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papers from the latest issue:
Terahertz spectral analysis
10 January 2013,
07:58:39
Available online 8 January
2013
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry
Terahertz (THz) spectroscopy is a well-established technique, and recent progress in technology demonstrated that it is useful for fundamental research and industrial applications. Applications (e.g., imaging, non-destructive testing, and quality control) are about to be transferred to industry, following improvements derived from basic research. Since chemometrics is routinely applied to infrared spectroscopy, we discuss the advantages of applying chemometrics to THz spectroscopy. We illustrate different analytical procedures. We conclude that advanced data processing is the key to validating THz spectroscopy as a reliable, routine analytical technique.
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry
Terahertz (THz) spectroscopy is a well-established technique, and recent progress in technology demonstrated that it is useful for fundamental research and industrial applications. Applications (e.g., imaging, non-destructive testing, and quality control) are about to be transferred to industry, following improvements derived from basic research. Since chemometrics is routinely applied to infrared spectroscopy, we discuss the advantages of applying chemometrics to THz spectroscopy. We illustrate different analytical procedures. We conclude that advanced data processing is the key to validating THz spectroscopy as a reliable, routine analytical technique.
Highlights
► We discuss the advantages of using chemometrics in terahertz spectroscopy. ► We demonstrate the complementary nature of information from terahertz spectroscopy. ► Chemometrics is key to terahertz spectroscopy being a reliable analytical technique.Nanoporous anodic aluminum oxide for chemical sensing and biosensors
10 January 2013,
07:58:39
Available online 3 January
2013
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry
Nanoporous anodic aluminum oxide (AAO) has become one of the most popular materials with potential applications in numerous areas, including molecular separation, catalysis, energy generation and storage, electronics, photonics, sensing, drug delivery, and template synthesis. The fabrication of AAO is based on simple, cost-effective self-ordering anodization of aluminum, which yields vertically-aligned, highly-ordered nanoporous structures. Due to its unique optical and electrochemical properties, nanoporous AAO has been extensively explored as a platform for developing inexpensive, portable sensing and biosensing devices. This article reviews AAO-based sensing and biosensing technologies, highlighting key examples of different detection concepts and device performance. We conclude with a perspective on the exciting opportunities for further developments in this research field.
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry
Nanoporous anodic aluminum oxide (AAO) has become one of the most popular materials with potential applications in numerous areas, including molecular separation, catalysis, energy generation and storage, electronics, photonics, sensing, drug delivery, and template synthesis. The fabrication of AAO is based on simple, cost-effective self-ordering anodization of aluminum, which yields vertically-aligned, highly-ordered nanoporous structures. Due to its unique optical and electrochemical properties, nanoporous AAO has been extensively explored as a platform for developing inexpensive, portable sensing and biosensing devices. This article reviews AAO-based sensing and biosensing technologies, highlighting key examples of different detection concepts and device performance. We conclude with a perspective on the exciting opportunities for further developments in this research field.
Highlights
► The structure, fabrication and properties of nanoporous alumina are described. ► Nanoporous alumina possess many advantages for sensing and biosensing. ► Recent advances in optical sensors and biosensors are highlighted. ► Recent developments of electrochemical sensors and biosensors are presented.
10 January 2013,
07:58:39
Available online 3 January
2013
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry
Nowadays, control of pesticide residues (PRs) in food must be conducted in accredited laboratories, using advanced analytical methods that achieve the low maximum residue levels established in regulations. In addition, laboratories have to meet customers’ requirements in terms of time and cost of analysis. Consequently, PR analysis (PRA) requires non-laborious sample treatments, in order to increase sample throughput, in combination with gas or liquid chromatography coupled with tandem mass spectrometry. However, it is necessary to consider the economics of the process to ensure the viability of PRA laboratories. The price of this type of analysis has not increased in the past decade, and the operational costs, mainly equipment and personnel, have increased significantly. In this article, we provide a methodology to assess the effective capacity and the break-even point of a PRA laboratory, and the tools to evaluate the profitability of acquisitions of new equipment.
