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Selected
papers from the latest issue:
Light-scattering colloquium continues to shine
17 December 2012,
03:21:54
Available online 13 December
2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
Chemiluminescent systems generating reactive oxygen species from the decomposition of hydrogen peroxide and their analytical applications
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
Chemiluminescent systems generating reactive oxygen species from the decomposition of hydrogen peroxide and their analytical applications
17 December 2012,
03:21:54
Available online 10 December
2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
This review extensively covers information on chemiluminescence (CL)-reaction systems, which generate reactive oxygen species (ROSs) [e.g., superoxide radicals, singlet oxygen, hydroxyl radicals and peroxynitrite] from the decomposition of hydrogen peroxide and their analytical applications. We discuss the advantages and the limitations of applying CL methods to routine analysis.
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
This review extensively covers information on chemiluminescence (CL)-reaction systems, which generate reactive oxygen species (ROSs) [e.g., superoxide radicals, singlet oxygen, hydroxyl radicals and peroxynitrite] from the decomposition of hydrogen peroxide and their analytical applications. We discuss the advantages and the limitations of applying CL methods to routine analysis.
Highlights
► Chemiluminescent reaction systems generate reactive oxygen species (ROSs). ► Reactive oxygen species (ROSs) can detection of various analytes. ► Analyte structure is related to chemiluminescence intensity. ► Chemiluminescence methods have high sensitivity and a wide linear range. ► Chemiluminescence methods may be more sensitive and more selective.On-line bacteriological detection in water
17 December 2012,
03:21:54
Available online 7 December
2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
Microorganism contamination is a permanent concern in a wide range of fields, including the water-treatment, food and pharmaceutical industries, in which fast detection is critical to prevent microbial outbreaks. In water monitoring, current procedures for water-quality analysis are based on periodic sampling and detection by culture methods, which are slow, requiring 24–48 h for completion, so that, when first results reach the decision-takers and trigger an alarm, significant time has already passed and the population may have been exposed to a health hazard There is a need for rapid, reliable detection of contaminants in a broad spectrum of water-management situations. For real-time detection, on-line monitoring seems to be the ideal approach, but the need to adjust the available techniques to autonomous operation and the optimization of response time are substantial challenges. This review presents the findings of an identification study about the state-of-the-art of technologies and commercial devices for on-line biomonitoring of water quality, specifically for the detection of fecal contamination. We also include studies dealing with verification or use of these devices.
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
Microorganism contamination is a permanent concern in a wide range of fields, including the water-treatment, food and pharmaceutical industries, in which fast detection is critical to prevent microbial outbreaks. In water monitoring, current procedures for water-quality analysis are based on periodic sampling and detection by culture methods, which are slow, requiring 24–48 h for completion, so that, when first results reach the decision-takers and trigger an alarm, significant time has already passed and the population may have been exposed to a health hazard There is a need for rapid, reliable detection of contaminants in a broad spectrum of water-management situations. For real-time detection, on-line monitoring seems to be the ideal approach, but the need to adjust the available techniques to autonomous operation and the optimization of response time are substantial challenges. This review presents the findings of an identification study about the state-of-the-art of technologies and commercial devices for on-line biomonitoring of water quality, specifically for the detection of fecal contamination. We also include studies dealing with verification or use of these devices.
Highlights
► Real-time detection of pathogens versus grab sampling plus laboratory analysis. ► Techniques for microbial detection identified and assessed for on-line potential. ► Market review of instruments for monitoring of fecal contamination of waters. ► Instruments were applied to water analysis and their performance reported.Dispersive liquid-liquid microextraction for chemical speciation and determination of ultra-trace concentrations of metal ions
17 December 2012,
03:21:54
Available online 7 December
2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
Recent years have seen an upsurge of interest in developing a low-cost, easy-to-operate, reliable preconcentration technique for precise determination of ultra-trace concentrations of metal ions in aqueous matrices. Dispersive liquid-liquid microextraction (DLLME) is a novel sample-preparation technique offering high enrichment factors from low volumes of water samples. We compare DLLME, cloud-point extraction and other microextraction techniques. We also highlight the current best practices for analysis and chemical speciation of metal ions in highly salted media. We strongly recommend the stripping voltammetric technique at modified electrodes coupled to DLLME and other microextraction techniques to develop low-cost, precise methods for ultra-trace concentrations of metal ions in biological and environmental samples.
