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Sample records for on-line bead-injection preconcentration

  1. On-line cation-exchange preconcentration and capillary electrophoresis coupled by tee joint interface.

    PubMed

    Zhang, Zhao-Xiang; He, You-Zhao

    2005-02-25

    An on-line preconcentration method based on ion exchange solid phase extraction was developed for the determination of cationic analytes in capillary electrophoresis (CE). The preconcentration-separation system consisted of a preconcentration capillary bonded with carboxyl cation-exchange stationary phase, a separation capillary for zone electrophoresis and a tee joint interface of the capillaries. Two capillaries were connected closely inside a 0.3 mm i.d. polytetrafluoroethylene tube with a side opening and fixed together by the interface. The preparations of the preconcentration capillaries and interface were described in detail in this paper. The on-line preconcentration and separation procedure of the analysis system included washing and conditioning the capillaries, loading analytes, filling with buffer solution, eluting analytes and separating by capillary zone electrophoresis (CZE). Several analysis parameters, including sample loading flow rate and time, eluting solution and volume, inner diameter and length of preconcentration capillary etc., were investigated. The proposed method enhanced the detection sensitivity of CE-UV about 5000 times for propranolol and metoprolol compared with normally electrokinetic injection. The detection limits of propranolol and metoprolol were 0.02 and 0.1 microg/L with the proposed method respectively, whereas those were 0.1 and 0.5 mg/L with conventional electrokinetic injection. The experiment results demonstrate that the proposed technique can increase the preconcentration factor evidently.

  2. On-line sample preconcentration by sweeping with dodecyltrimethylammonium bromide in capillary zone electrophoresis

    PubMed Central

    Gong, Maojun; Wehmeyer, Kenneth R.; Limbach, Patrick A.; Heineman, William R.

    2008-01-01

    On-line sample preconcentration of oligonucleotides with a new sweeping carrier was developed by using dodecyltrimethylammonium bromide (DTAB) below the critical micelle concentration (CMC). The sweeping results with DTAB below and above the CMC were compared. The use of DTAB below the CMC benefits the preconcentration of the oligonucleotides, while the use of DTAB above the CMC is good for hydrophobic small molecules. The factors affecting the sweeping results were optimized and this method was evaluated by constructing calibration curves for thrombin aptamers. The sweeping scheme produced a 112-fold sensitivity enhancement for the oligonucleotides relative to that run in a running buffer without DTAB. The sweeping method developed here can be a good reinforcement of the preconcentration scheme by sweeping when less-hydrophobic analytes or large negatively-charged molecules need to be preconcentrated. PMID:16808920

  3. On-line flow injection-cloud point preconcentration of polycyclic aromatic hydrocarbons coupled with high-performance liquid chromatography.

    PubMed

    Li, Cheuk Fai; Wong, Jonathan W C; Huie, Carmen W; Choi, Martin M F

    2008-12-19

    Cloud point methodology has been used to develop a novel preconcentration and an analytical method for polycyclic aromatic hydrocarbons (PAHs) in soil sample. The nonionic surfactant Tergitol 15-S-7 was successfully used as the surfactant-mediated extractant in both ultrasonic and microwave-assisted extractions. Over 90% of recoveries for various PAHs in soil were obtained under the optimal experimental conditions. The extracts were then preconcentrated and analyzed by our proposed on-line coupling method "flow injection-cloud point preconcentration-high-performance liquid chromatography" (FI-CPP-HPLC) equipped with a fluorescence detector and an excitation/emission wavelength program. The preconcentration system and optimal working conditions were established. The limit of detection of the FI-CPE-HPLC system ranges from 0.101 to 0.456 microg/L for the selected PAHs, i.e., phenanthrene, pyrene, chrysene, benzo[k]fluoranthene and benzo[a]pyrene. Our proposed technique provides a reliable, simple and automatic analytical method for the determination of PAHs in environmental soil samples.

  4. Analysis of acrylamide in food products by microchip electrophoresis with on-line multiple-preconcentration techniques.

