Grafting of cellulose by ring-opening polymerisation – A review

In this review, homogeneous and heterogeneous grafting from cellulose and cellulose derivatives by ring-opening polymerisation (ROP) are reported. Cellulose is biorenewable and biodegradable as well as a stiff material with a relatively low specific weight, foreseen to be an excellent replacement for synthetic materials. By utilising ROP of monomers such as ε-caprolactone or l-lactide from cellulose, composite materials with new and/or improved properties can be obtained. Grafting of solid cellulose substrates, such as cotton, microfibrillated cellulose (MFC) or cellulose nanocrystals, renders cellulose that can easily be dispersed into polymer matrices and may be used as reinforcing elements to improve mechanical and/or barrier properties of biocomposites. A surface grafted polymer can also tailor the interfacial properties between a matrix and the fibrillar structure of cellulose. When derivatives of cellulose are grafted with polymers in homogenous media, amphiphilic materials with interesting properties can be achieved, anticipated to be utilised for applications such as encapsulation and release.     

Electrical field-induced extraction and separation techniques: Promising trends in analytical chemistry – A review

Sample preparation is an important issue in analytical chemistry, and is often a bottleneck in chemical analysis. So, the major incentive for the recent research has been to attain faster, simpler, less expensive, and more environmentally friendly sample preparation methods. The use of auxiliary energies, such as heat, ultrasound, and microwave, is one of the strategies that have been employed in sample preparation to reach the above purposes. Application of electrical driving force is the current state-of-the-art, which presents new possibilities for simplifying and shortening the sample preparation process as well as enhancing its selectivity. The electrical driving force has scarcely been utilized in comparison with other auxiliary energies. In this review, the different roles of electrical driving force (as a powerful auxiliary energy) in various extraction techniques, including liquid-, solid-, and membrane-based methods, have been taken into consideration. Also, the references have been made available, relevant to the developments in separation techniques and Lab-on-a-Chip (LOC) systems. All aspects of electrical driving force in extraction and separation methods are too specific to be treated in this contribution. However, the main aim of this review is to provide a brief knowledge about the different fields of analytical chemistry, with an emphasis on the latest efforts put into the electrically assisted membrane-based sample preparation systems. The advantages and disadvantages of these approaches as well as the new achievements in these areas have been discussed, which might be helpful for further progress in the future.     

Ultrasound-assisted multicomponent synthesis of heterocycles in water – A review

Ultrasound-assisted multicomponent reactions in water are great implements for the development of bioactive compounds. The methodologies for the synthesis of different heterocyclic molecules have acquired enormous attention. Many such techniques are energy-intensive and associated with hazardous chemicals, solvents, expensive work-ups. Low yields and multi-step schemes generate huge organic waste. Hence, researchers thus focussed on benign and eco-friendly techniques to assemble heterocyclic analogs and drug molecules. The ultrasound-assisted synthesis of the target organic moieties frequently facilitates higher product yields than other methodologies. This review is focused on ultrasound-aided multicomponent reactions for synthesizing varied nitrogen-, oxygen-, and sulfur-containing heterocyclic compounds using water as the solvent. The advantages and limitations with respect to yields and reaction conditions are discussed. This evaluation covered the literature reports from 2014 to date.     

Taylor dispersion analysis of metallic-based nanoparticles – A short review

Taylor dispersion analysis (TDA) is an interesting tool for nanoparticle (NP) size determination, feasible using simple capillary electrophoresis apparatus. Based upon the radial diffusion of analytes upon a laminar stream, the diffusion coefficient of species is easily estimable. Moreover, TDA is generally more adequate than conventional dynamic light scattering methodologies as it is less dependent on the polydispersity of the sample, leading to accurate measurement and reliable results. This review provides every paper mentioning the use of TDA for metallic-based NPs size determination. Diverse strategies for the detection of metallic NPs (like UV–visible and inductively coupled plasma–mass spectrometry – ICP–MS – for instance) and interpretation of the Taylorgrams are discussed. Based upon the literature, advices on future prospects are also indicated, especially for the comparison of TDA results with other classical techniques.     

Ionic liquids in separations of azeotropic systems – A review

Efforts to make existing separation methods more efficient and eco-friendly may get a boost from the use of a relatively new class of compounds known as ionic liquids (ILs). The separation of azeotropic mixtures has conventionally been one of the most challenging tasks in industrial processes due to the fact that their separation by simple distillation is basically impossible.This paper provides a critical review of methods using ILs as azeotrope breakers. Three separation processes were addressed: liquid–liquid extraction, extractive distillation, and supported liquid membranes. We examine the azeotrope breaking potential of ILs and compare their performance to that of conventional solvents. A systematic analysis of the influence of the structure of ILs on their azeotrope breaking capacity contributes to the establishment of guidelines for selecting the most suitable ILs for the separation of specific azeotropic mixtures.     

