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Analytical and Bioanalytical Chemistry (v.395, #1)

Practical and effective networking by Patricia Ann Mabrouk (pp. 1-4).

is Professor of Chemistry & Chemical Biology at Northeastern University (Boston, MA). Her research interests are chemical education (graduate education, active learning, and undergraduate research), green chemistry, and bioanalytical chemistry.

Practical and effective networking by Patricia Ann Mabrouk (pp. 1-4).

Random error propagation challenge by Juris Meija (pp. 5-6).

Solution to Mendeleyev vodka challenge by Juris Meija (pp. 7-8).

Séverine Le Gac, Albert van den Berg (Eds.): Miniaturization and mass spectrometry by Freddy Adams (pp. 9-10).

3rd International IUPAC Symposium on Trace Elements in Food by Francesco Cubadda (pp. 11-13).

Allergens in foods by Angelika Paschke; Franz Ulberth (pp. 15-16).

is a researcher and lecturer in food chemistry at the University of Hamburg, Germany. Her research topic is food allergy, isolation and characterization of allergens, and their alteration during technological treatment of food. is head of the Food Safety and Quality Unit of the European Commission's Joint Research Centre, Institute for Reference Materials and Measurements, which is located in Geel, Belgium.

Allergens in foods by Angelika Paschke; Franz Ulberth (pp. 15-16).

Food anaphylaxis by Knut Brockow; Johannes Ring (pp. 17-23).

is attending physician at the Department of Dermatology and Allergy Biederstein, Technische Universität München, Munich, Germany. He has been working for many years in the Allergy Department and also supervises the testing and provocation tests of children with food allergy. His main clinical and research interests are drug hypersensitivity, mastocytosis, and other mast cell diseases, such as anaphylaxis is the Director and Chairman of the Department of Dermatology and Allergy Biederstein, Technische Universität München, Munich, Germany. He has been working in the field of food allergy for many years and was the former president of the German Society for Allergy and Clinical Immunology (DGAKI) and of the Collegium Internationale Allergologicum (CIA) Figure Avoidance is the primary measure in food allergy confirmed

Food anaphylaxis by Knut Brockow; Johannes Ring (pp. 17-23).

Food allergen protein families and their structural characteristics and application in component-resolved diagnosis: new data from the EuroPrevall project by Karin Hoffmann-Sommergruber; E. N. Clare Mills (pp. 25-35).

A large number of food allergens able to induce allergic symptoms in predisposed individuals, including severe, even life-threatening reactions, have been identified and characterized. However, proteins able to cause such IgE-mediated reactions can be assigned to only a limited number of protein families. Detailed knowledge about the characteristics of food allergens, their 3D structures, biological activity and stability, will help to improve diagnosis of food allergy, avoid unnecessary exclusion diets and assess the risk of cross-reactive allergies to other food sources. This review is dedicated to summarizing current knowledge about the most important food allergen protein families and to presenting data from the EuroPrevall allergen library, a proof-of-concept collection of highly purified, characterized and authenticated food allergens from animal and plant food sources to facilitate improved diagnosis of food allergies. Relevant food allergen sources

Keywords: Food allergen; Purification; Allergen library; Cross-reactivity; Protein family

Immunomodulation by food: promising concept for mitigating allergic disease? by Harry Wichers (pp. 37-45).

The importance of a properly functioning and well-balanced immune system for maintaining health has become strikingly evident over the past decades. Roughly since World War II, there has been an apparent decrease in the prevalence of “traditional” infectious diseases, with a concomitant increase in immune-related disorders, such as allergies. Causally, a relationship with changes in life-style-related factors such as the increasing use of hygienic practices seems likely. Diet and nutrition can affect the functioning of various immune parameters. This concept can be utilised in attempts to prevent or mitigate allergic reactions via the development of targeted food products or ingredients. This review describes recent findings with respect to food products and ingredients that show potential in this respect, with special emphasis on pro- and prebiotics, β-glucans and fungal immunomodulatory proteins. What all of these approaches have in common is that they appear to strengthen Th1-mediated immunity, thus possibly restoring defective immune maturation due to overly hygienic living conditions: a little bit of dirt does not seem bad!

Keywords: Immunity; Immunomodulation; Allergy; Probiotics; Prebiotics; β-Glucans; Fungal immunomodulatory proteins; Diet; Nutrition

Immunomodulation by food: promising concept for mitigating allergic disease? by Harry Wichers (pp. 37-45).

