Analytical and Bioanalytical Chemistry (v.409, #15)
Nanofluids and chemical highly retentive hydrogels for controlled and selective removal of overpaintings and undesired graffiti from street art by Rodorico Giorgi; Michele Baglioni; Piero Baglioni (3707-3712).
, PhD in Science for Cultural Heritage Conservation at the University of Florence and BS in Chemistry, is currently an associate professor of Chemistry at the University of Florence and CSGI. Giorgi’s background is in colloids science. His main research interests are the development of methodologies for the conservation of cultural heritage materials such as wall and easel paintings, stone, paper, and archeological wood. Giorgi is the author of about 100 publications in the field of science for conservation. got his PhD in Science for Conservation of Cultural Heritage in 2010. He is currently a post-doctoral research fellow at the CSGI and Chemistry Department, University of Florence. His interests and expertise are related to the development and characterization of soft-matter systems for the cleaning of works of art, such as nanostructured fluids (i.e., microemulsions and micelles) and gels. has been the Chair of Physical Chemistry in the Department of Chemistry at the University of Florence since 1994 and is an MIT affiliate. He was appointed as visiting scientist/professor by the Department of Chemistry of the University of Houston, the Weizmann Institute, the Collège de France, and MIT. He is the Director of the National Center for Colloids and Nanosciences (CSGI), and he is on the advisory boards of several international journals and a member of the scientific board of several national and international institutions and societies. He is the author of more than 350 publications in books and largely diffused international journals. He is also the author of 21 patents. In the field of conservation, he is a pioneer in the application of colloids and soft matter to the conservation of cultural heritage. He has produced several innovative methods for the consolidation and cleaning of paintings and the deacidification of historical documents. One of the main problems connected to the conservation of street art is the selective removal of overlying undesired graffiti, i.e., drawings and tags. Unfortunately, selective and controlled removal of graffiti and overpaintings from street art is almost unachievable using traditional methodologies. Recently, the use of nanofluids confined in highly retentive pHEMA/PVP semi-interpenetrated polymer networks was proposed. Here, we report on the selective removal of acrylic overpaintings from a layer of acrylic paint on mortar mockups in laboratory tests. The results of the cleaning tests were characterized by visual and photographic observation, optical microscopy, and FT-IR microreflectance investigation. It was shown that this methodology represents a major advancement with respect to the use of nonconfined neat solvents.
Keywords: Graffiti; Overpaintings; Selective removal; Street art; Chemical gels; Nanofluids
Implementation of data-dependent isotopologue fragmentation in 13C-based metabolic flux analysis by Teresa Mairinger; Stephan Hann (3713-3718).
A novel analytical approach based on liquid chromatography coupled to quadrupole time of flight mass spectrometry, employing data-dependent triggering for analysis of isotopologue and tandem mass isotopomer fractions of metabolites of the primary carbon metabolism was developed. The implemented QTOFMS method employs automated MS/MS triggering of higher abundant, biologically relevant isotopologues for generating positional information of the respective metabolite. Using this advanced isotopologue selective fragmentation approach enables the generation of significant tandem mass isotopomer data within a short cycle time without compromising sensitivity. Due to a lack of suitable reference material certified for isotopologue ratios, a Pichia pastoris cell extract with a defined 13C distribution as well as a cell extract from a 13C-based metabolic flux experiment were employed for proof of concept. Moreover, a method inter-comparison with an already established GC-CI-(Q)TOFMS approach was conducted. Both methods showed good agreement on isotopologue and tandem mass isotopomer distributions for the two different cell extracts. Graphical abstract Schematic overview of data-dependent isotopologue fragmentation for acquisition of isotopologue and tandem mass isotopomer fractions
Keywords: 13C-based metabolic flux analysis; Isotopologue ratio; Data-dependent fragmentation
Identification of odorants in wood of Calocedrus decurrens (Torr.) Florin by aroma extract dilution analysis and two-dimensional gas chromatography–mass spectrometry/olfactometry by Linda Schreiner; Helene M. Loos; Andrea Buettner (3719-3729).