    PubMed

    Wu, Minglei; Chen, Wujuan; Wang, Guan; He, Pingang; Wang, Qingjiang

    2016-10-15

    In this paper, a microchip electrophoresis method based on on-line multiple-preconcentration techniques combining field-amplified sample stacking and reversed-field stacking was developed for highly efficient analysis of acrylamide in food products. The related mechanism as well as important parameters governing separation and preconcentration have been investigated in order to obtain maximum resolution and sensitivity. The best separation was achieved using a 100mM borate solution at pH 9.3 as running buffer, and a sensitivity enhancement factor of 432 was obtained using this concentration method under optimal conditions. The detection limit of acrylamide was 1ng/mL, which was comparable to those previously obtained using CE methods with on-line preconcentration techniques and was 41-700 times lower than those previously reported CE methods without concentration process. The proposed method also gave satisfactory and reliable results in the analysis of acrylamide in potato chips and French fries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Single-step enantioselective amino acid flux analysis by capillary electrophoresis using on-line sample preconcentration with chemical derivatization.

    PubMed

    Ptolemy, Adam S; Tran, Lara; Britz-McKibbin, Philip

    2006-07-15

    Capillary electrophoresis (CE) represents a versatile platform for integrating sample pretreatment with chemical analysis because of its ability to tune analyte electromigration and band dispersion properties in discontinuous electrolyte systems. In this article, a single-step method that combines on-line sample preconcentration with in-capillary chemical derivatization is developed for rapid, sensitive, and enantioselective analysis of micromolar levels of amino acids that lack intrinsic chromophores by CE with UV detection. Time-resolved electrophoretic studies revealed two distinct stages of amino acid band narrowing within the original long sample injection plug occurring both prior to and after in-capillary labeling via zone passing by ortho-phthalaldehyde/N-acetyl l-cysteine (OPA/NAC). This technique enabled direct analysis of d-amino acids in a 95% enantiomeric excess mixture with sub-micromolar detection limits and minimal sample handling, where the capillary functions as a preconcentrator, microreactor, and chiral selector. On-line sample preconcentration with chemical derivatization CE (SPCD-CE) was applied to study the enantioselective amino acid flux in Escherichia coli bacteria cultures, which demonstrated a unique l-Ala efflux into the extracellular medium. New strategies for high-throughput analyses of low-abundance metabolites are important for understanding fundamental physiological processes in bacteria required for screening the efficacy of new classes of antibiotics as well as altered metabolism in genetically modified mutant strains.

  6. New advances in on-line sample preconcentration by capillary electrophoresis using dynamic pH junction.

    PubMed

    Ptolemy, Adam S; Britz-McKibbin, Philip

    2008-12-01

    The small injection volumes and narrow dimensions characteristic of microseparation techniques place constraints on concentration sensitivity that is required for trace chemical analyses. On-line sample preconcentration techniques using dynamic pH junction and its variants have emerged as simple yet effective strategies for enhancing concentration sensitivity of weakly ionic species by capillary electrophoresis (CE). Dynamic pH junction offers a convenient format for electrokinetic focusing of dilute sample plugs directly in-capillary for improved detection without off-line sample pretreatment. In this report, we highlight new advances in dynamic pH junction which have been reported to enhance method performance while discussing challenges for future research.

  7. On-line Determination of Zinc in Water and Biological Samples after Its Preconcentration onto Zincon Anchored Polyurethane Foam.

    PubMed

    Azeem, Sami M Abdel; Hanafi, Hassan A; El-Shahat, M F

    2015-01-01

    A fast and sensitive on-line procedure for the determination of zinc in water and biological samples was developed. Zinc was preconcentrated in a mini-column packed with polyurethane foam (PUF) chemically modified with zincon via -N=N- bonding. The optimal conditions for preconcentration were pH 8.5 and sample flow rate of 4.0 mL min(-1). Quantitative desorption of Zn(II) was obtained by 0.1 mol L(-1) hydrochloric acid and subsequent spectrophotmetric determination using 4-(2-pyridylazo)-resorcinol at 498 nm. The obtained detection limit was found to be 3.0 ng mL(-1), precision (RSD) was 4.8 and 6.7% at 20 and 110 ng mL(-1), respectively, for 60 s preconcentration time and enrichment factor was 31. The linearity range was from 10 to 120 ng mL(-1) and maximum sample throughput was 20 h(-1). Finally, the method was successfully applied to the determination of zinc in tap water, Nile River water and human urine samples with RSD in the range of 1.1 - 8.3%.

