Analytical and Bioanalytical Chemistry (v.410, #17)

received her Ph.D. (1974) and D.Sc. (1996) degrees in chemistry from M.V. Lomonosov Moscow State University (MSU). She is a full chair professor in analytical chemistry in the Department of Chemistry, MSU. She is also Head of the Commission on Teaching Analytical Chemistry in Russian Universities and Head of the Commission on Biochemical Methods of Analysis of the Scientific Council on Analytical Chemistry of the Russian Academy of Sciences. Her research interests include basic studies and applications of enzymatic methods of analysis.

Vitamin B3 mystery challenge by Lucia D’Ulivo (3925-3926).

Solution to collision induced dissociation mass spectrometry challenge by Daniel G. Beach; Wojciech Gabryelski (3927-3930).

Water analysis has been an important area since the beginning of analytical chemistry. The focus though has shifted substantially: from minerals and the main constituents of water in the time of Carl Remigius Fresenius to a multitude of, in particular, organic compounds at concentrations down to the sub-nanogram per liter level nowadays. This was possible only because of numerous innovations in instrumentation in recent decades, drivers of which are briefly discussed. In addition to the high demands on sensitivity, high throughput by automation and short analysis times are major requirements. In this article, some recent developments in the chemical analysis of organic micropollutants (OMPs) are presented. These include the analysis of priority pollutants in whole water samples, extension of the analytical window, in particular to encompass highly polar compounds, the trend toward more than one separation dimension before mass spectrometric detection, and ways of coping with unknown analytes by suspect and nontarget screening approaches involving high-resolution mass spectrometry. Furthermore, beyond gathering reliable concentration data for many OMPs, the question of the relevance of such data for the aquatic system under scrutiny is becoming ever more important. To that end, effect-based analytics can be used and may become part of future routine monitoring, mostly with a focus on adverse effects of OMPs in specific test systems mimicking environmental impacts. Despite advances in the field of water analysis in recent years, there are still many challenges for further analytical research. Graphical abstractRecent trends in water analysis of organic micropollutants that open new opportunities in future water monitoring. HRMS high-resolution mass spectrometry, PMOC persistent mobile organic compounds
Keywords: Water analysis; Organic micropollutants; Effect-based analysis; High-resolution mass spectrometry; Multidimensional chromatography; Ion mobility

Surface plasmon resonance (SPR) has become a well-recognized label-free technique for measuring the binding kinetics between biomolecules since the invention of the first SPR-based immunosensor in 1980s. The most popular and traditional format for SPR analysis is to monitor the real-time optical signals when a solution containing ligand molecules is flowing over a sensor substrate functionalized with purified receptor molecules. In recent years, rapid development of several kinds of SPR imaging techniques have allowed for mapping the dynamic distribution of local mass density within single living cells with high spatial and temporal resolutions and reliable sensitivity. Such capability immediately enabled one to investigate the interaction between important biomolecules and intact cells in a label-free, quantitative, and single cell manner, leading to an exciting new trend of cell-based SPR bioanalysis. In this Trend Article, we first describe the principle and technical features of two types of SPR imaging techniques based on prism and objective, respectively. Then we survey the intact cell-based applications in both fundamental cell biology and drug discovery. We conclude the article with comments and perspectives on the future developments. Graphical abstractRecent developments in surface plasmon resonance (SPR) imaging techniques allow for label-free mapping the mass-distribution within single living cells, leading to great expansions in biomolecular interactions studies from homogeneous substrates functionalized with purified biomolecules to heterogeneous substrates containing individual living cells
Keywords: Surface plasmon resonance (SPR); Biosensor; Label-free; Cell biology; Drug discovery

In my 2010 review, I addressed conventional water analysis and biosensing of organic pollutants in Japan between 1960s and 2000s. It is now timely to reexamine current analytical and biomonitoring approaches in view of the new challenges in assessing pollution, particularly in closed water bodies, as pollutants tend to accumulate in these endorheic basins. In the present review series, I presented current water environment and its microbial biosensors. In this part, I presented current data of the water quality of these water bodies in Japan and established the need to further develop microbial biosensor technologies to address and monitor water quality here. Graphical AbstractCurrent water pollution indirectly occurring by anthropogenic eutrophication (Part I).
Keywords: Review; Water quality investigation; Water pollution; Organic pollution; Anthropogenic eutrophication; Toxification

In Part I of the present review series, I presented the current state of the water environment by focusing on Japanese cases and discussed the need to further develop microbial biosensor technologies for the actual water environment. I comprehensively present trends after approximately 2010 in microbial biosensor development for the water environment. In the first section, after briefly summarizing historical studies, recent studies on microbial biosensor principles are introduced. In the second section, recent application studies for the water environment are also introduced. Finally, I conclude the present review series by describing the need to further develop microbial biosensor technologies. Graphical abstractCurrent water pollution indirectly occurs by anthropogenic eutrophication (Part I). Recent trends in microbial biosensor development for water environment are described in part II of the present review series.
Keywords: Comprehensive review; Microbial biosensor; Environmental biosensor; Organic pollution; Eutrophication; Toxicity