Food chemist, is a PhD student at the Fraunhofer Institute for Process Engineering and Packaging IVV in collaboration with Friedrich-Alexander-Universität Erlangen-Nürnberg. She works in the field of sensory analytics, focusing on the elucidation of the odor of wood and wood-based products and on possible physiological effects of odorous emissions from nonfood products on humans. is a research associate in the Department of Sensory Analytics at the Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany. Her research interests are the identification of odorants from biological matrices and the impact of odors on human behavior. aroma and smell researcher, was appointed as Full Professor in 2007 and still holds two concurrent positions, as founder and Head of the Department of Sensory Analytics at the Fraunhofer Institute for Process Engineering and Packaging IVV in Freising, Germany, and as a professor and Head of the Odor and Aroma Research Group at Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany. Her expertise encompasses the characterization of the main chemosensory triggers in aromas, flavors, and common odors, based on combined chemoanalytical and human-sensory characterization of the molecular constituents. In view of physiological processes related to odorant exposure and uptake, recent investigations have targeted pharmacokinetic aspects of odorant inhalation, absorption, biotransformation, and elimination from the human body. General emissions of volatile organic compounds from wood are well investigated, but only limited information is available on the odor-active substances contained therein. To close this gap, we aimed at specifically elucidating the odorous constituents of wood from incense cedar [Calocedrus decurrens (Torr.) Florin]; this material is commonly used for the production of a range of products such as pencils and interior accessories. Targeted odorant analysis requires specialized techniques combining modern odorant analytical tools with human-sensory evaluation. Following this concept, the odor profile of the wood sample was first evaluated by human-sensory analyses. Then, the most potent wood odorants were characterized by means of gas chromatography–olfactometry and ranked according to their odor potency via aroma extract dilution analysis. With use of this approach, more than 60 odorous substances were detected, and the 22 most potent odorants were successfully identified by gas chromatography–mass spectrometry/olfactometry and two-dimensional gas chromatography–mass spectrometry/olfactometry. Among the main odorants found were a series of terpenes, several degradation products of fatty acids, and a number of odorants with a phenolic core moiety. Five odorants are reported here for the first time as wood odorants, such as γ-octalactone and 3-phenylpropanoic acid; thymoquinone was demonstrated for the first time to have a pencil-like odor quality.
Keywords: Aroma extract dilution analysis; Gas chromatography–olfactometry; Incense cedar; 2-Isopropyl-5-methyl-1,4-benzoquinone; Thymoquinone; Octalactone
Characterization of IgG glycosylation in rheumatoid arthritis patients by MALDI-TOF-MSn and capillary electrophoresis by Chuncui Huang; Yaming Liu; Hongmei Wu; Dehui Sun; Yan Li (3731-3739).
An analytical method based on the combination of multistage mass spectrometry (MSn) and capillary electrophoresis (CE) was developed for the analysis of immunoglobulin G (IgG) glycosylation in rheumatoid arthritis (RA) patients. It has been recently suggested that IgG glycosylation defect may be involved in RA immunopathogenesis. Complete characterization of glycans, including both qualitative and quantitative analysis, requires a combination of different techniques, and accurate, robust, sensitive, and high-throughput methodologies are important for analysis of clinical samples. In the present study, N-glycosylation of IgG in RA patients and in healthy people was characterized through identification of the released glycans using multistage matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MSn), and quantitation by CE. Assignment of the IgG N-glycan structures was made through branching pattern analysis by MSn with high-throughput. Further accurate quantitation indicated that galactosylation and sialylation of IgG N-glycans in RA cases were significantly lower than in healthy subjects. The results indicate that CE coupled with MSn can identify abnormal glycosylation of IgG in RA patients compared with healthy people, and that the present work is useful for RA mechanism studies and RA diagnosis. Graphical Abstract Qualitative and quantitative analysis of IgG glycosylation in rheumatoid arthritis patients by MALDI-TOF-MSn and capillary electrophoresis
Keywords: Characterization; Glycosylation; Rheumatoid arthritis; MALDI-TOF-MSn ; Capillary electrophoresis
Molecularly imprinted polymer prepared with polyhedral oligomeric silsesquioxane through reversible addition–fragmentation chain transfer polymerization by Shu-Ping Gao; Xue Zhang; Li-Shun Zhang; Yan-Ping Huang; Zhao-Sheng Liu (3741-3748).
