There still remains a lack of a suitably sensitive and widely applicable methodology able to take into account the various different aspects of adulteration, considering coffee varieties, defective beans, and external agents.
Abstract: Coffee is a ubiquitous food product of considerable economic importance to the countries that produce and export it. The adulteration of roasted coffee is a strategy used to reduce costs. Conventional methods employed to identify adulteration in roasted and ground coffee involve optical and electron microscopy, which require pretreatment of samples and are time-consuming and subjective. Other analytical techniques have been studied that might be more reliable, reproducible, and widely applicable. The present review provides an overview of three analytical approaches (physical, chemical, and biological) to the identification of coffee adulteration. A total of 30 published articles are considered. It is concluded that despite the existence of a number of excellent studies in this area, there still remains a lack of a suitably sensitive and widely applicable methodology able to take into account the various different aspects of adulteration, considering coffee varieties, defective beans, and external agents.
83 citations
TL;DR: Four sensing configurations with two ways, attenuated total reflection (ATR) and diffraction, to excite the surface plasmons, and four major types of biosensors, immunosensor, DNA biosensor, enzyme bios sensor, and living cell biosensor are discussed in detail for their sensing principles and applications.
Abstract: Fiber optic-based biosensors with surface plasmon resonance (SPR) technology are advanced label-free optical biosensing methods. They have brought tremendous progress in the sensing of various chemical and biological species. This review summarizes four sensing configurations (prism, grating, waveguide, and fiber optic) with two ways, attenuated total reflection (ATR) and diffraction, to excite the surface plasmons. Meanwhile, the designs of different probes (U-bent, tapered, and other probes) are also described. Finally, four major types of biosensors, immunosensor, DNA biosensor, enzyme biosensor, and living cell biosensor, are discussed in detail for their sensing principles and applications. Future prospects of fiber optic-based SPR sensor technology are discussed.
71 citations
TL;DR: This article comprehensively reviews research advancements in the generation of aptamers, analyses physicochemical conditions affecting their binding characteristics to cellular and biomolecular targets, and discusses various field applications of aptameric binding.
Abstract: The quest to improve the detection of biomolecules and cells in health and life sciences has led to the discovery and characterization of various affinity bioprobes. Libraries of synthetic oligonucleotides (ssDNA/ssRNA) with randomized sequences are employed during Systematic Evolution of Ligands by Exponential Enrichment (SELEX) to select highly specific affinity probes called aptamers. With much focus on the generation of aptamers for a variety of target molecules, conventional SELEX protocols have been modified to develop new and improved SELEX protocols yielding highly specific and stable aptamers. Various techniques have been used to analyze the binding interactions between aptamers and their cognate molecules with associated merits and limitations. This article comprehensively reviews research advancements in the generation of aptamers, analyses physicochemical conditions affecting their binding characteristics to cellular and biomolecular targets, and discusses various field applications of aptameric binding. Biophysical techniques employed in the characterization of the molecular and binding features of aptamers to their cognate targets are also discussed.
54 citations
TL;DR: Four mechanism types of signal generation in amperometric sensors with ionic liquid are described and the influence of selected physico-chemical properties of the ionic liquids on the metrological parameters of these sensors is described.
Abstract: This article presents an analysis of available literature data on metrological parameters of the amperometric gas sensors containing ionic liquids as an electrolyte. Four mechanism types of signal generation in amperometric sensors with ionic liquid are described. Moreover, this article describes the influence of selected physico-chemical properties of the ionic liquids on the metrological parameters of these sensors. Some metrological parameters are also compared for amperometric sensors with GDE and SPE electrodes and with ionic liquids for selected analytes.
52 citations
TL;DR: The diagnostic applications of ammonia measurement and the impact that the move from blood to breath analysis could have on how these processes and diseases are studied and managed are explored.
Abstract: Ammonia is an important component of metabolism and is involved in many physiological processes. During normal physiology, levels of blood ammonia are between 11 and 50 µM. Elevated blood ammonia levels are associated with a variety of pathological conditions such as liver and kidney dysfunction, Reye's syndrome and a variety of inborn errors of metabolism including urea cycle disorders (UCD), organic acidaemias and hyperinsulinism/hyperammonaemia syndrome in which ammonia may reach levels in excess of 1 mM. It is highly neurotoxic and so effective measurement is critical for assessing and monitoring disease severity and treatment. Ammonia is also a potential biomarker in exercise physiology and studies of drug metabolism. Current ammonia testing is based on blood sampling, which is inconvenient and can be subject to significant analytical errors due to the quality of the sample draw, its handling and preparation for analysis. Blood ammonia is in gaseous equilibrium with the lungs. Recent research...