Synthesis and application of magnetic molecularly imprinted polymers in sample preparation by Shuyao Huang; Jianqiao Xu; Jiating Zheng; Fang Zhu; Lijun Xie; Gangfeng Ouyang (3991-4014).
Magnetic molecularly imprinted polymers (MMIPs) have superior advantages in sample pretreatment because of their high selectivity for target analytes and the fast and easy isolation from samples. To meet the demand of both good magnetic property and good extraction performance, MMIPs with various structures, from traditional core–shell structures to novel composite structures with a larger specific surface area and more accessible binding sites, are fabricated by different preparation technologies. Moreover, as the molecularly imprinted polymer (MIP) layers determine the affinity, selectivity, and saturated adsorption amount of MMIPs, the development and innovation of the MIP layer are attracting attention and are reviewed here. Many studies that used MMIPs as sorbents in dispersive solid-phase extraction of complex samples, including environmental, food, and biofluid samples, are summarized. Graphical abstractThe application of magnetic molecularly imprinted polymers (MIPs) in the sample preparation procedure improves the analytical performances for complex samples. MITs molecular imprinting technologies
Keywords: Magnetic molecularly imprinted polymers; Sample preparation; Complex samples; Dispersive solid-phase extraction; Selective extraction

MALDI matrices for low molecular weight compounds: an endless story? by Cosima Damiana Calvano; Antonio Monopoli; Tommaso R. I. Cataldi; Francesco Palmisano (4015-4038).
Since its introduction in the 1980s, matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) has gained a prominent role in the analysis of high molecular weight biomolecules such as proteins, peptides, oligonucleotides, and polysaccharides. Its application to low molecular weight compounds has remained for long time challenging due to the spectral interferences produced by conventional organic matrices in the low m/z window. To overcome this problem, specific sample preparation such as analyte/matrix derivatization, addition of dopants, or sophisticated deposition technique especially useful for imaging experiments, have been proposed. Alternative approaches based on second generation (rationally designed) organic matrices, ionic liquids, and inorganic matrices, including metallic nanoparticles, have been the object of intense and continuous research efforts. Definite evidences are now provided that MALDI MS represents a powerful and invaluable analytical tool also for small molecules, including their quantification, thus opening new, exciting applications in metabolomics and imaging mass spectrometry. This review is intended to offer a concise critical overview of the most recent achievements about MALDI matrices capable of specifically address the challenging issue of small molecules analysis. Graphical abstractAn ideal Book of matrices for MALDI MS of small molecules
Keywords: Mass spectrometry; Low molecular weight compounds; Metabolomics; MALDI matrices

The number of genetically modified organisms (GMOs) on the market is steadily increasing. Because of regulation of cultivation and trade of GMOs in several countries, there is pressure for their accurate detection and quantification. Today, DNA-based approaches are more popular for this purpose than protein-based methods, and real-time quantitative PCR (qPCR) is still the gold standard in GMO analytics. However, digital PCR (dPCR) offers several advantages over qPCR, making this new technique appealing also for GMO analysis. This critical review focuses on the use of dPCR for the purpose of GMO quantification and addresses parameters which are important for achieving accurate and reliable results, such as the quality and purity of DNA and reaction optimization. Three critical factors are explored and discussed in more depth: correct classification of partitions as positive, correctly determined partition volume, and dilution factor. This review could serve as a guide for all laboratories implementing dPCR. Most of the parameters discussed are applicable to fields other than purely GMO testing. Graphical abstractThere are generally three different options for absolute quantification of genetically modified organisms (GMOs) using digital PCR: droplet- or chamber-based and droplets in chambers. All have in common the distribution of reaction mixture into several partitions, which are all subjected to PCR and scored at the end-point as positive or negative. Based on these results GMO content can be calculated.
Keywords: Digital PCR; Droplet digital PCR; Chip-based digital PCR; Genetically modified organisms; Quantification

Proteomic approaches beyond expression profiling and PTM analysis by Jiaqi Fu; Mei Wu; Xiaoyun Liu (4051-4060).
Essentially, all cellular functions are executed by proteins. Different physiological and pathological conditions dynamically control various properties of proteins, including expression levels, post-translational modifications (PTMs), protein–protein interactions, enzymatic activity, etc. Thus far, the vast majority of proteomic efforts have been focused on quantitative profiling of protein abundance/expression and their PTMs. In this article, we review some recent exciting progress in the development of proteomic approaches to examine protein functions from perspectives other than expression levels and PTMs. Specifically, we discuss advancements in proximity-based labeling, analysis of protein termini and newly synthesized proteins, and activity-based protein profiling.
Keywords: Proximity-based labeling; Terminal proteomics; Newly synthesized proteins; Activity-based protein profiling