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry
Nowadays, control of pesticide residues (PRs) in food must be conducted in accredited laboratories, using advanced analytical methods that achieve the low maximum residue levels established in regulations. In addition, laboratories have to meet customers’ requirements in terms of time and cost of analysis. Consequently, PR analysis (PRA) requires non-laborious sample treatments, in order to increase sample throughput, in combination with gas or liquid chromatography coupled with tandem mass spectrometry. However, it is necessary to consider the economics of the process to ensure the viability of PRA laboratories. The price of this type of analysis has not increased in the past decade, and the operational costs, mainly equipment and personnel, have increased significantly. In this article, we provide a methodology to assess the effective capacity and the break-even point of a PRA laboratory, and the tools to evaluate the profitability of acquisitions of new equipment.
Highlights
► Economics of pesticide-residue control in vegetables in routine laboratories. ► Legal and customer demands restrict productivity of a pesticide-residue laboratory. ► Fixed costs of pesticide-residue analysis are very high compared to variable costs. ► Methodology to assess effective capacity and break-even point of a laboratory.
10 January 2013,
07:58:39
January 2013
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
Since the first coupling of laser-ablation inductively-coupled plasma to mass spectrometry (LA-ICP-MS) in 1985, applications of this analytical technique in various scientific fields have been developed. LA-ICP-MS is an elemental and isotopic microanalytical technique that is increasingly used for routine analysis in forensic laboratories around the world due to its great discriminating power between samples and its capacity for analyzing solid evidence of small size. In addition, its quasi-non-destructive character is especially welcome for this type of sample. The main forensic applications of LA-ICP-MS have been developed for glass and paint samples. However, applications to other samples have also been reported [e.g., documents (ink and paper), fibers, cannabis, gems, Australian ocher and porcelain, brick stones, and gold and silver]. In the forensic field, the adjustment of instrumental analytical parameters, the study of interferences produced by fractionation and polyatomic ions, and the statistical treatment of data are considered of great importance. This review is intended as a practical, useful guide to help forensic chemists incorporate this attractive, powerful technique into their laboratories.
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
Since the first coupling of laser-ablation inductively-coupled plasma to mass spectrometry (LA-ICP-MS) in 1985, applications of this analytical technique in various scientific fields have been developed. LA-ICP-MS is an elemental and isotopic microanalytical technique that is increasingly used for routine analysis in forensic laboratories around the world due to its great discriminating power between samples and its capacity for analyzing solid evidence of small size. In addition, its quasi-non-destructive character is especially welcome for this type of sample. The main forensic applications of LA-ICP-MS have been developed for glass and paint samples. However, applications to other samples have also been reported [e.g., documents (ink and paper), fibers, cannabis, gems, Australian ocher and porcelain, brick stones, and gold and silver]. In the forensic field, the adjustment of instrumental analytical parameters, the study of interferences produced by fractionation and polyatomic ions, and the statistical treatment of data are considered of great importance. This review is intended as a practical, useful guide to help forensic chemists incorporate this attractive, powerful technique into their laboratories.
Highlights
► A practical guide to introduce and help forensic scientists in the use of LA-ICP-MS. ► LA-ICP-MS is a versatile tool for the chemical investigation of physical evidence. ► The review is based on the most important articles published in the past 12years.The vapor pressures of explosives
10 January 2013,
07:58:39
January 2013
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
The vapor pressures (VPs) of many explosive compounds are extremely low, so determining accurate values proves difficult. Many researchers, using a variety of methods, have measured and reported the VPs of explosive compounds at single temperatures, or as a function of temperature using VP equations. There are large variations in reported VPs for many of these compounds, and some errors exist within individual papers. This article provides a review of explosive VPs and describes the methods used to determine them. We have compiled primary VP relationships traceable to the original citations and include the temperature ranges for which they have been determined. Corrected values are reported as needed and described in the text. In addition, after critically examining the available data, we calculate and tabulate VPs at 25°C.
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
The vapor pressures (VPs) of many explosive compounds are extremely low, so determining accurate values proves difficult. Many researchers, using a variety of methods, have measured and reported the VPs of explosive compounds at single temperatures, or as a function of temperature using VP equations. There are large variations in reported VPs for many of these compounds, and some errors exist within individual papers. This article provides a review of explosive VPs and describes the methods used to determine them. We have compiled primary VP relationships traceable to the original citations and include the temperature ranges for which they have been determined. Corrected values are reported as needed and described in the text. In addition, after critically examining the available data, we calculate and tabulate VPs at 25°C.
