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Sample records for 13c-label tracing phase

  1. Computational Platform for Flux Analysis Using 13C-Label Tracing- Phase I SBIR Final Report

    Van Dien, Stephen J.

    2005-04-12

    Isotopic label tracing is a powerful experimental technique that can be combined with metabolic models to quantify metabolic fluxes in an organism under a particular set of growth conditions. In this work we constructed a genome-scale metabolic model of Methylobacterium extorquens, a facultative methylotroph with potential application in the production of useful chemicals from methanol. A series of labeling experiments were performed using 13C-methanol, and the resulting distribution of labeled carbon in the proteinogenic amino acids was determined by mass spectrometry. Algorithms were developed to analyze this data in context of the metabolic model, yielding flux distributions for wild-type and several engineered strains of M. extorquens. These fluxes were compared to those predicted by model simulation alone, and also integrated with microarray data to give an improved understanding of the metabolic physiology of this organism.

  2. Biogenic volatile organic compound and respiratory CO2 emissions after 13C-labeling: online tracing of C translocation dynamics in poplar plants.

    Andrea Ghirardo

    Full Text Available BACKGROUND: Globally plants are the primary sink of atmospheric CO(2, but are also the major contributor of a large spectrum of atmospheric reactive hydrocarbons such as terpenes (e.g. isoprene and other biogenic volatile organic compounds (BVOC. The prediction of plant carbon (C uptake and atmospheric oxidation capacity are crucial to define the trajectory and consequences of global environmental changes. To achieve this, the biosynthesis of BVOC and the dynamics of C allocation and translocation in both plants and ecosystems are important. METHODOLOGY: We combined tunable diode laser absorption spectrometry (TDLAS and proton transfer reaction mass spectrometry (PTR-MS for studying isoprene biosynthesis and following C fluxes within grey poplar (Populus x canescens saplings. This was achieved by feeding either (13CO(2 to leaves or (13C-glucose to shoots via xylem uptake. The translocation of (13CO(2 from the source to other plant parts could be traced by (13C-labeled isoprene and respiratory (13CO(2 emission. PRINCIPAL FINDING: In intact plants, assimilated (13CO(2 was rapidly translocated via the phloem to the roots within 1 hour, with an average phloem transport velocity of 20.3±2.5 cm h(-1. (13C label was stored in the roots and partially reallocated to the plants' apical part one day after labeling, particularly in the absence of photosynthesis. The daily C loss as BVOC ranged between 1.6% in mature leaves and 7.0% in young leaves. Non-isoprene BVOC accounted under light conditions for half of the BVOC C loss in young leaves and one-third in mature leaves. The C loss as isoprene originated mainly (76-78% from recently fixed CO(2, to a minor extent from xylem-transported sugars (7-11% and from photosynthetic intermediates with slower turnover rates (8-11%. CONCLUSION: We quantified the plants' C loss as respiratory CO(2 and BVOC emissions, allowing in tandem with metabolic analysis to deepen our understanding of ecosystem C flux.

  3. Biosynthesis and identification of 13C-labeled starch

    Biosynthesis of 13C-labeled starch was examined by using a small-scale apparatus. Tobacco leaves were placed in the cylindric photosynthesis chamber (14φx50 cm). After preincubation for 30 h in the dark, incubation with 13C-labeled CO2 was carried out for 48 h under irradiation with fluorescent lights. Labeled starch was extracted from the leaves and was purified. About 500 mg of 13C-labeled starch can be obtained from 50 g of the leaves. The 13C-abundance of the starch formed by the incubation was determined to be 82.0-92.0 atom % by mass spectrometry. (author)

  4. Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids

    You, Le; Page, Lawrence; Feng, Xueyang; Berla, Bert; Pakrasi, Himadri B; Yinjie J. Tang

    2012-01-01

    Microbes have complex metabolic pathways that can be investigated using biochemistry and functional genomics methods. One important technique to examine cell central metabolism and discover new enzymes is 13C-assisted metabolism analysis 1. This technique is based on isotopic labeling, whereby microbes are fed with a 13C labeled substrates. By tracing the atom transition paths between metabolites in the biochemical network, we can determine functional pathways and discover new ...

  5. Synthesis of ring-13C-labelled and ring-demethylated retinals

    Efficient synthetic schemes are described for the preparation of the required mono- and di-13C labelled retinals based on simple 13C labelled starting materials. Results from solid-state 13C-NMR spectroscopic studies of the various ring-13C labelled bacteriorhodopsins and rhodopsins are discussed. 404 refs.; 74 figs.; 16 tabs

  6. Synthesis of 13C-labelled lactose for metabolic studies in subjects with gastrointestinal disorders

    The long-range goals included development of a 13C-labelled lactose method for measuring lactose malabsorption in patients with diarrhea. The short-term goals included assembling a nuclear magnetic resonance system and a computer system for spectra analysis. The latter results are the subject of the report. (author)

  7. A Method to Constrain Genome-Scale Models with 13C Labeling Data.

    Héctor García Martín

    2015-09-01

    Full Text Available Current limitations in quantitatively predicting biological behavior hinder our efforts to engineer biological systems to produce biofuels and other desired chemicals. Here, we present a new method for calculating metabolic fluxes, key targets in metabolic engineering, that incorporates data from 13C labeling experiments and genome-scale models. The data from 13C labeling experiments provide strong flux constraints that eliminate the need to assume an evolutionary optimization principle such as the growth rate optimization assumption used in Flux Balance Analysis (FBA. This effective constraining is achieved by making the simple but biologically relevant assumption that flux flows from core to peripheral metabolism and does not flow back. The new method is significantly more robust than FBA with respect to errors in genome-scale model reconstruction. Furthermore, it can provide a comprehensive picture of metabolite balancing and predictions for unmeasured extracellular fluxes as constrained by 13C labeling data. A comparison shows that the results of this new method are similar to those found through 13C Metabolic Flux Analysis (13C MFA for central carbon metabolism but, additionally, it provides flux estimates for peripheral metabolism. The extra validation gained by matching 48 relative labeling measurements is used to identify where and why several existing COnstraint Based Reconstruction and Analysis (COBRA flux prediction algorithms fail. We demonstrate how to use this knowledge to refine these methods and improve their predictive capabilities. This method provides a reliable base upon which to improve the design of biological systems.

  8. Respiration of 13C-Labeled Substrates Added to Soil in the Field and Subsequent 16S rRNA Gene Analysis of 13C-Labeled Soil DNA

    Padmanabhan, P; Padmanabhan, S.; DeRito, C.; Gray, A; Gannon, D.; Snape, J. R.; Tsai, C. S.; Park, W.; Jeon, C.; Madsen, E.L.

    2003-01-01

    Our goal was to develop a field soil biodegradation assay using 13C-labeled compounds and identify the active microorganisms by analyzing 16S rRNA genes in soil-derived 13C-labeled DNA. Our biodegradation approach sought to minimize microbiological artifacts caused by physical and/or nutritional disturbance of soil associated with sampling and laboratory incubation. The new field-based assay involved the release of 13C-labeled compounds (glucose, phenol, caffeine, and naphthalene) to soil plo...

  9. Solid-state NMR determination of sugar ring pucker in (13)C-labeled 2'-deoxynucleosides.

    van Dam, Lorens; Ouwerkerk, Niels; Brinkmann, Andreas; Raap, Jan; Levitt, Malcolm H.

    2002-01-01

    The H3'-C3'-C4'-H4' torsional angles of two microcrystalline 2'-deoxynucleosides, thymidine and 2'-deoxycytidine.HCl, doubly (13)C-labeled at the C3' and C4' positions of the sugar ring, have been measured by solid-state magic-angle-spinning nuclear magnetic resonance (NMR). A double-quantum heteronuclear local field experiment with frequency-switched Lee-Goldberg homonuclear decoupling was used. The H3'-C3'-C4'-H4' torsional angles were obtained by comparing the experimental curves with nume...

  10. Biosynthetically directed fractional 13C labeling facilitates identification of Phe and Tyr aromatic signals in proteins

    Analysis of 2D [13C,1H]-HSQC spectra of biosynthetic fractionally 13C labeled proteins is a reliable, straightforward means to obtain stereospecific assignments of Val and Leu methyl sites in proteins. Herein we show that the same fractionally labeled protein sample facilitates observation and identification of Phe and Tyr aromatic signals. This is the case, in part, because the fractional 13C labeling yields aromatic rings in which some of the 13C-13C J-couplings, present in uniformly labeled samples, are absent. Also, the number of homonuclear J-coupling partners differs for the δ-, ε- and ζ-carbons. This enabled us to vary their signal intensities in distinctly different ways by appropriately setting the 13C constant-time period in 2D [13C,1H]-HSQC spectra. We illustrate the application of this approach to an 18 kDa protein, c-VIAF, a modulator of apoptosis. In addition, we show that cancellation of the aromatic 13C CSA and 13C-1H dipolar interactions can be fruitfully utilized in the case of the fractionally labeled sample to obtain high resolution 13C constant-time spectra with good sensitivity

  11. Correction factors for 13C-labelled substrate oxidation at whole-body and muscle level

    Van Hall, Gerrit

    1999-01-01

    The oxidation of fatty acids, carbohydrates and amino acids can be measured by quantifying the rate of excretion of labelled CO2 following administration of 14C- or 13C-labelled substrates at whole-body and tissue level. However, there is a theoretical need to correct the oxidation rates for the...... proportion of labelled CO2 that is produced via oxidation but not excreted. Furthermore, depending on the substrate and position of the C label(s), there may also be a need to correct for labelled C from the metabolized substrate that does not appear as CO2, but rather becomes temporarily fixed in other...... metabolites. The bicarbonate correction factor is used to correct for the labelled CO2 not excreted. Recently, an acetate correction factor has been proposed for the simultaneous correction of CO2 not excreted and label fixed in other metabolites via isotopic exchange reactions, mainly in the tricarboxylic...

  12. Increased resolution of aromatic cross peaks using alternate {sup 13}C labeling and TROSY

    Milbradt, Alexander G. [AstraZeneca Discovery Sciences, Structure and Biophysics UK (United Kingdom); Arthanari, Haribabu [Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology (United States); Takeuchi, Koh [National Institute of Advanced Industrial Science and Technology, Biomedicinal Information Research Center and Molecular Profiling Research Center for Drug Discovery (Japan); Boeszoermenyi, Andras; Hagn, Franz; Wagner, Gerhard, E-mail: gerhard-wagner@hms.harvard.edu [Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology (United States)

    2015-07-15

    For typical globular proteins, contacts involving aromatic side chains would constitute the largest number of distance constraints that could be used to define the structure of proteins and protein complexes based on NOE contacts. However, the {sup 1}H NMR signals of aromatic side chains are often heavily overlapped, which hampers extensive use of aromatic NOE cross peaks. Some of this overlap can be overcome by recording {sup 13}C-dispersed NOESY spectra. However, the resolution in the carbon dimension is rather low due to the narrow dispersion of the carbon signals, large one-bond carbon–carbon (C–C) couplings, and line broadening due to chemical shift anisotropy (CSA). Although it has been noted that the CSA of aromatic carbons could be used in TROSY experiments for enhancing resolution, this has not been used much in practice because of complications arising from large aromatic one-bond C–C couplings, and 3D or 4D carbon dispersed NOESY are typically recorded at low resolution hampering straightforward peak assignments. Here we show that the aromatic TROSY effect can optimally be used when employing alternate {sup 13}C labeling using 2-{sup 13}C glycerol, 2-{sup 13}C pyruvate, or 3-{sup 13}C pyruvate as the carbon source. With the elimination of the strong one-bond C–C coupling, the TROSY effect can easily be exploited. We show that {sup 1}H–{sup 13}C TROSY spectra of alternately {sup 13}C labeled samples can be recorded at high resolution, and we employ 3D NOESY aromatic-TROSY spectra to obtain valuable intramolecular and intermolecular cross peaks on a protein complex.

  13. Synthesis and applications of selectively {sup 13}C-labeled RNA

    SantaLucia, J. Jr.; Shen, L.X.; Lewis, H.; Cai, Z.; Tinoci, I. Jr. [Univ. of California, Berkeley, CA (United States)

    1994-12-01

    Spectral overlap is a substantial problem in NMR studies of RNA molecules >30 nucleotides. To overcome this difficulty, we synthesized selectively {sup 13}C-labeled RNAs and adapted several isotope-edited two- and three-dimensional NMR experiments originally developed for protein studies. We optimized protocols for synthesis of multi-gram quantities of CTP, UTp, ATP, and GTP using a combination of synthetic organic and enzymatic methods. Uracil is prepared in 40 to 50% yield from {sup 13}C-cyanide in two steps. Using acetyl- tribenzoyl-ribose and standard chemistry uracil is then attached to the sugar (90% yield). The tribenzoyl-uridine intermediate is converted into uridine or cytidine quantitatively, depending on the deblocking protocol. Labeled purines are synthesized using simple pyrimidine precursors and reacting with {sup 13}C-formic acid (80% yield). Purine nucleosides are then synthesized using uridine phosphorylase and purine nucleoside phosphorylase. The nucleosides were converted to NMPs by treatment with POC1{sub 3} in triethylphosphate. We converted NMPs to NTPs by standard enzymatic methods. Selectively labeled RNAs were synthesized by run-off transcription using {sup 13}C-labeled NTPs. Several different strategies help solve over-lap problems in larger RNAs. Isotope-edited two-dimensional NMR experiments such as {omega}1-1/2 X-filtered NOESY simplify NMR spectra by dividing the normal NOESY spectrum into two subspectra-one involving NOEs from protons bound to {sup 12}C and one from protons bound to {sup 13}C. For example, we labeled A and U residues of a 34-nucleotide pseudoknot, and the {sup 12}C subspectrum of the 1/2 X-filtered NOESY contained NOEs only from G and C residues (along with adenine 2H); the {sup 13}C subspectrum contained NOEs only from A and U residues. Each subspectrum has less overlap than the NOESY of an unlabeled sample; the editing strategy allows each resonance to be identified by residue type (A, C, G, or U).

  14. Mineralisation, leaching and stabilisation of 13C-labelled leaf and twig litter in a beech forest soil

    F. Hagedorn

    2011-02-01

    Full Text Available Very few field studies have quantified the different pathways of C loss from decomposing litter even though this is essential to better understand long-term dynamics of C stocks in soils. Using 13C-labelled leaf (isotope ratio (δ13C = −40.8‰ and twig litter (δ13C = −38.4‰, we tracked down the litter-derived C in the soil respiration, in the dissolved organic C (DOC and in the soil organic matter of a beech forest in the Swiss Jura. After one year of decomposition, mass loss in the litter layer was almost twice as great for leaves as it was for twigs (75% vs. 40%. This difference was not the result of a slow mineralisation of the woody litter, but primarily of the only slight incorporation of twig-derived C into mineral soils. The C mineralisation rates of the twig litter were only slightly lower than those of the leaf litter (10–35%, in particular after the loss of the readily available litter fraction. However, the leaching of DOC from twigs amounted only to half of that from leaves. Tracing the litter-derived DOC showed that DOC from both litter types was mostly retained (88–96% and stabilised in the top centimetres of the mineral soil. In the soil organic C at 0–2 cm depth, we recovered 8% of the initial leaf C, but only 4% of the twig C. Moreover, the 13C mass balance suggested that a substantial fraction of the leaf material (~30% was transported via soil fauna to soil depths below 2 cm, while the twig litter mainly decomposed in situ on the soil surface, probably due to its rigid structure and low nutritional value. In summary, our study shows that decaying twigs are rapidly mineralised, but seem to be clearly less important for the C storage in this beech forest soils than leaf litter.

  15. Uptake of phytodetritus by meiobenthos using 13C labelled diatoms and Phaeocystis in two contrasting sediments from the North Sea

    Franco, M.A.; Soetaert, K.E.R.; Costa, M.J.; Vincx, M.; Vanaverbeke, J.

    2008-01-01

    Meiobenthic uptake of 13C labelled diatom Skeletonema costatum and Prymnesiophyte Phaeocystis was investigated in permeable and fine grained depositional sediments from the Southern Bight of the North Sea at different sediment horizons. Both the diatom and Phaeocystis–derived organic matter (OM) cas

  16. Perdeuteration and methyl-selective {sup 1}H, {sup 13}C-labeling by using a Kluyveromyces lactis expression system

    Miyazawa-Onami, Mayumi [Japan Biological Informatics Consortium, Research and Development Department (Japan); Takeuchi, Koh [National Institute of Advanced Industrial Science and Technology, Biomedicinal Information Research Center (Japan); Takano, Toshiaki; Sugiki, Toshihiko [Japan Biological Informatics Consortium, Research and Development Department (Japan); Shimada, Ichio, E-mail: shimada@iw-nmr.f.u-tokyo.ac.jp; Takahashi, Hideo, E-mail: hid@tsurumi.yokohama-cu.ac.jp [National Institute of Advanced Industrial Science and Technology, Biomedicinal Information Research Center (Japan)

    2013-10-22

    The production of stable isotope-labeled proteins is critical in structural analyses of large molecular weight proteins using NMR. Although prokaryotic expression systems using Escherichia coli have been widely used for this purpose, yeast strains have also been useful for the expression of functional eukaryotic proteins. Recently, we reported a cost-effective stable isotope-labeled protein expression using the hemiascomycete yeast Kluyveromyces lactis (K. lactis), which allow us to express exogenous proteins at costs comparable to prokaryotic expression systems. Here, we report the successful production of highly deuterated (>90 %) protein in the K. lactis system. We also examined the methyl-selective {sup 1}H, {sup 13}C-labeling of Ile, Leu, and Val residues using commonly used amino acid precursors. The efficiency of {sup 1}H- {sup 13}C-incorporation varied significantly based on the amino acid. Although a high level of {sup 1}H-{sup 13}C-incorporation was observed for the Ile δ1 position, {sup 1}H, {sup 13}C-labeling rates of Val and Leu methyl groups were limited due to the mitochondrial localization of enzymes involved in amino acid biosynthesis and the lack of transporters for α-ketoisovalerate in the mitochondrial membrane. In line with this notion, the co-expression with branched-chain-amino-acid aminotransferase in the cytosol significantly improved the incorporation rates of amino acid precursors. Although it would be less cost-effective, addition of {sup 13}C-labeled valine can circumvent problems associated with precursors and achieve high level {sup 1}H, {sup 13}C-labeling of Val and Leu. Taken together, the K. lactis system would be a good alternative for expressing large eukaryotic proteins that need deuteration and/or the methyl-selective {sup 1}H, {sup 13}C-labeling for the sensitive detection of NMR resonances.

  17. IRMS detection of testosterone manipulated with 13C labeled standards in human urine by removing the labeled 13C

    Highlights: • 13C labeled testosterone can be used to adjust the isotope ratio of testosterone. • The novel testosterone cannot be detected by the regular IRMS method in doping test. • A method was explored to remove the labeled 13C. • The established method can be used to detect the manipulated testosterone. - Abstract: Isotope ratio mass spectrometry (IRMS) is applied to confirm testosterone (T) abuse by determining the carbon isotope ratios (δ13C value). However, 13C labeled standards can be used to control the δ13C value and produce manipulated T which cannot be detected by the current method. A method was explored to remove the 13C labeled atom at C-3 from the molecule of androsterone (Andro), the metabolite of T in urine, to produce the resultant (A-nor-5α-androstane-2,17-dione, ANAD). The difference in δ13C values between Andro and ANAD (Δδ13CAndro–ANAD, ‰) would change significantly in case manipulated T is abused. Twenty-one volunteers administered T manipulated with different 13C labeled standards. The collected urine samples were analyzed with the established method, and the maximum value of Δδ13CAndro–ANAD post ingestion ranged from 3.0‰ to 8.8‰. Based on the population reference, the cut-off value of Δδ13CAndro–ANAD for positive result was suggested as 1.2‰. The developed method could be used to detect T manipulated with 3-13C labeled standards

  18. Perdeuteration and methyl-selective 1H, 13C-labeling by using a Kluyveromyces lactis expression system

    The production of stable isotope-labeled proteins is critical in structural analyses of large molecular weight proteins using NMR. Although prokaryotic expression systems using Escherichia coli have been widely used for this purpose, yeast strains have also been useful for the expression of functional eukaryotic proteins. Recently, we reported a cost-effective stable isotope-labeled protein expression using the hemiascomycete yeast Kluyveromyces lactis (K. lactis), which allow us to express exogenous proteins at costs comparable to prokaryotic expression systems. Here, we report the successful production of highly deuterated (>90 %) protein in the K. lactis system. We also examined the methyl-selective 1H, 13C-labeling of Ile, Leu, and Val residues using commonly used amino acid precursors. The efficiency of 1H- 13C-incorporation varied significantly based on the amino acid. Although a high level of 1H-13C-incorporation was observed for the Ile δ1 position, 1H, 13C-labeling rates of Val and Leu methyl groups were limited due to the mitochondrial localization of enzymes involved in amino acid biosynthesis and the lack of transporters for α-ketoisovalerate in the mitochondrial membrane. In line with this notion, the co-expression with branched-chain-amino-acid aminotransferase in the cytosol significantly improved the incorporation rates of amino acid precursors. Although it would be less cost-effective, addition of 13C-labeled valine can circumvent problems associated with precursors and achieve high level 1H, 13C-labeling of Val and Leu. Taken together, the K. lactis system would be a good alternative for expressing large eukaryotic proteins that need deuteration and/or the methyl-selective 1H, 13C-labeling for the sensitive detection of NMR resonances

  19. Structure and Metabolic-Flow Analysis of Molecular Complexity in a (13) C-Labeled Tree by 2D and 3D NMR.

    Komatsu, Takanori; Ohishi, Risa; Shino, Amiu; Kikuchi, Jun

    2016-05-10

    Improved signal identification for biological small molecules (BSMs) in a mixture was demonstrated by using multidimensional NMR on samples from (13) C-enriched Rhododendron japonicum (59.5 atom%) cultivated in air containing (13) C-labeled carbon dioxide for 14 weeks. The resonance assignment of 386 carbon atoms and 380 hydrogen atoms in the mixture was achieved. 42 BSMs, including eight that were unlisted in the spectral databases, were identified. Comparisons between the experimental values and the (13) C chemical shift values calculated by density functional theory supported the identifications of unlisted BSMs. Tracing the (13) C/(12) C ratio by multidimensional NMR spectra revealed faster and slower turnover ratios of BSMs involved in central metabolism and those categorized as secondary metabolites, respectively. The identification of BSMs and subsequent flow analysis provided insight into the metabolic systems of the plant. PMID:27060701

  20. Combining position-specific 13C labeling with compound-specific isotope analysis: first steps towards soil fluxomics

    Dippold, Michaela; Kuzyakov, Yakov

    2015-04-01

    Understanding the soil organic matter (SOM) dynamics is one of the most important challenges in soil science. Transformation of low molecular weight organic substances (LMWOS) is a key step in biogeochemical cycles because 1) all high molecular substances pass this stage during their decomposition and 2) only LMWOS will be taken up by microorganisms. Previous studies on LMWOS were focused on determining net fluxes through the LMWOS pool, but they rarely identified transformations. As LMWOS are the preferred C and energy source for microorganisms, the transformations of LMWOS are dominated by biochemical pathways of the soil microorganisms. Thus, understanding fluxes and transformations in soils requires a detailed knowledge on the biochemical pathways and its controlling factors. Tracing C fate in soil by isotopes became on of the most applied and promising biogeochemistry tools. Up to now, studies on LMWOS were nearly exclusively based on uniformly labeled organic substances i.e. all C atoms in the molecules were labeled with 13C or 14C. However, this classical approach did not allow the differentiation between use of intact initial substances in any process, or whether they were transformed to metabolites. The novel tool of position-specific labeling enables to trace molecule atoms separately and thus to determine the cleavage of molecules - a prerequisite for metabolic tracing. Position-specific labeling of LMWOS and quantification of 13CO2 and 13C in bulk soil enabled following the basic metabolic pathways of soil microorganisms. However, only the combination of position-specific 13C labeling with compound-specific isotope analysis of microbial biomarkers and metabolites allowed 1) tracing specific anabolic pathways in diverse microbial communities in soils and 2) identification of specific pathways of individual functional microbial groups. So, these are the prerequisites for soil fluxomics. Our studies combining position-specific labeled glucose with amino

  1. Economical Synthesis of 13C-Labeled Opiates, Cocaine Derivatives and Selected Urinary Metabolites by Derivatization of the Natural Products

    Morten Karlsen; Huiling Liu; Jon Eigill Johansen; Bård Helge Hoff

    2015-01-01

    The illegal use of opiates and cocaine is a challenge world-wide, but some derivatives are also valuable pharmaceuticals. Reference samples of the active ingredients and their metabolites are needed both for controlling administration in the clinic and to detect drugs of abuse. Especially, 13C-labeled compounds are useful for identification and quantification purposes by mass spectroscopic techniques, potentially increasing accuracy by minimizing ion alteration/suppression effects. Thus, the ...

  2. Estimating High-Affinity Methanotrophic Bacterial Biomass, Growth, and Turnover in Soil by Phospholipid Fatty Acid 13C Labeling

    Maxfield, P. J.; E. R. C. Hornibrook; Evershed, R. P.

    2006-01-01

    A time series phospholipid fatty acid (PLFA) 13C-labeling study was undertaken to determine methanotrophic taxon, calculate methanotrophic biomass, and assess carbon recycling in an upland brown earth soil from Bronydd Mawr (Wales, United Kingdom). Laboratory incubations of soils were performed at ambient CH4 concentrations using synthetic air containing 2 parts per million of volume of 13CH4. Flowthrough chambers maintained a stable CH4 concentration throughout the 11-week incubation. Soils ...

  3. The fate of (13)C-labelled and non-labelled inulin predisposed to large bowel fermentation in rats.

    Butts, Christine A; Paturi, Gunaranjan; Tavendale, Michael H; Hedderley, Duncan; Stoklosinski, Halina M; Herath, Thanuja D; Rosendale, Douglas; Roy, Nicole C; Monro, John A; Ansell, Juliet

    2016-04-20

    The fate of stable-isotope (13)C labelled and non-labelled inulin catabolism by the gut microbiota was assessed in a healthy rat model. Sprague-Dawley male rats were randomly assigned to diets containing either cellulose or inulin, and were fed these diets for 3 days. On day (d) 4, rats allocated to the inulin diet received (13)C-labelled inulin. The rats were then fed the respective non-labelled diets (cellulose or inulin) until sampling (d4, d5, d6, d7, d10 and d11). Post feeding of (13)C-labelled substrate, breath analysis showed that (13)C-inulin cleared from the host within a period of 36 hours. Faecal (13)C demonstrated the clearance of inulin from gut with a (13)C excess reaching maximum at 24 hours (d5) and then declining gradually. There were greater variations in caecal organic acid concentrations from d4 to d6, with higher concentrations of acetic, butyric and propionic acids observed in the rats fed inulin compared to those fed cellulose. Inulin influenced caecal microbial glycosidase activity, increased colon crypt depth, and decreased the faecal output and polysaccharide content compared to the cellulose diet. In summary, the presence of inulin in the diet positively influenced large bowel microbial fermentation. PMID:26778667

  4. Use of 13C-Labeled Substrates to Determine Relative Methane Production Rates in Hypersaline Microbial Communities

    Kelley, C. A.; Bebout, B.; Chanton, J.

    2015-12-01

    Rates and pathways of methane production were determined from photosynthetic soft microbial mats and gypsum-encrusted endoevaporites collected in hypersaline environments from California, Mexico and Chile, as well as an organic-rich mud from a pond in the El Tatio volcanic fields, Chile. Samples (mud, homogenized soft mats and endoevaporites) were incubated anaerobically with deoxygenated site water, and the increase in methane concentration through time in the headspaces of the incubation vials was used to determine methane production rates. To ascertain the substrates used by the methanogens, 13C-labeled methylamines, methanol, dimethylsulfide, acetate or bicarbonate were added to the incubations (one substrate per vial) and the stable isotopic composition of the resulting methane was measured. The vials amended with 13C-labeled methylamines produced the most 13C-enriched methane, generally followed by the 13C-labeled methanol-amended vials. The stable isotope data and the methane production rates were used to determine first order rate constants for each of the substrates at each of the sites. Estimates of individual substrate use revealed that the methylamines produced 55 to 92% of the methane generated, while methanol was responsible for another 8 to 40%.

  5. Utilization of low molecular weight organics by soil microorganisms: combination of 13C-labelling with PLFA analysis

    Gunina, Anna; Dippold, Michaela; Kuzyakov, Yakov

    2014-05-01

    Microbial metabolisation is the main transformation pathway of low molecular weight organic substances (LMWOS), but detailed knowledge concerning the fate of LMWOS in soils is strongly limited. Considering that various LMWOS classes enter biochemical cycles at different steps, we hypothesise that the percentage of their LMWOS-Carbon (C) used for microbial biomass (MB) production and consequently medium-term stabilisation in soil is different. We traced the three main groups of LMWOS: amino acids, sugars and carboxylic acids, by uniformly labelled 13C-alanine, -glutamate, -glucose, -ribose, -acetate and -palmitate. Incorporation of 13C from these LMWOS into MB (fumigation-extraction method) and into phospholipid fatty acids (PLFAs) (Bligh-Dyer extraction, purification and GC-C-IRMS measurement) was investigated under field conditions 3 d and 10 d after LMWOS application. The activity of microbial utilization of LMWOS for cell membrane construction was estimated by replacement of PLFA-C with 13C. Decomposition of LMWOS-C comprised 20-65% of the total label, whereas incorporation of 13C into MB amounted to 20-50% of initially applied 13C on day three and was reduced to 5-30% on day 10. Incorporation of 13C-labelled LMWOS into MB followed the trend sugars > carboxylic acids > amino acids. Differences in microbial utilisation between LMWOS were observed mainly at day 10. Thus, instead of initial rapid uptake, further metabolism within microbial cells accounts for the individual fate of C from different LMWOS in soils. Incorporation of 13C from each LMWOS into each PLFA occurred, which reflects the ubiquitous ability of all functional microbial groups for LMWOS utilization. The preferential incorporation of palmitate can be attributed to its role as a direct precursor for many fatty acids (FAs) and PLFA formation. Higher incorporation of alanine and glucose compared to glutamate, ribose and acetate reflect the preferential use of glycolysis-derived substances in the FAs

  6. Economical synthesis of 13C-labeled opiates, cocaine derivatives and selected urinary metabolites by derivatization of the natural products.

    Karlsen, Morten; Liu, Huiling; Johansen, Jon Eigill; Hoff, Bård Helge

    2015-01-01

    The illegal use of opiates and cocaine is a challenge world-wide, but some derivatives are also valuable pharmaceuticals. Reference samples of the active ingredients and their metabolites are needed both for controlling administration in the clinic and to detect drugs of abuse. Especially, (13)C-labeled compounds are useful for identification and quantification purposes by mass spectroscopic techniques, potentially increasing accuracy by minimizing ion alteration/suppression effects. Thus, the synthesis of [acetyl-(13)C4]heroin, [acetyl-(13)C4-methyl-(13)C]heroin, [acetyl-(13)C2-methyl-(13)C]6-acetylmorphine, [N-methyl-(13)C-O-metyl-(13)C]codeine and phenyl-(13)C6-labeled derivatives of cocaine, benzoylecgonine, norcocaine and cocaethylene was undertaken to provide such reference materials. The synthetic work has focused on identifying (13)C atom-efficient routes towards these derivatives. Therefore, the (13)C-labeled opiates and cocaine derivatives were made from the corresponding natural products. PMID:25816077

  7. Economical Synthesis of 13C-Labeled Opiates, Cocaine Derivatives and Selected Urinary Metabolites by Derivatization of the Natural Products

    Morten Karlsen

    2015-03-01

    Full Text Available The illegal use of opiates and cocaine is a challenge world-wide, but some derivatives are also valuable pharmaceuticals. Reference samples of the active ingredients and their metabolites are needed both for controlling administration in the clinic and to detect drugs of abuse. Especially, 13C-labeled compounds are useful for identification and quantification purposes by mass spectroscopic techniques, potentially increasing accuracy by minimizing ion alteration/suppression effects. Thus, the synthesis of [acetyl-13C4]heroin, [acetyl-13C4-methyl-13C]heroin, [acetyl-13C2-methyl-13C]6-acetylmorphine, [N-methyl-13C-O-metyl-13C]codeine and phenyl-13C6-labeled derivatives of cocaine, benzoylecgonine, norcocaine and cocaethylene was undertaken to provide such reference materials. The synthetic work has focused on identifying 13C atom-efficient routes towards these derivatives. Therefore, the 13C-labeled opiates and cocaine derivatives were made from the corresponding natural products.

  8. The effect of biochar amendment on the soil microbial community - PLFA analyses and 13C labeling results

    Watzinger, A.; Feichtmair, S.; Rempt, F.; Anders, E.; Wimmer, B.; Kitzler, B.; Zechmeister-Boltenstern, S.; Horacek, M.; Zehetner, F.; Kloss, S.; Richoz, S.; Soja, G.

    2012-04-01

    The effects of biochar amendment on plant growth and on the chemical / physical soil characteristics are well explored but only few studies have investigated the impact on soil microorganisms. The response of the soil microbial community to biochar amendment was investigated by phospholipid fatty acid (PLFA) analysis in (i) a large scale pot experiment, (ii) a small scale pot experiment using 13C labeled biochar and (iii) an incubation study using 13C labeled biochar. In the large scale pot experiment, three different agricultural soils from Austria (Planosol, Cambisol, Chernozem) and four different types of biochar were investigated. In total, 25 treatments with 5 replicates each were set up and monitored over a year. The results from the pot experiments showed no significant influence of biochar amendment on the total microbial biomass in the first 100 days after biochar addition. However, discriminant analysis showed a distinction of biochar and control soils as well as a strong effect of the pyrolysis temperature on the microbial composition. The effect of biochar was dependent on the type of soil. In the Planosol, some PLFAs were affected positively, especially when adding biochar with a low pyrolysis temperature, in the first month. In the long term, microbial community composition altered. Growth of fungi and gram negative bacteria was enhanced. In the Chernozem, PLFAs from various microbial groups decreased in the long term. Variability in the incubation study was low. Consequently, many PLFAs were significantly affected by biochar amendment. Again, in the Planosol, gram negative bacteria, actinomycetes and, after 2 weeks, gram positive bacteria increased under biochar amendment whereas in the chernozem total microbial biomass and gram positive bacteria were negatively affected in the long term. The 13C labeling studies confirmed the low degradability of the biochar, i.e. no alteration of the content and the δ13C in the soil organic matter within 100 days

  9. Determination of the Orientation and Dynamics of Ergosterol in Model Membranes Using Uniform 13C Labeling and Dynamically Averaged 13C Chemical Shift Anisotropies as Experimental Restraints

    Soubias, O.; Jolibois, F.; Massou, S.; Milon, A.; Réat, V.

    2005-01-01

    A new strategy was established to determine the average orientation and dynamics of ergosterol in dimyristoylphosphatidylcholine model membranes. It is based on the analysis of chemical shift anisotropies (CSAs) averaged by the molecular dynamics. Static 13C CSA tensors were computed by quantum chemistry, using the gauge-including atomic-orbital approach within Hartree-Fock theory. Uniformly 13C-labeled ergosterol was purified from Pichia pastoris cells grown on labeled methanol. After reconstitution into dimyristoylphosphatidylcholine lipids, the complete 1H and 13C assignment of ergosterol's resonances was performed using a combination of magic-angle spinning two-dimensional experiments. Dynamically averaged CSAs were determined by standard side-band intensity analysis for isolated 13C resonances (C3 and ethylenic carbons) and by off-magic-angle spinning experiments for other carbons. A set of 18 constraints was thus obtained, from which the sterol's molecular order parameter and average orientation could be precisely defined. The validity of using computed CSAs in this strategy was verified on cholesterol model systems. This new method allowed us to quantify ergosterol's dynamics at three molar ratios: 16 mol % (Ld phase), 30 mol % (Lo phase), and 23 mol % (mixed phases). Contrary to cholesterol, ergosterol's molecular diffusion axis makes an important angle (14°) with the inertial axis of the rigid four-ring system. PMID:15923221

  10. Synthesis of 13C-labeled vitamin E and interaction between vitamin E and phospholipid in liposome

    Vitamin E with a 13C-labeled isoprenoid side chain, [4'a-13C], [6'-13C], [8'a-13C] and [12'a and 13'-13C]α-tocopherols were synthesized. These compounds were incorporated into three kinds of lecithin liposomes from dipalmitoyl phosphatidyl cholin, egg lecithin and rat liver lecithin, of which arachidonic acid contents are 0, 2.6 and 19.0%, respectively. T1 values, which were measured by NMR for the labeled carbons, indicate that the segmental motion tends to increase with the increase of the distance from the chroman ring. This tendency is not affected with the arachidonic acid contents of phospholipids. This result can not be explained by Lucy's hypothesis. 1 figure; 1 table

  11. Comprehensive discovery of 13C labeled metabolites in the bacterium Methylobacterium extorquens AM1 using gas chromatography-mass spectrometry.