  8. On-line preconcentration and speciation of arsenic by flow injection hydride generation atomic absorption spectrophotometry.

    PubMed

    Narcise, Cristine Ingrid S; Coo, Lilibeth Dlc; Del Mundo, Florian R

    2005-12-15

    A flow injection-column preconcentration-hydride generation atomic absorption spectrophotometric (FI-column-HGAAS) method was developed for determining mug/l levels of As(III) and As(V) in water samples, with simultaneous preconcentration and speciation. The speciation scheme involved determining As(V) at neutral pH and As(III+V) at pH 12, with As(III) obtained by difference. The enrichment factor (EF) increased with increase in sample loading volume from 2.5 to 10ml, and for preconcentration using the chloride-form anion exchange column, EFs ranged from 5 to 48 for As(V) and 4 to 24 for As(III+V), with corresponding detection limits of 0.03-0.3 and 0.07-0.3mug/l. Linear concentration range (LCR) also varied with sample loading volume, and for a 5-ml sample was 0.3-5 and 0.2-8mug/l for As(V) and As(III+V), respectively. Sample throughput, which decreased with increase in sample volume, was 8-17 samples/h. For the hydroxide-form column, the EFS for 2.5-10ml samples were 3-23 for As(V) and 2-15 for As(III+V), with corresponding detection limits of 0.07-0.4 and 0.1-0.5mug/l. The LCR for a 5-ml sample was 0.3-10mug/l for As(V) and 0.2-20mug/l for As(III+V). Sample throughput was 10-20 samples/h. The developed method has been effectively applied to tap water and mineral water samples, with recoveries ranging from 90 to 102% for 5-ml samples passed through the two columns.

  9. On-line Sample Preconcentration Using Field-amplified Stacking Injection in Microchip Capillary Electrophoresis

    PubMed Central

    Gong, Maojun; Wehmeyer, Kenneth R.; Limbach, Patrick A.; Arias, Francisco; Heineman, William R.

    2008-01-01

    Previous reports describing sample stacking on microchip capillary electrophoresis (μCE) have regarded the microchip channels as a closed system and treated the bulk flow as in traditional capillary electrophoresis. This work demonstrates that the flows arising from the cross region should be investigated as an open system. It is shown that the pressure-driven flows into or from the branch channels due to bulk velocity mismatch in the main channel should not be neglected but can be used for liquid transportation in the channels. Based on these concepts, a sample preconcentration scheme was developed in a commercially available glass, single-cross chip for μCE. Similar to field-amplified stacking injection in traditional CE, a low conductivity sample buffer plug was introduced into the separation channel immediately before the negatively charged analyte molecules were injected. The detection sensitivity was improved by 94-, 108- and 160-fold for fluorescein-5-isothiocyanate, fluorescein disodium and 5-carboxyfluorescein, respectively, relative to a traditional pinched injection. The calibration curves for fluorescein and 5-carboxyfluorescein demonstrated good linearity in the concentration range (1 to 60 nM) investigated with acceptable reproducibility of migration time and peak height and area ratios (4 to 5% RSD). This preconcentration scheme will be of particular significance to the practical use of μCE in the emerging miniaturized analytical instrumentation. PMID:16737230

  10. On-line preconcentration and determination of lead and cadmium by sequential injection/anodic stripping voltammetry.

    PubMed

    Ninwong, Benjawan; Chuanuwatanakul, Suchada; Chailapakul, Orawon; Dungchai, Wijitar; Motomizu, Shoji