Keywords: Immunity; Immunomodulation; Allergy; Probiotics; Prebiotics; β-Glucans; Fungal immunomodulatory proteins; Diet; Nutrition

Molecular aspects of milk allergens and their role in clinical events by Patrizia Restani; Cinzia Ballabio; Chiara Di Lorenzo; Salvatore Tripodi; Alessandro Fiocchi (pp. 47-56).

Milk allergy is the most frequent food allergy in childhood. Even though cases of newly developed milk allergy in adulthood are known, this allergy is less frequent in adults since it is normally outgrown by children during the first years of life. One of the reasons why allergy to cow’s milk shows its highest prevalence in children is its early introduction into the diets of babies when breast feeding is not possible. The major allergens are caseins and β-lactoglobulin, but allergies to other minor proteins (immunoglobulins, bovine serum albumin) have also been reported. Milk allergenicity can be reduced by various treatments (mainly hydrolysis), meaning that formulas based on cow’s milk can often be safely fed to children allergic to milk proteins. Cross-reactivity has been described between different mammalian milks and between milk and meat or animal dander. Cross-contamination can result from inadequate cleaning of industrial equipment and constitutes a hidden danger for allergic subjects who unknowingly ingest milk proteins. Figure Involvement (expressed as percentage of total subjects) of the most abundant milk proteins in the sensitization of 80 children allergic to cow’s milk. The upper panel includes all positive responses, even minor ones; data in the lower panel are restricted to the most severe positive responses (see text for details). SPT, skin prick test; CAP, CAP test; IMM, immunoblotting; alpha-LA, α-lactalbumin; beta-LG, β-lactoglobulin; cas, caseins; BSA, bovine serum albumin

Keywords: Milk allergy; Caseins; Whey proteins; Serum albumins; Cross-reactivity; Technological treatments

Molecular aspects of milk allergens and their role in clinical events by Patrizia Restani; Cinzia Ballabio; Chiara Di Lorenzo; Salvatore Tripodi; Alessandro Fiocchi (pp. 47-56).

Keywords: Milk allergy; Caseins; Whey proteins; Serum albumins; Cross-reactivity; Technological treatments

Quantitative methods for food allergens: a review by Stéphanie Kirsch; Séverine Fourdrilis; Rowan Dobson; Marie-Louise Scippo; Guy Maghuin-Rogister; Edwin De Pauw (pp. 57-67).

The quantitative detection of allergens in the food chain is a strategic health objective as the prevalence of allergy continues to rise. Food allergenicity is caused by proteins either in their native form or in forms resulting from food processing. Progress in mass spectrometry greatly opened up the field of proteomics. These advances are now available for the detection and the quantification of traces of allergenic proteins in complex mixtures, and complete the set of biological tests used until now, such as ELISA or PCR. We review methods classified according to their ability to simultaneously quantify and identify allergenic proteins and underline major advances in the mass-spectrometric methods.

Keywords: Absolute quantification; Allergenic protein; Cross-contamination; ELISA; Isotopically labelled peptide; Label free; Mass spectrometry; PCR; Tagging

Quantitative methods for food allergens: a review by Stéphanie Kirsch; Séverine Fourdrilis; Rowan Dobson; Marie-Louise Scippo; Guy Maghuin-Rogister; Edwin De Pauw (pp. 57-67).

Keywords: Absolute quantification; Allergenic protein; Cross-contamination; ELISA; Isotopically labelled peptide; Label free; Mass spectrometry; PCR; Tagging

Commercialized rapid immunoanalytical tests for determination of allergenic food proteins: an overview by Patricia Schubert-Ullrich; Judith Rudolf; Parisa Ansari; Brigitte Galler; Manuela Führer; Alexandra Molinelli; Sabine Baumgartner (pp. 69-81).

Food allergies have become an important health issue especially in industrialized countries. Undeclared allergenic ingredients or the presence of “hidden” allergens because of contamination during the food production process pose great health risks to sensitised individuals. The EU directive for food labelling lists allergenic foods that have to be declared on food products by the manufacturers. The list includes gluten-containing cereals, crustaceans, eggs, fish, peanuts, soybeans, milk, various nuts (e.g. almond, hazelnut, and walnut, etc.), celery, mustard, sesame seeds, lupin, and molluscs. Reliable methods for detection and quantification of food allergens are needed that can be applied in a fast and easy-to-use manner, are portable, and need only limited technical equipment. This review focuses on the latest developments in food allergen analysis with special emphasis on fast immunoanalytical methods such as rapid enzyme-linked immunosorbent assays (ELISA), lateral-flow immunochromatographic assays (LFA) and dipstick tests. Emerging technologies such as immunochemical microarrays and biosensors are also discussed and their application to food allergen analysis is reviewed. Finally, a comprehensive overview of rapid immunochemical test kits that are currently available commercially is given in tabular form.

