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Ionization Detector (ionization + detector)
Kinds of Ionization Detector Selected AbstractsUsed Motor Oil as a Source of MTBE, TAME, and BTEX to Ground WaterGROUND WATER MONITORING & REMEDIATION, Issue 4 2002Ronald J. Baker Methyl tert-butyl ether (MTBE), the widely used gasoline oxygenate, has been identified as a common ground water contaminant, and BTEX compounds (benzene, toluene, ethylbenzene, and xylenes) have long been associated with gasoline spills. Because not all instances of ground water contamination by MTBE and BTEX can be attributed to spills or leaking storage tanks, other potential sources need to be considered. In this study, used motor oil was investigated as a potential source of these contaminants. MTBE in oil was measured directly by methanol extraction and gas chromatography using a flame ionization detector (GC/FID). Water was equilibrated with oil samples and analyzed for MTBE, BTEX, and the oxygenate tert-amyl methyl ether (TAME) by purge- and-trap concentration followed by GC/FID analysis. Raoult's law was used to calculate oil-phase concentrations of MTBE, BTEX, and TAME from aqueous-phase concentrations. MTBE, TAME, and BTEX were not detected in any of five new motor oil samples, whereas these compounds were found at significant concentrations in all six samples of the used motor oil tested for MTBE and all four samples tested for TAME and BTEX. MTBE concentrations in used motor oil were on the order of 100 mg/L. TAME concentrations ranged from 2.2 to 87 mg/L. Concentrations of benzene were 29 to 66 mg/L, but those of other BTEX compounds were higher, typically 500 to 2000 mg/L. [source] EVALUATION OF GLOBAL YIELD, COMPOSITION, ANTIOXIDANT ACTIVITY AND COST OF MANUFACTURING OF EXTRACTS FROM LEMON VERBENA (ALOYSIA TRIPHYLLA[L'HÉRIT.] BRITTON) AND MANGO (MANGIFERA INDICA L.) LEAVESJOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2007CAMILA G. PEREIRA ABSTRACT In this work, the global yields, composition and antioxidant activity (AA) of extracts from lemon verbena (Aloysia triphylla) and mango (Mangifera indica) leaves obtained by different separation processes were determined. Lemon verbena extracts were obtained by supercritical fluid extraction (SFE), while mango leaf extracts were obtained by SFE, low-pressure solvent extraction (LPSE) and hydrodistillation. The extract's constituents were analyzed by thin-layer chromatography, gas chromatography/mass spectrometry and gas chromatography/flame ionization detector. The AA of the extracts was evaluated by the coupled reaction of , -carotene/linolenic acid. The cost of manufacturing (COM) was estimated for the SFE extracts. Higher global yields were obtained using SFE at 350 bar/45C (1.49%) for lemon verbena and LPSE (3.04%) for mango. The AAs of the extracts were larger than that of the , -carotene for both plants. The minimum values of COM were U.S.$26.96 and 52.45/kg of extract for lemon verbena and mango, respectively. [source] Effect of Storage Time on Raw Sardine (Sardina pilchardus) Flavor and Aroma QualityJOURNAL OF FOOD SCIENCE, Issue 5 2004C. Prost ABSTRACT: Qualitative and semi-relative quantitative changes in flavor profiles associated with the storage of raw sardine (Sardina pilchardus) were investigated. A sensory panel generated a list of 20 odorant descriptors of raw sardine. Forty-seven volatile components were identified by gas chromatography-mass spectrometry and were quantified by gas chromatography-flame ionization detector (GC-FID). Among them, 34 were highlighted as potent odorants using an olfactometric method. (E,E)-2,4-octadienal, E-2-penten-1-ol and 2,3-butanedione are the most potent odorants of raw sardine. The odor-active compounds responsible for oxidized flavors increased during storage, whereas sulfur-containing compounds associated with marine odors decreased. These results could be related to the increase in rancidity aroma and the decrease in marine/iodized aroma identified by the sensory panelists in stored raw fish. [source] Some Examples of Applications of a Microthermal Desorption Device in the Forensic LaboratoryJOURNAL OF FORENSIC SCIENCES, Issue 5 2009Jan Andrasko Ph.D. Abstract:, Several applications of a microthermal desorption device for analysis of small forensic samples are presented. The method uses a solid phase microextraction holder with the fiber removed. In addition to samples of inks on paper, this device was successfully used for analysis of toners, various stains on bank notes, and lipstick stains on paper. Other small items encountered in a forensic science laboratory were also analyzed: particles of smokeless powder, particles of coffee, and automotive clear topcoat layer. The desorbed compounds were analyzed by gas chromatography with a flame ionization detector or by gas chromatography,mass spectrometry. This device can be used in connection with any kind of gas chromatograph. By selection of different injector temperatures, fractionated thermal desorption of samples is achieved. The procedure was demonstrated on samples of ballpoint pen ink of various age. [source] Fast pyrolysis kinetics of expanded polystyrene foamAICHE JOURNAL, Issue 6 2010Pravin Kannan Abstract Fast pyrolysis of polymers, biomass and other substances is of great interest in various applications. For example, in the lost foam casting process, kinetic information about expandable polystyrene (EPS) decomposition under extremely high-heating rate conditions is essential for further process development. A simple laboratory-scale fast pyrolysis technique has been developed and demonstrated for elucidation of EPS decomposition kinetics. Pyrolysis experiments were performed at different reaction temperatures. The cumulative gaseous yields were determined using a flame ionization detector (FID) connected in series with the fast pyrolysis reactor. The governing equations for a semibatch reactor type were modified and applied to obtain kinetic parameters (activation energies and the pre-exponential rate constants) for the EPS decomposition process. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Dynamic control of split flow in packed column supercritical fluid chromatography using dual resistively heated restrictorsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2009Jian Jun Li Abstract Remote control of the vent/detector split flow ratio in packed column supercritical fluid chromatography (pSFC) with flame ionization detector (FID) is demonstrated using a dual heated restrictor method. Restrictors stemming from a Tee at the separation column outlet were, respectively, fixed into an FID and a vent port, and their individual temperatures were controlled using resistively heated wires. Subsequently, both system pressure and split flow could be manipulated. For example, for applied restrictor temperatures examined up to 600°C, corresponding vent/FID split flow ratios between 2 and 7 were observed depending on the port heated. As well, column pressures around 16,23 MPa were also achievable over the same range. Conversely, isobaric altering of the split flow ratio was possible when opposing positive and negative temperature gradients were applied at the two restrictors. Under these conditions, the system pressure varied less than 1% RSD over a 10 min period. As an application, the method was used to establish stable detector operation in the analysis of n -alkanes under pSFC-FID conditions that initiated flame instability. Results indicate that this technique could be a relatively simple and inexpensive means of controlling system pressure and detector split flow ratios in pSFC-FID. [source] Determination of radix ginseng volatile oils at different ages by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2008Yaqiong Qiu Abstract Comprehensive 2-D GC (GC×GC) coupled with TOF MS or flame ionization detector (FID) was employed to characterize and quantify the chemical composition of volatile oil in the radixes of Panax ginseng C. A. Mey. (ginseng) at different ages. Thirty-six terpenoids were tentatively identified based on the MS library search and retention index in a ginseng sample at the age of 3 years. An obvious group-type separation was obtained in the GC×GC-TOF MS chromatogram. The data collected by GC×GC-FID were processed using a principal component analysis (PCA) method to classify the samples at different ages. The compounds responsible for the significant differentiation among samples were defined. It was found that the relative abundances of ,-cadinol, ,-bisabolol, thujopsene, and n -hexadecanoic acid significantly rise with the increase in age. [source] Methyl benzoate as a marker for the detection of mold in indoor building materialsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2005Loay Wady Abstract A convenient analytical method to quantify volatile organic compounds (VOCs) emitted from various building materials has not been addressed yet. This work presents a new and rapid automated method using SPME combined with GC/MS. Methyl benzoate , as a metabolic biomarker for mold growth,was used to indicate VOCs and to determine and assess mold growth on damp samples. Gypsum board and wallboard paper were used as examples of common indoor building materials. Optimized extraction conditions were carried out manually, using a GC/flame ionization detector. Moldy samples were analyzed using an automated SPME-GC/MS analysis under optimized conditions. The amount of methyl benzoate emitted from the studied samples ranged from 32 to 46 ppb, where the density of the fungal biomass was found to be 8×104 cells/mL. A relationship between the amount of fungal biomass and the emitted concentration of methyl benzoate was found and assessed based upon cultured mold samples taken from indoor building sites. The analytical method shows promise for the compound methyl benzoate, which can easily be identified at low detection limits (LOD = 3 ppb) and good linearity (> 0.988), and its extraction and detection can be accomplished cleanly by current extraction techniques. Results suggest that this method with easy sample preparation can be used for quantitation and, of importance, minimal matrix effects are observed. [source] Alcohol-Induced Lipid and Morphological Changes in Chick Retinal DevelopmentALCOHOLISM, Issue 5 2004Yolanda Aguilera Abstract: Background: Alcohol exposure causes alterations in the lipid content of different organs and a reduction of long-chain fatty acids. During embryo development, the central nervous system is extremely vulnerable to the teratogenic effects of alcohol, and