    2012-07-15

    The highly sensitive determination of lead (Pb(II)) and cadmium (Cd(II)) ions, with a limit of detection of 0.01μgL(-1) for Pb(II) and Cd(II), by on-line preconcentration and anodic stripping voltammetry (ASV) controlled by a sequential injection analysis (SIA) system is reported here. The SIA system consisted of a syringe pump, an 8-port selection valve and a 6-port switching valve and was incorporated with a bismuth coated screen-printed carbon nanotube electrode (Bi-SPCNTE). The preconcentration of metal ions was performed by solid phase extraction using an Analig TE-05 chelating resin mini-column on a switching valve. The metal ions collected were then eluted from the resin with 1M hydrochloric acid (HCl), deposited on the electrode surface at -1.3V vs. Ag/AgCl and then measured with ASV. The pH of the sample, eluent volume, flow rate, concentration of the bismuth plating solution and the square-wave voltammetric parameters were optimized. Under the optimum conditions, an enrichment factor of 11.9-fold and 6.6-fold for Pb(II) and Cd(II) ions, respectively, was attained. Detection of Pb(II) and Cd(II) had two different linear ranges (0.5-15μgL(-1) and 15-70μgL(-1)).

  11. Determination of Hg in seawater by inductively coupled plasma mass spectrometry after on-line pre-concentration

    NASA Astrophysics Data System (ADS)

    Seibert, Edson Luiz; Dressler, Valderi Luiz; Pozebon, Dirce; Curtius, Adilson José

    2001-10-01

    A method for the determination of Hg in seawater by inductively coupled plasma mass spectrometry, after an on-line separation and pre-concentration, is described. The matrix separation was accomplished by retention of the Hg complex with the ammonium salt of O, O-diethyl dithiophosphoric acid on C 18 immobilized on silica in a micro-column. Before pre-concentration, the seawater sample was acidified with HNO 3 to 0.14 mol l -1. Methanol was used as the eluent, which was introduced into the conventional pneumatic nebulizer of the instrument. External calibration with aqueous analytical solutions, submitted to the same procedure, was used. An enhancement factor of 16 was obtained, and the limit of detection was 5 ng l -1. The sample consumption was 2.3 ml per determination, and the sampling frequency was 21 h -1. The accuracy was tested by comparison with vapor generation inductively coupled plasma mass spectrometry. The agreement between the Hg concentrations measured by the two methods in the seawater samples was good.

  12. Automated on-line preconcentration of palladium on different sorbents and its determination in environmental samples.

    PubMed

    Sánchez Rojas, Fuensanta; Bosch Ojeda, Catalina; Cano Pavón, José Manuel

    2007-01-01

    The determination of noble metals in environmental samples is of increasing importance. Palladium is often employed as a catalyst in chemical industry and is also used with platinum and rhodium in motor car catalytic converters which might cause environmental pollution problems. Two different sorbents for palladium preconcentration in different samples were investigated: silica gel functionalized with 1,5-bis(di-2-pyridyl)methylene tbiocarbohydrazide (DPTH-gel) and [1,5-Bis(2-pyridyl)-3-sulphophenyI methylene thiocarbonohydrazide (PSTH) immobilised on an anion-exchange resin (Dowex lx8-200)]. The sorbents were tested in a micro-column, placed in the auto-sampler arm, at the flow rate 2.8 mL min(-1). Elution was performed with 4 M HCl and 4 M HNO3, respectively. Satisfactory results were obtained for two sorbents.

  13. A preconcentration procedure for the determination of cadmium in biological material after on-line cloud point extraction.

    PubMed

    Baliza, Patrícia Xavier; Cardoso, Luiz Augusto Martins; Lemos, Valfredo Azevedo

    2012-07-01

    In this paper, a method involving on-line preconcentration with cloud point extraction for the determination of cadmium in biological samples is presented. The procedure is based on the sorption of micelles containing Cd(II) ions and the reagent 4-(5'-bromo-2'-thiazolylazo)orcinol (Br-TAO) in a minicolumn packed with polyester. The surfactant Triton X-114 was used in the formation of micelles. After sorption, the Cd(II) ions were desorbed from the minicolumn with acid eluent and determined by flame atomic absorption spectrometry. Parameters influencing the cloud point extraction were studied. The method showed a detection limit of 0.5 μg l(-1) and an enhancement factor of 27. The accuracy was tested by determination of cadmium in certified reference materials (spinach leaves 1570a and tomato leaves 1573a) from the National Institute of Standards and Technology.

