Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Language
Year
  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 19 May 2015, Vol.112(20), pp.6325-30
    Description: High-volume hydraulic fracturing (HVHF) has revolutionized the oil and gas industry worldwide but has been accompanied by highly controversial incidents of reported water contamination. For example, groundwater contamination by stray natural gas and spillage of brine and other gas drilling-related fluids is known to occur. However, contamination of shallow potable aquifers by HVHF at depth has never been fully documented. We investigated a case where Marcellus Shale gas wells in Pennsylvania caused inundation of natural gas and foam in initially potable groundwater used by several households. With comprehensive 2D gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS), an unresolved complex mixture of organic compounds was identified in the aquifer. Similar signatures were also observed in flowback from Marcellus Shale gas wells. A compound identified in flowback, 2-n-Butoxyethanol, was also positively identified in one of the foaming drinking water wells at nanogram-per-liter concentrations. The most likely explanation of the incident is that stray natural gas and drilling or HF compounds were driven ∼ 1-3 km along shallow to intermediate depth fractures to the aquifer used as a potable water source. Part of the problem may have been wastewaters from a pit leak reported at the nearest gas well pad-the only nearby pad where wells were hydraulically fractured before the contamination incident. If samples of drilling, pit, and HVHF fluids had been available, GCxGC-TOFMS might have fingerprinted the contamination source. Such evaluations would contribute significantly to better management practices as the shale gas industry expands worldwide.
    Keywords: Marcellus Shale ; High-Volume Hydraulic Fracturing ; Natural Gas ; Shale Gas ; Water Quality ; Water Movements ; Extraction and Processing Industry -- Methods ; Groundwater -- Chemistry ; Natural Gas -- Adverse Effects ; Water Pollutants, Chemical -- Analysis ; Water Supply -- Analysis
    ISSN: 00278424
    E-ISSN: 1091-6490
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Journal of Chromatography A, May 25, 2012, Vol.1239, p.72(6)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.chroma.2012.03.030 Byline: Jessica Westland, Kari Organtini, Frank L. Dorman Keywords: Injector reactivity; GC inlets; GC septa; Reactive compounds; Endrin; 4,4'-DDT; DDT; Merlin Microseal Abstract: a* Average time-to-failure of common silicon-rubber GC septa was studied. a* Merlin Microseal was compared to these materials. a* General inlet inertness as a function of septum degradation was determined. Author Affiliation: The Pennsylvania State University, 107 Whitmore Laboratories, University Park, PA 16802, USA Article History: Received 12 February 2012; Revised 7 March 2012; Accepted 8 March 2012
    Keywords: Chromatography
    ISSN: 0021-9673
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Journal of Chromatography A
    Description: Thermodynamic retention modeling to a thermally modulated comprehensive two-dimensional gas chromatography (GC × GC) system run under constant flow is performed. Significant errors in modeled second dimension retention time (t ) were observed, in line with past work on thermally modulated GC × GC modeling. A comprehensive study of t modeling error for alkane separations across a wide range of heating ramp rates and carrier gas flow rates was performed. Modeling errors were found to be systematic and a function of analyte elution temperature and mobile phase velocity. A model to account for these systematic errors was generated, and associated coefficients were determined which reduced average t retention time error in 144 hydrocarbon separations by an order of magnitude resulting in significant improvement in prediction accuracy. The model was used to correct the separation of 139 Grob mix analyte separations, providing an average t modeling error of 0.030 ± 0.022 s. The model successfully predicted the separation of n-alkanes on a longer second dimension column configuration.
    Keywords: Gc×Gc ; Retention Time Prediction ; Thermodynamic Modeling ; Method Development ; Chemistry
    ISSN: 0021-9673
    E-ISSN: 18733778
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Journal of chromatography, 2012, Vol.1239, pp.72-77
    Description: A comparison of septum degradation data obtained from a variety of standard GC septa, including the Thermogreen™ LB-2, AG3 (Green), Thermolite®, BTO® and the Merlin Microseal™ were evaluated. This study was conducted to determine analytical system lifetime between inlet maintenance based on chromatographic performance of reactive compounds as a function of septum aging through repeated injections. It is widely accepted that gas chromatographic septa degrade relative to the operating temperature of the injector and also based on the physical interaction with the syringe needle. This interaction may cause shedding of particles which then accumulate in the injection port liner, or possibly on the GC column in rare cases. This will likely lead to reactive compound breakdown in the injection port of flash-vaporizing inlets and thus reduce the amount of time that an instrument may be operated between inlet maintenance. Evaluations of the septa were based on the performance of the organochlorine compounds, endrin and 4,4′-DDT. These two compounds act as general indicators for the overall inertness of the GC injector, and their performance may be used to extrapolate to the performance of many other compounds. The average lifetime in terms of the number of injections for the studied septa was determined to range from 151 injections to nearly 2000 injections, depending on the septum. These values were found to be repeatable within the same septa material, or within class. The injection lifetime was found to be statistically different between different septa, however, indicating that not all septa are equivalent in terms of their durability to repeated injections. Additionally, some septa were found to predominately cause degradation of endrin, while others were found to cause reactivity of 4,4′-DDT, indicating that a difference in septa material may cause differences in what types of compounds become reactive in the GC inlet. ; p. 72-77.
