Analytical and Bioanalytical Chemistry (v.407, #20)
Peter Fabian and Martin Dameris: Ozone in the atmosphere: basic principles, natural and human impacts by Thorsten Hoffmann (5861-5862).
Aerosols and health: a challenge for chemical and biological analysis by Ralf Zimmermann (5863-5867).
is Full Professor of Analytical Chemistry at the University of Rostock (UR) and also Head of the Cooperation Group “Comprehensive Molecular Analytics (CMA)” at the Helmholtz Zentrum München (HMGU). The Chair of Analytical Chemistry and the CMA together represent the Joint Mass Spectrometry Centre of UR and HMGU (JMSC, www.jmsc.de ), which is also headed by Professor Zimmermann. Currently he is spokesperson of an international consortium, the Helmholtz Virtual Institute of Complex Molecular Systems in Environmental Health – Aerosols and Health (HICE, www.hice-vi.eu ), which is investigating health effects of combustion aerosols by the integrated analysis on chemical and physical emission aerosol properties and molecular biological effects in aerosol exposed human lung cell models. His research interests include instrumental development and application of photoionization mass spectrometry, comprehensive multidimensional chromatography, industrial process analysis, applied combustion research, and aerosol analysis as well as metabolomics and analyses of biological effects in lung cell models.
Comparative chemistry and toxicity of diesel and biomass combustion emissions by M. Ian Gilmour; Yong Ho Kim; Michael D. Hays (5869-5875).
is a toxicologist and Chief of the Cardiopulmonary and Immunotoxicology Branch at the United States Environmental Protection Agency. He has over 20 years of research experience in the field of pulmonary immunity associated with air-pollutant exposures and subsequent development of allergic and infectious lung disease. His current research interests include health risks of short and long-term exposures to biomass combustion smoke. is a National Research Council Senior Research Associate in the Cardiopulmonary and Immunotoxicology Branch at the United States Environmental Protection Agency. He has extensive experience in mechanistic investigation of transport of inhaled particles across pulmonary epithelium. His current research interests focus on health effects of biomass smoke depending on different fuel types or combustion conditions. is a physical scientist in the Emissions Characterization and Prevention Branch at the United States Environmental Protection Agency. He has more than 15 years of research experience in the analytical and chemical characterization of fine particulate matter (PM2.5) emissions from a wide range of combustion-related air pollution sources, including heavy-duty diesel engines, aircraft turbine engines, and biomass fires. His current research interests are at the interface of analytical chemistry and toxicology.
Methods for characterization of organic compounds in atmospheric aerosol particles by Jevgeni Parshintsev; Tuulia Hyötyläinen (5877-5897).
Atmospheric aerosol particles of primary or secondary, biogenic or anthropogenic origin are highly complex samples of changing composition in time and space. To assess their effects on climate or human health, the size-dependent chemical composition of these ubiquitous atmospheric constituents must be known. The development of novel analytical methods has enabled more detailed characterization of the organic composition of aerosols. This review gives an overview of the methods used in the chemical characterization of atmospheric aerosol particles, with a focus on mass-spectrometry techniques for organic compounds, either alone or in combination with chromatographic separation. Off-line, on-site, and on-line methods are covered, and the advantages and limitations of the different methods are discussed. The main emphasis is on methods used for detailed characterization of the composition of the organic compounds in aerosol particles. We address and summarize the current state of analytical methods used in aerosol research and discuss the importance of developing novel sampling strategies and analytical instrumentation. Graphical Abstract Challenges in the atmospheric aerosol analytics
Keywords: Atmospheric aerosols; Sampling; Analysis; Mass spectrometry; On-site analysis; On-line analysis
Single-particle speciation of alkylamines in ambient aerosol at five European sites by Robert M. Healy; Greg J. Evans; Michael Murphy; Berko Sierau; Jovanna Arndt; Eoin McGillicuddy; Ian P. O’Connor; John R. Sodeau; John C. Wenger (5899-5909).
Alkylamines are associated with both natural and anthropogenic sources and have been detected in ambient aerosol in a variety of environments. However, little is known about the ubiquity or relative abundance of these species in Europe. In this work, ambient single-particle mass spectra collected at five sampling sites across Europe have been analysed for their alkylamine content. The aerosol time-of-flight mass spectrometer (ATOFMS) data used were collected in Ireland (Cork), France (Paris, Dunkirk and Corsica) and Switzerland (Zurich) between 2008 and 2013. Each dataset was queried for mass spectral marker ions associated with the following ambient alkylamines: dimethylamine (DMA), trimethylamine (TMA), diethylamine (DEA), triethylamine (TEA), dipropylamine (DPA) and tripropylamine (TPA). The fraction of ambient particles that contained detectable alkylamines ranged from 1 to 17 % depending on location, with the highest fractions observed in Paris and Zurich in the winter months. The lowest fractions were observed at coastal sites, where the influence of animal husbandry-related alkylamine emissions is also expected to be lowest. TMA was the most ubiquitous particle phase alkylamine detected and was observed at all locations. Alkylamines were found to be internally mixed with both sulphate and nitrate for each dataset, suggesting that aminium salt formation may be important at all sites investigated. Interestingly, in Corsica, all alkylamine particles detected were also found to be internally mixed with methanesulphonic acid (MSA), indicating that aminium methanesulphonate salts may represent a component of marine ambient aerosol in the summer months. Internal mixing of alkylamines with sea salt was not observed, however. Alkylamine-containing particle composition was found to be reasonably homogeneous at each location, with the exception of the Corsica and Dunkirk sites, where two and four distinct mixing states were observed, respectively.
Keywords: Aerosols; Particulates; Agriculture; Speciation; Organic compounds; Trace organic compounds
Online determination of polycyclic aromatic hydrocarbon formation from a flame soot generator by Laarnie Mueller; Gert Jakobi; Juergen Orasche; Erwin Karg; Martin Sklorz; Gülcin Abbaszade; Benedict Weggler; Lianpeng Jing; Juergen Schnelle-Kreis; Ralf Zimmermann (5911-5922).
In this study, we produced a class of diffusion flame soot particles with varying chemical and physical properties by using the mini-Combustion Aerosol STandard (CAST) and applying varying oxidant gas flow rates under constant propane, quenching, and dilution gas supply. We varied the soot properties by using the following fuel-to-air equivalence ratios (Φ): 1.13, 1.09, 1.04, 1.00, 0.96, and 0.89. Within this Φ range, we observed drastic changes in the physical and chemical properties of the soot. Oxidant-rich flames (Φ < 1) were characterized by larger particle size, lower particle number concentration, higher black carbon (BC) concentration, lower brown carbon BrC.[BC]−1 than fuel-rich flames (Φ > 1). To investigate the polycyclic aromatic hydrocarbons (PAH) formation online, we developed a new method for quantification by using the one 13C-containing doubly charged PAH ion in a high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS). The time-resolved concentration showed that the larger PAHs prevailed in the fuel-rich flames and diminished in the oxidant-rich flames. By comparison with the offline in situ derivatization-thermal-desorption gas-chromatography time-of-flight mass spectrometry (IDTD-GC-ToF-MS), we found that the concentration by using the HR-ToF-AMS was underestimated, especially for lower mass PAHs (C14–C18) in the fuel-rich flames possibly due to size limitation and degradation of semi-volatile species under high vacuum and desorption temperature in the latter. For oxidant-rich flames, the large PAHs (C20 and C22) were detected in the HR-ToF-AMS while it was not possible in IDTD-GC-ToF-MS due to matrix effect. The PAH formation was discussed based on the combination of our results and with respect to Φ settings.
Keywords: Aerosols/particulates; Online analytical method; Doubly charge isotope ion; PAH formation; Soot
Characterisation of ship diesel primary particulate matter at the molecular level by means of ultra-high-resolution mass spectrometry coupled to laser desorption ionisation—comparison of feed fuel, filter extracts and direct particle measurements by Christopher P. Rüger; Martin Sklorz; Theo Schwemer; Ralf Zimmermann (5923-5937).
