Download or read book The Investigation of Negative Ion Chemical Ionization Gas Chromatography Mass Spectrometry as a Routine and Sensitive Detection Method for Residue Analysis of Detagonists and Other Anabolic Agents written by Ita Walsh and published by . This book was released on 1993 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CHEMICAL IONIZATION MASS SPECTROMETRY written by Alex. G. Harrison and published by Springer. This book was released on 1983-05-18 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of the literature on chemical ionization, a method widely used in mass spectrometry, and also extensively applied in structural elucidation and quantitative analytical studies in many branches of chemistry, biochemistry, medicine, and the environmental sciences. Discusses the fundamentals and instrumentation of the technique, reagent ion systems, mass spectra, and other topics. Updated from the first edition of 1982. Annotation copyright by Book News, Inc., Portland, OR
Download or read book Mass Spectrometry for the Analysis of Pesticide Residues and their Metabolites written by Despina Tsipi and published by John Wiley & Sons. This book was released on 2015-04-27 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an overview of the use of mass spectrometry (MS) for the analysis of pesticide residues and their metabolites. Presents state of the-art MS techniques for the identification of pesticides and their transformation products in food and environment Covers important advances in MS techniques including MS instrumentation and chromatographic separations (e.g. UPLC, HILIC, comprehensive GCxGC) and applications Illustrates the main sample preparation techniques (SPE, QuEChERS, microextraction) used in combination with MS for the analysis of pesticides Describes various established and new ionization techniques as well as the main MS platforms, software tools and mass spectral libraries
Download or read book Negative Ion Chemical Ionization GC MS Method Development for Detection of Biogenically Important Polyamines in Human Cadaver Decomposition written by and published by . This book was released on 2018 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The search for the chemical signature of death has focused over the past decade on desorption VOC methods of detection. Our group has been working on a method to detect the less easily detected but biogenically important polyamines that are well known to be part of the decomposition process – putrescine and cadaverine. Putrescine (PUT) and cadaverine (CAD) are known for their malodorous properties and may be important components that human remains detection (HRD) canines detect. To date, there are no published studies that have reported detecting these compounds in any of the forensic research of cadaver decomposition. As polyamines are volatile compounds known to readily absorb on polar surfaces, such as silica, they could be retained in soil for an indeterminate time and be an important factor in the chemical signature that is being detected by the HRD canines. The objective of this project was to determine if small biogenic amines can be detected from soil samples. First the amines were separated from soils as conjugate acids, basified, and extracted into a nonaqueous solvent. Fluorinated amide derivatives of PUT, CAD and other test amines were made and subsequently analyzed by negative ion chemical ionization (NICI) gas chromatography-mass spectrometry (GC-MS). Percent recoveries of the derivatives from sand ranged from 12-69%, and the detection limits were 0.05 ng to 0.20 ng for 1 gram sand samples. Percent recoveries from the same extraction procedures on four mixed soil samples ranged from 0.1 to 32% and experiments to improve recoveries were not successful. Mass spectra of the compounds were also evaluated by electron impact (EI) and positive chemical ionization (PCI), and NICI was found to be the superior method for detection. Difficulties remain in optimizing the extraction process, but the data reveals some interesting fragmentation patterns as well as presenting many questions left to be answered.
Download or read book Studies in Chemical Ionization Mass Spectrometry written by Jean H. Futrell and published by . This book was released on 1975 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: These research efforts have involved studies in chemical ionization mass spectrometry which have led to improved instrumentation, techniques and methodology for trace analysis. Much of the work has emphasized instrumental developments. These have included the development of high pressure ion sources for chemical ionization studies with a high resolution mass spectrometer, the development of super pressure (20 torr) ion sources for exploring maximum sensitivity of chemical ionization mass spectrometry, and, most recently, the development of combined gas chromatography-electron impact-chemical ionization mass spectrometry using a dual source, dual-beam mass spectrometer. This report describes some applications of the latter instrument plus the computer software developed for accumulation of data and data reduction. (Author).