    Keywords: Gas Chromatography ; Durability ; Endrin ; Temperature
    ISSN: 0021-9673
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Journal of Chromatography A, 25 May 2012, Vol.1239, pp.72-77
    Description: ► Average time-to-failure of common silicon-rubber GC septa was studied. ► Merlin Microseal was compared to these materials. ► General inlet inertness as a function of septum degradation was determined. A comparison of septum degradation data obtained from a variety of standard GC septa, including the Thermogreen™ LB-2, AG3 (Green), Thermolite , BTO and the Merlin Microseal™ were evaluated. This study was conducted to determine analytical system lifetime between inlet maintenance based on chromatographic performance of reactive compounds as a function of septum aging through repeated injections. It is widely accepted that gas chromatographic septa degrade relative to the operating temperature of the injector and also based on the physical interaction with the syringe needle. This interaction may cause shedding of particles which then accumulate in the injection port liner, or possibly on the GC column in rare cases. This will likely lead to reactive compound breakdown in the injection port of flash-vaporizing inlets and thus reduce the amount of time that an instrument may be operated between inlet maintenance. Evaluations of the septa were based on the performance of the organochlorine compounds, endrin and 4,4′-DDT. These two compounds act as general indicators for the overall inertness of the GC injector, and their performance may be used to extrapolate to the performance of many other compounds. The average lifetime in terms of the number of injections for the studied septa was determined to range from 151 injections to nearly 2000 injections, depending on the septum. These values were found to be repeatable within the same septa material, or within class. The injection lifetime was found to be statistically different between different septa, however, indicating that not all septa are equivalent in terms of their durability to repeated injections. Additionally, some septa were found to predominately cause degradation of endrin, while others were found to cause reactivity of 4,4′-DDT, indicating that a difference in septa material may cause differences in what types of compounds become reactive in the GC inlet.
    Keywords: Injector Reactivity ; Gc Inlets ; Gc Septa ; Reactive Compounds ; Endrin ; 4,4′-Ddt ; Ddt ; Merlin Microseal ; Chemistry
    ISSN: 0021-9673
    E-ISSN: 18733778
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Forensic Science International, 10 September 2013, Vol.231(1-3), pp.e50-e56
    Description: Headspace gas chromatography, coupled to flame ionization detection (GC–FID) analysis of blood alcohol concentration is a routine analysis carried out in forensic laboratories. A common concern with this analysis is the possible co-elution of a variety of other commonly encountered compounds with the target compound ethanol. By use of application specific columns, improved separation of ethanol, as well as the other potential components can be achieved. The presented method includes the evaluation of blood alcohol concentration by both direct gas headspace and SPME utilizing a new combination of GC columns. An investigation of method detection limits (MDLs) was also conducted in order to determine a reporting limit as well as the degree of uncertainty at the common threshold value of 0.08 g/dL. The study showed that under the conditions of this work, static headspace analysis with the use of t-butanol as an internal standard provided the most accurate and precise data with an MDL of 0.002 g/dL for the Rtx – BAC PLUS 1 column and 0.005 g/dL for the Rtx – BAC PLUS 2 column. The study also showed that the SPME analysis using a Carboxen/PDMS (65 μm) fiber with the use of t-butanol provided the lowest overall MDL of 0.0006 g/dL for both Rtx – BAC PLUS 1 and 2 columns without loss of accuracy or precision.
