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Elemental Analyzer (elemental + analyzer)
Selected AbstractsPyrolysis of tetra pack in municipal solid wasteJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2001Chao-Hsiung Wu Abstract The pyrolysis of tetra pack in nitrogen was investigated with a thermogravimetric analysis (TGA) reaction system. The pyrolysis kinetics experiments for the tetra pack and its main components (kraft paper and low-density poly(ethene) (LDPE)) were carried out at heating rates (,) of 5.2, 12.8, 21.8,K,min,1. The results indicated that the one-reaction model and two-reaction model could be used to describe the pyrolysis of LDPE and kraft paper respectively. The total reaction rate of tetra pack can be expressed by the summation of the individual class of LDPE and kraft paper by multiplying the weighting factors. The pyrolysis products experiments were carried out at a constant heating rate of 5.2,K,min,1. The gaseous products were collected at room temperature (298,K) and analyzed by gas chromatography (GC). The residues were collected at some significant pyrolysis reaction temperatures and analyzed by an elemental analyzer (EA) and X-ray powdered diffraction (XRPD). The accumulated masses and the instantaneous concentrations of gaseous products were obtained under the experimental conditions. The major gaseous products included non-hydrocarbons (CO2, CO, and H2O) and hydrocarbons (C1,5). In the XRPD analysis, the results indicated that pure aluminum foil could be obtained from the final residues. The proposed model may be supported by the pyrolysis mechanisms with product distribution. © 2001 Society of Chemical Industry [source] Oxygen isotope analysis of phosphate: improved precision using TC/EA CF-IRMS,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2009D. F. LaPorte Abstract Oxygen isotope values of biogenic apatite have long demonstrated considerable promise for paleothermometry potential because of the abundance of material in the fossil record and greater resistance of apatite to diagenesis compared to carbonate. Unfortunately, this promise has not been fully realized because of relatively poor precision of isotopic measurements, and exceedingly small size of some substrates for analysis. Building on previous work, we demonstrate that it is possible to improve precision of ,18OPO4 measurements using a ,reverse-plumbed' thermal conversion elemental analyzer (TC/EA) coupled to a continuous flow isotope ratio mass spectrometer (CF-IRMS) via a helium stream [Correction made here after initial online publication]. This modification to the flow of helium through the TC/EA, and careful location of the packing of glassy carbon fragments relative to the hot spot in the reactor, leads to narrower, more symmetrically distributed CO elution peaks with diminished tailing. In addition, we describe our apatite purification chemistry that uses nitric acid and cation exchange resin. Purification chemistry is optimized for processing small samples, minimizing isotopic fractionation of PO4,3 and permitting Ca, Sr and Nd to be eluted and purified further for the measurement of ,44Ca and 87Sr/86Sr in modern biogenic apatite and 143Nd/144Nd in fossil apatite. Our methodology yields an external precision of ± 0.15, (1,) for ,18OPO4. The uncertainty is related to the preparation of the Ag3PO4 salt, conversion to CO gas in a reversed-plumbed TC/EA, analysis of oxygen isotopes using a CF-IRMS, and uncertainty in constructing calibration lines that convert raw ,18O data to the VSMOW scale. Matrix matching of samples and standards for the purpose of calibration to the VSMOW scale was determined to be unnecessary. Our method requires only slightly modified equipment that is widely available. This fact, and the demonstrated improvement in precision, should help to make apatite paleothermometry far more accessible to paleoclimate researchers. Copyright © 2009 John Wiley & Sons, Ltd. [source] Compound-specific stable-isotope (,13C) analysis in soil scienceJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2005Bruno Glaser Abstract This review provides current state of the art of compound-specific stable-isotope-ratio mass spectrometry (,13C) and gives an overview on innovative applications in soil science. After a short introduction on the background of stable C isotopes and their ecological significance, different techniques for compound-specific stable-isotope analysis are compared. Analogous to the ,13C analysis in bulk samples, by means of elemental analyzer,isotope-ratio mass spectrometry, physical fractions such as particle-size fractions, soil microbial biomass, and water-soluble organic C can be analyzed. The main focus of this review is, however, to discuss the isotope composition of chemical fractions (so-called molecular markers) indicating plant- (pentoses, long-chain n-alkanes, lignin phenols) and microbial-derived residues (phospholipid fatty acids, hexoses, amino sugars, and short-chain n-alkanes) as well as other interesting soil constituents such as "black carbon" and polycyclic aromatic hydrocarbons. For this purpose, innovative techniques such as pyrolysis,gas chromatography,combustion,isotope-ratio mass spectrometry, gas chromatography,combustion,isotope-ratio mass spectrometry, or liquid chromatography,combustion,isotope-ratio mass spectrometry were compared. These techniques can be used in general for two purposes, (1) to quantify sequestration and turnover of specific organic compounds in the environment and (2) to trace the origin of organic substances. Turnover times of physical (sand < silt < clay) and chemical fractions (lignin < phospholipid fatty acids < amino sugars , sugars) are generally shorter compared to bulk soil and increase in the order given in brackets. Tracing the origin of organic compounds such as polycyclic aromatic hydrocarbons is difficult when more than two sources are involved and isotope difference of different sources is small. Therefore, this application is preferentially used when natural (e.g., C3-to-C4 plant conversion) or artificial (positive or negative) 13C labeling is used. Substanzspezifische Stabilisotopenanalyse (,13C) in der Bodenforschung Dieser Artikel fasst den Stand der Forschung bezüglich der substanzspezifischen Stabilisotopenanalyse (,13C) zusammen. Innovative Anwendungen und ein Ausblick für künftige Forschungsaktivitäten werden anhand von Fallbeispielen gegeben. Zunächst wird die ökologische Bedeutung von stabilen C-Isotopen kurz erläutert. Daran schließt sich ein methodischer Teil an, in welchem die verschiedenen Techniken gegenüber gestellt werden. Analog zu ,13C-Messungen der Feinerde mittels Elementaranalysator-Isotopenverhältnis-Massenspektrometrie können physikalisch isolierte Fraktionen (z.,B. Korngrößenfraktionen, mikrobielle Biomasse, DOC) analysiert werden. Der Schwerpunkt dieses Übersichtsartikels liegt jedoch in der Diskussion der C-Isotopensignatur chemischer Fraktionen (sog. Biomarker), welche Rückschlüsse auf Herkunft und Dynamik pflanzlicher (Pentosen, langkettige n-Alkane, Ligninphenole) und mikrobieller Rückstände (Phospholipidfettsäuren, Hexosen, Aminozucker und kurzkettige n-Alkane) sowie anderer interessanter Substanzen im Boden erlaubt wie z.,B. ,Black Carbon" und polyzyklische aromatische Kohlenwasserstoffe. Zu diesem Zweck kommen innovative Techniken zum Einsatz wie z.,B. Pyrolyse-Gaschromatographie-Isotopenverhältnismassenspektrometrie, Gaschromatographie-Verbrennungs-Isotopenverhältnismassenspektrometrie und Flüssigkeitschromatographie-Oxidations-Isotopenverhältnismassenspektrometrie. Innovative ökologische Anwendungen werden erläutert, welche sich prinzipiell in zwei Kategorien einteilen lassen: (1) Quantifizierung der Sequestrierung und des Umsatzes dieser Verbindungen in der Umwelt; (2) Untersuchung der Herkunft spezifischer organischer Substanzen. Umsatzzeiten physikalischer (Sand < Schluff < Ton) und chemischer Fraktionen (Lignin < Phospholipidfettsäuren < Aminozucker , Zucker) sind generall kleiner als jene der gesamten organischen Substanz in der Feinerde und nehmen in der in Klammern angegebenen Reihenfolge zu. Die Untersuchung der Herkunft organischer Substanzen (z.,B. polyzyklischer aromatischer Kohlenwasserstoffe) ist problematisch, weil die Unterschiede der Isotopensignatur verschiedener Quellen gering sind und meist mehr als zwei Quellen zur Isotopensignatur des untersuchten Biomarkers beitragen. Deswegen sollte die Untersuchung der Herkunft organischer Substanzen auf Tracer-Experimente beschränkt werden, wie z.,B. nach natürlicher (C3-C4-Pflanzenwechsel) bzw. künstlicher (13C-An- oder -Abreicherung) Markierung. [source] Geographic origin of southern Brazilian wines by carbon and oxygen isotope analysesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2010Laurien Adami We present a method that can differentiate between the varieties of grapes and the vintages of wines and show the relationship between the grapes, the wine and the geographic location. The place of origin and its geographic and climatic characteristics were determined by the isotopic ratios, 13C/12C of the ethanol and 18O/16O of the water content of wine (wine water), for southern Brazil wines. The producing subregions of Pinto Bandeira, Vale dos Vinhedos and Nova Pádua showed differences in the temperature, rainfall and humidity conditions used for the production under microvinification conditions of Merlot and Cabernet Sauvignon varieties, in the harvests of 2005 and 2006. An isotope ratio mass spectrometer coupled to an elemental analyzer was used to measure the 13C/12C of ethanol and the 18O/16O of wine water. Regardless of the grape variety used, it was possible to determine the subregion through measurement of the ,18O values in both harvests. The altitudes of the different subregions led to statistical differences and demonstrated an influence mainly on the ,18O values of wine water. The ,18O value of wine water was determined to be more selective for the determination of the cultivation subregions than the ,13C value of the ethanol. The altitude and latitude influenced mainly the , 18O values of wine water and the ethanol. The climatic influences are more noteworthy in distinguishing the year of the harvest than the cultivation subregion. Copyright © 2010 John Wiley & Sons, Ltd. [source] On-line measurements of ,15N in biological fluids by a modified continuous-flow elemental analyzer with an isotope-ratio mass spectrometerRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2008Xu Wang A modified continuous-flow elemental analyzer coupled to an isotope-ratio mass spectrometer (modified EA-IRMS) was tested for on-line ,15N measurement on urea solution and biological fluids (e.g. urine). The elemental analyzer configuration was adapted by adding a U-shaped cold trap and an X-pattern four-way valve for on-line trapping/venting of water from the liquid samples. Results indicate that the ,15N ratios show little variation (standard deviation (SD),=,0.05,) with a sample size above the equivalent N yield of 0.2,mg urea (0.092,mg N) when the mass spectrometer conditions were carefully optimized. By contrast, a significant logarithmic decrease in ,15N with sample size was observed but this can be offset by applying a linearity correction or blank correction when the sample size is between equivalent N yields of 0.05 and 0.2,mg urea. The blank corrected ,15N ratios give an overall precision of ,0.16, whereas the average precision for ,15N corrected using combined linearity and shift correction is 0.05,. The relatively large variation in blank corrected ,15N values may be attributed to the variability of the blank ,15N in the sequence. Therefore, the blank correction should be carefully performed in routine measurements. As a result, the linearity range of a modified EA-IRMS can be extended to a minimum sample size of 0.023,mg N. In addition, the reproducibility of the new system is good, as indicated by the precision (<0.2,) for a set of standards and unknowns. The data show that fluids containing nitrogen can be successfully analyzed in the modified EA-IRMS. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||