In this study, positive-mode laser desorption-ionisation ultra-high-resolution mass spectrometry (LDI-FT-ICR-MS) was applied to study combustion aerosol samples obtained from a ship diesel engine as well as the feed fuel, used to operate the engine. Furthermore, particulate matter was sampled from the exhaust tube using an impactor and analysed directly from the impaction foil without sample treatment. From the high percentage of shared sum formula as well as similarities in the chemical spread of aerosol and heavy fuel oil, results indicate that the primary aerosol mainly consists of survived, unburned species from the feed fuel. The effect of pyrosynthesis could be observed and was slightly more pronounced for the CH-class compared to other compound classes, but in summary not dominant. Alkylation pattern as well as the aromaticity distribution, using the double bond equivalent, revealed a shift towards lower alkylation state for the aerosol. The alkylation pattern of the most dominant series revealed a higher correlation between different aerosol samples than between aerosol and feed samples. This was confirmed by cluster analysis. Overall, this study shows that LDI-FT-ICR-MS can be successfully applied for the analysis of combustion aerosol at the molecular level and that sum formula information can be used to identify chemical differences between aerosol and fuel as well as between different size fractions of the particulate matter.
Keywords: Ship emissions; High-resolution mass spectrometry (HR-MS); Heavy fuel oil; Aerosol; Particulate matter (PM); Laser desorption ionisation (LDI)
Real-time analysis of organic compounds in ship engine aerosol emissions using resonance-enhanced multiphoton ionisation and proton transfer mass spectrometry by Christian Radischat; Olli Sippula; Benjamin Stengel; Sophie Klingbeil; Martin Sklorz; Rom Rabe; Thorsten Streibel; Horst Harndorf; Ralf Zimmermann (5939-5951).
Organic combustion aerosols from a marine medium-speed diesel engine, capable to run on distillate (diesel fuel) and residual fuels (heavy fuel oil), were investigated under various operating conditions and engine parameters. The online chemical characterisation of the organic components was conducted using a resonance-enhanced multiphoton ionisation time-of-flight mass spectrometer (REMPI TOF MS) and a proton transfer reaction-quadrupole mass spectrometer (PTR-QMS). Oxygenated species, alkenes and aromatic hydrocarbons were characterised. Especially the aromatic hydrocarbons and their alkylated derivatives were very prominent in the exhaust of both fuels. Emission factors of known health-hazardous compounds (e.g. mono- and poly-aromatic hydrocarbons) were calculated and found in higher amounts for heavy fuel oil (HFO) at typical engine loadings. Lower engine loads lead in general to increasing emissions for both fuels for almost every compound, e.g. naphthalene emissions varied for diesel fuel exhaust between 0.7 mg/kWh (75 % engine load, late start of injection (SOI)) and 11.8 mg/kWh (10 % engine load, late SOI) and for HFO exhaust between 3.3 and 60.5 mg/kWh, respectively. Both used mass spectrometric techniques showed that they are particularly suitable methods for online monitoring of combustion compounds and very helpful for the characterisation of health-relevant substances. Graphical abstract Three-dimensional REMPI data of organic species in diesel fuel and heavy fuel oil exhaust
Keywords: Ship emissions; Poly-cyclic aromatic hydrocarbons; REMPI TOF MS; Heavy fuel oil; Diesel fuel
Assessing the role of chemical components in cellular responses to atmospheric particle matter (PM) through chemical fractionation of PM extracts by Jongbae Heo; Dagmara S. Antkiewicz; Martin M. Shafer; Dawn A. K. Perkins; Constantinos Sioutas; James J. Schauer (5953-5963).
In order to further our understanding of the influence of chemical components and ultimately specific sources of atmospheric particulate matter (PM) on pro-inflammatory and other adverse cellular responses, we promulgate and apply a suite of chemical fractionation tools to aqueous aerosol extracts of PM samples for analysis in toxicity assays. We illustrate the approach with a study that used water extracts of quasi-ultrafine PM (PM0.25) collected in the Los Angeles Basin. Filtered PM extracts were fractionated using Chelex, a weak anion exchanger diethylaminoethyl (DEAE), a strong anion exchanger (SAX), and a hydrophobic C18 resin, as well as by desferrioxamine (DFO) complexation that binds iron. The fractionated extracts were then analyzed using high-resolution sector field inductively coupled plasma mass spectrometry (SF-ICPMS) to determine elemental composition. Cellular responses to the fractionated extracts were probed in an in vitro rat alveolar macrophages model with measurement of reactive oxygen species (ROS) production and the cytokine tumor necrosis factor-α (TNF-α). The DFO treatment that chelates iron was very effective at reducing the cellular ROS activity but had only a small impact on the TNF-α production. In contrast, the hydrophobic C18 resin treatment had a small impact on the cellular ROS activity but significantly reduced the TNF-α production. The use of statistical methods to integrate the results across all treatments led to the conclusion that sufficient iron must be present to participate in the chemistry needed for ROS activity, but the amount of ROS activity is not proportional to the iron solution concentration. ROS activity was found to be most related to cationic mono- and divalent metals (i.e., Mn and Ni) and oxyanions (i.e., Mo and V). Although the TNF-α production was not significantly affected by the chelexation of iron, it was greatly impacted by the removal of organics with the C18 resin and all other metal removal methods, suggesting that iron is not a critical pathway leading to TNF-α production, but a wide range of soluble metals and organic compounds in particulate matter play a role. Although the results are specific to the Los Angeles Basin, where the samples used in the study were collected, the method employed in the study can be widely employed to study the role of components of particulate matter in in vitro or in vivo assays.
Keywords: Aerosols/particulates; Bioanalytical methods; Bioassays; Extraction (SFE | SPE | SPME); Mass spectrometry/ICP-MS
Differential proteomic analysis of mouse macrophages exposed to adsorbate-loaded heavy fuel oil derived combustion particles using an automated sample-preparation workflow by Tamara Kanashova; Oliver Popp; Jürgen Orasche; Erwin Karg; Horst Harndorf; Benjamin Stengel; Martin Sklorz; Thorsten Streibel; Ralf Zimmermann; Gunnar Dittmar (5965-5976).
Ship diesel combustion particles are known to cause broad cytotoxic effects and thereby strongly impact human health. Particles from heavy fuel oil (HFO) operated ships are considered as particularly dangerous. However, little is known about the relevant components of the ship emission particles. In particular, it is interesting to know if the particle cores, consisting of soot and metal oxides, or the adsorbate layers, consisting of semi- and low-volatile organic compounds and salts, are more relevant. We therefore sought to relate the adsorbates and the core composition of HFO combustion particles to the early cellular responses, allowing for the development of measures that counteract their detrimental effects. Hence, the semi-volatile coating of HFO-operated ship diesel engine particles was removed by stepwise thermal stripping using different temperatures. RAW 264.7 macrophages were exposed to native and thermally stripped particles in submersed culture. Proteomic changes were monitored by two different quantitative mass spectrometry approaches, stable isotope labeling by amino acids in cell culture (SILAC) and dimethyl labeling. Our data revealed that cells reacted differently to native or stripped HFO combustion particles. Cells exposed to thermally stripped particles showed a very differential reaction with respect to the composition of the individual chemical load of the particle. The cellular reactions of the HFO particles included reaction to oxidative stress, reorganization of the cytoskeleton and changes in endocytosis. Cells exposed to the 280 °C treated particles showed an induction of RNA-related processes, a number of mitochondria-associated processes as well as DNA damage response, while the exposure to 580 °C treated HFO particles mainly induced the regulation of intracellular transport. In summary, our analysis based on a highly reproducible automated proteomic sample-preparation procedure shows a diverse cellular response, depending on the soot particle composition. In particular, it was shown that both the molecules of the adsorbate layer as well as particle cores induced strong but different effects in the exposed cells.
Keywords: SILAC; Dimethyl labeling; Ship diesel exhaust particles; Polycyclic aromatic hydrocarbons; Oxidative stress; Mitochondria
Effects of an iron-based fuel-borne catalyst and a diesel particle filter on exhaust toxicity in lung cells in vitro by Sandro Steiner; Jan Czerwinski; Pierre Comte; Norbert V. Heeb; Andreas Mayer; Alke Petri-Fink; Barbara Rothen-Rutishauser (5977-5986).
Metal-containing fuel additives catalyzing soot combustion in diesel particle filters are used in a widespread manner, and with the growing popularity of diesel vehicles, their application is expected to increase in the near future. Detailed investigation into how such additives affect exhaust toxicity is therefore necessary and has to be performed before epidemiological evidence points towards adverse effects of their application. The present study investigates how the addition of an iron-based fuel additive (Satacen®3, 40 ppm Fe) to low-sulfur diesel affects the in vitro cytotoxic, oxidative, (pro-)inflammatory, and mutagenic activity of the exhaust of a passenger car operated under constant, low-load conditions by exposing a three-dimensional model of the human airway epithelium to complete exhaust at the air–liquid interface. We could show that the use of the iron catalyst without and with filter technology has positive as well as negative effects on exhaust toxicity compared to exhaust with no additives: it decreases the oxidative and, compared to a non-catalyzed diesel particle filter, the mutagenic potential of diesel exhaust, but increases (pro-)inflammatory effects. The presence of a diesel particle filter also influences the impact of Satacen®3 on exhaust toxicity, and the proper choice of the filter type to be used is of importance with regards to exhaust toxicity. Figure ᅟ
Keywords: Exhaust exposures; Iron catalyst; Diesel particle filter; 3D lung cell model; Air–liquid interface
Erratum to: Online determination of polycyclic aromatic hydrocarbon formation from a flame soot generator by Laarnie Mueller; Gert Jakobi; Juergen Orasche; Erwin Karg; Martin Sklorz; Gülcin Abbaszade; Benedict Weggler; Lianpeng Jing; Juergen Schnelle-Kreis; Ralf Zimmermann (5987-5987).