    Yang, Song; Hoggard, Jamin C; Lidstrom, Mary E; Synovec, Robert E

    2013-11-22

    Herein, we report the identification of isotopically labeled metabolite peaks (or the lack of labeling) between sets of GC-MS data from Methylobacterium extorquens AM1. M. extorquens AM1 is one of the best-characterized model organisms for the study of C1 metabolism in methylotrophic bacteria, a diverse group of microbes that can use reduced one-carbon (C1) sources, such as methanol and methane as a sole source for both energy generation and carbon assimilation. Application of a match value (MV) based metric was used to rank the metabolite peaks in the data from those exhibiting the most mass spectral indications of labeling, to those not exhibiting any indications of labeling. The MV-based ranking corresponded well with analyst interpretation of the mass spectra. The MV-based method was initially demonstrated and validated using a mixture of 21 standards with data sets generated for mixtures at natural abundance, a mixture with 6 of the compounds labeled, and a 1:1 mixture of the natural abundance and labeled mixtures. Experimental data from TMS-derivatized extracts from the bacterium M. extorquens AM1 grown with natural abundance or (13)C-labeled methanol as the carbon source were analyzed. Of 131 peaks considered for the analysis of M. extorquens AM1, the 40 peaks ranked highest for indications of (13)C labeling were all found to be labeled, while those peaks ranked lower progressed from peaks for which labeling was uncertain, to a larger number of peaks that were clearly not labeled. The list of peaks determined to be labeled forms a library of compounds that are known to be labeled following the methanol metabolic pathway in M. extorquens AM1 that can be further investigated in future work, e.g. fluxomic studies. PMID:24007683

  12. A comprehensive metabolic profile of cultured astrocytes using isotopic transient metabolic flux analysis and 13C-labeled glucose

    Ursula Sonnewald

    2011-09-01

    Full Text Available Metabolic models have been used to elucidate important aspects of brain metabolism in recent years. This work applies for the first time the concept of isotopic transient 13C metabolic flux analysis (MFA to estimate intracellular fluxes of cultured astrocytes. This methodology comprehensively explores the information provided by 13C labeling time-courses of intracellular metabolites after administration of a 13C labeled substrate. Cells were incubated with medium containing [1-13C]glucose for 24 h and samples of cell supernatant and extracts collected at different time-points were then analyzed by mass spectrometry and/or HPLC. Metabolic fluxes were estimated by fitting a carbon labeling network model to isotopomer profiles experimentally determined. Both the fast isotopic equilibrium of glycolytic metabolite pools and the slow labeling dynamics of TCA cycle intermediates are described well by the model. The large pools of glutamate and aspartate which are linked to the TCA cycle via reversible aminotransferase reactions are likely to be responsible for the observed delay in equilibration of TCA cycle intermediates. Furthermore, it was estimated that 11% of the glucose taken up by astrocytes was diverted to the pentose phosphate pathway. In addition, considerable fluxes through pyruvate carboxylase (PC (PC/pyruvate dehydrogenase (PDH ratio = 0.5, malic enzyme (5% of the total pyruvate production and catabolism of branched-chained amino acids (contributing with ~40% to total acetyl-CoA produced confirmed the significance of these pathways to astrocytic metabolism. Consistent with the need of maintaining cytosolic redox potential, the fluxes through the malate-aspartate shuttle and the PDH pathway were comparable. Finally, the estimated glutamate/α-ketoglutarate exchange rate (~0.7 µmol.mg prot-1.h-1 was similar to the TCA cycle flux. In conclusion, this work demonstrates the potential of isotopic transient MFA for a comprehensive analysis of

  13. A hybrid strategy for the preparation of 13C-labeled high-mannose-type oligosaccharides with terminal glucosylation for NMR study

    Stable isotopic labeling dramatically facilitates NMR studies of oligosaccharides. We previously established a method for overexpressing homogeneous high-mannose-type oligosaccharides with metabolic 13C labeling using genetically engineered yeast cells. To extend the applicability of this methodology, we combined it with chemoenzymatic synthesis using a specific glucosyl transferase. Our hybrid approach has enabled the production of a uniformly and selectively 13C-labeled dodecasaccharide with terminal glucosylation, a signal recognized by molecular chaperones, providing useful NMR tools for detailed conformational analyses. (author)

  14. High resolution 4D HPCH experiment for sequential assignment of {sup 13}C-labeled RNAs via phosphodiester backbone

    Saxena, Saurabh; Stanek, Jan [University of Warsaw, Faculty of Chemistry, Biological and Chemical Research Centre (Poland); Cevec, Mirko; Plavec, Janez [National Institute of Chemistry, Slovenian NMR Centre (Slovenia); Koźmiński, Wiktor, E-mail: kozmin@chem.uw.edu.pl [University of Warsaw, Faculty of Chemistry, Biological and Chemical Research Centre (Poland)

    2015-11-15

    The three-dimensional structure determination of RNAs by NMR spectroscopy requires sequential resonance assignment, often hampered by assignment ambiguities and limited dispersion of {sup 1}H and {sup 13}C chemical shifts, especially of C4′/H4′. Here we present a novel through-bond 4D HPCH NMR experiment involving phosphate backbone where C4′–H4′ correlations are resolved along the {sup 1}H3′–{sup 31}P spectral planes. The experiment provides high peak resolution and effectively removes ambiguities encountered during assignments. Enhanced peak dispersion is provided by the inclusion of additional {sup 31}P and {sup 1}H3′ dimensions and constant-time evolution of chemical shifts. High spectral resolution is obtained by using non-uniform sampling in three indirect dimensions. The experiment fully utilizes the isotopic {sup 13}C-labeling with evolution of C4′ carbons. Band selective {sup 13}C inversion pulses are used to achieve selectivity and prevent signal dephasing due to the C4′–C3′ and C4′–C5′ homonuclear couplings. Multiple quantum line narrowing is employed to minimize sensitivity loses. The 4D HPCH experiment is verified and successfully applied to a non-coding 34-nt RNA consisting typical structure elements and a 14-nt RNA hairpin capped by cUUCGg tetraloop.

  15. High resolution 4D HPCH experiment for sequential assignment of 13C-labeled RNAs via phosphodiester backbone

    The three-dimensional structure determination of RNAs by NMR spectroscopy requires sequential resonance assignment, often hampered by assignment ambiguities and limited dispersion of 1H and 13C chemical shifts, especially of C4′/H4′. Here we present a novel through-bond 4D HPCH NMR experiment involving phosphate backbone where C4′–H4′ correlations are resolved along the 1H3′–31P spectral planes. The experiment provides high peak resolution and effectively removes ambiguities encountered during assignments. Enhanced peak dispersion is provided by the inclusion of additional 31P and 1H3′ dimensions and constant-time evolution of chemical shifts. High spectral resolution is obtained by using non-uniform sampling in three indirect dimensions. The experiment fully utilizes the isotopic 13C-labeling with evolution of C4′ carbons. Band selective 13C inversion pulses are used to achieve selectivity and prevent signal dephasing due to the C4′–C3′ and C4′–C5′ homonuclear couplings. Multiple quantum line narrowing is employed to minimize sensitivity loses. The 4D HPCH experiment is verified and successfully applied to a non-coding 34-nt RNA consisting typical structure elements and a 14-nt RNA hairpin capped by cUUCGg tetraloop

  16. IRMS detection of testosterone manipulated with {sup 13}C labeled standards in human urine by removing the labeled {sup 13}C

    Wang, Jingzhu, E-mail: wangjingzhu@chinada.cn [National Anti-Doping Laboratory, China Anti-Doping Agency, Beijing (China); Yang, Rui [Sport Science College, Beijing Sport University Beijing, Beijing (China); Yang, Wenning [School of Pharmacy, Beijing University of Chinese Medicine, Beijing (China); Liu, Xin; Xing, Yanyi; Xu, Youxuan [National Anti-Doping Laboratory, China Anti-Doping Agency, Beijing (China)

    2014-12-10

    Highlights: • {sup 13}C labeled testosterone can be used to adjust the isotope ratio of testosterone. • The novel testosterone cannot be detected by the regular IRMS method in doping test. • A method was explored to remove the labeled {sup 13}C. • The established method can be used to detect the manipulated testosterone. - Abstract: Isotope ratio mass spectrometry (IRMS) is applied to confirm testosterone (T) abuse by determining the carbon isotope ratios (δ{sup 13}C value). However, {sup 13}C labeled standards can be used to control the δ{sup 13}C value and produce manipulated T which cannot be detected by the current method. A method was explored to remove the {sup 13}C labeled atom at C-3 from the molecule of androsterone (Andro), the metabolite of T in urine, to produce the resultant (A-nor-5α-androstane-2,17-dione, ANAD). The difference in δ{sup 13}C values between Andro and ANAD (Δδ{sup 13}C{sub Andro–ANAD}, ‰) would change significantly in case manipulated T is abused. Twenty-one volunteers administered T manipulated with different {sup 13}C labeled standards. The collected urine samples were analyzed with the established method, and the maximum value of Δδ{sup 13}C{sub Andro–ANAD} post ingestion ranged from 3.0‰ to 8.8‰. Based on the population reference, the cut-off value of Δδ{sup 13}C{sub Andro–ANAD} for positive result was suggested as 1.2‰. The developed method could be used to detect T manipulated with 3-{sup 13}C labeled standards.

  17. Changes in microbial structure and functional communities at different soil depths during 13C labelled root litter degradation

    Sanaullah, Muhammad; Baumann, Karen; Chabbi, Abad; Dignac, Marie-France; Maron, Pierre-Alain; Kuzyakov, Yakov; Rumpel, Cornelia

    2014-05-01

    Soil organic matter turnover depends on substrate quality and microbial activity in soil but little is known about how addition of freshly added organic material modifies the diversity of soil microbial communities with in a soil profile. We took advantage of a decomposition experiment, which was carried out at different soil depths under field conditions and sampled litterbags with 13C-labelled wheat roots, incubated in subsoil horizons at 30, 60 and 90 cm depth for up to 36 months. The effect of root litter addition on microbial community structure, diversity and activity was studied by determining total microbial biomass, PLFA signatures, molecular tools (DNA genotyping and pyrosequencing of 16S and 18S rDNAs) and extracellular enzyme activities. Automated ribosomal intergenic spacer analysis (ARISA) was also carried out to determine the differences in microbial community structure. We found that with the addition of root litter, total microbial biomass as well as microbial community composition and structure changed at different soil depths and change was significantly higher at top 30cm soil layer. Moreover, in the topsoil, population of both gram-positive and gram-negative bacteria increased with root litter addition over time, while subsoil horizons were relatively dominated by fungal community. Extra-cellular enzyme activities confirmed relatively higher fungal community at subsoil horizons compared with surface soil layer with bacteria dominant microbial population. Bacterial-ARISA profiling illustrated that the addition of root litter enhanced the abundance of Actinobacteria and Proteobacteria, at all three soil depths. These bacteria correspond to copiotrophic attributes, which can preferentially consume of labile soil organic C pools. While disappearance of oligotrophic Acidobacteria confirmed the shifting of microbial communities due to the addition of readily available substrate. We concluded that root litter mixing altered microbial community

  18. Identification of aquatically available carbon from algae through solution-state NMR of whole (13)C-labelled cells.

    Akhter, Mohammad; Dutta Majumdar, Rudraksha; Fortier-McGill, Blythe; Soong, Ronald; Liaghati-Mobarhan, Yalda; Simpson, Myrna; Arhonditsis, George; Schmidt, Sebastian; Heumann, Hermann; Simpson, André J

    2016-06-01

    Green algae and cyanobacteria are primary producers with profound impact on food web functioning. Both represent key carbon sources and sinks in the aquatic environment, helping modulate the dissolved organic matter balance and representing a potential biofuel source. Underlying the impact of algae and cyanobacteria on an ecosystem level is their molecular composition. Herein, intact (13)C-labelled whole cell suspensions of Chlamydomonas reinhardtii, Chlorella vulgaris and Synechocystis were studied using a variety of 1D and 2D (1)H/(13)C solution-state nuclear magnetic resonance (NMR) spectroscopic experiments. Solution-state NMR spectroscopy of whole cell suspensions is particularly relevant as it identifies species that are mobile (dissolved or dynamic gels), 'aquatically available' and directly contribute to the aquatic carbon pool upon lysis, death or become a readily available food source on consumption. In this study, a wide range of metabolites and structural components were identified within the whole cell suspensions. In addition, significant differences in the lipid/triacylglyceride (TAG) content of green algae and cyanobacteria were confirmed. Mobile species in algae are quite different from those in abundance in 'classic' dissolved organic matter (DOM) indicating that if algae are major contributors to DOM, considerable selective preservation of minor components (e.g. sterols) or biotransformation would have to occur. Identifying the metabolites and dissolved components within algal cells by NMR permits future studies of carbon transfer between species and through the food chain, whilst providing a foundation to better understand the role of algae in the formation of DOM and the sequestration/transformation of carbon in aquatic environments. PMID:27074782

  19. Atmospheric CO2 level affects plants' carbon use efficiency: insights from a 13C labeling experiment on sunflower stands

    Gong, Xiaoying; Schäufele, Rudi; Schnyder, Hans

    2015-04-01

    The increase of atmospheric CO2 concentration has been shown to stimulate plant photosynthesis and (to a lesser extent) growth, thereby acting as a possible sink for the additional atmospheric CO2. However, this effect is dependent on the efficiency with which plants convert atmospheric carbon into biomass carbon, since a considerable proportion of assimilated carbon is returned to the atmosphere via plant respiration. As a core parameter for carbon cycling, carbon use efficiency of plants (CUE, the ratio of net primary production to gross primary production) quantifies the proportion of assimilated carbon that is incorporated into plant biomass. CUE has rarely been assessed based on measurements of complete carbon balance, due to methodological difficulties in measuring respiration rate of plants in light. Moreover, foliar respiration is known to be inhibited in light, thus foliar respiration rate is generally lower in light than in dark. However, this phenomenon, termed as inhibition of respiration in light (IRL), has rarely been assessed at the stand-scale and been incorporated into the calculation of CUE. Therefore, how CUE responses to atmospheric CO2 levels is still not clear. We studied CUE of sunflower stands grown at sub-ambient CO2 level (200 μmol mol-1) and elevated CO2 level (1000 μmol mol-1) using mesocosm-scale gas exchange facilities which enabled continuous measurements of 13CO2/12CO2 exchange. Appling steady-state 13C labeling, fluxes of respiration and photosynthesis in light were separated, and tracer kinetic in respiration was analyzed. This study provides the first data on CUE at a mesocosm-level including respiration in light in different CO2 environments. We found that CUE of sunflower was lower at an elevated CO2 level than at a sub-ambient CO2 level; and the ignorance of IRL lead to erroneous estimations of CUE. Variation in CUE at atmospheric CO2 levels was attributed to several mechanisms. In this study, CO2 enrichment i) affected the

  20. Retrobiosynthetic NMR studies with 13C-labeled glucose. Formation of gallic acid in plants and fungi

    The biosynthesis of gallic acid was studied in cultures of the fungus Phycomyces blakesleeanus and in leaves of the tree Rhus typhina. Fungal cultures were grown with [1-13C]glucose or with a mixture of unlabeled glucose and [U-13C6]glucose. Young leaves of R. typhina were kept in an incubation chamber and were supplied with a solution containing a mixture of unlabeled glucose and [U-13C6]glucose via the leaf stem. Isotope distributions in isolated gallic acid and aromatic amino acids were analyzed by one-dimensional 1H and 13C NMR spectroscopy. A quantitative analysis of the complex isotopomer composition of metabolites was obtained by deconvolution of the 13C13C coupling multiplets using numerical simulation methods. This approach required the accurate analysis of heavy isotope chemical shift effects in a variety of different isotopomers and the analysis of long range 13C13C coupling constants. The resulting isotopomer patterns were interpreted using a retrobiosynthetic approach based on a comparison between the isotopomer patterns of gallic acid and tyrosine. The data show that both in the fungus and in the plant all carbon atoms of gallic acid are biosynthetically equivalent to carbon atoms of shikimate. Notably, the carboxylic group of gallic acid is derived from the carboxylic group of an early intermediate of the shikimate pathway and not from the side chain of phenylalanine or tyrosine. It follows that the committed precursor of gallic acid is an intermediate of the shikimate pathway prior to prephenate or arogenate, most probably 5-dehydroshikimate. A formation of gallic acid via phenylalanine, the lignin precursor, caffeic acid, or 3,4, 5-trihydroxycinnamic acid can be ruled out as major pathways in the fungus and in young leaves of R. typhina. The incorporation of uniformly 13C-labeled glucose followed by quantitative NMR analysis of isotopomer patterns is suggested as a general method for biosynthetic studies. As shown by the plant experiment, this

  1. GLOBAL MOLECULAR ANALYSES OF METHANE METABOLISM IN METHANOTROPHIC ALPHAPROTEOBACTERIUM, METHYLOSINUS TRICHOSPORIUM OB3B.PART II. METABOLOMICS AND 13C-LABELING STUDY

    Marina G. Kalyuzhanaya

    2013-04-01

    Full Text Available In this work we use metabolomics and 13C-labeling data to refine central metabolic pathways for methane utilization in Methylosinus trichosporium OB3b, a model alphaproteobacterial methanotrophic bacterium. We demonstrate here that similar to non-methane utilizing methylotrophic alphaproteobacteria the core metabolism of the microbe is represented by several tightly connected metabolic cycles, such as the serine pathway, the ethylmalonyl-CoA (EMC pathway, and the citric acid (TCA cycle. Both in silico estimations and stable isotope labeling experiments combined with single cell (NanoSIMS and bulk biomass analyses indicate that a significantly larger portion of the cell carbon (over 60% is derived from CO2 in this methanotroph. Our 13C-labeling studies revealed an unusual topology of the assimilatory network in which phosph(enolpyruvate/pyruvate interconversions are key metabolic switches. A set of additional pathways for carbon fixation are identified and discussed.

  2. Selective 'unlabeling' of amino acids in fractionally 13C labeled proteins: An approach for stereospecific NMR assignments of CH3 groups in Val and Leu residues

    A novel methodology for stereospecific NMR assignments of methyl (CH3) groups of Val and Leu residues in fractionally 13C-labeled proteins is presented. The approach is based on selective 'unlabeling' of specific amino acids in proteins while fractionally 13C-labeling the rest. A 2D [13C-1H] HSQC spectrum recorded on such a sample is devoid of peaks belonging to the 'unlabeled' amino acid residues. Such spectral simplification aids in unambiguous stereospecific assignment of diastereotopic CH3 groups in Val and Leu residues in large proteins. This methodology has been demonstrated on a 15 kDa calcium binding protein from Entamoeba histolytica (Eh-CaBP)

  3. Global Molecular Analyses of Methane Metabolism in Methanotrophic Alphaproteobacterium, Methylosinus trichosporium OB3b. Part II. Metabolomics and 13C-Labeling Study

    Yang, Song; Matsen, Janet B.; Konopka, Michael; Green-Saxena, Abigail; Clubb, Justin; Sadilek, Martin; Orphan, Victoria J; Beck, David; Kalyuzhnaya, Marina G.

    2013-01-01

    In this work we use metabolomics and ^(13)C-labeling data to refine central metabolic pathways for methane utilization in Methylosinus trichosporium OB3b, a model alphaproteobacterial methanotrophic bacterium. We demonstrate here that similar to non-methane utilizing methylotrophic alphaproteobacteria the core metabolism of the microbe is represented by several tightly connected metabolic cycles, such as the serine pathway, the ethylmalonyl-CoA (EMC) pathway, and the citric acid (TCA) cycle. ...

  4. Lack of 13C-label incorporation suggests low turnover rates of thaumarchaeal intact polar tetraether lipids in sediments from the Iceland shelf

    Lengger, S. K.; Lipsewers, Y. A.; de Haas, H.; Sinninghe Damsté, J. S.; Schouten, S.

    2014-01-01

    Thaumarchaeota are amongst the most abundant microorganisms in aquatic environments, however, their metabolism in marine sediments is still debated. Labeling studies in marine sediments have previously been undertaken, but focused on complex organic carbon substrates which Thaumarchaeota have not yet been shown to take up. In this study, we investigated the activity of Thaumarchaeota in sediments by supplying different 13C-labeled substrates which have previously been shown to be incorporated into archaeal cells in water incubations and/or enrichment cultures. We determined the incorporation of 13C-label from bicarbonate, pyruvate, glucose and amino acids into thaumarchaeal intact polar lipid-glycerol dibiphytanyl glycerol tetraethers (IPL-GDGTs) during 4-6 day incubations of marine sediment cores from three sites on the Iceland shelf. Thaumarchaeal intact polar lipids, in particular crenarchaeol, were detected at all stations and concentrations remained constant or decreased slightly upon incubation. No 13C incorporation in any IPL-GDGT was observed at stations 2 (clay-rich sediment) and 3 (organic-rich sediment). In bacterial/eukaryotic IPL-derived fatty acids at station 3, contrastingly, a large uptake of 13C label (up to + 80‰ ) was found. 13C was also respired during the experiment as shown by a substantial increase in the 13C content of the dissolved inorganic carbon. In IPL-GDGTs recovered from the sandy sediments at station 1, however, some enrichment in δ13C (1-4‰ ) was detected after incubation with bicarbonate and pyruvate. The low incorporation rates suggest a low activity of Thaumarchaeota in marine sediments and/or a low turnover rate of thaumarchaeal IPL-GDGTs due to their low degradation rates. Cell numbers and activity of sedimentary Thaumarchaeota based on IPL-GDGT measurements may thus have previously been overestimated.

  5. Lack of 13C-label incorporation suggests low turnover rates of thaumarchaeal intact polar tetraether lipids in sediments from the Iceland Shelf

    S. K. Lengger

    2013-08-01

    Full Text Available Thaumarchaeota are amongst the most abundant microorganisms in aquatic environments, however, their metabolism in marine sediments is still debated. Labeling studies in marine sediments have previously been undertaken, but focused on complex organic carbon substrates which Thaumarchaeota have not yet been shown to take up. In this study, we investigated the activity of Thaumarchaeota in sediments by supplying different 13C-labeled substrates which have previously been shown to be incorporated into archaeal cells in water incubations and/or enrichment cultures. We determined the incorporation of 13C-label from bicarbonate, pyruvate, glucose and amino acids into thaumarchaeal intact polar lipid-glycerol dibiphytanyl glycerol tetraethers (IPL-GDGTs during 4–6 day incubations of marine sediment cores from three different sites on the Iceland Shelf. Thaumarchaeal intact polar lipids were detected at all stations and concentrations remained constant or decreased slightly upon incubation. No 13C incorporation in any IPL-GDGT was observed at stations 2 (clay-rich sediment and 3 (organic-rich sediment. In bacterial/eukaryotic IPL-derived fatty acids at station 3, contrastingly, a large uptake of 13C label (up to +80‰ was found. 13C was also respired during the experiment as shown by a substantial increase in the 13C content of the dissolved inorganic carbon. In IPL-GDGTs recovered from the sandy sediments at station 1, however, some enrichment in 13C (1–4‰ was detected after incubation with bicarbonate and pyruvate. The low incorporation rates suggest a low activity of Thaumarchaeota in marine sediments and/or a low turnover rate of thaumarchaeal IPL-GDGTs due to their low degradation rates. Cell numbers and activity of sedimentary Thaumarchaeota based on IPL-GDGT measurements may thus have previously been overestimated.

  6. Contribution of carbohydrate and amino acids to the formation of aromatic structure of synthetic melanoidin (model sedimentary humic substance). A study using 13C-labeled glucose

    As a part of study to elucidate the source of aromatic structure in sedimentary humic substances (SHS), we synthesized melanoidins (a model SHS) from 13C-labeled glucose and non-labeled amino acids and examined how glucose and amino acids are involved in the formation of their aromatic structures. The synthesized melanoidin was oxidized by alkaline perman ganate and benzenecarboxylic acids in their degradation products were analyzed by Chemical Ionization-GC/MS. The results indicate that aromatic structures are formed in melanoidin as a result of both selfcondensation of glucose and a reaction between glucose and amino acids. (author)

  7. Molecular Investigation of the Short-term Sequestration of Natural Abundance 13C -labelled Cow Dung in the Surface Horizons of a Temperate Grassland Soil

    Dungait, J.; Bol, R.; Evershed, R. P.

    2004-12-01

    An adequate understanding of the carbon (C) sequestration potential of grasslands requires that the quantity and residence times of C inputs be measured. Herbivore dung is largely comprised of plant cell wall material, a significant source of stable C in intensively grazed temperate grassland ecosystems that contributes to the soil carbon budget. Our work uses compound-specific isotope analysis to identify the pattern of input of dung-derived compounds from natural abundance 13C/-labelled cow dung into the surface horizons of a temperate grassland soil over one year. C4 dung (δ 13C \\-12.6 ‰ ) from maize fed cows was applied to a temperate grassland surface (δ 13C \\-29.95 ‰ ) at IGER-North Wyke (Devon, UK), and dung remains and soil cores beneath the treatments collected at ŧ = 7, 14, 28, 56, 112, 224 and 372 days. Bulk dung carbon present in the 0\\-1 cm and 1\\-5 cm surface horizons of a grassland soil over one year was estimated using Δ 13C between C4 dung and C3 dung, after Bol {\\et al.} (2000). The major biochemical components of dung were quantified using proximate forage fibre analyses, after Goering and Van Soest (1970) and identified using `wet' chemical and GC-MS methods. Plant cell wall polysaccharides and lignin were found to account for up to 67 {%} of dung dry matter. Hydrolysed polysaccharides were prepared as alditol acetates for analyses (after Docherty {\\et al.}, 2001), and a novel application of an off-line pyrolysis method applied to measure lignin-derived phenolic compounds (after Poole & van Bergen, 2002). This paper focuses on major events in the incorporation of dung carbon, estimated using natural abundance 13C&-slash;labelling technique. This revealed a major bulk input of dung carbon after a period of significant rainfall with a consequent decline in bulk soil δ 13C values until the end of the experiment (Dungait {\\et al.}, submitted). Findings will be presented revealing contribution of plant cell wall polysaccharides and

  8. Measuring and modeling C flux rates through the central metabolic pathways in microbial communities using position-specific 13C-labeled tracers

    Dijkstra, P.; van Groenigen, K.; Hagerty, S.; Salpas, E.; Fairbanks, D. E.; Hungate, B. A.; KOCH, G. W.; Schwartz, E.

    2012-12-01

    The production of energy and metabolic precursors occurs in well-known processes such as glycolysis and Krebs cycle. We use position-specific 13C-labeled metabolic tracers, combined with models of microbial metabolic organization, to analyze the response of microbial community energy production, biosynthesis, and C use efficiency (CUE) in soils, decomposing litter, and aquatic communities. The method consists of adding position-specific 13C -labeled metabolic tracers to parallel soil incubations, in this case 1-13C and 2,3-13C pyruvate and 1-13C and U-13C glucose. The measurement of CO2 released from the labeled tracers is used to calculate the C flux rates through the various metabolic pathways. A simplified metabolic model consisting of 23 reactions is solved using results of the metabolic tracer experiments and assumptions of microbial precursor demand. This new method enables direct estimation of fundamental aspects of microbial energy production, CUE, and soil organic matter formation in relatively undisturbed microbial communities. We will present results showing the range of metabolic patterns observed in these communities and discuss results from testing metabolic models.

  9. Evidence for in situ degradation of mono-and polyaromatic hydrocarbons in alluvial sediments based on microcosm experiments with 13C-labeled contaminants

    A microcosm study was conducted to investigate the degradation of mono- and polyaromatic hydrocarbons under in situ-like conditions using alluvial sediments from the site of a former cokery. Benzene, naphthalene, or acenaphthene were added to the sediments as 13C-labeled substrates. Based on the evolution of 13C-CO2 determined by gas chromatography isotope-ratio mass spectrometry (GC-IRMS) it was possible to prove mineralization of the compound of interest in the presence of other unknown organic substances of the sediment material. This new approach was suitable to give evidence for the intrinsic biodegradation of benzene, naphthalene, and acenaphthene under oxic and also under anoxic conditions, due to the high sensitivity and reproducibility of 13C/12C stable isotope analysis. This semi-quantitative method can be used to screen for biodegradation of any slowly degrading, strongly sorbing compound in long-term experiments. - A method based on 13C-labeled substrates was developed to determine the intrinsic biodegradation potential of aromatic pollutants under oxic and under anoxic conditions

  10. Timing and magnitude of C partitioning through a young loblolly pine (Pinus taeda L.) stand using 13C labeling and shade treatments.

    Warren, J M; Iversen, C M; Garten, C T; Norby, R J; Childs, J; Brice, D; Evans, R M; Gu, L; Thornton, P; Weston, D J

    2012-06-01

    The dynamics of rapid changes in carbon (C) partitioning within forest ecosystems are not well understood, which limits improvement of mechanistic models of C cycling. Our objective was to inform model processes by describing relationships between C partitioning and accessible environmental or physiological measurements, with a special emphasis on short-term C flux through a forest ecosystem. We exposed eight 7-year-old loblolly pine (Pinus taeda L.) trees to air enriched with (13)CO(2) and then implemented adjacent light shade (LS) and heavy shade (HS) treatments in order to manipulate C uptake and flux. The impacts of shading on photosynthesis, plant water potential, sap flow, basal area growth, root growth and soil CO(2) efflux rate (CER) were assessed for each tree over a 3-week period. The progression of the (13)C label was concurrently tracked from the atmosphere through foliage, phloem, roots and surface soil CO(2) efflux. The HS treatment significantly reduced C uptake, sap flow, stem growth and fine root standing crop, and resulted in greater residual soil water content to 1 m depth. Soil CER was strongly correlated with sap flow on the previous day, but not the current day, with no apparent treatment effect on the relationship. Although there were apparent reductions in new C flux belowground, the HS treatment did not noticeably reduce the magnitude of belowground autotrophic and heterotrophic respiration based on surface soil CER, which was overwhelmingly driven by soil temperature and moisture. The (13)C label was immediately detected in foliage on label day (half-life = 0.5 day), progressed through phloem by Day 2 (half-life = 4.7 days), roots by Days 2-4, and subsequently was evident as respiratory release from soil which peaked between Days 3 and 6. The δ(13)C of soil CO(2) efflux was strongly correlated with phloem δ(13)C on the previous day, or 2 days earlier. While the (13)C label was readily tracked through the ecosystem, the fate of root C

  11. 13C-Labeled Heparan Sulfate Analogue as a Tool To Study Protein/Heparan Sulfate Interactions by NMR Spectroscopy: Application to the CXCL12α Chemokine

    Heparan sulfate (HS), a polysaccharide of the glycosaminoglycan family characterized by a unique level of complexity, has emerged as a key regulator of many fundamental biological processes. Although it has become clear that this class of molecules exert their functions by interacting with proteins, the exact modes of interaction still remain largely unknown. Here we report the engineering of a 13C-labeled HS-like oligosaccharide with a defined oligo-saccharidic sequence that was used to investigate the structural determinants involved in protein/HS recognition by multidimensional NMR spectroscopy. Using the chemokine CXCL12α as a model system, we obtained experimental NMR data on both the oligosaccharide and the chemokine that was used to obtain a structural model of a protein/HS complex. This new approach provides a foundation for further investigations of protein/HS interactions and should find wide application. (authors)

  12. Specific 13C labeling of leucine, valine and isoleucine methyl groups for unambiguous detection of long-range restraints in protein solid-state NMR studies

    Fasshuber, Hannes Klaus; Demers, Jean-Philippe; Chevelkov, Veniamin; Giller, Karin; Becker, Stefan; Lange, Adam

    2015-03-01

    Here we present an isotopic labeling strategy to easily obtain unambiguous long-range distance restraints in protein solid-state NMR studies. The method is based on the inclusion of two biosynthetic precursors in the bacterial growth medium, α-ketoisovalerate and α-ketobutyrate, leading to the production of leucine, valine and isoleucine residues that are exclusively 13C labeled on methyl groups. The resulting spectral simplification facilitates the collection of distance restraints, the verification of carbon chemical shift assignments and the measurement of methyl group dynamics. This approach is demonstrated on the type-three secretion system needle of Shigella flexneri, where 49 methyl-methyl and methyl-nitrogen distance restraints including 10 unambiguous long-range distance restraints could be collected. By combining this labeling scheme with ultra-fast MAS and proton detection, the assignment of methyl proton chemical shifts was achieved.

  13. Dynamics of the carbohydrate chains attached to the Fc portion of immunoglobulin G as studied by NMR spectroscopy assisted by selective 13C labeling of the glycans

    A systematic method for 13C labeling of the glycan of immunoglobulin G for NMR study has been developed. A mouse immunoglobulin of subclass IgG2b has been used for the experiment. On the basis of chemical shift and linewidth data, it has been concluded that (1) the mobility of the carbohydrate chain in IgG2b is comparable to that of the backbone polypeptide chain with the exception of the galactose residue at the nonreducing end of the Manα1-3 branch, which is extremely mobile and (2) agalactosylation does not induce any significant change in the mobility. The results obtained indicate that even in the agalactosyl form the glycans are buried in the protein. Biological significance of the NMR results obtained is also briefly discussed

  14. Simultaneous determination of seven β2-agonists in human and bovine urine by isotope dilution liquid chromatography-tandem mass spectrometry using compound-specific minimally (13)C-labelled analogues.

    González-Antuña, Ana; Rodríguez-González, Pablo; Centineo, Giuseppe; García Alonso, J Ignacio

    2014-10-29

    Seven β2-agonist (clenproperol, clenbuterol, salbutamol, bronbuterol, ractopamine, clenpenterol and clencyclohexerol) were determined simultaneously in human and bovine urine by isotope dilution LC-ESI-MS/MS in a triple quadrupole instrument. The method is based on the application of multiple linear regression in combination with compound-specific minimally (13)C-labelled analogues. Additionally, the increase of the bandpass of the first quadrupole during the selected reaction monitoring (SRM) measurement procedure allowed the simultaneous quantification of the seven compounds at sub ngg(-1) levels in a single chromatogram without resorting to a methodological calibration graph. Recovery values at concentration levels between 5.0 and 0.05ngg(-1) ranged from 95 to 110% in fortified bovine urine and from 91 to 108% in human urine, with relative standard deviations lower than 5% except for salbutamol and ractopamine. The proposed methodology was validated by analyzing the certified reference material BCR-503 (lyophilized bovine urine) certified for clenbuterol and salbutamol. The limits of detection (LOD) for a sample volume of 10mL of both human and bovine urine was found to be lower than 0.012ngg(-1) for all compounds, except to salbutamol in bovine urine which was of 0.029ngg(-1). The use of compound-specific isotopically labelled analogues minimally labelled in (13)C minimized the occurrence of isotope effects and corrected for matrix effects during ESI ionization and can be efficiently applied for the quantification of ultra-trace concentrations of β2-agonists in human and bovine urine. PMID:25468499

  15. Comprehensive signal assignment of 13C-labeled lignocellulose using multidimensional solution NMR and 13C chemical shift comparison with solid-state NMR.

    Komatsu, Takanori; Kikuchi, Jun

    2013-09-17

    A multidimensional solution NMR method has been developed using various pulse programs including HCCH-COSY and (13)C-HSQC-NOESY for the structural characterization of commercially available (13)C labeled lignocellulose from potatoes (Solanum tuberosum L.), chicory (Cichorium intybus), and corn (Zea mays). This new method allowed for 119 of the signals in the (13)C-HSQC spectrum of lignocelluloses to be assigned and was successfully used to characterize the structures of lignocellulose samples from three plants in terms of their xylan and xyloglucan structures, which are the major hemicelluloses in angiosperm. Furthermore, this new method provided greater insight into fine structures of lignin by providing a high resolution to the aromatic signals of the β-aryl ether and resinol moieties, as well as the diastereomeric signals of the β-aryl ether. Finally, the (13)C chemical shifts assigned in this study were compared with those from solid-state NMR and indicated the presence of heterogeneous dynamics in the polysaccharides where rigid cellulose and mobile hemicelluloses moieties existed together. PMID:24010724

  16. Incorporation of {sup 13}C-labeled intermediates into developing lignin revealed by analytical pyrolysis and CuO oxidation in combination with IRM-GC-MS

    Eglinton, T.I.; Goni, M.A. [Woods Hole Oceanographic Institution, MA (United States); Boon, J.J. [FOM Institute, Amsterdam (Netherlands)] [and others

    1995-12-31

    Tissue samples from Ginkgo shoots (Ginkgo biloba L.) and Rice grass (Oryzasitiva sp.) incubated in the presence of {sup 13}C-labeled substrates such as coniferin (postulated to be biosynthetic intermediates in lignin biosynthesis) were studied using thermal and chemical dissociation methods in combination with molecular-level isotopic measurements. The aim of the study was (1) to investigate dissociation mechanisms, and (2) to examine and quantify the proportions of labeled material incorporated within each sample. Isotopic analysis of specific dissociation products revealed the presence of the label in its original positions, and only within lignin-derived (phenolic) products. Moreover, the distribution and isotopic composition of the dissociation products strongly suggest an origin from newly-formed lignin. These results clearly indicate that there is no {open_quotes}scrambling{close_quotes} of carbon atoms as a result of the dissociation process, thereby lending support to this analytical approach. In addition, the data provide confidence in the selective labeling approach for elucidation of the structure and biosynthesis of lignin.

  17. Titration and exchange studies of liver fatty acid-binding protein with 13C-labeled long-chain fatty acids.

    Wang, Hsin; He, Yan; Kroenke, Christopher D; Kodukula, Sarala; Storch, Judith; Palmer, Arthur G; Stark, Ruth E

    2002-04-30

    Uniformly (13)C-labeled long-chain fatty acids were used to probe ligand binding to rat liver fatty acid-binding protein (LFABP), an atypical member of the fatty acid-binding protein (FABP) family that binds more than one molecule of long-chain fatty acid, accommodates a variety of diverse ligands, and exhibits diffusion-mediated lipid transport to membranes. Two sets of (1)H-(13)C resonances were found in a titration series of NMR spectra for oleate-LFABP complexes, indicating that two molecules of the fatty acid are situated in the protein cavity. However, no distinct resonances were observed for the excess fatty acid in solution, suggesting that at least one ligand undergoes rapid exchange with oleate in the bulk solution. An exchange rate of 54 +/- 6 s(-1) between the two sets of resonances was measured directly using (13)C z,z-exchange spectroscopy. In light of these NMR measurements, possible molecular mechanisms for the ligand-exchange process are evaluated and implications for the anomalous fatty acid transport mechanism of LFABP are discussed. PMID:11969406

  18. Accurate measurements of 13C-13C distances in uniformly 13C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    Application of sets of 13C-13C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important 13C-13C distances in uniformly 13C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl (13C′) and aliphatic (13Caliphatic) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly 13C,15N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of 13C′-13Caliphatic distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform 13C,15N-labeling on the FGAIL fragment

  19. A study of lignin degradation in leaf and needle litter using 13C-labelled tetramethylammonium hydroxide (TMAH) thermochemolysis: comparison with CuO oxidation and van Soest methods.

    T. Klotzbücher; T.R. Filley; K. Kaiser; K. Kalbitz

    2011-01-01

    We studied the degradation of lignin in leaf and needle litter of ash, beech, maple, pine and spruce using 13C-labelled tetramethylammonium hydroxide (13C TMAH) thermochemolysis. Samples were allowed to decompose for 27 months in litter bags at a German spruce forest site, resulting in a range of ma

  20. Assigning large proteins in the solid state: a MAS NMR resonance assignment strategy using selectively and extensively {sup 13}C-labelled proteins

    Higman, Victoria A. [Leibniz-Institut fuer Molekulare Pharmakologie (Germany); Flinders, Jeremy [Genentech, Inc., Structural Biology Department (United States); Hiller, Matthias; Jehle, Stefan; Markovic, Stefan; Fiedler, Sebastian; Rossum, Barth-Jan van; Oschkinat, Hartmut [Leibniz-Institut fuer Molekulare Pharmakologie (Germany)], E-mail: oschkinat@fmp-berlin.de

    2009-08-15

    In recent years, solid-state magic-angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) has been growing into an important technique to study the structure of membrane proteins, amyloid fibrils and other protein preparations which do not form crystals or are insoluble. Currently, a key bottleneck is the assignment process due to the absence of the resolving power of proton chemical shifts. Particularly for large proteins (approximately >150 residues) it is difficult to obtain a full set of resonance assignments. In order to address this problem, we present an assignment method based upon samples prepared using [1,3-{sup 13}C]- and [2-{sup 13}C]-glycerol as the sole carbon source in the bacterial growth medium (so-called selectively and extensively labelled protein). Such samples give rise to higher quality spectra than uniformly [{sup 13}C]-labelled protein samples, and have previously been used to obtain long-range restraints for use in structure calculations. Our method exploits the characteristic cross-peak patterns observed for the different amino acid types in {sup 13}C-{sup 13}C correlation and 3D NCACX and NCOCX spectra. An in-depth analysis of the patterns and how they can be used to aid assignment is presented, using spectra of the chicken {alpha}-spectrin SH3 domain (62 residues), {alpha}B-crystallin (175 residues) and outer membrane protein G (OmpG, 281 residues) as examples. Using this procedure, over 90% of the C{alpha}, C{beta}, C' and N resonances in the core domain of {alpha}B-crystallin and around 73% in the flanking domains could be assigned (excluding 24 residues at the extreme termini of the protein)

  1. Assigning large proteins in the solid state: a MAS NMR resonance assignment strategy using selectively and extensively 13C-labelled proteins

    In recent years, solid-state magic-angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) has been growing into an important technique to study the structure of membrane proteins, amyloid fibrils and other protein preparations which do not form crystals or are insoluble. Currently, a key bottleneck is the assignment process due to the absence of the resolving power of proton chemical shifts. Particularly for large proteins (approximately >150 residues) it is difficult to obtain a full set of resonance assignments. In order to address this problem, we present an assignment method based upon samples prepared using [1,3-13C]- and [2-13C]-glycerol as the sole carbon source in the bacterial growth medium (so-called selectively and extensively labelled protein). Such samples give rise to higher quality spectra than uniformly [13C]-labelled protein samples, and have previously been used to obtain long-range restraints for use in structure calculations. Our method exploits the characteristic cross-peak patterns observed for the different amino acid types in 13C-13C correlation and 3D NCACX and NCOCX spectra. An in-depth analysis of the patterns and how they can be used to aid assignment is presented, using spectra of the chicken α-spectrin SH3 domain (62 residues), αB-crystallin (175 residues) and outer membrane protein G (OmpG, 281 residues) as examples. Using this procedure, over 90% of the Cα, Cβ, C' and N resonances in the core domain of αB-crystallin and around 73% in the flanking domains could be assigned (excluding 24 residues at the extreme termini of the protein)

  2. Production of Hydrolysable Tannin-Like Structures During the Microbial Demethylation of lignin: An Assessment Using13C-Labeled Tetramethylammonium Hydroxide Thermochemolysis.