Polyhedral oligomeric silsesquioxane (POSS) was utilized to prepare imprinted polymer through reversible addition–fragmentation chain transfer polymerization (RAFT) successfully. The imprinted polymer was made with a mixture of RAFT agent, 4-vinylpyridine (4-VP), POSS monomer [PSS-(1-propylmethacrylate)-heptaisobutyl substituted, MA 0702], and ethylene glycol dimethacrylate (EDMA), with ketoprofen (KET) as template. The influence of polymerization variables, the amount of RAFT agent and POSS monomer, the ratio of KET to 4-VP, and the ratio of 4-VP to EDMA, were investigated on the retention factor and imprinting effect. The greatest imprinting factor of the RAFT agent-based POSS MIP was 15.2, about 1.5 times higher than the RAFT agent-free agent POSS MIP. The permeability, surface morphology, as well as pore size distribution of POSS MIP monoliths made with RAFT agent and without RAFT agent were also studied. The optimal MIP was applied to solid phase extraction for KET from commercial tablets. The mean recoveries of KET for RAFT-based POSS MIP was 85.2% with a relative standard deviation of 2.6%.
Keywords: Molecularly imprinted polymers; Polyhedral oligomeric silsesquioxane; Reversible addition–fragmentation chain transfer polymerization; Molecular recognition; Ketoprofen
Simple and cost-effective liquid chromatography-mass spectrometry method to measure dabrafenib quantitatively and six metabolites semi-quantitatively in human plasma by Svante Vikingsson; Jan-Olof Dahlberg; Johan Hansson; Veronica Höiom; Henrik Gréen (3749-3756).
Dabrafenib is an inhibitor of BRAF V600E used for treating metastatic melanoma but a majority of patients experience adverse effects. Methods to measure the levels of dabrafenib and major metabolites during treatment are needed to allow development of individualized dosing strategies to reduce the burden of such adverse events. In this study, an LC-MS/MS method capable of measuring dabrafenib quantitatively and six metabolites semi-quantitatively is presented. The method is fully validated with regard to dabrafenib in human plasma in the range 5–5000 ng/mL. The analytes were separated on a C18 column after protein precipitation and detected in positive electrospray ionization mode using a Xevo TQ triple quadrupole mass spectrometer. As no commercial reference standards are available, the calibration curve of dabrafenib was used for semi-quantification of dabrafenib metabolites. Compared to earlier methods the presented method represents a simpler and more cost-effective approach suitable for clinical studies. Graphical abstract Combined multi reaction monitoring transitions of dabrafenib and metabolites in a typical case sample.
Keywords: Bioanalytical methods; Biological samples; Drug monitoring/drug screening; HPLC; Mass spectrometry/ICP-MS
Simultaneous determination of multiclass pesticide residues in human plasma using a mini QuEChERS method by Anshuman Srivastava; Satyajeet Rai; Ashish Kumar Sonker; Kajal Karsauliya; Chandra Prabha Pandey; Sheelendra Pratap Singh (3757-3765).
Blood is one of the most assessable matrices for the determination of pesticide residue exposure in humans. Effective sample preparation/cleanup of biological samples is very important in the development of a sensitive, reproducible, and robust method. In the present study, a simple, cost-effective, and rapid gas chromatography–tandem mass spectrometry method has been developed and validated for simultaneous analysis of 31 multiclass (organophosphates, organochlorines, and synthetic pyrethroids) pesticide residues in human plasma by means of a mini QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. We have adopted a modified version of the QuEChERS method, which is primarily used for pesticide residue analysis in food commodities. The QuEChERS method was optimized by use of different extraction solvents and different amounts and combinations of salts and sorbents (primary–secondary amines and C18) for the dispersive solid-phase extraction step. The results show that a combination of ethyl acetate with 2% acetic acid, magnesium sulfate (0.4 g), and solid-phase extraction for sample cleanup with primary–secondary amines (50 mg) per 1-mL volume of plasma is the most suitable for generating acceptable results with high recoveries for all multiclass pesticides from human plasma. The mean recovery ranged from 74% to 109% for all the analytes. The limit of quantification and limit of detection of the method ranged from 0.12 to 13.53 ng mL-1 and from 0.04 to 4.10 ng mL-1 respectively. The intraday precision and the interday precision of the method were 6% or less and 11% or less respectively. This method would be useful for the analysis of a wide range of pesticides of interest in a small volume of clinical and/or forensic samples to support biomonitoring and toxicological applications. Graphical Abstract Pesticide residues analysis in human plasma using mini QuEChERS method
Keywords: Quick, easy, cheap, effective, rugged, and safe; Human plasma; Pesticide residue; Gas chromatography–tandem mass spectrometry; Sample cleanup
A direct label-free MALDI-TOF mass spectrometry based assay for the characterization of inhibitors of protein lysine methyltransferases by Karine Guitot; Thierry Drujon; Fabienne Burlina; Sandrine Sagan; Sandra Beaupierre; Olivier Pamlard; Robert H. Dodd; Catherine Guillou; Gérard Bolbach; Emmanuelle Sachon; Dominique Guianvarc’h (3767-3777).
