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Sample records for carbowax

  1. 新型溶胶-凝胶气相色谱柱:聚甲基苯基硅氧烷柱、Carbowax柱及PEG-Silane柱%New Members in the Family of the Sol-gel Columns for Gas Chromatography:PMPS Column, Carbowax Column and PEG-Silane Column

    Institute of Scientific and Technical Information of China (English)

    王东新

    2004-01-01

    采用聚甲基苯基硅氧烷、Carbowax 20M、PEG-silane为固定相制取了溶胶-凝胶气相色谱毛细管柱.在这些色谱柱上脂肪酸、酚类、胺和苯胺类、醇、醛等各类化合物都得到很好的分离.采用这些固定相的溶胶-凝胶柱对化合物的分离也表现出很好的重现性.溶胶-凝胶法制柱对各类固定相是普遍适用的方法.

  2. Determination of solubility parameters and thermodynamic properties in hydrocarbon-solvent systems by gas chromatography

    Directory of Open Access Journals (Sweden)

    E. Díaz

    2007-06-01

    Full Text Available Gas chromatography used to calculate the specific retention volume of several hydrocarbons in different chromatographic liquid phases (Squalane, Carbowax-400, Carbowax-1500, Carbowax-4000, Amine-220, Dinonyl phthalate, Tributyl phosphate and Trixylenyl phosphate. Some thermodynamic parameters, such as enthalpy of sorption and Flory-Huggins parameters relating the interaction between liquid phases and solutes, were also calculated from the determined retention volumes. Liquid phase solubility parameters of Squalane, Carbowax-400, Carbowax-1500 and Carbowax-4000 at 80 ºC as well as the polar and apolar components were calculated too. A new model was proposed to correlate polar contribution to the solubility parameter of a liquid phase with the specific retention volume of a solute in this liquid phase.

  3. Overview of Poisoning

    Science.gov (United States)

    ... Carbowax (polyethylene glycol) Carboxymethylcellulose (dehydrating material packed with film, books, and other products) Castor oil Cetyl alcohol ( ... related fracture... More News News HealthDay Which High School Sport Has the Most Concussions? WEDNESDAY, March 15, ...

  4. EFFECT OF EMBEDDING METHODS VERSUS FIXATIVE TYPE ON KARYOMETRIC MEASURES

    NARCIS (Netherlands)

    BOON, ME; VANDERPOEL, HG; TAN, CJA; KOK, LP

    1994-01-01

    The influence of fixation and embedding methods in seven urologic tumor samples was studied karyometrically for 12 preparatory techniques. Routine histologic formalin fixation was compared with Carbowax and Kryofix fixatives. Also, histologic material was studied embedded in paraffin and plastic (GM

  5. Ullage Tank Fuel-Air Mixture Characterisation

    Science.gov (United States)

    2011-12-01

    be classified into polar (e.g., polyacrylate ) and non-polar (e.g., polydimethylsiloxane [PDMS]) coatings. The analytes are extracted and... Polyacrylate (PA) 85 polar semi-volatiles Carbowax/DVB (CW/DVB) 65 polar compounds CW/PDMS 75 low-molecular weight compound PDMS/DVB 50/30 flavour

  6. Proceedings of Symposium on Analysis and Detection of Explosives (3rd) Held in Mannheim-Neuostheim (Germany, F.R.) on 10-13 July 1989

    Science.gov (United States)

    1989-07-13

    Packard 5880 equipped with flame ionisatin detector. Column is a 12 rn 0,2 mm internal diameter glass capillary coated with deactivated carbowax OV 101...Sianori , G. Terzaghi§ * Dipartimento di Chimica Generale dell’Universita’ di Pavia, Viale Taramelli, 12. I 27100 Pavia. Italia. Istituto di Medicina ...Legale dell’Unlversita’ di Brescia. c/o Ospedali Civili, Piazza Ospedali. I 25100, Brescia - Italia- S Dipartimento di ChImica Fisica ed

  7. Abnormal Metabolite in Alcoholic Subjects,

    Science.gov (United States)

    1982-01-01

    coated with 3Z Carbowax 20 M. Serum proteins were removed by precipitation with 0.5 M percholoric acid. The clear, protein -free supernatant was...this study included alcoholic hepatitis or cirrhosis of the liver in 29. of the alcoholic subjects; diabetes mellitus in 8 and Korsakoff’s syndrome in 6...no ethanol, and who according to the history had been two days without any alcohol intake . DISCUSSION The source of the 2,3-butanediol found in the

  8. Strength Loss in MA-MOX Green Pellets from Radiation Damage to Binders

    Energy Technology Data Exchange (ETDEWEB)

    Paul A. Lessing; W.R. Cannon; Gerald W. Egeland; Larry D. Zuck; James K. Jewell; Douglas W. Akers; Gary S. Groenewold