Profiling of adrenocorticotropic hormone and arginine vasopressin in human pituitary gland and tumor thin tissue sections using droplet-based liquid-microjunction surface-sampling-HPLC–ESI-MS–MS by Vilmos Kertesz; David Calligaris; Daniel R. Feldman; Armen Changelian; Edward R. Laws; Sandro Santagata; Nathalie Y. R. Agar; Gary J. Van Berkel (5989-5998).
PhD, is a Research Staff Scientist at the Oak Ridge National Laboratory. He received his PhD in 1997 in electrochemistry from Eotvos Lorand Science University, Budapest, Hungary. His research focuses on atmospheric-pressure surface-sampling and ionization methods for sensitive, automated, high-throughput analysis and chemical imaging of analytes on surfaces. PhD, is currently a postdoctoral researcher at Brigham and Women’s Hospital-Harvard Medical School. He received his PhD in Biochemistry from Aix-Marseille University, Marseille, France in 2011. His research focuses on biological mass spectrometry applied to cancer research. received his B.S. in chemistry and biology from Brandeis University in 2012. Following his undergraduate education, he worked as a research assistant in the Surgical Molecular Imaging Lab at Brigham and Women’s Hospital. He is currently pursuing a medical degree at Drexel University College of Medicine. received his B.A. in biological sciences from Northwestern University in 2014. He performed research as a visiting student at the McGovern Institute for Brain Research at MIT, focusing on the effect of differential gene expression in neurodegenerative disorders. He currently works as a technical research assistant in the Surgical Molecular Imaging Lab at Brigham and Women’s Hospital. MD, is the Director of the Pituitary and Neuroendocrine Center and Professor Emeritus of Neurological Surgery at Brigham and Women’s Hospital, Boston, MA. He received his doctoral degree from Johns Hopkins University School of Medicine, Baltimore, MD, and completed his residency at Johns Hopkins Hospital. His clinical interests include pituitary tumors, low-grade gliomas, malignant gliomas, craniopharyngioma, minimally invasive transnasal endoscopic pituitary surgery, and extended transsphenoidal surgery for parasellar tumors. MD PhD, is an Assistant Professor of Pathology at Harvard Medical School; neuropathologist at the Brigham and Women’s Hospital, and an Affiliated Member at the Broad Institute. He leads a laboratory at the Harvard Institute of Medicine on understanding the molecular pathology of brain tumors. He completed his MD, PhD at Mount Sinai Medical School of New York University in 2002 (New York, NY), and received a certificate of anatomic pathology and neuropathology from the American Board of Pathology in 2007. PhD, is the founding Director of the Surgical Molecular Imaging Laboratory (SMIL) in the Department of Neurosurgery at Brigham and Women’s Hospital, and Assistant Professor of Surgery and of Radiology at Harvard Medical School. Her multidisciplinary training includes a B.Sc. in Biochemistry (1997), PhD in Chemistry (2002), a postdoctoral fellowship in Neurology and Neurosurgery from McGill University, and further postdoctoral training in Neurosurgery at the Brigham and Women’s Hospital. From this unique background, she has developed a research program integrating approaches from chemistry to improve the care of patients affected by brain tumors. PhD, is a Distinguished Research Scientist and Leader of the Organic and Biological Mass Spectrometry Group at the Oak Ridge National Laboratory. He received his PhD in Analytical Chemistry from Washington State University, Pullman, WA in 1987. His research interests are in the subject of atmospheric-pressure-ionization-source fundamentals and ambient-based methods for surface sampling and ionization combined with mass spectrometry for chemical profiling and imaging of surfaces. Described here are the results from the profiling of the proteins arginine vasopressin (AVP) and adrenocorticotropic hormone (ACTH) from normal human pituitary gland and pituitary adenoma tissue sections, using a fully automated droplet-based liquid-microjunction surface-sampling-HPLC–ESI-MS–MS system for spatially resolved sampling, HPLC separation, and mass spectrometric detection. Excellent correlation was found between the protein distribution data obtained with this method and data obtained with matrix-assisted laser desorption/ionization (MALDI) chemical imaging analyses of serial sections of the same tissue. The protein distributions correlated with the visible anatomic pattern of the pituitary gland. AVP was most abundant in the posterior pituitary gland region (neurohypophysis), and ATCH was dominant in the anterior pituitary gland region (adenohypophysis). The relative amounts of AVP and ACTH sampled from a series of ACTH-secreting and non-secreting pituitary adenomas correlated with histopathological evaluation. ACTH was readily detected at significantly higher levels in regions of ACTH-secreting adenomas and in normal anterior adenohypophysis compared with non-secreting adenoma and neurohypophysis. AVP was mostly detected in normal neurohypophysis, as expected. This work reveals that a fully automated droplet-based liquid-microjunction surface-sampling system coupled to HPLC–ESI-MS–MS can be readily used for spatially resolved sampling, separation, detection, and semi-quantitation of physiologically-relevant peptide and protein hormones, including AVP and ACTH, directly from human tissue. In addition, the relative simplicity, rapidity, and specificity of this method support the potential of this basic technology, with further advancement, for assisting surgical decision-making. Graphical Abstract Mass spectrometry based profiling of hormones in human pituitary gland and tumor thin tissue sections
Keywords: Liquid microjunction; Droplet-based liquid extraction; Autosampler; Spatial distribution; Human pituitary; Protein; Adrenocorticotropic hormone (ACTH); AVP (vasopressin); Pituitary adenoma
Detection of tetrahydrocannabinol residues on hands by ion-mobility spectrometry (IMS). Correlation of IMS data with saliva analysis by Saskia Sonnberg; Sergio Armenta; Salvador Garrigues; Miguel de la Guardia (5999-6008).
is a second year Master’s student of Applied Chemistry and Biotechnology in the Tallinn University of Technology. During her Erasmus exchange studies she followed the Master’s Degree in Experimental Techniques in Chemistry and worked in the department of Analytical Chemistry in the University of Valencia. Previously, she obtained a Bachelor’s degree in Applied Chemistry and Biotechnology at the Tallinn University of Technology, defending her thesis on the topic: “The Impact of Nitric Oxide Donors on Platelets”. During her first year of Master’s studies she worked in The Competence Center of Food and Fermentation Technologies in Estonia. is Professor of the Analytical Chemistry Department of the University of Valencia (Spain). He obtained his PhD in Analytical Chemistry at the University of Valencia in 2006. His research topics included coupling of automated flow systems with infrared and Raman spectroscopy and the development of vibrational-spectroscopy-based methods combined with chemometrics for the quality control of commercial products. His current research is devoted to the development of fast and sensitive analytical methods based on ion-mobility spectrometry. has been Professor at the Department of Analytical Chemistry (University of Valencia, Spain) since 2006. His research has focused on sample preparation, mainly in the field of vibrational spectroscopy applied to quantitative analysis, combined with automation and the use of chemometrics. has been Full Professor at Valencia University (Department of Analytical Chemistry) since 1991. He has published numerous papers in the field of analytical chemistry related to sample preparation, automation, atomic and molecular spectroscopy, and chromatography. He has supervised 33 PhD theses and is a member of the Editorial board of TrEAC Trends in Environmental Analytical Chemistry (The Netherlands), Bioimpacts (Iran), Spectroscopy Letters (USA), Current Green Chemistry (United Arab Emirates), Ciencia (Venezuela), J. Braz. Chem. Soc. (Brazil), Journal of Analytical Methods in Chemistry and Chemical Speciation & Bioavailability (UK), SOP Transactions on Nano-technology (USA), and SOP Transactions on Analytical Chemistry (USA). Ion-mobility spectroscopy (IMS) was evaluated as a high-throughput, cheap, and efficient analytical tool for detecting residues of tetrahydrocannabinol (THC) on hands. Regarding the usefulness of hand residues as potential samples for determining THC handling and abuse, we studied the correlation between data obtained from cannabis consumers who were classified as positive after saliva analysis and from those who were classified as positive on the basis of the information from hand-residue analysis. Sampling consisted of wiping the hands with borosilicate glass microfiber filters and introducing these directly into the IMS after thermal desorption. The possibility of false positive responses, resulting from the presence of other compounds with a similar drift time to THC, was evaluated and minimised by applying the truncated negative second-derivative algorithm. The possibility of false negative responses, mainly caused by competitive ionisation resulting from nicotine, was also studied. Graphical abstract THC residues: from hands to analytical signals
Keywords: Tetrahydrocannabinol; THC; Ion-mobility spectrometry; Cannabis manipulation; Hand residues; Saliva
Critical evaluation of indirect methods for the determination of deoxynivalenol and its conjugated forms in cereals by Alexandra Malachová; Lenka Štočková; Astrid Wakker; Elisabeth Varga; Rudolf Krska; Herbert Michlmayr; Gerhard Adam; Franz Berthiller (6009-6020).
