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gas chromatography

S Oliverio, V Varlet
Carbon monoxide is one of the most abundant toxic air pollutants. Symptoms of a CO intoxication are non-specific, leading to a high number of misdiagnosed CO poisoning cases that are missing in the disease statistics. The chemical nature of the molecule makes it difficult to detect for long periods and at low levels, thus requiring a very accurate and sensitive method. Current methods capable of accurate and sensitive analyses are available, however an inconsistency between results and symptoms are frequently reported...
May 18, 2018: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
Dragan Adamović, Jovan Dorić, Mirjana Vojinović Miloradov, Savka Adamović, Sabolč Pap, Jelena Radonić, Maja Turk Sekulić
The results of the research in the field of benzene, toluene, ethylbenzene and xylene isomers (BTEX) concentrations in exhaust gases of spark ignition engines under different operating conditions are presented in this paper. The aim of this paper is to gain a clearer insight into the impact of different engine working parameters on the concentrations of BTEX. The experimental investigation has been performed on the SCHENCK 230 W test stand with the controlled IC engine. The engine operating points have been chosen based on the results of a simulation and they are considered as the typical driving conditions according to the New European Driving Cycle...
May 20, 2018: Science of the Total Environment
Brian J Cook, Gianna N Di Francesco, Matthew T Kieber-Emmons, Leslie J Murray
Oxygenation of a tricopper(I) cyclophanate (1) affords reactive transients competent for C-H bond activation and O atom transfer to various substrates (including toluene, dihydroanthracene, and ethylmethylsulfide) based on 1 H NMR, gas chromatography/mass spectrometry (MS), and electrospray ionization (ESI)/MS data. Low product yields (<1%) are determined for C-H activation substrates (e.g, toluene, ethylbenzene), which we attribute to competitive ligand oxidation. The combined stopped-flow UV/visible, electron paramagnetic resonance, ESI/MS, 1 H NMR, and density functional theory (DFT) results for reaction of 1 with O2 are consistent with transient peroxo- and di(oxo)-bridged intermediates...
May 23, 2018: Inorganic Chemistry
Yu Zhang, Yuping Liu, Wenxi Yang, Jia Huang, Yingqiao Liu, Mingquan Huang, Baoguo Sun, Changlin Li
To characterize potent odor-active compounds in preserved egg yolk (PEY), volatile compounds were isolated by headspace solid-phase microextraction and solvent-assisted flavor evaporation. Gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS) analyses identified a total of 53 odor-active compounds by comparing the odor characteristics, MS data, and retention indices with those of reference compounds. Twenty-seven odorants were detected in at least 5 isolates that were extracted and analyzed by the same method, and their flavor dilution (FD) factors, ranging from 1 to 2048, were measured by aroma extract dilution analysis (AEDA)...
May 23, 2018: Journal of Agricultural and Food Chemistry
Bingjun Han, Ya Li, Bing Qian, Yan He, Lixu Peng, Huamei Yu
A novel detector for liquid chromatography (LC) for the determination of dithiocarbamate (DTC) fungicides is presented with a miniaturized dielectric barrier discharge-microplasma molecular emission spectrometer and an online microwave-assisted hydrolysis reactor. DTCs in the sample/standard solutions together with SnCl2 were pumped to the reactor to be converted to CS2 with high efficiency, which was then separated from the liquid phase and transformed for the detection of the specific molecular emission at 257...
May 23, 2018: Analyst
Zuobing Xiao, Jiancai Zhu
The volatile compounds of jujube (Ziziphus jujube Mill.) puree obtained from three cultivars: 'jinsixiaozao' (Y1), 'youzao' (Y2), and 'yuzao' (Y3) were analyzed by gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry, GC-flame photometric detection, and nitrogen phosphorus detector. The results showed that a total of 37, 37, and 35 odor-active compounds were identified by GC-O in samples of Y1, Y2, and Y3, respectively. In addition, the odor activity value (OAV) was used to determine the important compounds...
May 23, 2018: Journal of Agricultural and Food Chemistry
Wei Zhu, Qian Meng, Huan Zhang, Meng-Long Wang, Xuan Li, Hong-Tuo Wang, Gui-Ling Zhou, Lin Miao, Qi-Lian Qin, Ji-Hong Zhang
Ghost moths inhabiting the alpine meadows of the Tibetan Plateau are cold-adapted stenothermal organisms that are susceptible to heat (dead within 7 days of 27 °C exposure). Exploring the metabolic basis of their heat susceptibility would extend our understanding of the thermal biology of alpine dwelling invertebrates. Here, gas chromatography-mass spectrometry-based metabolomics was combined with physiological and transcriptional approaches to determine the metabolic mechanisms of heat susceptibility in Thitarodes xiaojinensis larvae...