50 citations
TL;DR: An extensive overview of the evolution and progress made in the field of microstructures and nanostructures preparation using microfluidic techniques in recent times is presented and special attention should be paid to metal NPs developed through microfluidity routes.
Abstract: We present an extensive overview of the evolution and progress made in the field of microstructures and nanostructures preparation using microfluidic techniques in recent times. A microfluidic system creates particles that are within a narrow range of shape and size distribution. It enables controlling the shape, size and composition of nanomaterials (NMs) for various applications. A brief evaluation of the advantages of both droplet-based and continuous flow synthesis of nanoparticles (NPs) is discussed in detail and compared with the traditional wet chemical batch synthesis approach. Due to increasing applications of biosensing, nanobiotechnology, nanomedicine and diagnostics devices, special attention should be paid to metal NPs developed through microfluidic routes.
TL;DR: A review of the latest applications of the i-motif structure in the field of chemical analysis due to its sharp, fast and reversible pH-driven conformational changes is presented.
Abstract: Under the appropriate experimental conditions of pH and temperature, cytosine-rich segments in DNA or RNA sequences may produce a characteristic folded structure known as an i-motif. Besides its potential role in vivo, which is still under investigation, this structure has attracted increasing interest in other fields due to its sharp, fast and reversible pH-driven conformational changes. This "on/off" switch at molecular level is being used in nanotechnology and analytical chemistry to develop nanomachines and sensors, respectively. This paper presents a review of the latest applications of this structure in the field of chemical analysis.
TL;DR: This review highlights the progress that has been made in the development of fluorescent and luminescent probes (excluding nanoparticles) employed to monitor hydrogen peroxide under biological conditions and focused on probes developed in the past 10 years.
Abstract: Hydrogen peroxide is a well-established precursor of reactive oxygen and nitrogen species that are known to contribute to oxidative stress—the crucial factor responsible for the course of a wide range of phy-sicochemical processes as well as the genesis of various diseases, such as cancer and neurodegenerative disorders. Thus, the development of sensitive and selective methods for the detection and quantitative determination of hydrogen peroxide is of great importance in monitoring the in vivo production of that species and elucidating its biological functions. This review highlights the progress that has been made in the development of fluorescent and luminescent probes (excluding nanoparticles) employed to monitor hydrogen peroxide under biological conditions. Attention was focused on probes developed in the past 10 years.
TL;DR: This review covers current analytical techniques, instruments, and methodologies used in the analysis of fluoride in various matrices and explores chromatographic, spectroscopic, and electrochemical innovations appearing in the recent literature.
Abstract: This review covers current analytical techniques, instruments, and methodologies used in the analysis of fluoride in various matrices. Our comprehensive literature search showed that there is no recently published review article about analytical methodologies for fluoride. In this review, we explore chromatographic, spectroscopic, and electrochemical innovations appearing in the recent literature.
TL;DR: Several existing analytical techniques that are flexible and broad-based methods of analysis in different matrices are shown, such as thin-layer chromatography, microbiological assay, spectrophotometry, capillary electrophoresis (CE), and high-performance liquid chromatography (HPLC).
Abstract: The first-generation quinolones have their greatest potency against Gram-negative bacteria, but newly developed molecules have exhibited increased potency against Gram-positive bacteria, and existing agents are available with additional activity against anaerobic microorganisms. Norfloxacin is a broad-spectrum antimicrobial fluoroquinolone used against Gram-positive and Gram-negative organisms (aerobic organisms). There are different analytical methods available to determine norfloxacin applied in quality control of this medicine in order to ensure its effectiveness and safety. The authors present an overview of the fourth generation of quinolones, followed by the properties, applications, and analytical methods of norfloxacin. These results show several existing analytical techniques that are flexible and broad-based methods of analysis in different matrices. This article focuses on bionalytical and pharmaceutical quality-control applications, such as thin-layer chromatography, microbiological assay, spectrophotometry, capillary electrophoresis (CE), and high-performance liquid chromatography (HPLC).
TL;DR: It is concluded that fusidic acid has been used for decades and is indicated for the treatment of serious infections caused by Gram-positive microorganisms to this day, and is a hypoallergenic agent, has low toxicity, shows low resistance, and has no cross-resistance with other clinically used antibiotics.