Ambient desorption/ionization mass spectrometry: evolution from rapid qualitative screening to accurate quantification tool by Jacob T. Shelley; Sunil P. Badal; Carsten Engelhard; Heiko Hayen (4061-4076).
In this article, some recent trends and developments in ambient desorption/ionization mass spectrometry (ADI-MS) are reviewed, with a special focus on quantitative analyses with direct, open-air sampling. Accurate quantification with ADI-MS is still not routinely performed, but this aspect is considered of utmost importance for the advancement of the field. In fact, several research groups are devoted to the development of novel and optimized ADI-MS approaches. Some key trends include novel sample introduction strategies for improved reproducibility, tailored sample preparation protocols for removing the matrix and matrix effects, and multimode ionization sources. In addition, there is significant interest in quantitative mass spectrometry imaging. Graphical abstractConceptual diagram of the ambient desorption/ionization mass spectrometry approach with different desorption/ionization probes
Keywords: Ambient mass spectrometry; Quantification; Internal standard; Matrix effects; Mass spectrometry imaging; ADI-MS

Distributed electrochemical sensors: recent advances and barriers to market adoption by Rafael Hoekstra; Pascal Blondeau; Francisco J. Andrade (4077-4089).
Despite predictions of their widespread application in healthcare and environmental monitoring, electrochemical sensors are yet to be distributed at scale, instead remaining largely confined to R&D labs. This contrasts sharply with the situation for physical sensors, which are now ubiquitous and seamlessly embedded in the mature ecosystem provided by electronics and connectivity protocols. Although chemical sensors could be integrated into the same ecosystem, there are fundamental issues with these sensors in the three key areas of analytical performance, usability, and affordability. Nevertheless, advances are being made in each of these fields, leading to hope that the deployment of automated and user-friendly low-cost electrochemical sensors is on the horizon. Here, we present a brief survey of key challenges and advances in the development of distributed electrochemical sensors for liquid samples, geared towards applications in healthcare and wellbeing, environmental monitoring, and homeland security. As will be seen, in many cases the analytical performance of the sensor is acceptable; it is usability that is the major barrier to commercial viability at this moment. Were this to be overcome, the issue of affordability could be addressed. Graphical Abstractᅟ
Keywords: Electrochemical sensors; Autonomous sensing; Ultralow-cost diagnostics; Distributed sensing networks; Remote sensing

Tools for detecting insect semiochemicals: a review by Alexandra Nava Brezolin; Janine Martinazzo; Daniela Kunkel Muenchen; Alana Marie de Cezaro; Aline Andressa Rigo; Clarice Steffens; Juliana Steffens; Maria Carolina Blassioli-Moraes; Miguel Borges (4091-4108).
Semiochemicals are chemical compounds that are released by many species as a means of intra- and interspecific communication. Insects have extremely advanced olfactory systems; indeed, they rely on smell when performing many of their main behaviors, such as oviposition, breeding, prey location, and defense. This characteristic of insects implies that semiochemicals could be used for various applications, including in agriculture, where they could be employed along with other tools to control pest insects. The aim of this review is to present the main techniques used and the state of the art in the detection of semiochemicals, focusing on pheromones. In addition to the traditional methods of identifying semiochemicals, such as gas chromatography coupled to a high-resolution detection mode (e.g., flame ionization (FID), electron capture (ECD), photoionization (PID), or mass spectrometry (MS)), other tools are addressed in this review, including sensors and biosensors. While these new technologies may be used under laboratory conditions to improve or complement technologies that are already being used, they are mainly intended for use as new agricultural tools for detecting and controlling pest insects in the field.
Keywords: Agriculture; Biosensors; Pest insects; Insect pheromones

is a research scientist at the R&D Department of XanTec bioanalytics GmbH, Germany, and a Ph.D. student at the Department of Chemistry of the University of Duisburg-Essen, Germany. He is working on the development and functionalization of polymer-based biosensor coatings and novel biocompatible coatings for biomedical applications. is CEO and cofounder of XanTec bioanalytics GmbH, a company that develops and manufactures biochips for the label-free analysis of biomolecular interactions. Before he joined XanTec, he received his M.Sc. from the University of Muenster, Germany, and served as research associate with the Institute of Chemical and Biochemical Sensor Research (ICB), where he developed biosensors and biocompatible coatings. He is author of several publications, book contributions, and patents in the field of optical and electrochemical biosensors, microfluidics, fluorophore technology, and surface science. is a professor at the Department of Chemistry of the University of Duisburg-Essen, Germany, and the CEO of the Textile Research Institute (DTNW) in Krefeld, Germany. He is working on the functionalization and characterization of polymer surfaces with polymer brushes, hydrogels, block copolymers, and polyelectrolytes in order to achieve novel functional materials via tailored surface modification. The carbodiimide-mediated amine coupling of protein ligands to sensor chips coated with anionic polycarboxylate hydrogels, such as carboxymethyl dextran, is the predominant covalent immobilization procedure utilized in optical biosensors, namely surface plasmon resonance (SPR) biosensors. Usually, electrostatic interactions at a slightly acidic pH and low ionic strength are employed to efficiently accumulate neutral and basic ligands on the chip surface, which are then covalently coupled by surface-bound active N-hydroxysuccinimide (NHS) esters. Unfortunately, this approach is not suitable for acidic proteins or other ligands with low isoelectric points (IEPs), such as nucleic acids, because the charge density of the polycarboxylates is greatly reduced at acidic pH or because electrostatic attraction cannot be achieved. To overcome these drawbacks, we have established a charge-reversal approach that allows the preconcentration of acidic proteins above their IEPs. A precisely controlled amount of tertiary amines is applied to reverse the previous anionic surface charge while maintaining carbodiimide compatibility with future protein immobilization. The mechanism of this reversed-charge immobilization approach was demonstrated employing protein A as a model protein and using attenuated total reflectance Fourier transform infrared spectroscopy, dynamic contact angle measurements, colorimetric quantification, and SPR analysis to characterize surface derivatization. Furthermore, even though it had previously proven impossible to preconcentrate DNA electrostatically and to covalently couple it to polyanionic chip surfaces, we demonstrated that our approach allowed DNA to be preconcentrated and immobilized in good yields. Graphical abstractPrinciple of the covalent immobilization of acidic ligands on reversed-charge zwitterionic sensor chip surfaces
Keywords: Optical biosensor; SPR; Carbodiimide chemistry; Reversed-charge preconcentration; DNA coupling

