MS and GC–MS Analytical Methods for On-Line Thermally Induced Evolved Gas Analysis (OLTI-EGA)

Chemical Signalling: Laser on the Fly Reveals a New Male-Specific Pheromone

-En Lipid extracts of sherds of Roman cooking pots from the Temple of Apollo in Hierapolis (southwest Turkey) were analyzed using gas chromatography coupled with mass spectrometry (GCMS). The high relative abundance of saturated fatty acids, especially stearic acid, together with the presence of cholesterol, suggests that animal fats were processed in these pots. The detection of branched and odd chain fatty acids further indicate a possible ruminant source for these lipids. The data show also the presence of plant-derived products, like campesterol and b-sitosterol. The aim of this research is to illustrate how lipid analysis of pottery vessels, together with the information from archaeological context, can contribute to a better understanding of food habits and ritual activities in past ancient societies.

The ability to determine combustion and thermal decomposition (pyrolysis) products at trace concentrations can lead to important information on catalytic pathways, the degradation process itself, and structural (fingerprint) information on the parent molecule(s), among others. Gas chromatography coupled with mass spectrometry (GC/MS) is well suited to separate and identify the volatile molecules and molecular fragments generated by combustion and pyrolysis processes. Whereas, pyrolysis (conducted in an inert atmosphere) is often used as a sample introduction device directly coupled to GC/MS, combustion is generally carried out offline and its products are collected and analyzed with GC/MS, or even pyrolysis‐GC/MS. In the past few years, this powerful technique has been used to examine a variety of sample types for quite diverse applications. This chapter describes the state of the art and the progress of GC/MS for the measurement of combustion and pyrolysis products. An introduction to the technique, including the principles of GC/MS, is first provided, followed by a demonstration of the instrument's capabilities for combustion and pyrolysis research. All reports discussed herein were selected in part to demonstrate the diversity of current combustion and pyrolysis research using GC/MS. The present authors' studies with temperature‐programmed desorption in conjunction with GC/MS to characterize oxygen shuttling on the chars derived from different gaseous environment, are highlighted. Finally, the use of GC/MS in combination with isotope‐labeling techniques to reveal complex reaction pathways and mechanisms is discussed.

Oxidative Decay of DNA

Simultaneous determination of plasmatic phytosterols and cholesterol precursors using gas chromatography–mass spectrometry (GC–MS) with selective ion monitoring (SIM)

Spectroscopic and mass spectrometric analytical techniques were used to characterise two naturally aged Winsor & Newton (W&N) Winsor Green (phthalocyanine green, PG7) artists’ oil colour paint swatches dating to 1993 and 2003. Infrared and Energy Dispersive X-ray (EDX) analysis indicated that the swatches were of closely similar composition, yet the swatch from 2003 was water-sensitive whilst the swatch from 1993 was not. Water-sensitivity is a conservation challenge associated with significant numbers of modern oil paintings and this study aimed to further develop our understanding of the molecular causes of water sensitivity. SEM elemental mapping of samples taken from both swatches provided no indication for the formation of epsomite – a known cause of water sensitivity in some modern oil paintings. Liquid chromatography coupled with mass spectrometry (HPLC-MS) and gas chromatography coupled with mass spectrometry (GC-MS) also revealed very similar qualitative-quantitative composition in terms of unbound and esterified medium fractions. The polymeric network was investigated using analytical pyrolysis. A combination of flash pyrolysis coupled with gas chromatography mass spectrometry (Py-GC-MS) together with evolved gas analysis mass spectrometry (EGA-MS) revealed that the polymeric material was relatively more abundant in the non-water-sensitive paint. This is the first multi-analytical study that has demonstrated a correlation between water-sensitivity and the degree of polymerisation of the oil medium; independent of other known causes of water-sensitivity.

This chapter deals with the application of gas chromatography coupled to mass spectrometry (GC-MS) in the identification of designer drugs and problems that may arise when using it. Gas chromatography is a perfect separating technique but provides no molecular identification information about the chromatographed compound. GC-MS has become a well-established analytical technique in a large variety of forensic applications and is now a method of choice used in many working analytical procedures in forensic laboratories. Derivatization serves several important functions in the GC-MS analysis. Derivatization may also prevent the phenomenon of transesterification, which has been observed when injections of the underivatized drugs have been made with methanol used as a solvent or even spontaneously when stocked in a methanolic solution. Identification of designer drugs using GC-MS is based on mass spectra and retention times of the analyzed compounds. In order to compare the retention times between the analyses or among the instruments, retention time locking is introduced.