Histone lysine methylation is associated with essential biological functions like transcription activation or repression, depending on the position and the degree of methylation. This post-translational modification is introduced by protein lysine methyltransferases (KMTs) which catalyze the transfer of one to three methyl groups from the methyl donor S-adenosyl-l-methionine (AdoMet) to the amino group on the side chain of lysines. The regulation of protein lysine methylation plays a primary role not only in the basic functioning of normal cells but also in various pathologies and KMT deregulation is associated with diseases including cancer. These enzymes are therefore attractive targets for the development of new antitumor agents, and there is still a need for direct methodology to screen, identify, and characterize KMT inhibitors. We report here a simple and robust in vitro assay to quantify the enzymatic methylation of KMT by MALDI-TOF mass spectrometry. Following this protocol, we can monitor the methylation events over time on a peptide substrate. We detect in the same spectrum the modified and unmodified substrates, and the ratios of both signals are used to quantify the amount of methylated substrate. We first demonstrated the validity of the assay by determining inhibition parameters of two known inhibitors of the KMT SET7/9 ((R)-PFI-2 and sinefungin). Next, based on structural comparison with these inhibitors, we selected 42 compounds from a chemical library. We applied the MALDI-TOF assay to screen their activity as inhibitors of the KMT SET7/9. This study allowed us to determine inhibition constants as well as kinetic parameters of a series of SET7/9 inhibitors and to initiate a structure activity discussion with this family of compounds. This assay is versatile and can be easily adapted to other KMT substrates and enzymes as well as automatized.
Keywords: Protein lysine methyltransferase; H3K4 methylation; Enzymatic assay; MALDI-TOF MS; Inhibitor characterization; (R)-PFI-2
Pioneering particle-based strategy for isolating viable bacteria from multipart soil samples compatible with Raman spectroscopy by Martha Schwarz; Sandra Kloß; Stephan Stöckel; Sibyll Pollok; Andreas Holländer; Dana Cialla-May; Karina Weber; Jürgen Popp (3779-3788).
The study of edaphic bacteria is of great interest, particularly for evaluating soil remediation and recultivation methods. Therefore, a fast and simple strategy to isolate various bacteria from complex soil samples using poly(ethyleneimine) (PEI)-modified polyethylene particles is introduced. The research focuses on the binding behavior under different conditions, such as the composition, pH value, and ionic strength, of the binding buffer, and is supported by the characterization of the surface properties of particles and bacteria. The results demonstrate that electrostatic forces and hydrophobicity are responsible for the adhesion of target bacteria to the particles. Distinct advantages of the particle-based isolation strategy include simple handling, enrichment efficiency, and the preservation of viable bacteria. The presented isolation method allows a subsequent identification of the bacteria using Raman microspectroscopy in combination with chemometrical methods. This is demonstrated with a dataset of five different bacteria (Escherichia coli, Bacillus subtilis, Pseudomonas fluorescens, Streptomyces tendae, and Streptomyces acidiscabies) which were isolated from spiked soil samples. In total 92% of the Raman spectra could be identified correctly.
Keywords: Bacteria adhesion; Isolation of bacteria; Identification of bacteria; Soil samples; Raman spectroscopy; Poly(ethyleneimine) functionalization; Polyethylene particles
DNA nanopore functionalized with aptamer and cell-penetrating peptide for tumor cell recognition by Xi-Lin Guo; Dan-Dan Yuan; Ting Song; Xue-Mei Li (3789-3797).