Abstract: Fusidic acid, an antibiotic produced from the Fusidium coccineum fungus, belongs to the class of steroids, but has no corticosteroid effects. It is indicated for the treatment of infections caused by methicillin-resistant Staphylococcus aureus strains. The aim of this study was to search for the properties of fusidic acid published so far in the literature, as well as the methods developed for its determination in biological samples and pharmaceutical formulations. From the findings, we can conclude that fusidic acid has been used for decades and is indicated for the treatment of serious infections caused by Gram-positive microorganisms to this day. Furthermore, it is a hypoallergenic agent, has low toxicity, shows low resistance, and has no cross-resistance with other clinically used antibiotics. The analytical method of high-performance liquid chromatography has been widely used for determining fusidic acid, since it can reduce the cost and time of analysis, making it more viable for routine quality control in the pharmaceutical industry.
TL;DR: This review presents some of the most recent aspects related to antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays published in the period 2009–2014.
Abstract: This review presents some of the most recent aspects related to antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Taking into account the reactions involved, in the antioxidant activity determinations, the assays can be classified into two main types: hydrogen atom transfer reactions and electron transfer. This review focuses on analytical methods used for antioxidant activity assay, published in the period 2009-2014.
TL;DR: Potential and recent applications of mimetic enzymes in chemical sensors are reviewed in detail, and the outlook of profound development has been illustrated.
Abstract: The need to develop innovative and reformative approaches to synthesize chemical sensors has increased in recent years because of demands for selectivity, stability, and reproducibility. Mimetic enzymes provide an efficient and convenient method for chemical sensors. This review summarizes the application of mimetic enzymes in chemical sensors. Mimetic enzymes can be classified into five categories: hydrolases, oxidoreductases, transferases, isomerases, and induced enzymes. Potential and recent applications of mimetic enzymes in chemical sensors are reviewed in detail, and the outlook of profound development has been illustrated.
TL;DR: A novel approach for classification of flow analysis methods according to the conditions under which the mass transfer processes and chemical reactions take place in the flow mode: dispersion-convection flow methods and forced-conventus flow methods are suggested.
Abstract: We suggest a novel approach for classification of flow analysis methods according to the conditions under which the mass transfer processes and chemical reactions take place in the flow mode: dispersion-convection flow methods and forced-convection flow methods. The first group includes continuous flow analysis, flow injection analysis, all injection analysis, sequential injection analysis, sequential injection chromatography, cross injection analysis, multi-commutated flow analysis, multi-syringe flow injection analysis, multi-pumping flow systems, loop flow analysis, and simultaneous injection effective mixing flow analysis. The second group includes segmented flow analysis, zone fluidics, flow batch analysis, sequential injection analysis with a mixing chamber, stepwise injection analysis, and multi-commutated stepwise injection analysis. The offered classification allows systematizing a large number of flow analysis methods. Recent developments and applications of dispersion-convection flow methods and forced-convection flow methods are presented.
TL;DR: This review covers the recent development of micro-gas analyzers and focuses on injectors, stationary phases, column designs and detectors reported in the literature during the last three decades.
Abstract: Over 30 years, portable systems for fast and reliable gas analysis are at the core of both academic and industrial research. Miniaturized systems can be helpful in several domains. The way to make it possible is to miniaturize the whole gas chromatograph. Micro-system conception by etching silicon channel is well known. The main objective is to obtain similar or superior efficiencies to those obtained from laboratory chromatographs. However, stationary phase coatings on silicon surface and micro-detector conception with a low limit of detection remain a challenge. Developments are still in progress to offer a large range of stationary phases and detectors to meet the needs of analytical scientists. This review covers the recent development of micro-gas analyzers. It focuses on injectors, stationary phases, column designs and detectors reported in the literature during the last three decades. A list of commercially available micro-systems and their performances will also be presented.
TL;DR: This review outlines possibilities and limitations of various analytical methods for determination of endocrine-disruptor phthalate esters in various matrices, including somewhat neglected electroanalytical methods.