Simple SummaryThe waxy layer covering the surface of most terrestrial insects is mainly composed of non-polar lipids termed cuticular hydrocarbons (CHCs). These have a long research history as important dual traits for both desiccation prevention and chemical communication. We analyzed CHC profiles of seven species of the insect order Blattodea (termites and cockroaches) with the most commonly applied chromatographic method, gas-chromatography coupled with mass spectrometry (GC-MS), and the more novel approach of silver-assisted laser desorption/ionization mass spectrometry (Ag-LDI-MS). Comparing these two analytical methods, we demonstrated that the conventional GC-MS approach does not provide enough information on the entire CHC profile range in the tested species. Ag-LDI-MS was able to detect very long-chain CHCs ranging up to C58, which remained undetected when solely relying on standard GC-MS analysis. Additionally, we measured the body surface areas of each tested species applying 3D scanning technology to assess their respective CHC amounts per mm2. When adjusting for body surface areas, proportional CHC quantity distributions shifted considerably between our studied species, suggesting the importance of including this factor when conducting quantitative CHC comparisons, particularly in insects that vary substantially in body size.Most of our knowledge on insect cuticular hydrocarbons (CHCs) stems from analytical techniques based on gas-chromatography coupled with mass spectrometry (GC-MS). However, this method has its limits under standard conditions, particularly in detecting compounds beyond a chain length of around C40. Here, we compare the CHC chain length range detectable by GC-MS with the range assessed by silver-assisted laser desorption/ionization mass spectrometry (Ag-LDI-MS), a novel and rarely applied technique on insect CHCs, in seven species of the order Blattodea. For all tested species, we unveiled a considerable range of very long-chain CHCs up to C58, which are not detectable by standard GC-MS technology. This indicates that general studies on insect CHCs may frequently miss compounds in this range, and we encourage future studies to implement analytical techniques extending the conventionally accessed chain length range. Furthermore, we incorporate 3D scanned insect body surface areas as an additional factor for the comparative quantification of extracted CHC amounts between our study species. CHC quantity distributions differed considerably when adjusted for body surface areas as opposed to directly assessing extracted CHC amounts, suggesting that a more accurate evaluation of relative CHC quantities can be achieved by taking body surface areas into account.

Evaluation of straw with absorbed glycerol thermal degradation during pyrolysis and combustion by TG-FTIR and TG-GC/MS

The Gomeira (Vochysia pyramidalis Mart.), belonging to the family Vochysiaceae, is a plant species from the Brazilian cerrado used in folk medicine because of its reputedly anti-inflammatory, analgesic and anti-bacterial properties. However, scientific data concerning this species are scarce. Therefore, the aim of the present study was to conduct an anatomical and histochemical assessment of this plant species and characterize the chemical composition of its essential oil. For the anatomical evaluation, the leaves, stems and petals were fixed and subjected to common plant anatomy techniques. For the histochemical tests, fresh samples of the stems, leaves and petals were sectioned using a microtome and stained with different dyes to identify the chemical components. The essential oil was obtained from fresh flowers and both dry and fresh leaves using hydrodistillation and was characterized by gas chromatography coupled with mass spectrometry (GC/MS). The anatomical analysis showed several xeromorphic characteristics, which suggest that the mucilaginous channeland idioblasts are the only secretory structures present in this species. The histochemical tests revealed the presence of secondary metabolites belonging to two different chemical classes: the phenolic compounds and terpenes. The chemical composition of the essential oil was analyzed by gas chromatography–mass spectrometry (GC/MS), and hexadecanol; pentacosane and farnesol were identified as its main components. Key words: Brazilian cerrado in Goias state, secretory structures, farnesol, secondary metabolites, terpenes.

Identification of perfumery residues contained in glass objects from Parthian to early Islamic period with gas-chromatography coupled with mass spectroscopy