In the present work, DNA nanopore was composed of a bundle of six DNA duplexes folded from six DNA strands and functionalized with Ramos cell aptamer and cell-penetrating peptide (CPP). Herein, we present a unique dually conjugated molecule with an aptamer and cell-penetrating peptide for targeting and recognition of Ramos cells. The aptamer sequence was specific bound to Ramos cell, at the meanwhile the nanopore assembly was taken onto the surface of cell membrane and then got into the cells with the help of CPP. Specific targeting and increased intracellular uptake of nanostructures by Ramos cells were aimed. The intracellular uptake of the structure was determined using confocal microscopy. This study is the first to describe the recognition of tumor cells with functional DNA nanopores, establishing the foundation for the tumor cell detection with low cytotoxic agents. Graphical abstract DNA nanopore was composed of a bundle of six DNA duplexes folded from six DNA strands and functionalized with Ramos cell aptamer and cell-penetrating peptide. The dually conjugated molecule was found to show both improved cellular uptake and effective Ramos cell targeting.
Keywords: DNA nanopore; Aptamer; Cell-penetrating peptide; Ramos cell
Disulfide-modified antigen for detection of celiac disease-associated anti-tissue transglutaminase autoantibodies by Luis Carlos Rosales-Rivera; Samuel Dulay; Pablo Lozano-Sánchez; Ioanis Katakis; Josep Lluís Acero-Sánchez; Ciara K. O’Sullivan (3799-3806).
A simple and rapid immunosensor for the determination of the celiac disease-related antibody, anti-tissue transglutaminase, was investigated. The antigenic protein tissue transglutaminase was chemically modified, introducing disulfide groups through different moieties of the molecule (amine, carboxylic, and hydroxyl groups), self-assembled on gold surfaces, and used for the detection of IgA and IgG autoantibodies. The modified proteins were evaluated using enzyme-linked immunosorbent assay and surface plasmon resonance, which showed that only introduction of the disulfide groups through amine moieties in the tissue transglutaminase preserved its antigenic properties. The disulfide-modified antigen was co-immobilized via chemisorption with a poly(ethylene glycol) alkanethiol on gold electrodes. The modified electrodes were then exposed to IgA anti-tissue transglutaminase antibodies and subsequently to horseradish peroxidase-labeled anti-idiotypic antibodies, achieving a detection limit of 260 ng ml−1. Immunosensor performance in the presence of complex matrixes, including clinically relevant serum reference solutions and real patient samples, was evaluated. The introduction of disulfides in the antigenic protein enabled a simple and convenient one-step surface immobilization procedure involving only spontaneous gold-thiol covalent binding. Complete amperometric assay time was 30 min.
Keywords: Electrochemical immunosensor; Modified proteins; Anti-tissue transglutaminase antibodies; Celiac disease
Tracing the fate and transport of secondary plant metabolites in a laboratory mesocosm experiment by employing mass spectrometric imaging by Anna C. Crecelius; Beate Michalzik; Karin Potthast; Stefanie Meyer; Ulrich S. Schubert (3807-3820).
Mass spectrometric imaging (MSI) has received considerable attention in recent years, since it allows the molecular mapping of various compound classes, such as proteins, peptides, glycans, secondary metabolites, lipids, and drugs in animal, human, or plant tissue sections. In the present study, the application of laser-based MSI analysis of secondary plant metabolites to monitor their transport from the grass leaves of Dactylis glomerata, over the crop of the grasshopper Chorthippus dorsatus to its excrements, and finally in the soil solution is described. This plant-herbivore-soil pathway was investigated under controlled conditions by using laboratory mesocosms. From six targeted secondary plant metabolites (dehydroquinic acid, quinic acid, apigenin, luteolin, tricin, and rosmarinic acid), only quinic acid, and dehydroquinic acid, an in-source-decay (ISD) product of quinic acid, could be traced in nearly all compartments. The tentative identification of secondary plant metabolites was performed by MS/MS analysis of methanol extracts prepared from the investigated compartments, in both the positive and negative ion mode, and subsequently compared with the results generated from the reference standards. Except for tricin, all secondary metabolites could be tentatively identified by this approach. Additional liquid-chromatography mass spectrometry (LC-MS) experiments were carried out to verify the MSI results and revealed the presence of quinic acid only in grass and chewed grass, whereas apigenin-hexoside-pentoside and luteolin-hexoisde-pentoside could be traced in the grasshopper body and excrement extracts. In summary, the MSI technique shows a trade-off between sensitivity and spatial resolution. Graphical abstract Monitoring quinic acid in a mesocosm experiment by mass spectrometric imaging (MSI).