    Keywords: Blood-Alcohol ; Headspace ; Gc–Fid ; Public Health
    ISSN: 0379-0738
    E-ISSN: 1872-6283
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Journal of Chromatography A, July 4, 2014, Vol.1349, p.96(9)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.chroma.2014.04.087 Byline: David Gaddes, Jessica Westland, Frank L. Dorman, Srinivas Tadigadapa Abstract: This work focuses on the development and experimental evaluation of micromachined chromatographic columns for use in a commercial gas chromatography (GC) system. A vespel/graphite ferrule based compression sealing technique is presented using which leak-proof fluidic interconnection between the inlet tubing and the microchannel was achieved. This sealing technique enabled separation at temperatures up to 350[degrees]C on a [mu]GC column. This paper reports the first high-temperature separations in microfabricated chromatographic columns at these temperatures. A 2m microfabricated column using a double Archimedean spiral design with a square cross-section of 100[mu]mx100[mu]m has been developed using silicon microfabrication techniques. The microfabricated column was benchmarked against a 2m 100[mu]m diameter commercial column and the performance between the two columns was evaluated in tests performed under identical conditions. High temperature separations of simulated distillation (ASTM2887) and polycyclic aromatic hydrocarbons (EPA8310) were performed using the [mu]GC column in temperature programmed mode. The demonstrated [mu]GC column along with the high temperature fixture offers one more solution toward potentially realizing a portable [mu]GC device for the detection of semi-volatile environmental pollutants and explosives without the thermal limitations reported to date with [mu]GC columns using epoxy based interconnect technology. Author Affiliation: (a) Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA (b) Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA (c) Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA Article History: Received 14 February 2014; Revised 24 April 2014; Accepted 25 April 2014
    Keywords: Biomedical Engineering ; Epoxy Resins ; Polycyclic Aromatic Hydrocarbons ; Gas Chromatography
    ISSN: 0021-9673
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Analytical chemistry, 04 August 2015, Vol.87(15), pp.7902-8
    Description: The goal of this study was to qualify gas chromatography coupled to atmospheric pressure ionization tandem mass spectrometry (APGC-MS/MS) as a reliable and valid technique for analysis of halogenated dioxins and furans that could be used in place of more traditional gas chromatography coupled to high-resolution mass spectrometry (GC-HRMS) analysis. A direct comparison of the two instrumental techniques was performed. APGC-MS/MS system sensitivity was demonstrated to be on the single femtogram level. The APGC-MS/MS analysis also demonstrated method detection limits (MDLs) in both sediment and fish that were 2-18 times lower than those determined for the GC-HRMS. Inlet conditions were established to prevent issues with sample carry-over, due largely to the enhanced sensitivity of this technique. Additionally, this work utilized direct injection for sample introduction through the split/splittless inlet. Finally, quantification of both sediment and fish certified reference materials were directly compared between the APGC-MS/MS and GC-HRMS. The APGC-MS/MS performed similarly to, if not better than, the GC-HRMS instrument in the analysis of these samples. This data is intended to substantiate APGC-MS/MS as a comparable technique to GC-HRMS for the analysis of dioxins and furans.
    Keywords: Gas Chromatography-Mass Spectrometry ; Tandem Mass Spectrometry ; Dioxins -- Analysis ; Environmental Monitoring -- Methods ; Furans -- Analysis ; Soil Pollutants -- Analysis
    ISSN: 00032700
    E-ISSN: 1520-6882
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Journal of Chromatography A, 04 July 2014, Vol.1349, pp.96-104
    Description: This work focuses on the development and experimental evaluation of micromachined chromatographic columns for use in a commercial gas chromatography (GC) system. A vespel/graphite ferrule based compression sealing technique is presented using which leak-proof fluidic interconnection between the inlet tubing and the microchannel was achieved. This sealing technique enabled separation at temperatures up to 350 °C on a μGC column. This paper reports the first high-temperature separations in microfabricated chromatographic columns at these temperatures. A 2 m microfabricated column using a double Archimedean spiral design with a square cross-section of 100 μm × 100 μm has been developed using silicon microfabrication techniques. The microfabricated column was benchmarked against a 2 m 100 μm diameter commercial column and the performance between the two columns was evaluated in tests performed under identical conditions. High temperature separations of simulated distillation (ASTM2887) and polycyclic aromatic hydrocarbons (EPA8310) were performed using the μGC column in temperature programmed mode. The demonstrated μGC column along with the high temperature fixture offers one more solution toward potentially realizing a portable μGC device for the detection of semi-volatile environmental pollutants and explosives without the thermal limitations reported to date with μGC columns using epoxy based interconnect technology.
    Keywords: Micromachined Column ; Gas Chromatography ; Golay Plots ; High Temperature Separation ; Simulated Distillation ; Polycyclic Aromatic Hydrocarbons ; Chemistry
    ISSN: 0021-9673
    E-ISSN: 18733778
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Journal of Chromatography A, 06 November 2015, Vol.1419, pp.109-115
    Description: An analytical method for identification of emerging contaminants of concern, such as pesticides and organohalogens has been developed and utilized for true discovery-based analysis. In order to achieve the level of sensitivity and selectivity necessary for detecting compounds in complex samples, comprehensive gas chromatography coupled with time-of-flight mass spectrometry (GC × GC–TOFMS) was utilized to analyze wastewater samples obtained from the Pennsylvania State University wastewater treatment facility (WWTF). Determination of emerging contaminants through a process of combining samples which represent “normal background” and comparing this to new samples was developed. Results show the presence of halogenated benzotriazoles in wastewater samples as well as soil samples from Pennsylvania State University agricultural fields. The trace levels of chlorinated benzotriazoles observed in the monitoring wells present on the property indicate likely environmental degradation of the chlorinated benzotriazoles. Preliminary investigation of environmental fate of the substituted benzotriazoles indicates their likely degradation into phenol; an Environmental Protection Agency (USEPA) priority pollutant.
    Keywords: Gc × Gc–Tofms ; Comprehensive Two-Dimensional Gas Chromatography ; Time-of-Flight Mass Spectrometry ; Environmental Forensics ; Chemistry
    ISSN: 0021-9673
    E-ISSN: 18733778
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages