Effect of the isotopic composition of the solvent (water) in the absolute turbidity of polietilen-glicols solutions

International Nuclear Information System (INIS)

Molinari, M.A.; Videla, G.J.

1975-11-01

Variation in the absolute turbidity of solutions of carbowax 20 M (about 17%) and carbowax 4000 (about 39%) were observed when the relation D 2 O/H 2 O was changed from 0 to 100%, for incident wavelength of 546 and 436 nm. (author) [es

EFFECT OF EMBEDDING METHODS VERSUS FIXATIVE TYPE ON KARYOMETRIC MEASURES

NARCIS (Netherlands)

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

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

Microextracción en fase sólida de compuestos volátiles en albahaca (Ocimum basilicum L. Microextracción en fase sólida de compuestos volátiles en albahaca (Ocimum basilicum L.

Directory of Open Access Journals (Sweden)

Isaac Andrade-González

2012-02-01

Full Text Available Volatile compounds of basil (Ocimum basilicum L. were extracted with solid phase microextraction(SPME and analyzed with gas chromatography-mass spectrometry (GC-MS. TwoSPME fiber coatings, Polydimethylsiloxane/Divinylbenzene (PDMS/DVB, 65 μm and Carbowax/Divinylbenzene (CW/DVB, 65 μm were evaluated in order to compare the extraction ofcomponents. Among the 25 volatile compounds detected were phenylpropanoids, monoterpenes,sesquiterpenes, esters, and aldehydes. There were significant (P Los compuestos volátiles de la albahaca (Ocimum basilicum L. fueron extraídos mediante la microextracción en fase sólida (SPME y analizados con cromatografía de gases-espectrometría de masas (GC-MS. Se evaluaron dos fibras, Polidimetilsiloxano/Divinilbenceno (PDMS/DVB, 65 μm y Carbowax/Divinilbenceno (CW/DVB, 65 μm, para comparar la extracción de componentes. Entre los 25 compuestos volátiles recuperados en la albahaca, se identificaron fenilpropanoides, monoterpenos, sesquiterpenos, ésteres, y aldehídos. Hubieron diferencias significativas (P Cuantitativamente, el componente más importante fue el cinamato de metilo, seguido por el linalol.

Determination of parathion in biological fluids by means of direct Solid Phase Microextraction.

OpenAIRE

Gallardo, Eugenia; Barroso, Mário; Margalho, C.; Cruz, Angelines; Vieira, Duarte Nuno; López-Rivadulla, Manuel

2010-01-01

A new and simple procedure for the determination of parathion in human whole blood and urine using direct immersion (DI) solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) is presented. This technique was developed using only 100 ìL of sample, and ethion was used as internal standard (IS). A 65-ìm Carbowax/divinylbenzene (CW/DVB) SPME fibre was selected for sampling, and the main parameters affecting the SPME process such as extraction ...

Synthesis of Hydroxy-Terminated Dinitropropyl Acrylate Polymers and Improved Characterization of Hydroxy-Terminated Prepolymers

Science.gov (United States)

1983-03-01

CH CH OH P."" 2 2 2 " 2" 2 I2",’C-H CN CN B-2000 Poly-(1,2-butylene)- glycol from DOW Chemical Carbowax Polyethylene glycol from Union Carbide CH...Carbonate GPC Gel Permeation Chromatography HEDS Hydroxyethyl Disulfide HPLC High Pressure Liquid Chromatography NMIM N-methyl imidazole NPGA Neopentyl ...PEG Polyethylene glycol PPG Polypropylene glycol from Wyandotte PY Pyridine R-45M Hydroxy-terminated polybutadeine from ARCO Teracol Poly

Determination of dibutylbutylphosphonate in the presence of tributylphosphate by gas liquid chromatography

International Nuclear Information System (INIS)

Johnson, S.J.

1976-05-01

A gas chromatographic determination of dibutylbutyl-phosphonate in the presence of tributylphosphate was developed. The separation was done on a 183 cm by 3 mm stainless steel column packed with 10 percent Carbowax 20M--TPA on 80/100 mesh Chromosorb W AW and detected by flame ionization. A nitrogen carrier gas flow of 40 cm 3 /min and an oven temperature of 180 0 C produced optimum resolution and column efficiency. The use of temperature programming reduced retention times and thus analysis time. An internal standard of 10 percent v/v n-tridecane was added to all samples and standards

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

International Nuclear Information System (INIS)

Grossmannova, Hana; Ciganek, Miroslav; Krcma, Frantisek

2007-01-01

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 C x H y 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 C x H y 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

Determination of microquantities of methanol and ethanol in toluene by gas chromatography

International Nuclear Information System (INIS)

Perez, M. M.