  14. The Trace Analysis of DEET in Water using an On-line Preconcentration Column and Liquid Chromatography with UV Photodiode Array Detection

    EPA Science Inventory

    A method for the detection of trace levels of N,N-diethyl-m-toluamide (DEET) in water is discussed. The method utilizes an on-line preconcentration column in series with high performance liquid chromatography (HPLC) and UV photodiode array detection. DEET, a common insect repel...

  15. Sensitive simultaneous determination of three sulfanilamide artificial sweeters by capillary electrophoresis with on-line preconcentration and contactless conductivity detection.

    PubMed

    Yang, Lirong; Zhou, ShengJi; Xiao, Yuezhou; Tang, Yufeng; Xie, Tianyao

    2015-12-01

    A sensitive method followed by capillary electrophoresis with on-line perconcentration and capacitively coupled contactless conductivity detection (CE-C(4)D) was evaluated as a novel approach for the determination of three sulfanilamide artificial sweeteners (acesulfame-K, sodium saccharin and sodium cyclamate) in beverages. The on-line preconcentration technique, namely field-amplified sample injection, coupled with CE-C(4)D were successfully developed and optimized. The separation was achieved within 10 min under the following conditions: an uncoated fused-silica capillary (45 cm × 50 μm i.d., Leff=40 cm), 20 mmol L(-1) HAc as running buffer, separation voltage of -12 kV, electrokinetic injection of -11 kV × 8 s. The detection limits of acesulfame-K, sodium saccharin and sodium cyclamate were 4.4, 6.7 and 8.8 μg L(-1), respectively. The relative standard deviation varied in the range of 3.0-5.0%. Results of this study show a great potential method for the fast screening of these artificial sweeteners contents in commercial beverages. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. On-line sample preconcentration and separation technique based on transient trapping in microchip micellar electrokinetic chromatography.

    PubMed

    Sueyoshi, Kenji; Kitagawa, Fumihiko; Otsuka, Koji

    2008-02-15

    This paper describes a novel on-line sample preconcentration and separation technique named transient trapping (tr-trapping), which improves the efficiencies of separation and concentration by using a partially injected short micellar plug in microchip electrophoresis. Although a longer separation length often provides a better resolution of complexed or closely migrating analytes, our proposed theoretical model indicated that a trap-and-release mechanism enables a short micellar zone, which was partially injected into the separation channel, to work as an effective concentration and separation field. Application of the tr-trapping technique to microchip micellar electrokinetic chromatography (MCMEKC) was performed on a newly fabricated 5-way-cross microchip by using sodium dodecyl sulfate and rhodamine dyes as test micelle and analytes, respectively. When the injection times of micelle (t(inj),M) and sample solution (t(inj),S) were 1.0 and 2.0 s, respectively, both the preconcentration and separation of the dyes were completely finished within only 3.0 s. At t(inj),S of 8.0 s, a 393-fold improvement of the detectability was achieved in comparison with conventional MCMEKC. The resolution obtained with tr-trapping-MCMEKC was also better than that with conventional MCMEKC in spite of the 160-fold shorter length of the injected micellar zone at t(inj),M of 1.0 s. These results clearly demonstrated that the tr-trapping technique in MCMEKC provides a rapid, high-resolution and detectability analysis even in the short separation channel on the microchips.

  17. Determination of heavy metals by inductively coupled plasma mass spectrometry after on-line separation and preconcentration

    NASA Astrophysics Data System (ADS)

    Dressler, Valderi L.; Pozebon, Dirce; Curtius, Adilson J.