Keywords: Immunoassay; Strip tests; Microarray; Biosensors; Surface plasmon resonance; Resonance-enhanced absorption

Allergen immunoassays—considerations for use of naturally incurred standards by Steve L. Taylor; Julie A. Nordlee; Lynn M. Niemann; Debra M. Lambrecht (pp. 83-92).

The enzyme-linked immunosorbent assay (ELISA) offers many advantages for the detection of potentially hazardous allergenic food residues that might become adventitious components of other foods during the course of food production and processing. ELISAs detect proteins, and food allergens are proteins. ELISAs are sufficiently sensitive and specific for detection of food allergen residues. ELISAs can also be produced in formats that are compatible with the industrial food processing environment. However, ELISAs also have disadvantages that should be carefully evaluated and widely recognized. Various food-processing operations can have profound effects on the detectability of allergenic food residues. ELISAs detect intact proteins but protein hydrolysates evade detection in some ELISA formats. The residual proteins present in some ingredients derived from commonly allergenic sources may also not be easily detected with ELISAs because of the nature of the protein residues remaining, e.g. lipophilic. Processing operations can dramatically lower the solubility of proteins. In some food formulations, heat processing, in particular, induces chemical modifications that can affect antibody binding to epitopes in the ELISA. The use of naturally incurred standards where allergenic food residues are incorporated into various representative food matrices and then processed in a manner similar to “real-world” food processing can reveal some of the limitations of allergen ELISAs. Methods for the preparation of naturally incurred standards in chocolate, cookie, muffin, ice cream, pasta, frankfurter, and cream of potato soup are provided as examples.

Keywords: Allergen; Food; Immunoassay; ELISA; Validation; Incurred

Allergen immunoassays—considerations for use of naturally incurred standards by Steve L. Taylor; Julie A. Nordlee; Lynn M. Niemann; Debra M. Lambrecht (pp. 83-92).

Keywords: Allergen; Food; Immunoassay; ELISA; Validation; Incurred

Maize food allergy: lipid-transfer proteins, endochitinases, and alpha-zein precursor are relevant maize allergens in double-blind placebo-controlled maize-challenge-positive patients by Elide A. Pastorello; Laura Farioli; Valerio Pravettoni; Joseph Scibilia; Amedeo Conti; Donatella Fortunato; Linda Borgonovo; Simona Bonomi; Laura Primavesi; Barbara Ballmer-Weber (pp. 93-102).

Italian patients with maize anaphylaxis have been shown to have IgE toward two major maize allergens: an alpha-amylase inhibitor and a 9-kDa LTP. A complete study on maize food allergens in patients with positive maize double-blind, placebo-controlled food challenge (DBPCFC) is lacking. The objective was to utilize the three maize protein fractions to identify and characterize the most relevant IgE-binding proteins recognized by the sera of Italian and Swiss patients with either a positive maize-DBPCFC or a history of maize-induced anaphylaxis. Osborne’s protein fractions of maize were extracted to obtain water-soluble, total zein, and total protein fractions. Protein IgE-binding capacity was investigated by SDS-PAGE immunoblotting using the sera from DBPCFC-positive patients and from patients with maize-induced anaphylaxis. Purified maize LTP was used to inhibit the IgE immunoblotting of the three protein fractions. IgE immunoblotting demonstrated that the 9-kDa LTP was recognized by all the Italian patients and by none of the Swiss patients. Other allergens were: 14-kDa α-amylase inhibitor, 30-kDa endochitinases A and -B, 19 kDa zein-β precursor, and 26 kDa zein-α precursor; a newly described allergen, the globulin-2 precursor, identified in the total protein fraction. It is noteworthy that maize LTP and endochitinase were cross-reactive with grape LTP and one grape endochitinase. LTP was found to be the only major allergen in Italian patients with either positive maize challenge or a history of maize-induced anaphylaxis. We have identified other maize allergens in subjects with maize food allergy, as grape cross-reactive endochitinase, however, the clinical significance of these proteins needs to be investigated in larger groups of patients with allergy to these food items.

Keywords: Maize allergens; Grape allergens; Grape cross-reactivity; Double-blind placebo-controlled food challenge; Maize anaphylaxis; Lipid transfer proteins; LTP

Commercial lateral flow devices for rapid detection of peanut (Arachis hypogaea) and hazelnut (Corylus avellana) cross-contamination in the industrial production of cookies by Martin Röder; Stefan Vieths; Thomas Holzhauser (pp. 103-109).