    2013-06-01

    The fracture strength of green Minor Actinides (MA)-MOX pellets containing 75 wt.% DUO2, 20 wt. % PuO2, 3 wt. % AmO2 and 2 wt. % NpO2 was studied as a function of storage time, after mixing in the binder and before sintering, to test the effect of radiation damage on binders. Fracture strength degraded continuously over the 10 days of the study for all three binders studied: PEG binder (Carbowax 8000), microcrystalline wax (Mobilcer X) and Styrene-acrylic copolymer (Duramax B1022) but the fracture strength of Duramax B1022 degraded the least. For instance, for several hours after mixing Carbowax 8000 with MA MOX, the fracture strength of a pellet was reasonably high and pellets were easily handled without breaking but the pellets were too weak to handle after 10 days. Strength measured using diametral compression test showed strength degradation was more rapid in pellets containing 1.0 wt. % Carbowax PEG 8000 compared to those containing only 0.2 wt. %, suggesting that irradiation not only left the binder less effective but also reduced the pellet strength. In contrast the strength of pellets containing Duramax B1022 degraded very little over the 10 day period. It was suggested that the styrene portion of the Duramax B1022 copolymer provided the radiation resistance.

  9. Strength loss in MA-MOX green pellets from radiation damage to binders

    Energy Technology Data Exchange (ETDEWEB)

    Lessing, Paul A. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Cannon, W. Roger, E-mail: wrogercannon@gmail.com [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Egeland, Gerald W.; Zuck, Larry D.; Jewell, James K.; Akers, Douglas W.; Groenewold, Gary S. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

    2013-06-15

    The fracture strength of green Minor Actinides (MA)-MOX pellets containing 75 wt.% DUO{sub 2}, 20 wt.% PuO{sub 2}, 3 wt.% AmO{sub 2} and 2 wt.% NpO{sub 2} was studied as a function of storage time, after mixing with the binder and before sintering, to test the effect of radiation damage on binders. Fracture strength degraded continuously over the 10 days of the study for all three binders studied: PEG binder (Carbowax 8000), microcrystalline wax (Mobilcer X) and styrene–acrylic copolymer (Duramax B1022) but the fracture strength of Duramax B1022 degraded the least. For instance, for several hours after mixing Carbowax 8000 with MA-MOX, the fracture strength of a pellet was reasonably high and pellets were easily handled without breaking but the pellets were too weak to handle after 10 days. Strength measured using diametral compression test showed that strength degradation was more rapid in pellets containing 1.0 wt.% Carbowax PEG 8000 compared to those containing only 0.2 wt.%, suggesting that irradiation not only left the binder less effective but also reduced the pellet strength. In contrast the strength of pellets containing Duramax B1022 degraded very little over the 10 days period. It was suggested that the styrene portion present in the Duramax B1022 copolymer provided the radiation resistance.

  10. Strength loss in MA-MOX green pellets from radiation damage to binders

    Science.gov (United States)

    Lessing, Paul A.; Cannon, W. Roger; Egeland, Gerald W.; Zuck, Larry D.; Jewell, James K.; Akers, Douglas W.; Groenewold, Gary S.

    2013-06-01

    The fracture strength of green Minor Actinides (MA)-MOX pellets containing 75 wt.% DUO2, 20 wt.% PuO2, 3 wt.% AmO2 and 2 wt.% NpO2 was studied as a function of storage time, after mixing with the binder and before sintering, to test the effect of radiation damage on binders. Fracture strength degraded continuously over the 10 days of the study for all three binders studied: PEG binder (Carbowax 8000), microcrystalline wax (Mobilcer X) and styrene-acrylic copolymer (Duramax B1022) but the fracture strength of Duramax B1022 degraded the least. For instance, for several hours after mixing Carbowax 8000 with MA-MOX, the fracture strength of a pellet was reasonably high and pellets were easily handled without breaking but the pellets were too weak to handle after 10 days. Strength measured using diametral compression test showed that strength degradation was more rapid in pellets containing 1.0 wt.% Carbowax PEG 8000 compared to those containing only 0.2 wt.%, suggesting that irradiation not only left the binder less effective but also reduced the pellet strength. In contrast the strength of pellets containing Duramax B1022 degraded very little over the 10 days period. It was suggested that the styrene portion present in the Duramax B1022 copolymer provided the radiation resistance.

  11. Comparative study of different fabric phase sorptive extraction sorbents to determine emerging contaminants from environmental water using liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Lakade, Sameer S; Borrull, Francesc; Furton, Kenneth G; Kabir, Abuzar; Fontanals, Núria; Marcé, Rosa Maria

    2015-11-01

    A new sorptive extraction technique, fabric phase sorptive extraction (FPSE), using different coating chemistries: non-polar sol-gel poly(dimethyldiphenylsiloxane) (PDMDPS), medium polar sol-gel poly(tetrahydrofuran) (PTHF), and polar sol-gel poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG triblock) and sol-gel Carbowax 20 M were evaluated to extract a group of pharmaceuticals and personal care products (PPCPs) with wide range of polarity from environmental aqueous samples. Different parameters affecting FPSE such as sample pH, stirring speed, addition of salt, extraction time, sample volume, elution solvent and desorption time were optimized for each sorbent coated FPSE media. Under optimum conditions, FPSE media coated with sol-gel Carbowax 20 M provided the highest absolute recoveries (77-85%) for majority of the analytes with the exception of the most polar ones. Nevertheless, all four sorbents offered better recovery compared to the commercially available coating for stir-bar sorptive extraction based on Ethylene Glycol/Silicone (EG/Silicone). The method based on FPSE with sol-gel Carbowax 20 M media and liquid chromatography-(electrospray ionization) tandem mass spectrometry (LC-(ESI) MS/MS) was developed and validated for environmental water samples. Good apparent recoveries (41-80%), detection limits (1-50 ng L(-1)), repeatability (%RSD<15%, n=5) and reproducibility (%RSD<18%, n=5) were achieved.

