Check out our New Publishers' Select for Free Articles

Analytical and Bioanalytical Chemistry (v.399, #1)

Nanomaterials for improved analytical processes by M. Valcárcel; B. M. Simonet (pp. 1-2).

has been full Professor of Analytical Chemistry at the University of Córdoba (Spain) since 1976. He is the author and co-author of 800 scientific articles (in indexed journals), seven scientific monographs, eight textbooks and 16 book chapters. He has been the coordinator of 25 Spanish and 14 international research projects, as well as having 12 contracts with private firms and acting as a promoter of a spin-off devoted to nanotechnology. He has been a co-supervisor of 70 doctoral theses and an invited lecturer at more than 70 international meetings. He is the recipient of several scientific national (e.g. Award in Chemistry in Spain, 2005) and international (e.g. Robert Boyle Medal of the Royal Society of Chemistry, UK, 2004) prizes and is a member of the Spanish Royal Academy of Sciences. is a senior researcher at the University of Córdoba. He is the author and co-author of 80 scientific articles, two textbooks and five book chapters. He has been a co-supervisor of four doctoral theses and presently he is supervising seven doctoral theses. He has participated in five scientific research projects and is the scientific director of a spin-off devoted to nanotechnology. He has presented 21 oral communications at international meetings

Nanoparticles as contrast agents for in-vivo bioimaging: current status and future perspectives by Megan A. Hahn; Amit K. Singh; Parvesh Sharma; Scott C. Brown; Brij M. Moudgil (pp. 3-27).

Nanoparticle-based contrast agents are quickly becoming valuable and potentially transformative tools for enhancing medical diagnostics for a wide range of in-vivo imaging modalities. Compared with conventional molecular-scale contrast agents, nanoparticles (NPs) promise improved abilities for in-vivo detection and potentially enhanced targeting efficiencies through longer engineered circulation times, designed clearance pathways, and multimeric binding capacities. However, NP contrast agents are not without issues. Difficulties in minimizing batch-to-batch variations and problems with identifying and characterizing key physicochemical properties that define the in-vivo fate and transport of NPs are significant barriers to the introduction of new NP materials as clinical contrast agents. This manuscript reviews the development and application of nanoparticles and their future potential to advance current and emerging clinical bioimaging techniques. A focus is placed on the application of solid, phase-separated materials, for example metals and metal oxides, and their specific application as contrast agents for in-vivo near-infrared fluorescence (NIRF) imaging, magnetic resonance imaging (MRI), positron emission tomography (PET), computed tomography (CT), ultrasound (US), and photoacoustic imaging (PAI). Clinical and preclinical applications of NPs are identified for a broad spectrum of imaging applications, with commentaries on the future promise of these materials. Emerging technologies, for example multifunctional and theranostic NPs, and their potential for clinical advances are also discussed.

Keywords: Nanoparticles; In-vivo imaging; Clinical; Characterization; Multifunctional; Theranostic

Nanoparticles as fluorescent labels for optical imaging and sensing in genomics and proteomics by Ana María Coto-García; Emma Sotelo-González; María Teresa Fernández-Argüelles; Rosario Pereiro; José M. Costa-Fernández; Alfredo Sanz-Medel (pp. 29-42).

Optical labelling reagents (dyes and fluorophores) are an essential component of probe-based biomolecule detection, an approach widely employed in a variety of areas including environmental analysis, disease diagnostics, pharmaceutical screening, and proteomic and genomic studies. Recently, functional nanomaterials, as a new generation of high-value optical labels, have been applied to molecular detection. The great potential of such recent optical labels has paved the way for the development of new biomolecule assays with unprecedented analytical performance characteristics, related to sensitivity, multiplexing capability, sample throughput, cost-effectiveness and ease of use. This review aims to provide an overview of recent advances using different nanoparticles (such as quantum dots, rare earth doped nanoparticles or gold nanoparticles) for analytical genomics and proteomics, with particular emphasis on the outlook for different strategies of using nanoparticles for bioimaging and quantitative bioanalytical applications, as well as possibilities and limitations of nanoparticles in such a growing field. Figure Nanoparticles for analytical genomics and proteomics, with particular emphasis on bioimaging and quantitative bioanalytical applications of nanoparticles

Keywords: Proteomics; Nanoparticle; Bioanalysis; Genomics; Imaging

Analytical potential of hybrid nanoparticles by A. I. López-Lorente; B. M. Simonet; M. Valcárcel (pp. 43-54).

The growing use of nanoparticles in the analytical process in recent years has set a new trend towards the simplification of analytical methods and improvement of their performance. Miniaturization and nanotechnology have allowed new analytical challenges to be met. Hybrid nanoparticles in particular possess exceptional properties enabling further improvement of analytical methods. Despite the continuous developments in their synthesis and characterization, hybrid nanomaterials have scarcely been used in analytical chemistry, however. This paper discusses the analytical potential of hybrid nanoparticles in terms of their special characteristics and properties, and describes their analytical applications.

Keywords: Nanoparticles; Nanotechnology; Hybrid nanoparticle; Analytical tools

Nanoscopic optical sensors based on functional supramolecular hybrid materials by Ramón Martínez-Máñez; Félix Sancenón; Mandy Hecht; Mustafa Biyikal; Knut Rurack (pp. 55-74).

This review highlights how the combination of supramolecular principles and nanoscopic solid structures enables the design of new hybrid sensing ensembles with improved sensitivity and/or selectivity and for the targeting of analytes for which selectivity is hard to achieve by conventional methods. Such ideas are bridging the gap between molecules, materials sciences and nanotechnology. Relevant examples will be detailed, taking into account functional aspects such as (1) enhanced coordination of functionalized solids, (2) enhanced signalling through preorganization, (3) signalling by assembly–disassembly of nanoscopic objects, (4) biomimetic probes utilizing discrimination by polarity and size and (5) distinct switching and gating protocols. These strategies are opening new prospects for sensor research and signalling paradigms at the frontier between nanotechnology, smart materials and supramolecular chemistry.

Keywords: Supramolecular chemistry; Optical probes; Nanotechnology; Hybrid organic–inorganic materials

Micropreconcentration units based on carbon nanotubes (CNT) by Chaudhery Mustansar Hussain; Somenath Mitra (pp. 75-89).

Carbon nanotubes (CNT) have some highly desirable sorbent characteristics which make them attractive for a variety of analytical applications. High adsorption capacity and rapid desorbability make CNT excellent candidates for micro-scale devices for gas and liquid-phase analysis. In gas-phase analysis one can implement a micro-concentrator or a micro-sorbent trap, which have been used in a variety of on-line chromatography and sensing applications. Interesting liquid-phase microtrapping applications include micro-scale solid-phase extraction (μ-SPE) and solid-phase micro extraction (SPME). In addition, the ease of surface functionalization, self assembly by chemical vapor deposition, and the formation of diverse polymer composites may well make CNT the high-performance sorbent of the future.

Keywords: Carbon nanotubes; Micro-concentrator; Microtrap; Micro-scale solid-phase extraction (μ-SPE); Solid-phase micro extraction (SPME)

Recent developments and applications of hybrid surface plasmon resonance interfaces in optical sensing by Shuyan Gao; Naoto Koshizaki (pp. 91-101).