studied analytical chemistry at the Department of Food Analysis and Nutrition, Faculty of Food and Biochemical Technology of the University of Chemistry and Technology (UCT Prague), Czech Republic. She received her PhD degree in 2012. Currently, she works as a post-doc in the Christian Doppler Laboratory for Mycotoxin Metabolism and the Center for Analytical Chemistry at the Department of Agrobiotechnology (IFA-Tulln) of the University of Natural Resources and Life Sciences, Vienna (BOKU). She is an expert in LC-MS, including high-resolution MS. Her main field of expertise is the development, optimization, and validation of LC-MS-based methods for multiple analytes or methods of analyzing complex matrices. works in the Quality of Plant Products Team at the Crop Research Institute in Prague as an analytical chemist. She develops and applies analytical methods for the determination of primary and secondary metabolites in various crop matrices. She is mainly interested in the occurrence of Fusarium mycotoxins and is developing analytical methods for their determination and to elucidate genetic aspects of resistance to Fusarium infection. She also investigates the presence of antioxidants in less well-known crops and changes in antioxidant levels during storage and processing. studied Pharmaceutical Sciences at Ghent University, Belgium. During her master’s thesis at IFA-Tulln, she worked on the development of analytical methods for the detection of conjugated mycotoxins. She is particularly interested in the determination of deoxynivalenol and its conjugated forms in cereals. received her PhD degree from the University of Natural Resources and Life Sciences, Vienna (BOKU) in Austria in 2014 and is currently a postdoctoral fellow in the Christian Doppler Laboratory for Mycotoxin Metabolism and the Center for Analytical Chemistry at the Department of Agrobiotechnology (IFA-Tulln) of BOKU. Her research focuses on the development of methods based on liquid chromatography coupled to mass spectrometry for the determination of mycotoxins, their plant metabolites, and other fungal metabolites in food. is Full Professor for (Bio-)Analytics and Organic Trace Analysis and is Head of the IFA-Tulln (where there are more than 180 co-workers) at the University of Natural Resources and Life Sciences, Vienna (BOKU). In 2009/2010 he worked for 1 year as A/Chief of Health Canada’s Food Research Division in Ottawa. He has received 6 scientific awards and is (co-)author of more than 250 SCI publications (h-index: 41). His current research interests are in the areas of plant–fungi metabolomics and novel mass spectrometric methods for the determination of multiple mycotoxins including their conjugation and transformation products in food, feed, and other biological matrices. currently works as a post-doc in the Plant–Pathogen Interaction Group at the Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU). He previously worked as a post-doc in the Christian Doppler Research Laboratory of Innovative Bran Biorefinery (CEREVAL) at BOKU, where he carried out research on industrial food and feed applications of wheat bran. He obtained his doctoral degree in 2012 at the Department of Food Science and Technology (BOKU). His key areas of expertise are mycotoxins, protein production and purification, enzyme kinetics, glycosyl hydrolases, glycosyltransferases, and carbohydrate metabolism of lactic acid bacteria. is Leader of the Plant–Pathogen Interaction Group at the Department of Applied Genetics and Cell Biology of the University of Natural Resources and Life Sciences, Vienna (BOKU). His main research interest is plant genes involved in the metabolization of mycotoxins. His group identified the first UDP-glucosyltransferase genes from Arabidopsis and barley that encode UDP-glucosyltransferases with the ability to convert deoxynivalenol into deoxynivalenol-3-O-glucoside. is Associate Professor at the University of Natural Resources and Life Sciences, Vienna (BOKU) and Head of the Christian Doppler Laboratory for Mycotoxin Metabolism. In 2006 he received the Brigitte Gedek Award from the German Society of Mycotoxin Research for his PhD thesis on masked mycotoxins. He continued his research in the lab of Rudi Krska at the IFA-Tulln, and spent some months abroad at the Danish Technical University and the Food Research Division of Health Canada in Ottawa. An expert in the areas of (modified) mycotoxins and LC-MS, his scientific output includes around 100 SCI publications. A critical assessment of three previously published indirect methods based on acidic hydrolysis using superacids for the determination of “free” and “total” deoxynivalenol (DON) was carried out. The modified mycotoxins DON-3-glucoside (D3G), 3-acetyl-DON (3ADON), and 15-acetyl-DON (15ADON) were chosen as model analytes. The initial experiments focused on the stability/degradation of DON under hydrolytic conditions and the ability to release DON from the modified forms. Acidic conditions that were capable of cleaving D3G, 3ADON, and 15ADON to DON were not found, raising doubts over the efficacy of previously published indirect methods for total DON determination. Validation of these indirect methods for wheat, maize, and barley using UHPLC-MS/MS was performed in order to test the accuracy of the generated results. Validation data for DON, D3G, 3ADON, and 15ADON in nonhydrolyzed and hydrolyzed matrices were obtained. Under the tested conditions, DON was not released from D3G, 3ADON, or 15ADON after hydrolysis and thus none of the published methods were able to cleave the modified forms of DON. In addition to acids, alkaline hydrolysis with KOH for an extended time and at elevated temperatures was also tested. 3ADON and 15ADON were cleaved under the alkaline pH caused by the addition of KOH or aqueous K2CO3 to “neutralize” the acidic sample extracts in the published studies. The published additional DON increase after hydrolysis may have been caused by huge differences in matrix effects and the recovery of DON in nonhydrolyzed and hydrolyzed matrices as well as by the alkaline cleavage of 3ADON or 15ADON after the neutralization of hydrolyzed extracts.
Keywords: Masked mycotoxins; LC-MS/MS; Chemical hydrolysis; Wheat; Barley; Maize
Sensitive gluten determination in gluten-free foods by an electrochemical aptamer-based assay by Sonia Amaya-González; Noemí de-los-Santos-Álvarez; Arturo J. Miranda-Ordieres; María Jesús Lobo-Castañón (6021-6029).
Enzyme immunoassays are currently the methods of choice for gluten control in foods labelled as gluten free, providing a mechanism for assessing food safety for consumption by coeliac and other allergic patients. However, their limitations, many of them associated to the reactivity of the different antibodies used and their degree of specificity, have prevented the establishment of a standardised method of analysis. We explore new methods for quantitatively determining gluten content in foods based on the use of two recently described aptamers, raised against a 33-mer peptide recognised as the immunodominant fragment from α2-gliadin. The assays use the target peptide immobilised onto streptavidin-coated magnetic beads in combination with a limited amount of biotin-aptamer in a competitive format, followed by streptavidin-peroxidase labelling of the aptamer that remains bound to the magnetic beads. The enzyme activity onto the beads, measured by chronoamperometry in disposable screen-printed electrodes, is inversely related to the target concentration in the test solution. We find that while the assay using the aptamer with the highest affinity towards the target (Gli 4) achieves low detection limits (~0.5 ppm) and excellent analytical performance, when challenged in samples containing the intact protein, gliadin, it fails in detecting the peptide in solution. This problem is circumvented by employing another aptamer (Gli 1), the most abundant one in the SELEX pool, as a receptor. The proposed assays allow the convenient detection of the allergen in different kinds of food samples, including heat-treated and hydrolysed ones. The obtained results correlate with those of commercially available antibody-based assays, providing an alternative for ensuring the safety and quality of nominally gluten-free foods. Graphical Abstract Electrochemical magnetoassay for gluten determination using biotin-aptamers as receptors
Keywords: Aptamer; Coeliac disease; Electrochemical detection; Gliadin analysis; Gluten; 33-mer peptide
Silver-nanoparticle-based surface-enhanced Raman scattering wiper for the detection of dye adulteration of medicinal herbs by Dan Li; Qingxia Zhu; Diya Lv; Binxing Zheng; Yanhua Liu; Yifeng Chai; Feng Lu (6031-6039).