1970-01-01

A study is made of the detection of methanol and ethanol in toluene by means of gas chromatography, using Porapak Q columns, 1 m long at 189 degree centigree, employing a flame ionization detector, with propanol as an internal standard. The variation od the detector absolute and relative response was found to be linear within the range of concentration studied, that is, from 5 to 1000 ppm. The limit of sensitivity for the detection of ethanol in a column of 2% Ucon, over Chromosorob G deactivated with 0,1% Carbowax 400, was 20 ppm, which was four times higher than the limit of sensitivity of the Porapak Q column. Also in this case, the absolute and relative response of the detector was linear. (Author) 3 refs

Determination of microquantities of methanol and ethanol in toluene by gas chromatography; Determinacion de microcantidades de metanol y de etanol en tolueno por cromatogrfia de gases

Energy Technology Data Exchange (ETDEWEB)

Perez, M M

1970-07-01

A study is made of the detection of methanol and ethanol in toluene by means of gas chromatography, using Porapak Q columns, 1 m long at 189 degree centigree, employing a flame ionization detector, with propanol as an internal standard. The variation od the detector absolute and relative response was found to be linear within the range of concentration studied, that is, from 5 to 1000 ppm. The limit of sensitivity for the detection of ethanol in a column of 2% Ucon, over Chromosorob G deactivated with 0,1% Carbowax 400, was 20 ppm, which was four times higher than the limit of sensitivity of the Porapak Q column. Also in this case, the absolute and relative response of the detector was linear. (Author) 3 refs.

Gas chromatographic determination of calcium propionate added as preservative to bread.

Science.gov (United States)

Lamkin, W M; Unruh, N C; Pomeranz, Y

1987-01-01

A simple and rapid gas chromatographic procedure was developed for determining low concentrations of propionate added as a preservative to bread. A bread sample to be analyzed was ground in a meat grinder with a 3 mm hole plate and finely divided by rubbing through a No. 8 sieve. The propionate was then extracted into 0.050M formic acid in a blender at low speed for 5 min, and an aliquot of a filtrate was analyzed directly by gas chromatography. Chromatographic separation was accomplished on a Carbopack C column coated with 0.3% (w/w) Carbowax 20M and 0.1% (w/w) phosphoric acid. Less than 0.2 ppm propionic acid could be detected in the aqueous extract. Over the range of 0.03-0.23% calcium propionate, average relative error was -1.20% with an average coefficient of variation of 2.02%.

A Headspace Solid Phase Microextraction (HS-SPME method for the chromatographic determination of alkylpyrazines in cocoa samples

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Pini Gláucia F.

2004-01-01

Full Text Available A Headspace Solid Phase Microextraction (HS-SPME procedure for isolation and determination of alkylpyrazines in cocoa liquor, using Gas Chromatography with Flame Ionization Detection (GC-FID for the separation and detection of the analytes, is presented here. The HS-SPME operational conditions were optimized using extractions of samples spiked with known amounts of alkylpyrazines typically found on cocoa products. The maximum extraction efficiency was obtained using SPME fibers coated with 65 µm Carbowax/divinylbenzene. Additionally, the best results were achieved with extraction temperature of 60 ºC, 15 min of sample/headspace equilibration time and 45 min extraction time. It was also observed that suspending the samples in saturated aqueous NaCl solution during extractions resulted in a significant increment on the peak areas. This procedure was found to be effective to determine the so-called pyrazinic ratios (quotient between peak areas of alkylpyrazines, which are useful as quality parameters for cocoa liquor.

Determination of diphenylether herbicides in water samples by solid-phase microextraction coupled to liquid chromatography.