  12. Screening of Brazilian fruit aromas using solid-phase microextraction-gas chromatography-mass spectrometry.

    Science.gov (United States)

    Augusto, F; Valente, A L; dos Santos Tada, E; Rivellino, S R

    2000-03-17

    Manual headspace solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was used for the qualitative analysis of the aromas of four native Brazilian fruits: cupuassu (Theobroma grandiflorum, Spreng.), cajá (Spondias lutea. L.), siriguela (Spondias purpurea, L.) and graviola (Anona reticulata, L). Industrialized pulps of these fruits were used as samples, and extractions with SPME fibers coated with polydimethylsiloxane, polyacrylate, Carbowax and Carboxen were carried out. The analytes identified included several alcohols, esters, carbonyl compounds and terpernoids. The highest amounts extracted, evaluated from the sum of peak areas, were achieved using the Carboxen fiber.

  13. Essential oils of camphor tree (cinnamomum camphora nees & eberm cultivated in Southern Brazil

    Directory of Open Access Journals (Sweden)

    Caren D. Frizzo

    2000-01-01

    Full Text Available The essential oils of two varieties of Camphor tree (Cinnamomum camphora Nees & Eberm, Lauraceae, known as Hon-Sho and Ho-Sho cultivated in experimental stands in Southern Brazil were studied. The essential oils were obtained from the leaves and twigs of young plants by hydrodistillation. The identification of the components was performed using GC, GC/MS and retention indexes on methyl silicone and carbowax phases. The main components identified were linalool in the Ho-Sho and camphor in the Hon-Sho.Os óleos essenciais de duas variedades da árvore canforeira (Cinnamomum camphora Nees & Eberm, Lauraceae, conhecidas como Hon-Sho e Ho-Sho cultivadas em canteiros experimentais no sul do Brasil foram estudados. Os óleos essenciais foram obtidos das folhas e ramos de plantas jovens por hidrodestilação. A identificação dos componentes foi feita por GC, GC/MS e índices de retenção nas fases metil silicone e carbowax. Os principais componentes foram linalol no Ho-Sho e cânfora no Hon-Sho.

  14. Determination of N-methylpyrrolidone in lubricating oil samples by g. c

    Energy Technology Data Exchange (ETDEWEB)

    Bhagat, S.D.; Aswal, D.S.; Badoni, R.P.

    1989-06-01

    A rapid gas chromatographic procedure has been developed for quantitative estimation of N-methyl-2-pyrrolidone (NMP) in extract and raffinate phases of lubricating oil extraction processes. Column backflush technique or lubricating oil trap devices were the two approaches used to avoid the interference of lube hydrocarbons with the normal analysis of NMP. The proposed method is based on an internal standardization technique applying tetralin as a reference compound. NMP content was determined from the calibration curve drawn with known weight ratios of NMP and tetralin against the corresponding area ratios. Carbowax 20 M was found to be the best analytical column for separation and quantitation work, whereas a non-polar phase OV-101 was used as lube retainer. FID and TCD systems were employed to cover a wide concentration range from traces to high percentages of NMP. 8 refs., 2 figs., 2 tabs.

  15. Application of solid-phase microextraction combined with derivatization to the enantiomeric determination of amphetamines.

    Science.gov (United States)

    Cháfer-Pericás, C; Campíns-Falcó, P; Herráez-Hernández, R

    2006-03-18

    The utility of combining chiral derivatization and solid-phase microextraction (SPME) for the enantiomeric analysis of primary amphetamines by liquid chromatography has been investigated. Different derivatization/extraction strategies have been evaluated and compared using the chiral reagent o-phthaldialdehyde (OPA)-N-acetyl-l-cysteine (NAC) and fibres with a Carbowax-templated resin coating. Amphetamine, norephedrine and 3,4-methylenedioxyamphetamine (MDA) were used as model compounds. On the basis of the results obtained, a new method is presented based on the derivatization of the analytes in solution followed by SPME of the OPA-NAC derivatives formed. The proposed conditions have been applied to determine the compounds of interest at low ppm levels (urine samples. Data on the linearity, reproducibility, sensitivity and selectivity are given. The utility of the described procedure for the quantification of amphetamine, norephedrine and MDA enantiomers in different kind of samples is also discussed.