Lateral flow devices (LFDs) are qualitative immunochromatographic tests for the rapid and specific detection of target analytes. We investigated commercially available LFDs for their ability to detect potentially allergenic peanut and hazelnut in raw cookie dough and chocolate, two important food matrices in the industrial production of cookies. Each three commercial LFDs for the detection of hazelnut and peanut were performed according to the manufacturers’ instructions. All LFDs had comparably satisfactory specificity that was investigated with a variety of characteristic foods and food ingredients used in the production of cookies. In concordance with hazelnut-specific enzyme-linked immunosorbent assays (ELISAs), walnut was the most cross-reactive food for hazelnut-specific LFD. The sensitivity was verified in raw cookie doughs and chocolates that were either spiked with peanut or hazelnut between 1 and 25 mg/kg, respectively. Two hazelnut-specific LFDs detected hazelnut at a level of 3.5 mg/kg in both matrices, whereas the third LFD detected hazelnut at a level of 3.9 mg/kg in dough and 12.5 mg/kg in chocolate. Two peanut-specific LFDs detected peanut at a level of 1 mg/kg in both matrices. The third LFD detected peanut at a level of 14.2 mg/kg in chocolate and 4 mg/kg in dough. In conclusion, specific and sensitive LFD were identified for each hazelnut and peanut, having a level of sensitivity that is comparable to commercial ELISA for the investigated matrices. Such sensitive, specific, and rapid tests are useful analytical tools for allergen screening and sanitation in the industrial manufacture of foods.

Keywords: Lateral flow device (LFD); Hazelnut (Corylus avellana) ; Peanut (Arachis hypogaea) ; Cookies; Monitoring cross-contamination; Hidden allergens

Emerging analytical methods to determine gluten markers in processed foods—method development in support of standard setting by Dorcas Weber; Chantal Cléroux; Samuel Benrejeb Godefroy (pp. 111-117).

The availability of analytical methods to detect and determine levels of markers of priority allergens in foods is of the utmost importance to support standard setting initiatives, the development of compliance and enforcement activities, as well as to provide guidance to industry on implementation of quality control practices, ensuring the effectiveness of allergen-related sanitation techniques. This paper describes the development and implementation of a mass-spectrometry-based technique to determine markers for individual sources of gluten in beer products. This methodology was shown to answer the requirements of Health Canada’s proposed labeling standard for individual gluten source declaration, in order to achieve its policy objectives (i.e., protection of sensitive consumers, while promoting choice). Minimal sample work-up was required and the results obtained by ELISA were further complemented using the LC-MS/MS method. This paper aims to demonstrate the feasibility of alternative techniques to ELISA-based methodologies to determine allergen and gluten markers in food.

Keywords: Immunoassays; ELISA; Bioanalytical methods; Foods; Beverages; Mass spectrometry

Biosensor immunoassay for traces of hazelnut protein in olive oil by Maria G. E. G. Bremer; Nathalie G. E. Smits; Willem Haasnoot (pp. 119-126).

The fraudulent addition of hazelnut oil to more expensive olive oil not only causes economical loss but may also result in problems for allergic individuals as they may inadvertently be exposed to potentially allergenic hazelnut proteins. To improve consumer safety, a rapid and sensitive direct biosensor immunoassay, based on a highly specific monoclonal antibody, was developed to detect the presence of hazelnut proteins in olive oils. The sample preparation was easy (extraction with buffer); the assay time was fast (4.5 min only) and the limit of detection was low (0.08 μg/g of hazelnut proteins in olive oil). Recoveries obtained with an olive oil mixed with different amounts of a hazelnut protein containing hazelnut oil varied between 93% and 109%.

Keywords: Biosensor; Immunoassay; Monoclonal antibody; Olive oil; Hazelnut oil; Hidden allergens

Biosensor immunoassay for traces of hazelnut protein in olive oil by Maria G. E. G. Bremer; Nathalie G. E. Smits; Willem Haasnoot (pp. 119-126).

Keywords: Biosensor; Immunoassay; Monoclonal antibody; Olive oil; Hazelnut oil; Hidden allergens

The effect of heat treatment on the detection of peanut allergens as determined by ELISA and real-time PCR by Elena Scaravelli; Marcel Brohée; Rosangela Marchelli; Arjon J. van Hengel (pp. 127-137).