Nanostructured noble metals exhibit an intense optical near field due to surface plasmon resonance, therefore promising widespread applications and being of interest to a broad spectrum of scientists, ranging from physicists, chemists, and materials scientists to biologists. A wealth of research is available discussing the synthesis, characterization, and application of noble metal nanoparticles in optical sensing. However, with respect to the sensitivity of the frequency and width of these surface plasmon resonance modes to the particle’s shape, size, and environment, in nearly every case, success strongly depends on the availability of highly stable, adhesive, and sensitive nanoparticles. This undoubtedly presents a challenging task to nanofabrication. The past decade has witnessed fascinating advances in this field, in particular, the construction of oxide-based hybrid plasmonic interfaces to overcome the problem addressed above by (1) coating the metallic nanostructures with thin overlayers to form sandwiched structures or (2) embedding metallic nanostructures in a dielectric matrix to obtain metal/dielectric matrix nanocomposite films. In this critical review, we focus on recent work related to this field, beginning with a presentation of hybrid films with enhanced structural and optical stability, readily and selectively designed using chemical and physical techniques. We then illustrate their interesting optical properties and demonstrate exciting evidence for the postulated application in surface plasmon sensing fields. Finally, we survey the work remaining to be done for that potential to be realized. Figure This critical review concentrates on advances involving the synthesis, characterization, and practical application of oxide-based hybrid surface plasmon resonance interfaces with aiming at providing a suitable alternative to facilitate the application of surface plasmon resonance optical sensors, along with significant advances made over the last several years

Keywords: Hybrid plasmonic interfaces; Noble metal; Oxide matrix; Stability; Sensitivity; Surface plasmon resonance sensing

Potential role of gold nanoparticles for improved analytical methods: an introduction to characterizations and applications by Chung-Shu Wu; Fu-Ken Liu; Fu-Hsiang Ko (pp. 103-118).

Nanoparticle-based material is a revolutionary scientific and engineering venture that will invariably impact the existing analytical separation and preconcentration for a variety of analytes. Nanoparticles can be regarded as a hybrid between small molecule and bulk material. A material on the nanoscale produces considerable changes on various properties, making them size- and shape-dependent. Gold nanoparticles (Au NPs), one of the wide variety of core materials available, coupled with tunable surface properties in the form of inorganic or inorganic-organic hybrid have been reported as an excellent platform for a broad range of analytical methods. This review aims to introduce the basic principles, examples, and descriptions of methods for the characterization of Au NPs by using chromatography, electrophoresis, and self-assembly strategies for separation science. Some of the latest important applications of using Au NPs as stationary phases toward open-tubular capillary electrochromatography, gas chromatography, and liquid chromatography as well as roles of run buffer additive to enhance separation and preconcentration in the field of chromatographic, electrophoretic and in chip-based systems are reviewed. Additionally, we review Au NPs-assisted state-of-the-art techniques involving the use of micellar electrokinetic chromatography, an online diode array detector, solid-phase extraction, and mass spectrometry for the preconcentration of some chemical compounds and biomolecules. Figure Potential role of gold nanoparticles by using chromatography, electrophoresis and self-assembly strategies for the improvement of analytical processes.

Keywords: Gold nanoparticles; Separation; Preconcentration; Chromatography; Electrophoresis; Self-assembly

Rapid detection of Aspergillus flavus in rice using biofunctionalized carbon nanotube field effect transistors by Raquel A. Villamizar; Alicia Maroto; F. Xavier Rius (pp. 119-126).

In the present study, we have used carbon nanotube field effect transistors (FET) that have been functionalized with protein G and IgG to detect Aspergillus flavus in contaminated milled rice. The adsorbed protein G on the carbon nanotubes walls enables the IgG anti-Aspergillus antibodies to be well oriented and therefore to display full antigen binding capacity for fungal antigens. A solution of Tween 20 and gelatine was used as an effective blocking agent to prevent the non-specific binding of the antibodies and other moulds and also to protect the transducer against the interferences present in the rice samples. Our FET devices were able to detect at least 10 μg/g of A. flavus in only 30 min. To evaluate the selectivity of our biosensors, Fusarium oxysporum and Penicillium chrysogenum were tested as potential competing moulds for A. flavus. We have proved that our devices are highly selective tools for detecting mycotoxigenic moulds at low concentrations in real samples.

Keywords: Biosensor; Field effect transistors; Carbon nanotubes; Moulds; Aspergillus flavus

Graphene-based electrochemical sensor for detection of 2,4,6-trinitrotoluene (TNT) in seawater: the comparison of single-, few-, and multilayer graphene nanoribbons and graphite microparticles by Madeline Shuhua Goh; Martin Pumera (pp. 127-131).

The detection of explosives in seawater is of great interest. We compared response single-, few-, and multilayer graphene nanoribbons and graphite microparticle-based electrodes toward the electrochemical reduction of 2,4,6-trinitrotoluene (TNT). We optimized parameters such as accumulation time, accumulation potential, and pH. We found that few-layer graphene exhibits about 20% enhanced signal for TNT after accumulation when compared to multilayer graphene nanoribbons. However, graphite microparticle-modified electrode provides higher sensitivity, and there was no significant difference in the performance of single-, few-, and multilayer graphene nanoribbons and graphite microparticles for the electrochemical detection of TNT. We established the limit of detection of TNT in untreated seawater at 1 μg/mL. Figure Graphene for detection of TNT based explosives

Keywords: Electrochemistry; Sensors; Explosives

Toward a solid-phase nucleic acid hybridization assay within microfluidic channels using immobilized quantum dots as donors in fluorescence resonance energy transfer by Lu Chen; W. Russ Algar; Anthony J. Tavares; Ulrich J. Krull (pp. 133-141).

The optical properties and surface area of quantum dots (QDs) have made them an attractive platform for the development of nucleic acid biosensors based on fluorescence resonance energy transfer (FRET). Solid-phase assays based on FRET using mixtures of immobilized QD–oligonucleotide conjugates (QD biosensors) have been developed. The typical challenges associated with solid-phase detection strategies include non-specific adsorption, slow kinetics of hybridization, and sample manipulation. The new work herein has considered the immobilization of QD biosensors onto the surfaces of microfluidic channels in order to address these challenges. Microfluidic flow can be used to dynamically control stringency by adjustment of the potential in an electrokinetic-based microfluidics environment. The shearing force, Joule heating, and the competition between electroosmotic and electrophoretic mobilities allow the optimization of hybridization conditions, convective delivery of target to the channel surface to speed hybridization, amelioration of adsorption, and regeneration of the sensing surface. Microfluidic flow can also be used to deliver (for immobilization) and remove QD biosensors. QDs that were conjugated with two different oligonucleotide sequences were used to demonstrate feasibility. One oligonucleotide sequence on the QD was available as a linker for immobilization via hybridization with complementary oligonucleotides located on a glass surface within a microfluidic channel. A second oligonucleotide sequence on the QD served as a probe to transduce hybridization with target nucleic acid in a sample solution. A Cy3 label on the target was excited by FRET using green-emitting CdSe/ZnS QD donors and provided an analytical signal to explore this detection strategy. The immobilized QDs could be removed under denaturing conditions by disrupting the duplex that was used as the surface linker and thus allowed a new layer of QD biosensors to be re-coated within the channel for re-use of the microfluidic chip. Figure Schematic view of detection of nucleic acid hybridization within microfluidic channels using immobilized quantum dots as donors in fluorescence resonance energy transfer

Keywords: Oligonucleotide; Hybridization; Fluorescence resonance energy transfer (FRET); Microfluidics; Biosensor; Quantum dots

Single-walled carbon nanotubes for improved enantioseparations on a chiral ionic liquid stationary phase in GC by Li Zhao; Ping Ai; Ai-Hong Duan; Li-Ming Yuan (pp. 143-147).