By using a silver nanoparticle wiper as a surface-enhanced Raman scattering substrate, a highly sensitive, convenient, and rapid platform for detecting dye adulteration of medicinal herbs was obtained. Commercially available filter paper was functionalized with silver nanoparticles to transform it into the flexible wiper. This device was found to collect dye molecules with unprecedented ease. Experiments were performed to optimize various factors such as the type of wiper used, the wetting reagent, and the wetting/wiping mode and time. Excellent wiper performance was observed in the detection of the simulated adulteration of samples with dyes at various concentrations. The limits of detection for nine dyes, including 10−6 g/mL for malachite green, 10−7 g/mL for Rhodamine 6G, and 5 × 10−8 g/mL for methylene blue, were discerned. The results of this investigation show that this proposed method is potentially highly advantageous for field-based applications. Graphical Abstract Schematic diagram illustrating the fabrication of the paper-based SERS substrate, sample collection process on a herb and SERS examination with the portable Raman spectrometer
Keywords: Surface-enhanced Raman scattering; Silver nanoparticle wiper; Dye adulteration; Medicinal herbs
Monolith immuno-affinity enrichment liquid chromatography tandem mass spectrometry for quantitative protein analysis of recombinant bovine somatotropin in serum by Nathalie G. E. Smits; Marco H. Blokland; Klaas L. Wubs; Merel A. Nessen; Leen A. van Ginkel; Michel W. F. Nielen (6041-6050).
The use of recombinant bovine somatotropin (rbST) to enhance milk production is approved in several countries, but it is prohibited in the European Union. According to EU legislation, it is necessary to confirm positive screening results prior to enforcement. Although adequate screening assays are available nowadays, development of liquid chromatography tandem mass spectrometry (LC-MS/MS) confirmatory methods to detect low levels of rbST is still a challenge. Here, we present a novel approach using immuno-affinity enrichment on monolithic micro-columns in combination with state-of-the-art ultra-high pressure LC-MS/MS (UHPLC-MS/MS) detection. The developed approach enables detection and confirmation of rbST in serum at a decision limit (CCα) concentration of 0.8 ng mL−1. Furthermore, the method is easy to handle, robust and reproducible. We successfully applied the confirmatory method to serum samples from rbST treated cows that were found suspect after immunoassay-based screening. The use of rbST could be confirmed over 1 week after treatment, and the developed method demonstrated the sensitivity needed for effective control. Graphical Abstract Graphical summary of the workflow, for serum preparation, enrichment with monolith microcolumns and LC-MS/MS measurement of rbST
Keywords: Liquid chromatography; Mass spectrometry; Immuno-affinity enrichment; Monolith micro-column; Recombinant bovine somatotropin; bST
Ca2+ concentration-dependent conformational change of FVIII B-domain observed by atomic force microscopy by Klaus Bonazza; Hanspeter Rottensteiner; Gerald Schrenk; Christian Fiedler; Friedrich Scheiflinger; Günter Allmaier; Peter L. Turecek; Gernot Friedbacher (6051-6056).
FVIII is a multi-domain protein organized in a heavy and a light chain, and a B-domain whose biological function is still a matter of debate. The 3D structure of a B-domain-deleted FVIII variant has been determined by X-ray crystallography, leaving unexplained the functional nature of the flexible B-domain which could play an important role in the structure-function relationship since it is removed during the activation process. To obtain clues on the function of the B-domain, the morphology of full-length FVIII and its isolated domains was determined in the absence or presence of Ca2+. Recombinant full-length FVIII, the purified heavy chain, light chain and B-domain as well as B-domain-deleted rFVIII were analysed in buffers of different Ca2+ concentrations by atomic force microscopy. In the absence of Ca2+, FVIII appeared as a globular molecule, whereas at high amounts of Ca2+ up to 50-nm long tail structures emerged. These tails could be identified as unravelled B-domains, as images of isolated B-domains showed the same morphology and heavy chains which include the B-domain were also rich of tails, whereas the isolated light chains and B-domain-deleted FVIII lacked any deviation from a globular shape. The images further suggested that the B-domain interacts with the light chain particularly at low Ca2+ concentrations. Our results show a Ca2+-regulated conformational change of the B-domain in the context of full-length rFVIII. As the B-domain tightly associated with the core of the FVIII molecule under low Ca2+-concentrations, a stabilizing function on FVIII under non-activating conditions may be proposed.
Keywords: Atomic force microscopy; Blood; Factor VIII; Thrombosis; Structure-function relationship; Ca2+ dependence
An integrated strategy for the systematic characterization and discovery of new indole alkaloids from Uncaria rhynchophylla by UHPLC/DAD/LTQ-Orbitrap-MS by Huiqin Pan; Wenzhi Yang; Yibei Zhang; Min Yang; Ruihong Feng; Wanying Wu; Dean Guo (6057-6070).
The exploration of new chemical entities from herbal medicines may provide candidates for the in silico screening of drug leads. However, this significant work is hindered by the presence of multiple classes of plant metabolites and many re-discovered structures. This study presents an integrated strategy that uses ultrahigh-performance liquid chromatography/linear ion-trap quadrupole/Orbitrap mass spectrometry (UHPLC/LTQ-Orbitrap-MS) coupled with in-house library data for the systematic characterization and discovery of new potentially bioactive molecules. Exploration of the indole alkaloids from Uncaria rhynchophylla (UR) is presented as a model study. Initially, the primary characterization of alkaloids was achieved using mass defect filtering and neutral loss filtering. Subsequently, phytochemical isolation obtained 14 alkaloid compounds as reference standards, including a new one identified as 16,17-dihydro-O-demethylhirsuteine by NMR analyses. The direct-infusion fragmentation behaviors of these isolated alkaloids were studied to provide diagnostic structural information facilitating the rapid differentiation and characterization of four different alkaloid subtypes. Ultimately, after combining the experimental results with a survey of an in-house library containing 129 alkaloids isolated from the Uncaria genus, a total of 92 alkaloids (60 free alkaloids and 32 alkaloid O-glycosides) were identified or tentatively characterized, 56 of which are potential new alkaloids for the Uncaria genus. Hydroxylation on ring A, broad variations in the C-15 side chain, new N-oxides, and numerous O-glycosides, represent the novel features of the newly discovered indole alkaloid structures. These results greatly expand our knowledge of UR chemistry and are useful for the computational screening of potentially bioactive molecules from indole alkaloids. Graphical Abstract A four-step integrated strategy for the systematic characterization and efficient discovery of new indole alkaloids from Uncaria rhynchophylla
Keywords: Uncaria rhynchophylla ; UHPLC/LTQ-Orbitrap-MS; New indole alkaloid; Systematic characterization; Mass defect filtering
High-internal-phase-emulsion polymeric monolith coupled with liquid chromatography–electrospray tandem mass spectrometry for enrichment and sensitive detection of trace cytokinins in plant samples by Fuyou Du; Lin Sun; Xian Zhen; Honggang Nie; Yanjie Zheng; Guihua Ruan; Jianping Li (6071-6079).
High-internal-phase-emulsion polymers (polyHIPEs) show great promise as solid-phase-extraction (SPE) materials because of the tremendous porosity and highly interconnected framework afforded by the high-internal-phase-emulsion (HIPE) technique. In this work, polyHIPE monolithic columns as novel SPE materials were prepared and applied to trace enrichment of cytokinins (CKs) from complex plant samples. The polyHIPE monoliths were synthesized via the in-situ polymerization of the continuous phase of a HIPE containing styrene (STY) and divinylbenzene (DVB) in a stainless column, and revealed highly efficient and selective enrichment ability for aromatic compounds. Under the optimized experimental conditions, a method using a monolithic polyHIPE column combined with liquid chromatography–electrospray tandem mass spectrometry (LC–MS–MS) was developed for the simultaneous extraction and sensitive determination of trans-zeatin (tZ), meta-topolin (mT), kinetin (K), and kinetin riboside (KR). The proposed method had good linearity, with correlation coefficients (R 2) from 0.9957 to 0.9984, and low detection limits (LODs, S/N = 3) in the range 2.4–47 pg mL−1 for the four CKs. The method was successfully applied to the determination of CKs in real plant samples, and obtained good recoveries ranging from 68.8 % to 103.0 % and relative standard deviations (RSDs) lower than 16 %.