  16. Gas chromatographic analysis of methyl formate and application in methanol poisoning cases

    Energy Technology Data Exchange (ETDEWEB)

    Fraser, A.D.; MacNeil, W. (Dalhousie Univ., Halifax, Nova Scotia (Canada))

    A modified headspace gas chromatographic method for analysis of formate in biological fluids is described. Serum or whole blood specimens were methylated in the presence of concentrated sulfuric acid and sodium propionate (internal standard) dissolved in methanol. Derivatization was performed at 35{degree}C for 30 min before injection (0.5 mL headspace) onto a Hallcomid-Carbowax packed GLC column. Using serum or aqueous standards, the method was linear from 5 to 100 mg/dL. The limit of detection was 2.5 mg/dL. Day-to-day precision was less than 5% (CV) at 54 mg/dL formate. Formate and methanol were analyzed in 3 methanol poisonings, two of which were fatal. Formate analysis is considered important in any patient with suspected methanol poisoning who presents for medical assistance with metabolic acidosis. The extent of ocular toxicity correlates better with formate concentration than with methanol concentration.

  17. Determination of acrylamide in food by solid-phase microextraction coupled to gas chromatography-positive chemical ionization tandem mass spectrometry.

    Science.gov (United States)

    Lee, Maw-Rong; Chang, Li-Yo; Dou, Jianpeng

    2007-01-16

    A method has been developed to determine acrylamide in aqueous matrices by using direct immersion solid-phase microextraction (SPME) coupled to gas chromatography-positive chemical ionization tandem mass spectrometry (GC-PCI-MS-MS) in the selected reaction monitoring (SRM) mode. The optimized SPME experimental procedures to extract acrylamide in water solutions were: use of a carbowax/divinylbenzene (CW/DVB)-coated fiber at pH 7, extraction time of 20 min and analyte desorption at 210 degrees C for 3 min. A detection limit of 0.1 microg L(-1) was obtained. The linear range was 1-1000 microg L(-1). The relative standard deviation was 10.64% (n=7). The proposed analytical method was successfully used for the quantification of trace acrylamide in foodstuffs such as French fries (1.2 microg g(-1)) and potato crisps (2.2 microg g(-1)).

  18. High-molecular products analysis of VOC destruction in atmospheric pressure discharge

    Science.gov (United States)

    Grossmannova, Hana; Ciganek, Miroslav; Krcma, Frantisek

    2007-04-01

    We investigate the issue of applicability of the solid phase microextraction (SPME) in the analysis of volatile organic compounds (VOCs) destruction products in the gliding arc discharge. Our research is focused on the measurements with the simple one stage gliding arc reactor, applied voltage was varied in the range of 3.5-4 kV. As a carrier gas, the dry air and its mixtures with nitrogen and oxygen, enriched by toluene, with flow rate of 1000-3500 ml/min was used. Total decomposition of toluene of 97 % was achieved at the oxygen content in carrier gas of 60 %. For measurements with air as a carrier gas, the highest efficiency was 95 %. We also tested the SPME technique suitability for the quantitative analysis of exhausts gases and if this technique can be used efficiently in the field to extract byproducts. Carbowax/divinylbenzene and Carboxen/polydimethylsiloxane/divinylbenzene fibres were chosen for sampling. Tens of various high-molecular substances were observed, especially a large number of oxygenous compounds and further several nitrogenous and CxHy compounds. The concentrations of various generated compounds strongly depend on the oxygen content in gas mixture composition. The results showed that the fiber coated by Carbowax/divinylbenzene can extract more products independently on the used VOC compound. The Carboxen/polydimethylsiloxane/divinylbenzene fiber is useful for the analysis of oxygenous compounds and its use will be recommended especially when the destruction is done in the oxygen rich atmosphere. With the higher ratio of oxygen in the carrier gas a distinctive decline of CxHy compounds amount have been observed. We also tried to describe the significant production of some compounds like benzyl alcohol, benzeneacetaldehyde, even in oxygen content is proximate 0 %. Experimental data demonstrated that it is necessary to use several SPME fibres for full-scale high-molecular products analysis.

  19. Microfibers for juice analysis by solid-phase microextraction Microfibras para análises de sucos por microextração em fase sólida

    Directory of Open Access Journals (Sweden)