In order to investigate whether the use of single-walled carbon nanotubes can improve enantioseparations on an ionic liquid stationary phase, a chiral ionic liquid, (R)-N,N,N-trimethyl-2-aminobutanol-bis(trifluoromethanesulfon)imidate, was synthesized. Two capillary columns, one containing the chiral ionic liquid and the other containing the single-walled carbon nanotubes and the chiral ionic liquid, were then prepared for GC. The results of the separations achieved with these columns show that coating the chiral ionic liquid stationary phase onto the capillary column containing single-walled carbon nanotubes improves the enantioselectivety of the chiral ionic liquid. This work indicates that using single-walled carbon nanotubes in this manner enables the application range of such GC chiral separations to be extended. Figure Chromatograms of (±)-phenylethanol racemates on a chiral ionic liquid column (a) and a column containing SWNTs and the chiral ionic liquid (b)

Keywords: Single-walled carbon nanotubes; Chiral ionic liquid; Stationary phase; GC

Analytical Chemistry 2.0—an open-access digital textbook by David Harvey (pp. 149-152).

is Professor of Chemistry and Biochemistry and Vice President for Academic Affairs at DePauw University. He maintains an active research program in developing new curricular materials for analytical chemistry classes and laboratories, and in studying the interactions of metals at the sediment–solution interface, especially the analysis of metals incorporated in sediments and soils. He is active in the Analytical Sciences Digital Library, currently serving as the ASDL Community Editor.

The sporting nature of science by Geraldine Richmond (pp. 153-155).

is the Richard M. and Patricia H. Noyes Professor in Chemistry at the University of Oregon. Her research team uses nonlinear optical spectroscopy and computational methods to understand the chemistry and physics that occurs at complex surfaces and interfaces that have relevance to important problems in energy production, environmental remediation, atmospheric chemistry and biomolecular surfaces ( http://richmondscience.uoregon.edu ). She is equally active in issues of science literacy and the recruitment and retention of underrepresented groups in science and engineering. In 1998, she started COACh and currently serves as its Director.

The green beans challenge by Hervé This (pp. 157-158).

Solution to the uncooked egg challenge by Hervé This (pp. 159-159).

K. Balasubramaniam and M. Burghard (Eds.): Carbon nanotubes. Methods and protocols by Frank Schleifenbaum (pp. 161-162).

Chih-Ming Ho (Ed.): Micro/nano technology systems for biomedical applications. Microfluidics, optics and surface chemistry by Takehiko Kitamori (pp. 163-164).

Allan Jamieson, Andre Moenssens (Eds.): Wiley encyclopedia of forensic science by John V. Goodpaster (pp. 165-166).

Dennis Meredith: Explaining research. How to reach key audiences to advance your work by Sara Shinton (pp. 167-168).

A fascinating insight of the analytical potentialities of infrared and raman spectroscopic imaging by Olivier Piot (pp. 169-170).

Nanostructured materials in potentiometry by Ali Düzgün; Gustavo A. Zelada-Guillén; Gastón A. Crespo; Santiago Macho; Jordi Riu; F. Xavier Rius (pp. 171-181).

Potentiometry is a very simple electrochemical technique with extraordinary analytical capabilities. It is also well known that nanostructured materials display properties which they do not show in the bulk phase. The combination of the two fields of potentiometry and nanomaterials is therefore a promising area of research and development. In this report, we explain the fundamentals of potentiometric devices that incorporate nanostructured materials and we highlight the advantages and drawbacks of combining nanomaterials and potentiometry. The paper provides an overview of the role of nanostructured materials in the two commonest potentiometric sensors: field-effect transistors and ion-selective electrodes. Additionally, we provide a few recent examples of new potentiometric sensors that are based on receptors immobilized directly onto the nanostructured material surface. Moreover, we summarize the use of potentiometry to analyze processes involving nanostructured materials and the prospects that the use of nanopores offer to potentiometry. Finally, we discuss several difficulties that currently hinder developments in the field and some future trends that will extend potentiometry into new analytical areas such as biology and medicine.

Keywords: Potentiometry; Nanostructured materials; Sensors; Field-effect transistors; Ion-selective electrodes; Nanoparticles; Nanotubes; Nanowires; Graphene

Trends in computational simulations of electrochemical processes under hydrodynamic flow in microchannels by Michael F. Santillo; Andrew G. Ewing; Michael L. Heien (pp. 183-190).

Computational modeling and theoretical simulations have recently become important tools for the development, characterization, and validation of microfluidic devices. The recent proliferation of commercial user-friendly software has allowed researchers in the microfluidics community, who might not be familiar with computer programming or fluid mechanics, to acquire important information on microsystems used for sensors, velocimetry, detection for microchannel separations, and microfluidic fuel cells. We discuss the most popular computational technique for modeling these systems—the finite element method—and how it can be applied to model electrochemical processes coupled with hydrodynamic flow in microchannels. Furthermore, some of the limitations and challenges of these computational models are also discussed. Figure

Keywords: Bioanalytical methods; Chemical sensors; Electroanalytical methods; Modeling; Microfluidics/microfabrication

Trends in the bioanalytical applications of microfluidic electrocapture by Mohammadreza Shariatgorji; Juan Astorga-Wells; Leopold L. Ilag (pp. 191-195).

Downscaled analytical tools for sample preparation have offered benefits such as higher throughput, easier automation and lower sample/reagent consumption. Microfluidic electrocapture, which is a newly developed sample preparation/manipulation system, uses an electric field to trap and separate charged species without using any solid sorbent. The feasibility of using microfluidic electrocapture is reported for separation, clean-up, concentration, microreactions and complexation studies of proteins, peptides and other biologically important biomolecules. The instrumentation and applications of microfluidic electrocapture are reviewed and an overview is provided of future perspectives offered by the current and envisaged platforms.

Keywords: Sample preparation; Mass spectrometry; Microfluidic; Electrocapture

Flow field-flow fractionation with multiangle light scattering detection for the analysis and characterization of functional nanoparticles by Pierluigi Reschiglian; Diana C. Rambaldi; Andrea Zattoni (pp. 197-203).

Chemical modifications of nanoparticles (NPs) are often necessary to improve their features as spectroscopic tracers or chemical sensors, or to increase water solubility and biocompatibility of NPs for applications in nano-biotechnology. The description of newly designed functional NPs is rapidly expanding. However, the full exploitation of technologies based on functional NPs requires accurate, precise, and rugged methods for their analysis and characterization. When quality control protocols for industrial NP production are required, these methods must be applied on a routine basis. Since many properties of functional NPs are size-dependent, particle size distribution analysis provides fundamental information. The actual presence and distribution of functional groups in the NPs as well as their chemical features in the nanodispersed state are also fundamental aspects to be additionally analyzed. However, all these tasks cannot be afforded by a single method. Separation methods are necessary to isolate the newly synthesized NPs from the reagents in solution, and then coupled methods can characterize the isolated NPs. Flow field-flow fractionation (F4) is increasingly used as a mature separation method to size-sort and isolate NPs for their further analysis or size characterization by multiangle light scattering (MALS) detection. In this work, firstly the application of F4-MALS to different types of functional NPs is concisely overviewed. We then illustrate our recent applications of F4-MALS coupled with spectroscopic methods for the analysis and characterization of functional NPs. We finally provide an outlook of what we believe are the trends to make F4 soon become the required method in routine-based analytical platforms for quality control protocols of industrial-scale, functional NP production.

Keywords: Nanotechnology; Functional nanoparticles; Flow field-flow fractionation; Multiangle light scattering

Optical ring resonators for biochemical and chemical sensing by Yuze Sun; Xudong Fan (pp. 205-211).

In the past few years optical ring resonators have emerged as a new sensing technology for highly sensitive detection of analytes in liquid or gas. This article introduces the ring resonator sensing principle, describes various ring resonator sensor designs, reviews the current state of the field, and presents an outlook of possible applications and related research and development directions. Figure Various types of optical ring resonators for biochemical and chemical sensing

Keywords: Optical ring resonators; Biological sensors; Chemical sensors; Vapor sensors

Inductively coupled plasma mass spectrometry: recent trends and developments by Carsten Engelhard (pp. 213-219).