Download or read book Basic Gas Chromatography Mass Spectrometry written by F.W. Karasek and published by . This book was released on 1988-02 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book begins by covering the basic principles of both gas chromatography (GC) and mass spectrometry (MS) to the extent necessary to understand and deal with the data generated in a GC-MS analysis. The focus then turns to the particular requirements created by a direct combination of these two techniques into a single instrumentation system. The data generated and their use are covered in detail. The role of the computer and its specific software receives special attention, especially in the matter of compound identification via mass spectral search techniques. GC-MS-computer instrumentation has reached such a plateau of excellence today that the present commercial systems will not be obsolete for a long time to come. Therefore, a detailed description of these systems is not only informative but is also pertinent to the subject matter of this book. Finally, representative applications and results obtained with GC-MS-computer techniques are presented and chosen in such a way as to permit extrapolation of specific applications to similar problems encountered by the reader. To aid the reader in mastering the subject matter and increase understanding, interpretation problems and suggested readings are included. The format is instructional, informative and application-oriented with material presented in such a way as to be useful to a broad spectrum of people. The book serves as a text in its own right. The software package Gas Chromatography-Mass Spectrometry: A Knowledge Base, by F.A. Settle, Jr. and M.A. Pleva provides rapid access to a wealth of current information in the GC-MS field. Its three diskettes (51/4 inch) allow the user three ways to access: the index mode, the tree mode and a keyword search mode. The package may be purchased separately and is available for the IBM-PC and compatibles. The software provides a valuable supplement to the book.
Download or read book Optimization of the Standard Method of Detection of 4 aminobiphenyl by Negative Ion Chemical Ionization Mass Spectrometry and Investigation of a Method for the Negative Ion Chemical Ionization Detection of N nitrosodimethylamine written by Gary Nelson Lavine and published by . This book was released on 1994 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Anion Detection in the Positive Ion Mode Electrospray Ionization Mass Spectrometry by Use of Cationic Ion Pairing Agents written by Edra Dodbiba and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Anion detection and quantitation has long been of great interest to many scientific areas of research in academic and industrial settings. Their importance extends to areas such as water and environmental analysis, biological system analysis, and also the pharmaceutical and food industries. A variety of sensitive detection methods have been developed for anions. Many of these methods have significant advantages, but also drawbacks. In my dissertation I have described a new method for the detection of anions using electrospray ionization mass spectrometry (ESI-MS) positive ion mode, and cationic ion pairing reagents. Using this method, anions are paired with a plethora of different, di-, tri-, and tetra-cationic ion pairing reagents, thus forming positively charged complexes, which can then be detected in the positive ion mode ESI-MS. The behavior and selectivity of the ion pairing reagents is investigated for the different classes of analytes. During this study, large classes of small organic and inorganic anions were analyzed. In addition, three unique classes of moderate size molecules were investigated. Two of which were biological ones: nucleotides and phospholipids. These are very important molecules, which are responsible for the proper functioning of all biological entities. Nucleotides can exist as monomers or constituents of oligomers, thus they can have more than one negative charge. A total of 28 nucleotide and nucleotide based compounds were paired and analyzed with many different cationic ion pairing reagents. Phospholipids are unique molecules due to their amphipathic character. Phospholipids of different polar groups and different sizes were analyzed in the positive ion mode ESI-MS by using newly synthesized ion pairing reagents. Also, analytical separations of phospholipids were developed using both reverse phase high performance liquid chromatography (HPLC) and hydrophilic interaction liquid chromatography (HILIC) The last class of analytes studied were metal ions. They are already positively charged and therefore they can be detected directly in the positive ion mode ESI-MS, however most of them have a small mass and several oxidation states which usually makes them fall in the low mass to charge region of the mass spectra where the background noise is significant. In this study metals of different oxidation states were complexed with commercially available chelating agents forming negatively charged complexes. Ion pairing agents were added to these compounds forming overall ternary positively charged complexes. Analyses for all types of analytes were performed in both single ion monitoring (SIM) and single reaction monitoring (SRM) modes. Limits of detection (LODs) were easily achieved at the parts per billion (ppb) to parts per trillion (ppt) levels, and significant improvements were noticed in the positive versus negative ion mode ESI-MS. This novel method developed herein shows immense potential for sensitive trace studies of many molecules, high throughput and great simplicity. Lastly a mechanism study by ESI-MS was explored to further understand the low limits of detection achieved by this method.
Download or read book Analysis of Explosives by Negative Ion Chemical Ionization Mass Spectrometry written by J. Yinon and published by . This book was released on 1980 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Negative ion chemical ionization (NCI) mass spectrometry using isobutane as a reagent has been applied to the analysis of explosives. The method is evaluated as complementary to positive ion CI, as both methods can be applied to the same sample. We used a magneticsector-type mass spectrometer without changing the electron multiplier voltage. Under these conditions NCI mass spectra of explosives have been obtained at a sensitivity similar to that of positive ion CI mass spectra.