    Renata Borchetta Fernandes Fonseca

    2008-12-01

    Full Text Available In view of the interest in analyzing volatile compounds by SPME, the following five microfibers were tested, polydimethylsiloxane; polyacrylate; polydimethylsiloxane/divinylbenzene; carboxen/polydimethylsiloxane, and carbowax/divinylbenzene, to select the one which presents the best performance for the adsorption of the volatile compounds present in the headspace of acid lime juice samples. Sample stabilization time variations (30 and 60 minutes were assessed as well the addition of NaCl to the samples. It was verified that the chromatogram with the most adsorbed volatile compounds was obtained with PDMS/DVB microfiber at 30 minutes and the addition of 0.2 g NaCl.Diante do interesse de analisar substâncias voláteis pelo método de Microextração em Fase Sólida (MEFS, foram testadas cinco microfibras de polidimetilsiloxano - PDMS; poliacrilato - PA; polidimetilsiloxano/divinilbenzeno - PDMS/DVB; carboxen/polidimetilsiloxano CAR/PMDS e carbowax/divinilbenzeno - CW/DVB no presente trabalho, a fim de selecionar a microfibra de melhor desempenho para a adsorção das substâncias voláteis presentes no headspace das amostras de suco de lima ácida (Citrus latifolia, Tanaka cv. Tahiti, obtida por cultivo biodinâmico. As microfibras selecionadas foram PDMS/DVB e PDMS, por apresentarem cromatogramas com maior número de componentes, onde não houve adição prévia de NaCl. A seguir, as microfibras de PDMS/DVB e PDMS foram avaliadas variando-se o tempo de estabilização da amostra (30 e 60 minutos, bem como a adição de NaCl. Verificou-se que o cromatograma com mais substâncias voláteis adsorvidas foi obtido com o uso da microfibra de PDMS/DVB, no tempo de 30 minutos e com a adição de 0,2 g de NaCl.

  20. TREATMENT BY ALTERNATIVE METHODS OF REGRESSION GAS CHROMATOGRAPHIC RETENTION INDICES OF 35 PYRAZINES

    Directory of Open Access Journals (Sweden)

    Fatiha Mebarki

    2016-02-01

    Full Text Available The study treated two closer alternative methods of which the principal characteristic: a non-parametric method (the least absolute deviation (LAD and a traditional method of diagnosis OLS.This was applied to model, separately, the indices of retention of the same whole of 35 pyrazines (27 pyrazines with 8 other pyrazines in the same unit eluted to the columns OV-101 and Carbowax-20M, by using theoretical molecular descriptors calculated using the software DRAGON. The detection of influential observations for non-parametric method (LAD is a problem which has been extensively studied and offers alternative dicapproaches whose main feature is the robustness.here is presented and compared with the standard least squares regression .The comparison between methods LAD and OLS is based on the equation of the hyperplane, in order to confirm the robustness thus to detect by the meaningless statements and the points of lever and validated results in the state approached by the tests statistics: Test of Anderson-Darling, shapiro-wilk, Agostino, Jarque-Bera, graphic test (histogram of frequency and the confidence interval thanks to the concept of robustness to check if the distribution of the errors is really approximate.

  1. AgarCyto: a novel cell-processing method for multiple molecular diagnostic analyses of the uterine cervix.

    Science.gov (United States)

    Kerstens, H M; Robben, J C; Poddighe, P J; Melchers, W J; Boonstra, H; de Wilde, P C; Macville, M V; Hanselaar, A G

    2000-05-01

    In diagnostic cytology, it has been advocated that molecular techniques will improve cytopathological diagnosis and may predict clinical course. Ancillary molecular techniques, however, can be applied only if a sufficient number of preparations are made from a single cell sample. We have developed the AgarCyto cell block procedure for multiple molecular diagnostic analyses on a single scraping from the uterine cervix. The optimized protocol includes primary fixation and transport in ethanol/carbowax, secondary fixation in Unifix, and embedding in 2% agarose and then in paraffin according to a standard protocol for biopsies. More than 20 microscopic specimens were produced from a single AgarCyto cell block, and standard laboratory protocols have been successfully applied for H&E staining, immunohistochemistry for Ki-67 and p53, and in situ hybridization for the centromere of human chromosome 1 and human papilloma virus Type 16. In addition, single AgarCyto sections yielded sufficient input DNA for specific HPV detection and typing by LiPA-PCR, and the protocol includes an option for DNA image cytometry. The AgarCyto cell block protocol is an excellent tool for inventory studies of diagnostic and potentially prognostic molecular markers of cervical cancer.

  2. Detection of Landmine Signature using SAW-based Polymer-coated Chemical Sensor

    Directory of Open Access Journals (Sweden)

    O. K. Kannan

    2004-07-01

    Full Text Available The explosive charge within a landmine is the source for a mixture of chemical vapours that form a distinctive chemical signature indicative of a landmine. The concentrations of these compounds in the air over landmines is extremely low (parts-per-trillion or lower, well below the minimum detection limits of most field-portable chemical sensors. This paper describes a portable  surface acoustic wave-based polymer-coated sensor for the detection of hidden explosives. The sensitivity and selectivity of polymer-based sensors depend on several factors including the chemo-selective coating used, the physical properties of the vapour(s of interest, the selected transducers, and the operating conditions. The polymer-based sensor was calibrated in the  laboratory using the explosive vapour generator. The preliminary results indicated that the carbowax 1000 could be a very good chemical interface to sense low levels of chemical signature of explosive material. Response for 50 ppb of TNT vapours was observed to be 400 Hz for an exposure of 2 min.

  3. Application of solid-phase microextraction combined with derivatization to the determination of amphetamines by liquid chromatography.