This year inductively coupled plasma mass spectrometry (ICP-MS) moves into the fourth decade of development. In this article, some recent trends and developments in ICP-MS are reviewed, with special focus on instrumental development and emerging applications. Some key trends include a novel mass spectrometer for elemental and speciation analysis in Mattauch–Herzog geometry with a focal-plane-camera array detector. The reason for this development is the possibility to record the full elemental mass range simultaneously and all the time. Monitoring fast transient signals in chromatography or laser ablation is now possible and will become an important asset in future studies, e.g., for isotope ratio analysis. In addition, there is a lot of new activity and interest in the area of nanosciences and medicine. Here, instrumental developments are reported that allow the direct analysis of microparticles and single cells. Figure ICP-MS: Recent trends and developments are reviewed with special focus on instrumentation

Keywords: Inductively coupled plasma mass spectrometry; Trends; Ultratrace analysis; Simultaneous detection; Array detector; Time of flight; Nanoparticles; Single-cell analysis; Laser ablation

Analysis of polyfluorinated compounds in foods by Sheryl A. Tittlemier; Eric Braekevelt (pp. 221-227).

Polyfluorinated compounds (PFCs) are a relatively new and diverse set of compounds analyzed as contaminants in food. Their unique physical-chemical properties dictate the methods used for their analysis. Current analyses of the more volatile PFCs involve gas chromatography–mass spectrometry; liquid chromatography–tandem mass spectrometry is generally used for the less volatile PFCs. Considerations in the analysis of PFCs in foods include contamination from the widespread presence of materials that contain various PFCs, endogenous interfering compounds, and matrix effects. Future opportunities for research on PFCs in food exist, particularly in the areas of biological molecule–PFC interactions and the effects of food processing on these interactions. Future research will be facilitated by the synthesis of a wider variety of analytical standards.

Keywords: Polyfluorinated compounds; Food; Analytical methods; PFOS; PFOA

Recent advances in micro-scale and nano-scale high-performance liquid-phase chromatography for proteome research by Dingyin Tao; Lihua Zhang; Yichu Shan; Zhen Liang; Yukui Zhang (pp. 229-241).

High-performance liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC–ESI-MS–MS) is regarded as one of the most powerful techniques for separation and identification of proteins. Recently, much effort has been made to improve the separation capacity, detection sensitivity, and analysis throughput of micro- and nano-HPLC, by increasing column length, reducing column internal diameter, and using integrated techniques. Development of HPLC columns has also been rapid, as a result of the use of submicrometer packing materials and monolithic columns. All these innovations result in clearly improved performance of micro- and nano-HPLC for proteome research.

Keywords: Proteome; Micro-HPLC; Nano-HPLC; Multi-dimensional separation; MS–MS

Recent advances of chromatography and mass spectrometry in lipidomics by Min Li; Zhigui Zhou; Honggang Nie; Yu Bai; Huwei Liu (pp. 243-249).

Lipidomics, as a novel branch of metabolomics, which is aimed at comprehensive analysis of lipids and their biological roles with respect to health and diseases, has attracted increased attention from biological and analytical scientists. As a result of the complexity and diversity of lipids, accurate identification and efficient separation are required for lipidomics analysis. Mass spectrometry (MS) and chromatography have been extensively developed in the past few decades and hold a distinguished position in qualification and separation science. They are powerful and indispensable tools for lipidomics. Herein, we present the recent advancement of MS, chromatography, and their hyphenation technologies in lipidomics.

Keywords: Lipidomics; MS; Liquid chromatography; Gas chromatography; Thin-layer chromatography; Capillary electrophoresis

Pharmaceutical residues in environmental waters and wastewater: current state of knowledge and future research by Despo Fatta-Kassinos; Sureyya Meric; Anastasia Nikolaou (pp. 251-275).

Pollution from pharmaceuticals in the aquatic environment is now recognized as an environmental concern in many countries. This has led to the creation of an extensive area of research, including among others: their chemical identification and quantification; elucidation of transformation pathways when present in wastewater-treatment plants or in environmental matrices; assessment of their potential biological effects; and development and application of advanced treatment processes for their removal and/or mineralization. Pharmaceuticals are a unique category of pollutants, because of their special characteristics, and their behavior and fate cannot be simulated with other chemical organic contaminants. Over the last decade the scientific community has embraced research in this specific field and the outcome has been immense. This was facilitated by advances in chromatographic techniques and relevant biological assays. Despite this, a number of unanswered questions exist and still there is much room for development and work towards a more solid understanding of the actual consequences of the release of pharmaceuticals in the environment. This review tries to present part of the knowledge that is currently available with regard to the occurrence of pharmaceutical residues in aquatic matrices, the progress made during the last several years on identification of such compounds down to trace levels, and of new, previously unidentified, pharmaceuticals such as illicit drugs, metabolites, and photo-products. It also tries to discuss the main recent findings in respect of the capacity of various treatment technologies to remove these contaminants and to highlight some of the adverse effects that may be related to their ubiquitous existence. Finally, socioeconomic measures that may be able to hinder the introduction of such compounds into the environment are briefly discussed.

Keywords: Pharmaceuticals; Water/wastewater; Analysis; Removal technologies; Transformation by-products; Adverse effects

Solventless sample preparation techniques based on solid- and vapour-phase extraction by Magdalena Urbanowicz; Bożena Zabiegała; Jacek Namieśnik (pp. 277-300).

The main objective of this review is to critically evaluate recent developments in solventless sample preparation techniques. The potential of a variety of sample preparation techniques based on solid- and vapour-phase extraction techniques is evaluated. Direct thermal extraction and derivatization processes to facilitate the extraction of analytes in different areas are included. The applicability, disadvantages and advantages of each sample preparation technique for the determination of environmental contaminants in different matrices are discussed.

Keywords: Sample preparation; Thermal desorption; Gas chromatography; Extraction techniques; Environmental contaminants

DC insulator dielectrophoretic applications in microdevice technology: a review by Soumya K. Srivastava; Aytug Gencoglu; Adrienne R. Minerick (pp. 301-321).

Dielectrophoresis is a noninvasive, nondestructive, inexpensive, and fast technique for the manipulation of bioparticles. Recent advances in the field of dielectrophoresis (DEP) have resulted in new approaches for characterizing the behavior of particles and cells using direct current (DC) electric fields. In such approaches, spatial nonuniformities are created in the channel by embedding insulating obstacles in the channel or flow field in order to perform separation or trapping. This emerging field of dielectrophoresis is commonly termed DC insulator dielectrophoresis (DC-iDEP), insulator-based dielectrophoresis (iDEP), or electrodeless dielectrophoresis (eDEP). In many microdevices, this form of dielectrophoresis has advantages over traditional AC-DEP, including single material microfabrication, remotely positioned electrodes, and reduced fouling of the test region. DC-iDEP applications have included disease detection, separation of cancerous cells from normal cells, and separation of live from dead bacteria. However, there is a need for a critical report to integrate these important research findings. The aim of this review is to provide an overview of the current state-of-art technology in the field of DC-iDEP for the separation and trapping of inert particles and cells. In this article, a review of the concepts and theory leading to the manipulation of particles via DC-iDEP is given, and insulating obstacle geometry designs and the characterization of device performance are discussed. This review compiles and compares the significant findings obtained by researchers in handling and manipulating particles. Figure Common insulating obstacle geometries reported in the literature. Red zones indicate where the particles experience the maximum dielectrophoretic effect under DC or DC plus AC-biased electric field conditions

Keywords: DC dielectrophoresis; Insulator-based dielectrophoresis; Electrodeless dielectrophoresis; Microfluidics; Electrokinetic separations; Bioparticles

High-resolution continuum source graphite furnace atomic absorption spectrometry: Is it as good as it sounds? A critical review by Martín Resano; Esperanza García-Ruiz (pp. 323-330).