Science.gov (United States)

Sheu, Hong-Li; Sung, Yu-Hsiang; Melwanki, Mahaveer B; Huang, Shang-Da

2006-11-01

Solid-phase microextraction (SPME) coupled to LC for the analysis of five diphenylether herbicides (aclonifen, bifenox, fluoroglycofen-ethyl, oxyfluorfen, and lactofen) is described. Various parameters of extraction of analytes onto the fiber (such as type of fiber, extraction time and temperature, pH, impact of salt and organic solute) and desorption from the fiber in the desorption chamber prior to separation (such as type and composition of desorption solvent, desorption mode, soaking time, and flush-out time) were studied and optimized. Four commercially available SPME fibers were studied. PDMS/divinylbenzene (PDMS/DVB, 60 microm) and carbowax/ templated resin (CW/TPR, 50 microm) fibers were selected due to better extraction efficiencies. Repeatability (RSD, 0.994), and detection limit (0.33-1.74 and 0.22-1.94 ng/mL, respectively, for PDMS/DVB and CW/TPR) were investigated. Relative recovery (81-104% for PDMS/DVB and 83-100% for CW/TPR fiber) values have also been calculated. The developed method was successfully applied to the analysis of river water and water collected from a vegetable garden.

Modified HS-SPME for determination of quantitative relations between low-molecular oxygen compounds in various matrices.

Science.gov (United States)

Dawidowicz, Andrzej L; Szewczyk, Joanna; Dybowski, Michal P

2016-09-07

Similar quantitative relations between individual constituents of the liquid sample established by its direct injection can be obtained applying Polydimethylsiloxane (PDMS) fiber in the headspace solid phase microextraction (HS-SPME) system containing the examined sample suspended in methyl silica oil. This paper proves that the analogous system composed of sample suspension/emulsion in polyethylene glycol (PEG) and Carbowax fiber allows to get similar quantitative relations between components of the mixture as those established by its direct analysis, but only for polar constituents. It is demonstrated for essential oil (EO) components of savory, sage, mint and thyme, and of artificial liquid mixture of polar constituents. The observed differences in quantitative relations between polar constituents estimated by both applied procedures are insignificant (Fexp < Fcrit). The presented results indicates that wider applicability of the system composed of a sample suspended in the oil of the same physicochemical character as that of used SPME fiber coating strongly depends on the character of interactions between analytes-suspending liquid and analytes-fiber coating. Copyright © 2016 Elsevier B.V. All rights reserved.

Oxygen-to-metal ratio control during fabrication of mixed oxide fast breeder reactor fuel pellets

International Nuclear Information System (INIS)

Rasmussen, D.E.; Benecke, M.W.; Jentzen, W.R.; McCord, R.B.

1979-05-01

Oxygen-to-metal ratio (O/M) of mixed oxide fuel pellets can be controlled during fabrication by proper selection of binder (type and content) and sintering conditions. Sintering condition adjustments involved the passing of Ar--8% H 2 sintering gas across a cryostat ice bath controlled to temperatures ranging from -5 to -60 0 C to control as-sintered pellet O/M ratio. As-sintered fuel pellet O/M decreased with increasing Sterotex binder and PuO 2 concentrations, increasing sintering temperature, and decreasing sintering gas dew point. Approximate relationships between Sterotex binder level and O/M were established for PuO 2 --UO 2 and PuO 2 --ThO 2 fuels. O/M was relatively insensitive to Carbowax binder concentration. Several methods of increasing O/M using post-sintering pellet heat treatments were demonstrated, with the most reliable being a two-step process of first raising the O/M to 2.00 (stoichiometric) at 650 0 C in Ar--8% H 2 bubbled through H 2 O, followed by hydrogen reduction to specification O/M in oxygen-gettered Ar-8% H 2 at temperatures ranging from 1200 to 1690 0 C

Application of HS-SPME and GC-MS to characterization of volatile compounds emitted from Osmanthus flowers.

Science.gov (United States)

Deng, Chunhui; Song, Guoxin; Hu, Yaoming

2004-12-01

Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was developed for characterization of volatile compounds emitted from two varieties Osmanthus flowers of O. fragrans var. latifolius and O. fragrans var. thunbergii. The SPME parameters were studied, the optimum conditions of a 65 microm carbowax/divinylbenzene (CW/DVB), extraction temperature of 22 degrees C and extraction time of 10 min were obtained and applied to extraction of the volatile emissions. Fourteen compounds released from both varieties of Osmanthus flowers were separated and identified by GC-MS, which mainly included alpha-linalool, beta-linalool, trans-linalool oxide, cis-linalool oxide, alpha-lonone, beta-lonone, capraldehyde and decalactone. By comparing their peak areas, we found that the sums of the fourteen compounds from the two Osmanthus flowers were very close, while the relative contents of individual volatile compounds in the two emissions were very different. The relative content of alpha-linalool and beta-linalool in O. fragrans var. latifolius were 39.46% and 0.51%, while in O. fragrans var. thunbergii were 9.53% and 27.71%. Due to their different relative contents, the two varieties of flower have different fragrances.