    1998-10-01

    A method for the determination of Cu, As, Se, Cd, In, Hg, Tl, Pb and Bi in waters and in biological materials by inductively coupled plasma mass spectrometry, after an on-line separation, is described. The matrix separation and analyte preconcentration is accomplished by retention of the analytes complexed with the ammonium salt of O,O-diethyl dithiophosphoric acid in a HNO 3 solution on C 18 immobilized on silica in a minicolumn. Methanol, as eluent, is introduced in the conventional pneumatic nebulizer of the instrument. In order to use the best compromise conditions, concerning the ligand and acid concentrations, the analytes were determined in two separate groups. The enrichment factors were in the range from 5 to 61, depending on the analyte. The limits of detection varied from 0.43 ng L -1 for Bi to 33 ng L -1 for Cu. The sample consumption is only 2.3 mL for each group and the sampling frequency is 21 h -1. The accuracy was tested by analysing five certified reference materials: water, riverine water, urine, bovine muscle and bovine liver. The agreement between obtained and certified concentrations was very good, except for As. The relatively small volume of methanol, used as eluent, minimizes the problems produced by the introduction of organic solvent into the plasma.

  18. On-line two-step stacking in capillary zone electrophoresis for the preconcentration of strychnine and brucine.

    PubMed

    Yang, Xiumin; Zhang, Shuaihua; Wang, Juntao; Wang, Chun; Wang, Zhi

    2014-03-03

    An on-line sample preconcentration method by two-step stacking i.e., sweeping and micelle to solvent stacking, in capillary zone electrophoresis (CZE) has been developed for the determination of strychnine and brucine in traditional Chinese herbal medicines. After experimental optimizations, the best separation was achieved by using 75 mM phosphate buffer (pH 2.5) with 30% methanol (v/v). Compared with normal CZE injection, 51- and 38-fold improvement in concentration sensitivity was achieved for strychnine and brucine, respectively. The calibration curve was linear in the range of 0.1-5.0 μg mL(-1) for both strychnine and brucine, with the correlation coefficients of 0.9998 and 0.9997, respectively. The limits of detection (S/N=3) for both alkaloids were 0.01 μg mL(-1). The inter-day (n=8) and intra-day (n=5) reproducibilities expressed as the relative standard deviations for corrected peak area were less than 9.5%. The method was applied to determine strychnine and brucine in two Chinese herbal medicines, with recoveries ranging from 94.2% to 105.4%. The results indicated that the method is simple, rapid, reliable, and can be applied to determine strychnos alkaloids in traditional Chinese herbal medicines. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Determination of scandium in acid mine drainage by ICP-OES with flow injection on-line preconcentration using oxidized multiwalled carbon nanotubes.

    PubMed

    Jerez, Javier; Isaguirre, Andrea C; Bazán, Cristian; Martinez, Luis D; Cerutti, Soledad

    2014-06-01

    An on-line scandium preconcentration and determination system implemented with inductively coupled plasma optical emission spectrometry associated with flow injection was studied. Trace amounts of scandium were preconcentrated by sorption on a minicolumn packed with oxidized multiwalled carbon nanotubes, at pH 1.5. The retained analyte was removed from the minicolumn with 30% (v/v) nitric acid. A total enrichment factor of 225-fold was obtained within a preconcentration time of 300 s (for a 25 mL sample volume). The overall time required for preconcentration and elution of 25 mL of sample was about 6 min; the throughput was about 10 samples per hour. The value of the detection limit was 4 ng L(-1) and the precision for 10 replicate determinations at 100 ng L(-1) Sc level was 5% relative standard deviation, calculated from the peak heights obtained. The calibration graph using the preconcentration system was linear with a correlation coefficient of 0.9996 at levels near the detection limits up to at least 10 mg L(-1). After optimization, the method was successfully applied to the determination of Sc in an acid drainage from an abandoned mine located in the province of San Luis, Argentina.

  20. On-line complexation/cloud point preconcentration for the sensitive determination of dysprosium in urine by flow injection inductively coupled plasma-optical emission spectrometry.