The recent arrival of high-resolution continuum source atomic absorption spectrometry represents a potential revolution in this field, in particular for direct analysis of complex samples. This review tries to illustrate the main advantages of this technology, paying particular attention to the development of direct solid sampling methods. Three solid sampling applications will be discussed, each one of them highlighting one of the main advantages of this technique. The review also intends to clarify some misconceptions on the true potential of the instrumentation that is currently commercially available, such as its performance for multielemental analysis. Figure Graphite furnace: still burning hot!

Keywords: High-resolution continuum source atomic absorption spectrometry; Graphite furnace; Solid sampling analysis

Clay pigment structure characterisation as a guide for provenance determination—a comparison between laboratory powder micro-XRD and synchrotron radiation XRD by Silvie Švarcová; Petr Bezdička; David Hradil; Janka Hradilová; Ivo Žižak (pp. 331-336).

Application of X-ray diffraction (XRD)-based techniques in the analysis of painted artworks is not only beneficial for indisputable identification of crystal constituents in colour layers, but it can also bring insight in material crystal structure, which can be affected by their geological formation, manufacturing procedure or secondary changes. This knowledge might be helpful for art historic evaluation of an artwork as well as for its conservation. By way of example of kaolinite, we show that classification of its crystal structure order based on XRD data is useful for estimation of its provenance. We found kaolinite in the preparation layer of a Gothic wall painting in a Czech church situated near Karlovy Vary, where there are important kaolin deposits. Comparing reference kaolin materials from eight various Czech deposits, we found that these can be differentiated just according to the kaolinite crystallinity. Within this study, we compared laboratory powder X-ray micro-diffraction (micro-XRD) with synchrotron radiation X-ray diffraction analysing the same real sample. We found that both techniques led to the same results. Figure XRD patterns of kaolins from Czech deposits compared with a XRD pattern from a wall painting found in St. Maria-Magdalena Church in Bor.

Keywords: Powder X-ray micro-diffraction; Synchrotron radiation; Kaolinite; Wall painting; Pigment provenance

A digital microfluidic approach to heterogeneous immunoassays by Elizabeth M. Miller; Alphonsus H. C. Ng; Uvaraj Uddayasankar; Aaron R. Wheeler (pp. 337-345).

A digital microfluidic (DMF) device was applied to a heterogeneous sandwich immunoassay. The digital approach to microfluidics manipulates samples and reagents in the form of discrete droplets, as opposed to the streams of fluid used in microchannels. Since droplets are manipulated on relatively generic 2-D arrays of electrodes, DMF devices are straightforward to use, and are reconfigurable for any desired combination of droplet operations. This flexibility makes them suitable for a wide range of applications, especially those requiring long, multistep protocols such as immunoassays. Here, we developed an immunoassay on a DMF device using Human IgG as a model analyte. To capture the analyte, an anti-IgG antibody was physisorbed on the hydrophobic surface of a DMF device, and DMF actuation was used for all washing and incubation steps. The bound analyte was detected using FITC-labeled anti-IgG, and fluorescence after the final wash was measured in a fluorescence plate reader. A non-ionic polymer surfactant, Pluronic F-127, was added to sample and detection antibody solutions to control non-specific binding and aid in movement via DMF. Sample and reagent volumes were reduced by nearly three orders of magnitude relative to conventional multiwell plate methods. Since droplets are in constant motion, the antibody–antigen binding kinetics is not limited by diffusion, and total analysis times were reduced to less than 2.5 h per assay. A multiplexed device comprising several DMF platforms wired in series further increased the throughput of the technique. A dynamic range of approximately one order of magnitude was achieved, with reproducibility similar to the assay when performed in a 96-well plate. In bovine serum samples spiked with human IgG, the target molecule was successfully detected in the presence of a 100-fold excess of bovine IgG. It was concluded that the digital microfluidic format is capable of carrying out qualitative and quantitative sandwich immunoassays with a dramatic reduction in reagent usage and analysis time compared to macroscale methods.

Keywords: Digital microfluidics; Immunoassay; Electrowetting

Droplet microfluidics with magnetic beads: a new tool to investigate drug–protein interactions by Dario Lombardi; Petra S. Dittrich (pp. 347-352).

In this study, we give the proof of concept for a method to determine binding constants of compounds in solution. By implementing a technique based on magnetic beads with a microfluidic device for segmented flow generation, we demonstrate, for individual droplets, fast, robust and complete separation of the magnetic beads. The beads are used as a carrier for one binding partner and hence, any bound molecule is separated likewise, while the segmentation into small microdroplets ensures fast mixing, and opens future prospects for droplet-wise analysis of drug candidate libraries. We employ the method for characterization of drug–protein binding, here warfarin to human serum albumin. The approach lays the basis for a microfluidic droplet-based screening device aimed at investigating the interactions of drugs with specific targets including enzymes and cells. Furthermore, the continuous method could be employed for various applications, such as binding assays, kinetic studies, and single cell analysis, in which rapid removal of a reactive component is required.

Keywords: Microfluidics; Digital microfluidics; Droplet splitting; Magnetic beads; Serum albumin; Warfarin; Equilibrium constants; Drug–protein interactions

Slowed diffusion of single nanoparticles in the extracellular microenvironment of living cells revealed by darkfield microscopy by Rui Zhou; Bin Xiong; Yan He; Edward S. Yeung (pp. 353-359).

We obtained vertical distribution of diffusion coefficients of single gold nanoparticles (AuNPs) in the extracellular solution space of living cells with optical sectioning darkfield microscopy. It was identified that before reaching the plasma membrane surface during their cellular uptake process, AuNPs must diffuse through a viscous pericellular “buffer zone” several microns thick where their motion is retarded significantly. The pericellular layer exists in two different cell types and is unrelated to the surface chemistry of AuNPs. Further studies on its properties and manipulation may help the development of nanoparticle probes and carriers.

Keywords: Nanoparticles; Extracellular; Single particle tracking; Optical sectioning imaging

Electrochemical properties and temperature dependence of a recombinant laccase from Thermus thermophilus by Xin Liu; Megan Gillespie; Ayca Demirel Ozel; Emre Dikici; Sylvia Daunert; Leonidas G. Bachas (pp. 361-366).

The electrochemical properties of a laccase from Thermus thermophilus HB27 (Tth-laccase) were characterized. The gene encoding the laccase was cloned and overexpressed in Escherichia coli. One-step purification of the corresponding apo-enzyme was achieved by nickel-affinity chromatography. Copper was incorporated into the apo-laccase as the cofactor to yield the holo-enzyme. The temperature-dependent catalytic activity of the laccase was investigated by spectrophotometric as well as electrochemical methods. Specifically, the catalytic properties of the enzyme were characterized by employing a photometric assay based on the oxidation of the substrate 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS). The electroactive substrate ABTS can be also monitored by cyclic voltammetry, thus allowing for determination of the enzymatic activity electrochemically. It was found that the recombinant laccase exhibited higher activity as the temperature increased up to 65 °C. Spectroscopic studies of Tth-laccase based on circular dichroism and fluorescence measurements are consistent with a thermally stable secondary structure of the protein. Figure Electrochemically monitored activity of laccase immobilized on a glassy carbon electrode increases as a function of temperature.