    Science.gov (United States)

    Cháfer-Pericás, C; Campíns-Falcó, P; Herráez-Hernández, R

    2004-10-15

    This work evaluates the utility of solid-phase microextraction (SPME) in the analysis of amphetamines by liquid chromatography (LC) after chemical derivatization of the analytes. Two approaches have been tested and compared, SPME followed by on-fiber derivatization of the extracted amphetamines, and solution derivatization followed by SPME of the derivatives formed. Both methods have been applied to measure amphetamine (AP), methamphetamine (MA), and 3,4-methylenedioxymethamphetamine (MDMA), using the fluorogenic reagent 9-fluorenylmethyl chloroformate (FMOC) and carbowax-templated resin (CW-TR)-coated fibers. Data on the application of the proposed methods for the analysis of different kind of samples are presented. When analyzing aqueous solutions of the analytes, both approaches gave similar analytical performance, but the sensitivity attainable with the solution derivatization/SPME method was better. The efficiencies observed when processing spiked urine samples by the SPME/on-fiber derivatization approach were very low. This was because the extraction of matrix components into the fiber coating prevented the extraction of the reagent. In contrast, the efficiencies obtained for spiked urine samples by the solution derivatization/SPME approach were similar to those obtained for aqueous samples. Therefore, the later method would be the method of choice for the quantification of amphetamines in urine.

  4. Fatty acid composition of seed oils from sixAdansonia species with particular reference to cyclopropane and cyclopropene acids.

    Science.gov (United States)

    Ralaimanarivo, A; Gaydou, E M; Bianchini, J P

    1982-01-01

    The oil content of sixAdansonia species (Bombacaceae family) of Madagascar (Adansonia grandidieri, A. za, A. digitata, A. fony, A. madagascariensis andA. suarenzensis) and Africa (A. digitata) ranges from 8 to 46%. All the oils give a positive response to the Halphen test. Malvalic, sterculic and dihydrosterculic acids were detected using gas liquid chromatography-mass spectrometry (GLC-MS). Epoxy or hydroxy fatty acids were not found in these oils. Fatty acid composition was determined by GLC using glass capillary columns coated with BDS and Carbowax 20 M. Results obtained for cyclopropenic fatty acids (CPEFA) were compared to those given by glass capillary GLC after derivatization with silver nitrate in methanol, by hydrogen bromide titration and by proton magnetic resonance (PMR). Good agreement was observed for the results given by the various methods. Malvalic acid content ranges from 3 to 28%, sterculic acid from 1 to 8% and dihydrosterculic acid from 1.5 to 5.1%. Odd-numbered fatty acids (Pentadecanoic and hepatadecanoic) were also observed in minute amounts (0.1-1.1%). Among the normal fatty acids, we observed mainly palmitic (21-46%), oleic (15-40%) and linoleic (12-32%). The relationship between fatty acid composition andAdansonia species is discussed.

  5. Design of the extraction process for terpenes and other volatiles from allspice by solid-phase microextraction and hydrodistillation.

    Science.gov (United States)

    Bajer, Tomáš; Ligor, Magdalena; Ligor, Tomasz; Buszewski, Bogusław

    2016-02-01

    Methods for the separation and determination of terpenes (mono- and sesqui-) and phenylpropanoids such as eugenol and methyleugenol from samples of allspice berries have been developed. Chromatographic analyses of isolated groups of compounds were carried out by means of gas chromatography coupled with mass spectrometry. A comparison of various types of solid-phase microextraction fibers was performed. The highest yields of terpenes were extracted by polydimethylsiloxane and divinylbenzene/Carboxen/polydimethylsiloxane fibers (almost the same for these two fibers), approximately twice as much as by Carbowax/divinylbenzene fiber. The highest amounts of monoterpenes were extracted by divinylbenzene/Carboxen/polydimethylsiloxane fiber, and the highest amounts of sesquiterpenes were extracted by polydimethylsiloxane fiber. Moreover, the effect of water addition on extraction yields as well as time and temperature of extraction were tested. Aroma profiles of extracts obtained by solid-phase microextraction and essential oil obtained by hydrodistillation of allspice berries were compared. The aroma profile of the divinylbenzene/Carboxen/polydimethylsiloxane fiber extract was similar to the aroma profile of essential oil. Particular characteristics of volatile allspice matters were presented. The linear retention indices for each compound were calculated.

  6. Applying Convolution-Based Processing Methods To A Dual-Channel, Large Array Artificial Olfactory Mucosa

    Science.gov (United States)

    Taylor, J. E.; Che Harun, F. K.; Covington, J. A.; Gardner, J. W.

    2009-05-01

    Our understanding of the human olfactory system, particularly with respect to the phenomenon of nasal chromatography, has led us to develop a new generation of novel odour-sensitive instruments (or electronic noses). This novel instrument is in need of new approaches to data processing so that the information rich signals can be fully exploited; here, we apply a novel time-series based technique for processing such data. The dual-channel, large array artificial olfactory mucosa consists of 3 arrays of 300 sensors each. The sensors are divided into 24 groups, with each group made from a particular type of polymer. The first array is connected to the other two arrays by a pair of retentive columns. One channel is coated with Carbowax 20 M, and the other with OV-1. This configuration partly mimics the nasal chromatography effect, and partly augments it by utilizing not only polar (mucus layer) but also non-polar (artificial) coatings. Such a device presents several challenges to multi-variate data processing: a large, redundant dataset, spatio-temporal output, and small sample space. By applying a novel convolution approach to this problem, it has been demonstrated that these problems can be overcome. The artificial mucosa signals have been classified using a probabilistic neural network and gave an accuracy of 85%. Even better results should be possible through the selection of other sensors with lower correlation.