Peanut allergic reactions can result from the ingestion of even very small quantities of peanut and represent a severe threat to the health of sensitised individuals. The detection of peanut traces in food products is therefore of prime importance. Peanut traces which can be (unintentionally) present in food products have usually undergone one or more processing steps like roasting and baking. Therefore, methods designed to detect such traces have to be capable of detecting heat-treated peanuts. Commonly used methodologies designed to detect peanut traces in food products are enzyme-linked immunosorbent assays (ELISAs) that detect peanut-specific proteins, and polymerase-chain-reaction (PCR)-based methods targeting peanut-specific DNA. A comparative analysis of such methods was performed and the impact of heat treatment on peanut kernels as well as the impact on a peanut-containing food matrix are investigated. Our results show that heat treatments have a detrimental effect on the detection of peanut with either type of method and that both types of methods are affected in a similar manner.

Keywords: Real-time PCR; ELISA; Food allergy; Peanut; Heat treatment

Immunochemical characterisation of structure and allergenicity of peanut 2S albumins using different formats of immunoassays by Hervé Bernard; Marie-Françoise Drumare; Blanche Guillon; Evelyne Paty; Pierre Scheinmann; Jean-Michel Wal (pp. 139-146).

Proteins of the 2S albumin family, such as Ara h2 and Ara h6, are most frequently involved in peanut allergy. We have developed a reverse enzyme allergo-sorbent test (EAST) in which total serum IgE antibodies are first captured by immobilised anti-human IgE monoclonal antibodies, and then the binding of the anti-Ara h2 and anti-Ara h6 specific IgE to the corresponding labelled allergens is measured. This reverse immunoassay was used either as a direct EAST or as an EAST inhibition assay to study the interactions of whole peanut protein extract and purified Ara h2 and Ara h6 with IgE antibodies from peanut-allergic patients. Finally, we identified some IgE-binding epitopes on Ara h6 using a format of EAST in which the protein is immobilised in a particular, well defined, manner through interactions with specific monoclonal antibodies (mAbs) coated on the micro-plates. The fine specificity of those mAbs has been characterised at the epitope level, and their binding to the allergen thus masks a known particular epitope and makes it unavailable for recognition by IgE antibodies. The reverse EAST increased the ratio specific signal/background. It avoids interferences with competitors such as anti-peanut protein IgG antibodies and allows the study of the specificity and/or affinity of the interactions between IgE antibodies and Ara h2 or Ara h6 with a higher sensitivity and accuracy than the conventional EAST. The EAST results obtained when the allergens are presented by specific mAbs suggest that the homologous molecular domain(s) in peanut 2S albumins encompass major IgE epitope(s) and are strongly involved in peanut allergenicity.

Keywords: Allergy; Peanut 2S albumins; Specific IgE antibodies; Reverse immunoassay; Immuno-cross-reactivity

Proficiency testing for quality assurance of allergens methods by Linda Owen; John Gilbert (pp. 147-153).

Proficiency testing is an external quality control check, whereby the quality of an analytical result is checked against criteria that are set independently of the laboratory carrying out the analysis. Participants in a proficiency test are encouraged to use the method of their choice to determine the analyte in question. The collated results submitted by the participants are used to derive the best estimate of the ‘true’ level, or assigned value, of the analyte, as a consensus value of the whole data set. Generally, the data submitted will be normally distributed and from a single population, but if a data set is found to be multimodal, then the selection of one of the modes as the assigned value is possible where there is supporting data, typically methodology information. Unless there are independent grounds for preferring one mode over another, it is not possible to set an assigned value or calculate z-scores. However, the analysis of allergens has presented proficiency testers with a new challenge, since it has become apparent that quantitative results may be dependent on the brand of enzyme-linked immunosorbent assay kit used, the specific analyte targeted (e.g. total content or allergen protein content) and the limit of detection achievable. FAPAS® has run more than 40 proficiency tests for allergen analysis over the past 7 years, during which time methods have been developed and improved and the requirements for determination of food ingredient allergens has increased. Two case studies are presented which highlight some of the issues around the use of allergen measurement methods. Figure A selection of food items which might cause allergenic or intolerance reactions

Keywords: Allergens; ELISA kits; Proficiency testing; Hazelnut; Sesame

Proficiency testing for quality assurance of allergens methods by Linda Owen; John Gilbert (pp. 147-153).