Keywords: Laser desorption/ionization; Time-of-flight; Mass spectrometric imaging; Mesocosm; Secondary plant metabolites
Quantitative analysis of the cysteine redoxome by iodoacetyl tandem mass tags by Shakir Shakir; Joelle Vinh; Giovanni Chiappetta (3821-3830).
The redox conditions that reign inside a cell have a determining effect on a number of biological processes. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are key redox players and have been linked to a number of pathologies. They have also been shown to play an important regulating role in cell signaling events. On the proteome level, thiol groups of cysteinyl side chains constitute the major targets of ROS and RNS. A number of analytical techniques based on mass spectrometry have been developed to characterize the cysteine redoxome, often facing a number of technical challenges, mostly related to the lability, heterogeneity, and low abundance of the oxidized forms. Furthermore, any posttranslational modification (PTM) quantification method needs to take the parent protein’s expression level into account. While taking all these limitations into consideration, we have developed a quantitative analytical strategy named OxiTMT, based on chemical labeling with iodoacetyl isobaric tandem mass tags (iodoTMT). OxiTMT allowed the generation of quantitative redox data that could be normalized by the protein’s expression profile in up to three different conditions. The method was tested on Escherichia coli with or without an oxidative treatment. Results showed the method to be adequate for the analysis of cysteine PTMs with a good coverage of the cysteine redoxome, especially for the low abundant oxidized species. Some of the challenges that face reporter ion quantification of PTMs by mass spectrometry were also assessed. This study serves as a proof of concept of the established protocol and consequent data treatment step. The use of tandem mass tags opens the ways towards the application of the method to the study of tissues and sera. Graphical abstract OxiTMT workflow
Keywords: Redox proteomics; Cysteine oxidation; Tandem mass tags (TMT); Mass spectrometry
Dot immunoassay for the simultaneous determination of postvaccination immunity against pertussis, diphtheria, and tetanus by Pavel Khramtsov; Maria Bochkova; Valeria Timganova; Svetlana Zamorina; Mikhail Rayev (3831-3842).
A dot immunoassay for simultaneous semiquantitative detection of IgG against tetanus toxoid (Ttx) and diphtheria toxoid (Dtx) and qualitative detection of anti-Bordetella pertussis IgGs in human blood serum using carbon nanoparticles functionalized with streptococcal protein G was developed. Inactivated B. pertussis cells in suspension form were used as an antigen in the immunoassay. Pertussis, tetanus, and diphtheria antigens were separately spotted onto nitrocellulose strips, and then the immunostrips were successively incubated with blood sera and a suspension of carbon nanoparticles. The immunostrips were then scanned with a flatbed scanner, and the images obtained were processed with ImageJ. One hundred fifty-five venous blood serum samples from children vaccinated with diphtheria, tetanus, and whole-cell pertussis (DTwP) vaccine were tested in comparison with a conventional ELISA and agglutination test. The total time required for analysis of 32 serum samples was less than 3 h. Comparison between the results of the dot immunoassay and the corresponding ELISA/agglutination test revealed a high level of agreement (Cohen’s kappa between 0.765 and 0.813). The lower limit of quantification was 0.06 IU/ml for anti-Ttx and anti-Dtx. The intra-assay coefficients of variation were less than 15% for anti-Ttx and anti-Dtx and less than 10% for anti-pertussis. The diagnostic sensitivity of detection of the antibody protection level was 93.5% for anti-Ttx [95% confidence interval (CI) 83.5–97.9%], 92.4% for anti-Dtx (95% CI 80.9297.5%), and 90.2% for anti-pertussis (95% CI 75.9–96.8%). The diagnostic specificity was 90.9% for anti-Ttx (95% CI 57.1–99.5%), 85% for anti-Dtx (95% CI 61.1–96.0%), and 89.3% for anti-pertussis (95%CI 80.8–94.5%). The dot immunoassay developed does not require expensive reading equipment, and allows detection of antibodies against three antigens in a single analysis. The immunostrips can be stored for a long time without changes in the coloration of the spots. Graphical Abstract The assay procedure. BC Bordetella pertussis cell suspension, CNP carbon nanoparticle, Dtx diphtheria toxoid, Ttx tetanus toxoid
Keywords: Pertussis; Tetanus; Diphtheria; Dot immunoassay; Antibody; Carbon nanoparticles
Elemental quantitation of carbon via production of polyatomic anions in gas chromatography-plasma assisted reaction chemical ionization mass spectrometry by Peter J. Haferl; Kunyu Zheng; Haopeng Wang; Kaveh Jorabchi (3843-3851).