A versatile and sensitive lateral flow immunoassay for the rapid diagnosis of visceral leishmaniasis by Laura Anfossi; Fabio Di Nardo; Margherita Profiti; Chiara Nogarol; Simone Cavalera; Claudio Baggiani; Cristina Giovannoli; Giulia Spano; Ezio Ferroglio; Walter Mignone; Sergio Rosati (4123-4134).
is an associate professor at the Department of Chemistry, University of Turin, and works in the forensic, analytical and bioanalytical laboratories. She has been working for several years on the development of immunological methods of analysis in several formats and for disparate applications (food safety, clinics, veterinary). Her research interest is new strategies and new materials for point-of-need tests based on lateral flow assay technology. is a postdoctoral research fellow at the Department of Chemistry, University of Turin. One of his main research interests is the development of rapid immunological methods of analysis, especially those based on the lateral flow immunoassay technique. is a research technician at the Infectious Diseases Unit of the Department of Veterinary Sciences, University of Turin, Italy. She has expertise in molecular techniques for the characterisation of viral proteins and the expression of recombinant protein. works for In3Diagnostic s.r.l. as the Quality Control and Research Unit manager. She has experience in ready-to-use ELISA optimization as well as ISO and certification procedures for diagnostic methods in veterinary medicine. is a Ph.D. student at the Department of Chemistry, University of Turin; he works in the forensic, analytical and bioanalytical laboratories. His research interest is the development of rapid immunological devices for therapeutic drug monitoring. is an associate professor at the Department of Chemistry, University of Turin, where he works in the forensic, analytical and bioanalytical laboratories. He has gained experience in the design of molecularly imprinted biomimetic receptors applied in the development of selective analytical methods for contaminants in complex samples. is an associate professor at the Department of Chemistry, University of Turin, where she works in the forensic, analytical, and bioanalytical laboratories. She has gained experience in the development of immunological methods and in the preparation and application of polymeric materials for the selective recognition of compounds in food and environmental contamination analysis. is a Ph.D. student in chemical and materials science at the Department of Chemistry, University of Turin. She was trained in organic chemistry for her thesis work during her master’s degree. She currently utilizes that training in analytical chemistry research, focusing in particular on molecularly imprinted polymers and other technologies applied in molecular recognition. is a full professor of parasitology and parasitic diseases at the Department of Veterinary Sciences of the University of Turin, Italy. He has been involved in research projects relating to the diagnosis, epidemiology, and pathogenesis of parasites of livestock, pets, and honey bees and of wildlife diseases of public health interest. is the team leader of the S.S. Sezione di Imperia of the Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta. His main experience is in entomology, cetacean pathology, and wild ungulate diseases. is a full professor of infectious diseases at the Department of Veterinary Sciences of the University of Turin, Italy. He main research focus is on the development of a diagnostic assay based on recombinant protein for several animal diseases, including zoonosis. Visceral leishmaniasis (VL) is a zoonotic infectious disease with a severe impact on humans and animals. Infection is transmitted by phlebotomine sand flies, and several domestic and wild mammals act as reservoirs for the infection, so the prompt detection of infected hosts is crucial to preventing and controlling the spread of the disease and its transmission to humans. A rapid and portable tool for VL diagnosis based on the lateral flow immunoassay (LFIA) technology is described herein. The device exploits a highly specific chimeric recombinant antigen as the recognition element for capturing anti-leishmanial antibodies, and protein A labelled with gold nanoparticles as the signal reporter. The LFIA shows excellent diagnostic sensitivity (98.4%), specificity (98.9%), and agreement with serological reference methods for diagnosing canine VL. The long-term stability of the LFIA device was confirmed based on six months of storage at room temperature or 4 °C, and the qualitative response of the device was not affected by limited thermal stress. The use of the broadly specific protein A means that the LFIA can be readily adapted to diagnose VL in dogs (the main reservoir for human infection) and other mammals, thus further assisting efforts to control the spread of VL. Graphical abstractA rapid and portable diagnostic tool for visceral leishmaniasis (VL) based on lateral flow immunoassay (LFIA) technology. The presence of anti-leishmanial antibodies is revealed through the binding of these antibodies to a highly specific chimeric antigen. Employing a broadly specific signal reporter (protein A labelled with gold nanoparticles) enables the LFIA to be easily adapted to diagnose VL in different animals
Keywords: Immunochromatographic test; Validation; Point-of-care test; Shelf-life; Fox; Cat