Keywords: Allergens; ELISA kits; Proficiency testing; Hazelnut; Sesame

Demonstrating the comparability of certified reference materials by David L. Duewer; Katrice A. Lippa; Stephen E. Long; Karen E. Murphy; Katherine E. Sharpless; Lorna T. Sniegoski; Michael J. Welch; Wataru Tani; Masao Umemoto (pp. 155-169).

Certified reference materials (CRMs) enable the meaningful comparison of measurement results over time and place. When CRMs are used to calibrate or verify the performance of a measurement system, results produced by that system can be related through the CRM to well-defined, stable, and globally accessible reference(s). Properly done, this directly establishes the metrological traceability of the results. However, achieving the meaningful comparison of results from measurement systems calibrated and/or verified with different CRMs requires that the different materials truly deliver the same measurand, that is, are “the same” within stated uncertainty except for differences in the level of the analyte of interest. We here detail experimental and data analysis techniques for establishing and demonstrating the comparability of materials. We focus on (1) establishing a uniform interpretation of the common forms of CRM uncertainty statements, (2) estimating consistent measurement system response uncertainties from sometimes inconsistent experimental designs, (3) using “errors-in-variables” analysis methods to evaluate comparability studies and novel graphical tools for communicating results of the evaluation to reviewing authorities and potential CRM customers, and (4) augmenting established comparability studies with new materials using measurements provided by the certifying institution. These experimental and data analytic tools were developed in support of the Joint Committee for Traceability in Laboratory Medicine’s efforts to enhance the reliability of clinical laboratory measurements and are illustrated with potassium and cholesterol measurands of clinical relevance; however, these tools can be applied to any group of materials that deliver the same nominal measurand with stated value and uncertainty.

Keywords: Certified reference material (CRM); Cholesterol in human serum; Errors-in-variables regression; Graphical communication; Joint Committee on Traceability in Laboratory Medicine (JCTLM); Metrological traceability; Potassium in human serum

Matisse to Picasso: a compositional study of modern bronze sculptures by Marcus L. Young; Suzanne Schnepp; Francesca Casadio; Andrew Lins; Melissa Meighan; Joseph B. Lambert; David C. Dunand (pp. 171-184).

Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to determine the bulk metal elemental composition of 62 modern bronze sculptures cast in Paris in the first half of the twentieth century from the collections of The Art Institute of Chicago and the Philadelphia Museum of Art. As a result, a comprehensive survey of the alloy composition of the sculptures of many prominent European artists of the early twentieth century is presented here for the first time. The sculptures in this study consist of predominantly copper with two main alloying elements (zinc and tin). By plotting the concentrations of these two elements (zinc and tin) against each other for all the sculptures studied, three clusters of data become apparent: (A) high-zinc brass; (B) low-zinc brass; (C) tin bronze. These clusters correlate to specific foundries, which used specific casting methods (sand or lost wax) that were influenced by individual preferences and technical skills of the foundry masters. For instance, the high-zinc brass alloys (with the highest levels of tin and zinc and the lowest melting temperature) correspond to most of the Picasso sculptures, correlate with the Valsuani foundry, and are associated with the most recent sculptures (post-WWII) and with the lost-wax casting method. By expanding the ICP-OES database of objects studied, these material correlations may become useful for identifying, dating, or possibly even authenticating other bronzes that do not bear foundry marks. Figure

Keywords: Bronze sculpture; ICP-OES; Modern bronze

Engineered 3D tissue models for cell-laden microfluidic channels by Young S. Song; Richard L. Lin; Grace Montesano; Naside G. Durmus; Grace Lee; Seung-Schik Yoo; Emre Kayaalp; Edward Hæggström; Ali Khademhosseini; Utkan Demirci (pp. 185-193).

Delivery of nutrients and oxygen within three-dimensional (3D) tissue constructs is important to maintain cell viability. We built 3D cell-laden hydrogels to validate a new tissue perfusion model that takes into account nutrition consumption. The model system was analyzed by simulating theoretical nutrient diffusion into cell-laden hydrogels. We carried out a parametric study considering different microchannel sizes and inter-channel separation in the hydrogel. We hypothesized that nutrient consumption needs to be taken into account when optimizing the perfusion channel size and separation. We validated the hypothesis by experiments. We fabricated circular microchannels (r = 400 μm) in 3D cell-laden hydrogel constructs (R = 7.5 mm, volume = 5 ml). These channels were positioned either individually or in parallel within hydrogels to increase nutrient and oxygen transport as a way to improve cell viability. We quantified the spatial distribution of viable cells within 3D hydrogel scaffolds without channels and with single- and dual-perfusion microfluidic channels. We investigated quantitatively the cell viability as a function of radial distance from the channels using experimental data and mathematical modeling of diffusion profiles. Our simulations show that a large-channel radius as well as a large channel to channel distance diffuse nutrients farther through a 3D hydrogel. This is important since our results reveal that there is a close correlation between nutrient profiles and cell viability across the hydrogel.