Keywords: High-internal-phase emulsion; Monolithic column; Solid-phase extraction; Cytokinins; Liquid chromatography–mass spectrometry
Ultrafiltration coupled with high-performance liquid chromatography and quadrupole-time-of-flight mass spectrometry for screening lipase binders from different extracts of Dendrobium officinale by Yi Tao; Hao Cai; Weidong Li; Baochang Cai (6081-6093).
Pancreatic lipase plays essential roles in the digestion, transport, and processing of dietary lipids in humans. Inhibition of pancreatic lipase leading to the decrease of lipid absorption may be used for treating obesity. In the present study, a new approach of ultrafiltration coupled with high-performance liquid chromatography and quadrupole-time-of-flight mass spectrometry was established for rapidly detecting lipase binders from different extracts of medicinal plants. Rutin, a model inhibitor of lipase, was selected to optimize the screening conditions, including ion strength, temperature, pH, and incubation time. Meanwhile, the specificity of the approach was investigated by using denatured lipase and inactive compound emodin. The optimal screening conditions were as follows: ion strength 75 mM, temperature 37 °C, pH 7.4, and incubation time 10 min. Furthermore, linearity, accuracy, precision, and matrix effect of the approach were well validated. Finally, lipase binders were screened from different extracts of Dendrobium officinale by applying the established approach and were subsequently subjected to traditional lipase inhibitory assay. Eleven lipase inhibitors were identified, eight of which, namely naringenine, vicenin II, schaftoside, isoschaftoside, isoquercetrin, kaempferol 3-O-β-d-glucopyranoside, vitexin 2″-O-glucoside, and vitexin 2″-O-rhamnoside, were reported for the first time. In addition, docking experiments were performed to determine the preferred binding sites of these new lipase inhibitors.
Keywords: Lipase; Dendrobium officinale ; Ultrafiltration; Mass spectrometry
Metabolic fingerprinting of Lactobacillus paracasei: a multi-criteria evaluation of methods for extraction of intracellular metabolites by Kristina B. Jäpelt; Nikoline J. Nielsen; Stefanie Wiese; Jan H. Christensen (6095-6104).
An untargeted multi-criteria approach was used to select the best extraction method among freeze-thawing in methanol (FTM), boiling ethanol (BE) and chloroform-methanol (CM) for gas chromatography mass spectrometry (GC-MS) metabolic fingerprinting of Lactobacillus paracasei subsp. paracasei (CRL-431®). The following results were obtained: (i) coverage and efficiency, measured by the number of features extracted and the sum of feature intensities, showed that FTM extraction resulted in the largest compound coverage with a total number of features 8.9 × 103 ± 0.5 × 103, while merely 6.6 × 103 ± 0.9 × 103 and 7.9 × 103 ± 0.8 × 103 were detected in BE or CM, respectively; (ii) the similarity of extraction methods, measured by common features, demonstrated that FTM yielded the most complementary information to BE and CM; i.e. 17 and 33 % of the features of FTM extracted were unique compared to CM and BE, respectively; and (iii) a clear-cut separation according to extraction method was demonstrated by assessment of the metabolic fingerprints by pixel-based data analysis. Indications of metabolite degradation were observed under the elevated temperature for BE extraction. A superior coverage of FTM together with a high repeatability over nearly the whole range of GC-amenable compounds makes this the extraction method of choice for metabolic fingerprinting of L. paracasei.
Keywords: Microbial metabolomics; Pixel-based data analysis; Feature detection and extraction; Gas chromatography; Mass spectrometry
Intraspecific variations in Conus purpurascens injected venom using LC/MALDI-TOF-MS and LC-ESI-TripleTOF-MS by Alena M. Rodriguez; Sebastien Dutertre; Richard J. Lewis; Frank Marí (6105-6116).
The venom of cone snails is composed of highly modified peptides (conopeptides) that target a variety of ion channels and receptors. The venom of these marine gastropods represents a largely untapped resource of bioactive compounds of potential pharmaceutical value. Here, we use a combination of bioanalytical techniques to uncover the extent of venom expression variability in Conus purpurascens, a fish-hunting cone snail species. The injected venom of nine specimens of C. purpurascens was separated by reversed-phase high-performance liquid chromatography (RP-HPLC), and fractions were analyzed using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) in parallel with liquid chromatography-electrospray ionization (LC-ESI)-TripleTOF-MS to compare standard analytical protocols used in preparative bioassay-guided fractionations with a deeper peptidomic analysis. Here, we show that C. purpurascens exhibits pronounced intraspecific venom variability. RP-HPLC fractionation followed by MALDI-TOF-MS analysis of the injected venom of these nine specimens identified 463 distinct masses, with none common to all specimens. Using LC-ESI-TripleTOF-MS, the injected venom of these nine specimens yielded a total of 5517 unique masses. We also compare the injected venom of two specimens with their corresponding dissected venom. We found 2566 and 1990 unique masses for the dissected venom compared to 941 and 1959 masses in their corresponding injected venom. Of these, 742 and 1004 masses overlapped between the dissected and injected venom, respectively. The results indicate that larger conopeptide libraries can be assessed by studying multiple individuals of a given cone snail species. This expanded library of conopeptides enhances the opportunities for discovery of molecular modulators with direct relevance to human therapeutics. Graphical Abstract The venom of cone snails are extraordinarily complex mixtures of highly modified peptides. Venom analysis requires separation through RP-HPLC followed by MALDI-TOF mass spectrometry or direct analysis using LC-ESI-TripleTOF-MS. Using these techniques, venom intraspecific variability and comparison between injected and dissected were assessed
Keywords: Conotoxin; Conopeptide; Cone snail; Liquid chromatography; Mass spectrometry; Peptidomics
Novel chemiluminescent imaging microtiter plates for high-throughput detection of multiple serum biomarkers related to Down’s syndrome via soybean peroxidase as label enzyme by Fang Zhao; Da Chai; Jusheng Lu; Jiachao Yu; Songqin Liu (6117-6126).
Novel chemiluminescent (CL) imaging microtiter plates with high-throughput, low-cost, and simple operation for detection of four biomarkers related to Down’s syndrome screening were developed and evaluated. To enhance the sensitivity of CL immunosensing, soybean peroxidase (SBP) was used instead of horseradish peroxide (HRP) as a label enzyme. The microtiter plates were fabricated by simultaneously immobilizing four capture monoclonal antibodies, anti-inhibin-A, anti-unconjugated oestriol (anti-uE3), anti-alpha-fetoprotein (anti-AFP), and beta anti-HCG (anti-β-HCG), on nitrocellulose (NC) membrane to form immunosensing microtiter wells. Under a sandwiched immunoassay, the CL signals on each sensing site of the microtiter plates were collected by a charge-coupled device (CCD), presenting an array-based chemiluminescence imaging method for detection of four target antigens in a well at the same time. The linear response to the analyte concentration ranged from 0.1 to 40 ng/mL for inhibin-A, 0.075 to 40 ng/mL for uE3, 0.2 to 400 ng/mL for AFP, and 0.4 to 220 ng/mL for β-HCG. The proposed microtiter plates possessed high-throughput, good stability, and acceptable accuracy for detection of four antigens in clinical serum samples and demonstrated potential for practical applicability of the proposed method to Down’s syndrome screening. Graphical Abstract Schematic evaluation of the microtiter plater for simultaneous detection of the four biomarkers
Keywords: Soybean peroxidase; High throughput; Chemiluminescence; Down’s syndrome screening; Microtiter plates
Imidazolium-based ionic liquid derivative/CuII complexes as efficient catalysts of the lucigenin chemiluminescence system and its application to H2O2 and glucose detection by Tahereh Khajvand; Olia Alijanpour; Mohammad Javad Chaichi; Majid Vafaeezadeh; Mohammad Mahmoodi Hashemi (6127-6136).