received her B.S. in chemistry and forensic chemistry from Lake Superior State University, Sault Ste. Marie, Michigan. She is currently a graduate student studying analytical chemistry under the supervision of Professor Jared L. Anderson at Iowa State University. Her research involves the application of magnetic ionic liquids towards nucleic acid analysis. completed his B.A. degree in chemistry at Gustavus Adolphus College (Minnesota) in 2012. He is a Ph.D. candidate in analytical chemistry at Iowa State University under the supervision of Professor Jared Anderson. His research focuses on selective nucleic acid analysis and the application of magnetic ionic liquids in bioanalytical chemistry. completed her M.S. in Forensic Science at Sam Houston State University in 2013. She is currently a graduate student at Iowa State University in the Department of Chemistry. Her research focuses on mass spectral imaging of latent fingerprints in Dr. Young Jin Lee’s group. In the summer of 2016, she completed a summer research internship with Professor Jared Anderson. is Professor of Chemistry in the Department of Chemistry at Iowa State University. His research focuses on the development of stationary phases for multidimensional gas chromatography, alternative approaches in sample preparation, particularly in nucleic acid isolation and purification, and developing analytical tools for trace level analysis within active pharmaceutical ingredients. Nucleic acid extraction and purification represents a major bottleneck in DNA analysis. Traditional methods for DNA purification often require reagents that may inhibit quantitative polymerase chain reaction (qPCR) if not sufficiently removed from the sample. Approaches that employ magnetic beads may exhibit lower extraction efficiencies due to sedimentation and aggregation. In this study, four hydrophobic magnetic ionic liquids (MILs) were investigated as DNA extraction solvents with the goal of improving DNA enrichment factors and compatibility with downstream bioanalytical techniques. By designing custom qPCR buffers, we directly incorporated DNA-enriched MILs including trihexyl(tetradecyl)phosphonium tris(hexafluoroacetylaceto)nickelate(II) ([P6,6,6,14 +][Ni(hfacac)3 ]), [P6,6,6,14 +] tris(hexafluoroacetylaceto)colbaltate(II) ([Co(hfacac)3 ]), [P6,6,6,14 +] tris(hexafluoroacetylaceto)manganate(II) ([Mn(hfacac)3 ]), or [P6,6,6,14 +] tetrakis(hexafluoroacetylaceto)dysprosate(III) ([Dy(hfacac)4 ]) into reaction systems, thereby circumventing the need for time-consuming DNA recovery steps. Incorporating MILs into the reaction buffer did not significantly impact the amplification efficiency of the reaction (91.1%). High enrichment factors were achieved using the [P6,6,6,14 +][Ni(hfacac)3 ] MIL for the extraction of single-stranded and double-stranded DNA with extraction times as short as 2 min. When compared to a commercial magnetic bead-based platform, the [P6,6,6,14 +][Ni(hfacac)3 ] MIL was capable of producing higher enrichment factors for single-stranded DNA and similar enrichment factors for double-stranded DNA. The MIL-based method was applied for the extraction and direct qPCR amplification of mutation prone-KRAS oncogene fragment in plasma samples. Graphical abstractMagnetic ionic liquid solvents are shown to preconcentrate sufficient KRAS DNA template from an aqueous solution in as short as 2 min without using chaotropic salts or toxic organic solvents. By using custom-designed qPCR buffers, DNA can be directly amplified and quantified from four MILs examined in this study.
Keywords: Magnetic ionic liquid; Nucleic acids (DNA | RNA); PCR; qPCR; Cell-free DNA