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
Recent years have seen an upsurge of interest in developing a low-cost, easy-to-operate, reliable preconcentration technique for precise determination of ultra-trace concentrations of metal ions in aqueous matrices. Dispersive liquid-liquid microextraction (DLLME) is a novel sample-preparation technique offering high enrichment factors from low volumes of water samples. We compare DLLME, cloud-point extraction and other microextraction techniques. We also highlight the current best practices for analysis and chemical speciation of metal ions in highly salted media. We strongly recommend the stripping voltammetric technique at modified electrodes coupled to DLLME and other microextraction techniques to develop low-cost, precise methods for ultra-trace concentrations of metal ions in biological and environmental samples.
Highlights
► Dispersive liquid-liquid microextraction (DLLME) applied, even in high salt liquids. ► Comparison of applications of sample-extraction techniques. ► Limitations of dispersive liquid-liquid microextraction (DLLME) coupled for analysis. ► Outlook for future applications of dispersive liquid-liquid microextraction (DLLME).
17 December 2012,
03:21:54
Available online 4 December
2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
The increasing use of metallic nanoparticles (MNPs) in a wide variety of applications has led to an urgent need to evaluate the impact of these new materials on human health and the environment. To date, the potential toxicity of MNPs and their interaction mechanisms with cells and living organisms have not been fully addressed. In this article, we discuss the different bioanalytical strategies that have been used for this purpose. We consider different methods aiming to evaluate cellular uptake and localization in cells and tissues, and in-vitro methods for the study of the toxicity induced by MNPs, considering different toxicity markers and high-throughput approaches for the identification of specific targets involved in the cell-MNP interaction. We also discuss special strategies related to the use of animal models to assess in-vivo toxicity of MNPs.
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
The increasing use of metallic nanoparticles (MNPs) in a wide variety of applications has led to an urgent need to evaluate the impact of these new materials on human health and the environment. To date, the potential toxicity of MNPs and their interaction mechanisms with cells and living organisms have not been fully addressed. In this article, we discuss the different bioanalytical strategies that have been used for this purpose. We consider different methods aiming to evaluate cellular uptake and localization in cells and tissues, and in-vitro methods for the study of the toxicity induced by MNPs, considering different toxicity markers and high-throughput approaches for the identification of specific targets involved in the cell-MNP interaction. We also discuss special strategies related to the use of animal models to assess in-vivo toxicity of MNPs.
Highlights
► A review on the different methods for evaluating the toxicity of MNPs is presented. ► Methods. ► for cellular uptake and localization are discussed. ► In-vitro cytotoxicity assays for assessing the toxicity of MNPs are described. ► Characteristics of the in-vivo models used for toxicity assays are reviewed.Results for PCDDs/PCDFs and dl-PCBs in the First Round of the Biennial Global Interlaboratory Assessment on Persistent Organic Pollutants
17 December 2012,
03:21:54
Available online 3 December
2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
The first worldwide interlaboratory study on persistent organic pollutants (POPs) under the Stockholm Convention was organized in the Asian/Pacific, South American and African regions during 2009–11. A relatively large number of laboratories reported data for the PCDD/PCDF and dioxin-like PCBs, especially in the Asian region. Within the Asian region, several participants used high-resolution GC/high-resolution MS systems optimized for dioxin analysis. High-resolution capacity is limited for the Latin America and African regions, although recently several new laboratories for dioxins have started in the Latin American region.
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry
The first worldwide interlaboratory study on persistent organic pollutants (POPs) under the Stockholm Convention was organized in the Asian/Pacific, South American and African regions during 2009–11. A relatively large number of laboratories reported data for the PCDD/PCDF and dioxin-like PCBs, especially in the Asian region. Within the Asian region, several participants used high-resolution GC/high-resolution MS systems optimized for dioxin analysis. High-resolution capacity is limited for the Latin America and African regions, although recently several new laboratories for dioxins have started in the Latin American region.