Keywords: 3D tissue engineering; Tissue perfusion; Microfluidic channel; Scaffold

Quantification of Paraquat, MPTP, and MPP⁺ in brain tissue using microwave-assisted solvent extraction (MASE) and high-performance liquid chromatography–mass spectrometry by Bozena Winnik; Dana B. Barr; Mona Thiruchelvam; M. Angela Montesano; Eric K. Richfield; Brian Buckley (pp. 195-201).

Animal models, consistent with the hypothesis of direct interaction of paraquat (PQ) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) with specific areas of the central nervous system have been developed to study Parkinson’s disease (PD) in mice. These models have necessitated the creation of an analytical method for unambiguous identification and quantitation of PQ and structurally similar MPTP and 1-methyl-4-phenylpyridinium ion (MPP⁺) in brain tissue. A method for determination of these compounds was developed using microwave-assisted solvent extraction (MASE) and liquid chromatography–mass spectrometry. Extraction solvent and microwave conditions such as power and time were optimized to produce recoveries of 90% for PQ 78% for MPTP and 97% for its metabolite MPP⁺. The chromatographic separation was performed on a C8, column and detection was carried out using an ion trap as an analyzer with electrospray ionization. Mass spectrometer parameters such as heated capillary temperature, spray voltage, capillary voltage and others were also optimized for each analyte. Analysis was done in selective ion-monitoring (SIM) mode using m/z 186 for PQ, m/z 174 for MPTP, and m/z 170 for MPP⁺. The method detection limit for paraquat in matrix was 100 pg, 40 pg for MPTP, and 20 pg MPP⁺.

Keywords: Paraquat; MPTP; MPP+; Tissue; Microwave solvent extraction; HPLC; Mass spectrometry; Electrospray ionization

Determination of fifteen active compounds released from paraffin-based active packaging in tomato samples via microextraction techniques by Angel Rodriguez-Lafuente; Cristina Nerin de la Puerta; Ramón Batlle (pp. 203-211).

Automated headspace solid-phase microextraction (HS-SPME) and hollow-fibre liquid-phase microextraction (HFLPME) methods for the determination of 15 active chemicals released from essential-oil-based active packaging have been considered. The HS-SPME procedure demonstrates good performance and was therefore optimised and validated, providing detection limits in the low microgram per kilogramme range and wide and convenient linear ranges from 40.0 to 900.0 µg/kg. Extraction temperature has been demonstrated to be the most critical experimental parameter requiring accurate monitoring.

Keywords: Headspace solid-phase microextraction (HS-SPME); Hollow-fibre liquid-phase microextraction (HFLPME); Active packaging; Food analysis; Essential oils; Antimicrobial packaging

A solution to the 1D NMR alignment problem using an extended generalized fuzzy Hough transform and mode support by Erik Alm; Ralf J. O. Torgrip; K. Magnus Åberg; Ina Schuppe-Koistinen; Johan Lindberg (pp. 213-223).

This paper approaches the problem of intersample peak correspondence in the context of later applying statistical data analysis techniques to 1D ¹H-nuclear magnetic resonance (NMR) data. Any data analysis methodology will fail to produce meaningful results if the analyzed data table is not synchronized, i.e., each analyzed variable frequency (Hz) does not originate from the same chemical source throughout the entire dataset. This is typically the case when dealing with NMR data from biological samples. In this paper, we present a new state of the art for solving this problem using the generalized fuzzy Hough transform (GFHT). This paper describes significant improvements since the method was introduced for NMR datasets of plasma in Csenki et al. (Anal Bioanal Chem 389:875-885, 15) and is now capable of synchronizing peaks from more complex datasets such as urine as well as plasma data. We present a novel way of globally modeling peak shifts using principal component analysis, a new algorithm for calculating the transform and an effective peak detection algorithm. The algorithm is applied to two real metabonomic ¹H-NMR datasets and the properties of the method are compared to bucketing. We implicitly prove that GFHT establishes the objectively true correspondence. Desirable features of the GFHT are: (1) intersample peak correspondence even if peaks change order on the frequency axis and (2) the method is symmetric with respect to the samples. Figure From chaos to order: heatmaps of a H-NMR spectral segment prior and post sorting on one peak position. Post sorting sample order reveals that peak positions exhibits distinctive patterns which are modeled by the GFHT to establish correspondence.

Keywords: Metabolic profiling; NMR; Peak detection; Image processing; Hough transform; Synchronization; Alignment

Using the solvation parameter model to characterize functionalized ionic liquids containing the tris(pentafluoroethyl)trifluorophosphate (FAP) anion by Qichao Zhao; Jens Eichhorn; William R. Pitner; Jared L. Anderson (pp. 225-234).

Ionic liquids (ILs) containing the tris(pentafluoroethyl)trifluorophosphate anion [FAP]⁻ have attracted increased attention due to their unique properties including ultrahigh hydrophobicity, hydrolytic stability, and wide electrochemical window. In this study, the solvation parameter model is used via gas chromatography to characterize the solvation interactions of seven ILs containing amino, ester, and hydroxyl functional groups appended to the cation and paired with [FAP]⁻, as well as three ILs containing the bis[(trifluoromethyl)sulfonyl]imide anion [NTf₂]⁻. The role of the functional groups, nature of the counter anion, and cation type on the system constants were evaluated. ILs containing [FAP]⁻ possessed lower hydrogen bond basicity than NTf₂-based ILs having the same cationic component; in the case of hydroxyl-functionalized cations, the presence of [FAP]⁻ led to an enhancement of the hydrogen bond acidity, relative to the NTf₂-analogs. The system constants support the argument that [FAP]⁻ weakly coordinates the cation and any appended functional groups, promoting properties of the cation which might be masked by stronger interactions with other anion systems. The chromatographic performance of the IL stationary phases was evaluated by examining the retention behavior and separation selectivity for chosen analytes. The results from this work can be used as a guide for choosing FAP-based ILs capable of exhibiting desired solvation properties while retaining important physical properties including high thermal stability and high hydrophobicity. Figure In this study, the solvation parameter model is used via gas chromatography to characterize the solvation interactions of seven ILs containing amino, ester, and hydroxyl functional groups appended to the cation and paired with tris(pentafluoroethyl)trifluorophosphate [FAP]⁻, as well as three ILs containing the bis[(trifluoromethyl)sulfonyl]imide anion [NTf₂]⁻.

Keywords: Ionic liquid; Functionalized ionic liquid; Gas chromatography; Stationary phase; Selectivity; Tris(pentafluoroethyl)trifluorophosphate; FAP; Solvation

Fluorescence of sanguinarine: fundamental characteristics and analysis of interconversion between various forms by Marika Janovská; Martin Kubala; Vilím Šimánek; Jitka Ulrichová (pp. 235-240).

The quaternary isoquinoline alkaloid, sanguinarine (SG) plays an important role in both traditional and modern medicine, exhibiting a wide range of biological activities. Under physiological conditions, there is an equilibrium between the quaternary cation (SG⁺) and a pseudobase (SGOH) forms of SG. In the gastrointestinal tract, SG is converted to dihydrosanguinarine (DHSG). All forms exhibit bright fluorescence. However, their spectra overlap, which limited the use of powerful techniques based on fluorescence spectroscopy/microscopy. Our experiments using a combination of steady-state and time-resolved techniques enabled the separation of individual components. The results revealed that (a) the equilibrium constant between SG⁺ and SGOH is pK _a = 8.06, while fluorescence of DHSG exhibited no changes in the pH range 5–12, (b) the SGOH has excitation/emission spectra with maxima at 327/418 nm and excited-state lifetime 3.2 ns, the spectra of the SG⁺ have maxima at 475/590 nm and excited-state lifetime 2.4 ns. The DHSG spectra have maxima at 327/446 nm and 2-exponential decay with components 4.2 and 2.0 ns, (c) NADH is able to convert SG to DHSG, while there is no apparent interaction between NADH and DHSG. These techniques are applicable for monitoring the SG to DHSG conversion in hepatocytes.

Keywords: Sanguinarine; Dihydrosanguinarine; Fluorescence; Decay-associated spectra; Acido-basic equilibrium; Hepatocytes

Fluorescence of sanguinarine: fundamental characteristics and analysis of interconversion between various forms by Marika Janovská; Martin Kubala; Vilím Šimánek; Jitka Ulrichová (pp. 235-240).

Keywords: Sanguinarine; Dihydrosanguinarine; Fluorescence; Decay-associated spectra; Acido-basic equilibrium; Hepatocytes

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Analytical and Bioanalytical Chemistry (v.395, #1)

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Analytical and Bioanalytical Chemistry (v.395, #1)