In this work, a novel simple fluorescent biosensor for the highly sensitive and selective detection of adrenaline was established. Firstly, water-soluble CuInS2 quantum dots (QDs) capped by L-Cys were synthesized via a hydrothermal synthesis method. Then, the positively charged adrenaline was assembled on the surface of CuInS2 QDs due to the electrostatic interactions and hydrogen bonding, which led to the formation of adrenaline-CuInS2 QD (Adr-CuInS2 QD) electrostatic complexes. Tyrosinase (TYR) can catalyze adrenaline to generate H2O2, and additionally oxidize the adrenaline to adrenaline quinone. Both the H2O2 and the adrenaline quinone can quench the fluorescence of the CuInS2 QDs through the electron transfer (ET) process. Thus, the determination of adrenaline could be facilely achieved by taking advantage of the fluorescence “turn off” feature of CuInS2 QDs. Under the optimum conditions, the fluorescence quenching ratio I f/I f0 (I f and I f0 were the fluorescence intensity of Adr-CuInS2 QDs in the presence and absence of TYR, respectively) was proportional to the logarithm of adrenaline concentration in the range of 1 × 10−8–1 × 10−4 mol L−1 with the detection limit of 3.6 nmol L−1. The feasibility of the proposed biosensor in real sample assay was also studied and satisfactory results were obtained. Significantly, the proposed fluorescent biosensor can also be utilized to screen TYR inhibitors. Graphical abstractSchematic illustration of the fluorescent biosensor for adrenaline detection (A) and tyrosinase inhibitor screening (B).
Keywords: Fluorescence biosensor; Adrenaline; Tyrosinase; Inhibitor screening; Quantum dots

Isotope ratio measurements have been conducted on a series of isotopically distinct pure CO2 gas samples using the technique of dual-inlet isotope ratio mass spectrometry (DI-IRMS). The influence of instrumental parameters, data normalization schemes on the metrological traceability and uncertainty of the sample isotope composition have been characterized. Traceability to the Vienna PeeDee Belemnite(VPDB)-CO2 scale was realized using the pure CO2 isotope reference materials(IRMs) 8562, 8563, and 8564. The uncertainty analyses include contributions associated with the values of iRMs and the repeatability and reproducibility of our measurements. Our DI-IRMS measurement system is demonstrated to have high long-term stability, approaching a precision of 0.001 parts-per-thousand for the 45/44 and 46/44 ion signal ratios. The single- and two-point normalization bias for the iRMs were found to be within their published standard uncertainty values. The values of 13C/12C and 18O/16O isotope ratios are expressed relative to VPDB-CO2 using the δ13CVPDB−CO2 $$ {delta}^{13}{C}_{VPDB-{CO}_2} $$ and δ18OVPDB−CO2 $$ {delta}^{18}{O}_{VPDB-{CO}_2} $$ notation, respectively, in parts-per-thousand (‰ or per mil). For the samples, value assignments between (−25 to +2) ‰ and (−33 to −1) ‰ with nominal combined standard uncertainties of (0.05, 0.3) ‰ for δ13CVPDB−CO2 $$ {delta}^{13}{C}_{VPDB-{CO}_2} $$ and δ18OVPDB−CO2 $$ {delta}^{18}{O}_{VPDB-{CO}_2} $$, respectively were obtained. These samples are used as laboratory reference to provide anchor points for value assignment of isotope ratios (with VPDB traceability) to pure CO2 samples. Additionally, they serve as potential parent isotopic source material required for the development of gravimetric based iRMs of CO2 in CO2-free dry air in high pressure gas cylinder packages at desired abundance levels and isotopic composition values. Graphical abstractCO2 gas isotope ratio metrology
Keywords: Isotope metrology; Isotope reference material; SI traceability; VPDB-CO2 traceability; δ 13C; DI-IRMS

During the last decades, the quality of aquatic ecosystems has been threatened by increasing levels of pollutions, caused by the discharge of man-made chemicals, both via accidental release of pollutants as well as a consequence of the constant outflow of inadequately treated wastewater effluents. For this reason, the European Union is updating its legislations with the aim of limiting the release of emerging contaminants. The Commission Implementing Decision (EU) 2015/495 published in March 2015 drafts a “Watch list” of compounds to be monitored Europe-wide. In this study, a methodology based on online solid-phase extraction (SPE) ultra-high-performance liquid chromatography coupled to a triple-quadrupole mass spectrometer (UHPLC-MS/MS) was developed for the simultaneous determination of the 17 compounds listed therein. The proposed method offers advantages over already available methods, such as versatility (all 17 compounds can be analyzed simultaneously), shorter time required for analysis, robustness, and sensitivity. The employment of online sample preparation minimized sample manipulation and reduced dramatically the sample volume needed and time required, dramatically the sample volume needed and time required, thus making the analysis fast and reliable. The method was successfully validated in surface water and influent and effluent wastewater. Limits of detection ranged from sub- to low-nanogram per liter levels, in compliance with the EU limits, with the only exception of EE2. Graphical abstractSchematic of the workflow for the analysis of the Watch list compounds.
Keywords: EU Watch list; Online preconcentration; Ultra-high-performance liquid chromatography; Online SPE; UHPLC-MS/MS; Water samples