Highlights
► The first assessment of the quality of dioxin analysis in developing countries. ► A critical evaluation of the statistical methods used to validate QA/QC data. ► A comparison of the analytical variation with the international literature. ► The first assessment of regional quality in both developed and developing regions.
17 December 2012,
03:21:54
December 2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry, Volume 41
The generation of calibrated vapor samples of explosives compounds remains a challenge due to the low vapor pressures of explosives, adsorption of explosives on container and tubing walls, and the requirement to manage (typically) multiple temperature zones as the vapor is generated, diluted, and delivered. Methods that have been described to generate vapors can be classified as continuous or pulsed-flow vapor generators. Vapor sources for continuous-flow generators are typically explosives compounds supported on a solid support, or compounds contained in a permeation or diffusion device. Sources are held at elevated isothermal temperatures. Similar sources can be used for pulsed vapor generators; however, pulsed systems may also use injection of solutions onto heated surfaces with generation of both solvent and explosives vapors, transient peaks from a gas chromatograph, or vapors generated by programmed thermal desorption. This article reviews vapor-generator approaches with emphasis on the method of generating the vapors and on practical aspects of vapor dilution and handling. In addition, a gas chromatograph system with two ovens that is configurable with up to four heating ropes is proposed, and could serve as a single integrated platform for explosives-vapor generation and device testing. We also discuss issues related to standards, calibration, and safety.
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry, Volume 41
The generation of calibrated vapor samples of explosives compounds remains a challenge due to the low vapor pressures of explosives, adsorption of explosives on container and tubing walls, and the requirement to manage (typically) multiple temperature zones as the vapor is generated, diluted, and delivered. Methods that have been described to generate vapors can be classified as continuous or pulsed-flow vapor generators. Vapor sources for continuous-flow generators are typically explosives compounds supported on a solid support, or compounds contained in a permeation or diffusion device. Sources are held at elevated isothermal temperatures. Similar sources can be used for pulsed vapor generators; however, pulsed systems may also use injection of solutions onto heated surfaces with generation of both solvent and explosives vapors, transient peaks from a gas chromatograph, or vapors generated by programmed thermal desorption. This article reviews vapor-generator approaches with emphasis on the method of generating the vapors and on practical aspects of vapor dilution and handling. In addition, a gas chromatograph system with two ovens that is configurable with up to four heating ropes is proposed, and could serve as a single integrated platform for explosives-vapor generation and device testing. We also discuss issues related to standards, calibration, and safety.
Highlights
► Methods to generate vapors of explosives compounds are reviewed. ► Generators deliver either a known concentration or a known mass of vapor. ► Vapor generators are classified as either continuous or pulsed flow. ► Issues of standards, calibration and safety are also discussed.Ionic liquids in solid-phase extraction
17 December 2012,
03:21:54
December 2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry, Volume 41
Supported ionic-liquid phases (SILPs), which favorably combine the properties of ionic liquids (ILs) with the advantages of solid supports, were presented in 2009 as an alternative material for solid-phase extraction (SPE). Since then, the number of SILPs used as SPE materials has increased and the results are promising. This report covers various aspects of SILPs: the procedure for their preparation, which clearly depends on the support (based on silica or polymer) where the ILs are immobilized; their interaction mechanisms, which are strongly linked to the SPE protocol and the target analytes; and, their fields of application with a number of selected examples. This is the first review that exclusively describes all SILPs that have been developed to date as sorbents in SPE.
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry, Volume 41
Supported ionic-liquid phases (SILPs), which favorably combine the properties of ionic liquids (ILs) with the advantages of solid supports, were presented in 2009 as an alternative material for solid-phase extraction (SPE). Since then, the number of SILPs used as SPE materials has increased and the results are promising. This report covers various aspects of SILPs: the procedure for their preparation, which clearly depends on the support (based on silica or polymer) where the ILs are immobilized; their interaction mechanisms, which are strongly linked to the SPE protocol and the target analytes; and, their fields of application with a number of selected examples. This is the first review that exclusively describes all SILPs that have been developed to date as sorbents in SPE.