Highlights
► A review of explosive vapor pressures and the methods used to determine them. ► Vapor-pressure relationships are tabulated values traceable to original citations. ► Reported are calculated vapor pressures at 25°C. ► Calculated values and their averages for compounds are critically discussed.Towards better understanding of feature-selection or reduction techniques for Quantitative Structure–Activity Relationship models
10 January 2013,
07:58:39
January 2013
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
A Quantitative Structure–Activity Relationship (QSAR) is a linear or non-linear model, which relates variations in molecular descriptors to variations in the biological activity of a series of active and/or inactive molecules. For this article, different feature-selection or reduction methods were all coupled with Partial Least Squares (PLS) modeling during the selection of features. A PLS model was also built with the entire set of molecular descriptors and was used as a reference to check the reliability and the performance of the different feature-selection methods. To evaluate the ability of the different feature-selection methods, they were performed on two data sets.
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
A Quantitative Structure–Activity Relationship (QSAR) is a linear or non-linear model, which relates variations in molecular descriptors to variations in the biological activity of a series of active and/or inactive molecules. For this article, different feature-selection or reduction methods were all coupled with Partial Least Squares (PLS) modeling during the selection of features. A PLS model was also built with the entire set of molecular descriptors and was used as a reference to check the reliability and the performance of the different feature-selection methods. To evaluate the ability of the different feature-selection methods, they were performed on two data sets.
Highlights
► Molecular structure determined and conformational analysis performed. ► Molecular descriptors are calculated based on above structure determination. ► Several feature-selection methods are applied and linked to PLS modeling technique. ► QSAR models were built with PLS and MLR (when only a few descriptors were selected). ► The Replacement Method was found to select few variables and led to good models.Aqueous normal-phase chromatography using silica-hydride-based stationary phases
10 January 2013,
07:58:39
January 2013
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
Aqueous normal-phase chromatography utilizing silica-hydride-based stationary phases provides unique selectivities for the separation of polar and non-polar compounds and offers new avenues to solve difficult analytical separations. By varying the amount of water in the mobile phase, all silica-hydride-based separation materials can operate in the reversed-phase mode, the normal-phase mode or, in some instances, a combination of both. This review describes some of the fundamental properties of silica-hydride materials and applications that encompass a broad range of separation challenges. Moreover, exemplars are provided that illustrate many of the prominent features that lead to the selection of such stationary phases for solving a particular analytical problem.
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
Aqueous normal-phase chromatography utilizing silica-hydride-based stationary phases provides unique selectivities for the separation of polar and non-polar compounds and offers new avenues to solve difficult analytical separations. By varying the amount of water in the mobile phase, all silica-hydride-based separation materials can operate in the reversed-phase mode, the normal-phase mode or, in some instances, a combination of both. This review describes some of the fundamental properties of silica-hydride materials and applications that encompass a broad range of separation challenges. Moreover, exemplars are provided that illustrate many of the prominent features that lead to the selection of such stationary phases for solving a particular analytical problem.
Highlights
► The unique separation properties of silica-hydride materials are described. ► Silica-hydride materials can retain both polar and non-polar compounds. ► Applications to pharmaceuticals, peptides and polar metabolites are presented.Analytical strategies for the characterization of therapeutic monoclonal antibodies
10 January 2013,
07:58:39
January 2013
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
Recombinant monoclonal antibodies (mAbs) have become particularly relevant for the treatment of autoimmune diseases or cancers. Because of their inherent complexity and for safety reasons, there is a need to develop powerful analytical methods to provide detailed characterizations of mAbs. The aim of the present review is to detail the state-of-the-art of analytical strategies for mAb characterization. It focuses on the most important separation techniques used in this field, specifically, the chromatographic and electrophoretic approaches and their combination with mass spectrometry (MS). Thanks to recent improvements in separation science and MS devices, mAbs can be analyzed more easily. However, there is still a need to find new approaches that avoid adsorption issues.
Publication year: 2013
Source:TrAC Trends in Analytical Chemistry, Volume 42
Recombinant monoclonal antibodies (mAbs) have become particularly relevant for the treatment of autoimmune diseases or cancers. Because of their inherent complexity and for safety reasons, there is a need to develop powerful analytical methods to provide detailed characterizations of mAbs. The aim of the present review is to detail the state-of-the-art of analytical strategies for mAb characterization. It focuses on the most important separation techniques used in this field, specifically, the chromatographic and electrophoretic approaches and their combination with mass spectrometry (MS). Thanks to recent improvements in separation science and MS devices, mAbs can be analyzed more easily. However, there is still a need to find new approaches that avoid adsorption issues.
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