The research described here provides the most comprehensive qualitative characterization of three combustion-related standard reference materials (SRMs) for polycyclic aromatic sulfur heterocycles (PASHs) and some alkyl-substituted (alkyl-) derivatives to date: SRM 1597a (coal tar), SRM 1991 (coal tar/petroleum extract), and SRM 1975 (diesel particulate extract). An analytical approach based on gas chromatography/mass spectrometry (GC/MS) is presented for the determination of three-, four-, and five-ring PASH isomers and three- and four-ring alkyl-PASHs in the three SRM samples. The benefit of using a normal-phase liquid chromatography (NPLC) fractionation procedure prior to GC/MS analysis was demonstrated for multiple isomeric PASH groups. Using a semi-preparative aminopropyl (NH2) LC column, the three combustion-related samples were fractionated based on the number of aromatic carbon atoms. The NPLC-GC/MS method presented here allowed for the following identification breakdown: SRM 1597a – 35 PASHs and 59 alkyl-PASHs; SRM 1991–31 PASHs and 58 alkyl-PASHs; and SRM 1975–13 PASHs and 25 alkyl-PASHs. These identifications were based on NPLC retention data, the GC retention times of reference standards, and the predominant molecular ion peak in the mass spectrum. Prior to this study, only 11, 1, and 0 PASHs/alkyl-PASHs had been identified in SRM 1597a, SRM 1991, and SRM 1975, respectively. Graphical abstractNPLC-GC/MS analysis for the three- and four-ring parent PASH isomers in SRM 1597a.
Keywords: Polycyclic aromatic sulfur heterocycles; Gas chromatography/mass spectrometry; Normal-phase liquid chromatography fractionation; Standard Reference Materials; Coal tar; Diesel particulate

Identification of methylated tubulin through analysis of methylated lysine by Rika Suzuki; Takashi Funatsu; Makoto Tsunoda (4189-4194).
Post-translational modifications to tubulin such as acetylation and detyrosination play important roles in microtubule functions. Methylation is an important post-translational modification; however, to date, few methylated tubulins have been identified. In the present study, we developed a method for analyzing methylated lysine with the aim of identifying methylated tubulin. This method involves four steps: (1) acid hydrolysis of tubulin into amino acids, (2) selective extraction of methylated lysine using a monolithic-silica disk-packed spin column, (3) fluorescence derivatization of methylated lysine with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), and (4) separation of NBD-methylated lysine on a column consisting of C18, cation and anion ligand, and fluorescence detection. Using the newly developed method, the dimethylation of lysine in tubulin was identified. This new method could be applied to searches for other methylated proteins.
Keywords: Post-translational modification; Methylated lysine; Fluorescence; Mixed-mode

Aberrant glycosylation has been commonly observed in various physiological and pathological disorders (including cancers), and quite a few glycoproteins have been approved by the US Food and Drug Administration (FDA) as markers for early diagnosis. Each glycoprotein may have multiple glycoforms, and cancer-related ones can be only some specific glycoforms which have much higher sensitivity and specificity; for example, AFP glycoform AFP-L3 with N-glycan of 01Y(61F)41Y41M(31M41Y41L41S61M41Y41L41S is of bigger diagnostic value for hepatocellular carcinoma than total AFP (i.e., combination of all glycoforms). Mass spectrometry-based glycomics is currently the state-of-the-art instrumental analytical pipeline for high-throughput characterization of various glycoforms, where not only monosaccharide composition but also comprehensive structural information (sequence and linkage) of N-glycans are now reported thanks to our recently developed N-glycan database search engine GlySeeker. With this new capability, here, we report our large-scale characterization of human liver N-glycome with primary structures; 214 unique N-glycans with unique primary structures were identified and visualized with spectrum-level false discovery rate ≤ 1% and number of best hits of 1. The LO2 N-glycans reported here serve as a basic reference for future liver N-glycome study, and further quantitative analysis will enable characterization of differentially expressed N-glycans and discovery of more effective markers for liver and other diseases. Data are available via ProteomeXchange with identifier PXD008158.
Keywords: Human liver N-glycome; LO2 cells; Primary structure; Identification; Visualization

Triacetone triperoxide (TATP) is frequently used in improvised explosive devices because of its ease of manufacture and tremendous explosive force. In this paper, we describe a new method for detection of TATP, thermal decomposition peroxy radical chemical amplification cavity ring-down spectroscopy (TD-PERCA-CRDS). In this method, air is sampled through a heated inlet to which ~ 1 ppmv nitric oxide (NO) is added. To verify the purity of synthetic standards, the mid-infrared spectrum of TATP vapor was recorded. The thermal decomposition of TATP is shown to produce radicals which oxidize NO to nitrogen dioxide (NO2), whose concentration increase is monitored by optical absorption at 405 nm using a blue diode laser CRDS. The sensitivity could be improved through addition of ~ 1% ethane (C2H6), which fuels catalytic conversion of NO to NO2. The limit of detection of TD-PERCA-CRDS with respect to TATP is 22 pptv (1 s data), approximately six orders of magnitude below TATP’s saturation vapor pressure. Insights into the mechanism of TATP thermal decomposition, TD-PERCA-CRDS interferences, and the suitability of TD-PERCA-CRDS as a peroxy radical explosive detection method at security check points are discussed.
Keywords: Triacetone triperoxide (TATP); Trace sensing; Peroxy radical chemical amplification (PERCA); Cavity ring-down spectroscopy (CRDS); Mechanism of TATP thermal decomposition; Mid-infrared spectrum