The effects of six synthetic imidazolium-based ionic liquids (ILs) on the CuII-catalyzed chemiluminescence of lucigenin (Luc-CL) in the pH range 6.0–11 were investigated. Preliminary experiments found that the CL emission was strongly enhanced or inhibited in the presence of the ILs. The degree of enhancement or inhibition of the CL intensity in the presence of each IL was related to the molecular structure of the IL, the medium used, and the pH. The maximum enhancement of the CL intensity was observed at pH 9.0 (amplification factor = 443). This decrease in the pH at which maximum CL enhancement occurred and the substantial signal amplification of the Luc-CL may be related to a strong interaction between CuII and the imidazolium ring of superior ILs at this pH. Additionally, the formation of IL microdomains in semi-aqueous media permitted more solubility of the product yielded by the Luc-CL reaction (N-methylacridone), which could increase the CL intensity. To obtain consistent data on the catalytic efficiency of CuII in the presence of various ILs as well as the corresponding CL emission intensities, fluorescence quantum yields (Φ F) of lucigenin were measured under the same conditions. Comparison of the data pointed to the mechanism that controls the properties of Luc-CL in the presence of the CuII/IL complexes. Based on the catalytic effect of the CuII/IL complex and the measurement of the enzymatically generated H2O2, a novel, simple, and sensitive CL method for determining glucose with a detection limit (LoD) of 6.5 μM was developed. Moreover, this method was satisfactorily applied to the determination of glucose in human serum and urine samples. Graphical Abstract The lucigenin chemiluminescence assay for H2O2 and glucose using imidazolium–based ionic liquid derivatives/CuII complexes as efficient catalysts at pH 9.0
Keywords: Lucigenin chemiluminescence; Ionic liquids; Fluorescence quantum yield; H2O2 ; Glucose
A novel two-dimensional liquid-chromatography method for online prediction of the toxicity of transformation products of benzophenones after water chlorination by Jian Li; Li-yun Ma; Li Xu; Zhi-guo Shi (6137-6148).
Benzophenone-type UV filters (BPs) are ubiquitous in the environment. Transformation products (TPs) of BPs with suspected toxicity are likely to be produced during disinfection of water by chlorination. To quickly predict the toxicity of TPs, in this study, a novel two-dimensional liquid-chromatography (2D-LC) method was established in which the objective of the first dimension was to separate the multiple components of the BPs sample after chlorination, using a reversed-phase liquid-chromatography mode. A biochromatographic system, i.e. bio-partitioning micellar chromatography with the polyoxyethylene (23) lauryl ether aqueous solution as the mobile phase, served as the second dimension to predict the toxicity of the fraction from the first dimension on the basis of the quantitative retention–activity relationships (QRARs) model. Six BPs, namely 2,4-dihydroxybenzophenone, oxybenzone, 4-hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone, were the target analytes subjected to chlorination. The products of these BPs after chlorination were directly injected to the 2D-LC system for analysis. The results indicated that most TPs may be less toxic than their parent chemicals, but some may be more toxic, and that intestinal toxicity of TPs may be more obvious than blood toxicity. The proposed method is time-saving, high-throughput, and reliable, and has great potential for predicting toxicity or bioactivity of unknown and/or known components in a complex sample. Graphical Abstract The scheme for the 2D-LC online prediction of toxicity of the transformation products of benzophenone-type UV filters after chlorination
Keywords: Benzophenones; Chlorination; Two-dimensional liquid chromatography; Toxicity simulation; Biochromatography
Optimization of ultrasonic-assisted extraction for determination of polycyclic aromatic hydrocarbons in biochar-based fertilizer by gas chromatography–mass spectrometry by Ping Chen; Mingxing Sun; Zhixiu Zhu; Jidong Zhang; Guoqing Shen (6149-6157).
Application of biochar-based fertilizers is increasingly being considered for its potential agronomic and environmental benefits. However, biochar may contain residues of polycyclic aromatic hydrocarbons (PAHs) as a result of its production by pyrolysis. The strong adsorption of PAHs to biochar makes extraction and analysis of biochar-based fertilizers difficult. This study optimizes the extraction of PAHs in biochar-based fertilizer samples by using an ultrasonic bath for quantification by gas chromatography–mass spectrometry. Among 12 solvents, acetone–cyclohexane (1:1) mixture was selected as the optimum solvent for extraction. Three variables affecting the extraction were studied by Box–Behnken design. The optimum conditions were 57 °C extraction temperature, 81 min extraction time, and two extraction cycles, which were validated by assessing the linearity of analysis, LOD, LOQ, recovery, and levels of PAHs in real biochar-based fertilizer samples. Results revealed that the 16 U.S. EPA PAHs had good linearity, with squared correlation coefficients greater than 0.99. LODs were low, ranging from 2.2 ng g−1 (acenaphthene) to 23.55 ng g−1 (indeno[1,2,3-cd]perylene), and LOQs varied from 7.51 ng g−1 to 78.49 ng g−1. The recoveries of 16 individual PAHs from the three biochar-based fertilizer samples were 81.8–109.4 %. Graphical Abstract Use of RSM to optimize UAE for extraction of the PAHs in biochar-based fertilizer
Keywords: Biochar; Fertilizer; Ultrasonic-assisted extraction; Polycyclic aromatic hydrocarbons; Response surface method
Time-of-flight accurate mass spectrometry identification of quinoline alkaloids in honey by Tamara Rodríguez-Cabo; Mohammed Moniruzzaman; Isaac Rodríguez; María Ramil; Rafael Cela; Siew Hua Gan (6159-6170).
Time-of-flight accurate mass spectrometry (TOF-MS), following a previous chromatographic (gas or liquid chromatography) separation step, is applied to the identification and structural elucidation of quinoline-like alkaloids in honey. Both electron ionization (EI) MS and positive electrospray (ESI+) MS spectra afforded the molecular ions (M.+ and M+H+, respectively) of target compounds with mass errors below 5 mDa. Scan EI-MS and product ion scan ESI-MS/MS spectra permitted confirmation of the existence of a quinoline ring in the structures of the candidate compounds. Also, the observed fragmentation patterns were useful to discriminate between quinoline derivatives having the same empirical formula but different functionalities, such as aldoximes and amides. In the particular case of phenylquinolines, ESI-MS/MS spectra provided valuable clues regarding the position of the phenyl moiety attached to the quinoline ring. The aforementioned spectral information, combined with retention times matching, led to the identification of quinoline and five quinoline derivatives, substituted at carbon number 4, in honey samples. An isomer of phenyquinoline was also noticed; however, its exact structure could not be established. Liquid–liquid microextraction and gas chromatography (GC) TOF-MS were applied to the screening of the aforementioned compounds in a total of 62 honeys. Species displaying higher occurrence frequencies were 4-quinolinecarbonitrile, 4-quinolinecarboxaldehyde, 4-quinolinealdoxime, and the phenylquinoline isomer. The Pearson test revealed strong correlations among the first three compounds.
Keywords: Quinoline; Alkaloids; Honey; Time-of-flight mass spectrometry
New approach to the determination of contaminants of emerging concern in natural water: study of alprazolam employing adsorptive cathodic stripping voltammetry by Chalder Nogueira Nunes; Lucas Ely Pauluk; Vanessa Egéa dos Anjos; Mauro Chierici Lopes; Sueli Pércio Quináia (6171-6179).
Contaminants of emerging concern (CECs) are chemicals, including pharmaceutical and personal care products, not commonly monitored in the aquatic environment. Pharmaceuticals are nowadays considered as an important environmental contaminant. Chromatography methods which require expensive equipment and complicated sample pretreatment are used for detection of CECs in natural water. Thus, in this study we proposed a simple, fast, and low-cost voltammetric method as a screening tool for the determination of CECs in natural water prior to chromatography. A case study was conducted with alprazolam (benzodiazepine). The method was optimized and validated in-house. The limit of quantification was 0.4 μg L−1 for a 120 s preconcentration time. The recoveries ranged from 93 to 120 % for accuracy tests. A further proposal aim was to determine for the first time the occurrence of alprazolam in Brazilian river water and to evaluate its potential use as a marker of contamination by wastewater.
Keywords: Alprazolam; Natural water; Benzodiazepine; Voltammetry; Validation
A cationic cysteine-hydrazide as an enrichment tool for the mass spectrometric characterization of bacterial free oligosaccharides by Kyoung-Soon Jang; Roger R. Nani; Anastasia Kalli; Sergiy Levin; Axel Müller; Sonja Hess; Sarah E. Reisman; William M. Clemons Jr. (6181-6190).
In Campylobacterales and related ε-proteobacteria with N-linked glycosylation (NLG) pathways, free oligosaccharides (fOS) are released into the periplasmic space from lipid-linked precursors by the bacterial oligosaccharyltransferase (PglB). This hydrolysis results in the same molecular structure as the oligosaccharide that is transferred to a protein to be glycosylated. This allowed for the general elucidation of the fOS-branched structures and monosaccharides from a number of species using standard enrichment and mass spectrometry methods. To aid characterization of fOS, hydrazide chemistry has often been used for chemical modification of the reducing part of oligosaccharides resulting in better selectivity and sensitivity in mass spectrometry; however, the removal of the unreacted reagents used for the modification often causes the loss of the sample. Here, we develop a more robust method for fOS purification and characterize glycostructures using complementary tandem mass spectrometry (MS/MS) analysis. A cationic cysteine hydrazide derivative was synthesized to selectively isolate fOS from periplasmic fractions of bacteria. The cysteine hydrazide nicotinamide (Cyhn) probe possesses both thiol and cationic moieties. The former enables reversible conjugation to a thiol-activated solid support, while the latter improves the ionization signal during MS analysis. This enrichment was validated on the well-studied Campylobacter jejuni by identifying fOS from the periplasmic extracts. Using complementary MS/MS analysis, we approximated data of a known structure of the fOS from Campylobacter concisus. This versatile enrichment technique allows for the exploration of a diversity of protein glycosylation pathways.