May 23, 2018: Insect Science
Li-Qing Yu, Li-Ya Wang, Fei-Hong Su, Ping-Yu Hao, Huan Wang, Yun-Kai Lv
A stainless steel fiber was coated with a gate-opening controlled metal-organic framework ZIF-7 via a sol-gel method and applied to the solid-phase microextraction of aldehydes (hexanal, heptanal, octanal, nonanal, decanal) from exhaled breath by lung cancer patients. The effects of temperature and time on the sorption and desorption were optimized. Under optimum condition, the modified fiber displays enrichment factors (typically ranging from 300 to 10,000), low limits of detection (0.61-0.84 μg L-1 ), and wide linear ranges of hexanal, heptanal (5-500 μg L-1 ) and octanal, nonanal, decanal (10-1000 μg L-1 )...
May 22, 2018: Mikrochimica Acta
Ankita Asati, G N V Satyanarayana, V Tanmya Srivastava, Devendra K Patel
A simple and rapid method for the extraction of organochlorine compounds (OCs) including poly-chlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in fish liver using ultrasound assisted dispersive liquid-liquid microextraction based on the solidification of floating organic droplet (US-DLLME-SFO) was developed. For reducing the complexity of the matrix, the sample was pre-treated prior to microextraction. Factors affecting US-DLLME-SFO were optimized by using statistical design of experiment (DoE)...
May 17, 2018: Journal of Chromatography. A
Yanping Cao, Dafeng Jiang, Fenghua Li, Jindong Chen, Wei Li, Yanni Jiao, Lu Li
The occurrence and human dietary exposure of 12 dioxin-like polychlorinated biphenyls (DL-PCBs) in 41 marine fish samples from Shandong Province of China were investigated. The DL-PCB congeners were extracted using automated Soxhlet extraction, purified via a composite column cleanup procedure and analyzed by gas chromatography-triple quadrupole mass spectrometry. DL-PCB congeners were found in all analyzed samples, with a mean concentration of 0.887 ng/g ww (wet weight). The TEQ concentrations of DL-PCBs in individual fish samples ranged from 0...
May 22, 2018: Food Additives & Contaminants. Part B, Surveillance
Jessica L Petrick, Paula L Hyland, Patrick Caron, Roni T Falk, Ruth M Pfeiffer, Sanford M Dawsey, Christian C Abnet, Philip R Taylor, Stephanie J Weinstein, Demetrius Albanes, Neal D Freedman, Susan M Gapstur, Gary Bradwin, Chantal Guillemette, Peter T Campbell, Michael B Cook
Background: Esophageal adenocarcinoma (EA) and gastric cardia adenocarcinoma (GCA) are characterized by a strong male predominance. Concentrations of sex steroid hormones have been hypothesized to explain this sex disparity. However, no prospective population-based study has examined sex steroid hormones in relation to EA/GCA risk. Thus, we investigated whether prediagnostic circulating sex steroid hormone concentrations were associated with EA/GCA in a nested case-control study drawn from participants in three prospective cohort studies...
May 17, 2018: Journal of the National Cancer Institute
Manish Kumar, Rohit Bhatia, Ravindra K Rawal
Although excipients are pharmacologically inert substances, still they are integral and significant ingredients of a pharmaceutical formulation. Their amount and concentration level along with the active pharmaceutical ingredients is of utmost importance to decide the pharmacokinetics and stability of a dosage form. It is becoming progressively more important to illustrate the purity of excipients throughout the development and manufacture of pharmaceutical products as the safety and efficacy of the pharmaceutical formulation is largely affected by the quality of excipients...
May 17, 2018: Journal of Pharmaceutical and Biomedical Analysis
Jiwon On, Heesoo Pyo, Seung-Woon Myung
The aim of this study was to optimize the dispersive liquid-liquid microextraction (DLLME) parameters for simultaneous analysis through DLLME-gas chromatography-mass spectrometry (GC-MS) of six iodo-trihalomethanes, four haloacetonitriles, and one halonitromethane, which are residual disinfection products found in drinking water. Eleven disinfection by-product (DBPs) remaining in aqueous samples were extracted and concentrated using a simple, rapid, and environmentally friendly DLLME method, and then analyzed simultaneously by GC-MS...
May 19, 2018: Science of the Total Environment
Marek Łukasz Roszko, Marta Kamińska, Krystyna Szymczyk, Katarzyna Piasecka-Jóźwiak, Beata Chabłowska
The aim of this work was to evaluate the activity of xenobiotic mixtures containing persistent organic pollutants isolated from commercial fish oil samples against sex hormone receptors, including estrogen and androgen. The applied bioassay was based on transgenic yeast strains. The mixtures were extracted from the samples using the semi-permeable membrane dialysis technique and analyzed with gas chromatography/ion trap mass spectrometry. It turned out that mixtures of chemicals isolated from fish oil may interact with human steroid sex hormone receptors in various ways: the tested samples showed both estrogenic and anti-androgenic activity...