the visual system is particularly sensitive. Methods: White Leghorn chick embryos were injected with 10- and 20-,l alcohol doses into the yolk sac at day 6 of incubation. The lipid composition of the retina was analyzed in embryos at day 7 of incubation (E7), E11, E15, and E18. The percentages of phospholipids, free cholesterol, esterified cholesterol, diacylglycerides, and free fatty acids were estimated by using an Iatroscan thin layer chromatography flame ionization detector. Gas chromatography and mass spectrometry were used to determine fatty acid composition. The morphological study was performed at E7, E11, and E19 by means of semithin and immunohistochemical techniques. Results: In the retina, alcohol causes the total lipid content to change, with a remarkable increase in free cholesterol and a dramatic decrease in esterified cholesterol. Diacylglycerides and free fatty acids tend to increase. Phosphatidylcholine and phosphatidylethanolamine decrease, whereas phosphatidylserine, sphingomyelin, and phosphatidylinositol increase. The main fatty acids of the retina also undergo changes. At E7, myriotic acid increases, and oleic acid and polyunsaturated fatty acids such as arachidonic acid and docosahexaenoic acid decrease. From E18 onward, there is some recovery, except for fatty acids, which recover earlier. From a morphological point of view, alcohol effects on retinal development are various: increase of intercellular spaces in all cell layers, pyknosis with loss of cellularity in the inner nuclear cell layer and ganglion cell layer, retarded or disorderly cell migration, early cell differentiation, and loss of immunoreactivity for myelin oligodendrocyte,specific protein. Conclusions: Acute alcohol exposure during embryo development causes the lipid composition of the retina to change, with a trend to recovery in the last stages. These alterations are in line with the changes observed at a morphological level. [source] Determination of curcumol in rat plasma by capillary gas chromatography with a hydrogen flame ionization detectorBIOMEDICAL CHROMATOGRAPHY, Issue 4 2010Xiao Zhao Abstract A simple and sensitive capillary gas chromatography with a hydrogen flame ionization detector (GC-FID) method was developed for the determination of curcumol in rat plasma. From a variety of compounds and solvents tested, buagafuran was selected as the internal standard (IS) and acetonitrile was found to be the best protein precipitation agent and solvent for extracting curcumol from plasma and tissues samples. (Buagafuran was used as an internal standard. Curcumol was extracted by a protein precipitation with acetonitrile.) The samples were determined by GC on an HP-5 column (30.0 m × 0.32 mm, 0.25 ,m); inlet volume 2 ,L; split ratio 10 : 1; inlet temperature 250°C; oven temperature 180°C; flow 1.0 mL/·min; FID 250°C; carrier gas N2. The resulting retention times of curcumol and IS were 6.0 and 9.5 min. There was good linearity over the range 0.133,133.3 ,g/mL (r = 0.9999) in plasma samples. The method recoveries were 97.7,102.0% in plasma, and the intra- and inter-day variances (RSD) were less than 15% in all cases. The GC method was applied to develop a pharmacokinetics study in which experimental rats received a single administration of curcumol by intravenous injection. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of community structure through deconvolution of PLFA-FAME signature of mixed populationBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2007Dipesh K. Dey Abstract Phospholipid fatty acids (PLFAs) as biomarkers are well established in the literature. A general method based on least square approximation (LSA) was developed for the estimation of community structure from the PLFA signature of a mixed population where biomarker PLFA signatures of the component species were known. Fatty acid methyl ester (FAME) standards were used as species analogs and mixture of the standards as representative of the mixed population. The PLFA/FAME signatures were analyzed by gas chromatographic separation, followed by detection in flame ionization detector (GC-FID). The PLFAs in the signature were quantified as relative weight percent of the total PLFA. The PLFA signatures were analyzed by the models to predict community structure of the mixture. The LSA model results were compared with the existing "functional group" approach. Both successfully predicted community structure of mixed population containing completely unrelated species with uncommon PLFAs. For slightest intersection in PLFA signatures of component species, the LSA model produced better results. This was mainly due to inability of the "functional group" approach to distinguish the relative amounts of the common PLFA coming from more than one species. The performance of the LSA model was influenced by errors in the chromatographic analyses. Suppression (or enhancement) of a component's PLFA signature in chromatographic analysis of the mixture, led to underestimation (or overestimation) of the component's proportion in the mixture by the model. In mixtures of closely related species with common PLFAs, the errors in the common components were adjusted across the species by the model. Biotechnol. Bioeng. 2007;96: 409,420. © 2006 Wiley Periodicals, Inc. [source] | ||||||||||