Effect of thickener agents on dental enamel microhardness submitted to at-home bleaching Efeito de agentes espessantes na microdureza do esmalte submetido ao clareamento dental caseiro

Directory of Open Access Journals (Sweden)

José Augusto Rodrigues

2007-06-01

Full Text Available Dental bleaching occurs due to an oxidation reaction between the bleaching agents and the macromolecules of pigments in the teeth. This reaction is unspecific and the peroxides can also affect the dental matrix causing mineral loss. On the other hand, recent studies have suggested that the thickener agent carbopol can also cause mineral loss. Thus, the objective of this study was to evaluate in vitro the effect of at-home dental bleaching on dental enamel microhardness after the use of bleaching agents with and without carbopol as a thickener agent. Bovine dental slabs with 3 x 3 x 3 mm were obtained, sequentially polished, and randomly divided into 4 groups according to the experimental treatment: G1: 2% carbopol; G2: 10% carbamide peroxide with carbopol; G3: carbowax; G4: 10% carbamide peroxide with poloxamer. Bleaching was performed daily for 4 weeks, immersed in artificial saliva. Enamel microhardness values were obtained before the treatment (T0 and 7 (T1, 14 (T2, 21 (T3, 28 (T4, and 42 (T5 days after the beginning of the treatment. ANOVA and Tukey's test revealed statistically significant differences only for the factor Time (F = 5.48; p O clareamento dental ocorre devido a uma reação de oxidação entre o agente clareador e as macromoléculas de pigmentos presentes nos dentes. Esta reação é inespecífica e o peróxido pode agir na matriz dental causando perdas de mineral. Por outro lado, estudos recentes sugerem que o agente espessante carbopol também pode causar perda mineral. Assim, o objetivo deste trabalho foi avaliar in vitro o efeito do clareamento caseiro sobre a microdureza do esmalte após o uso de agentes clareadores com e sem carbopol como espessante. Fragmentos de esmalte bovino de 3 x 3 x 3 mm foram obtidos, polidos seqüencialmente e aleatoriamente divididos em 4 grupos de acordo com o tratamento experimental: G1: carbopol a 2%; G2: peróxido de carbamida a 10% com carbopol; G3: carbowax; G4: peróxido de carbamida a

Variation in composition and yield of foliage oil of eucalyptus polybractea

International Nuclear Information System (INIS)

Iqbal, Z.; Akhtar, M.; Qureshi, T.M.; Ahhter, J.; Ahmad, R.

2011-01-01

Eucalyptus polybractea (blue mallee) is the essential oil rich species used in the commercial production of pharmaceutical-grade Eucalyptus oil in Australia. This species was grown at Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan during 2004-08 to investigate the quantity and quality of its foliage oil. The oils were extracted by hydro-distillation method, from the leaves of four year aged ten E. polybractea plants. The data showed a significant intra-species variation in their oil contents (29.3 to 41.8 mg g-1 fresh weight of leaves). Out of ten plants eight contained oil >30 mg g/sup -1/ fresh weight of leaves. The components of the extracted oils varied from 12-26 as detected by GC/FID on Carbowax 20 M packed glass column. Among all the oil components, 1, 8-cineole was the major compound (91.7-94.2 %), while the other identified compounds were alpha-pinene (0-1.2 %), beta-pinene (0.4-2.3 %), limonene (0.2-1.3 %), p-cymene (1.23-2.75 %), and terpinene-4-ol (0.6-0.92 %). The extracted oils from all the Eucalyptus polybractea plants contained high amount of 1, 8-cineole (>90 %), therefore, classified as species of high quality medicinal oil. (author)

Direct determination of anabolic steroids in pig urine by a new SPME-GC-MS method.