Event Abstract Back to Event Determination of decomposition-related volatile organic compounds from different pig tissues for environmental and forensic applications Dibyendu Dutta1, 2, Samantha T. Keene1 and Ngee S. Chong1* 1 Middle Tennessee State University, Department of Chemistry, United States 2 New York Medical College, Department of Medicine, United States Research on the decomposition chemistry of porcine tissues is beneficial in environmental and forensic fields. The environmental management issues regarding the disposal of animal carcasses in catastrophic events with large human and livestock casualty require a detailed understanding of degradation by-products that could be released into the environmental media of soil, water, and air. Furthermore, the insights gained from research on decomposition of porcine tissues can be conducive toward the training of cadaver dogs for crime scene investigation, determining the presence of trace chemical evidence of decomposed tissues, and the estimation of postmortem interval (PMI) in homicide investigation. In this project, gas chromatography coupled with mass spectrometry (GC-MS) was used to identify and quantify postmortem volatile organic compounds (VOCs). Different types of pig tissues including skins, bones, muscle, and blood were used to investigate decomposition-related VOCs over a series of time-intervals over a period of 72 days. In blood, ethylbenzene appeared in the initial decomposition stages, and styrene and benzaldehyde peaked till late stages of decomposing. While phenylalanine may be the common source of origin of these compounds in blood, ethylbenzene can undergo dehydrogenation to form styrene, which can later produce benzaldehyde through oxidation. In bones, methanethiol and dimethyl sulfide appear during early decomposing stages, and become undetectable after day 23 due to their subsequent conversion to dimethyl disulfide. Besides being the by-products of bacterial metabolism, these sulfur compounds may also come from chemical degradation of methionine. While dimethyl sulfide and methanethiol can be the direct by-products of methionine degradation, dimethyl sulfide can also be formed by the release of hydrogen sulfide via intermolecular reaction of two methanethiol molecules. The subsequent formation dimethyl disulfide and dimethyl trisulfide was also observed. Thus, ethylbenzene, benzaldehyde, dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide may be used as potential markers for PMI estimation. Keywords: Decomposition chemistry, Postmortem interval (PMI), Volatile organic compounds (V.O.C.), GC-MS (gas chromatography-mass spectrometry), forensic chemistry Conference: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference , Orlando, Florida, United States, 17 Sep - 20 Sep, 2018. Presentation Type: Oral Presentation Topic: Enviornmental and Green Chemistry Citation: Dutta D, Keene ST and Chong NS (2019). Determination of decomposition-related volatile organic compounds from different pig tissues for environmental and forensic applications. Front. Chem. Conference Abstract: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference . doi: 10.3389/conf.fchem.2018.01.00008 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Sep 2018; Published Online: 17 Jan 2019. * Correspondence: Dr. Ngee S Chong, Middle Tennessee State University, Department of Chemistry, Murfreesboro, United States, Ngee.Chong@mtsu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Dibyendu Dutta Samantha T Keene Ngee S Chong Google Dibyendu Dutta Samantha T Keene Ngee S Chong Google Scholar Dibyendu Dutta Samantha T Keene Ngee S Chong PubMed Dibyendu Dutta Samantha T Keene Ngee S Chong Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Gas chromatography coupled with mass spectrometry (GC-MS) using both electron impact and chemical ionization detection modes led to the determination of the volatile composition of two samples of freshly distilled Cognac and two samples of freshly distilled Calvados. A total of 169 volatile compounds were directly identified in dichloromethane extracts obtained by liquid-liquid extraction. Trace compounds present in both spirits were characterized with the help of preparative separations. In a first step, groups of compounds were separated by preparative GC, and the fractions were analyzed on a polar stationary phase by GC-MS. In a second step, silica gel fractionation was used to separate them by polarity. In this study, 331 compounds, of which 162 can be considered as trace compounds, were characterized in both freshly distilled Cognac and Calvados. Of these, 39 are common to both spirits; 30 are specific to Cognac with numerous hexenyl esters and norisoprenoidic derivatives, whereas 93 are specific to Calvados with compounds such as unsaturated alcohols, phenolic derivatives, and unsaturated aldehydes.

A simple, rapid, and sensitive method for the analysis of halothane in biological samples was developed. The procedure describes the extraction of halothane from blood, liver, kidney, brain, urine, bile, and stomach contents by headspace solid-phase microextraction (HS-SPME) followed by capillary gas chromatography coupled with mass spectrometry (GC-MS). The recovery in blood samples after addition of ammonium sulfate and sulfuric acid was 72% compared to a sample prepared in water (100%). Linearity was established over a concentration range of 0.1-100 mg/kg of spiked blood samples with an excellent coefficient of correlation (0.996) and a limit of detection of 0.004 mg/kg. The time for analysis was approximately 40 min per sample including the extraction step. The procedure was used for quantitation of halothane in various samples in a case of a double homicide. HS-SPME in combination with GC-MS was an effective method for the determination and quantitation of halothane in biological material.

The essential oil (EO) of plants of the Poaceae family has diverse chemical constituents with several biological properties. But, data on the chemical constituents and toxicity are still unavailable for some species belonging to this family, such as Euclasta condylotricha Steud (Eu. condylotricha). In this study, the chemical composition of the EOs of Eu. condylotricha flowers was evaluated by gas chromatography coupled with mass spectrometry (GC-MS). The EOs larvicidal property was assessed against third instar larvae of three Anopheles gambiae laboratory strains (Kisumu, Acerkis and Kiskdr) according to the WHO standard protocol. The percentage yields of the EOs obtained from hydro distillation of Eu. condylotricha flowers varied 0.070 to 0.097%. Gas Chromatography-Mass Spectrometry (GC-MS) applied to the EOs revealed fifty-five (55) chemical constituents, representing 94.95% to 97.78% of the total essential oils. Although different chemical profiles of the dominant terpenes were observed for each sample, EOs were generally dominated by sesquiterpenoids with juvenile hormones as the major compounds. The primary compounds were juvenile hormone C16 (JH III) (35.97-48.72%), Methyl farnesoate 10,11-diol (18.56-28.73%), tau-Cadinol (18.54%), and β-Eudesmene (12.75-13.46%). Eu. condylotricha EOs showed a strong larvicidal activity with LC50 values ranging from 35.21 to 52.34 ppm after 24 hours of exposition. This study showed that Eu. Condylotricha flowers essential oils are potent sources of juvenile hormones that could be a promising tool for developing an eco-friendly malaria vector control strategy.