    Filley, T.; Blanchette, R.; Nierop, K.; Gamblin, D.

    2003-12-01

    Phenolic compounds in soils are important mediators of microbial activity, metal mobility, soil redox, and soil organic matter building processes. Direct tannin input and the microbial decomposition of lignin in litter and soil are important contributors to this pool of phenols. The ability to accurately assess the relative differences in lignin decay (which are initiated by demethylation and side chain oxidation) among synapyl, coniferyl, and p-coumaryl components of detrital lignin requires the ability to determine microbial demethylation within the complex soil residues. Differentiating between hydrolysable tannins and contributions from advanced lignin decay can be problematic for many of the most common molecular techniques such as alkaline CuO oxidation, pyrolysis GC, and tetramethylammonium hydroxide thermochemolysis because of either the masking effects of derivatizing agents, oxidative damage to ortho-phenols or low volatility of lignin monomers. In this study we investigate lignin demethylation and polyhydroxyl-aromatic production in BC and C horizons of sandy forest soils dominated by oak, the A horizon from a red spruce forest, and controlled microbial inoculation studies of woody tissue using in-line 13C-labeled tetramethylammonium hydroxide thermochemolysis. Both white-rot and brown-rot decay resulted in syringyl demethylation, with the latter exhibiting more aggressive demethylation chemistry, while coniferyl monomer demethylation was essentially restricted to brown-rot decay. In a typical brown-rot sequence demethylation of syringyl components occurs more rapidly than coniferyl units within the same tissue and lower molecular weight fragments are likewise more demethylated than lignin monomers containing the full glycerol side chain. Demethylation of both methoxyl groups in the syringyl monomer is evident in soil horizons as well as laboratory inoculations. The latter may suggest demethylation after lignin depolymerization. Low molecular weight

  3. Selective 'unlabeling' of amino acids in fractionally 13C labeled proteins: An approach for stereospecific NMR assignments of CH3 groups in Val and Leu residues

    Atreya, H.S.; Chary, K.V.R. [Tata Institute of Fundamental Research, Department of Chemical Sciences (India)

    2001-03-15

    A novel methodology for stereospecific NMR assignments of methyl (CH{sub 3}) groups of Val and Leu residues in fractionally {sup 13}C-labeled proteins is presented. The approach is based on selective 'unlabeling' of specific amino acids in proteins while fractionally {sup 13}C-labeling the rest. A 2D [{sup 13}C-{sup 1}H] HSQC spectrum recorded on such a sample is devoid of peaks belonging to the 'unlabeled' amino acid residues. Such spectral simplification aids in unambiguous stereospecific assignment of diastereotopic CH{sub 3} groups in Val and Leu residues in large proteins. This methodology has been demonstrated on a 15 kDa calcium binding protein from Entamoeba histolytica (Eh-CaBP)

  4. Investigation of the degradation of 13C-labeled fungal biomass in soil - fate of carbon in a soil bioreactor system

    Schweigert, Michael; Fester, Thomas; Miltner, Anja; Kaestner, Matthias

    2015-04-01

    significant incorporation of L. bicolor-derived carbon into a wide variety of different bacterial taxa, indicating the relevance of fungal biomass residues for soil bacteria as a carbon source. In a later phase of the experiment, we will also trace the fate of soil organic carbon into the fungal biomass and the plant partner (Picea abies). These results will provide a comprehensive view of the role of ectomycorrhizal fungi and their residues on soil carbon cycling.

  5. Metabolic turnover analysis by a combination of in vivo 13C-labelling from 13CO2 and metabolic profiling with CE-MS/MS reveals rate-limiting steps of the C3 photosynthetic pathway in Nicotiana tabacum leaves

    Hasunuma, Tomohisa; Harada, Kazuo; Miyazawa, Shin-Ichi; Kondo, Akihiko; Fukusaki, Eiichiro; Miyake, Chikahiro

    2009-01-01

    Understanding of the control of metabolic pathways in plants requires direct measurement of the metabolic turnover rate. Sugar phosphate metabolism, including the Calvin cycle, is the primary pathway in C3 photosynthesis, the dynamic status of which has not been assessed quantitatively in the leaves of higher plants. Since the flux of photosynthetic carbon metabolism is affected by the CO2 fixation rate in leaves, a novel in vivo 13C-labelling system was developed with 13CO2 for the kinetic d...

  6. [Determination of trace organochlorine pesticides in soil using isotope dilution-high resolution gas chromatography].

    Huang, Wenjun; Gao, Lirong; Gong, Aijun; Li, Cheng; Wang, Pu; Fu, Shan; Xiao, Ke; Zhang, Bing; Liu, Wenbin

    2010-05-01

    A method for the determination of trace organochlorine pesticides (OCPs) in soil using isotope dilution and high resolution gas chromatography-high resolution mass spectrometry (ID-HRGC-HRMS) was developed. The sample was extracted by accelerated solvent extractor (ASE) and cleaned-up by a Florisil solid phase extraction (SPE) cartridge. The analytes were separated by HRGC on a DB-5MS column (30 mx 0.25 mm x 0.25 microm) and determined by HRMS. The identifications of OCPs were based on the retention time of 13C-labelled standard and the abundance ratio of the two exact mass-to-charge ratios. The quantitative analysis was performed using the ratios of the integrated areas of the 13C-labelled standards. This method has the recoveries ranging from 77.3% to 114.5% and the relative standard deviations (RSD) less than 10.81% (n=5). The limits of detection (LODs) of this method for all OCPs were lower than 0.04 pg/g. The results indicated that the method is rapid, selective and sensitive for precise determination requirements of organochlorine pesticides at trace level in soil. PMID:20812621

  7. Synthesis of 13C-labeled methanol

    A novel convenient method for the synthesis of 13C-methanol was described. 13C- methanol was prepared by means of catalytic hydrogenation, and then as-synthesized methanol solution was further purified in a microscale high-efficient rectification column. The chemical purity of 13C-methanol was more than 99.5%. The synthetic route was featured by mild conditions and high yields of more than 90% based on isotopic substrate consumed. The product was characterized by GC-MS and 1H NMR, and the 13C abundance of 13C- methanol was more than 97%. Compared with the raw materials, the reduction of relative isotopic abundance of product was less than 1%. (authors)

  8. Uniform {sup 15}N- and {sup 15}N/{sup 13}C-labeling of proteins in mammalian cells and solution structure of the amino terminal fragment of u-PA

    Hansen, A.P.; Petros, A.M.; Meadows, R.P.; Mazar, A.P.; Nettesheim, D.G.; Pederson, T.M.; Fesik, S.W. [Abbott Laboratories, Abbott Park, IL (United States)

    1994-12-01

    Urokinase-type plasminogen activator (u-PA) is a 54-kDa glycoprotein that catalyzes the conversion of plasminogen to plasmin, a broad-specificity protease responsible for the degradation of fibrin clots and extracellular matrix components. The u-PA protein consists of three individual modules: a growth factor domain (GFD), a kringle, and a serine protease domain. The amino terminal fragment (ATF) includes the GFD-responsible for u-PA binding to its receptor-and the kringle domains. This protein was expressed and uniformly {sup 15}N-and {sup 15}N/{sup 13}C-labeled in mammalian cells by methods that will be described. In addition, we present the three-dimensional structure of ATF that was derived from 1299 NOE-derived distance restraints along with the {phi} angle and hydrogen bonding restraints. Although the individual domains in the structures were highly converged, the two domains are structurally independent. The overall structures of the individual domains are very similar to the structures of homologous proteins. However, important structural differences between the growth factor domain of u-PA and other homologous proteins were observed in the region that has been implicated in binding the urokinase receptor. These results may explain, in part, why other growth factors show no appreciable affinity for the urokinase receptor.

  9. Spatial and temporal distribution of 13C labelled plant residues in soil aggregates and Lumbricus terrestris surface casts: A combination of Transmission Electron Microscopy and Nanoscale Secondary Ion Mass Spectrometry

    Vidal, Alix; Remusat, Laurent; Watteau, Françoise; Derenne, Sylvie; Quenea, Katell

    2016-04-01

    Earthworms play a central role in litter decomposition, soil structuration and carbon cycling. They ingest both organic and mineral compounds which are mixed, complexed with mucus and dejected in form of casts at the soil surface and along burrows. Bulk isotopic or biochemical technics have often been used to study the incorporation of litter in soil and casts, but they could not reflect the complex interaction between soil, plant and microorganisms at the microscale. However, the heterogeneous distribution of organic carbon in soil structures induces contrasted microbial activity areas. Nano-scale secondary ion mass spectrometry (NanoSIMS), which is a high spatial resolution method providing elemental and isotopic maps of organic and mineral materials, has recently been applied in soil science (Herrmann et al., 2007; Vogel et al., 2014). The combination of Nano-scale secondary ion mass spectrometry (NanoSIMS) and Transmission Electron Microscopy (TEM) has proven its potential to investigate labelled residues incorporation in earthworm casts (Vidal et al., 2016). In line of this work, we studied the spatial and temporal distribution of plant residues in soil aggregates and earthworm surface casts. This study aimed to (1) identify the decomposition states of labelled plant residues incorporated at different time steps, in casts and soil, (2) identify the microorganisms implied in this decomposition (3) relate the organic matter states of decomposition with their 13C signature. A one year mesocosm experiment was set up to follow the incorporation of 13C labelled Ryegrass (Lolium multiflorum) litter in a soil in the presence of anecic earthworms (Lumbricus terrestris). Soil and surface cast samples were collected after 8 and 54 weeks, embedded in epoxy resin and cut into ultra-thin sections. Soil was fractionated and all and analyzed with TEM and NanoSIMS, obtaining secondary ion images of 12C, 16O, 12C14N, 13C14N and 28Si. The δ13C maps were obtained using the 13C14

  10. An automated GCxGC-TOF-MS protocol for batch-wise extraction and alignment of mass isotopomer matrixes from differential 13C-labelling experiments: a case study for photoautotrophic-mixotrophic grown Chlamydomonas reinhardtii cells.

    Kempa, Stefan; Hummel, Jan; Schwemmer, Thorsten; Pietzke, Matthias; Strehmel, Nadine; Wienkoop, Stefanie; Kopka, Joachim; Weckwerth, Wolfram

    2009-02-01

    Two dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOF-MS) is a promising technique to overcome limits of complex metabolome analysis using one dimensional GC-TOF-MS. Especially at the stage of data export and data mining, however, convenient procedures to cope with the complexity of GCxGC-TOF-MS data are still in development. Here, we present a high sample throughput protocol exploiting first and second retention index for spectral library search and subsequent construction of a high dimensional data matrix useful for statistical analysis. The method was applied to the analysis of (13)C-labelling experiments in the unicellular green alga Chlamydomonas reinhardtii. We developed a rapid sampling and extraction procedure for Chlamydomonas reinhardtii laboratory strain (CC503), a cell wall deficient mutant. By testing all published quenching protocols we observed dramatic metabolite leakage rates for certain metabolites. To circumvent metabolite leakage, samples were directly quenched and analyzed without separation of the medium. The growth medium was adapted to this rapid sampling protocol to avoid interference with GCxGC-TOF-MS analysis. To analyse batches of samples a new software tool, MetMax, was implemented which extracts the isotopomer matrix from stable isotope labelling experiments together with the first and second retention index (RI1 and RI2). To exploit RI1 and RI2 for metabolite identification we used the Golm metabolome database (GMD [1] with RI1/RI2-reference spectra and new search algorithms. Using those techniques we analysed the dynamics of (13)CO(2) and (13)C-acetate uptake in Chlamydomonas reinhardtii cells in two different steady states namely photoautotroph and mixotroph growth conditions. PMID:19206143

  11. Density estimates for phase transitions with a trace

    Sire, Yannick

    2010-01-01

    We consider a functional obtained by adding a trace term to the Allen-Cahn phase segregation model and we prove some density estimates for the level sets of the interfaces. We treat in a unified way also the cases of possible degeneracy and singularity of the ellipticity of the model and the quasiminimal case.

  12. Synthesis of 13C labelled lactose for metabolic studies

    The most common cause of diarrhoea in Uruguay is lactose intolerance, and to determine the origin of diarrhoea in individual cases a deep and fast clinical method is highly desirable. The present report discusses the synthesis of c-13-labelled lactose and two separation methods for detecting sugars in samples of faeces

  13. High temporal resolution tracing of xylem CO2 transport in oak trees

    Bloemen, Jasper; Ingrisch, Johannes; Bahn, Michael

    2016-04-01

    Carbon (C) allocation defines the flows of C between plant organs and their storage pools and metabolic processes and is therefore considered as an important determinant of forest C budgets and their responses to climate change. In trees, assimilates derived from leaf photosynthesis are transported via the phloem to above- and belowground sink tissues, where partitioning between growth, storage, and respiration occurs. At the same time, root- and aboveground respired CO2 can be dissolved in water and transported in the xylem tissue, thereby representing a C flux of large magnitude whose role in C allocation yet is unresolved. In this study, we infused 13C labeled water into the stem base of five year old potted oak (Quercus rubra) trees as a surrogate for respired CO2 to investigate the role of respired CO2 transport in trees in C allocation. We used high-resolution laser-based measurements of the isotopic composition of stem and soil CO2 efflux combined with stem gas probes to monitor the transport of 13C label. The high enrichment of the gas probes in the stem at the bottom of the canopy showed that the label was transported upwards from the base of the tree toward the top. During its ascent, the 13C label was removed from the transpiration stream and lost to the atmosphere at stem level, as was observed using the stem CO2 efflux laser-based measurements. This study is the first to show results from tracing xylem CO2 transport in trees at high temporal resolution using a 13C labeling approach. Moreover, they extend results from previous studies on internal CO2 transport in species with high transpiration rates like poplar to species with lower transpiration rates like oak. Internal transport of CO2 indicates that the current concepts of the tree C allocation need to be revisited, as they show that current gas exchange approach to estimating above- and belowground autotrophic respiration is inadequate.

  14. Effects of source and receiver locations in predicting room transfer functions by a phased beam tracing method

    Jeong, Cheol-Ho; Ih, Jeong-Guon

    2012-01-01

    The accuracy of a phased beam tracing method in predicting transfer functions is investigated with a special focus on the positions of the source and receiver. Simulated transfer functions for various source-receiver pairs using the phased beam tracing method were compared with analytical Green’s...

  15. Analytical calculation of spectral phase of grism pairs by the geometrical ray tracing method

    Rahimi, L.; Askari, A. A.; Saghafifar, H.

    2016-07-01

    The most optimum operation of a grism pair is practically approachable when an analytical expression of its spectral phase is in hand. In this paper, we have employed the accurate geometrical ray tracing method to calculate the analytical phase shift of a grism pair, at transmission and reflection configurations. As shown by the results, for a great variety of complicated configurations, the spectral phase of a grism pair is in the same form of that of a prism pair. The only exception is when the light enters into and exits from different facets of a reflection grism. The analytical result has been used to calculate the second-order dispersions of several examples of grism pairs in various possible configurations. All results are in complete agreement with those from ray tracing method. The result of this work can be very helpful in the optimal design and application of grism pairs at various configurations.

  16. Phased Beam Tracing Method Using the Reflection Coefficient Calculated from the Absorption Coefficient

    Jeong, Cheol-Ho; Ih, Jeong-Guon; Rindel, Jens Holger

    The phased beam tracing method (PBTM) is a technique which can calculate the pressure impulse response instead of energy impulse response, by taking the phase information into account. Inclusion of the phase information can extend the application of beam tracing technique to the mid frequency range...... in spite of the fact that the usual assumptions of geometric acoustics still hold. In the calculation of pressure impulse response, it is essential to have the reflection characteristics of the surfaces in the enclosed space. There is a method to obtain the reflection coefficient of the surface using...... the measured surface impedance. However, it is not always possible to get the measured impedance data of the surface, so that a practical way of getting reflection characteristics is needed. Generally, in the architectural acoustics field, the absorption coefficients have been employed in the...

  17. Nanometer-sized materials for solid-phase extraction of trace elements.

    Hu, Bin; He, Man; Chen, Beibei

    2015-04-01

    This review presents a comprehensive update on the state-of-the-art of nanometer-sized materials in solid-phase extraction (SPE) of trace elements followed by atomic-spectrometry detection. Zero-dimensional nanomaterials (fullerene), one-dimensional nanomaterials (carbon nanotubes, inorganic nanotubes, and nanowires), two-dimensional nanomaterials (nanofibers), and three-dimensional nanomaterials (nanoparticles, mesoporous nanoparticles, magnetic nanoparticles, and dendrimers) for SPE are discussed, with their application for trace-element analysis and their speciation in different matrices. A variety of other novel SPE sorbents, including restricted-access sorbents, ion-imprinted polymers, and metal-organic frameworks, are also discussed, although their applications in trace-element analysis are relatively scarce so far. PMID:25577358

  18. Two-phase wall friction model for the trace computer code

    The wall drag model in the TRAC/RELAP5 Advanced Computational Engine computer code (TRACE) has certain known deficiencies. For example, in an annular flow regime, the code predicts an unphysical high liquid velocity compared to the experimental data. To address those deficiencies, a new wall frictional drag package has been developed and implemented in the TRACE code to model the wall drag for two-phase flow system code. The modeled flow regimes are (1) annular/mist, (2) bubbly/slug, and (3) bubbly/slug with wall nucleation. The new models use void fraction (instead of flow quality) as the correlating variable to minimize the calculation oscillation. In addition, the models allow for transitions between the three regimes. The annular/mist regime is subdivided into three separate regimes for pure annular flow, annular flow with entrainment, and film breakdown. For adiabatic two-phase bubbly/slug flows, the vapor phase primarily exists outside of the boundary layer, and the wall shear uses single-phase liquid velocity for friction calculation. The vapor phase wall friction drag is set to zero for bubbly/slug flows. For bubbly/slug flows with wall nucleation, the bubbles are presented within the hydrodynamic boundary layer, and the two-phase wall friction drag is significantly higher with a pronounced mass flux effect. An empirical correlation has been studied and applied to account for nucleate boiling. Verification and validation tests have been performed, and the test results showed a significant code improvement. (authors)

  19. Trace metals partitioning among different sedimentary mineral phases and the deposit-feeding polychaete Armandia brevis.

    Díaz-de-Alba, Margarita; Huerta-Diaz, Miguel Angel; Delgadillo-Hinojosa, Francisco; Hare, Landis; Galindo-Riaño, M Dolores; Siqueiros-Valencia, Arturo

    2016-02-01

    Trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) were determined in two operationally defined fractions (HCl and pyrite) in sediments from Ensenada and El Sauzal harbors (Mexico). The HCl fraction had significantly higher metal concentrations relative to the pyrite fraction in both harbors, underlining the weak tendency of most trace metals to associate with pyrite. Exceptionally, Cu was highly pyritized, with degrees of trace metal pyritization (DTMP) >80% in both harbors. Dissolved Fe flux measurements combined with solid phase Fe sulfide data indicated that 98 mt of Fe are precipitated as iron sulfides every year in Ensenada Harbor. These Fe sulfides (and associated trace metals) will remain preserved in the sediments, unless they are perturbed by dredging or sediment resuspension. Calculations indicate that dredging activities could export to the open ocean 0.20±0.13 to (0.30±0.56)×10(3) mt of Cd and Cu, respectively, creating a potential threat to marine benthic organisms. Degrees of pyritization (DOP) values in Ensenada and El Sauzal harbors were relatively low (making it a useful biomonitor of sedimentary metal exposure. PMID:26595396

  20. Reconstruction of Sound Source Pressures in an Enclosure Using the Phased Beam Tracing Method

    Jeong, Cheol-Ho; Ih, Jeong-Guon

    2009-01-01

    Source identification in an enclosure is not an easy task due to complicated wave interference and wall reflections, in particular, at mid-high frequencies. In this study, a phased beam tracing method was applied to the reconstruction of source pressures inside an enclosure at medium frequencies...... all the pressure histories at the field points, source-observer relations can be constructed in a matrix-vector form for each frequency. By multiplying the measured field data with the pseudo-inverse of the calculated transfer function, one obtains the distribution of source pressure. An omni....... First, surfaces of an extended source are divided into reasonably small segments. From each source segment, one beam is projected into the field and all emitted beams are traced. Radiated beams from the source reach array sensors after traveling various paths including the wall reflections. Collecting...

  1. Determination of trace amount of iron in the PWR secondary water by solid phase spectroscopy (SPS)

    Solid phase spectroscopy (SPS) that is a potent analysis method of trace iron, based on the direct measurements of the degree of light-absorption by a cation-exchange resin which has adsorbed a Fe(II)-TPTZ complex, was applied to feedwater and moisture separator drain water of Genkai Nuclear Power Station as the alternative procedure to the TPTZ spectrophotometric method and ICP-MS method. The analytical results of real samples obtained by SPS were in good agreement with those by the TPTZ method after 16 times concentration of water samples. It was confirmed that SPS is simple and can make the analysis time short. SPS is evaluated to be applicable to trace analysis of iron in the PWR secondary water. (author)

  2. AQUEOUS TWO-PHASE GAS FLOATATION SPECTROPHOTOMETRIC DETERMINATION OF TRACE TETRACYCLINE IN ENVIRONMENTAL WATER SAMPLE

    HOU Yanmin; YAN Yongsheng; LI Chunxiang; ZHAO Xiaojun; WANG Liang

    2008-01-01

    A green method for separating and enriching trace tetracycline (TC) in environment water by Aqueous Two-phase Gas Fioatation Spectrophotometry has been proposed, the principium was discussed.In this paper, the hydrophobic complex composed of Mg(Ⅱ) and TC was floated into organic phase under the optimal conditions: pH=10, the floatatlon equipment is home-made, n-propyl alcohol as the organic solvent, sodium chloride as the separating phase reagent.The data were obtained by spectrophotometry after floatatlon; The linear regression ,equation is A=2.33×105 C(mol/L)+0.2179, linear range is from 3.77×107mol/L to 6.32×105mol/L, respectively, with the correlation coefficient (r) better than 0.9997, relative recoveries is 99.7% to 100.3%, limit of detection was 4.29×10-8mol/L, The method can be applied to analyse the trace TC in water sample, the result is better.

  3. Assessment of interfacial drag and two phase pressure drop models of TRACE code

    The TRAC-RELAP Advanced Computational Engine (TRACE) is currently under development by the US Nuclear Regulatory Commission (USNRC) as a next-generation thermal-hydraulics safety analysis code for reactor systems. To assess the interfacial drag and two-phase pressure drop models of the code to be used for the reactor core, an assessment program was initiated by the US NRC. This paper summarizes the TRACE (V5.0P1) code assessment for the adiabatic air-water flow in an 8x8 rod bundle geometry experiment. For this purpose, PIPE Component of the TRACE code was used. A node sensitivity study was also performed to check the effect of node size on code results. Void fraction and pressure drop were the parameters used for the comparison. The range of void fraction covered for the assessment was from 0.22 to 0.88. Code predicted pressure drop and void fraction data compared well with the experimental data with mean absolute error of 13% and 16.5% respectively. (author)

  4. Cadmium Extraction from Solutions by Solid-Phase and its Trace Determination

    A new sensitive and selective spectrophotometric method for determination of trace amounts of cadmium using a polyvinyl chloride membrane containing bis-(2-ethylhexyl)phthalate as a solid phase extraction medium was investigated. Bis-(2-ethylhexyl)phthalate has used as a plasticizer. Cd(II) in an aqueous solution was trapped on the membrane in the form of colorful Cd (II)-I- - MG complexes (which MG is malachite green) and the cadmium complex was concentrated in the membrane. The absorbance of the green membrane was measured at 629 nm using a spectrophotometer, and then, the concentration of the cadmium was calculated using a calibration curve, which expressed the relationship between the Cd(II) concentration and the membrane absorbance after coloring for 25 min. The calibration curve was linear in the range of 10-760 μgL-1 cadmium in the test solution. The detection limit based on the 3Sbl criterion was 1.8199 μgL-1 and the relative standard deviations (RSD) were less than 4 % (n=5). The proposed method has been successfully applied to the determination of trace amounts of cadmium in the Tadjan River water sample (Sari-Iran), and the mean value of 28.7 μgL-1 was obtained

  5. Determination of trace elements in acid rain by reversed phase extraction chromatography and neutron activation

    A preconcentration neutron activation analysis (PNAA) method has been developed for the simultaneous determination of selected trace elements in acid rain and other water samples. The method consists of preconcentration of the elements by reversed phase extraction chromatography using oxine-loaded Amberlite XAD-2 resin. Nearly 100% recoveries were obtained for Co, Cu, Hg, V and Zn at pH 6.0 and for Cd at pH 7.0. Manganese gave incomplete recoveries at the pH range of 4.0-8.0 studies. Various factors that can influence preconcentration of the elements have been investigated in detail. The precision and accuracy of measurements have been evaluated by analyzing certified reference materials. The detection limits have been found to be of the order of ppb. The PNAA method has been applied to a number of acid rain and other water samples

  6. Determination of trace elements in acid rain by reversed-phase extraction chromatography and neutron activation

    A preconcentration neutron activation analysis (PNAA) method involving reversed-phase extraction chromatography on 8-hydroxyquinoline-loaded Amberlite XAD-2 resin has been developed for the simultaneous determination of selected trace elements in acid rain and natural water samples. Quantitative retention has been achieved for Co, Cu, Hg, V and Zn at pH 6.0 and for Cd at pH 7.0. Various factors that can influence the preconcentration procedure have been studied in detail. Concentrations of the elements have been determined by the direct irradiation of the resin without eluting them from the column. Both precision and accuracy of the PNAA method are very good. The detection limits vary between 0.01 and 3 ppb. (author) 48 refs.; 2 figs.; 4 tabs

  7. SOLID PHASE MICROEXTRACTION FOR TRACE ANALYSIS OF BENZENE IN ENVIRONMENTAL MONITORING

    S. J. Shahtaheri, H. R. Heidari, F. Golbabaei, M. Alimohammadi, A. Rahimi Froshani

    2006-07-01

    Full Text Available Conventional analytical method for organic pollutants in water requires extraction of the pollutants, using hazardous solvent. Solid phase microextraction is a solvent free equilibrium extraction method, in which, proper calibration can allow quantitative determinations of organic pollutants at a very good sensitivity without the use of any organic solvent. Because individual volatile organic carbons are generally exposed environmentally and present in urine only at trace levels, a sensitive and accurate determination technique is essential. So, this study describes the optimization of headspace solid phase microextraction (HS-SPME followed by GC-FID for benzene in spiked urine. Through this investigations, the parameters affecting the extraction and gas chromatographic determination of analytes, including extraction time, temperature, desorption temperature, desorption time, salt addition, sample pH, sample volume and sample agitation were studied. An optimized headspace extraction was carried out at 30°C for 6 min in the presence of 0.2 g/mL of NaCl in the sample solution. Desorption of the analytes was carried out for 60 sec. at 250°C. The optimized procedure was also validated with three different pools of spiked urine samples and showed a good reproducibility over six consecutive days as well as six within-day experiments. The accuracy, linearity, detection limits were also determined. The headspace solid phase microextraction, GC-FID technique provides a relatively simple, convenient, practical procedure, which was here successfully applied to determine benzene in spiked urine.

  8. Study of road dust magnetic phases as the main carrier of potentially harmful trace elements.

    Bourliva, Anna; Papadopoulou, Lambrini; Aidona, Elina

    2016-05-15

    Mineralogical and morphological characteristics and heavy metal content of different fractions (bulk, non-magnetic fraction-NMF and magnetic fraction-MF) of road dusts from the city of Thessaloniki (Northern Greece) were investigated. Main emphasis was given on the magnetic phases extracted from these dusts. High magnetic susceptibility values were presented, whereas the MFs content of road dust samples ranged in 2.2-14.7wt.%. Thermomagnetic analyses indicated that the dominating magnetic carrier in all road dust samples was magnetite, while the presence of hematite and iron sulphides in the investigated samples cannot be excluded. SEM/EDX analyses identified two groups of ferrimagnetic particles: spherules with various surface morphologies and textures and angular/aggregate particles with elevated heavy metal contents, especially Cr. The road dusts (bulk samples) were dominated by calcium, while the mean concentrations of trace elements decreased in the order Zn>Mn>Cu>Pb>Cr>Ni>V>Sn>As >Sb>Co>Mo>W>Cd. MFs exhibited significantly higher concentrations of trace elements compared to NMFs indicating that these potentially harmful elements (PHEs) are preferentially enriched in the MFs and highly associated with the ferrimagnetic particles. Hazard Index (HI) obtained for both adults and children through exposure to bulk dust samples were lower or close to the safe level (=1). On the contrary, the HIs for the magnetic phases indicated that both children and adults are experiencing potential health risk since HI for Cr was significantly higher than safe level. Cancer risk due to road dust exposure is low. PMID:26930312

  9. A Study on the Characteristics of Phased Beam Tracing Method for the Acoustic Simulation of an Enclosure at Mid Frequencies

    Jeong, Cheol-Ho; Rindel, Jens Holger

    2006-01-01

    the phased method is advantageous compared to the conventional ray/beam tracing method: accurate prediction of early part of impulse response, better agreement with measured data, lower and extendable frequency range. This means that the technique can be employed in calculating the sound quality......High frequency acoustic analysis of an enclosure has been dealt with by geometrical acoustic techniques and low frequency response can be estimated by modal methods; however, mid frequency range has been a grey zone. The phased beam tracing method (PBTM) is one of the mid-frequency techniques...

  10. Phase partitioning of trace metals in a contaminated estuary influenced by industrial effluent discharge.

    Wang, Wenhao; Wang, Wen-Xiong

    2016-07-01

    Severe trace metal pollution due to industrial effluents releases was found in Jiulong River Estuary, Southern China. In this study, water samples were collected during effluent release events to study the dynamic changes of environmental conditions and metal partitioning among dissolved, particulate and colloidal phases controlled by estuarine mixing. Intermittent effluent discharges during low tide caused decreasing pH and dissolved oxygen, and induced numerous suspended particulate materials and dissolved organic carbon to the estuary. Different behaviors of Cu, Zn, Ni, Cr and Pb in the dissolved fraction against the conservative index salinity indicated different sources, e.g., dissolved Ni from the intermittent effluent. Although total metal concentrations increased markedly following effluent discharges, Cu, Zn, Cr, Pb were predominated by the particulate fraction. Enhanced adsorption onto particulates in the mixing process resulted in elevated partitioning coefficient (Kd) values for Cu and Zn, and the particle concentration effect was not obvious under such anthropogenic impacts. Colloidal proportion of these metals (especially Cu and Zn) showed positive correlations with dissolved or colloidal organic carbon, suggesting the metal-organic complexation. However, the calculated colloidal partitioning coefficients were relatively constant, indicating the excess binding capacity. Overall, the intermittent effluent discharge altered the particulate/dissolved and colloidal/soluble phase partitioning process and may further influence the bioavailability and potential toxicity to aquatic organisms. PMID:27061473

  11. Specific, trace gas induced phase transition in copper(II)oxide for highly selective gas sensing

    Kneer, J.; Wöllenstein, J.; Palzer, S.

    2014-08-01

    Here, we present results on the investigation of the percolation phase transition in copper(II)oxide (CuO) and show how it may be used to determine trace gas concentrations. This approach provides a highly selective sensing mechanism for the detection of hydrogen sulfide even in oxygen depleted atmospheres. In real-world applications, this scenario is encountered in biogas plants and natural gas facilities, where reliable H2S sensing and filtering are important because of the destructive effects H2S has on machinery. As opposed to gas detection via standard metal-oxide reaction routes, the percolation dynamics are demonstrated to be independent of the surface morphology in accordance with the universality of phase transitions. The sensing behavior of ink-jet printed CuO layers was tested for a large set of parameters including layer temperature, hydrogen sulfide (H2S) and oxygen concentration, as well as the sensitivity towards other gas species. The electrical percolation of the sensing layer is heralded by a dramatic drop in the overall resistivity of the CuO layer for temperatures below 200 °C. The observed percolation phenomena in this temperature regime are unique to H2S even in comparison with related volatile thio-compounds making the sensing mechanism highly selective. At elevated temperatures above 300 °C, the phase transition does not occur. This enables two distinct operational modes which are tunable via the sensor temperature and also allows for resetting the sensing layer after an electrical breakthrough.

  12. Critical review of conservation equations for two-phase flow in the U.S. NRC TRACE code

    Research highlights: → Field equations as implemented in TRACE are incorrect. → Boundary conditions needed for cooling of nuclear fuel elements are wrong. → The two-fluid model in TRACE is not closed. → Three-dimensional flow modeling in TRACE has no basis. - Abstract: The field equations for two-phase flow in the computer code TRAC/RELAP Advanced Computational Engine or TRACE are examined to determine their validity, their capabilities and limitations in resolving nuclear reactor safety issues. TRACE was developed for the NRC to predict thermohydraulic phenomena in nuclear power plants during operational transients and postulated accidents. TRACE is based on the rigorously derived and well-established two-fluid field equations for 1-D and 3-D two-phase flow. It is shown that: (1)The two-fluid field equations for mass conservation as implemented in TRACE are wrong because local mass balances in TRACE are in conflict with mass conservation for the whole reactor system, as shown in Section . (2)Wrong equations of motion are used in TRACE in place of momentum balances, compromising at branch points the prediction of momentum transfer between, and the coupling of, loops in hydraulic networks by impedance (form loss and wall shear) and by inertia and thereby the simulation of reactor component interactions. (3)Most seriously, TRACE calculation of heat transfer from fuel elements is incorrect for single and two-phase flows, because Eq. of the TRACE Manual is wrong (see Section ). (4)Boundary conditions for momentum and energy balances in TRACE are restricted to flow regimes with single-phase wall contact because TRACE lacks constitutive relations for solid-fluid exchange of momentum and heat in prevailing flow regimes. Without a quantified assessment of consequences from (3) to (4), predictions of phasic fluid velocities, fuel temperatures and important safety parameters, e.g., peak clad temperature, are questionable. Moreover, TRACE cannot predict 3-D single- or

  13. Critical review of conservation equations for two-phase flow in the U.S. NRC TRACE code

    Wulff, Wolfgang, E-mail: wolfgangwulff@optonline.net [11 Hamilton Road, Setauket, NY 11733 (United States)

    2011-10-15

    Research highlights: > Field equations as implemented in TRACE are incorrect. > Boundary conditions needed for cooling of nuclear fuel elements are wrong. > The two-fluid model in TRACE is not closed. > Three-dimensional flow modeling in TRACE has no basis. - Abstract: The field equations for two-phase flow in the computer code TRAC/RELAP Advanced Computational Engine or TRACE are examined to determine their validity, their capabilities and limitations in resolving nuclear reactor safety issues. TRACE was developed for the NRC to predict thermohydraulic phenomena in nuclear power plants during operational transients and postulated accidents. TRACE is based on the rigorously derived and well-established two-fluid field equations for 1-D and 3-D two-phase flow. It is shown that: (1)The two-fluid field equations for mass conservation as implemented in TRACE are wrong because local mass balances in TRACE are in conflict with mass conservation for the whole reactor system, as shown in Section . (2)Wrong equations of motion are used in TRACE in place of momentum balances, compromising at branch points the prediction of momentum transfer between, and the coupling of, loops in hydraulic networks by impedance (form loss and wall shear) and by inertia and thereby the simulation of reactor component interactions. (3)Most seriously, TRACE calculation of heat transfer from fuel elements is incorrect for single and two-phase flows, because Eq. of the TRACE Manual is wrong (see Section ). (4)Boundary conditions for momentum and energy balances in TRACE are restricted to flow regimes with single-phase wall contact because TRACE lacks constitutive relations for solid-fluid exchange of momentum and heat in prevailing flow regimes. Without a quantified assessment of consequences from (3) to (4), predictions of phasic fluid velocities, fuel temperatures and important safety parameters, e.g., peak clad temperature, are questionable. Moreover, TRACE cannot predict 3-D single- or two-phase

  14. Solid-phase extraction of trace metal ions with magnetic nanoparticles modified with 2,6-diaminopyridine

    We have modified silica-coated Fe3O4 nanoparticles with 2,6-diaminopyridine and used these for selective magnetic solid-phase extraction of trace amounts of metal ions. The nanoparticles were characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. Quantitative extraction of trace amounts of Cu(II) and Zn(II) from mixed-ion solutions was accomplished at an optimal pH value of 6 within less than 10 min. The metal ions were eluted from the sorbent with hydrochloric acid. Common electrolytes and chemically related metal ions do not interfere. The relative standard deviations of the method are <4 %. It was successfully applied to the separation and preconcentration of trace metal ions from the certified reference materials GBW 08301 (river sediment) and GBW 08607 (water solution), in natural water, and in samples of vegetable with satisfying results. (author)

  15. Solid phase extraction of trace amount of Cu(II) using functionalized-graphene

    Moghimi, Ali

    2013-11-01

    A novel and selective method for the fast determination of trace amounts of Cu(II) ions in water samples has been developed. The first organic-solution-processable functionalized-graphene (SPF-Graphene) hybrid material with porphyrins, porphyrin-graphene nanohybrid, 5-(4-aminophenyl)-10, 15, 20-triphenyl porphyrin and its photophysical properties including optical (TPP) and grapheme oxide molecules covalently bonded together via an amide bond (TPP-NHCO-SPFGraphene) were used as absorbent for extraction of Cu(II) ions by solid phase extraction method. The complexes were eluted with HNO3 (2 M) 10% (vol/vol) methanol in acetone and determined the analyte by flame atomic absorption spectrometry. The procedure is based on the selective formation of Cu(II) at optimum pH by elution with organic eluents and determination by flame atomic absorption spectrometry. The method is based on complex formation on the surface of the ENVI-18 DISK™ disks modified porphyrin-graphene nanohybrid, 5-(4-aminophenyl)-10,15,20-triphenyl porphyrin (TPP) and grapheme oxide molecules covalently bonded together via an amide bond (TPP-NHCO-SPFGraphene) followed by stripping of the retained species by minimum amounts of appropriate organic solvents. The elution is efficient and quantitative. The effect of potential interfering ions, pH, TPP-NHCO-SPFGraphene, amount, stripping solvent, and sample flow rate were also investigated. Under the optimal experimental conditions, the break-through volume was found to about 1000 mL providing a preconcentration factor of 600. The maximum capacity of the disks was found to be 398 ± 3 μg for Cu2+. The limit of detection of the proposed method is 5 ng per 1000 mL. The method was applied to the extraction and recovery of copper in different water samples.