2018: PloS One
Christopher L McGann, Grant C Daniels, Spencer L Giles, Robert B Balow, Jorge L Miranda-Zayas, Jeffrey G Lundin, James H Wynne
The threat of chemical warfare agents (CWA) compels research into novel self-decontaminating materials (SDM) for the continued safety of first-responders, civilians, and active service personnel. The capacity to actively detoxify, as opposed to merely sequester, offending agents under typical environmental conditions defines the added value of SDMs in comparison to traditional adsorptive materials. Porous polymers, synthesized via the high internal phase emulsion (HIPE) templating, provide a facile fabrication method for materials with permeable open cellular structures that may serve in air filtration applications...
May 22, 2018: Macromolecular Rapid Communications
Bárbara Viero de Noronha, Márcio Fernando Bergamini, Luiz Humberto Marcolino Junior, Bruno José Gonçalves da Silva
In this study, a simple, efficient, and reusable device based on cellulose membranes modified with polypyrrole was developed to extract 14 emerging contaminants from aqueous matrices. For chemical polymerization, a low-cost cellulose membrane was immersed in 0.1 mol L-1 pyrrole and 0.5 mol L-1 ammonium persulfate for 40 min in an ice/water bath. The cellulose membranes modified with polypyrrole were accommodated in a polycarbonate holder suitable for solid-phase extraction disks. Solid-phase extraction parameters that affect extraction efficiency, such as sample volume, pH, flow-rate, and desorption were optimized...
May 21, 2018: Journal of Separation Science
Brian P Mayer, Carlos A Valdez, Alan J DeHope, Paul E Spackman, Audrey M Williams
Chemical attribution of the origin of an illegal drug is a key component of forensic efforts aimed at combating illicit and clandestine manufacture of drugs and pharmaceuticals. The results of these studies yield detailed information on synthesis byproducts, reagents, and precursors that can be used to identify the method of manufacture. In the present work, chemical attribution signatures (CAS) associated with the synthesis of the analgesic 3-methylfentanyl, N-(3-methyl-1-phenethylpiperidin-4-yl)-N-phenylpropanamide, were investigated...
August 15, 2018: Talanta
Xia Wang, Wan-Ru Sheng, Xiao-Yun Jiao, Ru-Song Zhao, Ming-Lin Wang, Jin-Ming Lin
Metal-organic nanotubes (MONTs) have great potential for solid phase microextraction (SPME) on account of high specific surface area, tunable pore sizes, and exceptional thermal and chemical stability. In this work, zinc (II)-based metal-organic nanotubes (Zn-MONTs) were used as an adsorbent for the SPME of nitro-polycyclic aromatic hydrocarbons (NPAHs) at trace levels from environmental water samples. Gas chromatography-mass spectrometry was used for sample analysis and key factors were investigated and optimized...
August 15, 2018: Talanta
Rebeca López-Serna, David Marín-de-Jesús, Rubén Irusta-Mata, Pedro Antonio García-Encina, Raquel Lebrero, María Fdez-Polanco, Raúl Muñoz
The work here presented aimed at developing an analytical method for the simultaneous determination of 22 pharmaceuticals and personal care products, including 3 transformation products, in sewage and sludge. A meticulous method optimization, involving an experimental design, was carried out. The developed method was fully automated and consisted of the online extraction of 17 mL of water sample by Direct Immersion Solid Phase MicroExtraction followed by On-fiber Derivatization coupled to Gas Chromatography - Mass Spectrometry (DI-SPME - On-fiber Derivatization - GC - MS)...
August 15, 2018: Talanta
Qin Yang, Lu Xu, Li-Juan Tang, Jiang-Tao Yang, Ben-Qing Wu, Nan Chen, Jian-Hui Jiang, Ru-Qin Yu
Metabonomics has been widely used in disease diagnosis and clinically practical methods often require the detection of multi-class bio-samples. In this work, multi-class classification methods were investigated to simultaneously discriminate among 6 inherited metabolic diseases (IMDs) and the normal instances using gas chromatography-mass spectrometry (GC-MS) of urine samples. Two common multi-class classification strategies, one-against-all (OAA) and one-against-one (OAO) were compared and enhanced using a novel ensemble classification strategy (ECS), which developed a set of sequential sub-classifiers by fusion of OAA and OAO and made the final classification decisions using softmax function...
August 15, 2018: Talanta
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