Keywords: Thermus thermophilus ; Laccase; Electrochemistry; Thermophilic; Enzyme

Enhanced detection of olefins using ambient ionization mass spectrometry: Ag⁺ adducts of biologically relevant alkenes by Ayanna U. Jackson; Thomas Shum; Ewa Sokol; Allison Dill; R. Graham Cooks (pp. 367-376).

Spray solvent doped with silver ions increases the ease of olefin detection by desorption electrospray ionization (DESI). Characteristic silver adducts were generated in up to 50 times greater abundance when compared to conventional DESI spray solvents for the biologically significant olefin, arachidonic acid, in the positive ion mode. In the analysis of 26 lipids, silver adduct formation was highly favorable for fatty acids, fatty acid esters and prostaglandins but not applicable to some other classes (e.g., polar lipids such as ceramide and its derivative cerebroside sulfate). An investigation exploring competitive Ag⁺ cationization with a mixture of components demonstrated that polyunsaturated compounds form Ag⁺ adducts most readily. Silver cationization allowed the distinction between three sets of isomers in the course of multiple-stage collision-induced dissociation, so providing insight into the location of the olefin bonds. A silver ion-doped solvent was used in DESI imaging of normal and tumor canine bladder tissue sections. The Ag⁺ fatty acid adducts permitted post facto differentiation between the normal and tumor regions. In addition, silver adduct formation in the course of DESI imaging of tissue sections revealed the presence of triacylglycerides, a class of compounds not previously identified through DESI imaging. A simple silver nitrate spray solvent has the potential to further improve DESI analysis of unsaturated biomolecules and other molecules containing π-bonds through selective silver cationization. Figure Schematic of the experimental setup for the desorption electrospray ionization (DESI) mass spectrometry analysis. Spray solvent doped with silver ions increases the ease of olefin detection by DESI.

Keywords: Fatty acid; Fatty acid ethyl ester; Tissue imaging; Arachidonic acid; Oleic acid; Prostaglandin E1; Lipids; Glycerides; Mass spectrometry imaging

Multilayer gold nanoparticle-assisted protein tryptic digestion in solution and in gel under photothermal heating by Jen-Yi Chen; Kar-Wei Hon; Yu-Chie Chen (pp. 377-385).

Elevating the reaction temperature is an effective method to accelerate protein enzymatic digestion because it can promote protein denaturation and enzyme activities. In this study, we demonstrated a new photothermal heating method to assist protein tryptic digestion on glass slides. A glass slide coated with layer-by-layer gold nanoparticles (Glass@AuNPs), combined with the use of a near infrared (NIR) diode laser, was used to raise reaction temperature during tryptic digestion in a short period of time. The modified glass slide is capable of absorbing NIR light arising from the dipole–dipole interactions between Au NPs immobilized on the slide. The temperature of Glass@AuNPs rapidly increased when irradiated by the NIR laser, accelerating protein enzymatic digestion conducted on the slide. Thus, when performing the tryptic digestion of proteins on the Glass@AuNPs slide under NIR irradiation, 3.5 min was sufficient to carry out the tryptic digestion of proteins in solution, while less than 5 min was adequate for in-gel tryptic digestion of proteins. Matrix-assisted laser desorption/ionization mass spectrometry was used for characterization of the tryptic digestion product. On the basis of the results, the time taken to analyze proteins could be greatly reduced using this current approach. Figure A new photothermal heating method to assist protein tryptic-digestion on glass slides coated with layer-by-layer gold nanoparticles (Glass@AuNPs), combined with the use of a near infrared (NIR) diode laser, was demonstrated. MALDI MS was used for characterization of the resultant peptides

Keywords: Gold NPs; Tryptic digestion; Photothermal; MALDI-MS

Metabolic fingerprinting as a tool to monitor whole-cell biotransformations by Catherine L. Winder; Robert Cornmell; Stephanie Schuler; Roger M. Jarvis; Gill M. Stephens; Royston Goodacre (pp. 387-401).

Fourier transform infrared (FT-IR) spectroscopy was employed as a rapid high-throughput phenotypic typing technique to generate metabolic fingerprints of Escherichia coli MG1655 pDTG601A growing in fed-batch culture, during the dioxygenase-catalysed biotransformation of toluene to toluene cis-glycol. With toluene fed as a vapour, the final toluene cis-glycol concentration was 83 mM, whereas the product concentration was only 22 mM when the culture was supplied with liquid toluene. Multivariate statistical analysis employing cluster analysis was used to analyse the dynamic changes in the data. The analysis revealed distinct trends and trajectories in cluster ordination space, illustrating phenotypic changes related to differences in the growth and product formation of the cultures. In addition, partial least squares regression was used to correlate the FT-IR metabolic fingerprints with the levels of toluene cis-glycol and acetate, the latter being an indicator of metabolic stress. We propose that this high-throughput metabolic fingerprinting approach is an ideal tool to assess temporal biochemical dynamics in complex biological processes, as demonstrated by this redox biotransformation. Moreover, this approach can also give useful information on product yields and fermentation health indicators directly from the fermentation broth without the need for lengthy chromatographic analysis of the products.

Keywords: Fourier transform infrared spectroscopy; Escherichia coli ; Biocatalysis; Metabolomics; Toluene cis-glycol; Fed-batch culture

An implantable biochip to influence patient outcomes following trauma-induced hemorrhage by Anthony Guiseppi-Elie (pp. 403-419).

Following hemorrhage-causing injury, lactate levels rise and correlate with the severity of injury and are a surrogate of oxygen debt. Posttraumatic injury also includes hyperglycemia, with continuously elevated glucose levels leading to extensive tissue damage, septicemia, and multiple organ dysfunction syndrome. A temporary, implantable, integrated glucose and lactate biosensor and communications biochip for physiological status monitoring during hemorrhage and for intensive care unit stays has been developed. The dual responsive, amperometric biotransducer uses the microdisc electrode array format upon which were separately immobilized glucose oxidase and lactate oxidase within biorecognition layers, 1.0–5.0 μm thick, of 3 mol% tetraethyleneglycol diacrylate cross-linked p(HEMA-co-PEGMA-co-HMMA-co-SPA)-p(Py-co-PyBA) electroconductive hydrogels. The device was then coated with a bioactive hydrogel layer containing phosphoryl choline and polyethylene glycol pendant moieties [p(HEMA-co-PEGMA-co-HMMA-co-MPC)] for indwelling biocompatibility. In vitro cell proliferation and viability studies confirmed both polymers to be non-cytotoxic; however, PPy-based electroconductive hydrogels showed greater RMS 13 and PC12 proliferation compared to controls. The glucose and lactate biotransducers exhibited linear dynamic ranges of 0.10–13.0 mM glucose and 1.0–7.0 mM and response times (t ₉₅) of 50 and 35–40 s, respectively. Operational stability gave 80% of the initial biosensor response after 5 days of continuous operation at 37 °C. Preliminary in vivo studies in a Sprague–Dawley hemorrhage model showed tissue lactate levels to rise more rapidly than systematic lactate. The potential for an implantable biochip that supports telemetric reporting of intramuscular lactate and glucose levels allows the refinement of resuscitation approaches for civilian and combat trauma victims. Figure Schematic of an electrode-supported, two-layer hydrogel membrane for bioreceptor hosting and tissue biocompatibility

Keywords: Biosensors; Biochips; Biointerfaces; Electroconductive hydrogels; Trauma; Hemorrhage

Kinetic and mechanistic studies of the photolysis of metronidazole in simulated aqueous environmental matrices using a mass spectrometric approach by Lei Tong; Sandra Pérez; Carlos Gonçalves; Fátima Alpendurada; Yanxin Wang; Damià Barceló (pp. 421-428).