  7. Optimization of headspace solid-phase microextraction for the analysis of specific flavors in enzyme modified and natural Cheddar cheese using factorial design and response surface methodology.

    Science.gov (United States)

    Januszkiewicz, Julien; Sabik, Hassan; Azarnia, Sorayya; Lee, Byong

    2008-06-27

    A headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC/MS) method was developed using experimental designs to quantify the flavor of commercial Cheddar cheese and enzyme-modified Cheddar cheese (EMCC). Seven target compounds (dimethyl disulfide, hexanal, hexanol, 2-heptanone, ethyl hexanoate, heptanoic acid, delta-decalactone) representative of different chemical families frequently present in Cheddar cheese were selected for this study. Three types of SPME fibres were tested: Carboxen/polydimethylsiloxane (CAR/PDMS), polyacrylate (PA) and Carbowax/divinylbenzene (CW/DVB). NaCl concentration and temperature, as well as extraction time were tested for their effect on the HS-SPME process. Two series of two-level full factorial designs were carried out for each fibre to determine the factors which best support the extraction of target flavors. Therefore, central composite designs (CCDs) were performed and response surface models were derived. Optimal extraction conditions for all selected compounds, including internal standards, were: 50 min at 55 degrees C in 3M NaCl for CAR/PDMS, 64 min at 62 degrees C in 6M NaCl for PA, and 37 min at 67 degrees C in 6M NaCl for CW/DVB. Given its superior sensitivity, CAR/PDMS fibre was selected to evaluate the target analytes in commercial Cheddar cheese and EMCC. With this fibre, calibration curves were linear for all targeted compounds (from 0.5 to 6 microg g(-1)), except for heptanoic acid which only showed a linear response with PA fibres. Detection limits ranged from 0.3 to 1.6 microg g(-1) and quantification limits from 0.8 to 3.6 microg g(-1). The mean repeatability value for all flavor compounds was 8.8%. The method accuracy is satisfactory with recoveries ranging from 97 to 109%. Six of the targeted flavors were detected in commercial Cheddar cheese and EMCC.

  8. Partitioning behavior of aromatic components in jet fuel into diverse membrane-coated fibers.

    Science.gov (United States)

    Baynes, Ronald E; Xia, Xin-Rui; Barlow, Beth M; Riviere, Jim E

    2007-11-01

    Jet fuel components are known to partition into skin and produce occupational irritant contact dermatitis (OICD) and potentially adverse systemic effects. The purpose of this study was to determine how jet fuel components partition (1) from solvent mixtures into diverse membrane-coated fibers (MCFs) and (2) from biological media into MCFs to predict tissue distribution. Three diverse MCFs, polydimethylsiloxane (PDMS, lipophilic), polyacrylate (PA, polarizable), and carbowax (CAR, polar), were selected to simulate the physicochemical properties of skin in vivo. Following an appropriate equilibrium time between the MCF and dosing solutions, the MCF was injected directly into a gas chromatograph/mass spectrometer (GC-MS) to quantify the amount that partitioned into the membrane. Three vehicles (water, 50% ethanol-water, and albumin-containing media solution) were studied for selected jet fuel components. The more hydrophobic the component, the greater was the partitioning into the membranes across all MCF types, especially from water. The presence of ethanol as a surrogate solvent resulted in significantly reduced partitioning into the MCFs with discernible differences across the three fibers based on their chemistries. The presence of a plasma substitute (media) also reduced partitioning into the MCF, with the CAR MCF system being better correlated to the predicted partitioning of aromatic components into skin. This study demonstrated that a single or multiple set of MCF fibers may be used as a surrogate for octanol/water systems and skin to assess partitioning behavior of nine aromatic components frequently formulated with jet fuels. These diverse inert fibers were able to assess solute partitioning from a blood substitute such as media into a membrane possessing physicochemical properties similar to human skin. This information may be incorporated into physiologically based pharmacokinetic (PBPK) models to provide a more accurate assessment of tissue dosimetry of

  9. Optimization of an analytical methodology for the determination of alkyl- and methoxy-phenolic compounds by HS-SPME in biomass smoke

    Energy Technology Data Exchange (ETDEWEB)

    Conde, Francisco J.; Afonso, Ana M.; Gonzalez, Venerando; Ayala, Juan H. [University of La Laguna, Campus de Anchieta, Department of Analytical Chemistry, Nutrition and Food Science, La Laguna (Spain)