    PubMed

    Ortega, Claudia; Cerutti, Soledad; Olsina, Roberto A; Silva, María F; Martinez, Luis D

    2003-01-01

    An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with ICP-OES was studied. For the preconcentration of dysprosium, a Dy(III)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex was formed on-line at pH 9.22 in the presence of nonionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 30 degrees C in order to promote phase separation, and the surfactant-rich phase was retained in a microcolumn packed with cotton at pH 9.2. The surfactant-rich phase was eluted with 4 mol L(-1) nitric acid at a flow rate of 1.5 mL min(-1), directly in the nebulizer of the plasma. An enhancement factor of 50 was obtained for the preconcentration of 50 mL of sample solution. The detection limit value for the preconcentration of 50 mL of aqueous solution of Dy was 0.03 microg L(-1). The precision for 10 replicate determinations at the 2.0 microg L(-1)Dy level was 2.2% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for dysprosium was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 microg L(-1). The method was successfully applied to the determination of dysprosium in urine.

  1. Determining ultraviolet absorbents in sunscreen products by combining direct injection with micelle collapse on-line preconcentration capillary electrophoresis.

    PubMed

    Hsiao, Wen-Yao; Jiang, Shiuh-Jen; Feng, Chia-Hsien; Wang, Shih-Wei; Chen, Yen-Ling

    2015-02-27

    The on-line preconcentration technique of analyte focusing by micelle collapse-micellar electrokinetic chromatography (AFMC-MEKC) was combined with direct injection without extraction to determine ultraviolet absorbents in sunscreen products. The stacking mechanism is based on the transport, release, and accumulation of analytes bound to micelle carriers that are collapsed into the micelle dilution zone. The following optimized conditions were determined: the running buffer was 10mM Tris buffer (pH 9.5) containing 60mM SDS, 7mM γ-CD and 20% ethanol; the SDS concentration was required to be slightly above the critical micelle concentration (cmc) value (7.4mM) in the sample matrix, which allowed the micelle dilution zone to form when voltage was applied; and finally, the sample was prepared in 100mM Tris buffer (pH 9.0) containing 7.5mM SDS and 20% (v/v) ethanol to provide sufficient resolution and to improve the sensitivity. Samples were injected at 0.5psi for 40s, and the separation voltage was set at 15kV for first 15min and then increased to 23kV to decrease the analysis time. The detection sensitivity for ultraviolet absorbents was enhanced by approximately 41-fold using AFMC-MEKC compared to conventional MEKC. The limit of detection (S/N=3) was 98nM for benzophenone-2 and benzophenone-4. The correlation of the regression curve was greater than 0.995. The relative error and relative standard deviation were lower than 9.94% with high precision and accuracy. The recoveries of nine ultraviolet absorbents in a homemade emulsion were between 95.08% and 104.57%. After optimization and validation, this AFMC-MEKC method combined with direct injection is considered to be established and successfully applicable to commercial sunscreen products.

  2. Thermospray flame furnace-AAS determination of copper after on-line sorbent preconcentration using a system optimized by experimental designs.

    PubMed

    Tarley, César Ricardo Teixeira; Figueiredo, Eduardo da Costa; Matos, Geraldo Domingues

    2005-11-01

    The present paper describes the on-line coupling of a flow-injection system to a new technique, thermospray flame furnace-AAS (TS-FF-AAS), for the preconcentration and determination of copper in water samples. Copper was preconcentrated onto polyurethane foam (PUF) complexed with ammonium O,O-diethyldithiophosphate (DDTP), while elution was performed using 80% (v/v) ethanol. An experimental design for optimizing the copper preconcentration system was established using a full factorial (2(4)) design without replicates for screening and a Doehlert design for optimization, studying four variables: sample pH, ammonium O,O-diethyldithiophosphate (DDTP) concentration, presence of a coil and the sampling flow rate. The results obtained from the full factorial and based on a Pareto chart indicate that only the pH and the DDTP concentration, as well as their interaction, exert influence on the system within a 95% confidence level. The proposed method provided a preconcentration factor of 65 fold, thus notably improving the detectability of TS-FF-AAS. The detection limit was 0.22 microg/dm3 and the precision, expressed as the relative standard deviation (RSD) for eight independent determinations, was 2.7 and 1.1 for copper solutions containing 5 and 30 microg/dm3, respectively. The procedure was successfully applied for copper determination in water samples.