Certified reference materials in analytical chemistry – A century of NIST contribution

Over the course of its first 100 years, the National Institute of Standards and Technology (NIST) has made numerous contributions to advancing the science and practice of analytical chemistry. Contributions to fundamental constants and reference data, such as determination of the Faraday, Avagadro’s number, and atomic masses, began at almost the beginning of the new institution when it was formed in 1901. Instrumentation development, improvement, and reproducible methods for its use have also been an important part of the NIST effort. This paper will describe what may be the organization’s most important and certainly its most unique contribution; namely, certified reference materials. Ultimately these certified reference materials would become known at NIST as standard reference materials (SRMs). It is a contribution that now has been mirrored around the world with reference materials being certified in at least 25 countries and routinely applied in more than twice that number. The result has been more accurate analyses of materials that impact our safety, health, and well-being. Received: 22 November 2000 Accepted: 22 November 2000     

Computational approaches in the design of synthetic receptors – A review

The rational design of molecularly imprinted polymers (MIPs) has been a major contributor to their reputation as “plastic antibodies” – high affinity robust synthetic receptors which can be optimally designed, and produced for a much reduced cost than their biological equivalents. Computational design has become a routine procedure in the production of MIPs, and has led to major advances in functional monomer screening, selection of cross-linker and solvent, optimisation of monomer(s)-template ratio and selectivity analysis. In this review the various computational methods will be discussed with reference to all the published relevant literature since the end of 2013, with each article described by the target molecule, the computational approach applied (whether molecular mechanics/molecular dynamics, semi-empirical quantum mechanics, ab initio quantum mechanics (Hartree-Fock, Møller–Plesset, etc.) or DFT) and the purpose for which they were used. Detailed analysis is given to novel techniques including analysis of polymer binding sites, the use of novel screening programs and simulations of MIP polymerisation reaction. The further advances in molecular modelling and computational design of synthetic receptors in particular will have serious impact on the future of nanotechnology and biotechnology, permitting the further translation of MIPs into the realms of analytics and medical technology.     

Fluorescence detection of pesticides using quantum dot materials – A review

High pesticide use, especially in agriculture, can lead to environmental pollution and potentially adverse health effects. As result, pesticide residues end up in different media, including water and food products, which may serve as direct routes for human exposure. There is thus a continuous drive to develop analytical methods for screening and quantification of these compounds in the different environmental media in which they may occur. Development of quantum dot (QD) based sensors for monitoring pesticides has gained momentum in recent years. QD materials have excellent and unique optical properties and have high fluorescence quantum yields compared to other fluorophores. They have thus been used in numerous studies for the development of probes for organic pollutants. In this paper we specifically review their application as fluorescence probes for pesticide detection in different media including water and in fruits and vegetables. The low detection limits reported demonstrate the potential use of these methods as alternatives to expensive and time-consuming conventional techniques. We also highlight potential limitations that these probes may present when it comes to routine application. Finally we discuss possible future improvements to enhance the selectivity and robustness of these sensors. We note that there is still a need for researchers to develop standardized QD based sensors which could lead to their commercialization and routine application.     

Advances in the determination of hindered amine light stabilizers – A review

Within this paper we discuss analytical strategies for the characterization and quantitation of hindered amine light stabilizers (HALS) an important sub-group of polymer additives. For the determination of monomeric HALS a range of mature and reliable techniques exists, allowing their determination in polymer extracts. If qualitative or semi-quantitative information suffices, certain techniques are capable of sampling directly from the polymer surface with limited or no sample preparation. Different strategies for the determination of complex oligomeric HALS in extracts from polymer samples are discussed. Here, approaches providing only a sum parameter including all HALS oligomers have been distinguished from more sophisticated technologies allowing the determination of single oligomers, their degradation and by-products. Particularly, the latter issue is facing increased interest as it provides important information for polymers aging studies. A tabulated overview provides comprehensive information on different analytical techniques suitable for HALS determination.     

Photocatalysis applied to organic synthesis – A green chemistry approach

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Gas chromatographic determination of perfluorocarboxylic acids in aqueous samples – A tutorial review

Determination of perfluorocarboxylic acids (PFCAs) by gas chromatography (GC) has been undertaken since 1980. However, only small number of studies can be found in the literature due to the major drawbacks associated with the GC determination of PFCAs such as high detection limits, a small range of analytes, long analysis time, and laborious derivatization prior to chromatographic separation. Liquid chromatography-tandem mass spectrometry (LC–MS²) can overcome these limitations of GC, and therefore has become the method of choice for the determination of PFCAs since 2001. Nevertheless, GC as a low-cost and commonly available analytical technique should not be ignored because of its inherent advantage over LC to identify PFCA isomers in environmental and biological matrices owing to its high-resolution power. In addition, GC provides an opportunity to crosscheck LC–MS² results that are often suspicious due to background contamination. This tutorial provides an overview of GC methods that have been used for the determination of PFCAs after derivatization. Moreover, performance characteristics of GC–MS are compared with that of LC–MS². PFCAs in aqueous samples were determined by both analytical techniques, and two sets of measurements were compared using the Bland-Altman plot. For both methods, reasons for false-positive and false-negative results (overestimation and underestimation of the PFCA concentration, respectively) are discussed, and accordingly some advice is offered on how to avoid erroneous results. Finally, major applications of GC and its future perspectives for the determination of PFCAs are discussed.     