Abstract: Phthalates are endocrine disruptors frequently occurring in the general and industrial environment and in many industrial products. Moreover, they are also suspected of being carcinogenic, teratogenic, and mutagenic, and they show diverse toxicity profiles depending on their structures. The European Union and the United States Environmental Protection Agency (US EPA) have included many phthalates in the list of priority substances with potential endocrine-disrupting action. They are: dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), diethylhexyl phthalate (DEHP), di-iso-nonyl phthalate (DINP), di-iso-decyl phthalate (DIDP), di-n-decyl phthalate (DnDP), and dioctyl phthalate (DOP). There is an ever-increasing demand for new analytical methods suitable for monitoring different phthalates in various environmental, biological, and other matrices. Separation and spectrometric methods are most frequently used. However, modern electroanalytical methods can also play a useful role in this field because of their high sensitivity, reasonable selectivity, easy automation, and miniaturization, and especially low investment and running costs, which makes them suitable for large-scale monitoring. Therefore, this review outlines possibilities and limitations of various analytical methods for determination of endocrine-disruptor phthalate esters in various matrices, including somewhat neglected electroanalytical methods.
TL;DR: This review covers historical aspects of developments in the NMR field, its applications in chemical profiling, metabolomics, and quality control of plants and their derived medicines, foods, and other products.
Abstract: NMR spectroscopy has multidisciplinary applications, including excellent impact in metabolomics. The analytical capacity of NMR spectroscopy provides information for easy qualitative and quantitative assessment of both endogenous and exogenous metabolites present in biological samples. The complexity of a particular metabolite and its contribution in a biological system are critically important for understanding the functional state that governs the organism's phenotypes. This review covers historical aspects of developments in the NMR field, its applications in chemical profiling, metabolomics, and quality control of plants and their derived medicines, foods, and other products. The bottlenecks of NMR in metabolic profiling are also discussed, keeping in view the future scope and further technological interventions.
TL;DR: This article reviews the development of breath analysis and GC-based techniques in basic breath research, involving sampling methods, preconcentration methods, conventional GC- based techniques, and newly developed GC techniques for breath analysis.
Abstract: Breath analysis is a noninvasive diagnostic method that profiles a person's physical state by volatile organic compounds in the breath. It has huge potential in the field of disease diagnosis. In order to offer opportunities for practical applications, various GC-based techniques have been investigated for on-line breath analysis since GC is the most preferred technique for mixed gas separation. This article reviews the development of breath analysis and GC-based techniques in basic breath research, involving sampling methods, preconcentration methods, conventional GC-based techniques, and newly developed GC techniques for breath analysis. The combination of GC and newly developed detection techniques takes advantages of the virtues of each. In addition, portable GC or micro GC are poised to become field GC-based techniques in breath analysis. Challenges faced in GC-based techniques for breath analysis are discussed candidly. Effective cooperation of experts from different fields is urgent to promote the development of breath analysis.
TL;DR: This review focuses on the electroanalytical applications of MOFs between 2010 and 2014 years, which enable them to have potential applications in gas storage, catalysis, sensors, drug release, and separation.
Abstract: Metal-organic frameworks (MOFs) are attracting considerable attention because of their unique structural properties, such as high surface areas, tunable pore sizes, and open metal sites, which enable them to have potential applications in gas storage, catalysis, sensors, drug release, and separation. Also, MOFs can be fabricated and functionalized as electrochemically functional frameworks with perfect electrochemical properties and electrocatalytic activities. This review focuses on the electroanalytical applications of MOFs between 2010 and 2014 years.
TL;DR: This article focuses on metabolomics' mainstream research content and technical innovations such as determination methods for biologically active compounds and pays more attention to the future trends and various possibilities for metabolomics study.
Abstract: The advancement of omics technology has vigorously promoted the development of the life sciences; metabolomics in particular has emerged as a powerful tool that has a promising future in scientific research and clinical practice. As terminal products of complex biochemical networks, endogenous low-molecular-weight metabolites contain rich information about the physiological status of an individual or group of people. Also, this information has more practical significance in that we know "what happened" instead of "what might happen" to some degree. Rapid and accurate screening of metabolites on a large scale was beyond imagining in the past; however, benefiting from high-throughput technical means, the overall disturbance of metabolites induced by environmental stimulus or treatments can now be well analyzed. After appropriate bioinformatic analysis, clinically relevant biomarkers of a disease can be found, and an accurate and dynamic picture of metabolic disturbance that contributes to a phenotype of a certain organism can be constructed. Biomarkers can also reveal the general metabolic condition by pathways that correlate with disease progression, or even with the risk of certain diseases. Thus, as an indispensable part of the framework of systems biology, metabolomics has been widely used in, but not limited to, the fields of medical science, pharmaceuticals, botany, and microbiology. In this article, we focus on metabolomics' mainstream research content and technical innovations such as determination methods for biologically active compounds; further, we pay more attention to the future trends and various possibilities for metabolomics study.
