Analysis of Whole/untreated Biological Samples Using Direct Thermal Desorption Combined with Gas Chromatography PDF Download

Author: Lawrence Akoto
Publisher:
ISBN: 9789078675297
Category :
Languages : en
Pages : 161

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 31

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Thermal decomposition of poly dimethyl siloxane compounds, Sylgard{reg_sign} 184 and 186, were examined using thermal desorption coupled gas chromatography-mass spectrometry (TD/GC-MS) and multivariate analysis. This work describes a method of producing multiway data using a stepped thermal desorption. The technique involves sequentially heating a sample of the material of interest with subsequent analysis in a commercial GC/MS system. The decomposition chromatograms were analyzed using multivariate analysis tools including principal component analysis (PCA), factor rotation employing the varimax criterion, and multivariate curve resolution. The results of the analysis show seven components related to offgassing of various fractions of siloxanes that vary as a function of temperature. Thermal desorption coupled with gas chromatography-mass spectrometry (TD/GC-MS) is a powerful analytical technique for analyzing chemical mixtures. It has great potential in numerous analytic areas including materials analysis, sports medicine, in the detection of designer drugs; and biological research for metabolomics. Data analysis is complicated, far from automated and can result in high false positive or false negative rates. We have demonstrated a step-wise TD/GC-MS technique that removes more volatile compounds from a sample before extracting the less volatile compounds. This creates an additional dimension of separation before the GC column, while simultaneously generating three-way data. Sandia's proven multivariate analysis methods, when applied to these data, have several advantages over current commercial options. It also has demonstrated potential for success in finding and enabling identification of trace compounds. Several challenges remain, however, including understanding the sources of noise in the data, outlier detection, improving the data pretreatment and analysis methods, developing a software tool for ease of use by the chemist, and demonstrating our belief that this multivariate analysis will enable superior differentiation capabilities. In addition, noise and system artifacts challenge the analysis of GC-MS data collected on lower cost equipment, ubiquitous in commercial laboratories. This research has the potential to affect many areas of analytical chemistry including materials analysis, medical testing, and environmental surveillance. It could also provide a method to measure adsorption parameters for chemical interactions on various surfaces by measuring desorption as a function of temperature for mixtures. We have presented results of a novel method for examining offgas products of a common PDMS material. Our method involves utilizing a stepped TD/GC-MS data acquisition scheme that may be almost totally automated, coupled with multivariate analysis schemes. This method of data generation and analysis can be applied to a number of materials aging and thermal degradation studies.

Author: Weifang Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 122

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Author:
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ISBN:
Category :
Languages : en
Pages :

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Author:
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Category :
Languages : en
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An instrument was designed and constructed that makes it possible to thermally desorb organic compounds from wet adsorption traps to a gas chromatograph in an efficient and reproducible manner. Based on this device, a method of analyzing organics in water was developed that is rapid, sensitive, and of broader scope than previously published methods. The system was applied to the analysis of compounds with a wide range of volatilities. Temperature and flow parameters were investigated and specific procedures for quantitation were established. Real samples, including tap water and well water, were also analyzed with this system. Depending on the analysis requirements, the thermal desorption instrument can be used with either packed column or high resolution open-tubular column gas chromatography. The construction plans of normal and high-resolution systems are presented along with chromatograms and data produced by each. Finally, an improved thermal desorption instrument is described. Modifications to the basic system, including splitless injection onto a capillary column, automation, dual cryogenic trapping, reduction of scale, and effluent splitting to dual detection are discussed at length as they relate to the improved instrument.

Author: Janusz Pawliszyn
Publisher: Royal Society of Chemistry
ISBN: 1839166800
Category : Science
Languages : en
Pages : 663

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Solid Phase Microextraction (SPME) is a flexible and convenient sampling and sample preparation technique that extracts different kinds of analytes, including both volatile and non-volatile, without the use of a solvent. The technique facilitates fast, simple and automated determination of target analytes in a range of matrices. As it offers a green methodology, it is growing in popularity as an alternative tool in analytical chemistry to traditional methods. This book follows on in spirit from the editors' previous title, Applications of Solid Phase Microextraction and will introduce the reader to breakthrough methodologies and cutting edge applications. Although it assumes a good degree of SPME knowledge, an overview of the fundamentals is given before taking the reader through an update of the field. The reader will learn the basic principles and advantages of different SPME formats including the stir bar extraction techniques, thin film SPME, Bio-SPME, and new trends in different coatings. Applications in complex media, including food analysis, drug residues and bioanalysis are covered. Bringing together leading sample preparation academics from around the world, the editor has put together an informative new book, suitable for analytical chemists and practitioners utilising SPME tools in their research.

Author: Oliver Terzic
Publisher:
ISBN: 9789491407451
Category :
Languages : en
Pages : 221

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"The Organisation for the Prohibition of Chemical Weapons (OPCW) is the international organisation set to oversee the implementation of the Chemical Weapons Convention treaty that prohibits the development, production, acquisition, stockpiling, retention, transfer or use of chemical weapons by States Parties. To this end, the OPCW has established the strict verification procedures relying essentially upon the on-site sampling and analysis. A transportable analytical laboratory was carefully assembled and versed to fit the task. Following more frequent deployment, a major deficiency of the on-site laboratory capacity and the number of weaknesses of the on-site sample preparation approach were revealed. The aim of this PhD thesis was to enhance the capability and efficiency of the OPCW on-site laboratory. The work resulted in a set of novel analytical methods and strategies for the gas chromatography-mass spectrometry instrumental technique that are not restricted to the chemical warfare agent related field, but also convenient for any forensic or environmental field laboratory use."--Samenvatting auteur.

Author: Oliver Terzic
Publisher:
ISBN: 9789491407451
Category :
Languages : en
Pages : 0

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"The Organisation for the Prohibition of Chemical Weapons (OPCW) is the international organisation set to oversee the implementation of the Chemical Weapons Convention treaty that prohibits the development, production, acquisition, stockpiling, retention, transfer or use of chemical weapons by States Parties. To this end, the OPCW has established the strict verification procedures relying essentially upon the on-site sampling and analysis. A transportable analytical laboratory was carefully assembled and versed to fit the task. Following more frequent deployment, a major deficiency of the on-site laboratory capacity and the number of weaknesses of the on-site sample preparation approach were revealed. The aim of this PhD thesis was to enhance the capability and efficiency of the OPCW on-site laboratory. The work resulted in a set of novel analytical methods and strategies for the gas chromatography-mass spectrometry instrumental technique that are not restricted to the chemical warfare agent related field, but also convenient for any forensic or environmental field laboratory use."--Samenvatting auteur.

Author: Sai Hang Ho
Publisher:
ISBN:
Category : Environmental sampling
Languages : en
Pages : 606

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Author: Verner Lagesson
Publisher:
ISBN: 9789170326806
Category :
Languages : en
Pages : 100

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