  16. A solid-phase extraction method using Transcarpathian clinoptilolite for preconcentration of trace amounts of terbium in water samples

    Vasylechko, Volodymyr O.; Gryshchouk, Galyna V.; Zakordonskiy, Victor P.; Vyviurska, Olga; Pashuk, Andriy V.

    2015-01-01

    Background In spite of the fact that terbium is one of the rarest elements in the Earth’s crust, it is frequently used for the production of high technological materials. At the result, an effective combination of sample preparation procedure and detection method for terbium ions in different matrices is highly required. The solid-phase extraction procedure with natural Transcarpathian clinoptilolite thermally activated at 350 °C was used to preconcentrate trace amounts of terbium ions in aqu...

  17. Trace methane oxidation and the methane dependency of sulfate reduction in anaerobic granular sludge

    Meulepas, Roel J.W.

    2010-05-01

    This study investigates the oxidation of labeled methane (CH4) and the CH4 dependence of sulfate reduction in three types of anaerobic granular sludge. In all samples, 13C-labeled CH4 was anaerobically oxidized to 13C-labeled CO2, while net endogenous CH4 production was observed. Labeled-CH4 oxidation rates followed CH4 production rates, and the presence of sulfate hampered both labeled-CH4 oxidation and methanogenesis. Labeled-CH4 oxidation was therefore linked to methanogenesis. This process is referred to as trace CH4 oxidation and has been demonstrated in methanogenic pure cultures. This study shows that the ratio between labeled-CH4 oxidation and methanogenesis is positively affected by the CH4 partial pressure and that this ratio is in methanogenic granular sludge more than 40 times higher than that in pure cultures of methanogens. The CH4 partial pressure also positively affected sulfate reduction and negatively affected methanogenesis: a repression of methanogenesis at elevated CH4 partial pressures confers an advantage to sulfate reducers that compete with methanogens for common substrates, formed from endogenous material. The oxidation of labeled CH 4 and the CH4 dependence of sulfate reduction are thus not necessarily evidence of anaerobic oxidation of CH4 coupled to sulfate reduction. © 2010 Federation of European Microbiological Societies.

  18. Adsorption and reaction of trace gas-phase organic compounds on atmospheric water film surfaces: a critical review.

    Donaldson, D J; Valsaraj, Kalliat T

    2010-02-01

    The air-water interface in atmospheric water films of aerosols and hydrometeors (fog, mist, ice, rain, and snow) presents an important surface for the adsorption and reaction of many organic trace gases and gaseous reactive oxidants (hydroxyl radical (OH(.)), ozone (O(3)), singlet oxygen (O(2)((1)Delta(g))), nitrate radicals (NO(3)(.)), and peroxy radicals (RO(2)(.)). Knowledge of the air-water interface partition constant of hydrophobic organic species is necessary for elucidating the significance of the interface in atmospheric fate and transport. Various methods of assessing both experimental and theoretical values of the thermodynamic partition constant and adsorption isotherm are described in this review. Further, the reactivity of trace gases with gas-phase oxidants (ozone and singlet oxygen) at the interface is summarized. Oxidation products are likely to be more water-soluble and precursors for secondary organic aerosols in hydrometeors. Estimation of characteristic times shows that heterogeneous photooxidation in water films can compete effectively with homogeneous gas-phase reactions for molecules in the atmosphere. This provides further support to the existing thesis that reactions of organic compounds at the air-water interface should be considered in gas-phase tropospheric chemistry. PMID:20058916

  19. Reference Asian man phase-2 entitled 'Ingestion and organ content of trace elements of importance in radiological protection'

    The second phase of Reference Asian Man project was started with the collaboration of IAEA to strengthen the radiation protection infra-structure of the country. In this regard dietary samples are being collected from various ecological areas of Pakistan. The sample collection is being made on market basket method. Four diet samples were collected, prepared and stored in the refrigerator for analysis with the help of Neutron Activation Analysis (NAA) . The stable radio nuclide of our interest are Sr, Cs, Th, U, I. The other minor, essential trace and toxic elements are Ca, K, Mg, Na, Cu, Fe, Mn, Sc, Zn, Cd, Hg, and Pb. (author)

  20. Space Station Freedom Environmental Control and Life Support System (ECLSS) phase 3 simplified integrated test trace contaminant control subsystem performance

    Perry, J. L.

    1990-01-01

    Space Station Freedom environmental control and life support system testing has been conducted at Marshall Space Flight Center since 1986. The phase 3 simplified integrated test (SIT) conducted from July 30, 1989, through August 11, 1989, tested an integrated air revitalization system. During this test, the trace contaminant control subsystem (TCCS) was directly integrated with the bleed stream from the carbon dioxide reduction subsystem. The TCCS performed as expected with minor anomalies. The test set the basis for further characterizing the TCCS performance as part of advance air revitalization system configurations.

  1. Prediction of Flow Regimes and Thermal Hydraulic Parameters in Two-Phase Natural Circulation by RELAP5 and TRACE Codes

    Viet-Anh Phung

    2015-01-01

    Full Text Available In earlier study we have demonstrated that RELAP5 can predict flow instability parameters (flow rate, oscillation period, temperature, and pressure in single channel tests in CIRCUS-IV facility. The main goals of this work are to (i validate RELAP5 and TRACE capabilities in prediction of two-phase flow instability and flow regimes and (ii assess the effect of improvement in flow regime identification on code predictions. Most of the results of RELAP5 and TRACE calculation are in reasonable agreement with experimental data from CIRCUS-IV. However, both codes misidentified instantaneous flow regimes which were observed in the test with high speed camera. One of the reasons for the incorrect identification of the flow regimes is the small tube flow regime transition model in RELAP5 and the combined bubbly-slug flow regime in TRACE. We found that calculation results are sensitive to flow regime boundaries of RELAP5 which were modified in order to match the experimental data on flow regimes. Although the flow regime became closer to the experimental one, other predicted thermal hydraulic parameters showed larger discrepancy with the experimental data than with the base case calculations where flow regimes were misidentified.

  2. Baseline Concentrations of Radionuclides and Trace Elements in Soils and Vegetation around the DARHT Facility: Construction Phase (1998)

    P. R. Fresquez; M. H. Ebinger; H. T. Haagenstad; L. Naranjo, Jr.

    1999-12-01

    The Mitigation Action Plan for the Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory mandates the establishment of baseline concentrations for potential environmental contaminants. To this end, concentrations of {sup 3}H, {sup 137}Cs, {sup 90}Sr, {sup 238}Pu, {sup 239,240}Pu, {sup 241}Am, and {sup tot}U and Ag, As, Ba, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, and Tl were determined in surface and subsurface soils, sediments, and vegetation (overstory and understory) around the DARHT facility during the construction phase in 1998 (this is the third of a four year baseline study). Also, volatile (VOC) and semivolatile (SVOC) organic compounds were measured in soils and sediments. Most radionuclides and trace metals in soil, sediment, and vegetation were similar to past years at DARHT and were within regional background concentrations. Exceptions were concentrations of {sup 90}Sr, Be, Ba, and total U in some samples--these elements exceeded upper limit regional background concentrations (e.g., >mean plus two std dev). No VOCs and very few SVOCs were detected in soils and sediments at DARHT. Mean ({+-} std dev) radionuclide and trace element concentrations measured in soil, sediment, and vegetation summarized over a three-year period (construction phase) are summarized.

  3. Evaluation of Two-Phase Flow Parameters of a Subcooled Boiling Flow in SUBO Test Using TRACE Code

    For licensing review of the Safety and Performance Analysis Code for Nuclear Power Plants (SPACE) developed by Korean nuclear industry, many separate/ integral/component effect tests (SET/IET/CETs) are being independently calculated with other safety analysis codes. Among several SETs, the subcooled boiling (SUBO) test under low pressure conditions was chosen to validate prediction capability of SPACE for subcooled boiling which is an important phenomenon for the safety analysis of nuclear reactor. In SUBO test carried out by Korea Atomic Energy Research Institute (KAERI), bubble behavior was investigated and local two-phase flow parameters were measured. In this study, the prediction capability of the TRACE code for subcooled boiling was identified with SUBO test results as an independent validation so as to compare to the results obtained by SPACE. The SUBO test under low pressure condition was analyzed with TRACE code. The major two-phase flow parameters including liquid velocity, void fraction and liquid temperature distribution are shown to be in good agreement with experimental results. However, there was the large difference in bubble velocity. Large local void fraction in several test cases which could be led by overestimated bubble velocity shall be resolved with further studies

  4. Determination of Trace Amount of Polycyclic Aromatic Hydrocarbons in Urban Sewage by Solid-phase Extraction Coupled with High Performance Liquid Chromatograph

    2011-01-01

    [Method] This study aimed to determine trace amount of polycyclic aromatic hydrocarbons(PAHs) in urban sewage by using solid-phase extraction(SPE) coupled with high performance liquid chromatograph(HPLC).[Method] From the aspects of solid-phase extraction column,elution solvent,elution volume,elution speed and so forth,the test conditions of SPE-HPLC method were optimized,and trace amount of PAHs in urban sewage was determined.[Result] The optimized solid-phase extraction conditions were SUPELCLEAN LC-18 so...

  5. Synthesis of /sup 13/C-labelled medroxyprogesterone acetate with three /sup 13/C isotopes (1)

    Rao, P.N.; Damodaran, K.M. (Southwest Foundation for Research and Education, San Antonio, TX (USA))

    1982-03-01

    17..cap alpha..-hydroxyprogesterone was condensed with phenyl acetate /sup 13/C/sub 2/ in the presence of sodium hydride. Treatment with acetic and hydrochloric acids and acetylation gave 17..cap alpha..-acetoxyprogesterone /sup 13/C/sub 2/. Treatment with tetrabromomethane /sup 13/C and hydrogenation yielded medroxyprogesterone acetate with three /sup 13/C isotopes.

  6. Synthesis of 13C-labelled medroxyprogesterone acetate with three 13C isotopes [1

    17α-hydroxyprogesterone was condensed with phenyl acetate 13C2 in the presence of sodium hydride. Treatment with acetic and hydrochloric acids and acetylation gave 17α-acetoxyprogesterone 13C2. Treatment with tetrabromomethane 13C and hydrogenation yielded medroxyprogesterone acetate with three 13C isotopes. (U.K.)

  7. Oxidation of 13C-labelled glucose during exercise of different intensity

    An experiment is reported in assessing the percentage utilization of glucose labelled with natural isotope 13C during intense exercise on a bicycle ergometer (I) (1 hr, 75% VO2max) and during light exercise (L) (1.5 hr 45% VO2max). Four healthy volunteers were administered 1.2 g.kg-1 labelled glucose dissolved in 400 ml water. The oxidation of the glucose was measured in expired 13CO2. In the course of exercise I, 15% were oxidized and during exercise L, 47% of the administered 13C glucose were oxidized. The difference in utilization of administered glucose during I and L exercises is significant (p<0.025). The blood sugar level rose significantly during exercise I, insulinemia increased during exercise I as well as L but in exercise I it was significantly lower as compared with exercise L (p<0.05). The investigation supplements findings on lower utilization of concentrated glucose solutions during intense physical exercise. (author). 3 figs., 2 tabs., 12 refs

  8. In situ Raman spectroelectrochemical study of 13C labeled fullerene peapods and double walled carbon nanotubes

    Kalbáč, Martin; Kavan, Ladislav; Zukalová, Markéta; Dunsch, L.

    2007-01-01

    Roč. 3, č. 10 (2007), s. 1746-1752. ISSN 1613-6810 R&D Projects: GA AV ČR KJB400400601; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : Raman spectroscopy * spectroelectrochemistry * carbon nanotube Subject RIV: CG - Electrochemistry Impact factor: 6.408, year: 2007

  9. Laboratory-scale production of 13C-labeled lycopene and phytoene by bioengineered Escherichia coli.

    Lu, Chi-Hua; Choi, Jin-Ho; Engelmann Moran, Nancy; Jin, Yong-Su; Erdman, John W

    2011-09-28

    Consumption of tomato products has been associated with decreased risks of chronic diseases such as cardiovascular disease and cancer, and therefore the biological functions of tomato carotenoids such as lycopene, phytoene, and phytofluene are being investigated. To study the absorption, distribution, metabolism, and excretion of these carotenoids, a bioengineered Escherichia coli model was evaluated for laboratory-scale production of stable isotope-labeled carotenoids. Carotenoid biosynthetic genes from Enterobacter agglomerans were introduced into the BL21Star(DE3) strain to yield lycopene. Over 96% of accumulated lycopene was in the all-trans form, and the molecules were highly enriched with 13C by 13C-glucose dosing. In addition, error-prone PCR was used to disrupt phytoene desaturase (crtI) function and create a phytoene-accumulating strain, which was also found to maintain the transcription of phytoene synthase (crtB). Phytoene molecules were also highly enriched with 13C when the 13C-glucose was the only carbon source. The development of this production model will provide carotenoid researchers a source of labeled tracer materials to further investigate the metabolism and biological functions of these carotenoids. PMID:21888370

  10. One-carbon 13C-labeled synthetic intermediates. Comparison and evaluation of preparative methods

    Frequently the biggest stumbling block to the synthesis of a structurally complex labeled compound is obtaining the required low molecular weight, structurally simple, isotopic intermediates. Selection of a particular scheme from various alternatives depends on the available capabilities and quantity of product desired, as well as on anticipated future requirements and need for related compounds. Many of the newer reagents for organic synthesis can be applied effectively to isotopic preparations with improvements of yields and simplification of procedures compared to established classical methods. New routes developed for higher molecular weight compounds are sometimes not directly adaptable to the one-carbon analogs, either because of isolation difficulties occasioned by physical properties or by chemical reactivities peculiar to their being first members of homologous series. Various routes for preparation of carbon-13 labeled methanol, formaldehyde, and cyanide are compared

  11. 13Cα CEST experiment on uniformly 13C-labeled proteins

    A new HSQC-based 13Cα CEST pulse scheme is proposed, which is suitable for uniformly 13C- or 13C, 15N-labeled samples in either water or heavy water. Except for Thr and Ser residues, the sensitivity of this scheme for uniformly labeled samples is similar to that of the previous scheme for selectively 13Cα-labeled samples with 100 % isotope enrichment. The experiment is demonstrated on an acyl carrier protein domain. Our 13Cα CEST data reveal that the minor state of the acyl carrier protein has high helical propensity. The new scheme will facilitate structural characterization of invisible minor states

  12. Synthesis of 14C-labeled levamisole and 13C-labeled tetramisole

    The syntheses of 14C-ring labeled levamisole ([-]-2,3,5,6-tetrahydro-6-phenyl [14C]-UL]imidazo[2,1-b]thiazole) from acetophenone-ring-UL-14C in 5 steps plus resolution with a 7.5% overall yield, and 13C6-ring labeled tetramisole ([±]-2,3,5,6-tetrahydro-6-phenyl [13C6]imidazo[2,1-b]thiazole) from benzene-13C6 in 6 steps with a 9.0% overall yield are described. (author)

  13. Chromatographic measurements of the trace concentrations of the chloride compounds by gas phase coulometry

    The paper concerns the measurement of the trace concentration of the chloride compounds using the coefficient of the efficiency of the electron capture reaction which is determined by the method involving electron capture detectors (ECD) coopled in series. The theoretical model describing the performance of the two ECDs working in this mode was described. With help of this model and the experimental data the conditions necessary in order to achive the true coulometry were determined. The original method of the ECD calibration on the basis of the experimental data achieved in two different temperatures of the ECD was described. The analysis of the influence of the properties of the analysed compounds as well as the ECD parameters on the value of the electron capture efficiency was discussed. The performed analysis indicates that the space charge created inside the ECD should be taken into account in any ECD theoretical model. 15 figs., 42 refs. (author)

  14. Effect of the FCC to HCP Phase Transition on Trace Element Partitioning Between Metal and Sulfide Melt

    Campbell, A. J.; Thomas, R. B.; Fei, Y.

    2006-12-01

    Most of what we understand about the chemical behavior of iron alloys, even at high pressure, pertains to the fcc phase. However, it is widely thought that the relevant structure in the Earth's core is hcp, not fcc. In this study we aim to understand the effect of the fcc-hcp transition on siderophile element partitioning between metal and coexisting sulfide melt. This is important, for example, in evaluating models in which Re-Os-Pt isotope fractionations are attributed to partitioning between the Earth's inner and outer core. Experiments were doped with trace elements Ni, Re, Os, Ir, and Pt, which partitioned between Fe-Ru alloys and sulfide melt. Most experiments were performed at 1 bar in sealed silica tubes in a tube furnace, and some experiments were performed at 6 GPa in a multi-anvil press. The fcc-hcp transition was investigated by varying the Ru content of the experiments; the metal is fcc at Ru-poor compositions but hcp at higher Ru contents. The sulfur content of the melt varied with temperature and with bulk composition. The run products were characterized by electron microprobe, and abundances of the trace elements in both metal and melt were determined by laser ablation ICP-MS. The effect on partitioning of the phase transition can be distinguished from compositional effects because a range of Ru contents was studied. Our Ru-free dataare in good agreement with previously published data in the Fe-S system at 1 bar. However, our highest-Ru compositions show significant differences in their D values, attributable to the phase transition in the metal.

  15. Phase Random Walk Trace in High-order Coherence of Two First-order Incoherent Sources

    Hong, Peilong

    2014-01-01

    High-order coherence effects between two first-order incoherent sources with fully independent phases have been well studied in the literature, which shows interference fringes with respect to the position separations among different space points. Here we show that this is not the whole story, and find that the high-order coherence effects depend on the mode of the phase random walk of the first-order incoherent sources, which can be controlled artificially and represented geometrically by vectorial polygons. Interestingly, by scanning the detectors along the same direction with the position separations between them kept constant, a set of high-order coherence fringes, which fingerprint the phase random walk of the first-order incoherent sources, can be observed. Our results show that it is possible to control the high-order coherence of two first-order incoherent sources, which could have important practical applications such as superhigh resolution optical lithography.

  16. Shards of Broken Symmetry: Topological Defects as Traces of the Phase Transition Dynamics

    Zurek, W.H.; Bettencourt, L. M. A.; Dziarmaga, J.; Antunes, N. D.

    2010-01-01

    We discuss the origin of topological defects in phase transitions and analyze their role as a "diagnostic tool" in the study of the non-equilibrium dynamics of symmetry breaking. Homogeneous second order phase transitions are the focus of our attention, but the same paradigm is applied to the cross-over and inhomogeneous transitions. The discrepancy between the experimental results in 3He and 4He is discussed in the light of recent numerical studies. The possible role of the Ginzburg regime i...

  17. Determination of trace copper in food samples by flame atomic absorption spectrometry after solid phase extraction on modified soybean hull

    Xiang Guoqiang, E-mail: xianggq@126.com [School of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou 450001 (China); Zhang Yingming; Jiang Xiuming; He Lijun; Fan Lu; Zhao Wenjie [School of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou 450001 (China)

    2010-07-15

    Soybean hull was chemically modified with citric acid and used as a solid phase extraction adsorbent for the determination of trace amounts of Cu{sup 2+} in food samples by flame absorption spectrometry (FAAS). The effect of pH, sample flow rate and volume, elution flow rate and volume and co-existing ions on the recovery of the analyte were investigated. The results showed that Cu{sup 2+} could be adsorbed on the modified soybean hull at pH 8.0 and eluted by 2.0 mL of 1.0 mol L{sup -1} HCl. Under the optimized conditions, the adsorption capacity of modified soybean hull was found to be 18.0 mg g{sup -1} for Cu{sup 2+}. The detection limit of the proposed method was 0.8 ng mL{sup -1} for Cu{sup 2+} with an enrichment factor of 18. The analytical result for the certified reference tea sample (GBW07605) was in a good agreement with the certified value. The proposed method has also been successfully applied to the determination of trace Cu{sup 2+} in dried sweet potato, lake water and milk powder, the recovery of Cu{sup 2+} for spiked samples was between 91% and 109.6%.

  18. Determination of trace copper in food samples by flame atomic absorption spectrometry after solid phase extraction on modified soybean hull

    Soybean hull was chemically modified with citric acid and used as a solid phase extraction adsorbent for the determination of trace amounts of Cu2+ in food samples by flame absorption spectrometry (FAAS). The effect of pH, sample flow rate and volume, elution flow rate and volume and co-existing ions on the recovery of the analyte were investigated. The results showed that Cu2+ could be adsorbed on the modified soybean hull at pH 8.0 and eluted by 2.0 mL of 1.0 mol L-1 HCl. Under the optimized conditions, the adsorption capacity of modified soybean hull was found to be 18.0 mg g-1 for Cu2+. The detection limit of the proposed method was 0.8 ng mL-1 for Cu2+ with an enrichment factor of 18. The analytical result for the certified reference tea sample (GBW07605) was in a good agreement with the certified value. The proposed method has also been successfully applied to the determination of trace Cu2+ in dried sweet potato, lake water and milk powder, the recovery of Cu2+ for spiked samples was between 91% and 109.6%.

  19. Vapor phase treatment–total reflection X-ray fluorescence for trace elemental analysis of silicon wafer surface

    Vapor phase treatment (VPT) was under investigation by the International Organization for Standardization/Technical Committee 201/Working Group 2 (ISO/TC201/WG2) to improve the detection limit of total reflection X-ray fluorescence spectroscopy (TXRF) for trace metal analysis of silicon wafers. Round robin test results have confirmed that TXRF intensity increased by VPT for intentional contamination with 5 × 109 and 5 × 1010 atoms/cm2 Fe and Ni. The magnification of intensity enhancement varied greatly (1.2–4.7 in VPT factor) among the participating laboratories, though reproducible results could be obtained for average of mapping measurement. SEM observation results showed that various features, sizes, and surface densities of particles formed on the wafer after VPT. The particle morphology seems to have some impact on the VPT efficiency. High resolution SEM observation revealed that a certain number of dots with SiO2, silicate and/or carbon gathered to form a particle and heavy metals, Ni and Fe in this study were segregated on it. The amount and shape of the residue should be important to control VPT factor. - Highlights: • This paper presents a summary of study results of VPT–TXRF using ISO/TC201/WG2. • Our goal is to analyze the trace metallic contamination on silicon wafer with concentrations below 1 × 1010 atoms/cm2. • The efficiency and mechanism of VPT are discussed under several round robin tests and systematic studies

  20. Distribution of some trace elements in black sea and their flux between dissolved and particulate phases

    Brewer, P.G.; Spencer, D.W.

    1974-01-01

    The trace-element geochemistry of the Black Sea is dominated by the strong pycnocline separating the oxygenated and reducing environments. Using values of the vertical advective velocity and vertical eddy-diffusion coefficient derived from a model, the flux of dissolved sulfide, manganese, iron, copper, and zinc through this interface was estimated. The calculated sulfide flux of 145 mM/m/sup 2//year is smaller than estimates of sulfide production in the sediments by a factor of four, but is consistent with estimates of chemosynthesis, suggesting that a sulfide-removal mechanism not explained by the model must operate. From the manganese data, deductions were made that about 78 percent of the detrital load of rivers entering the Black Sea is deposited near the mouth of the river and only 22 percent is spread over the surface of the Black Sea. If the mean sinking rate is 1,000 m/year, the data on the distribution and elemental composition of particulate matter in the Black Sea are in agreement with estimates of river input. (auth)

  1. Redistribution of trace gases by convective clouds - mixed-phase processes

    Y. Yin

    2002-01-01

    Full Text Available The efficiency of gas transport to the free and upper troposphere in convective clouds is investigated in an axisymmetric dynamic cloud model with detailed microphysics. In particular, we examine the sensitivity of gas transport to the treatment of gas uptake by different ice hydrometeors. Two parameters are used to describe this uptake. The gas retention coefficient defines the fraction of dissolved gas that is retained in an ice particle upon freezing, which includes also the riming process. We also define a gas burial efficiency defining the amount of gas entrapped in ice crystals growing by vapour diffusion. Model calculations are performed for continental and maritime clouds using a complete range of gas solubilities, retention coefficients and burial efficiencies. The results show that the magnitude of the gas retention coefficient is much more important for gas transport in maritime clouds than in continental clouds. The cause of this difference lies in the different microphysical processes dominating the formation and evolution of hydrometeors in the two cloud types. For highly soluble gases, the amount of gas transported to the free troposphere in maritime clouds falls approximately linearly by a factor of 12 as the retention coefficient is varied between 0 and 1. Gas transport is relatively insensitive to the magnitude of the gas burial efficiency. However, the burial efficiency strongly controls the concentration of trace gases inside anvil ice crystals, which subsequently form cirrus clouds.

  2. Redistribution of trace gases by convective clouds – mixed-phase processes

    Y. Yin

    2002-06-01

    Full Text Available The efficiency of gas transport to the free and upper troposphere in convective clouds is investigated in an axisymmetric dynamic cloud model with detailed microphysics. In particular, we examine the sensitivity of gas transport to the treatment of gas uptake by different ice hydrometeors. Two parameters are used to describe this uptake. The gas retention coefficient defines the fraction of dissolved gas that is retained in an ice particle upon freezing, which includes also the riming process. We also define a gas burial efficiency defining the amount of gas entrapped in ice crystals growing by vapour diffusion. Model calculations are performed for continental and maritime clouds using a complete range of gas solubilities, retention coefficients and burial efficiencies. The results show that the magnitude of the gas retention coefficient is much more important for gas transport in maritime clouds than in continental clouds. The cause of this difference lies in the different microphysical processes dominating the formation and evolution of hydrometeors in the two cloud types. For highly soluble gases, the amount of gas transported to the free troposphere in maritime clouds falls approximately linearly by a factor of 12 as the retention coefficient is varied between 0 and 1. Gas transport is relatively insensitive to the magnitude of the gas burial efficiency. However, the burial efficiency strongly controls the concentration of trace gases inside anvil ice crystals, which subsequently form cirrus clouds.

  3. Preconcentration and Speciation of Trace Mercury Compounds in Water Sample Using Dithizonates Extraction and Reverse Phased Liquid Chromatography

    Suh, J.K.; Cho, K.H. [Korea Research Institute of Standards and Science, Taejon (Korea); Lee, S.H. [Kyungpook National University, Taegu (Korea)

    2000-02-01

    A rapid preconcentration method was developed for the speciation of the trace mercury compounds in water sample. The mercury compounds were extracted and preconcentrated simply as their dithizone complexes by passing through the dithizone impregnated ultra-high molecular weight polyethylene (CHMWPE) membrane solvent inlet filter following sonification in methanol solvent. The concentrated dithizonates were separated by liquid chromatography on a C{sub 18} column. Complete resolution was obtained between methyl-, ethyl-, phenyl-, and inorganic mercury with a mobile phase of 0.05 M acetate buffer (pH=4)/THF/methanol(3:5:2). The separated mercury chelates were detected by spectrophotometrically at 475 nm. The proposed method was successfully applied to the speciation of mercury compounds in waste water with detection limit at the subnanogram/mL level. (author). 15 refs., 2 tabs., 8 figs.

  4. Tracing symmetries and their breakdown through phases of heterotic (2,2) compactifications

    Blaszczyk, Michael; Oehlmann, Paul-Konstantin

    2016-04-01

    We are considering the class of heterotic N=(2,2) Landau-Ginzburg orbifolds with 9 fields corresponding to A 1 9 Gepner models. We classify all of its Abelian discrete quotients and obtain 152 inequivalent models closed under mirror symmetry with N=1 , 2 and 4 supersymmetry in 4D. We compute the full massless matter spectrum at the Fermat locus and find a universal relation satisfied by all models. In addition we give prescriptions of how to compute all quantum numbers of the 4D states including their discrete R-symmetries. Using mirror symmetry of rigid geometries we describe orbifold and smooth Calabi-Yau phases as deformations away from the Landau-Ginzburg Fermat locus in two explicit examples. We match the non-Fermat deformations to the 4D Higgs mechanism and study the conservation of R-symmetries. The first example is a Z_3 orbifold on an E6 lattice where the R-symmetry is preserved. Due to a permutation symmetry of blow-up and torus Kähler parameters the R-symmetry stays conserved also in the smooth Calabi-Yau phase. In the second example the R-symmetry gets broken once we deform to the geometric Z_3× Z_{3,free} orbifold regime.

  5. Shards of Broken Symmetry: Topological Defects as Traces of the Phase Transition Dynamics

    We discuss the origin of topological defects in phase transitions and analyze their role as a ''diagnostic tool'' in the study of the non-equilibrium dynamics of symmetry breaking. Homogeneous second order phase transitions are the focus of our attention, but the same paradigm is applied to the cross-over and inhomogeneous transitions. The discrepancy between the experimental results in 3He and 4He is discussed in the light of recent numerical studies. The possible role of the Ginzburg regime in determining the vortex line density for the case of a quench in 4He is raised and tentatively dismissed. The difference in the anticipated origin of the dominant signal in the two (3He and 4He) cases is pointed out and the resulting consequences for the subsequent decay of vorticity are noted. The possibility of a significant discrepancy between the effective field theory and (quantum) kinetic theory descriptions of the order parameter is briefly touched upon, using atomic Bose--Einstein condensates as an example. (author)

  6. {mu}X-ray fluorescence analysis of traces and calcium phosphate phases on tooth-tartar interfaces using synchrotron radiation

    Abraham, J.A. [Facultad de Matematica Astronomia y Fisica (UNC), 5000 Cordoba (Argentina); Grenon, M.S. [Facultad de Odontologia (UNC), 5000 Cordoba (Argentina); Sanchez, H.J. [Facultad de Matematica Astronomia y Fisica (UNC), 5000 Cordoba (Argentina)], E-mail: jsan@famaf.unc.edu.ar; Valentinuzzi, M.C. [Facultad de Matematica Astronomia y Fisica (UNC), 5000 Cordoba (Argentina); Perez, C.A. [Laboratorio Nacional de Luz Sincrotron, CP 6192 CEP, 13083-970 Campinas (Brazil)

    2007-07-15

    Hard dental tissues like dentine and cementum with calcified deposits (dental calculi) were studied in several human dental pieces of adult individuals from the same geographic region. A couple of cross cuts were performed at dental root level resulting in a planar slice with calculus and dental tissue exposed for analysis. The elemental content along a linear path crossing the dentine-cementum-tartar interfaces and also all over a surface was measured by X-ray fluorescence microanalysis using synchrotron radiation ({mu}SRXRF). The concentration of elemental traces like K, V, Cu, Zn, As, Br and Sr showed different features on the analyzed regions. The possible connections with the dynamic of mineralization and biological implications are discussed. The concentrations of major elements Ca and P were also determined and the measured Ca/P molar ratio was used to estimate the average composition of calcium phosphate phases in the measured points. A deeper knowledge of the variations of the elemental compositions and the changes of the different phases will help to a better understanding of the scarcely known mechanism of calculus growing.

  7. Vapor phase treatment–total reflection X-ray fluorescence for trace elemental analysis of silicon wafer surface

    Takahara, Hikari, E-mail: hikari@rigaku.co.jp [Rigaku Corp., 14-8 Akaoji-cho, Takatsuki, Osaka 569-1146 (Japan); Mori, Yoshihiro [Horiba Ltd., 2 Miyanohigashi, Kisshoin, Minami-ku, Kyoto 601-8510 (Japan); Shibata, Harumi [SUMCO Corporation, Seavance North, 1-2-1 Shibaura, Minato-ku, Tokyo 105-8634 (Japan); Shimazaki, Ayako [Toshiba Corporation, 8, Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); Shabani, Mohammad B. [Mitsubishi Material Corporation, 1-297, Kitabukuro-cho, Omiya-ku, Saitama 330-8508 (Japan); Yamagami, Motoyuki [Rigaku Corp., 14-8 Akaoji-cho, Takatsuki, Osaka 569-1146 (Japan); Yabumoto, Norikuni [Analysis Atelier Co., 4-36-4, Yoyogi, Shibuya-ku, Tokyo 151-0053 (Japan); Nishihagi, Kazuo [Horiba Ltd., 2 Miyanohigashi, Kisshoin, Minami-ku, Kyoto 601-8510 (Japan); Gohshi, Yohichi [Tsukuba University, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8571 (Japan)

    2013-12-01

    Vapor phase treatment (VPT) was under investigation by the International Organization for Standardization/Technical Committee 201/Working Group 2 (ISO/TC201/WG2) to improve the detection limit of total reflection X-ray fluorescence spectroscopy (TXRF) for trace metal analysis of silicon wafers. Round robin test results have confirmed that TXRF intensity increased by VPT for intentional contamination with 5 × 10{sup 9} and 5 × 10{sup 10} atoms/cm{sup 2} Fe and Ni. The magnification of intensity enhancement varied greatly (1.2–4.7 in VPT factor) among the participating laboratories, though reproducible results could be obtained for average of mapping measurement. SEM observation results showed that various features, sizes, and surface densities of particles formed on the wafer after VPT. The particle morphology seems to have some impact on the VPT efficiency. High resolution SEM observation revealed that a certain number of dots with SiO{sub 2}, silicate and/or carbon gathered to form a particle and heavy metals, Ni and Fe in this study were segregated on it. The amount and shape of the residue should be important to control VPT factor. - Highlights: • This paper presents a summary of study results of VPT–TXRF using ISO/TC201/WG2. • Our goal is to analyze the trace metallic contamination on silicon wafer with concentrations below 1 × 10{sup 10} atoms/cm{sup 2}. • The efficiency and mechanism of VPT are discussed under several round robin tests and systematic studies.

  8. Analysis of trace Fe in sea water by using inductively coupled plasma mass spectrometry with solid phase chelate extraction technique

    Field experiments on recovering from barren sea ground called 'Isoyake' by providing Fe in sea water to restore seaweed beds on barren ground, has been carried out. Fe supply source, a mixture of steelmaking slag and compost (humic wood chips), were laid underground in shoreline. A certain amount of restoration of seaweed beds has been confirmed at the locations for several years. Quantitative determination of trace amount of Fe in sea water in necessary to validate the effect of iron source. However, to analyze dissolved Fe in sea water was difficult due to its trace concentration and the interference by high concentration of salts in the analytical samples. We established new analysis method of Fe in sea water, by treating sea water with solid phase chelate extraction and analyzed by inductively coupled plasma mass spectrometry with cool plasma condition. This method was successfully applied for the sea water sample taken from experimental site. Other water quality parameters in the experimental site were also investigated. Fe concentration was significantly highest around the Fe supply source and was decreased with the distance. Although the concentrations of dissolved silica, Mg and Ca were correlated to electrical conductivity of the sample water, Fe concentration was not. According to those results, the concentration of dissolved Fe from steelmaking slag was confirmed, and Fe might be contiguously supplied to the sea water from Fe supply source and promoted the growth of seaweeds. Therefore, applying a mixture of steelmaking slag and compost as Fe supply source is an effective technique to supply dissolved iron to Isoyake area. (author)

  9. Tracing symmetries and their breakdown through phases of heterotic (2,2) compactifications

    Blaszczyk, Michael

    2015-01-01

    We are considering the class of heterotic $\\mathcal{N}=(2,2)$ Landau-Ginzburg orbifolds with 9 fields corresponding to $A_1^9$ Gepner models. We classify all of its Abelian discrete quotients and obtain 152 inequivalent models closed under mirror symmetry with $\\mathcal{N}=1,2$ and $4$ supersymmetry in 4D. We compute the full massless matter spectrum at the Fermat locus and find a universal relation satisfied by all models. In addition we give prescriptions of how to compute all quantum numbers of the 4D states including their discrete R-symmetries. Using mirror symmetry of rigid geometries we describe orbifold and smooth Calabi-Yau phases as deformations away from the Landau-Ginzburg Fermat locus in two explicit examples. We match the non-Fermat deformations to the 4D Higgs mechanism and study the conservation of R-symmetries. The first example is a $\\mathbb{Z}_3$ orbifold on an E$_6$ lattice where the R-symmetry is preserved. Due to a permutation symmetry of blow-up and torus K\\"{a}hler parameters the R-sym...

  10. A simple inexpensive gas phase chemiluminescence analyzer for measuring trace levels of arsenic in drinking water

    An inexpensive sensitive gas-phase chemiluminescence (GPCL) based analyzer for arsenic is described; this device utilizes manual fluid dispensing operations to reduce size, weight and cost. The analyzer in its present form has a limit of detection (LOD, S/N = 3) of 1.0 μg/L total inorganic As (peak heightbased, 3 mL sample). The system was used to measure low level arsenic in tap water samples from Texas and New Mexico and compared with results obtained by inductively coupled plasma-mass spectrometry (ICP-MS) as well as those from an automated GPCL analyzer. Good correlations were observed. Higher levels of As (50-500 μg/L, As(III), As(V) and mixtures thereof) were spiked into local tap water; the recoveries ranged from 95 ± 2% to 101 ± 1%. A single instrument weighs less than 3 kg, consumes <25 W in power, can be incorporated in a briefcase and constructed for <$US $1000. It is easily usable in the field. - An inexpensive instrument capable of measuring down to 1 μg/L As is reported.

  11. Development and validation of polymerized high internal phase emulsion monoliths coupled with HPLC and fluorescence detection for the determination of trace tetracycline antibiotics in environmental water samples.

    Du, Fuyou; Zheng, Xian; Sun, Lin; Qin, Qun; Guo, Lin; Ruan, Guihua

    2015-11-01

    A polymerized high internal phase emulsion monolith was used as a novel sorbent for solid-phase extraction coupled with high-performance liquid chromatography and fluorescence detection for the determination of oxytetracycline, tetracycline, doxycycline, and chlorotetracycline in environmental water samples. The polymerized high internal phase emulsion monolithic column was prepared by the in situ polymerization of the continuous phase of a high internal phase emulsion containing glycidyl methacrylate, styrene, and divinylbenzene in pipette tips, and then functionalized with iminodiacetic acid. The resulting monolith exhibited highly interconnected porosity and large surface areas, making it an excellent candidate as an solid-phase extraction sorbent for the enrichment of trace tetracycline antibiotics. Several factors affecting the extraction performance of polymerized high internal phase emulsion monoliths, including the pH of sample solution, the eluting solvents, the sample loading flow rate and volume, were investigated, respectively. Under the optimized conditions, the mean recoveries of oxytetracycline, tetracycline, doxycycline, and chlorotetracycline spiked in pond and farm wastewater samples ranged from 78.1 to 119.3% with relative standard deviation less than 15%. The detection limits (S/N = 3) of the proposed method were in the range of 51-137 pg/mL. This study demonstrated that the monolithic polymerized high internal phase emulsion would be promising solid-phase extraction sorbents in the extraction and proconcentration of trace analytes from complex samples. PMID:26331390

  12. Extraction and determination of trace amounts of chlorpromazine in biological fluids using magnetic solid phase extraction followed by HPLC

    Yadollah Yamini

    2014-08-01

    Full Text Available A simple, rapid and sensitive method termed as magnetic solid phase extraction (MSPE combined with high-performance liquid chromatography-ultraviolet detector (HPLC-UV has been proposed for the determination of trace amounts of chlorpromazine (CPZ in water, urine and plasma samples. The separation and determination was performed on a C18 column under the optimal chromatographic conditions. Several factors influencing the extraction efficiency of CPZ, such as pH, surfactant and adsorbent amounts, ionic strength, extraction time, sample volume and desorption conditions, were studied and optimized. Under the optimal MSPE conditions, the extraction percentage of CPZ was 74%, 27% and 16% in water, urine and plasma samples, respectively. The limits of detection (LODs of the proposed approach were 0.1, 5.0 and 10 ng/mL in water, urine and plasma samples, respectively. The relative standard deviations (RSDs based on five replicate determinations at 10 ng/mL level of CPZ was 1.2%. Good linear behaviors over the investigated concentration ranges (0.25–300 ng/mL with good coefficient of determination, R2>0.9998, were obtained. Good spike recoveries with relative errors less than 9.0% were obtained when applying the proposed method to water, urine and plasma samples.

  13. Multiple effects of trace elements on methanogenesis in a two-phase anaerobic membrane bioreactor treating starch wastewater.

    Yu, Dawei; Li, Chao; Wang, Lina; Zhang, Junya; Liu, Jing; Wei, Yuansong

    2016-08-01

    For enhancing anaerobic membrane bioreactor (AnMBR) treating food processing wastewater due to speed-limited methanogenesis step, multiple effects of trace element (TE) supplementation on methanogenesis of a two-phase AnMBR were firstly investigated in batch tests. TE supplementation included individual element, combination and recovery of Fe, Ni, Co, Cu and Zn supplementation. Multiple effects of TE supplementation were highest stimulated by 22.4 ± 5.6 % (TE313) for chemical oxygen demand (COD) removal, 43.1 ± 12.5 % (TE303) for specific methanogenic activity (SMA) and 13.9 ± 3.7 % (TE405) for biomass growth, respectively, although only 7.5 ± 0.6 % (TE106) for methane production. Dosage of TEs played a critical role in methane production, COD removal and biomass growth of the AnMBR's methanogenesis. Low dosages of TE supplementation improved the COD removal and slightly stimulated the COD bioconverting to methane and biomass, but their specific methanation activities were inhibited in the initial rapid methanogenesis stage. Several methanation functional species were increased in abundance like Methanosarcina and Methanoculleus. PMID:26879957

  14. Solid-phase extraction of trace Au(Ⅲ) with SDG and determination by the catalytic spectrophotometric method

    2008-01-01

    The new catalytic kinetic spectrophotometric method for Au(Ⅲ) determination was developed and validated.It was based on the catalytic effect of gold on the oxidation of sudan red Ⅲ by ammonium peroxodisulfate ((NH4)2S2O8) with nitrilo triaeetic acid as an activator in microemulsion and H2SO4 medium.Under optimum conditions,there was the linearity of the calibration curve in the concentration range from 0 to 20 μg/L Au(Ⅲ) at 520 nm.The relative standard deviation was 3.0% with a correlation coefficient of 0.9986.The detection limit achieved was 9.75×10-5 μg/mL.A new method using a column packed with sulfhydryl dextrose gel (SDG) as a solid-phase extraetant has been developed for the preeoncentration and separation of Au(Ⅲ) ions.The method has been applied to the determination of trace gold with satisfactory results.

  15. Kinetics as a tool to assess the immobilization of soil trace metals by binding phase amendments for in situ remediation purposes.

    Varrault, Gilles; Bermond, Alain

    2011-08-30

    Many soil remediation techniques consist in decreasing the mobility of trace metals by means of adding trace metal binding phases. For this study, whose aim is to assess the efficiency of soil remediation method by binding phase amendment, a kinetic fractionation method that provides the labile and slowly labile trace metal amounts in soil has been introduced. Manganese oxides (vernadite) and insolubilized humic acids (IHA) have been used as binding phases for the remediation of four heavily polluted soils. Vernadite amendments are effective for lead and cadmium remediation, whereas IHA amendments are only effective for copper remediation. In most cases, the labile metal fractions decrease dramatically in amended soils (up to 50%); on the other hand, the amounts of total extracted metal near the point of thermodynamic equilibrium often show no significant difference between the amended soil and the control soil. These results highlight the utility of kinetic fractionation in assessing the efficiency of soil remediation techniques and, more generally, in evaluating trace metal mobility in soils and its potential advantages compared to extraction schemes performed under equilibrium conditions. In the future, this kinetic method could be considerably simplified so as to consume much less time allowing its routine use. PMID:21708424

  16. Kinetics as a tool to assess the immobilization of soil trace metals by binding phase amendments for in situ remediation purposes

    Highlights: → Assessment of the efficiency of soil remediation method by binding phase amendment. → Use of a kinetic fractionation method to assess trace metal mobility in amended soils. → Vernadite amendments are effective for lead and cadmium remediation. → IHA amendments are only effective for copper remediation. → Advantages of kinetic fractionation vs. extraction schemes performed at equilibrium. - Abstract: Many soil remediation techniques consist in decreasing the mobility of trace metals by means of adding trace metal binding phases. For this study, whose aim is to assess the efficiency of soil remediation method by binding phase amendment, a kinetic fractionation method that provides the labile and slowly labile trace metal amounts in soil has been introduced. Manganese oxides (vernadite) and insolubilized humic acids (IHA) have been used as binding phases for the remediation of four heavily polluted soils. Vernadite amendments are effective for lead and cadmium remediation, whereas IHA amendments are only effective for copper remediation. In most cases, the labile metal fractions decrease dramatically in amended soils (up to 50%); on the other hand, the amounts of total extracted metal near the point of thermodynamic equilibrium often show no significant difference between the amended soil and the control soil. These results highlight the utility of kinetic fractionation in assessing the efficiency of soil remediation techniques and, more generally, in evaluating trace metal mobility in soils and its potential advantages compared to extraction schemes performed under equilibrium conditions. In the future, this kinetic method could be considerably simplified so as to consume much less time allowing its routine use.

  17. Phase transfer hollow fiber liquid phase microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of trace heavy metals in environmental and biological samples.

    Guo, Xueqin; He, Man; Chen, Beibei; Hu, Bin

    2012-11-15

    A new method of phase transfer hollow fiber liquid phase microextraction (PT-HF-LPME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) has been developed for the determination of trace Co, Pd, Cd and Bi in environmental and biological samples. In PT-HF-LPME, an intermediate solvent (1-butanol) was added into the sample solution to ensure the maximum contact area between the target metal ions and the chelating reagent (8-hydroxyquinoline, 8-HQ), which accelerated the formation of 8-HQ-metal complexes and their subsequent extraction by extraction solvent (toluene). The experimental parameters affecting the extraction efficiency of PT-HF-LPME for the target metals were studied by simplex optimization and orthogonal array design (OAD) experiments. Under the optimized conditions, the enrichment factors for Co, Pd, Cd and Bi were 110, 393, 121 and 111-fold, respectively, the limits of detection (LODs, 3σ) ranged from 3.7 to 8.3 ng L(-1). The relative standard deviations (RSDs, c=0.5 ng mL(-1), n=7) were 8.7, 6.2, 12.4 and 12.9% for Co, Pd, Cd and Bi, respectively. To validate the accuracy of the proposed method, two Certified Reference Materials of GSBZ50009-88 Environment Water and GBW09103 Human Urine were analyzed, and the results obtained for Cd were in good agreement with the certified values. Finally, the developed method was successfully applied to the analysis of Co, Pd, Cd and Bi in lake water and human urine samples. PMID:23158357

  18. On ultrahigh temperature crustal metamorphism:Phase equilibria, trace element thermometry, bulk composition, heat sources, timescales and tectonic settings

    David E. Kelsey; Martin Hand

    2015-01-01

    Ultrahigh temperature (UHT) metamorphism is the most thermally extreme form of regional crustal metamorphism, with temperatures exceeding 900 ?C. UHT crustal metamorphism is recognised in more than 50 localities globally in the metamorphic rock record and is accepted as‘normal’ in the spectrum of regional crustal processes. UHT metamorphism is typically identified on the basis of diagnostic mineral assemblages such as sapphirine þ quartz, orthopyroxene þ sillimanite ? quartz and osumilite in MgeAl-rich rock compositions, now usually coupled with pseudosection-based thermobarometry using internally-consistent thermodynamic data sets and/or Al-in-Orthopyroxene and ternary feldspar ther-mobarometry. Significant progress in the understanding of regional UHT metamorphism in recent years includes: (1) development of a ferric iron activityecomposition thermodynamic model for sapphirine, allowing phase diagram calculations for oxidised rock compositions;(2) quantification of UHT conditions via trace element thermometry, with Zr-in-rutile more commonly recording higher temperatures than Ti-in-zircon. Rutile is likely to be stable at peak UHT conditions whereas zircon may only grow as UHT rocks are cooling. In addition, the extent to which Zr diffuses out of rutile is controlled by chemical communication with zircon; (3) more fully recognising and utilising temperature-dependent thermal properties of the crust, and the possible range of heat sources causing metamorphism in geodynamic modelling studies; (4) recognising that crust partially melted either in a previous event or earlier in a long-duration event has greater capacity than fertile, unmelted crust to achieve UHT conditions due to the heat energy consumed by partial melting reactions;(5) more strongly linking UePb geochronological data from zircon and monazite to PeT points or path segments through using Y þ REE partitioning between accessory and major phases, as well as phase diagrams incorporating Zr and REE

  19. Simultaneous detection of trace metal ions in water by solid phase extraction spectroscopy combined with multivariate calibration

    Wang, Lei; Cao, Peng; Li, Wei; Tong, Peijin; Zhang, Xiaofang; Du, Yiping

    2016-04-01

    Solid Phase Extraction Spectroscopy (SPES) developed in this paper is a technique to measure spectrum directly on the solid phase material where the analytes are concentrated in SPE process. Membrane enrichment and UV-Visible spectroscopy were utilized to fulfill SPES, and multivariate calibration method of partial least squares (PLS) was used to simultaneously detect the concentrations of trace cobalt (II) and zinc (II) in water samples. The proposed method is simple, sensitive and selective. The complexes of analyte ions were collected on the cellulose acetate membranes via membrane filtration after the complexation reaction with 1-2-pyridylazo 2-naphthol (PAN). The spectra of the membranes which contained the complexes of metal ions and PAN were measured directly without eluting. The analytical conditions including pH, reaction time, sample volume, the amount of PAN, and flow rates were optimized. Nonionic surfactant Brij-30 was absorbed on the membranes prior to SPES to modify the membranes for improving the enrichment and spectrum measurement. The interference from other ions to the determination was investigated. Under the optimal condition, the absorbance was linearly related to the concentration at the range of 0.1-3.0 μg/L and 0.1-2.0 μg/L, with the correlation coefficients (R2) of 0.9977 and 0.9951 for Co (II) and Zn (II), respectively. The limits of detection were 0.066 μg/L for cobalt (II) and 0.104 μg/L for zinc (II). PLS regression with leave-one-out cross-validation was utilized to build models to detect cobalt (II) and zinc (II) in drinking water samples simultaneously. The correlation coefficient between ion concentration and spectrum of calibration set and independent prediction set were 1.0000 and 0.9974 for cobalt (II) and 1.0000 and 0.9956 for zinc (II). For cobalt (II) and zinc (II), the errors of the prediction set were in the range 0.0406-0.1353 μg/L and 0.0025-0.1884 μg/L.

  20. Flow-through solid-phase based optical sensor for the multisyringe flow injection trace determination of orthophosphate in waters with chemiluminescence detection

    Morais, Inês P. A.; Miró, Manuel; Manera, Matias; Estela, José Manuel; Cerdà, Víctor; Souto, M. Renata S.; Rangel, António O S S

    2004-01-01

    In this work, a novel flow-through solid-phase based chemiluminescence (CL) optical sensor is described for the trace determination of orthophosphate in waters exploiting the multisyringe flow injection analysis (MSFIA) concept with multicommutation. The proposed time-based injection flow system relies upon the in-line derivatisation of the analyte with ammonium molybdate in the presence of vanadate, and the transient immobilisation of the resulting heteropolyacid in a N-vinylpyrroli...

  1. An Approximate Treatment of Reflection Coefficient in the Phased Beam Tracing Method for the Simulation of Enclosed Sound Fields at Medium Frequencies

    Jeong, Cheol-Ho; Ih, Jeong-Guon; Rindel, Jens Holger

    2008-01-01

    surface and the complex wave number for describing the propagation characteristics. In this study, two types of approximate real reflection coefficients derived from the measured absorption coefficient were tested for a practical applicability. As a test example, pressure impulse responses and energy......The phased beam tracing method (PBTM) was suggested as a medium-frequency simulation technique for the calculation of impulse response, although main assumptions of geometric acoustics still hold. The phased method needs the reflection coefficient for characterizing the acoustic property of a...

  2. Development of high internal phase emulsion polymeric monoliths for highly efficient enrichment of trace polycyclic aromatic hydrocarbons from large-volume water samples.

    Su, Rihui; Ruan, Guihua; Nie, Honggang; Xie, Ting; Zheng, Yanjie; Du, Fuyou; Li, Jianping

    2015-07-31

    In this work, polymerized high internal phase emulsion (polyHIPE) monoliths were prepared and applied as monolithic adsorbent materials for proconcentration of trace polycyclic aromatic hydrocarbons (PAHs) from large-volume water samples. The monolithic polyHIPE columns were prepared by in situ polymerization of the continuous phase of a high internal phase emulsion (HIPE) containing styrene (STY), divinylbenzene (DVB) and glycidyl methacrylate (GMA) in pipette tips, and the resulting STY/DVB/GMA polyHIPE monoliths exhibited highly interconnected porosity and large surface areas, making them excellent candidates as adsorbents for enrichment of trace aromatic compounds. The prepared STY/DVB/GMA polyHIPE monoliths were applied to the determination of trace PAHs in environmental water samples by combing with high performance liquid chromatography-fluorescence detection (HPLC-FLD). Under the optimized experimental conditions, the polyHIPE monoliths could effectively enrich trace 13 PAHs from 500mL of water samples, the mean recoveries at four spiked levels were ranged from 80.7% to 115.0% with the relative standard deviations (RSDs) lower than 14%, and the detection limits (LODs) were ranged from 4.0 to 228pg/L. In addition, the prepared polyHIPE monolith was stable enough for more than 200 replicate extraction cycles without measurable loss of performance on the enrichment of PAHs, and good column-to-column repeatability was obtained with RSD less than 13%. The proposed method was applied to simultaneous analysis of 13 PAHs in water samples with satisfactory recoveries. PMID:26077972

  3. Study of Stationary Phase Metabolism Via Isotopomer Analysis of Amino Acids from an Isolated Protein

    Shaikh, AfshanS.; Tang, YinjieJ.; Mukhopadhyay, Aindrila; Martin, Hector Garcia; Gin, Jennifer; Benke, Peter; Keasling, Jay D.

    2009-09-14

    Microbial production of many commercially important secondary metabolites occurs during stationary phase, and methods to measure metabolic flux during this growth phase would be valuable. Metabolic flux analysis is often based on isotopomer information from proteinogenic amino acids. As such, flux analysis primarily reflects the metabolism pertinent to the growth phase during which most proteins are synthesized. To investigate central metabolism and amino acids synthesis activity during stationary phase, addition of fully 13C-labeled glucose followed by induction of green fluorescent protein (GFP) expression during stationary phase was used. Our results indicate that Escherichia coli was able to produce new proteins (i.e., GFP) in the stationary phase, and the amino acids in GFP were mostly from degraded proteins synthesized during the exponential growth phase. Among amino acid biosynthetic pathways, only those for serine, alanine, glutamate/glutamine, and aspartate/asparagine had significant activity during the stationary phase.

  4. Novel ion imprinted magnetic mesoporous silica for selective magnetic solid phase extraction of trace Cd followed by graphite furnace atomic absorption spectrometry detection

    Zhao, Bingshan; He, Man; Chen, Beibei; Hu, Bin, E-mail: binhu@whu.edu.cn

    2015-05-01

    Determination of trace Cd in environmental, biological and food samples is of great significance to toxicological research and environmental pollution monitoring. While the direct determination of Cd in real-world samples is difficult due to its low concentration and the complex matrix. Herein, a novel Cd(II)-ion imprinted magnetic mesoporous silica (Cd(II)-II-MMS) was prepared and was employed as a selective magnetic solid-phase extraction (MSPE) material for extraction of trace Cd in real-world samples followed by graphite furnace atomic absorption spectrometry (GFAAS) detection. Under the optimized conditions, the detection limit of the proposed method was 6.1 ng L{sup −1} for Cd with the relative standard deviation (RSD) of 4.0% (c = 50 ng L{sup −1}, n = 7), and the enrichment factor was 50-fold. To validate the proposed method, Certified Reference Materials of GSBZ 50009–88 environmental water, ZK018-1 lyophilized human urine and NIES10-b rice flour were analyzed and the determined values were in a good agreement with the certified values. The proposed method exhibited a robust anti-interference ability due to the good selectivity of Cd(II)-II-MMS toward Cd(II). It was successfully employed for the determination of trace Cd(II) in environmental water, human urine and rice samples with recoveries of 89.3–116%, demonstrating that the proposed method has good application potential in real world samples with complex matrix. - Highlights: • Novel Cd(II)-II-MMS was prepared by surface imprinting combined with a sol–gel process. • Cd(II)-II-MMS has a high selectivity and adsorption capacity for Cd(II). • A sensitive and selective method of Cd(II)-IIMSPE-GFAAS was developed for trace cadmium analysis. • The method can be applied to determine trace Cd in various samples with complicated matrix.

  5. Novel ion imprinted magnetic mesoporous silica for selective magnetic solid phase extraction of trace Cd followed by graphite furnace atomic absorption spectrometry detection

    Determination of trace Cd in environmental, biological and food samples is of great significance to toxicological research and environmental pollution monitoring. While the direct determination of Cd in real-world samples is difficult due to its low concentration and the complex matrix. Herein, a novel Cd(II)-ion imprinted magnetic mesoporous silica (Cd(II)-II-MMS) was prepared and was employed as a selective magnetic solid-phase extraction (MSPE) material for extraction of trace Cd in real-world samples followed by graphite furnace atomic absorption spectrometry (GFAAS) detection. Under the optimized conditions, the detection limit of the proposed method was 6.1 ng L−1 for Cd with the relative standard deviation (RSD) of 4.0% (c = 50 ng L−1, n = 7), and the enrichment factor was 50-fold. To validate the proposed method, Certified Reference Materials of GSBZ 50009–88 environmental water, ZK018-1 lyophilized human urine and NIES10-b rice flour were analyzed and the determined values were in a good agreement with the certified values. The proposed method exhibited a robust anti-interference ability due to the good selectivity of Cd(II)-II-MMS toward Cd(II). It was successfully employed for the determination of trace Cd(II) in environmental water, human urine and rice samples with recoveries of 89.3–116%, demonstrating that the proposed method has good application potential in real world samples with complex matrix. - Highlights: • Novel Cd(II)-II-MMS was prepared by surface imprinting combined with a sol–gel process. • Cd(II)-II-MMS has a high selectivity and adsorption capacity for Cd(II). • A sensitive and selective method of Cd(II)-IIMSPE-GFAAS was developed for trace cadmium analysis. • The method can be applied to determine trace Cd in various samples with complicated matrix

  6. Trace element-bearing phases during the solid transport: in-situ characterization and temporal variability in the Loire bed-sediments (France)

    Grosbois, Cécile; Courtin-Nomade, Alexandra; Dhivert, Elie; Desmet, Marc; Kunz, Martin

    2013-04-01

    As a result of increased of agriculture, land use, urban areas, industry, traffic and population density, trace element inputs have altered considerably fluvial system (sediment, water quality and biota). The Loire River Basin (117,800 km2, total population of 8.4 Mp in 2010), even if it is considered one of the least human-impacted hydrosystem among the 5 large French basins, has been exposed to multiple sources of metals during the last 150 years, originating from major mining districts (coal and non-ferrous metals) and their associated industrial activities (Grosbois et al, 2012; Dhivert et al, 2013). Two major contamination periods were recorded in several core sediments throughout the basin: urban development of the basin. The limited dilution by detrital material (Loire sediment load between1.5 and 3.5 Mt/y) was an additional cause of such severe contamination. After 1950, river eutrophication was well-marked by the general increase of endogenic calcite in the mid and downstream part of the basin, slightly diluting all major and trace element bulk concentrations by 20% (Grosbois et al, 2012). Since 1980, a generalized and gradual decontamination of bed sediments started while mines were gradually closing, urban waste waters collected and treated in addition to new environmental regulations. They aim to limit metallic pollutant dispersion like industrial recycling of metal wastes and to reduce atmospheric emissions and consequently atmospheric fall out wet and dry deposition In-situ chemical and mineralogical techniques (EPMA, SEM-EDS/ACC system and synchrotron based µXRD) were used (i) to highlight anthropogenic activities by a specific mineralogical signature and (ii) to determine potential effects of post-depositional remobilization and access trace element mobility during the solid transport. Trace element-bearing phases were identified at a micron scale during both solid transport. However, some others also reflect post-depositional mechanisms like

  7. Simultaneous separation/enrichment and detection of trace ciprofloxacin and lomefloxacin in food samples using thermosensitive smart polymers aqueous two-phase flotation system combined with HPLC.

    Lu, Yang; Chen, Bo; Yu, Miao; Han, Juan; Wang, Yun; Tan, Zhenjiang; Yan, Yongsheng

    2016-11-01

    Smart polymer aqueous two phase flotation system (SPATPF) is a new separation and enrichment technology that integrated the advantages of the three technologies, i.e., aqueous two phase system, smart polymer and flotation sublation. Ethylene oxide and propylene oxide copolymer (EOPO)-(NH4)2SO4 SPATPF is a pretreatment technique, and it is coupled with high-performance liquid chromatography to analyze the trace ciprofloxacin and lomefloxacin in real food samples. The optimized conditions of experiment were determined in the multi-factor experiment by using response surface methodology. The flotation efficiency of lomefloxacin and ciprofloxacin was 94.50% and 98.23% under the optimized conditions. The recycling experimentsshowed that the smart polymer EOPO could use repeatedly, which will reduce the cost in the future application. PMID:27211613

  8. Interpretation of trace element and isotope features of basalts: relevance of field relations, petrology, major element data, phase equilibria, and magma chamber modeling in basalt petrogenesis

    O'Hara, M. J.; Herzberg, C.

    2002-06-01

    The concentrations and ratios of the major elements determine the physical properties and the phase equilibria behavior of peridotites and basalts in response to the changing energy contents of the systems. The behavior of the trace elements and isotopic features are influenced in their turn by the phase equilibria, by the physical character of the partial melting and partial crystallization processes, and by the way in which a magma interacts with its wall rocks. Concentrating on the trace element and isotope contents of basalts to the exclusion of the field relations, petrology, major element data, and phase equilibria is as improvident as slaughtering the buffalo for the sake of its tongue. The crust is a cool boundary layer and a density filter, which impedes the upward transfer of hot, dense "primary" picritic and komatiitic liquids. Planetary crusts are sites of large-scale contamination and extensive partial crystallization of primitive melts striving to escape to the surface. Escape of truly unmodified primitive melts to the surface is a rare event, requiring the resolution of daunting problems in chemical and mechanical engineering. Primary status for volumetrically abundant basalts such as mid-ocean ridge basalt, ocean island basalt, and continental flood basalts is denied by their low-pressure cotectic character, first remarked upon on petrological grounds in 1928 and on experimental grounds in 1962. These basalt liquids are products of crystal-liquid separation at low pressure. Primary status for these common basalts is further denied by the phase equilibria of such compositions at elevated pressures, when the required residual mantle mineralogy (magnesian olivine and orthopyroxene) is not stable at the liquidus. It is also denied by the picritic or komatiitic nature of partial melts of candidate upper-mantle compositions at high pressures - a conclusion supported by calculation of the melt composition, which would need to be extracted in order to

  9. 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.

    Du, Fuyou; Sun, Lin; Zhen, Xian; Nie, Honggang; Zheng, Yanjie; Ruan, Guihua; Li, Jianping

    2015-08-01

    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 %. PMID:26025552

  10. Solid phase extraction and trace monitoring of cadmium ions in environmental water and food samples based on modified magnetic nanoporous silica

    Omidi, Fariborz [Department of Occupational Health Engineering, School of Public Health, Shahroud University of Medical Sciences, Shahroud (Iran, Islamic Republic of); Behbahani, Mohammad, E-mail: mohammadbehbahai89@yahoo.com [Department of Chemistry, Shahid Beheshti University, Evin, Tehran (Iran, Islamic Republic of); Kalate Bojdi, Majid [Faculty of Chemistry, Kharazmi (Tarbiat Moallem) University, Tehran (Iran, Islamic Republic of); Shahtaheri, Seyed Jamaleddin [Department of Occupational Health Engineering, School of Public Health and Institute for Environmental Research, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2015-12-01

    A new method has been developed for trace separation/preconcentration of cadmium ions using pyridine-functionalized magnetic nanoporous silica material (called Py-Fe{sub 3}O{sub 4}@MCM-41) as a new magnetic sorbent and their determination by flame atomic absorption spectrometry (FAAS). The Py-Fe{sub 3}O{sub 4}@MCM-41 sorbent was characterized by thermogravimetric analysis, differential thermal analysis, transmission electron microscopy, Fourier transform infrared spectrometry and X-ray diffraction. The modified Fe{sub 3}O{sub 4}@MCM-41 can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, amount of functionalized Fe{sub 3}O{sub 4}@MCM-41, extraction time, type and quantity of eluent, desorption time, and interfering ions on the extraction efficiency were evaluated and optimized. Under the optimized conditions, the detection limit and relative standard deviation was 0.04 μg L{sup –1} and 2.9%, respectively and the maximum adsorption capacity of the synthesized sorbent for cadmium ions was 154 mg g{sup −1}. The proposed method has been applied to the determination of Cd ions at trace levels in real samples such as, rice, onion, carrot, lettuce, parsley, basil, tap water, river water and seawater with satisfactory results. - Highlights: • The introducing of modified magnetic mesoporous silica as a novel magnetic sorbent. • Trace monitoring of cadmium ions. • The limit of detection (LOD) by the proposed solid phase extraction method was 0.04 ng mL{sup −1} for the cadmium ions. • High surface areas and magnetic characteristic of the sorbent. • Maximum adsorption capacity of the sorbent was 154 mg g{sup −1}.

  11. Solid phase extraction and trace monitoring of cadmium ions in environmental water and food samples based on modified magnetic nanoporous silica

    A new method has been developed for trace separation/preconcentration of cadmium ions using pyridine-functionalized magnetic nanoporous silica material (called Py-Fe3O4@MCM-41) as a new magnetic sorbent and their determination by flame atomic absorption spectrometry (FAAS). The Py-Fe3O4@MCM-41 sorbent was characterized by thermogravimetric analysis, differential thermal analysis, transmission electron microscopy, Fourier transform infrared spectrometry and X-ray diffraction. The modified Fe3O4@MCM-41 can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, amount of functionalized Fe3O4@MCM-41, extraction time, type and quantity of eluent, desorption time, and interfering ions on the extraction efficiency were evaluated and optimized. Under the optimized conditions, the detection limit and relative standard deviation was 0.04 μg L–1 and 2.9%, respectively and the maximum adsorption capacity of the synthesized sorbent for cadmium ions was 154 mg g−1. The proposed method has been applied to the determination of Cd ions at trace levels in real samples such as, rice, onion, carrot, lettuce, parsley, basil, tap water, river water and seawater with satisfactory results. - Highlights: • The introducing of modified magnetic mesoporous silica as a novel magnetic sorbent. • Trace monitoring of cadmium ions. • The limit of detection (LOD) by the proposed solid phase extraction method was 0.04 ng mL−1 for the cadmium ions. • High surface areas and magnetic characteristic of the sorbent. • Maximum adsorption capacity of the sorbent was 154 mg g−1

  12. Reduced mitochondrial malate dehydrogenase activity has a strong effect on photorespiratory metabolism as revealed by 13C labelling.

    Lindén, Pernilla; Keech, Olivier; Stenlund, Hans; Gardeström, Per; Moritz, Thomas

    2016-05-01

    Mitochondrial malate dehydrogenase (mMDH) catalyses the interconversion of malate and oxaloacetate (OAA) in the tricarboxylic acid (TCA) cycle. Its activity is important for redox control of the mitochondrial matrix, through which it may participate in regulation of TCA cycle turnover. In Arabidopsis, there are two isoforms of mMDH. Here, we investigated to which extent the lack of the major isoform, mMDH1 accounting for about 60% of the activity, affected leaf metabolism. In air, rosettes of mmdh1 plants were only slightly smaller than wild type plants although the fresh weight was decreased by about 50%. In low CO2 the difference was much bigger, with mutant plants accumulating only 14% of fresh weight as compared to wild type. To investigate the metabolic background to the differences in growth, we developed a (13)CO2 labelling method, using a custom-built chamber that enabled simultaneous treatment of sets of plants under controlled conditions. The metabolic profiles were analysed by gas- and liquid- chromatography coupled to mass spectrometry to investigate the metabolic adjustments between wild type and mmdh1 The genotypes responded similarly to high CO2 treatment both with respect to metabolite pools and (13)C incorporation during a 2-h treatment. However, under low CO2 several metabolites differed between the two genotypes and, interestingly most of these were closely associated with photorespiration. We found that while the glycine/serine ratio increased, a concomitant altered glutamine/glutamate/α-ketoglutarate relation occurred. Taken together, our results indicate that adequate mMDH activity is essential to shuttle reductants out from the mitochondria to support the photorespiratory flux, and strengthen the idea that photorespiration is tightly intertwined with peripheral metabolic reactions. PMID:26889011

  13. Short, synthetic and selectively 13C-labeled RNA sequences for the NMR structure determination of protein–RNA complexes

    Wenter, Philipp; Reymond, Luc; Auweter, Sigrid D.; Allain, Frédéric H.-T.; Pitsch, Stefan

    2006-01-01

    We report an optimized synthesis of all canonical 2′-O-TOM protected ribonucleoside phosphoramidites and solid supports containing [13C5]-labeled ribose moieties, their sequence-specific introduction into very short RNA sequences and their use for the structure determination of two protein–RNA complexes. These specifically labeled sequences facilitate RNA resonance assignments and are essential to assign a high number of sugar–sugar and intermolecular NOEs, which ultimately improve the precis...

  14. Monitoring CO[subscript 2] Fixation Using GC-MS Detection of a [superscript 13]C-Label

    Hammond, Daniel G.; Bridgham, April; Reichert, Kara; Magers, Martin

    2010-01-01

    Much of our understanding of metabolic pathways has resulted from the use of chemical and isotopic labels. In this experiment, a heavy isotope of carbon, [superscript 13]C, is used to label the product of the well-known RuBisCO enzymatic reaction. This is a key reaction in photosynthesis that converts inorganic carbon to organic carbon; a process…

  15. HCCCH Experiment for Through-Bond Correlation of Thymine Resonances in 13C-Labeled DNA Oligonucleotides

    Sklenář, Vladimír.; Masse, James E.; Feigon, Juli

    1999-04-01

    Application of heteronuclear magnetic resonance pulse methods to13C,15N-labeled nucleic acids is important for the accurate structure determination of larger RNA and DNA oligonucleotides and protein-nucleic acid complexes. These methods have been applied primarily to RNA, due to the availability of labeled samples. The two major differences between DNA and RNA are at the C2‧ of the ribose and deoxyribose and the additional methyl group on thymine versus uracil. We have enzymatically synthesized a13C,15N-labeled 32 base DNA oligonucleotide that folds to form an intramolecular triplex. We present two- and three-dimensional versions of a new HCCCH-TOCSY experiment that provides intraresidue correlation between the thymine H6 and methyl resonances via the intervening carbons (H6-C6-C5-Cme-Hme).

  16. 13C-labeled 18 : 2n-6 recovered in brush border membrane phospholipids short time after administration

    Vistisen, Bodil; Høy, Carl-Erik

    2004-01-01

    administered intragastrically a bolus of ML*M, M*LM*, L*L*L* or M*M*M* (* = C-13- labeled fatty acid). Rats were decapitated 2 hours and 6 hours later, and the fatty acid composition and C-13-enrichment of BBM-PC and -PE were determined. C-13-enriched 18:2n-6 was observed in BBM-PC after intragastric...... administration of L*L*L* and ML*M, whereas no C-13-labeled fatty acids were recovered after administration of M*LM* or M*M*M*. Interestingly, no C-13-labeled fatty acids were detected in the BBM-PE fraction. This could be due to a lower turnover of PE than PC and to a different ratio of saturated and unsaturated...... fatty acids in the two phospholipid pools. Minor effects on BBM-PC and BBM-PE fatty acid profiles (mole-%) were observed. The present study demonstrated for the first time incorporation of C-13-labeled 18:2n-6 into BBM-PC 2 hours and 6 hours after intragastric administration of L*L*L* or ML*M. This...

  17. Direct uptake of organic carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence

    Alexandre, A.; Balesdent, J.; Cazevieille, P.; Chevassus-Rosset, C.; Signoret, P.; Mazur, J.-C.; Harutyunyan, A.; Doelsch, E.; Basile-Doelsch, I.; Miche, H.; Santos, G. M.

    2015-12-01

    In the rhizosphere, the uptake of low molecular weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relatively to total uptake is important, organic C uptake is supposed to be low relatively to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and in which extent organic C absorbed by grass roots, under the form of either intact amino acids (AAs) or microbial metabolites, can feed the organic C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled AAs to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C-excess and 15N-excess) in the roots, stems and leaves, and phytoliths, as well as the 13C-excess in AAs extracted from roots and stems and leaves, were quantified relatively to a control experiment in which no labelled AAs were added. The net uptake of 13C derived from the labeled AAs supplied to the nutritive solution (AA-13C) by Festuca arundinacea represented 4.5 % of the total AA-13C supply. AA-13C fixed in the plant represented only 0.13 % of total C. However, the experimental conditions may have underestimated the extent of the process under natural and field conditions. Previous studies showed that 15N and 13C can be absorbed by the roots in several organic and inorganic forms. In the present experiment, the fact that phenylalanine and methionine, that were supplied in high amount to the nutritive solution, were more 13C-enriched than other AAs in the roots and stems and leaves strongly suggested that part of AA-13C was absorbed and translocated in its original AA form. The concentration of AA-13C represented only 0.15 % of the phytolith C (phytC) but was still 1.5 times higher in phytoliths than in leaves supporting that, ultimately, AA-13C was preferentially fixed in organic compounds subject to occlusion in phytoliths. Plausible forms of AA-13C and AA-15N absorbed and translocated, AA-13C fixation in phytoliths and implication of our finding for our understanding of the C cycle at the plant-soil interface are discussed.

  18. Direct uptake of organically derived carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence

    Alexandre, Anne; Balesdent, Jérôme; Cazevieille, Patrick; Chevassus-Rosset, Claire; Signoret, Patrick; Mazur, Jean-Charles; Harutyunyan, Araks; Doelsch, Emmanuel; Basile-Doelsch, Isabelle; Miche, Hélène; Santos, Guaciara M.

    2016-03-01

    In the rhizosphere, the uptake of low-molecular-weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relative to total uptake is important, organic C uptake is supposed to be low relative to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and to what extent organically derived C absorbed by grass roots can feed the C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled amino acids (AAs) to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C excess and 15N excess) in the roots, stems and leaves as well as phytoliths were measured relative to a control experiment in which no labeled AAs were added. Additionally, the 13C excess was measured at the molecular level, in AAs extracted from roots and stems and leaves. The net uptake of labeled AA-derived 13C reached 4.5 % of the total AA 13C supply. The amount of AA-derived 13C fixed in the plant was minor but not nil (0.28 and 0.10 % of total C in roots and stems/leaves, respectively). Phenylalanine and methionine that were supplied in high amounts to the nutritive solution were more 13C-enriched than other AAs in the plant. This strongly suggested that part of AA-derived 13C was absorbed and translocated into the plant in its original AA form. In phytoliths, AA-derived 13C was detected. Its concentration was on the same order of magnitude as in bulk stems and leaves (0.15 % of the phytolith C). This finding strengthens the body of evidences showing that part of organic compounds occluded in phytoliths can be fed by C entering the plant through the roots. Although this experiment was done in nutrient solution and its relevance for soil C uptake assessment is therefore limited, we discuss plausible forms of AA-derived 13C absorbed and translocated in the plant and eventually fixed in phytoliths, and implications of our results for our understanding of the C cycle at the soil-plant-atmosphere interface

  19. Selective {sup 2}H and {sup 13}C labeling in NMR analysis of solution protein structure and dynamics

    LeMaster, D.M. [Northwestern Univ., Evanston, IL (United States)

    1994-12-01

    Preparation of samples bearing combined isotope enrichment patterns has played a central role in the recent advances in NMR analysis of proteins in solution. In particular, uniform {sup 13}C, {sup 15}N enrichment has made it possible to apply heteronuclear multidimensional correlation experiments for the mainchain assignments of proteins larger than 30 KDa. In contrast, selective labeling approaches can offer advantages in terms of the directedness of the information provided, such as chirality and residue type assignments, as well as through enhancements in resolution and sensitivity that result from editing the spectral complexity, the relaxation pathways and the scalar coupling networks. In addition, the combination of selective {sup 13}C and {sup 2}H enrichment can greatly facilitate the determination of heteronuclear relaxation behavior.

  20. Quantification of peptide m/z distributions from 13C-labeled cultures with high resolution mass spectrometry

    With the introduction of orbital trap mass spectrometers molecular masses can be determined with great precision and accuracy. In addition, orbital trap spectrometers (Orbitraps) are sensitive and possess a linear dynamic range of multiple orders of magnitude. These qualities make the Orbitrap well-...