Highlights
► Review of supported ionic-liquid phase (SILPs) used in solid-phase extraction (SPE). ► We review the different preparation approaches to support ionic liquids. ► We discuss the interaction mechanisms aroused on supported ionic-liquid phase (SILPs). ► Applications of supported ionic-liquid phase (SILPs) in solid-phase extraction (SPE).Analytical strategies for characterization and validation of functional dairy foods
17 December 2012,
03:21:54
December 2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry, Volume 41
Functional foods (FFs) are food products to be consumed as part of a balanced diet. They provide physiological benefits or reduce the risk of chronic disease beyond basic nutritional functions. Functional foods containing probiotics and/or prebiotics have gained much interest in recent years due to their health-promoting capacity. The main objective of this review is to discuss the analytical strategies that have been used to validate FFs associated with dairy products containing probiotics and/or prebiotics. In these products, the biochemical events, carried out by enzymes of different sources (milk, bacteria, rennet) leading to the transformation of milk to diverse products (e.g., yoghurt and cheese), are glycolysis, proteolysis and lipolysis. We present the analytical methodologies used to study the microbial probiotic flora and to evaluate the biochemical transformations, the associated functionality in terms of intestinal microbiome and the safety of such FFs. We address the analytical figures of merit. We cover the advantages and the disadvantages of such analytical methodologies and comment on future applications and potential research interest within this field.
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry, Volume 41
Functional foods (FFs) are food products to be consumed as part of a balanced diet. They provide physiological benefits or reduce the risk of chronic disease beyond basic nutritional functions. Functional foods containing probiotics and/or prebiotics have gained much interest in recent years due to their health-promoting capacity. The main objective of this review is to discuss the analytical strategies that have been used to validate FFs associated with dairy products containing probiotics and/or prebiotics. In these products, the biochemical events, carried out by enzymes of different sources (milk, bacteria, rennet) leading to the transformation of milk to diverse products (e.g., yoghurt and cheese), are glycolysis, proteolysis and lipolysis. We present the analytical methodologies used to study the microbial probiotic flora and to evaluate the biochemical transformations, the associated functionality in terms of intestinal microbiome and the safety of such FFs. We address the analytical figures of merit. We cover the advantages and the disadvantages of such analytical methodologies and comment on future applications and potential research interest within this field.
Highlights
► Functional dairy foods (FDFs) play important roles in promoting health and well-being. ► Monitoring bacteria and biochemical events in functional dairy foods (FDFs). ► Molecular and non-molecular methods are complementary in microbiota characterization. ► Advanced biochemical analyses have enabled probing for bioactive compounds. ► Omics technologies assess impact of functional dairy foods (FDFs) on gut microbiome.Applications of aptamer affinity chromatography
17 December 2012,
03:21:54
December 2012
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry, Volume 41
Nucleic-acid aptamers are promising affinity ligands in affinity chromatography. The relatively small size of aptamers and their ease of chemical conjugation to chromatographic supports make high-density aptamer columns useful for affinity separation. Other key features of aptamers pertinent to their applications in affinity chromatography include their good stability, high purity, and desirable binding properties. This article describes the current status of aptamer affinity chromatography (AAC) in separation, extraction, purification and detection of targets of interest, ranging from small molecules to proteins and cells. Further development and applications of AAC can benefit from the recent advances in aptamer-selection techniques, chromatographic stationary-phase supports, nanomaterials and microfluidic manipulations.
Publication year: 2012
Source:TrAC Trends in Analytical Chemistry, Volume 41
Nucleic-acid aptamers are promising affinity ligands in affinity chromatography. The relatively small size of aptamers and their ease of chemical conjugation to chromatographic supports make high-density aptamer columns useful for affinity separation. Other key features of aptamers pertinent to their applications in affinity chromatography include their good stability, high purity, and desirable binding properties. This article describes the current status of aptamer affinity chromatography (AAC) in separation, extraction, purification and detection of targets of interest, ranging from small molecules to proteins and cells. Further development and applications of AAC can benefit from the recent advances in aptamer-selection techniques, chromatographic stationary-phase supports, nanomaterials and microfluidic manipulations.
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