Metronidazole is a nitroimidazole antibiotic derivative used in humans against anaerobic bacteria and protozoa. In light of the recent detection of metronidazole in hospital wastes, sewage treatment plants, and surface waters, along with its known sensitivity toward photolytical degradation, this study aimed to model the photolysis in environmental waters by sunlight as a natural attenuation process. To this end, the degradation of metronidazole in a photoreactor simulating solar radiation (Suntest CPS) was compared in five different aqueous matrices: deionized water, artificial freshwater (AFW), AFW supplemented with nitrate (5 mg/L), AFW containing humic acids, and AFW with both nitrate and humic acids. Irrespective of the test medium, the degradation of the metronidazole solutions (10 and 0.02 mg/L) was found to follow pseudo-first-order kinetics. Degradation rates were dependant on the matrix, with humic acids causing a two to threefold decrease in the rate constants while the presence of nitrate had no marked effect on the kinetics. Therefore, the direct photolysis of metronidazole was apparently attenuated through a filter effect of humic acids. Screening of the irradiated water samples by ultra performance liquid chromatography/quadrupole time-of-flight mass spectrometry allowed separation and characterisation of four principal phototransformation products of the antibiotic. The high-resolution MS data pointed to the formation of two rearrangement products (C₆H₁₀N₃O₃) isobaric with metronidazole, a third product deriving from the elimination of NO from the nitro group (C₆H₁₁N₂O₂), and a fourth unidentified degradate with a likely elemental composition of C₅H₁₀N₃O.

Keywords: Photolysis; Pharmaceuticals; Structure elucidation; LC-QqToF-MS; Environment

Quantification of isotope-labelled and unlabelled folates in plasma, ileostomy and food samples by Barbara E. Büttner; Veronica E. Öhrvik; Cornelia M. Witthöft; Michael Rychlik (pp. 429-439).

New stable isotope dilution assays were developed for the simultaneous quantitation of [¹³C₅]-labelled and unlabelled 5-methyltetrahydrofolic acid, 5-formyltetrahydrofolic acid, folic acid along with unlabelled tetrahydrofolic acid and 10-formylfolic acid in clinical samples deriving from human bioavailability studies, i.e. plasma, ileostomy samples, and food. The methods were based on clean-up by strong anion exchange followed by LC-MS/MS detection. Deuterated analogues of the folates were applied as the internal standards in the stable isotope dilution assays. Assay sensitivity was sufficient to detect all relevant folates in the respective samples as their limits of detection were below 0.62 nmol/L in plasma and below 0.73 μg/100 g in food or ileostomy samples. Quantification of the [¹³C₅]-label in clinical samples offers the possibility to differentiate between folate from endogenous body pools and the administered dose when executing bioavailability trials. Figure Differentiation of folate isotopologues by tandem mass spectrometry

Keywords: Folate; Ileostomal effluent; Plasma; LC-MS/MS; Stable isotope dilution assay

Comparison of the duplex-destabilizing effects of nucleobase-caged oligonucleotides by Alexandre Rodrigues-Correia; Martin B. Koeppel; Florian Schäfer; K. B. Joshi; Timo Mack; Alexander Heckel (pp. 441-447).

Nucleobase-caged oligonucleotide residues have photolabile “caging groups” that prevent the formation of Watson–Crick base pairs until the unmodified nucleobase is restored in a photolysis event. This principle can be used to put a growing variety of powerful nucleic acid-based applications under the precise spatiotemporal control using light as an addressing mechanism. Examples for applications include light control of transcription, RNAi, nucleic acid folding, primer extension, and restriction endonuclease as well as DNAzyme, aptamer, and antisense activity. However, a comparison of the duplex-destabilization properties of the various caged residues that have been used up to date and rules for achieving a maximal duplex destabilization with a minimum amount of modified residues are still missing. We present both a comparison of the duplex-destabilizing capabilities of various nucleobase-caged residues and address the question of influence on neighboring base pairs. Figure Nucleobase-caged nucleosides act as mismatches until irradiation with UV light which cleaves off the caging group. This technology allows to add spatiotemporal control over nucleic acid-based applications. This study provides a first systematic evaluation of residues that have been presented in individual studies over the recent years and tries to establish rules for their optimal use.

Keywords: Nucleic acids; Caged compounds; DNA duplex stability; DNA duplex melting temperature

Selective extraction of nitroaromatic explosives by using molecularly imprinted silica sorbents by Sonia Lordel; Florence Chapuis-Hugon; Véronique Eudes; Valérie Pichon (pp. 449-458).

Two molecularly imprinted silicas (MISs) were synthesized and used as selective sorbents for the extraction of nitroaromatic explosives in post-blast samples. The synthesis of the MISs was carried out with phenyltrimethoxysilane as monomer, 2,4-dinitrotoluene (2,4-DNT) as template and triethoxysilane as cross-linker by a sol–gel approach in two molar ratios: 1/4/20 and 1/4/30 (template/monomer/cross-linker). Non-imprinted silica sorbents were also prepared following the same procedures without introducing the template. An optimized procedure dedicated to the selective treatment of aqueous samples was developed for both MISs for the simultaneous extraction of the template and other nitroaromatic compounds commonly used as explosives. The capacity of the MISs was measured by the extraction of increasing amounts of 2,4-DNT in pure water and is higher than 3.2 mg/g of sorbent for each MIS. For the first time, four nitroaromatic compounds were selectively extracted and determined simultaneously with extraction recoveries higher than 79%. The potential of these sorbents was then highlighted by their use for the clean-up of post-blast samples (motor oil, post-mortem blood, calcined fragments, etc.). The results were compared to those obtained using a conventional sorbent, thus demonstrating the interest of the use of these MISs as selective sorbents.

Keywords: Nitroaromatic explosives; Molecularly imprinted silica; Sol–gel approach; Solid phase extraction

Analysis of nitrated proteins and tryptic peptides by HPLC-chip-MS/MS: site-specific quantification, nitration degree, and reactivity of tyrosine residues by Yingyi Zhang; Hong Yang; Ulrich Pöschl (pp. 459-471).

The reaction products and pathways of protein nitration were studied with bovine serum albumin (BSA) and ovalbumin (OVA) nitrated by liquid tetranitromethane (TNM) or by gaseous nitrogen dioxide and ozone (NO₂ + O₃). Native and nitrated proteins were enzymatically digested with trypsin, and the tryptic peptides were analyzed by high-performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS) using a chip cube nano-flow system (Agilent). Upon nitration by TNM, up to ten of 17 tyrosine residues in BSA and up to five of ten tyrosine residues in OVA could be detected in nitrated form. Upon nitration by NO₂ + O₃, only three nitrated tyrosine residues were found in BSA. The nitration degrees of individual nitrotyrosine residues (ND_Y) were determined by site-specific quantification and compared to the total protein nitration degrees (ND) determined by photometric detection of HPLC-DAD. The slopes of the observed linear correlations between ND_Y and ND varied in the range of ~0.02–2.4 for BSA and ~0.2–1.6 for OVA. They provide information about the relative rates of nitration or reaction probabilities for different tyrosine residues. In BSA, the tyrosine residue Y₁₆₁ was by far most reactive against NO₂ + O₃ and one of the four most reactive positions with regard to nitration by TNM. In OVA, all except one tyrosine residue detected in nitrated form exhibited similar reactivities. The observed nitration patterns show how the site selectivity of protein nitration depends on the nitrating agent, reaction conditions, and molecular structure of the protein (primary, secondary, and tertiary).