  1. Phase equilibria constraints on liquid lines of descent generated by paired assimilation and fractional crystallization: Trace elements and Sr and Nd isotopes

    Utilizing a phase equilibria based trace element isotope model for low pressure igneous differentiation, it is now possible to update the methods presently being used to evaluate the effect of assimilation and fractional crystallization (AFC) processes. The results of the calculations presented here indicate that bulk partition coefficients (D) for Sr and Nd are strongly dependent on the chemistry of the assimilants will increase bulk D for network-modifying cations because of the positive correlation of most trace element partition coefficients with reciprocal temperature, and the amount of network forming components in the melt. In addition to the effect of temperature and melt composition, the addition of a magma of different composition from the magma chamber will generally cause a change in the fractionating mineral proportions. For example, a peraluminous assimilant will increase the proportion of plagioclase, and a peralkaline assimilant will increase the proportion of augite. This will in turn have an effect on bulk D. For most multiply saturated mafic to intermediate systems differentiating at low pressure, bulk DSr is >1, and bulk DNd is Sr away from 1 and a peralkaline assimilant drives bulk DNd toward 1. Compared to the results derived in this study, existing models using fixed bulk Ds calculated from closed system conditions will generate results that underestimate the assimilation rate, 87/86Sr and bulk Sr content for a peraluminous assimilant, and over-estimate the assimilation rate, 143/144Nd and Nd content of the assimilant for a peralkaline assimilant

  2. Impregnated multiwalled carbon nanotubes as efficient sorbent for the solid phase extraction of trace amounts of heavy metal ions in food and water samples.

    Gouda, Ayman A; Al Ghannam, Sheikha M

    2016-07-01

    A new, sensitive and simple solid phase extraction (SPE), separation and preconcentration method of some heavy metal ions, Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) at trace levels using multiwalled carbon nanotubes (MWCNTs) impregnated with 2-(2-benzothiazolylazo)orcinol (BTAO) from food and water samples were investigated. The effect of analytical parameters was examined. The metals retained on the nanotubes at pH 7.0 were eluted by 5.0mL HNO3 (2.0molL(-1)). The influence of matrix ions on the proposed method was evaluated. The preconcentration factor was calculated and found to be 100. The detection limits (LODs) for Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) were found at 0.70, 1.2, 0.80, 2.6 and 2.2μgL(-1), respectively. The relative standard deviation (RSD) and the recoveries of the standard addition method were lower than 5.0% and 95-102%, respectively. The new procedure was successfully applied to the determination of trace amounts of the studied metal ions in various food and water samples and validated using certified reference materials SRM 1570A (spinach leaves) with satisfactory and compatible results. PMID:26920312

  3. Displacement solid-phase extraction on mercapto-functionalized magnetite microspheres for inductively coupled plasma mass spectrometric determination of trace noble metals

    A flow injection online displacement solid-phase extraction (DSPE) via magnetic immobilization of mercapto-functionalized magnetite microspheres onto the inner walls of a knotted reactor (KR) coupled with inductively coupled plasma mass spectrometry was developed for selective preconcentration and determination of trace noble metals (Ru, Rh, Pd, Pt, Ir and Au) in complex matrices. Online DSPE of 2.7 mL aqueous solution gave the enhancement factors of 32-46 for the six noble metals in comparison with direct nebulization of aqueous sample solution, and the detection limits (3 s) of 2.1 ng L-1 for Ru, 1.9 ng L-1 for Rh, 2.5 ng L-1 for Pd, 1.8 ng L-1 for Ir, 1.9 ng L-1 for Pt and 1.7 ng L-1 for Au. The sample throughput of the developed method was about 20 samples h-1, and the relative standard deviation for eleven replicate determinations of the noble metals at the 30 ng L-1 level ranged from 1.2% to 2.1%. The recoveries of Ru, Rh, Pd, Pt, Ir and Au still maintained 90% even after successive 140 cycles of DSPE. The developed method was successfully applied to selective determination of trace Ru, Rh, Pd, Pt, Ir and Au in complex matrices.

  4. Overview of the trace gas measurements on board the Citation aircraft during the intensive field phase of INDOEX

    de Gouw, JA; Warneke, C; Scheeren, HA; van der Veen, C; Bolder, M; Scheele, MP; Williams, J; Wong, S; Lange, L; Fischer, H; Lelieveld, J

    2001-01-01

    During the intensive field phase of the Indian Ocean Experiment (INDOEX), measurements of the atmospheric chemical and aerosol composition over the Indian Ocean were performed from a Cessna Citation aircraft. Measurements were performed during February and March 1999 over the northern Indian Ocean f

  5. Solid Phase Extraction of Trace Copper(Ⅱ) Using Octadecyl Silica Membrane Disks Modified with N,N'-DisalicyJideneethylenediamine

    MOGHIMI Ali

    2007-01-01

    A simple and reproducible method for the rapid extraction and determination of trace amounts of copper(Ⅱ)ions using octadecyl-bonded silica membrane disks modified by N,N'-disalicylideneethylenediamine (DESDA) and atomic absorption spectrometry was presented.The method is based on complex formation on the surface of the ENVI-18 DISKTM disks followed by stripping of the retained species by minimum amounts of appropriate organic solvents.The elution is efficient and quantitative.The effects of potential interfering ions,pH,ligand amount,stripping solvent,and sample flow rate were also investigated.Under the optimal experimental conditions,the break-through volume was found to about be 1000 mL providing a preconcentration factor of 500.The maximum capacity of the disks was found to be (389±4) μg for Cu2+.The limit of detection of the proposed method is 5 ng per liter.The method was applied to the extraction and recovery of copper in different water samples.

  6. APASVO: A free software tool for automatic P-phase picking and event detection in seismic traces

    Romero, José Emilio; Titos, Manuel; Bueno, Ángel; Álvarez, Isaac; García, Luz; Torre, Ángel de la; Benítez, M.a. Carmen

    2016-05-01

    The accurate estimation of the arrival time of seismic waves or picking is a problem of major interest in seismic research given its relevance in many seismological applications, such as earthquake source location and active seismic tomography. In the last decades, several automatic picking methods have been proposed with the ultimate goal of implementing picking algorithms whose results are comparable to those obtained by manual picking. In order to facilitate the use of these automated methods in the analysis of seismic traces, this paper presents a new free, open source, software graphical tool, named APASVO, which allows picking tasks in an easy and user-friendly way. The tool also provides event detection functionality, where a relatively imprecise estimation of the onset time is sufficient. The application implements the STA-LTA detection algorithm and the AMPA picking algorithm. An autoregressive AIC-based picking method can also be applied. Besides, this graphical tool is complemented with two additional command line tools, an event picking tool and a synthetic earthquake generator. APASVO is a multiplatform tool that works on Windows, Linux and OS X. The application can process data in a large variety of file formats. It is implemented in Python and relies on well-known scientific computing packages such as ObsPy, NumPy, SciPy and Matplotlib.

  7. Solid phase extraction of ultra trace amounts of Nickel (II) using Schiff's base AImmobilized on SDS-coated Alumina

    The purpose of this research was introducing a new sorbent for preconcentration of nickel ion from aqueous sample solution. Sodium dodecy sulfate, as a surfactant, makes ad micelle on the surface of substrate, γ-alumina. This allows the metal complexing agent, Schiff's A, to be immobilized in to hydrocarbon cores of the ad micelles. This assemble, as a chelating sorbent, has made the separation and preconcentration of nickel ion possible. In the present work, a column of alumina modified with sodium dodecyl sulfate and Schiff's base A was prepared for the preconcentration of trace nickel from water samples for a flame atomic absorption spectroscopy determination under the optimized conditions. (p H=6.5 flow rate, 30 ml/min) nickel (II) was retained on the column. The nickel collected on the column was eluted with 5 ml of 1 M nitric acid. Recovery was greater than 98%. A concentration factor of 200 can be achieved by passing 1000 ml of sample through the column. The relative standard deviation (10 replicate analysis) at the 100 ng ml1 level for nickel was 2.4% and the corresponding limit of detection (based on 30) was 0.03 ngm1. The method was applied to the determination of nickel in wasted and mineral waters

  8. Determination of trace total inorganic arsenic by hydride generation atomic fluorescence spectrometry after solid phase extraction-preconcentration on aluminium hydroxide gel

    We describe a simple, effective, inexpensive and rapid method for the determination of trace amounts of total inorganic arsenic in water samples by means of a modified solid phase preconcentration procedure using an aluminium hydroxide gel sorbent and hydride generation atomic fluorescence spectrometry (HGAFS). This method avoids the traditional extraction procedures that are time- and solvent-consuming. The effects of quantity of adsorbent, solution pH, adsorption time and potentially interfering ions were studied. Under the optimal conditions, the detection limit is 3 ng.L-1, and the enrichment factor is 167. The calibration plot is linear in the range from 0.05 to 10 μg.L-1, with a correlation coefficient of 0.9992. The relative standard deviation (RSD) was less than 6.1 % (n = 5) and recoveries in spiked environmental water were >100 %. The method was successfully applied to the determination of total inorganic arsenic in natural water samples. (author)

  9. Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes

    C. L. Fern

    2007-02-01

    Full Text Available The wave packets of atmospheric gravity waves were numerically generated, with a given characteristic wave period, horizontal wave length and projection mean wind along the horizontal wave vector. Their projection phase and group velocities along the oblique radar beam (vpr and vgr, with different zenith angle θ and azimuth angle φ, were analyzed by the method of phase- and group-velocity tracing. The results were consistent with the theoretical calculations derived by the dispersion relation, reconfirming the accuracy of the method of analysis. The RTI plot of the numerical wave packets were similar to the striation patterns of the QP echoes from the FAI irregularity region. We propose that the striation range rate of the QP echo is equal to the radial phase velocity vpr, and the slope of the energy line across the neighboring striations is equal to the radial group velocity vgr of the wave packet; the horizontal distance between two neighboring striations is equal to the characteristic wave period τ. Then, one can inversely calculate all the properties of the gravity wave responsible for the appearance of the QP echoes. We found that the possibility of some QP echoes being generated by the gravity waves originated from lower altitudes cannot be ruled out.

  10. Selective solid-phase extraction of trace cadmium(II) with an ionic imprinted polymer prepared from a dual-ligand monomer

    A novel dual-ligand reagent (2Z)-N,N'-bis(2-aminoethylic)but-2-enediamide, was synthesized and applied to prepare metal ion-imprinted polymers (IIPs) materials by ionic imprinted technique for selective solid-phase extraction (SPE) of trace Cd(II) from aqueous solution. In the first step, Cd(II) formed coordination linkage with the two ethylenediamine groups of the synthetic monomer. Then the complex was copolymerized with pentaerythritol triacrylate (crosslinker) in the presence of 2,2'-azobisisobutyronitrile as initiator. Subsequently, the imprinted Cd(II) was completely removed by leaching the dried and powdered materials particles with 0.5 M HCl. The obtained IIPs particles exhibited excellent selectivity for target ion. The distribution ratio (D) values of Cd(II)-IIPs for Cd(II) were greatly larger than that for Cu(II), Zn(II) and Hg(II). The relative selective factor (α r) values of Cd(II)/Cu(II), Cd(II)/Zn(II) and Cd(II)/Hg(II) were 25.5, 35.3 and 62.1. The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Cd(II) was 32.56 and 6.30 mg g-1, respectively. Moreover, the times of adsorption equilibration and complete desorption were remarkably short. The prepared Cd(II)-IIPs were shown to be promising for solid-phase extraction coupled with inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of trace Cd(II) in real samples. The precision (R.S.D.) and detection limit (3σ) of the method were 2.4% and 0.14 μg L-1, respectively. The column packed with Cd(II)-IIPs was good enough for Cd(II) separation in matrixes containing components with similar chemical behaviour such as Cu(II), Zn(II) and Hg(II)

  11. Trace test

    Leykin, Anton; Sottile, Frank

    2016-01-01

    We give a brief derivation of the trace test to verify completeness of a partial witness set of an irreducible variety in affine or projective space. We then consider the trace test for subvarieties of products of projective spaces working with multihomogeneous witness sets. We show how a dimension reduction based on Bertini's Theorem leads to a practical trace test in this case involving a curve in a small-dimensional affine space.

  12. Ingestion and organ content of trace elements of importance in radiological protection. Reference Asian man, phase-2

    The Second Phase of Reference Asian Man Project is in progress with the collaboration of IAEA under Regional Co-operative Agreement to strengthen the radiation protection infrastructure of the country. In this regard dietary samples are being collected from various ecological areas of Pakistan on market basket method. During this Project year, twenty two (22) diet samples were collected, prepared and stored for Neutron Activation Analysis. The stable radionuclides of our primary interest are Sr, Cs, Th, U, I, Ca and K whereas other essential and toxic elements have secondary importance. (author)

  13. Does a prestellar core always become protostellar? Tracing the evolution of cores from the prestellar to protostellar phase

    Anathpindika, S.; Di Francesco, James

    2013-01-01

    Recently, a subset of starless cores whose thermal Jeans mass is apparently overwhelmed by the mass of the core has been identified, e.g., the core {\\small L183}. In literature, massive cores such as this one are often referred to as "super-Jeans cores". As starless cores are perhaps on the cusp of forming stars, a study of their dynamics will improve our understanding of the transition from the prestellar to the protostellar phase. In the present work we use non-magnetic polytropes belonging...

  14. An investigation of trace and isotope light elements in mineral phases from well RN-17 (Reykjanes Peninsula, SW Iceland)

    The light lithophile (Li, Be and B) and halogen (F, Cl) elements are powerful tracers of fluid transfer due to their mobility during high temperature hydrothermal processes and metamorphic devolatilisation. Moreover, although a great deal of studies have been carried out on these elements in whole rock and minerals of altered rocks from divergent and convergent plate margins, an inventory for mineral phases from the altered Icelandic oceanic crust is still incomplete. In the present paper we report the results of in situ EPMA and SIMS investigations on variously altered magmatic (plagioclase and clinopyroxene) and hydrothermal phases (amphibole and epidote) from selected cuttings drilled at different depths (400 - 3000 m) of the well RN-17, Reykjanes geothermal system (SW Iceland). Our study has benefited from the use of high-magnification SEM investigations; from ICP-MS on Li, P-TIMS determinations of boron isotope composition (δ11B) and ID analyses of B contents on the whole rock. Particularly, SIMS data on epidote have shown that alteration beneath Reykjanes has been more efficient in the shallow and intermediate cuttings, while whole rock data on boron isotope composition have revealed that the alteration has been caused firstly by δ11B-poor fluids and successively by δ11B-rich seawater-hydrothermal fluids.

  15. THE TWO-PHASE FORMATION HISTORY OF SPIRAL GALAXIES TRACED BY THE COSMIC EVOLUTION OF THE BAR FRACTION

    We study the evolution of galactic bars and the link with disk and spheroid formation in a sample of zoom-in cosmological simulations. Our simulation sample focuses on galaxies with present-day stellar masses in the 1010-1011 M☉ range, in field and loose group environments, with a broad variety of mass growth histories. In our models, bars are almost absent from the progenitors of present-day spirals at z > 1.5, and they remain rare and generally too weak to be observable down to z ≈ 1. After this characteristic epoch, the fractions of observable and strong bars rise rapidly, bars being present in 80% of spiral galaxies and easily observable in two thirds of these at z ≤ 0.5. This is quantitatively consistent with the redshift evolution of the observed bar fraction, although the latter is presently known up to z ≈ 0.8 because of band-shifting and resolution effects. Our models hence predict that the decrease in the bar fraction with increasing redshift should continue with a fraction of observable bars not larger than 10%-15% in disk galaxies at z > 1. Our models also predict later bar formation in lower-mass galaxies, in agreement with existing data. We find that the characteristic epoch of bar formation, namely redshift z ≈ 0.8-1 in the studied mass range, corresponds to the epoch at which today's spirals acquire their disk-dominated morphology. At higher redshift, disks tend to be rapidly destroyed by mergers and gravitational instabilities and rarely develop significant bars. We hence suggest that the bar formation epoch corresponds to the transition between an early 'violent' phase of spiral galaxy formation at z ≥ 1 and a late 'secular' phase at z ≤ 0.8. In the secular phase, the presence of bars substantially contributes to the growth of the (pseudo-)bulge, but the bulge mass budget remains statistically dominated by the contribution of mergers, interactions, and disk instabilities at high redshift. Early bars at z > 1 are often short

  16. Solvent-free sample preparation by headspace solid-phase microextraction applied to the tracing of n-butyl nitrite abuse.

    Tytgat, J; Daenens, P

    1996-01-01

    The most common alkyl nitrites encountered in forensic toxicology are iso-butyl, n-butyl and iso-pentyl(amyl) nitrites. All have become popular as an aphrodisiac, especially among the homosexual population. Alkyl nitrites are a volatile and unstable group of compounds, which hydrolyse in aqueous matrices to the alcohol and nitrite ion. Here we describe a fast, clean and sensitive procedure for the detection of hydrolysed n-butyl nitrite in whole human blood using a new, solvent-free sampling technique, the headspace solid-phase micro-extraction (HSPME), combined with GC/FID analysis. Sample preparation was investigated using two different stationary phases (100 microns polydimethylsiloxane and 85 microns polyacrylate), coating a fused silica fibre. The effect of different sampling times at fixed temperatures was also studied. Our results demonstrate that the HSPME/GC/FID procedure allows tracing of n-butyl nitrite abuse and detects hydrolysed n-butyl nitrite, i.e., released n-butanol, in whole blood at the 1 ng/mL level. PMID:8956991

  17. Solvent-assisted dispersive solid-phase extraction: A sample preparation method for trace detection of diazinon in urine and environmental water samples.

    Aladaghlo, Zolfaghar; Fakhari, Alireza; Behbahani, Mohammad

    2016-09-01

    In this research, a sample preparation method termed solvent-assisted dispersive solid-phase extraction (SA-DSPE) was applied. The used sample preparation method was based on the dispersion of the sorbent into the aqueous sample to maximize the interaction surface. In this approach, the dispersion of the sorbent at a very low milligram level was received by inserting a solution of the sorbent and disperser solvent into the aqueous sample. The cloudy solution created from the dispersion of the sorbent in the bulk aqueous sample. After pre-concentration of the diazinon, the cloudy solution was centrifuged and diazinon in the sediment phase dissolved in ethanol and determined by gas chromatography-flame ionization detector. Under the optimized conditions (pH of solution=7.0, Sorbent: benzophenone, 2%, Disperser solvent: ethanol, 500μL, Centrifuge: centrifuged at 4000rpm for 3min), the method detection limit for diazinon was 0.2, 0.3, 0.3 and 0.3μgL(-1) for distilled water, lake water, waste water and urine sample, respectively. Furthermore, the pre-concentration factor was 363.8, 356.1, 360.7 and 353.38 in distilled water, waste water, lake water and urine sample, respectively. SA-DSPE was successfully used for trace monitoring of diazinon in urine, lake and waste water samples. PMID:27495366

  18. Analysis of trace levels of sulfonamide and tetracycline antimicrobials in groundwater and surface water using solid-phase extraction and liquid chromatography/mass spectrometry

    Lindsey, M.E.; Meyer, M.; Thurman, E.M.

    2001-01-01

    A method has been developed for the trace analysis of two classes of antimicrobials consisting of six sulfonamides (SAs) and five tetracyclines (TCs), which commonly are used for veterinary purposes and agricultural feed additives and are suspected to leach into ground and surface water. The method used solid-phase extraction and liquid chromatography/mass spectrometry (LC/MS) with positive ion electrospray. The unique combination of a metal chelation agent (Na2EDTA) with a macroporous copolymer resulted in quantitative recoveries by solid-phase extraction (mean recovery, 98 ?? 12%) at submicrogram-per-liter concentrations. An ammonium formate/formic acid buffer with a methanol/water gradient was used to separate the antimicrobials and to optimize the signal intensity. Mass spectral fragmentation and ionization characteristics were determined for each class of compounds for unequivocal identification. For all SAs, a characteristic m/z 156 ion representing the sulfanilyl fragment was identified. TCs exhibited neutral losses of 17 amu resulting from the loss of ammonia and 35 amu from the subsequent loss of water. Unusual matrix effects were seen only for TCs in this first survey of groundwater and surface water samples from sites around the United States, requiring that TCs be quantitated using the method of standard additions.

  19. Graphene aerogel based monolith for effective solid-phase extraction of trace environmental pollutants from water samples.

    Han, Qiang; Liang, Qionglin; Zhang, Xiaoqiong; Yang, Liu; Ding, Mingyu

    2016-05-20

    Graphene aerogel (GA), a typical kind of three-dimensional (3D) macroscopic assembly, not only provides inherently excellent properties of graphene sheets (GS), but also exhibits interesting characteristics of the 3D macroporous architecture including large and tunable pore volumes, high specific surface areas and fast mass transport kinetics. Thus, it is rational to expect GA to be an efficient adsorbent for solid-phase extraction (SPE). In this paper, a novel GA monolith based solid-phase extraction method was investigated in the application of environment analysis. The GA monolith based SPE cartridge was fabricated directly in the empty cartridge through template-free "sol-cryo" method. Due to the efficient mass transfer, more adsorption sites as well as effective retention for the analytes, the adsorption property of GA for bisphenol A revealed better performance than that of GS. What's more, GA also outperformed in loading and eluting for target analysis. On the basis of the above advantages, the obtained cartridge was applied for the separation of environmental pollutants from water samples. Taking endocrine disrupting chemicals and polychlorinated biphenyls as the polar and weak polar model analytes, optimizing several parameters influencing the recoveries, limits of detection in the range of 0.01-0.11ngmL(-1) and 0.19-1.53ngL(-1) for the two series of compounds were provided by the established methods. The satisfied sensitivity was accessed and recoveries ranging from 76.3 to 112.5% were obtained for all the analytes when the proposed methods were applied in real water samples analysis. The results revealed the potential of GA as an effective sorbent in sample preparation processes. PMID:27095129

  20. A dipole-assisted solid-phase extraction microchip combined with inductively coupled plasma-mass spectrometry for online determination of trace heavy metals in natural water.

    Shih, Tsung-Ting; Hsu, I-Hsiang; Chen, Shun-Niang; Chen, Ping-Hung; Deng, Ming-Jay; Chen, Yu; Lin, Yang-Wei; Sun, Yuh-Chang

    2015-01-21

    We employed a polymeric material, poly(methyl methacrylate) (PMMA), for fabricating a microdevice and then implanted the chlorine (Cl)-containing solid-phase extraction (SPE) functionality into the PMMA chip to develop an innovative on-chip dipole-assisted SPE technique. Instead of the ion-ion interactions utilized in on-chip SPE techniques, the dipole-ion interactions between the highly electronegative C-Cl moieties in the channel interior and the positively charged metal ions were employed to facilitate the on-chip SPE procedures. Furthermore, to avoid labor-intensive manual manipulation, a programmable valve manifold was designed as an interface combining the dipole-assisted SPE microchip and inductively coupled plasma-mass spectrometry (ICP-MS) to achieve the fully automated operation. Under the optimized operation conditions for the established system, the detection limits for each analyte ion were obtained based on three times the standard deviation of seven measurements of the blank eluent solution. The limits ranged from 3.48 to 20.68 ng L(-1), suggesting that this technique appears uniquely suited for determining the levels of heavy metal ions in natural water. Indeed, a series of validation procedures demonstrated that the developed method could be satisfactorily applied to the determination of trace heavy metals in natural water. Remarkably, the developed device was durable enough to be reused more than 160 times without any loss in its analytical performance. To the best of our knowledge, this is the first study reporting on the combination of a dipole-assisted SPE microchip and elemental analysis instrument for the online determination of trace heavy metal ions. PMID:25426495

  1. Rapid ultra-trace analysis of sucralose in multiple-origin aqueous samples by online solid-phase extraction coupled to high-resolution mass spectrometry.

    Batchu, Sudha Rani; Ramirez, Cesar E; Gardinali, Piero R

    2015-05-01

    Because of its widespread consumption and its persistence during wastewater treatment, the artificial sweetener sucralose has gained considerable interest as a proxy to detect wastewater intrusion into usable water resources. The molecular resilience of this compound dictates that coastal and oceanic waters are the final recipient of this compound with unknown effects on ecosystems. Furthermore, no suitable methodologies have been reported for routine, ultra-trace detection of sucralose in seawater as the sensitivity of traditional liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis is limited by a low yield of product ions upon collision-induced dissociation (CID). In this work, we report the development and field test of an alternative analysis tool for sucralose in environmental waters, with enough sensitivity for the proper quantitation and confirmation of this analyte in seawater. The methodology is based on automated online solid-phase extraction (SPE) and high-resolving-power orbitrap MS detection. Operating in full scan (no CID), detection of the unique isotopic pattern (100:96:31 for [M-H](-), [M-H+2](-), and [M-H+4](-), respectively) was used for ultra-trace quantitation and analyte identification. The method offers fast analysis (14 min per run) and low sample consumption (10 mL per sample) with method detection and confirmation limits (MDLs and MCLs) of 1.4 and 5.7 ng/L in seawater, respectively. The methodology involves low operating costs due to virtually no sample preparation steps or consumables. As an application example, samples were collected from 17 oceanic and estuarine sites in Broward County, FL, with varying salinity (6-40 PSU). Samples included the ocean outfall of the Southern Regional Wastewater Treatment Plant (WWTP) that serves Hollywood, FL. Sucralose was detected above MCL in 78% of the samples at concentrations ranging from 8 to 148 ng/L, with the exception of the WWTP ocean outfall (at pipe end, 28 m below the surface

  2. Dithizone modified magnetic nanoparticles for fast and selective solid phase extraction of trace elements in environmental and biological samples prior to their determination by ICP-OES.

    Cheng, Guihong; He, Man; Peng, Hanyong; Hu, Bin

    2012-01-15

    A fast and simple method for analysis of trace amounts of Cr(III), Cu(II), Pb(II) and Zn(II) in environmental and biological samples was developed by combining magnetic solid phase extraction (MSPE) with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection. Dithizone modified silica-coated magnetic Fe(3)O(4) nanoparticles (H(2)Dz-SCMNPs) were prepared and used for MSPE of trace amounts of Cr(III), Cu(II), Pb(II) and Zn(II). The prepared magnetic nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The factors affecting the extraction of the target metal ions such as pH, sample volume, eluent, and interfering ions had been investigated and the adsorption mechanism of the target metals on the self-prepared H(2)Dz-SCMNPs was investigated by FT-IR and X-ray photo electron spectroscopy (XPS). Under the optimized conditions, the detection limits of the developed method for Cr(III), Cu(II), Pb(II) and Zn(II) were 35, 11, 62, and 8ngL(-1), respectively, with the enrichment factor of 100. The relative standard deviations (RSDs, c=10μgL(-1), n=7) were in the range of 1.7-3.1% and the linear range was 0.1-100μgL(-1). The proposed method had been validated by two certified reference materials (GSBZ50009-88 environmental water and GBW07601 human hair), and the determined values were in good agreement with the certified values. The method was also applied for the determination of trace metals in real water and human hair samples with recoveries in the range of 85-110% for the spiked samples. The developed MSPE-ICP-OES method has the advantages of simplicity, rapidity, selectivity, high extraction efficiency and is suitable for the analysis of samples with large volume and complex matrix. PMID:22265534

  3. Trace methane oxidation studied in several Euryarchaeota under diverse conditions

    James J. Moran

    2005-01-01

    Full Text Available We used 13C-labeled methane to document the extent of trace methane oxidation by Archaeoglobus fulgidus, Archaeoglobus lithotrophicus, Archaeoglobus profundus, Methanobacterium thermoautotrophicum, Methanosarcina barkeri and Methanosarcina acetivorans. The results indicate trace methane oxidation during growth varied among different species and among methanogen cultures grown on different substrates. The extent of trace methane oxidation by Mb. thermoautotrophicum (0.05 ± 0.04%, ± 2 standard deviations of the methane produced during growth was less than that by M. barkeri (0.15 ± 0.04%, grown under similar conditions with H2 and CO2. Methanosarcina acetivorans oxidized more methane during growth on trimethylamine (0.36 ± 0.05% than during growth on methanol (0.07 ± 0.03%. This may indicate that, in M. acetivorans, either a methyltransferase related to growth on trimethylamine plays a role in methane oxidation, or that methanol is an intermediate of methane oxidation. Addition of possible electron acceptors (O2, NO3–, SO22–, SO32– or H2 to the headspace did not substantially enhance or diminish methane oxidation in M. acetivorans cultures. Separate growth experiments with FAD and NAD+ showed that inclusion of these electron carriers also did not enhance methane oxidation. Our results suggest trace methane oxidized during methanogenesis cannot be coupled to the reduction of these electron acceptors in pure cultures, and that the mechanism by which methane is oxidized in methanogens is independent of H2 concentration. In contrast to the methanogens, species of the sulfate-reducing genus Archaeoglobus did not significantly oxidize methane during growth (oxidizing 0.003 ± 0.01% of the methane provided to A. fulgidus, 0.002 ± 0.009% to A. lithotrophicus and 0.003 ± 0.02% to A. profundus. Lack of observable methane oxidation in the three Archaeoglobus species examined may indicate that methyl-coenzyme M reductase, which is not present in

  4. Determination of trace iron in the boiler water used in power generation plants by solid-phase spectrophotometry.

    Sarenqiqige; Maeda, Akihiro; Yoshimura, Kazuhisa

    2014-01-01

    A sensitive, simple and low-cost determination method for the total iron concentration in boiler water systems of power generation plants was developed by solid phase spectrometry (SPS) using 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ) as a coloring agent. The reagents and 0.08 cm(3) of a cation exchanger were added to a 50-cm(3) boiler water sample, then mixed for 30 min to adsorb/concentrate the produced Fe(TPTZ)2(2+) colored complex on the solid beads, resulting in a 625 times concentration of the target analyte without any other procedure. The detection limit of 0.1 μg dm(-3) was obtained, and the optimum conditions for the digestion procedure and color developing reaction was investigated and reported. According to the application of this method to real samples, the present SPS method is the best one because of the shorter analysis time, simpler operation and use of very low-cost equipment compared to the conventional methods, such as TPTZ solution spectrophotometric method after a 16 times concentration, ICP-MS and AAS. PMID:25312633

  5. Selective solid-phase extraction of trace cadmium(II) with an ionic imprinted polymer prepared from a dual-ligand monomer

    Zhai Yunhui [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Liu Yongwen [Department of Chemistry, Shanxi Datong University, Datong 037009 (China); Chang Xijun [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)]. E-mail: zhaiyh03@lzu.cn; Chen Senbin [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Huang Xinping [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

    2007-06-12

    A novel dual-ligand reagent (2Z)-N,N'-bis(2-aminoethylic)but-2-enediamide, was synthesized and applied to prepare metal ion-imprinted polymers (IIPs) materials by ionic imprinted technique for selective solid-phase extraction (SPE) of trace Cd(II) from aqueous solution. In the first step, Cd(II) formed coordination linkage with the two ethylenediamine groups of the synthetic monomer. Then the complex was copolymerized with pentaerythritol triacrylate (crosslinker) in the presence of 2,2'-azobisisobutyronitrile as initiator. Subsequently, the imprinted Cd(II) was completely removed by leaching the dried and powdered materials particles with 0.5 M HCl. The obtained IIPs particles exhibited excellent selectivity for target ion. The distribution ratio (D) values of Cd(II)-IIPs for Cd(II) were greatly larger than that for Cu(II), Zn(II) and Hg(II). The relative selective factor ({alpha} {sub r}) values of Cd(II)/Cu(II), Cd(II)/Zn(II) and Cd(II)/Hg(II) were 25.5, 35.3 and 62.1. The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Cd(II) was 32.56 and 6.30 mg g{sup -1}, respectively. Moreover, the times of adsorption equilibration and complete desorption were remarkably short. The prepared Cd(II)-IIPs were shown to be promising for solid-phase extraction coupled with inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of trace Cd(II) in real samples. The precision (R.S.D.) and detection limit (3{sigma}) of the method were 2.4% and 0.14 {mu}g L{sup -1}, respectively. The column packed with Cd(II)-IIPs was good enough for Cd(II) separation in matrixes containing components with similar chemical behaviour such as Cu(II), Zn(II) and Hg(II)

  6. Synthesis, characterization and application of a new chelating resin for solid phase extraction, preconcentration and determination of trace metals in some dairy samples by flame atomic absorption spectrometry.

    Daşbaşı, Teslima; Saçmacı, Şerife; Çankaya, Nevin; Soykan, Cengiz

    2016-11-15

    In this study, a simple and rapid solid phase extraction/preconcentration procedure was developed for determination of Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Pb(II), and Zn(II) trace metals by flame atomic absorption spectrometry (FAAS). A new chelating resin, poly(N-cyclohexylacrylamide-co-divinylbenzene-co-2-acrylamido-2-methyl-1-propanesulfonic acid) (NCA-co-DVB-co-AMPS) (hereafter CDAP) was synthesized and characterized. The influences of the analytical parameters such as pH of the sample solution, type and concentration of eluent, flow rates of the sample and eluent, volume of the sample and eluent, amount of chelating resin, and interference of ions were examined. The limit of detection (LOD) of analytes were found (3s) to be in the range of 0.65-1.90μgL(-1). Preconcentration factor (PF) of 200 and the relative standard deviation (RSD) of ⩽2% were achieved (n=11). The developed method was applied for determination of analytes in some dairy samples and certified reference materials. PMID:27283608

  7. Analysis of trace mercury in water by solid phase extraction using dithizone modified nanometer titanium dioxide and cold vapor atomic absorption spectrometry

    2007-01-01

    A new method for analysis of trace mercury in water samples was developed, based on the combination of preconcentration/separation using dithizone-modified nanometer titanium dioxide (TiO2) as a solid phase extractant and determination by cold vapor atomic adsorption spectrometry (CVAAS). Dithizone was dissolved with alcohol and loaded on the surface of nano-sized TiO2 powders by stirring. The static adsorption behavior of Hg2+ on the dithizone-modified nanoparticles was investigated in detail. It was found that excellent adsorption ratio for Hg2+ could be obtained in the pH range of 7-8 with an oscillation time of 15 min, and a 5 mL of 3.5 mol·L-1 HCl solution could quantitatively elute Hg2+ from nanometer TiO2 powder. Common coexisting ions caused no obvious influence on the determination of mercury. The mechanisms for the adsorption and desorption were discussed. The detection limit (3σ) for Hg2+ was calculated to be 5 ng·L-1. The proposed method was applied to the determination of Hg2+ in a mineral water sample and a Zhujiang River water sample. By the standard addition method, the average recoveries were found to be 94.4%-108.3% with RSD (n = 5) of 2.9%-3.5%.

  8. Flame atomic absorption spectrometric determination of trace amounts of heavy metal ions after solid phase extraction using modified sodium dodecyl sulfate coated on alumina

    A sensitive and selective solid phase extraction procedure for the determination of traces of Cu(II), Zn(II), Pb(II) and Fe(III) has been developed. An alumina-sodium dodecyl sulfate (SDS) coated on with meso-phenyl bis(indolyl) methane (MPBIM) was used for preconcentration and determination of Cu(II), Zn(II), Pb(II) and Fe(III) ions by flame atomic absorption spectrometry. The analyte ions were adsorbed quantitatively on adsorbent due to their complexation with MPBIM. Adsorbed metals were quantitatively eluted using 6 mL of 4 mol L-1 nitric acid. The effects of parameters such as pH, amount of alumina, amount of MBITP, flow rate, type and concentration of eluting agent were examined. The effects of interfering ions on the separation-preconcentration of analytes were also investigated. The relative standard deviation of the method was found to be less than 3.0%. The presented procedure was successfully applied for determination of analytes in real samples

  9. Trace-chitosan-wrapped multi-walled carbon nanotubes as a new sorbent in dispersive micro solid-phase extraction to determine phenolic compounds.

    Cao, Wan; Hu, Shuai-Shuai; Ye, Li-Hong; Cao, Jun; Xu, Jing-Jing; Pang, Xiao-Qing

    2015-04-17

    This report describes the use of trace-chitosan-wrapped multi-walled carbon nanotubes (CS-MWCNTs) as a sorbent material in dispersive micro solid-phase extraction (DMSPE), which was combined with ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry to analyze phenolic compounds in chrysanthemum tea and a chrysanthemum beverage. In this study, for the first time, CS-MWCNTs were used as a sorbent for this microextraction mode. Moreover, the proposed method exhibits the advantages of simplicity, rapidity, small sample amount and ease of operation. Furthermore, all of the important parameters that affect the extraction efficiency, such as the sorbent, pH, extraction time and type of elution solvent, were investigated and optimized in the DMSPE. Under the optimized extraction condition, the limit of detection, which was calculated based on a signal-to-noise ratio of 3, was 0.22-16.19ngmL(-1). Satisfactory recovery values of 89-106% were obtained for the tested samples. The results show that the developed method was successfully applied to determine the content of chlorogenic acid and flavonoids in complex chrysanthemum samples. PMID:25748543

  10. Magnetic solid-phase extraction clean-up combined with solidified floating organic drop microextraction for determination of trace mercury (ii) in tea samples

    Magnetic solid-phase extraction (MSPE) clean-up combined with solidified floating organic drop microextraction (SFODME) has been developed as a new approach for extraction and determination of trace amounts of mercury (II) in tea samples. After purification of the samples by MSPE with the use of Fe/sub 3/O/sub 4/ at the rate SiO/sub 2/ graphene as sorbents, SFODME technique was used to concentrate the target analytes. Various experimental parameters that could affect the extraction efficiencies were investigated. Under optimized experimental conditions a preconcentration factor of 23.0 was obtained using 15.0 mL sample solution. The calibration graph was linear from 0.05 micro g/L to 5.0 micro g/L with a detection limit of 4.0 ng/L. The relative standard deviation for 10 replicate measurements of 0.1 and 1.0 micro g/L of mercury (II) were 4.27% and 3.95%, respectively. The proposed method was applied in the analysis of four tea samples, and the accuracy of the method was assessed through the analysis of certified reference materials and recovery experiments. (author)

  11. Simultaneous speciation and preconcentration of ultra traces of inorganic tellurium and selenium in environmental samples by hollow fiber liquid phase microextraction prior to electrothermal atomic absorption spectroscopy determination

    A simple and effective speciation and preconcentration method based on hollow fiber liquid phase microextraction (HF-LPME) was developed for simultaneous separation of trace inorganic tellurium and selenium in environmental samples prior to electrothermal atomic absorption spectroscopy (ETAAS) determination. The method involves the selective extraction of the Te (IV) and Se (IV) species by HF-LPME with the use of ammonium pyrrolidinecarbodithioate (APDC) as the chelating agent. The complex compounds were extracted into 10 μL of toluene and the solutions were injected into a graphite furnace for the determination of Te (IV) and Se (IV). To determine the total tellurium and selenium in the samples, first Te (VI) and Se (VI) were reduced to Te (IV) and Se (IV), and then the microextraction method was performed. The experimental parameters of HF-LPME were optimized using a central composite design after a 2n-1 fractional factorial experimental design. Under optimum conditions, enrichment factors of up to 520 and 480 were achieved for Te (IV) and Se (IV), respectively. The detection limits were 4 ng L-1 with 3.5% RSD (n = 5, c = 2.0 μg L-1) for Te (IV) and 5 ng L-1 with 3.1% RSD for Se (IV). The applicability of the developed technique was evaluated by application to spiked, environmental water and soil samples.