Online screening of α-amylase inhibitors by capillary electrophoresis by Ondřej Hodek; Tomáš Křížek; Pavel Coufal; Helena Ryšlavá (4213-4218).
Pancreatic α-amylase plays an important role in dietary starch hydrolysis in the small intestine and participates in enhanced glucose concentration after meals. It seems to be a problem for diabetic patients, who suffer from longer postprandial hyperglycemia after meal consumption than healthy people. There are commercially available drugs that inhibit α-amylase and thus reduce the postprandial hyperglycemia effect. However, these drugs may cause severe side effects. Conversely, some naturally occurring flavonoids were suggested to have an α-amylase-inhibiting effect without any side effects. There had been no rapid, undemanding method in terms of sample and reagent preparation that would enable screening of many potential inhibitors. Therefore, we developed an online capillary electrophoresis method to monitor α-amylase activity in the presence of an inhibitor. Each reaction constituent was introduced separately, directly into a capillary where the reagents were mixed by diffusion, which resulted in a 5-min analysis including conditioning of the capillary. We applied the method to test the inhibitory effect of flavonoid standards and their mixture and we investigated the inhibitory effect of ethanolic extract from Betula pendula bark. The developed method presents a faster and less expensive alternative to previously described offline methods. Graphical abstractOnline CE screening of α-amylase inhibitors
Keywords: α-Amylase; Capillary zone electrophoresis; Online enzyme assays; Starch

Rapid detection of the neonicotinoid insecticide imidacloprid using a quenchbody assay by Shitao Zhao; Jinhua Dong; Hee-Jin Jeong; Koichi Okumura; Hiroshi Ueda (4219-4226).
Contamination of the land and water by neonicotinoid insecticide residues is currently a severe environmental problem. However, the traditional methods for pesticide residue analysis are time consuming and laborious. To tackle this problem, here we describe a novel quenchbody (Q-body) immunoassay reagent that allows the rapid and sensitive detection of imidacloprid, one of the most frequently used neonicotinoid pesticides, in aqueous solution. A Q-body comprises an antibody Fab fragment that is site-specifically labeled with a fluorescent dye. The Fab fragment quenches the dye with its internal tryptophan residues via photoinduced electron transfer. The subsequent addition of imidacloprid stabilizes the antibody structure and displaces the quenched dye to the outside of the protein, resulting in increased fluorescence. The constructed Q-body assay exhibited a high dynamic range and a low limit of detection (10 ng mL−1), and the entire assay procedure could be completed in a few minutes. The assay showed a low cross-reactivity with possible interfering analogous compounds, indicating that it has a good selectivity. Hence, the developed Q-body assay has excellent potential as a universal technology for monitoring neonicotinoid residues in environmental and food samples. Graphical abstractA novel quenchbody (Q-body) immunoassay reagent that allows the rapid and sensitive detection of imidacloprid, one of the most frequently used neonicotinoid pesticides, in aqueous solution was developed. The addition of imidacloprid stabilizes the Q-body structure and displaces the quenched dye to the outside of the protein, resulting in increased fluorescence. The constructed Q-body assay exhibited a high dynamic range and a low limit of detection (10 ng mL−1), and completed in a few minutes.
Keywords: Neonicotinoid; Colony collapsing disorder; Immunoassay; On-site monitoring; Biosensors

Novel and label-free colorimetric detection of radon using AuNPs and lead(II)-induced GR5 DNAzyme-based amplification strategy by Hongwen Liu; Yating Chen; Chunli Song; Gang Tian; Shiya Li; Guiying Yang; Changyin Lv (4227-4234).
Radioactive radon decays into a stable daughter product, 210Pb, which was used as the detection target to determine the radon radiation dose in a new technique. Pb2+ triggers DNAzyme to cleave a molecular beacon (MB), resulting in the stem–loop structure opening and forming two single DNA strands (ssDNA). The ssDNA binds to unmodified gold nanoparticles and effectively prevents their aggregation in a salt solution. The detached enzyme strands continue to complement the remaining MB to amplify the response signal. The method proposed in this study exhibited a good linear relationship for Pb2+ and radon concentrations in the range of 6.22 × 102–1.02 × 105 Bq h/m3 with a detection limit of 186.48 Bq h/m3 using an ultraviolet–visible spectrometer. In practical applications, this sensitive method can avoid radioactive damage in field testing, and the detection limit meets the national standard in China. Importantly, this simple, highly sensitive strategy uses simple equipment and has a strong anti-interference ability. Graphical abstract
Keywords: DNAzyme; Gold nanoparticles; Lead; Radon; Spectrophotometry

Correction to: Precise, accurate and user-independent blood collection system for dried blood spot sample preparation by Ricardo Neto; Andrew Gooley; Michael C. Breadmore; Emily F. Hilder; Florian Lapierre (4235-4235).
The authors would like to call the reader’s attention to the following: The instrument they used to measure the volumetric precision of the dispensing devices is not called “VMS” but “PCS®”.