Keywords: Proteins and peptides; BSA; OVA; Nitrotyrosine; HPLC-chip-MS/MS; Site selectivity

Synthesis and analytical characterisation of copper-based nanocoatings for bioactive stone artworks treatment by Nicoletta Ditaranto; Sabrina Loperfido; Inez van der Werf; Annarosa Mangone; Nicola Cioffi; Luigia Sabbatini (pp. 473-481).

Biological agents play an important role in the deterioration of cultural heritage causing aesthetic, biogeophysical and biogeochemical damages. Conservation is based on the use of preventive and remedial methods. The former aims at inhibiting biological attack, and the latter aims at eradicating the biological agents responsible for biodeterioration. Here, we propose the preparation and the analytical characterisation of copper-based nanocoating, capable of acting both as a remedy and to prevent microbial proliferation. Core–shell CuNPs are mixed with a silicon-based product, commonly used as a water-repellent/consolidant, to obtain a combined bioactive system to be applied on stone substrates. The resulting coatings exert a marked biological activity over a long period of time due to the continuous and controlled release of copper ions acting as biocides. To the best of our knowledge, this is the first time that a multifunctional material is proposed, combining the antimicrobial properties of nanostructured coatings with those of the formulations applied to the restoration of stone artworks. A complete characterisation based on a multi-technique analytical approach is presented. Online abstract figure Release properties and morphological features of copper-based nanocoatings.

Keywords: Copper nanocomposites; Biocidal remedy; Cultural heritage; XPS; Stone artworks

Comparison of two liquid-state NMR methods for the determination of saccharides in carrot (Daucus carota L.) roots by Linda Weberskirch; Alan Luna; Sara Skoglund; Hervé This (pp. 483-487).

In order to determine the saccharide content of plant tissues, we studied a new non-destructive and fast analytical method that we call “direct quantitative proton nuclear magnetic resonance spectroscopy” (d q ¹H NMR): the application of quantitative proton nuclear magnetic resonance spectroscopy (q ¹H NMR) to non modified plant tissues along with capillary tubes containing a reference compound (for quantification) and deuterium oxide (for locking). Using this method, the saccharide content of samples of carrot (Daucus carota L.) roots was compared to the results given from similar samples by the formerly published q ¹H NMR determination of extracts obtained by the O'Donoghue/Davis method. The content in glucose and sucrose is significantly higher with the direct method than when an extraction step is included; the content in fructose is not significantly different. If a possible detection of saccharides included in glycosylated biological compounds is to be excluded, a more complete extraction of saccharides is probably obtained using the direct method.

Keywords: NMR/ESR; Foods/beverages; Natural products; Organic compounds/trace organic compounds

Calibration and uncertainty assessment for certified reference gas mixtures by Franklin R. Guenther; Antonio Possolo (pp. 489-500).

The weighted least squares method to build an analysis function described in ISO 6143, Gas analysis—Comparison methods for determining and checking the composition of calibration gas mixtures, is modified to take into account the typically small number of instrumental readings that are obtained for each primary standard gas mixture used in calibration. The theoretical basis for this modification is explained, and its superior performance is illustrated in a simulation study built around a concrete example, using real data. The corresponding uncertainty assessment is obtained by application of a Monte Carlo method consistent with the guidance in the Supplement 1 to the Guide to the expression of uncertainty in measurement, which avoids the need for two successive applications of the linearizing approximation of the conventional method for uncertainty propagation. The three main steps that NIST currently uses to certify a reference gas mixture (homogeneity study, calibration, and assignment of value and uncertainty assessment), are described and illustrated using data pertaining to an actual standard reference material.

Keywords: Calibration; Gas mixture; Certified reference material; Errors-in-variables; Generalized least squares; Maximum likelihood; Statistical bootstrap; Outliers; Coverage intervals

Position-resolved determination of trace elements in mandibular gnathobases of the Antarctic copepod Calanoides acutus using a multimethod approach by Kai Bechstein; Jan Michels; Jürgen Vogt; Gregor C. Schwartze; Carla Vogt (pp. 501-508).

Previous studies have revealed silica formation in the teeth of mandibular gnathobases of copepods while significant amounts of zinc and copper are present, which might improve mechanical stability of the teeth and represent an adaptation to compact food particles. The present study aimed at analysing the distribution and concentration of trace elements in the mandibular gnathobases of females of the Antarctic copepod species Calanoides acutus. Because of the low overall masses of few micrograms per specimen the application of a combination of position-resolved micro-beam techniques was necessary and micro-particle-induced X-ray emission spectrometry and laser ablation inductively coupled plasma mass spectrometry were used to determine Ba, Br, Ca, Cl, Cu, Fe, K, Mg, Na, Ni, P, S, Si and Zn in the samples with μm to sub-μm resolution. Calibration strategies were optimised to fit for the carbonate matrix. The analyses revealed a distinct enrichment of Br, Ca, Fe, K, S, Si and Zn in the teeth of the gnathobases. Figure Elemental distribution in chitinous material from copepod gnathobases, measured by PIXE.

Keywords: Copepods; Mandibular gnathobase; μ-PIXE; LA-ICP-MS; Calibration

Elemental analysis of a single-wall carbon nanotube candidate reference material by R. Zeisler; R. L. Paul; R. Oflaz Spatz; L. L. Yu; J. L. Mann; W. R. Kelly; B. E. Lang; S. D. Leigh; J. Fagan (pp. 509-517).

A material containing single-wall carbon nanotubes (SWCNTs) with other carbon species, catalyst residues, and trace element contaminants has been prepared by the National Institute of Standards and Technology for characterization and distribution as Standard Reference Material SRM 2483 Carbon Nanotube Soot. Neutron activation analysis (NAA) and inductively coupled plasma mass spectrometry (ICP–MS) were selected to characterize the elemental composition. Catalyst residues at percentage mass fraction level were determined with independent NAA procedures and a number of trace elements, including selected rare earth elements, were determined with NAA and ICP–MS procedures. The results of the investigated materials agreed well among the NAA and ICP–MS procedures and good agreement of measured values with certified values was found in selected SRMs included in the analyses. Based on this work mass fraction values for catalyst and trace elements were assigned to the candidate SRM.

Keywords: Carius tube digestion; Inductively coupled plasma mass spectrometry; Instrumental neutron activation analysis; Prompt gamma activation analysis; Rare earth elements; Value assignment

Integrated microfluidic device for the separation and electrochemical detection of catechol estrogen-derived DNA adducts by Abdulilah Dawoud Bani-Yaseen; Toshikazu Kawaguchi; Alexander K. Price; Christopher T. Culbertson; Ryszard Jankowiak (pp. 519-524).

Catechol estrogen-derived DNA adducts are formed as a result of the reaction of catechol estrogen metabolites (e.g., catechol estrogen quinones) with DNA to form depurinating adducts. Developing a new methodology for the detection of various DNA adducts is essential for medical diagnostics, and to this end, we demonstrate the applicability of on-chip capillary electrophoresis with an integrated electrochemical system for the separation and amperometric detection of various catechol estrogen-derived DNA adducts. A hybrid PDMS/glass microchip with in-channel amperometric detection interfaced with in situ palladium decoupler is utilized and presented. The influence of buffer additives along with the effect of the separation voltage on the resolving power of the microchip is discussed. Calibration plots were constructed in the range 0.4–10 μM with r ² ≥ 0.999, and detection limits in the attomole range are reported. These results suggest that on-chip analysis is applicable for analyzing various DNA adducts as potential biomarkers for future medical diagnostics.

Keywords: Microfluidic device; Catechol estrogens; Amperometric detection; DNA adduct; Separation; Integration

Sections

Personal tools

Analytical and Bioanalytical Chemistry (v.399, #1)

Sections

Personal tools

Local resources

Analytical and Bioanalytical Chemistry (v.399, #1)