TL;DR: This review is focused on the discovery and development of high-performance liquid Chromatography (HPLC) and gas chromatography (GC) with different detectors and the application of these methods for determination of these drugs in biological, environmental and pharmaceutical samples.
Abstract: The analysis of drugs in various biological fluids is an important criterion for the determination of the physiological performance of a drug. After sampling of the biological fluid, the next step in the analytical process is sample preparation. Sample preparation is essential for isolation of desired components from complex biological matrices and greatly influences their reliable and accurate determination. The complexity of biological fluids adds to the challenge of direct determination of the drug by chromatographic analysis, therefore demanding a sample preparation step that is often time consuming, tedious and frequently overlooked. However, direct online injection methods offer the advantage of reducing sample preparation steps and enabling effective pre-concentration and clean-up of biological fluids. These procedures can be automated and therefore reduce the requirements for handling potentially infectious biomaterial, improve reproducibility, and minimize sample manipulations and potential contamination. This review is focused on the discovery and development of high-performance liquid chromatography (HPLC) and gas chromatography (GC) with different detectors. The drugs covered in this review are antiepileptics, antidepressant (AD), and quinolones. The application of these methods for determination of these drugs in biological, environmental and pharmaceutical samples has also been discussed.
TL;DR: This review presents the problem of analytical studies of archeological materials with a special emphasis on organic residues, and current methods used in the determination of different organic compounds in archeological ceramics are presented.
Abstract: The analysis of the composition of organic residues present in pottery is an important source of information for historians and archeologists. Chemical characterization of the materials provides information on diets, habits, technologies, and original use of the vessels. This review presents the problem of analytical studies of archeological materials with a special emphasis on organic residues. Current methods used in the determination of different organic compounds in archeological ceramics are presented. Particular attention is paid to the procedures of analysis of archeological ceramic samples used before gas chromatography-mass spectrometry. Advantages and disadvantages of different extraction methods and application of proper quality assurance/quality control procedures are discussed.
TL;DR: This review presents coupled techniques such as separation through the liquid membrane coupled with flow injection analysis, as well as advantages of using liquid membranes in laboratory studies.
Abstract: This review discusses the results of research in the use of bulk liquid membranes in separation processes and preconcentration for analytical purposes. It includes some theoretical aspects, definitions, types of liquid membranes, and transport mechanism, as well as advantages of using liquid membranes in laboratory studies. These concepts are necessary to understand fundamental principles of liquid membrane transport. Due to the multiple advantages of liquid membranes several studies present analytical applications of the transport through liquid membranes in separation or preconcentration processes of metallic cations and some organic compounds, such as phenol and phenolic derivatives, organic acids, amino acids, carbohydrates, and drugs. This review presents coupled techniques such as separation through the liquid membrane coupled with flow injection analysis.
TL;DR: The potential of novel materials designed and used for selective binding of chromium species is shown and the progress in miniaturization of measurement systems is presented.
Abstract: The biological activity of Cr(III) and Cr(VI) species, their chemical behavior, and toxic effects are dissimilar. The speciation analysis of Cr(III) and Cr(VI) in environmental matrices is then of great importance and much research has been devoted to this area. This review presents recent developments in on-line speciation analysis of chromium in such samples. Flow systems have proved to be excellent tools for automation of sample pretreatment, separation/preconcentration of chromium species, and their detection by various instrumental techniques. Analytical strategies used in chromium speciation analysis discussed in this review are divided into categories based on selective extraction/separation of chromium species on solid sorbents and liquid-liquid extraction of chromium species. The most popular strategy is that based on solid-phase extraction. Therefore, this review shows the potential of novel materials designed and used for selective binding of chromium species. The progress in miniaturization of measurement systems is also presented.
TL;DR: This review focuses on the progress that has been made in recent years in the development of fluorescent and luminescent probes employed to monitor hydroxyl radical concentrations under biological conditions.
Abstract: Detection and quantitative determination in biological media of the hydroxyl radical are of great importance due to the role this radical plays in many physiological and pathological processes. This review focuses on the progress that has been made in recent years in the development of fluorescent and luminescent probes employed to monitor hydroxyl radical concentrations under biological conditions.