Elemental mass spectrometry offers quantitation and isotopic analysis without the need for compound-specific standards. We have recently introduced plasma assisted reaction chemical ionization (PARCI) as an efficient elemental ionization method for halogens. Here, we report a new ionization chemistry in PARCI for facile quantitation of elemental carbon in gas chromatography eluates. We demonstrate that in-plasma reactions of organic compounds followed by afterglow ionization lead to formation of polyatomic anions (CN−, OCN−, and CO3 −), among which CN− offers the best analytical sensitivity with a detection limit of ~25 pg (21 pg/s) carbon on column. Using a mixture of pesticides with wide variations in structures and heteroatom content, we demonstrate that CN− ion response is quantitatively correlated with the carbon concentration over two orders of magnitude (r 2 = 0.985). We show that the novel GC-PARCI-MS method provides recoveries within 80–120% using a single standard for all analytes, highlighting the strength of elemental quantitation. Further, the ability of GC-PARCI-MS to identify 13C-tagged molecules without a priori knowledge of chemical formulas of analytes is demonstrated. Graphical abstract ᅟ
Keywords: Elemental quantitation; Carbon; Compound-independent calibration; Mass spectrometry; Isotopic tagging
In situ X-ray fluorescence-based method to differentiate among red ochre pigments and yellow ochre pigments thermally transformed to red pigments of wall paintings from Pompeii by Iker Marcaida; Maite Maguregui; Silvia Fdez-Ortiz de Vallejuelo; Héctor Morillas; Nagore Prieto-Taboada; Marco Veneranda; Kepa Castro; Juan Manuel Madariaga (3853-3860).
Most of the magnificent wall paintings from the ancient city of Pompeii are decorated with red and yellow colors coming from the ochre pigments used. The thermal impact of the pyroclastic flow from the eruption of Vesuvius, in AD 79, promoted the transformation of some yellow painted areas to red. In this work, original red ochre, original yellow ochre, and transformed yellow ochre (nowadays showing a red color) of wall paintings from Pompeian houses (House of Marcus Lucretius and House of Gilded Cupids) were analyzed by means of a handheld energy-dispersive X-ray fluorescence spectrometer to develop a fast method that allows chemical differentiation of the original red ochre and the transformed yellow ochre. Principal component analysis of the multivariate obtained data showed that arsenic is the tracer element to distinguish between both red colored ochres. Moreover, Pompeian raw red and yellow ochre pigments recovered from the burial were analyzed in the laboratory with use of a benchtop energy-dispersive X-ray fluorescence spectrometer to confirm the elemental composition and the conclusions drawn from the in situ analysis according to the yellow ochre pigment transformation in real Pompeian wall paintings.
Keywords: Red ochre; Yellow ochre; Color transformation; Dehydration process; Arsenic traces; X-ray fluorescence spectrometry
Investigation of carbon-based nanomaterials as sorbents for headspace in-tube extraction of polycyclic aromatic hydrocarbons by Xochitli L. Osorio Barajas; Thorsten Hüffer; Pascal Mettig; Beat Schilling; Maik A. Jochmann; Torsten C. Schmidt (3861-3870).
Carbon-based nanomaterials (CNM) represent promising materials for the application as sorbents in micro- and other extraction devices. In this work, we investigate the applicability of five different CNM (multi-walled carbon nanotubes (MWCNTs), fullerenes, carboxylic acid functionalized multi-walled carbon nanotubes (MWCNTs-COOH), graphene platelets, and carbon nanohorns) for their performance on PAH extraction from the aqueous phase by headspace in-tube extraction (HS-ITEX). Optimal extraction parameters for HS-ITEX were determined using a Box-Behnken experimental design. From the extraction yield response, central point analysis, fullerenes showed the best extraction properties for the eight selected headspace compatible PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene). Fullerenes were used for a further method validation including the linear range, limit of detection, precision, as well as recovery. Finally, extraction yields were compared to a commercial material (Tenax GR), demonstrating that fullerene represents a better option as sorbent in ITEX for PAH analysis. Method detection limits for the PAH on fullerene ranged from 10 to 300 ng L−1, with recoveries between 45 and 103%.