Science.gov (United States)

Zhang, Zhuomin; Duan, Hongbin; Zhang, Lan; Chen, Xi; Liu, Wei; Chen, Guonan

2009-05-15

A new solid phase microextraction (SPME) method coupled with gas chromatography-mass spectrometry (GC-MS) was developed for rapid determination of four anabolic steroids such as 3alpha-hydroxy-5alpha-androstane-17-one (HA), dihydrotestosterone (DHT), androstenedione (AD) and methyltestosterone (MT) in pig urine. SPME was used to extract the four anabolic compounds directly without derivatization. The optimum SPME sampling conditions were based on the home-made carbowax-divinylbenzene (CW-DVB) fiber coating during extraction at 40 degrees C for 50 min with 0.18 g/mL NaCl solution and 750 rpm stirring speed. The linear ranges of the proposed method were in the range of 8-640 pg/mL for HA and DHT and 16-510 pg/mL for AD and MT, respectively. The detection limits (S/N=3) were from 2 to 8 pg/mL for the four anabolic steroids. This SPME method provided very high enrichment factors for the four anabolic steroids, which were 1063-fold and 965-fold for HA and DHT at the concentration of 8 pg/mL and 207-fold and 451-fold for AD and MT at the concentration of 16 pg/mL, respectively. The recoveries ranged from 71.3 to 121%, and the RSDs were lower than 12.9%. The method was sensitive and reliable for determination of trace anabolic steroids in biological samples.

Solid-phase microextraction for gas chromatographic/mass spectrometric analysis of dimethoate in human biological samples.

Science.gov (United States)

Gallardo, E; Barroso, M; Margalho, C; Cruz, A; Vieira, D N; López-Rivadulla, M

2006-01-01

A new, simple and rapid procedure for the determination of dimethoate in urine and blood samples was developed using direct immersion solid-phase microextraction and gas chromatography/mass spectrometry. This technique required only 0.1 mL of sample, and ethion was used as internal standard. Two types of coated fibre were compared (100 microm polydimethylsiloxane, and 65 microm Carbowax/divinylbenzene). Other parameters, such as extraction temperature, adsorption and desorption time, salt addition, agitation and pH, were optimized to enhance the sensitivity of the method. Limits of detection (LODs) and quantitation (LOQs) were 50 and 100 ng/mL for urine and 200 and 500 ng/mL for blood, respectively. The method was found to be linear between the LOQ and 40 microg/mL for urine, and between the LOQ and 50 microg/mL for blood, with correlation coefficients ranging from 0.9923-0.9996. Precision (intra- and interday) and accuracy were in conformity with the criteria normally accepted in bioanalytical method validation. The mean absolute recoveries of dimethoate were 1.24 and 0.50% for urine and blood, respectively. Because of its simplicity and the fact that small volumes of sample are used, the described method can be successfully used in the diagnosis of poisoning by this pesticide, namely in those situations where the sample volume is limited, as frequently occurs in forensic toxicology. Copyright 2006 John Wiley & Sons, Ltd.

Novel capsule phase microextraction in combination with liquid chromatography-tandem mass spectrometry for determining personal care products in environmental water.

Science.gov (United States)

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

2018-05-01

A novel sample preparation technique named capsule phase microextraction (CPME) is presented here. The technique utilizes a miniaturized microextraction capsule (MEC) as the extraction medium. The MEC consists of two conjoined porous tubular polypropylene membranes, one of which encapsulates the sorbent through sol-gel technology, while the other encapsulates a magnetic metal rod. As such, MEC integrates both the extraction and stirring mechanisms into a single device. The aim of this article is to demonstrate the application potential of CPME as sample preparation technique for the extraction of a group of personal care products (PCPs) from water matrices. Among the different sol-gel sorbent materials (UCON ® , poly(caprolactone-dimethylsiloxane-caprolactone) (PCAP-DMS-CAP) and Carbowax 20M (CW-20M)) evaluated, CW-20M MEC demonstrated the best extraction performance for the selected PCPs. The extraction conditions for sol-gel CW-20M MEC were optimized, including sample pH, stirring speed, addition of salt, extraction time, sample volume, liquid desorption solvent, and time. Under the optimal conditions, sol-gel CW-20M MEC provided recoveries, ranging between 47 and 90% for all analytes, except for ethylparaben, which showed a recovery of 26%. The method based on CPME with sol-gel CW-20M followed by liquid chromatography-tandem mass spectrometry was developed and validated for the extraction of PCPs from river water and effluent wastewater samples. When analyzing different environmental samples, some analytes such as 2,4-dihydroxybenzophenone, 2,2-dihydroxy-4-4 methoxybenzophenone and 3-benzophenone were found at low ng L -1 .