Social acceptance of bioenergy in the context of climate change and sustainability – A review

Bioenergy development is gaining interest globally, and its social acceptance emerges as a determining factor for its implementation. This study is a short review of published articles discussing societal and public perceptions of bioenergy, including highlights of an interdisciplinary and three-dimensional approach (socioeconomic, local, and market). Social acceptance can be influenced by the awareness of climate change and its impacts, the knowledge of technologies and the perceived fairness of the preparatory and decision-making processes. The complex and multi-faceted supply chains of bioenergy projects call for careful consideration of sustainability.     

Synthesis and structural reactivity of inorganic–organic hybrid nanocomposites – A review

Chemistry of hybrid nanocomposites depends mainly on their reactivity and structural relationship. This review mainly reports on the processing techniques of inorganic–organic hybrid nanocomposites and their natural reactivity. Herein, the structure, processing methods and properties of nanocomposites with three different types of matrices are discussed in general. The perusal of this review enables the researchers to design a novel and simple route in processing the hybrid nanocomposites.     

Bioimaging mass spectrometry of trace elements – recent advance and applications of LA-ICP-MS: A review

Bioimaging using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) offers the capability to quantify trace elements and isotopes within tissue sections with a spatial resolution ranging about 10–100 μm. Distribution analysis adds to clarifying basic questions of biomedical research and enables bioaccumulation and bioavailability studies for ecological and toxicological risk assessment in humans, animals and plants. Major application fields of mass spectrometry imaging (MSI) and metallomics have been in brain and cancer research, animal model validation, drug development and plant science. Here we give an overview of latest achievements in methods and applications. Recent improvements in ablation systems, operation and cell design enabled progressively better spatial resolutions down to 1 μm. Meanwhile, a body of research has accumulated covering basic principles of the element architecture in animals and plants that could consistently be reproduced by several laboratories such as the distribution of Fe, Cu, Zn in rodent brain. Several studies investigated the distribution and delivery of metallo-drugs in animals. Hyper-accumulating plants and pollution indicator organisms have been the key topics in environmental science. Increasingly, larger series of samples are analyzed, may it be in the frame of comparisons between intervention and control groups, of time kinetics or of three-dimensional atlas approaches.     

Scopes of Bioanalytical Chromatography–Mass Spectrometry

Journal of Analytical Chemistry - The areas of application of modern bioanalytical chromatography–mass spectrometry are so extensive that any attempt to systematize them becomes subjective....     

Recent trends in the determination of biogenic amines in fermented beverages – A review

Biogenic amines (BA) are generally considered as a food hazard, even though there is not a threshold for these biomolecules in the European legislation, except for histamine in fishery products. These compounds are formed during the storage and processing of certain foods through microbiological activity, and when present in high concentrations, could have toxicological effects, causing health problems in consumers, especially to sensitive persons. This fact, in addition to the economical concern involved, makes it necessary to control the amounts of biogenic amines in foods. For all these reasons, literature on biogenic amines in different food products, especially in fermented beverages, is extensive. This review provides an overview of the most recent trends in the determination of biogenic amines in fermented beverages focusing on novelty, improvement and optimization of analytical methods. Hence, the different sample treatment procedures (including derivatization), the most important analytical techniques and the most frequent applications are described and discussed. Although biogenic amines have been determined in wine and other fermented beverages for decades, new advancements and technical possibilities have allowed to increase the accuracy and sensitivity of analytical methods, in order to overcome the challenges posed by the complex matrices and their high intrinsic variability. Thus, the different purposes of BA determination (food safety, production process or food microbiology research) and the most widely employed analytical techniques have been reviewed.     

Thermal degradation chemistry of poly(ethylene naphthalate) – A study by thermal volatilisation analysis

Although the fundamental degradation chemistry of poly(ethylene naphthalate), PEN, is thought to be similar to that of poly(ethylene terephthalate), PET, there is very little evidence in the literature to support this. This paper presents data on the thermal degradation of PEN, in comparison to PET, with particular reference to evolved gas analysis undertaken by thermal volatilisation analysis (TVA). Our thermal degradation studies highlight strong similarities in the degradation behaviour of PET and PEN, despite some evidence of increased thermal stability of PEN in comparison to PET. Identical primary and secondary thermal degradation mechanisms are proposed for PET and PEN, with radical degradation processes thought to dominate at high temperature.     

Recent advances in high resolution scanning electrochemical microscopy of living cells – A review

This review discusses advances in the field of high resolution scanning electrochemical microscopy (HR-SECM) and scanning ion conductance microscopy (SICM) to study living cells. Relevant references from the advent of this technique in the late 1980s to most recent contributions in 2012 are presented with special discussion on high resolution images. A clear progress especially within the last 5 years can be seen in the field of HR-SECM. Furthermore, we also concentrate on the intrinsic properties of SECM imaging techniques e.g. different modes of image acquisition, their advantages and disadvantages in imaging living cells and strategies for further enhancement of image resolution, etc. Some of the recent advances of SECM in nanoimaging have also been discussed which may have potential applications in high resolution imaging of cellular processes.