Keywords: PAHs; Carbon-based nanomaterials; Headspace; ITEX; GC/MS; Box-Behnken design
A novel detection method of human serum albumin based on CuInZnS quantum dots-Co2+ sensing system by Wenying Gui; Xueqian Chen; Qiang Ma (3871-3876).
We developed a novel “turn off-on” sensor for human serum albumin (HSA) detection based on CuInZnS quantum dots (CIZS QDs). The photoluminescence (PL) of QDs can be “turned off” by Co(II) first. Because of the strong binding ability of HSA with Co2+, Co2+ can be removed from CIZS QDs with the addition of HSA. As a result, the PL of CIZS QDs probe can be “turned on” with an increased concentration of HSA over a wide range. The analyte HSA concentration had a proportional linear relationship with the recovered PL intensity of CIZS QDs. The detection limit for HSA was 4.5 × 10–8 mol L–1. The results indicated that the CIZS QDs- Co2+-BSA sensing system possessed higher sensitivity and better practicability for HSA detection.
Keywords: CuInZnS QDs; Human serum albumin (HSA); “Turn off-on”; Fluorescence assay
Semiautomated TaqMan PCR screening of GMO labelled samples for (unauthorised) GMOs by Ingrid M. J. Scholtens; Bonnie Molenaar; Richard A. van Hoof; Stephanie Zaaijer; Theo W. Prins; Esther J. Kok (3877-3889).
In most countries, systems are in place to analyse food products for the potential presence of genetically modified organisms (GMOs), to enforce labelling requirements and to screen for the potential presence of unauthorised GMOs. With the growing number of GMOs on the world market, a larger diversity of methods is required for informative analyses. In this paper, the specificity of an extended screening set consisting of 32 screening methods to identify different crop species (endogenous genes) and GMO elements was verified against 59 different GMO reference materials. In addition, a cost- and time-efficient strategy for DNA isolation, screening and identification is presented. A module for semiautomated analysis of the screening results and planning of subsequent event-specific tests for identification has been developed. The Excel-based module contains information on the experimentally verified specificity of the element methods and of the EU authorisation status of the GMO events. If a detected GMO element cannot be explained by any of the events as identified in the same sample, this may indicate the presence of an unknown unauthorised GMO that may not yet have been assessed for its safety for humans, animals or the environment.
Keywords: Screening; Specificity; Element; Construct; GMO; Automation
Video approach to chemiluminescence detection using a low-cost complementary metal oxide semiconductor (CMOS)-based camera: determination of paracetamol in pharmaceutical formulations by Luis Lahuerta-Zamora; Ana M. Mellado-Romero (3891-3898).
A new system for continuous flow chemiluminescence detection, based on the use of a simple and low-priced lens-free digital camera (with complementary metal oxide semiconductor technology) as a detector, is proposed for the quantitative determination of paracetamol in commercial pharmaceutical formulations. Through the camera software, AVI video files of the chemiluminescence emission are captured and then, using friendly ImageJ public domain software (from National Institutes for Health), properly processed in order to extract the analytical information. The calibration graph was found to be linear over the range 0.01–0.10 mg L−1 and over the range 1.0–100.0 mg L−1 of paracetamol, the limit of detection being 10 μg L−1. No significative interferences were found. Paracetamol was determined in three different pharmaceutical formulations: Termalgin®, Efferalgan® and Gelocatil®. The obtained results compared well with those declared on the formulation label and with those obtained through the official analytical method of British Pharmacopoeia. Graphical abstract Abbreviated scheme of the new chemiluminescence detection system proposed in this paper
Keywords: Flow chemiluminescence; CMOS camera; ImageJ; Pharmaceutical analysis
Letter to the Editor regarding “Analysis of recombinant human follicle-stimulating hormone by mass spectrometric approaches” by Clemens Grünwald-Gruber; Friedrich Altmann (3899-3900).