  12. Studies in the Philippines on ingestion and organ content of trace elements of importance to radiological protection. Reference Asian man project (phase 2)

    The first Coordinated Research Program (CRP) on Reference Asian Man was conducted for a period of six years. This study dealt with the collection of data in four areas namely, anthropometric measurements, organ mass measurements, nutritional and dietary intake, pulmonary and water balance studies. Results of this study participated by eight Asian member states including the Philippines are contained in the IAEA TECDOC-1005. Based on research needs with reference to radiation protection, dietary intake and tissue analysis appears to be important aspects of the RAM. Hence, the first CRM for Phase 2 held in Manila July 1-4, 1996 strengthened the need to continue the project. Protocols on its implementation were discussed during this meeting. The Philippines presented a report that described the sampling and analytical methods that will be applied. This report aim to present the initial samples collected as well as the data generated from these samples. Elements of interest to radiation protection include Sr, Th, U, 1, Cs and trace elements present in food, water and in selected tissues such as liver, lung, kidney, thyroid and bone

  13. Membrane solid phase microextraction with alumina hollow fiber on line coupled with ICP-OES for the determination of trace copper, manganese and nickel in environmental water samples

    A novel alumina hollow fiber was synthesized by sol-gel template method and was characterized by scanning electron microscopy, N2 adsorption technique and X-ray diffraction. With the use of prepared alumina hollow fiber as extraction membrane, a new method of flow injection (FI)-membrane solid phase microextraction (MSPME) on-line coupled to inductively coupled plasma-optical emission spectrometry (ICP-OES) was developed for simultaneous determination of trace metals (Cu, Mn and Ni) in environmental water samples. The adsorption capacities of the alumina hollow fiber for Cu, Mn and Ni were found to be 6.6, 8.7 and 13.3 mg g-1, respectively. With a preconcentration factor of 10, the limits of detection (LODs) for Cu, Mn and Ni were found to be 0.88, 0.61 and 0.38 ng mL-1, respectively, and the relative standard deviations (RSDs) were ranging from 6.2 to 7.9% (n = 7, c = 10 ng mL-1). To validate the accuracy, the proposed method was applied to the analysis of certified reference material GSBZ50009-88 environmental water and the determined values are in good agreement with the certified values. The developed method was also employed for the analysis of Yangtze River water and East Lake water, and the recoveries for the spiked samples were in the range of 87.4-110.2%.

  14. Preparation and evaluation of solid-phase microextraction fiber based on molecularly imprinted polymers for trace analysis of tetracyclines in complicated samples.

    Hu, Xiaogang; Pan, Jialiang; Hu, Yuling; Huo, Yin; Li, Gongke

    2008-04-25

    Molecularly imprinted polymer (MIP) is widely used in many fields because of its characteristics of high selectivity, chemical stability and easy preparation. To enhance the selectivity and applicability of solid-phase microextraction (SPME), a novel MIP-coated SPME fiber was firstly prepared by multiple co-polymerization method with tetracycline as template. It could be coupled directly to high-performance liquid chromatography (HPLC) and used for trace analysis of tetracyclines (TCs) in complicated samples. The characteristics and application of the fibers were investigated. The electron microscope provided a crosslinked and porous surface, and the average thickness of the MIP coating was 19.5 microm. Compared with the non-imprinted polymer (NIP) coated fibers, the special selectivity to tetracycline and structure-similar oxytetracycline, doxycycline, chlortetracycline were discovered with the MIP-coated fibers. The adsorption and desorption of TCs with the MIP-coated fiber could be achieved quickly. A method for the fluorimetric determination of four TCs by the MIP-coated SPME coupled with HPLC was developed. The optimized extraction conditions such as extraction solvent, desorption solvent, and stirring speed were studied. Linear ranges for the four TCs were 5.00-200 microg/L and detection limits were within the range of 1.0-2.3 microg/L. The method was applied to simultaneous multi-residue analysis of four TCs in the spiked chicken feed, chicken muscle, and milk samples with the satisfactory recoveries. PMID:18325526

  15. Characterizing the gas phase ion chemistry of an ion trap mobility spectrometry based explosive trace detector using a tandem mass spectrometer.

    Kozole, Joseph; Tomlinson-Phillips, Jill; Stairs, Jason R; Harper, Jason D; Lukow, Stefan R; Lareau, Richard T; Boudries, Hacene; Lai, Hanh; Brauer, Carolyn S

    2012-09-15

    A commercial-off-the-shelf (COTS) ion trap mobility spectrometry (ITMS) based explosive trace detector (ETD) has been interfaced to a triple quadrupole mass spectrometer (MS/MS) for the purpose of characterizing the gas phase ion chemistry intrinsic to the ITMS instrument. The overall objective of the research is to develop a fundamental understanding of the gas phase ionization processes in the ITMS based ETD to facilitate the advancement of its operational effectiveness as well as guide the development of next generation ETDs. Product ion masses, daughter ion masses, and reduced mobility values measured by the ITMS/MS/MS configuration for a suite of nitro, nitrate, and peroxide containing explosives are reported. Molecular formulas, molecular structures, and ionization pathways for the various product ions are inferred using the mass and mobility data in conjunction with density functional theory. The predominant product ions are identified as follows: [TNT-H](-) for trinitrotoluene (TNT), [RDX+Cl](-) for cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX), [NO(3)](-) for ethylene glycol dinitrate (EGDN), [NG+NO(3)](-) for nitroglycerine (NG), [PETN+NO(3)](-) for pentaerythritol tetranitrate (PETN), [HNO(3)+NO(3)](-) for ammonium nitrate (NH(4)NO(3)), [HMTD-NC(3)H(6)O(3)+H+Cl](-) for hexamethylene triperoxide diamine (HMTD), and [(CH(3))(2)CNH(2)](+) for triacetone triperoxide (TATP). The predominant ionization pathways for the formation of the various product ions are determined to include proton abstraction, ion-molecule attachment, autoionization, first-order and multi-order thermolysis, and nucleophilic substitution. The ion trapping scheme in the reaction region of the ITMS instrument is shown to increase predominant ion intensities relative to the secondary ion intensities when compared to non-ion trap operation. PMID:22967626

  16. Traceds: An Experimental Trace Element Partitioning Database

    Nielsen, R. L.; Ghiorso, M. S.

    2014-12-01

    The goal of this project, which is part of the EARTHCHEM initiative, is to compile the existing experimental trace element partitioning data, and to develop a transparent, accessible resource for the community. The primary goal of experimental trace element partitioning studies is to create a database that can be used to develop models of how trace elements behave in natural geochemical systems. The range of approaches as to how this is accomplished and how the data are reported differs dramatically from one system to another and one investigator to another. This provides serious challenges to the creation of a coherent database - and suggests the need for a standard format for data presentation and reporting. The driving force for this compilation is to provide community access to the complete database for trace element experiments. Our new effort includes all the published analytical results from experimental determinations. In compiling the data, we have set a minimum standard for the data to be included. The threshold criteria include: Experimental conditions (temperature, pressure, device, container, time, etc.) Major element composition of the phases Trace element analyses of the phases Data sources that did not report these minimum components were not included. The rationale for not including such data is that the degree of equilibration is unknown, and more important, no rigorous approach to modeling the behavior of trace elements is possible without a knowledge of the actual concentrations or the temperature and pressure of formation. The data are stored using a schema derived from that of the Library of Experimental Phase Relations (LEPR), modified to account for additional metadata, and restructured to permit multiple analytical entries for various element/technique/standard combinations. Our ultimate goal is to produce a database together with a flexible user interface that will be useful for experimentalists to set up their work and to build

  17. Restricted accessed nanoparticles for direct magnetic solid phase extraction of trace metal ions from human fluids followed by inductively coupled plasma mass spectrometry detection.

    Yan, Ping; He, Man; Chen, Beibei; Hu, Bin

    2015-06-21

    Herein, restricted accessed magnetic nanoparticles were synthesized by self-assembly of a non-ionic surfactant (Tween-20) onto the 4-(2-pyridylazo)resorcinol (PAR) functionalized magnetic nanoparticles (MNPs). A series of analytical techniques were employed for the characterization of the as-prepared restricted accessed Fe3O4@SiO2@PAR, and it was found that the as-prepared restricted accessed Fe3O4@SiO2@PAR nanoparticles have a porous structure with a BET surface area of around 99.4 m(2) g(-1), an average pore size of about 6.14 nm and a pore volume of 0.47 cm(3) g(-1). Besides, the prepared restricted accessed Fe3O4@SiO2@PAR showed good size exclusion properties toward proteins, providing application potential for the direct analysis of biological samples. Based on this, a novel method of restricted accessed magnetic solid phase extraction (MSPE) combined with inductively coupled plasma-mass spectrometry (ICP-MS) was developed for the direct determination of trace metal ions in human fluids. The parameters affecting the extraction of the target metals by MSPE were studied and the optimized conditions were established. Under the optimum conditions, the adsorption capacity of Cr(III), Cd(II), La(III), Nd(III) and Pb(II) on the as-prepared restricted accessed Fe3O4@SiO2@PAR was 62.9, 56.6, 33.7, 36.9 and 43.3 mg g(-1), respectively. With an enrichment factor of 30, the limits of detection for Cr(III), Cd(II), La(III), Nd(III) and Pb(II) were as low as 11.9, 0.8, 0.7, 1.6 and 4.1 ng L(-1), and the relative standard deviations were 7.6, 8.7, 8.4, 8.1 and 5.0 (C(Cr, Pb) = 0.05 μg L(-1), C(Cd, La) = 0.005 μg L(-1), C(Nd) = 0.01 μg L(-1), n = 7), respectively. The developed method was successfully applied for the direct analysis of free metal ions in human urine and serum samples, and has the advantages of good anti-interference ability, high sensitivity and exhibits great application potential in the direct analysis of trace metals in biological fluids. PMID:25943504

  18. Determination of trace zinc in seawater by coupling solid phase extraction and fluorescence detection in the Lab-On-Valve format.

    Grand, Maxime M; Chocholouš, Petr; Růžička, Jarda; Solich, Petr; Measures, Christopher I

    2016-06-01

    By virtue of their compactness, long-term stability, minimal reagent consumption and robustness, miniaturized sequential injection instruments are well suited for automation of assays onboard research ships. However, in order to reach the sensitivity and limit of detection required for open-ocean determinations of trace elements, it is necessary to preconcentrate the analyte prior its derivatization and subsequent detection by fluorescence. In this work, a novel method for the determination of dissolved zinc (Zn) at subnanomolar levels in seawater is described. The proposed method combines, for the first time, automated matrix removal, extraction of the target element, and fluorescence detection within a miniaturized flow manifold, based on the Lab-On-Valve (LOV) concept. The key feature of the microfluidic manipulation of the sample is flow programming, designed to pass sample through a mini-column where the target analyte and other complexable cations are retained, while the seawater matrix is washed out. Next, zinc is eluted and merged with a Zn selective fluorescent probe (FluoZin-3) at the confluence point of the LOV central channel using two high-precision stepper motor driven pumps that are operated in concert. Finally, the thus formed Zn complex is transported to the LOV flow cell for selective fluorescence measurement. This work describes the characterization and optimization of the method including Solid Phase Extraction using the Toyopearl AF-Chelate-650M resin, and detailed assay protocol controlled by a commercially available software and instrument. The proposed method features a LOD of 0.02 nM, high precision (<3% at 0.1 and 2 nM Zn levels), an assay cycle of 13 min and a reagent consumption of 150 μL FluoZin-3 per sample, which makes the method highly suitable for oceanographic shipboard analysis. The accuracy of the method has been validated through the analysis of seawater reference standards and comparison with ICP-MS determinations on

  19. Provenance Traces

    Cheney, James; Ahmed, Amal

    2008-01-01

    Provenance is information about the origin, derivation, ownership, or history of an object. It has recently been studied extensively in scientific databases and other settings due to its importance in helping scientists judge data validity, quality and integrity. However, most models of provenance have been stated as ad hoc definitions motivated by informal concepts such as "comes from", "influences", "produces", or "depends on". These models lack clear formalizations describing in what sense the definitions capture these intuitive concepts. This makes it difficult to compare approaches, evaluate their effectiveness, or argue about their validity. We introduce provenance traces, a general form of provenance for the nested relational calculus (NRC), a core database query language. Provenance traces can be thought of as concrete data structures representing the operational semantics derivation of a computation; they are related to the traces that have been used in self-adjusting computation, but differ in impor...

  20. Eggshell membrane-based solid-phase extraction combined with hydride generation atomic fluorescence spectrometry for trace arsenic(V) in environmental water samples.

    Zhang, Yongjiang; Wang, Weidong; Li, Lu; Huang, Yuming; Cao, Jia

    2010-03-15

    The eggshell membrane (ESM) contains several surface functional groups such as amines, amides and carboxylic groups with potential as SPE adsorbent for the retention of target species of interest. In this paper, the potential use of ESM, a typical biomaterial, as solid-phase extraction (SPE) adsorbent is evaluated for analysis of trace arsenic(V) in environmental water samples in combination with hydride generation atomic fluorescence spectrometry (HG-AFS). In order to obtain the satisfactory recovery of arsenic(V), various parameters including the desorption and enrichment conditions such as pH, the flow rate and the volume of sample solution, the amount of ESM and the content of sodium chloride were systematically optimized and the effects of co-existed ions were also investigated in detail. Under the optimal conditions, arsenic(V) could be easily extracted by the ESM packed cartridge and the breakthrough adsorption capacity was found to be 3.9 microg g(-1). The favorable limit of detection (LOD) for arsenic(V) was found to be 0.001 microg L(-1) with an enrichment factor of 33.3, and the relative standard deviations (R.S.Ds) was 2.1% for 0.6 microg L(-1) arsenic (n=11). The reproducibility among columns was satisfactory (R.S.D. among columns is less than 5%). The proposed method has been successfully applied to analysis of arsenic(V) in aqueous environmental samples, which suggests the ESM can be an excellent SPE adsorbent for arsenic(V) pretreatment and enrichment from real water samples. PMID:20152431

  1. Molecularly imprinted solid phase extraction using stable isotope labeled compounds as template and liquid chromatography-mass spectrometry for trace analysis of bisphenol A in water sample

    We have developed a molecularly imprinted polymer (MIP) using a stable isotope labeled compound as the template molecule and called it the ''isotope molecularly imprinted polymer'' (IMIP). In this study, bisphenol A (BPA) was used as the model compound. None imprinted polymer (NIP), MIP, dummy molecularly imprinted polymer (DMIP) and IMIP were prepared by the suspension polymerization method using without template, BPA, 4-tert-butylphenol (BP) and bisphenol A-d16 (BPA-d16), respectively. The polymers were subjected to molecularly imprinted solid phase extraction (MI-SPE), and the extracted samples were subjected to liquid chromatography-mass spectrometry (LC-MS). Although the leakage of BPA-d16 from the IMIP was observed and that of BPA was not observed. The selectivity factors of MIP and IMIP for BPA were 4.45 and 4.43, respectively. Therefore, IMIP had the same molecular recognition ability as MIP. When MI-SPE with IMIP was used and followed by LC-MS in the analysis of river water sample, the detection limit of BPA was 1 ppt with high sensitivity. Moreover, the average recovery was higher than 99.8% (R.S.D.: 3.7%) by using bisphenol A-13C12 (BPA-13C12) as the surrogate standard. In addition, the IMIP were employed in MI-SPE of BPA in river water sample by LC-MS. The concentration of BPA in the river water sample was determined to be 32 pg ml-1. We confirmed that it was possible to measure trace amounts of a target analyte by MI-SPE using IMIP

  2. Graphene-based solid-phase extraction combined with flame atomic absorption spectrometry for a sensitive determination of trace amounts of lead in environmental water and vegetable samples

    Wang Yukun; Gao Shutao; Zang Xiaohuan [Hebei Key Laboratory of Bioinorganic Chemistry, College of Sciences, Agricultural University of Hebei, Baoding 071001 (China); Li Jingci, E-mail: jingcili63@yahoo.com.cn [Hebei Key Laboratory of Bioinorganic Chemistry, College of Sciences, Agricultural University of Hebei, Baoding 071001 (China); Ma Jingjun, E-mail: majingjun@hebau.edu.cn [Hebei Key Laboratory of Bioinorganic Chemistry, College of Sciences, Agricultural University of Hebei, Baoding 071001 (China)

    2012-02-24

    Highlights: Black-Right-Pointing-Pointer Graphene as a novel sorbent material in a column for solid-phase extraction (SPE). Black-Right-Pointing-Pointer SPE for the determination of lead (Pb) in environment water samples and vegetable samples. Black-Right-Pointing-Pointer The system can be reused for many times. Black-Right-Pointing-Pointer The adsorption capacity of graphene over many other adsorbents. Black-Right-Pointing-Pointer Graphene has great potentials as an excellent sorbent material. - Abstract: Graphene, a novel class of carbon nanostructures, has great promise for use as sorbent materials because of its ultrahigh specific surface area. A new method using a column packed with graphene as sorbent was developed for the preconcentration of trace amounts of lead (Pb) using dithizone as chelating reagent prior to its determination by flame atomic absorption spectrometry. Some effective parameters on the extraction and complex formation were selected and optimized. Under optimum conditions, the calibration graph was linear in the concentration range of 10.0-600.0 {mu}g L{sup -1} with a detection limit of 0.61 {mu}g L{sup -1}. The relative standard deviation for ten replicate measurements of 20.0 and 400.0 {mu}g L{sup -1} of Pb were 3.56 and 3.25%, respectively. Comparative studies showed that graphene is superior to other adsorbents including C18 silica, graphitic carbon, and single- and multi-walled carbon nanotubes for the extraction of Pb. The proposed method was successfully applied in the analysis of environmental water and vegetable samples. Good spiked recoveries over the range of 95.3-100.4% were obtained. This work not only proposes a useful method for sample preconcentration, but also reveals the great potential of graphene as an excellent sorbent material in analytical processes.

  3. Comparison of the selectivity of different sorbent phases for bar adsorptive microextraction--application to trace level analysis of fungicides in real matrices.

    Almeida, C; Nogueira, J M F

    2012-11-23

    Bar adsorptive micro-extraction combined with liquid desorption followed by large volume injection-gas chromatography-mass spectrometry operating in the selected-ion monitoring acquisition mode (BAμE-LD/LVI-GC-MS(SIM)) was developed for the determination of trace levels of ten fungicides (azoxystrobin, difenoconazole, metalaxyl-M, myclobutanil, penconazole, tebuconazole, flusilazole, cyprodinil, procymidone and benalaxyl) in aqueous matrices. By comparing different sorbent coatings (two activated carbons, two styrene-divinylbenzene and one modified pyrrolidone polymers) through BAμE, the latter phase showed much higher selectivity and capacity offering multiple mechanisms of interaction, even against polydimethylsiloxane by stir bar sorptive extraction. Assays performed on 25 mL of water samples spiked at the 0.8 μg/L level, yielded recoveries ranging from 100.0 to 107.8%, under optimized experimental conditions; BAμE(modified pyrrolidone) - equilibrium time: 4h (1000 rpm), pH 5.5; LD - solvent:methanol/acetonitrile (1/1), 15 min with sonification. The analytical performance showed convenient detection limits (4.0-30.0 ng/L) and excellent linear dynamic ranges (0.04-1.60 μg/L) with remarkable correlation coefficients (r(2)>0.9980). Excellent repeatability was also achieved through intraday (RSD<13.7%) and interday (RSD<9.9%) assays. By using the standard addition methodology, the application of the present analytical approach on tap and ground water, as well as, wine samples revealed good sensitivity and absence of matrix effects. The proposed method operating under floating sampling technology proved to be a suitable sorption-based static microextraction alternative to monitor fungicides in real matrices, showing to be easy to implement, reliable, sensitive, requiring low sample volume and the possibility to choose the most selective sorbent coating according to the targets of interest. PMID:23084822

  4. Solid-phase extraction and simultaneous determination of trace amounts of sulphonated and azo sulphonated dyes using microemulsion-modified-zeolite and multivariate calibration.

    Al-Degs, Yahya S; El-Sheikh, Amjad H; Al-Ghouti, Mohammad A; Hemmateenejad, Bahram; Walker, Gavin M

    2008-05-30

    A simple and rapid analytical method for the determination of trace levels of five sulphonated and azo sulphonated reactive dyes: Cibacron Reactive Blue 2 (C-Blue, trisulphonated dye), Cibacron Reactive Red 4 (C-Red, tetrasulphonated azo dye), Cibacron Reactive Yellow 2 (C-Yellow, trisulphonated azo dye), Levafix Brilliant Red E-4BA (L-Red, trisulphonated dye), and Levafix Brilliant Blue E-4BA (L-Blue, disulphonated dye) in water is presented. Initially, the dyes were preconcentrated from 250 ml of water samples with solid-phase extraction using natural zeolite sample previously modified with a microemulsion. The modified zeolite exhibited an excellent extraction for the dyes from solution. The parameters that influence quantitative recovery of reactive dyes like amount of extractant, volume of dye solution, pH, ionic strength, and extraction-elution flow rate were varied and optimized. After elution of the adsorbed dyes, the concentration of dyes was determined spectrophotometrically with the aid of principle component regression (PCR) method without separation of dyes. The results obtained from PCR method were comparable to those obtained from HPLC method confirming the effectiveness of the proposed method. With the aid of SPE by M-zeolite, the concentration of dyes could be reproducibly detected over the range 25-200 ppb for C-Yellow and L-Blue and from 50 to 250 ppb for C-Blue, C-Red, and L-Red. The multivariate detection limits of dyes were found to be 15 ppb for C-Yellow and L-Blue and 25 ppb for C-Blue, C-Red, and L-Red dyes. The proposed chemometric method gave recoveries from 85.4 to 115.3% and R.S.D. from 1.0 to 14.5% for determination of the five dyes without any prior separation for solutes. PMID:18585163

  5. Acute phase and transport protein synthesis in simulated infection in undernourished men using uniformly labelled Spirulina Platensis

    Although it has been known for many years that injury and infection lead to body nitrogen loss, the reason has remained obscure. In this paper, we develop the argument that the processes that are activated during infection demand the provision of specific amino acids which have to be supplied from body protein. In particular, we show that the positive acute phase proteins are very rich in the aromatic amino acids and the exaggerated use of these amino acids (phenylalanine, tryptophan and tyrosine) in acute phase protein synthesis lead to an endogenous ''amino acid imbalance'' which restricts the use of other amino acids for tissue protein synthesis. Minimally invasive protocols, involving the administration of 15N and 13C-labelled amino acids for studying whole body nitrogen turnover, amino acid oxidation and plasma protein synthesis are described. (author). 22 refs, 3 tabs

  6. Evidence for tropospheric wind shear excitation of high-phase-speed gravity waves reaching the mesosphere using the ray-tracing technique

    M. Pramitha; M. Venkat Ratnam; Taori, A.; B. V. Krishna Murthy; D. Pallamraju; S. Vijaya Bhaskar Rao

    2015-01-01

    Sources and propagation characteristics of high-frequency gravity waves observed in the mesosphere using airglow emissions from Gadanki (13.5° N, 79.2° E) and Hyderabad (17.5° N, 78.5° E) are investigated using reverse ray tracing. Wave amplitudes are also traced back, including both radiative and diffusive damping. The ray tracing is performed using background temperature and wind data obtained from the MSISE-90 and HWM-07 models, respectively. For the Gadanki region, the s...

  7. Gas phase acid, ammonia and aerosol ionic and trace element concentrations at Cape Verde during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) 2007 intensive sampling period

    R. Sander; A. A. P. Pszenny; W. C. Keene; Crete, E.; Deegan, B.; Long, M. S.; J. R. Maben; Young, A. H.

    2013-01-01

    We report mixing ratios of soluble reactive trace gases sampled with mist chambers and the chemical composition of bulk aerosol and volatile inorganic bromine (Brg) sampled with filter packs during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) field campaign at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente island in the tropical North Atlantic in May and June 2007. The gas-phase data include HCl, HNO3, HONO, HCOOH, CH3COOH, NH3,...

  8. Efficacy of head space solid-phase microextraction coupled to gas chromatography-mass spectrometry method for determination of the trace extracellular hydrocarbons of cyanobacteria.

    Guan, Wenna; Zhu, Tao; Wang, Yuejie; Zhang, Zhongyi; Jin, Zhao; Wang, Cong; Bai, Fali

    2016-09-01

    Hydrocarbons are widespread in cyanobacteria, and the biochemical synthetic pathways were recently identified. Intracellular fatty alka(e)nes of cyanobacteria have been detected by liquid-liquid extraction (LLE) coupled to gas chromatography-mass spectrometry (GC/MS). However, whether fatty alka(e)nes can be released to cyanobacterial culture media remains to be clarified. This work develops a sensitive method for analyzing the trace level of extracellular hydrocarbons in cyanobacterial culture media by head space solid-phase microextraction (HS-SPME) coupled to GC/MS. Headspace (HS) extraction mode using polydimethylsiloxane fiber to extract for 30min at 50°C was employed as the optimal extraction conditions. Five cyanobacterial fatty alka(e)nes analogs including pentadecene (C15:1), pentadecane (C15:0), heptadecene (C17:1), heptadecane (C17:0), nonadecane (C19:0) were analyzed, and the data obtained from HS-SPME-GC/MS method were quantified using internal standard peak area comparisons. Limits of detection (LOD), limits of quantitation (LOQ), linear dynamic range, precisions (RSD) and recovery for the analysis of extracellular fatty alka(e)nes of cyanobacteria by HS-SPME-GC/MS were evaluated. The LODs limits of detection (S/N = 3) varied from 10 to 21 ng L-1. The correlation coefficients (r) of the calibration curves ranged from 0.9873 to 0.9977 with a linearity from 0.1 to 50 μg L-1. The RSD values were ranging from 7.8 to 14.0% and from 4.0 to 8.8% at 1.0 μg L-1 and 10.0 μg L-1 standard solutions, respectively. Comparative analysis of extracellular fatty alka(e)nes in the culture media of model cyanobacteria Synechocystis sp. PCC 6803 demonstrated that sensitivity of HS-SPME-GC/MS method was significantly higher than LLE method. Finally, we found that heptadecane can be released into the culture media of Synechocystis sp. PCC 6803 at the later growth period. PMID:27428454

  9. Chelating resin immobilizing carboxymethylated polyethyleneimine for selective solid-phase extraction of trace elements: Effect of the molecular weight of polyethyleneimine and its carboxymethylation rate.

    Kagaya, Shigehiro; Kajiwara, Takehiro; Gemmei-Ide, Makoto; Kamichatani, Waka; Inoue, Yoshinori

    2016-01-15

    The effect of the molecular weight of polyethyleneimine (PEI), defined as a compound having two or more ethyleneamine units, and of its carboxymethylation rate (CM/N), represented by the ratio of ion-exchange capacity to the amount of N on the resin, on the selective solid-phase extraction ability of the chelating resin immobilizing carboxymethylated (CM) PEI was investigated. The chelating resins (24 types) were prepared by immobilization of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, PEI300 (MW=ca. 300), and PEI600 (MW=ca. 600) on methacrylate resins, followed by carboxymethylation with various amounts of sodium monochloroacetate. When resins with approximately the same CM/N ratio (0.242-0.271) were used, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, Zn, and alkaline earth elements increased with increasing the molecular weight of PEIs under acidic and weakly acidic conditions; however, the extraction behavior of Mo and V was only slightly affected. This was probably due to the increase in N content of the resin, resulting in an increase in carboxylic acid groups; the difference in the molecular weight of PEIs immobilized on the resin exerts an insignificant influence on the selective extraction ability. The CM/N ratio considerably affected the extraction behavior for various elements. Under acidic and neutral conditions, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, and Zn increased with increasing CM/N values. However, under these conditions, the recovery of alkaline earth elements was considerably low when a resin with low CM/N ratio was used. This is presumably attributed to the different stability constants of the complexes of these elements with aminocarboxylic acids and amines, and to the electrostatic repulsion between the elements and the protonated amino groups in the CM-PEI. The recovery of Mo and V decreased or varied with increasing CM/N values, suggesting that the extraction of these elements occurred mainly

  10. Trace element emissions. Literature review

    Application of fossil fuels by various utilities results in the emission of trace elements to air, water and solid waste streams. Elements present in coal are released as particles or as vapours during coal combustion or gasification. Owing to the increased consumption of coal, especially for power generation, huge quantities of potentially hazardous trace elements are released into the atmosphere every year. It is necessary to evaluate the emissions of each trace element from coal-fired combustion or gasification systems, and their effects on the environment. Present research interests should be aimed at determining the sources, concentrations, and environmental impact of trace elements related with energy generation and relevant control technologies. Two of the emerging advanced coal gasification technologies, such as integrated gasification combined cycle (IGCC) and integrated gasification fuel cell (IGFC) are presently experiencing potential difficulties due to trace element emissions. In order to control the levels of these contaminants within regulatory limits and to ensure the efficient operation of fuel cells, it is necessary to determine the type and quantity of trace elements emitted from coal gasification-based systems as a function of system, operating conditions, and type of coal. The partitioning of the trace elements is influenced by the gasification conditions. In general, the following gasification conditions are expected to influence the distribution of trace elements between various product streams. (a) reducing and oxidizing environments (b) gas phase composition, pressure and temperature. The present report was aimed at finding and identifying gaps existing in the literature on the trace element transformations during gasification. Also included in the report is the modelling of relevant transformation mechanisms of the trace elements during gasification as a function of coal type and process conditions. 7 figs., 6 tabs., 69 refs

  11. Determination of trace Cd, Cu, Fe, Pb and Zn in diesel and gasoline by inductively coupled plasma mass spectrometry after sample clean up with hollow fiber solid phase microextraction system

    This study reports a simple and efficient method for the determination of trace Cd, Cu, Fe, Pb and Zn in diesel and gasoline samples by inductively coupled plasma mass spectrometry after matrix removal and analyte pre-concentration using hollow fiber-solid phase microextraction (HF–SPME). The optimization of HF-SPME procedure was carried out using two-level full factorial and central composite designs. Four factors (variables), that are, sample solution pH, acceptor phase amount, extraction time and eluent concentration were optimized. Under the optimized experimental conditions, the precision was ≤ 3% (C = 10 μg L−1, n = 15), limits of detection and quantification ranged from 0.1 to 0.3 μg L−1 and 0.3–0.9 μg L−1, respectively, and the maximum preconcentration factor was 30. The HF-SPME method was applied for the determination of trace metals in real gasoline and diesel samples. - Highlights: • Hollow fiber solid phase microextraction of metal ions in diesel and gasoline • Use of hollow fiber-supported sol–gel combined with cation exchange resin • Optimization of HF-SPME using multivariate techniques • Determination of Cd, Cu, Fe, Pb and Zn using ICP–MS • Relatively low LOD and LOQ

  12. Co-ordinated research project: ingestion and organ content of trace elements of importance in radiological protection. Reference Asian man project, phase 2

    This First Research Co-ordination Meeting on Ingestion and Organ Content of Trace Elements was held at the Hotel Rembrandt,Quezon City, the Philippines. Information on individual participant's plans for participation in the CRP, and the progress achieved so far on this and related topics is presented in each country's report. The major themes covered include sampling of diets and tissues, analytical techniques used, analytical quality assurance and data reporting of results

  13. Sequential injection/bead injection lab-on-valve schemes for on-line solid phase extraction and preconcentration of ultra-trace levels of heavy metals with determination by ETAAS and ICPMS

    Wang, Jianhua; Hansen, Elo Harald; Miró, Manuel

    2003-01-01

    are focused on the applications of SI-BI-LOV protocols for on-line microcolumn based solid phase extraction of ultra-trace levels of heavy metals, employing the so-called renewable surface separation and preconcentration manipulatory scheme. Two types of sorbents have been employed as packing material......This communication presents an overview of the state-of-the-art of the exploitation of sequential injection (SI)-bead injection (BI)-lab-on-valve (LOV) schemes for automatic on-line sample pre-treatments interfaced with ETAAS and ICPMS detection as conducted in the authors' group. The discussions...

  14. Application of solvent-assisted dispersive solid phase extraction as a new, fast, simple and reliable preconcentration and trace detection of lead and cadmium ions in fruit and water samples.

    Behbahani, Mohammad; Ghareh Hassanlou, Parmoon; Amini, Mostafa M; Omidi, Fariborz; Esrafili, Ali; Farzadkia, Mehdi; Bagheri, Akbar

    2015-11-15

    In this research, a new sample treatment technique termed solvent-assisted dispersive solid phase extraction (SA-DSPE) was developed. The new method was based on the dispersion of the sorbent into the sample to maximize the contact surface. In this approach, the dispersion of the sorbent at a very low milligram level was achieved by injecting a mixture solution of the sorbent and disperser solvent into the aqueous sample. Thereby, a cloudy solution formed. The cloudy solution resulted from the dispersion of the fine particles of the sorbent in the bulk aqueous sample. After extraction, the cloudy solution was centrifuged and the enriched analytes in the sediment phase dissolved in ethanol and determined by flame atomic absorption spectrophotometer. Under the optimized conditions, the detection limit for lead and cadmium ions was 1.2 μg L(-1) and 0.2 μg L(-1), respectively. Furthermore, the preconcentration factor was 299.3 and 137.1 for cadmium and lead ions, respectively. SA-DSPE was successfully applied for trace determination of lead and cadmium in fruit (Citrus limetta, Kiwi and pomegranate) and water samples. Finally, the introduced sample preparation method can be used as a simple, rapid, reliable, selective and sensitive method for flame atomic absorption spectrophotometric determination of trace levels of lead and cadmium ions in fruit and water samples. PMID:25977001

  15. Solid phase extraction and trace monitoring of cadmium ions in environmental water and food samples based on modified magnetic nanoporous silica

    Omidi, Fariborz; Behbahani, Mohammad; Kalate Bojdi, Majid; Shahtaheri, Seyed Jamaleddin

    2015-12-01

    A new method has been developed for trace separation/preconcentration of cadmium ions using pyridine-functionalized magnetic nanoporous silica material (called Py-Fe3O4@MCM-41) as a new magnetic sorbent and their determination by flame atomic absorption spectrometry (FAAS). The Py-Fe3O4@MCM-41 sorbent was characterized by thermogravimetric analysis, differential thermal analysis, transmission electron microscopy, Fourier transform infrared spectrometry and X-ray diffraction. The modified Fe3O4@MCM-41 can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, amount of functionalized Fe3O4@MCM-41, extraction time, type and quantity of eluent, desorption time, and interfering ions on the extraction efficiency were evaluated and optimized. Under the optimized conditions, the detection limit and relative standard deviation was 0.04 μg L-1 and 2.9%, respectively and the maximum adsorption capacity of the synthesized sorbent for cadmium ions was 154 mg g-1. The proposed method has been applied to the determination of Cd ions at trace levels in real samples such as, rice, onion, carrot, lettuce, parsley, basil, tap water, river water and seawater with satisfactory results.

  16. Preparation and characterization of magnetic nanocomposite of Schiff base/silica/magnetite as a preconcentration phase for the trace determination of heavy metal ions in water, food and biological samples using atomic absorption spectrometry.

    Bagheri, Hasan; Afkhami, Abbas; Saber-Tehrani, Mohammad; Khoshsafar, Hosein

    2012-08-15

    A versatile and robust solid phase with both magnetic property and a very high adsorption capacity is presented on the basis of modification of iron oxide-silica magnetic particles with a newly synthesized Schiff base (Fe(3)O(4)/SiO(2)/L). The structure of the resulting product was confirmed by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) spectrometry and transmission electron microscopy (TEM). We developed an efficient and cost-effective method for the preconcentration of trace amounts of Pb(II), Cd(II) and Cu(II) in environmental and biological samples using this novel magnetic solid phase. Prepared magnetic solid phase is an ideal support because it has a large surface area, good selectivity and can be easily retrieved from large volumes of aqueous solutions. The possible parameters affecting the enrichment were optimized. Under the optimal conditions, the method detection limit was 0.14, 0.19 and 0.12 μg L(-1) for Pb(II), Cd(II) and Cu(II) ions, respectively. The established method has been successfully applied to analyze real samples, and satisfactory results were obtained. All these indicated that this magnetic phase had a great potential in environmental and biological fields. PMID:22841051

  17. Epidemic contact tracing via communication traces.

    Katayoun Farrahi

    Full Text Available Traditional contact tracing relies on knowledge of the interpersonal network of physical interactions, where contagious outbreaks propagate. However, due to privacy constraints and noisy data assimilation, this network is generally difficult to reconstruct accurately. Communication traces obtained by mobile phones are known to be good proxies for the physical interaction network, and they may provide a valuable tool for contact tracing. Motivated by this assumption, we propose a model for contact tracing, where an infection is spreading in the physical interpersonal network, which can never be fully recovered; and contact tracing is occurring in a communication network which acts as a proxy for the first. We apply this dual model to a dataset covering 72 students over a 9 month period, for which both the physical interactions as well as the mobile communication traces are known. Our results suggest that a wide range of contact tracing strategies may significantly reduce the final size of the epidemic, by mainly affecting its peak of incidence. However, we find that for low overlap between the face-to-face and communication interaction network, contact tracing is only efficient at the beginning of the outbreak, due to rapidly increasing costs as the epidemic evolves. Overall, contact tracing via mobile phone communication traces may be a viable option to arrest contagious outbreaks.

  18. Epidemic contact tracing via communication traces.

    Farrahi, Katayoun; Emonet, Rémi; Cebrian, Manuel

    2014-01-01

    Traditional contact tracing relies on knowledge of the interpersonal network of physical interactions, where contagious outbreaks propagate. However, due to privacy constraints and noisy data assimilation, this network is generally difficult to reconstruct accurately. Communication traces obtained by mobile phones are known to be good proxies for the physical interaction network, and they may provide a valuable tool for contact tracing. Motivated by this assumption, we propose a model for contact tracing, where an infection is spreading in the physical interpersonal network, which can never be fully recovered; and contact tracing is occurring in a communication network which acts as a proxy for the first. We apply this dual model to a dataset covering 72 students over a 9 month period, for which both the physical interactions as well as the mobile communication traces are known. Our results suggest that a wide range of contact tracing strategies may significantly reduce the final size of the epidemic, by mainly affecting its peak of incidence. However, we find that for low overlap between the face-to-face and communication interaction network, contact tracing is only efficient at the beginning of the outbreak, due to rapidly increasing costs as the epidemic evolves. Overall, contact tracing via mobile phone communication traces may be a viable option to arrest contagious outbreaks. PMID:24787614

  19. Study on solid phase extraction and flame atomic absorption spectrometry for the determination of some trace metals using a chromosorb 105 column and metal-1-(2-pyridylazo)-2-napthol chelates

    Complete text of publication follows. The aquatic environmental pollution by heavy metals has become a considerable problem for public and scientific concern due to their toxicity to human health. Therefore, determinations of toxic heavy metals, such as Fe(III), Zn(II), Pb(II) and Cu(II) have special importance in environmental samples. Many regulations including standard and reference methods for the determination of heavy metals have been presented. Flame atomic absorption spectrometry (FAAS) is widely used in the determination of heavy metals due to the simplicity of operation and low instrumental and operational cost. However, direct determination of ultra trace heavy metals presented in environmental samples is difficult because their amounts are mostly lower than the detection limit of instruments, and in addition to this nonsuitable matrix problems may occur. These limitations can be overcome by applying a clean up and/or preconcentration step prior to the determination step. Solid phase extraction(SPE) is one of the most efficient methods for separation and preconcentration of trace metal ions. The most simple SPE to be used in practice is based on adsorption of heavy metal ions as chelates. Thereby, in the present work, optimization studies on the retention of metal-1-(2-pyridylazo)-2-napthol (PAN) chelates throughout a column filled Chromosorb 105 resin were carried out for determination of trace metals in environmental samples by FAAS. In this work, firstly, all variables involved in the development of the preconcentration using a Chromosorb 105 column including, pH, sample and eluent volumes, sample and eluent flow rates, interfering effects, etc., were optimized to achieve the best analytical performance. The recovery values for the examined analytes higher than 95 % were obtained at pH 9.0. The preconcentration factors were over 75. The RSDs were <5 %.