    2006-08-15

    A sampling and analysis method for the determination of 21 phenolic compounds in smoke samples from biomass combustion has been developed. The smoke is used to make smoked foods, following an artisanal procedure used in some parts of the Canary Islands. The sampling system consists of a Bravo H air sampler, two impingers, each one containing an aqueous solution of sodium hydroxide 0.1 mol L{sup -1}, followed by a silica gel trap. The variables optimized to reach the best sampling conditions were volume of absorbent solution and sampling flow. Under the optimum conditions, 100 mL of absorbent solution of NaOH 0.10 mol L{sup -1} and 2 L min{sup -1} for the sampling flow, sampling efficiencies are higher than 80%. Analysis of phenolic compounds was carried out by headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Five different fiber coatings were employed in this study. By means of a central composite design, extraction time, salt concentration, and pH of the solution were optimized: 65-{mu}m carbowax-divinylbenzene, extraction time 90 min, concentration in NaCl of 35% (m/v), and pH 2 yielded the highest response. Detection limits of phenol and their alkyl derivatives, guaiacol and eugenol, are between 1.13 and 4.60 ng mL{sup -1}. 3-Methoxyphenol, 2,6-dimethoxyphenol, and vanillin have detection limits considerably higher. Good linearity (R {sup 2}{>=}0.98) was observed for all calibration curves in the established ranges. The reproducibility of the method (RSD, relative standard deviation) was found to oscillate between 7 and 18% (generally close or lower than 10%). (orig.)

  10. Comparative study of the whisky aroma profile based on headspace solid phase microextraction using different fibre coatings.

    Science.gov (United States)

    Câmara, J S; Marques, J C; Perestrelo, R M; Rodrigues, F; Oliveira, L; Andrade, P; Caldeira, M

    2007-05-25

    A dynamic headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to ion trap mass spectrometry (GC-(IT)MS) method was developed and applied for the qualitative determination of the volatile compounds present in commercial whisky samples which alcoholic content was previously adjusted to 13% (v/v). Headspace SPME experimental conditions, such as fibre coating, extraction temperature and extraction time, were optimized in order to improve the extraction process. Five different SPME fibres were used in this study, namely, poly(dimethylsiloxane) (PDMS), poly(acrylate) (PA), Carboxen-poly(dimethylsiloxane) (CAR/PDMS), Carbowax-divinylbenzene (CW/DVB) and Carboxen-poly(dimethylsiloxane)-divinylbenzene (CAR/PDMS/DVB). The best results were obtained using a 75 microm CAR/PDMS fibre during headspace extraction at 40 degrees C with stirring at 750 rpm for 60 min, after saturating the samples with salt. The optimised methodology was then applied to investigate the volatile composition profile of three Scotch whisky samples--Black Label, Ballantines and Highland Clan. Approximately seventy volatile compounds were identified in the these samples, pertaining at several chemical groups, mainly fatty acids ethyl esters, higher alcohols, fatty acids, carbonyl compounds, monoterpenols, C13 norisoprenoids and some volatile phenols. The ethyl esters form an essential group of aroma components in whisky, to which they confer a pleasant aroma, with "fruity" odours. Qualitatively, the isoamyl acetate, with "banana" aroma, was the most interesting. Quantitatively, significant components are ethyl esters of caprilic, capric and lauric acids. The highest concentration of fatty acids, were observed for caprilic and capric acids. From the higher alcohols the fusel oils (3-methylbutan-1-ol and 2.phenyletanol) are the most important ones.

  11. Determination of phenoxy acid herbicides in water by electron-capture and microcoulometric gas chromatography

    Science.gov (United States)

    Goerlitz, D.F.; Lamar, William L.

    1967-01-01

    A sensitive gas chromatographic method using microcoulometric titration and electron-capture detection for the analysis of 2,4-D, silvex, 2,4,5-T, and other phenoxy acid herbicides in water is described. The herbicides are extracted from unfiltered water samples (800-1,000 ml) by use of ethyl ether ; then the herbicides are concentrated and esterilied. To allow the analyst a choice, two esterilication procedures--using either boron trifluoride-methanol or diazomethane--are evaluated. Microcoulometric gas chromatography is specific for the detection of halogenated compounds such as the phenoxy acid herbicides whereas it does not respond to nonhalogenated components. Microcoulometric gas chromatography requires care and patience. It is not convenient for rapid screening of l-liter samples that contain less than 1 microgram of the herbicide. Although electroncapture gas chromatography is less selective and more critically affected by interfering substances, it is, nevertheless, convenient and more sensitive than microcoulometric gas chromatography. Two different liquid phases are used in the gas chromatographic columns--DC-200 silicone in one column and QF-1 silicone in the other. The performance of both columns is improved by the addition of Carbowax 20M. The Gas Chrom Q support is coated with the liquid phases by the 'frontal-analysis' technique. The practical lower limits for measurement of the phenoxy acid herbicides in water primarily depend upon the sample size, interferences present, anal instrumentation used. With l-liter samples of water, the practical lower limits of measurement are 10 ppt (parts per trillion) for 2,4-D and 2 ppt for silvex and 2,4,5-T when electron-capture detection is used, and approximately 20 ppt for each herbicide when analyzed by microcoulometric-titration gas chromatography. Recoveries of the herbicides immediately after addition to unfiltered water samples averaged 92 percent for 2,4-D, 90 percent for silvex, and 98 percent for 2