Keywords: Enrichment; Free oligosaccharide; Campylobacter; Hydrazide; Glycomics
Possibilities and limitations of signal summing for an immunosuppressant LC-MS/MS method by Steven Pauwels; Ivo Jans; Nele Peersman; Jaak Billen; Dirk Vanderschueren; Koen Desmet; Pieter Vermeersch (6191-6199).
Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the method of choice for quantifying small molecules in research and clinical setting. Although there is a large toolkit to increase quantification levels for LC-MS/MS, these techniques are sometimes insufficient to attain the needed limits of quantification (LOQs) or the method becomes too impractical for routine use. We examined the possibilities and limitations of signal summing, an under-utilized, easy-to-apply practice to increase LOQs for an immunosuppressant LC-MS/MS method. The limits of signal summing for everolimus were tested by running samples of everolimus at three concentrations in triplicate programming, increasing amounts of identical transitions in a constant cycle time up to the maximum number the software permitted to sum. The increase in peak area and the signal-to-noise ratio were determined. The effect on imprecision of peak areas and response ratios was evaluated by injection of a low concentration of everolimus tenfold using respectively one and five identical transitions, retaining an identical ion counting time. We compared the imprecision, LOQ, and recovery for our routine everolimus method (using one transition for everolimus and one for d3-everolimus) and an adapted method summing three identical transitions for everolimus (and one for d3-everolimus). The increase in signal was close to the theoretically expected one with a larger experimental spread for everolimus once more than five transitions were used. There was no clear beneficial effect of summing on imprecision. The adapted everolimus method showed a lower LOQ, but comparable imprecision and recovery as the routine method. Quantification levels can be improved by signal summing. No clear effect on imprecision was observed.
Keywords: Signal summing; Liquid chromatography; Mass spectrometry; Sensitivity; Immunosuppressant; Estradiol
Chiral separation of d/l-aldoses by micellar electrokinetic chromatography using a chiral derivatization reagent and a phenylboronic acid complex by Sachio Yamamoto; Yoko Tamata; Kaori Sejima; Mitsuhiro Kinoshita; Shigeo Suzuki (6201-6206).
A novel method was developed for d/l-isomeric separation of aldopentoses and aldohexoses as their (S)-(+)-4-(N,N-dimethylaminosulfonyl)-7-(3-aminopyrrolidin-1-yl)-2,1,3-benzoxadiazole derivatives using phenylboronate buffer containing sodium dodecyl sulfate as a background electrolyte. The combination of derivatization with a chiral labeling reagent and micellar electrokinetic chromatography with phenylboronate made possible the efficient separation of d/l isomers as well as epimeric isomers of aldopentoses and aldohexoses. Laser-induced fluorescence detection permitted the micromolar-level determination of monosaccharide derivatives. The limit of detection was 105 amol (300 nM), and the repeatabilities of the migration times and peak area responses were 0.8 % and 7.9 % (relative standard deviation; n = 6), respectively. The method was applied to the determination of d/l- galactose in red seaweed.
Keywords: Chiral separation; d/l-Aldose separation; Micellar electrokinetic chromatography; Phenylboronic acid complex; (S)-(+)-4-(N,N-Dimethylaminosulfonyl)-7-(3-aminopyrrolidin-1-yl)-2,1,3-benzoxadiazole
“One-shot” analysis of PDE-5 inhibitors and analogues in counterfeit herbal natural products using an LC-DAD-QTOF system by Claudio Bortolini; Antonio Pivato; Sara Bogialli; Paolo Pastore (6207-6216).
A highly selective and robust method for simultaneous screening and confirmation of target and non-target phosphodiesterase type 5 (PDE-5) inhibitor analogues within a single chromatographic run in counterfeit herbal products was developed. The protocol, based on an easy and rapid extraction with a water/acetonitrile 1 % formic acid solution, followed by sonication and centrifugation, exploits an LC-diode array detector-quadrupole-time-of-flight (DAD-QTOF) system. The extraction method was optimized both at high concentrations and at trace levels. These two situations are typically encountered in pharmaceutical formulations and herbal food supplements. Carryover effects, never reported before and occurring mainly for vardenafil, were overcome using a polymer-based column. An in-house validation was carried out using five blanks of different bulk matrices spiked with seven standard analytes, namely yohimbine, sildenafil, vardenafil, tadalafil, homosildenafil, pseudovardenafil and hydroxyhomovardenafil. Reliable quantitation was possible using a conventional standard solution for all the pharmaceutical and herbal samples considered, as matrix effects were eliminated. Accuracy ranged from 80.9 to 108.1 % with overall relative standard deviation (RSD) <11 % (N = 15), measured at 1.0, 5.0 and 10.0 μg/g. Limits of detection (LODs) obtained ensured the determination of cross contaminations at nanogram per gram levels. A database with 82 PDE-5 inhibitor analogues was implemented for automatic non-target analysis. Among the 26 samples of dietary supplements and herbal remedies bulk marketed for erectile dysfunctions, three samples were found to be contaminated with both registered and unregistered synthetic PDE-5 inhibitors, i.e. yohimbine, sildenafil, dimethylsildenafil and thiodimethylsildenafil or thiomethisosildenafil. The occurrence of such contaminations, both at trace levels and at pharmaceutical dosage, indicates the illicit use of synthetic PDE-5 analogues. Graphical Abstract Examples of pharmaceutical formulations and herbal natural products marketed for the erectile dysfunction
Keywords: Natural herbal product; PDE-5 inhibitors; Dietary supplement; Liquid chromatography-high resolution mass spectrometry
Silica-based 2-(N,N-dimethylamino)-1,3-propanediol hydrophilic interaction liquid chromatography stationary phase for separating cephalosporins and carbapenems by Wei Yin; Lingping Cheng; Huihui Chai; Ruiqiang Guo; Renhua Liu; Changhu Chu; John A. Palasota; Xiaohui Cai (6217-6220).
A silica-based stationary phase bearing both hydrophilic hydroxyl and amino groups was developed by covalently bonding a small molecular N,N-dimethylamino 1,3-propanediol moiety onto silica beads via copper(I)-catalyzed Huisgen azide–alkyne 1,3-dipolar cycloaddition (CuAAC). This new stationary phase showed good HILIC characteristics and high column efficiency (the theoretical plate number is up to 37000 plates m−1 in the case of inosine) in the separation of polar compounds, such as nucleosides and bases, organic acids, cephalosporins, and carbapenems.
Keywords: Click 2-(N,N-dimethylamino)-1,3-propanediol; Stationary phase; HILIC; Nucleosides and bases; Cephalosporins and carbapenems
Capillary electrophoresis with mass spectrometric detection for separation of S-nitrosoglutathione and its decomposition products: a deeper insight into the decomposition pathways by Abdulghani Ismail; Fanny d’Orlyé; Sophie Griveau; José Alberto Fracassi da Silva; Fethi Bedioui; Anne Varenne (6221-6226).
S-Nitrosoglutathione (GSNO) is a very important biomolecule that has crucial functions in many physiological and physiopathological processes. GSNO acts as NO donor and is a candidate for future medicines. This work describes, for the first time, the separation and the detection of GSNO and its decomposition products using capillary electrophoresis coupled to mass spectrometry (CE–MS). The separation was performed in slightly alkaline medium (pH 8.5) under positive-ionization MS detection. The identification of three byproducts of GSNO was formally performed for the first time: oxidized glutathione (GSSG), glutathione sulfinic acid (GSO2H), and glutathione sulfonic acid (GSO3H). GSO2H and GSO3H are known to have important biological activity, including inhibition of the glutathione transferase family of enzymes which are responsible for the elimination of many mutagenic, carcinogenic, and pharmacologically active molecules. We observed, after the ageing of GSNO in the solid state, that the proportion of both GSSG and GSO3H increases whereas that of GSO2H decreases. These results enabled us to propose an oxidation scheme explaining the formation of such products.
Keywords: Capillary-electrophoresis mass spectrometry; S-nitrosoglutathione; GSO2H; GSO3H; Decomposition; Oxidation; Reactive nitrogen species