  20. Compilation and evaluation of gas-phase diffusion coefficients of reactive trace gases in the atmosphere: volume 2. Organic compounds and Knudsen numbers for gas uptake calculations

    M. J. Tang

    2015-02-01

    Full Text Available Diffusion of organic vapours to the surface of aerosol or cloud particles is an important step for the formation and transformation of atmospheric particles. So far, however, a database of gas phase diffusion coefficients for organic compounds of atmospheric interest has not been available. In this work we have compiled and evaluated gas phase diffusivities (pressure-independent diffusion coefficients of organic compounds reported by previous experimental studies, and we compare the measurement data to estimates obtained with Fuller's semi-empirical method. The difference between measured and estimated diffusivities are mostly Kn although their gas phase diffusivities may vary over a wide range. Knudsen numbers of gases with unknown diffusivity can be approximated by a simple function of particle diameter and pressure and can be used to characterize the influence of diffusion on gas uptake by aerosol or cloud particles. We use a kinetic multi-layer model of gas-particle interaction to illustrate the effects of gas phase diffusion on the condensation of organic compounds with different volatilities. The results show that gas-phase diffusion can play a major role in determining the growth of secondary organic aerosol particles by condensation of low-volatility organic vapours.

  1. Trace Chemistry

    Radhakrishnan, Krishnan; Whitefield, Philip

    1999-01-01

    The goals of the trace chemistry group were to identify the processes relevant to aerosol and aerosol precursor formation occurring within aircraft gas turbine engines; that is, within the combustor, turbine, and nozzle. The topics of discussion focused on whether the chemistry of aerosol formation is homogeneous or heterogeneous; what species are important for aerosol and aerosol precursor formation; what modeling/theoretical activities to pursue; what experiments to carry out that both support modeling activities and elucidate fundamental processes; and the role of particulates in aerosol and aerosol precursor formation. The consensus of the group was that attention should be focused on SO2, SO3, and aerosols. Of immediate concern is the measurement of the concentration of the species SO3, SO2, H2SO4 OH, HO2, H2O2, O, NO, NO2, HONO, HNO3, CO, and CO2 and particulates in various engines, both those currently in use and those in development. The recommendation was that concentration measurements should be made at both the combustor exit and the engine exit. At each location the above species were classified into one of four categories of decreasing importance, Priority I through IV, as follows: Combustor exit: Priority I species - SO3:SO2 ratio, SO3, SO2, and particulates; Priority II species: OH and O; Priority III species - NO and NO2; and Priority IV species - CO and CO2. For the Engine exit: Priority I species - SO3:SO2 ratio, SO3, SO2,H2SO4, and particulates; Priority II species: OH,HO2, H2O2, and O; Priority III species - NO, NO2, HONO, and HNO3; and Priority IV species - CO and CO2. Table I summarizes the anticipated concentration range of each of these species. For particulate matter, the quantities of interest are the number density, size distribution, and composition. In order to provide data for validating multidimensional reacting flow models, it would be desirable to make 2-D, time-resolved measurements of the concentrations of the above species and

  2. Modeling Transcient Trace Data

    Mathur, Anup; Abrams, Marc

    1996-01-01

    This paper introduces a novel technique to construct an empirical workload model fitting time-varying (transient) trace data. The trace can be a categorical or numerical time-series. We model the trace as a Piecewise Independent stochastic process. To estimate the parameters for our model we first build a Rate Evolution Graph from the trace data. Piecewise linear regression is then used to construct a joint time-dependent probablity mass function for the trace data. Two methods are propo...

  3. Flow injection on-line solid phase extraction coupled with inductively coupled plasma mass spectrometry for determination of (ultra)trace rare earth elements in environmental materials using maleic acid grafted polytetrafluoroethylene fibers as sorbent.

    Wang, Zhao-Hui; Yan, Xiu-Ping; Wang, Zhi-Peng; Zhang, Zheng-Pu; Liu, Li-Wen

    2006-09-01

    A new sorbent, maleic acid grafted polytetrafluoroethylene fiber (MA-PTFE), was prepared and evaluated for on-line solid-phase extraction coupled with inductively coupled plasma mass spectrometry (ICP-MS) for fast, selective, and sensitive determination of (ultra)trace rare earth elements (REEs) in environmental samples. The REEs in aqueous samples at pH = 3.0 were selectively extracted onto a microcolumn packed with the MA-PTFE fiber, and the adsorbed REEs were subsequently eluted on-line with 0.9 mol l(-1) HNO3 for ICP-MS determination. The new sorbent extraction system allows effective preconcentration and separation of the REEs from the major matrix constituents of alkali and alkali earth elements, particularly their separation from barium that produces considerable isobaric interferences of 134Ba16O1H+, 135Ba16O+, 136Ba16O1H+, and 137Ba16O+ on 151Eu+ and 153Eu+. With the use of a sample loading flow rate of 7.4 ml min(-1) for 120 s preconcentration, enhancement factors of 69-97 and detection limits (3s) of 1-20 pg l(-1) were achieved at a sample throughput of 22 samples h(-1). The precision (RSD) for 16 replicate determinations of 50 ng l(-1) of REEs was 0.5-1.1%. The developed method was successfully applied to the determination of (ultra)trace REEs in sediment, soil, and seawater samples. PMID:16814561

  4. Determination of trace amounts of hexavalent chromium in drinking waters by dispersive microsolid-phase extraction using modified multiwalled carbon nanotubes combined with total reflection X-ray fluorescence spectrometry

    Bahadir, Z.; Bulut, V. N.; Hidalgo, M.; Soylak, M.; Marguí, E.

    2015-05-01

    A methodology based on the combination of dispersive microsolid-phase extraction (DMSPE) with total reflection X-ray fluorescence (TXRF) spectrometry is proposed for the determination of hexavalent chromium in drinking waters. Multiwalled carbon nanotubes (MWCNTs) modified with the anionic exchanger tricaprylmethylammonium chloride (Aliquat 336) were used as solid sorbents. After the sorption process of Cr(VI) on the modified MWCNTs, the aqueous sample was separated by centrifugation and the loaded MWCNTs were suspended using a small volume of an internal standard solution and analyzed directly by a benchtop TXRF spectrometer, without any elution step. Parameters affecting the extraction process (pH and volume of the aqueous sample, amount of MWCNTs, extraction time) and TXRF analysis (volume of internal standard, volume of deposited suspension on the reflector, drying mode, and instrumental parameters) have been carefully evaluated to test the real capability of the developed methodology for the determination of Cr(VI) at trace levels. Using the best analytical conditions, it was found that the minimum Cr(VI) content that can be detected in an aqueous solution was 3 μg L- 1. This value is almost 20 times lower than the maximum hexavalent chromium content permissible in drinking waters, according to the World Health Organization (WHO). Recoveries for spiked tap and mineral water samples were, in most cases, in the range of 101-108% which demonstrates the suitability of the TXRF methodology for monitoring Cr(VI) at trace levels in drinking water samples.

  5. Graphene-based solid-phase extraction combined with flame atomic absorption spectrometry for a sensitive determination of trace amounts of lead in environmental water and vegetable samples.

    Wang, Yukun; Gao, Shutao; Zang, Xiaohuan; Li, Jingci; Ma, Jingjun

    2012-02-24

    Graphene, a novel class of carbon nanostructures, has great promise for use as sorbent materials because of its ultrahigh specific surface area. A new method using a column packed with graphene as sorbent was developed for the preconcentration of trace amounts of lead (Pb) using dithizone as chelating reagent prior to its determination by flame atomic absorption spectrometry. Some effective parameters on the extraction and complex formation were selected and optimized. Under optimum conditions, the calibration graph was linear in the concentration range of 10.0-600.0 μg L(-1) with a detection limit of 0.61 μg L(-1). The relative standard deviation for ten replicate measurements of 20.0 and 400.0 μg L(-1) of Pb were 3.56 and 3.25%, respectively. Comparative studies showed that graphene is superior to other adsorbents including C18 silica, graphitic carbon, and single- and multi-walled carbon nanotubes for the extraction of Pb. The proposed method was successfully applied in the analysis of environmental water and vegetable samples. Good spiked recoveries over the range of 95.3-100.4% were obtained. This work not only proposes a useful method for sample preconcentration, but also reveals the great potential of graphene as an excellent sorbent material in analytical processes. PMID:22284885

  6. A metal-organic framework sustained by a nanosized Ag12 cuboctahedral node for solid-phase extraction of ultra traces of lead(II) ions

    We show that a metal-organic framework (MOF) sustained by a nanosized Ag12 cuboctahedral node can be applied to selectively extract traces of lead(II) ion from environmental water samples. The MOF was characterized by thermogravimetric and differential thermal analysis, scanning electron microscopy, FTIR, and X-ray diffraction. The effects of pH value, flow rates, of type, concentration and volume of the eluent, of break-through volume and potentially interfering ions on the separation and determination of lead were evaluated. Following desorption with EDTA, Pb(II) was quantified by FAAS. The use of the MOF results in excellent analytical figures of merit including an analytical range from 2 to 180 μg L−1 of Pb(II) (R2 > 0.99); a limit of detection of 500 ng L−1; an adsorption capacity of 120 mg g−1; an extraction efficiency of >95 %, and a relative standard deviation of <4 % (for eight separate column experiments). (author)

  7. Gas phase acid, ammonia and aerosol ionic and trace element concentrations at Cape Verde during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) 2007 intensive sampling period

    Sander, R.; Pszenny, A. A. P.; Keene, W. C.; Crete, E.; Deegan, B.; Long, M. S.; Maben, J. R.; Young, A. H.

    2013-12-01

    We report mixing ratios of soluble reactive trace gases sampled with mist chambers and the chemical composition of bulk aerosol and volatile inorganic bromine (Brg) sampled with filter packs during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) field campaign at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente island in the tropical North Atlantic in May and June 2007. The gas-phase data include HCl, HNO3, HONO, HCOOH, CH3COOH, NH3, and volatile reactive chlorine other than HCl (Cl*). Aerosol samples were analyzed by neutron activation (Na, Al, Cl, V, Mn, and Br) and ion chromatography (SO42-, Cl-, Br-, NH4+, Na+, K+, Mg2+, and Ca2+). Content and quality of the data, which are available under doi:10.5281/zenodo.6956, are presented and discussed.

  8. Gas phase acid, ammonia and aerosol ionic and trace element concentrations at Cape Verde during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe 2007 intensive sampling period

    R. Sander

    2013-12-01

    Full Text Available We report mixing ratios of soluble reactive trace gases sampled with mist chambers and the chemical composition of bulk aerosol and volatile inorganic bromine (Brg sampled with filter packs during the Reactive Halogens in the Marine Boundary Layer (RHaMBLe field campaign at the Cape Verde Atmospheric Observatory (CVAO on São Vicente island in the tropical North Atlantic in May and June 2007. The gas-phase data include HCl, HNO3, HONO, HCOOH, CH3COOH, NH3, and volatile reactive chlorine other than HCl (Cl*. Aerosol samples were analyzed by neutron activation (Na, Al, Cl, V, Mn, and Br and ion chromatography (SO42−, Cl−, Br−, NH4+, Na+, K+, Mg2+, and Ca2+. Content and quality of the data, which are available under doi:10.5281/zenodo.6956, are presented and discussed.

  9. Analyses of the bifid shunt and carbohydrate metabolism in Bifidobacterium spp. using **13C-labeled substrates and gas chromatography-mass spectrometry

    Bifidobacteria are Gram-positive, anaerobic bacteria whose presence in the gastrointestinal tract (GIT) is widely considered as a positive influence on human health. This is especially true in the early development of the infant GIT. Analyses of the genome sequence of Bifidobacterium longum sugges...

  10. Assessing microbial utilization of free versus sorbed Alanine by using position-specific 13C labeling and 13C-PLFA analysis

    Herschbach, Jennifer; Apostel, Carolin; Spielvogel, Sandra; Kuzyakov, Yakov; Dippold, Michaela

    2016-04-01

    Microbial utilization is a key transformation process of soil organic matter (SOM). Sorption of low molecular weight organic substances (LMWOS) to soil mineral surfaces blocks or delays microbial uptake and therefore mineralization of LMWOS to CO2, as well as all other biochemical transformations. We used position-specific labeling, a tool of isotope applications novel to soil science, combined with 13C-phospholipid fatty acid (PLFA) analysis, to assess microbial utilization of sorbed and non-sorbed Alanine in soil. Alanine has various functional groups enabling different sorption mechanisms via its positive charge (e.g. to clay minerals by cation exchange), as well as via its negative charge (e.g. to iron oxides by ligand exchange). To assess changes in the transformation pathways caused by sorption, we added uniformly and position-specifically 13C and 14C labeled Alanine to the Ap of a loamy Luvisol in a short-term (10 days) incubation experiment. To allow for sorption of the tracer solution to an aliquot of this soil, microbial activity was minimized in this subsample by sterilizing the soil by γ-radiation. After shaking, the remaining solutions were filtered and the non-sorbed Alanine was removed with Millipore water and then added to non-sterilized soil. For the free Alanine treatment, solutions with Alanine of similar amount and isotopic composition were prepared, added to the soil and incubated as well. The respired CO2 was trapped in NaOH and its 14C-activity was determined at increasing times intervals. Microbial utilization of Alanine's individual C positions was evaluated in distinct microbial groups classified by 13C-PLFA analysis. Sorption to soil minerals delayed respiration to CO2 and reduced initial respiration rate by 80%. Irrespective of sorption, the highest amount was respired from the carboxylic position (C-1), whereas the amino-bound (C-2) and the methylic position (C-3) were preferentially incorporated into PLFA of microorganisms due to the basic microbial metabolism of C3 molecules in glycolysis. Reconstruction of microbial transformation pathways showed that the C-2 position of Alanine was lost as CO2 faster than its C-3 position regardless of whether the molecule was used ana- or catabolically. The highest incorporations of all positions in PLFA were accomplished by Gram negatives. Free Alanine was preferentially used by highly competitive prokaryotes, while sorbed Alanine was preferred by filamentous microorganisms. In detail, the free living osmotrophic Gram negative bacteria utilize more easily accessible dissolved substances. The utilization of sorbed substances are achieved by less mobile microorganisms, e.g. eukaryotic fungi and Actinomycetes, which form biofilms. None of these findings could have been achieved without the position-specific labeling approach, therefore this method will strongly improve our understanding of stabilization processes and soil C fluxes.

  11. Secretion of 13C-labelled oligosaccharides into human milk and infant's urine after an oral [13C]galactose load.

    Obermeier, S; Rudloff, S; Pohlentz, G; Lentze, M J; Kunz, C

    1999-01-01

    Human milk oligosaccharides seem to play an important role in the infant's defense against bacterial and viral infections of the gastrointestinal and the urogenital tract. In this study, we investigated the influence of dietary carbohydrates on the biosynthesis of lactose and oligosaccharides in the human mammary gland and their renal excretion by the human milk-fed infant. For this purpose, a lactating woman was given 27 g galactose (Gal) containing 2 g [13C] Gal (1-13C/99%) immediately after breakfast. In the following 36 h, milk (5-10 ml) was collected before each nursing. Infant's urine was collected over a period of 24 h. 13C-enrichment was measured in total milk, milk fat and protein, in the carbohydrate fraction as well as in urine by isotope ratio mass spectrometry (IRMS). Milk carbohydrates and deproteinized urine samples were fractionated by Sephadex G25 gel filtration and further analyzed by IRMS, high performance thin layer chromatography and and high pH anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). IRMS revealed that in milk a maximal delta 13CPDB was reached within 8 h after Gal intake which then rapidly declined in the following 8 h. The cumulative 13C-elimination over this first peak was 6.9% of the oral 13C-dose. The highest 13C-enrichment was detectable in the carbohydrate fraction, mainly in lactose and neutral oligosaccharides. Compared to the enrichment of human milk, the delta 13CPDB of infant's urine was delayed. In urine, the highest amount of 13C was found in the Sephadex G25 fractions which mainly contained lactose, fucosyl-lactose, lacto-N-tetraose (LNT), fucosyl-LNT and difucosyl-LNT. For further characterization, individual components were separated by HPAEC-PAD and subsequently analyzed by fast atom bombardment mass spectrometry and IRMS. The data show, that orally applied Gal is incorporated in milk, especially in lactose and neutral oligosaccharides. Obviously, some of these components were absorbed by the infant and then excreted with urine. There, oligosaccharides may serve as analogous receptors for bacterial or viral adhesion molecules, and, hence, may prevent urogenital infections in breastfed infants. PMID:10902537

  12. 13C-enrichment at carbons 8 and 2 of uric acid after 13C-labeled folate dose in man

    To evaluate folate-dependent carbon incorporation into the purine ring, we measured 13C-enrichment independently at C2 and C8 of urinary uric acid (the final catabolite of purines) in a healthy male after an independent oral dose of [6RS]-5-[13C]-formyltetrahydrofolate ([6RS]-5-H13CO-H4folate) or 10-H13CO-7,8-dihydrofolate (10-H13CO-H2folate). The C2 position was 13C-enriched more than C8 after [6RS]-5-H13CO-H4folate, and C2 was exclusively enriched after 10-H13CO-H2folate. The enrichment of C2 was greater from [6RS]-5-H13CO-H4folate than 10-H13CO-H2folate using equimolar bioactive doses. Our data suggest that formyl C of [6RS]-10-H13CO-H4folate was not equally utilized by glycinamide ribotide transformylase (enriches C8) and aminoimidazolecarboxamide ribotide (AICAR) transformylase (enriches C2), and the formyl C of 10-H13CO-H2folate was exclusively used by AICAR transformylase. 10-HCO-H2folate may function in vivo as the predominant substrate for AICAR transformylase in humans

  13. Changes in carbon uptake and allocation patterns in Quercus robur seedlings in response to elevated CO2 and water stress: an evaluation with 13C labelling

    A semi-closed (CO2)-C-13 labelling system (1.5% C-13) was used to assess both carbon uptake and allocation within pedunculate oak seedlings (Quercus robur L) grown under ambient (350 vpm) and elevated (700 vpm) atmospheric CO2 concentration ([CO2]) and in either well-watered or droughted conditions. Pulse-chase C-13 labelling data highlighted the direct positive effect of elevated CO2 on photosynthetic carbon acquisition. Consequently, in well-watered conditions, CO2-enriched plants produced 1.52 times more biomass (dry mass at harvest) and 1.33 times more dry root matter (coarse plus fine roots) over the 22-week growing period than plants grown under ambient [CO2]. The root/shoot biomass ratio was decreased both by drought and [CO2], despite lower N concentrations in CO2-enriched plants. However, both long-term and short-term C allocation to fine roots were not altered by CO2, and relative specific allocation (RSA), a parameter expressing sink strength, was hip her in all plant organs under 700 vpm compared to 350 vpm. Results showed that C availability for growth and metabolic processes was greater in fine roots of oaks grown under an elevated CO2 atmosphere irrespective of soil water availability

  14. Carbon sequestration and estimated carbon credit values as measured using 13C labeling and analysis by an optical breath test analyser

    Full text: Recent developments in optical systems for breath testing have provided a robust, low-cost option for undertaking 13C analysis. Although these systems were initially developed for breath testing for Helicobacter pylori, they have an enormous potential as a soil science research tool. The relatively low cost of the equipment at US$ 15000-25000 is within the research budgets of most institutes or universities. The simplicity of the mechanisms and optical nature mean that the equipment requires relatively low maintenance and minimal training. Thus methods were developed to prepare soil and plant materials for analysis using the breath test analyser. Results that compare the conventional mass spectrometry methods with the breath test analyser will be presented. In combination with simple 13C-plant-labeling techniques it is possible to devise methods for estimating carbon sequestration under different agronomic management practices within a short time frame. This allows an assessment of the carbon credit value of a particular agronomic practice, which can in turn be used by policy makers for decision-making purposes. For a global understanding of the effect of agricultural practices on the carbon cycle data is required from a range of cropping systems and agro-ecological zones. The method and the approach described will allow collection of hard data within a reasonable time frame. (author)

  15. Carbon sequestration and estimated carbon credit values as measured using 13C labeling and analysis by an optical breath test analyser

    Recent developments in optical systems for breath testing have provided a robust, low cost option for undertaking 13C analysis. Although these systems were initially developed for breath testing for Helicobacter pylori, they have potential as a research tool in soil science and agronomy. The relatively low cost of the equipment at US$ 15000-25000 is within the research budgets of most institutes or universities. The operational simplicity of the optical system means that relatively low maintenance and minimal training are required. Thus methods were developed to prepare soil and plant materials for 13C isotope-ratio analysis using the breath test analyser, and results were compared with conventional isotope-ratio analysis by mass spectrometry. In combination with simple 13C plant labeling techniques it is possible to devise methods for estimating carbon sequestration under different agronomic management practices within a short time frame. This allows an assessment of the carbon credit value of a particular agronomic practice, which can in turn be used by policy makers for decision-making purposes. For a global understanding of the effect of agricultural practices on the carbon cycle data is required from a range of cropping systems and agro-ecological zones. The method and the approach described will allow collection of data within a reasonable time frame. (author)

  16. Multidimensional solid-state NMR studies of the structure and dynamics of pectic polysaccharides in uniformly 13C-labeled Arabidopsis primary cell walls

    Dick-Perez, Marilu; Wang, Tuo; Salazar, Andre; Zabotina, Olga A.; Hong, Mei

    2012-07-08

    Plant cell wall (CW) polysaccharides are responsible for the mechanical strength and growth of plant cells; however, the high-resolution structure and dynamics of the CW polysaccharides are still poorly understood because of the insoluble nature of these molecules. Here, we use 2D and 3D magic-angle-spinning (MAS) solid-state NMR (SSNMR) to investigate the structural role of pectins in the plant CW. Intact and partially depectinated primary CWs of Arabidopsis thaliana were uniformly labeled with 13C and their NMR spectra were compared. Recent 13C resonance assignment of the major polysaccharides in Arabidopsis thaliana CWs allowed us to determine the effects of depectination on the intermolecular packing and dynamics of the remaining wall polysaccharides. 2D and 3D correlation spectra show the suppression of pectin signals, confirming partial pectin removal by chelating agents and sodium carbonate. Importantly, higher cross peaks are observed in 2D and 3D 13C spectra of the depectinated CW, suggesting higher rigidity and denser packing of the remaining wall polysaccharides compared with the intact CW. 13C spin–lattice relaxation times and 1H rotating-frame spin–lattice relaxation times indicate that the polysaccharides are more rigid on both the nanosecond and microsecond timescales in the depectinated CW. Taken together, these results indicate that pectic polysaccharides are highly dynamic and endow the polysaccharide network of the primary CW with mobility and flexibility, which may be important for pectin functions. This study demonstrates the capability of multidimensional SSNMR to determine the intermolecular interactions and dynamic structures of complex plant materials under near-native conditions. Copyright © 2012 John Wiley & Sons, Ltd.

  17. 1H and 13C NMR assignments for the glycans in glycoproteins by using 2H/13C-labeled glucose as a metabolic precursor

    In order to understand the role of the glycans in glycoproteins in solution, structural information obtained by NMR spectroscopy is obviously required. However, the assignment of the NMR signals from the glycans in larger glycoproteins is still difficult, mainly due to the lack of appropriate methods for the assignment of the resonances originating from the glycans. By using [U-13C6,2H7]glucose as a metabolic precursor, we have successfully prepared a glycoprotein whose glycan is uniformly labeled with 13C and partially with D at the sugar residues. The D to H exchange ratios at the C1-C6 positions of the sugar residues have been proven to provide useful information for the spectral assignments of the glycan in the glycoprotein. This is the first report on the residue-specific assignment of the anomeric resonances originating from a glycan attached to a glycoprotein by using the metabolic incorporation of hydrogen from the medium into a glycan labeled with [U-13C6,2H7]glucose

  18. Carbon sequestration and estimated carbon credit values as measured using 13C labelling and analysis by means of an optical breath test analyser.

    Hood, R C; Khan, M; Haque, A; Khadir, M; Bonetto, J P; Syamsul, R; Mayr, L; Heiling, M

    2004-05-01

    Recent developments in optical systems (isotope-selective non-dispersive infrared spectrometry) for breath testing have provided a robust, low-cost option for undertaking (13)C analysis. Although these systems were initially developed for breath testing for Helicobacter pylori, they have an enormous potential as a soil science research tool. The relatively low cost of the equipment, US$15,000-25,000, is within the research budgets of most institutes or universities. The simplicity of the mechanisms and optical nature mean that the equipment requires relatively low maintenance and minimal training. Thus methods were developed to prepare soil and plant materials for analysis using the breath test analyser. Results that compare conventional mass spectrometric methods with the breath test analyser will be presented. In combination with simple (13)C-plant-labeling techniques it is possible to devise methods for estimating carbon sequestration under different agronomic management practices within a short time frame. This enables assessment of the carbon credit value of a particular agronomic practice, which can in turn be used by policy makers for decision-making purposes. For global understanding of the effect of agricultural practices on the carbon cycle, data are required from a range of cropping systems and agro-ecological zones. The method and the approach described will enable collection of hard data within a reasonable time. PMID:14963630

  19. Processing of 13C-labelled phytoplankton in a fine-grained sandy-shelf sediment (North Sea): relative importance of different macrofauna species

    Kamp, Anja; Witte, Ursula

    2005-01-01

    during the incubation periods. F. fabula, a facultative (surface) deposit- and suspension-feeder, Lanice conchilega (Polychaeta: Terebellidae), a suspension-feeder and the (sur- face) deposit-feeder Echinocardium cordatum (Echinodermata: Spatangidae) were responsible for the majority of macrofaunal...

  20. Preparation of partially 2H/13C-labelled RNA for NMR studies. Stereo-specific deuteration of the H5′′ in nucleotides

    Cromsigt, Jenny; Schleucher, Jürgen; Gustafsson, Tomas; Kihlberg, Jan; Wijmenga, Sybren

    2002-01-01

    An effective in vitro enzymatic synthesis is described for the production of nucleoside triphosphates (NTPs) which are stereo-specifically deuterated on the H5′′ position with high selectivity (>98%), and which can have a variety of different labels (13C, 15N, 2H) in other positions. The NTPs can subsequently be employed in the enzymatic synthesis of RNAs using T7 polymerase from a DNA template. The stereo-specific deuteration of the H5′′ immediately provides the stereo-specific assignment of...

  1. Trace anomaly driven inflation

    Hawking, Stephen William; Reall, H S

    2001-01-01

    This paper investigates Starobinsky's model of inflation driven by the trace anomaly of conformally coupled matter fields. This model does not suffer from the problem of contrived initial conditions that occurs in inflation driven by a scalar field. The universe is nucleated semi-classically by a cosmological instanton that is much larger than the Planck scale provided there are sufficiently many matter fields. There are two cosmological instantons: the four sphere and a new ``double bubble'' solution. This paper considers a universe nucleated by the four sphere. The AdS/CFT correspondence is used to calculate the correlation function for scalar and tensor metric perturbations during the ensuing de Sitter phase. The analytic structure of the scalar and tensor propagators is discussed in detail. Observational constraints on the model are discussed. Quantum loops of matter fields are shown to strongly suppress short scale metric perturbations, which implies that short distance modifications of gravity would pro...

  2. Tracing carbon assimilation in endosymbiotic deep-sea hydrothermal vent Mytilid fatty acids by 13C-fingerprinting

    F. Dehairs

    2010-05-01

    Full Text Available Bathymodiolus azoricus mussels thrive at Mid-Atlantic Ridge hydrothermal vents, where part of their energy requirements are met via an endosymbiotic association with chemolithotrophic and methanotrophic bacteria. In an effort to describe phenotypic characteristics of the two bacterial endosymbionts and to assess their ability to assimilate CO2, CH4 and multi-carbon compounds, we performed experiments in aquaria using 13C-labeled NaHCO3 (in the presence of H2S, CH4 or amino-acids and traced the incorporation of 13C into total and phospholipid fatty acids (tFA and PLFA, respectively. 14:0, 15:0, 16:1(n-7c+t and 18:1(n-7c+t PLFA were labeled in the presence of H13CO3- (+H2S and 13CH4, while the 12:0 compound became labeled only in the presence of H13CO3− (+H2S. In contrast, the 16:1(n-9, 16:1(n-8 and (n-6, 18:1(n-8c and (n-7, 20:1(n-7 and 18:2(n-7 PLFA were only labeled in the presence of 13CH4. Some of these symbiont-specific fatty acids also appeared to be labeled in mussel gill tFA when incubated with 13C-enriched amino acids, and so were mussel-specific fatty acids such as 22:2(n-7,15. Our results provide experimental evidence for the potential of specific fatty acid markers to distinguish between the two endosymbiotic bacteria, shedding new light on C1 and multi-carbon compound metabolic pathways in B. azoricus and its symbionts.

  3. Ray-tracing

    Ray-tracing procedures applicable to hard X-ray optics are presented. The ray-tracing program was applied to a model beam-line which may be installed in an 8 GeV synchrotron radiation facility. (author)

  4. Determination of trace triazine and chloroacetamide herbicides in tile-fed drainage ditch water using solid-phase microextraction coupled with GC-MS

    Solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) was used to analyze two triazine (atrazine and simazine) and three chloroacetamide herbicides (acetochlor, alachlor, and metolachlor) in water samples from a midwest US agricultural drainage ditch for two growing seasons. The effects of salt concentration, sample volume, extraction time, and injection time on extraction efficiency using a 100-μm polydimethylsiloxane-coated fiber were investigated. By optimizing these parameters, ditch water detection limits of 0.5 μg L-1 simazine and 0.25 μg L-1 atrazine, acetochlor, alachlor, and metolachlor were achieved. The optimum salt concentration was found to be 83% NaCl, while sample volume (10 or 20 mL) negligibly affected analyte peak areas. The optimum extraction time was 40 min, and the optimum injection time was 15 min. Results indicated that atrazine levels in the ditch water exceeded the US maximum contaminant level for drinking water 12% of the time, and atrazine was the most frequently detected among studied analytes. - Solid-phase microextraction methods were successfully developed to quantify low levels of herbicides in tile-fed drain water by gas chromatography-mass spectrometry

  5. The Trace of Superusers

    Samson, Kristine; Abasolo, José

    people’s everyday life.However, traces of culture, the routines and every day habits of immigrant culture can both emerge through informal colonization in the every day and be intentionally designed. By juxtaposing immigrant spatial traces in Santiago Centro with the intentionally designed traces of...

  6. Application of Doehlert optimization and factorial designs in developing and validating a solid-phase spectrophotometric determination of trace levels of cadmium

    Using Response Surface Methodology (RSM) and based on sequential experimental Doehlert designs, a Solid-Phase Spectrophotometric determination of cadmium, at μg/l level, with 4-(2-pyridylazo)resorcinol in the presence of potassium iodide, has been established. The method has been characterized and validated by obtaining the performance characteristics. The IUPAC detection limit is 1.5 μg/l and reproducibility (RSD) in the determination of 76.0 μg/l is 3.4%. Robustness was established using two-level saturated fractional factorial designs. Selectivity was studied and trueness was confirmed with house reference materials. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  7. Polymer-supported ionic liquid solid phase extraction for trace inorganic and organic mercury determination in water samples by flow injection-cold vapor atomic absorption spectrometry.

    Escudero, Leticia B; Olsina, Roberto A; Wuilloud, Rodolfo G

    2013-11-15

    A simple and green technique named polymer-supported ionic liquid solid phase extraction (PSIL-SPE) was developed for mercury (Hg) species determination. Inorganic Hg (InHg) species was complexed with chloride ions followed by its introduction into a flow injection on-line system to quantitatively retain the anionic chlorocomplex (HgCl4(2-)) in a column packed with CYPHOS(®) IL 101-impregnated resin. The trapped InHg was then reduced with stannous chloride (SnCl2) and eluted with the same flow of reducing agent followed by cold vapor atomic absorption spectrometry (CV-AAS) detection. Organic mercury species (OrgHg) did not interact with the impregnated resin and were not retained into the column. Total concentration of OrgHg was evaluated by difference between total Hg and InHg concentration. A 95% extraction efficiency was achieved for InHg when the procedure was developed under optimal experimental conditions. The limit of detection obtained for preconcentration of 40 mL of sample was 2.4 ng L(-1) InHg. The relative standard deviation (RSD) was 2.7% (at 1 µg L(-1) InHg and n=10) calculated from the peak height of absorbance signals (Gaussian-shape and reproducible peaks). This work reports the first polymer-supported IL solid phase extraction approach implemented in a flow injection on-line system for determination of Hg species in mineral, tap and river water samples. PMID:24148384

  8. Determination of trace amounts of hexavalent chromium in drinking waters by dispersive microsolid-phase extraction using modified multiwalled carbon nanotubes combined with total reflection X-ray fluorescence spectrometry

    Bahadir, Z. [Department of Chemistry, Giresun University, Giresun (Turkey); Bulut, V.N. [Macka Vocational School, Karadeniz Technical University, Macka, Trabzon (Turkey); Hidalgo, M. [Department of Chemistry, Faculty of Sciences, University of Girona, Girona (Spain); Soylak, M. [Department of Chemistry, Faculty of Sciences, Erciyes University, Kayseri (Turkey); Marguí, E., E-mail: eva.margui@udg.edu [Department of Chemistry, Faculty of Sciences, University of Girona, Girona (Spain)

    2015-05-01

    A methodology based on the combination of dispersive microsolid-phase extraction (DMSPE) with total reflection X-ray fluorescence (TXRF) spectrometry is proposed for the determination of hexavalent chromium in drinking waters. Multiwalled carbon nanotubes (MWCNTs) modified with the anionic exchanger tricaprylmethylammonium chloride (Aliquat 336) were used as solid sorbents. After the sorption process of Cr(VI) on the modified MWCNTs, the aqueous sample was separated by centrifugation and the loaded MWCNTs were suspended using a small volume of an internal standard solution and analyzed directly by a benchtop TXRF spectrometer, without any elution step. Parameters affecting the extraction process (pH and volume of the aqueous sample, amount of MWCNTs, extraction time) and TXRF analysis (volume of internal standard, volume of deposited suspension on the reflector, drying mode, and instrumental parameters) have been carefully evaluated to test the real capability of the developed methodology for the determination of Cr(VI) at trace levels. Using the best analytical conditions, it was found that the minimum Cr(VI) content that can be detected in an aqueous solution was 3 μg L{sup −1}. This value is almost 20 times lower than the maximum hexavalent chromium content permissible in drinking waters, according to the World Health Organization (WHO). Recoveries for spiked tap and mineral water samples were, in most cases, in the range of 101–108% which demonstrates the suitability of the TXRF methodology for monitoring Cr(VI) at trace levels in drinking water samples. - Highlights: • A method using DMSPE and TXRF is proposed for Cr(VI) determination in water. • CNTs modified with a commercial anionic exchanger are used for the DMSPE. • The detection limit for hexavalent chromium is 3 μg L{sup −1}. • Accuracy and precision are suitable for the analysis of tap and mineral waters.

  9. Determination of trace amounts of hexavalent chromium in drinking waters by dispersive microsolid-phase extraction using modified multiwalled carbon nanotubes combined with total reflection X-ray fluorescence spectrometry

    A methodology based on the combination of dispersive microsolid-phase extraction (DMSPE) with total reflection X-ray fluorescence (TXRF) spectrometry is proposed for the determination of hexavalent chromium in drinking waters. Multiwalled carbon nanotubes (MWCNTs) modified with the anionic exchanger tricaprylmethylammonium chloride (Aliquat 336) were used as solid sorbents. After the sorption process of Cr(VI) on the modified MWCNTs, the aqueous sample was separated by centrifugation and the loaded MWCNTs were suspended using a small volume of an internal standard solution and analyzed directly by a benchtop TXRF spectrometer, without any elution step. Parameters affecting the extraction process (pH and volume of the aqueous sample, amount of MWCNTs, extraction time) and TXRF analysis (volume of internal standard, volume of deposited suspension on the reflector, drying mode, and instrumental parameters) have been carefully evaluated to test the real capability of the developed methodology for the determination of Cr(VI) at trace levels. Using the best analytical conditions, it was found that the minimum Cr(VI) content that can be detected in an aqueous solution was 3 μg L−1. This value is almost 20 times lower than the maximum hexavalent chromium content permissible in drinking waters, according to the World Health Organization (WHO). Recoveries for spiked tap and mineral water samples were, in most cases, in the range of 101–108% which demonstrates the suitability of the TXRF methodology for monitoring Cr(VI) at trace levels in drinking water samples. - Highlights: • A method using DMSPE and TXRF is proposed for Cr(VI) determination in water. • CNTs modified with a commercial anionic exchanger are used for the DMSPE. • The detection limit for hexavalent chromium is 3 μg L−1. • Accuracy and precision are suitable for the analysis of tap and mineral waters

  10. Combination of solid phase extraction and dispersive liquid–liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination

    Graphical abstract: Pass the sample through the basic alumina column ⇒ elute retained uranium along with the cations ⇒ convert the uranium to its anionic benzoate complex ⇒ extract its ion pair with malachite green into small volume of chloroform by DLLME ⇒ measure its absorption at 621 nm using fiber optic-linear array detection spectrophotometry. -- Highlights: • By combination of SPE and DDLME a high preconcentration factor of 2500 was obtained. • Development of SPE-DDLME-Spectrophotometric method for det. of trace amounts of uranium. • Ultra trace amount of uranium in water samples was det. by the proposed method. • The detection limit of the proposed method is comparable to the most sensitive method. • The proposed method is a free interference spectrophotometric method for uranium det. -- Abstract: A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid–liquid microextraction. Thus, by passing the sample through the basic alumina column, the uranyl ion and some cations are separated from the sample matrix. The retained uranyl ion along with the cations are eluted with 5 mL of nitric acid (2 mol L−1) and after neutralization of the eluent, the extracted uranyl ion is converted to its anionic benzoate complex and is separated from other cations by extraction of its ion pair with malachite green into small volume of chloroform using dispersive liquid–liquid microextraction. The amount of uranium is then determined by the absorption measurement of the extracted ion pair at 621 nm using flow injection spectrophotometry. Under the optimum conditions, with 500 mL of the sample, a preconcentration factor of 1980, a detection limit of 40 ng L−1, and a relative standard deviation of 4.1% (n = 6) at 400 ng L−1 were obtained. The method was