  3. On-line preconcentration and determination of cadmium in honey using knotted reactor coupled to flow injection-flame atomic absorption spectrometry.

    PubMed

    Fernández, Orsi Ricardo; Wuilloud, Rodolfo G; de Wuilloud, Jorgelina C A; Olsina, Roberto A; Martinez, Luis D

    2002-01-01

    An on-line cadmium preconcentration and determination system implemented with flame atomic absorption spectrometry (FAAS) associated with flow injection was studied. Cadmium was retained as Cd-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol Cd-(5-Br-PADAP) complex, pH 9.3. The Cd complex was removed from the knotted reactor (KR) with ethanol. A total enhancement factor of 140 was obtained with respect to FAAS (40 for KR and 3.5 due to the use of ethanol) with preconcentration time of 120 s. The detection limit value for preconcentration of 1 g sample was 0.5 ng/g. The repeatability for 10 replicate determinations at 5.0 ng/g Cd level was 3.5% relative standard deviation, calculated from peak heights obtained. The calibration graph using the preconcentration system for Cd was linear with a correlation coefficient of 0.9990 at levels near the detection limits to at least 2000 ng/g. The method was successfully applied to determination of total Cd in honey samples.

  4. Determination of low cadmium concentrations in wine by on-line preconcentration in a knotted reactor coupled to an inductively coupled plasma optical emission spectrometer with ultrasonic nebulization.

    PubMed

    Lara, R F; Wuilloud, R G; Salonia, J A; Olsina, R A; Martinez, L D

    2001-12-01

    An on-line cadmium preconcentration and determination system implemented with inductively coupled plasma optical emission spectrometry (ICP-OES) associated to flow injection (FI) with ultrasonic nebulization system (USN) was studied. The cadmium was retained as the cadmium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, Cd-(5-Br-PADAP), complex, at pH 9.5. The cadmium complex was removed from the knotted reactor (KR) with 3.0 mol/L nitric acid. A total enhancement factor of 216 was obtained with respect to ICP-OES using pneumatic nebulization (12 for USN and 18 for KR) with a preconcentration time of 60 s. The value of the detection limit for the preconcentration of 5 mL of sample solution was 5 ng/L. The precision for 10 replicate determinations at the 5 microg/L Cd level was 2.9% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for cadmium was linear with a correlation coefficient of 0.9998 at levels near the detection limits up to at least 1,000 microg/L. The method was successfully applied to the determination of cadmium in wine samples.

  5. [Determination of trace and ultra-trace level bromate in water by large volume sample injection with enrichment column for on-line preconcentration coupled with ion chromatography].

    PubMed

    Liu, Jing; He, Qingqing; Yang, Lili; Hu, Enyu; Wang, Meifei

    2015-10-01

    A method for the determination of trace and ultra-trace level bromate in water by ion chromatography with large volume sample injection for on-line preconcentration was established. A high capacity Dionex IonPac AG23 guard column was simply used as the enrichment column instead of the loop for the preconcentration of bromate. High purity KOH solution used as eluent for gradient elution was on-line produced by an eluent generator automatically. The results showed that a good linear relationship of bromate was exhibited in the range of 0.05-51.2 μg/L (r ≥ 0.999 5), and the method detection limit was 0.01 μg/L. Compared with conventional sample injection, the injection volume was up to 5 mL, and the enrichment factor of this method was about 240 times. This method was successfully applied for several real samples of pure water which were purchased in the supermarket, and the recoveries of bromate were between 90%-100% with the RSDs (n = 6) of 2.1%-6.4% at two spiked levels. This method without pretreatment is simple, and of high accuracy and precision. The preconcentration can be achieved by large volume sample injection. It is suitable for the analysis of trace and ultra-trace level bromate.

  6. Separation and on-line preconcentration by stacking and sweeping of charged analytes in the plant by microemulsion electrokinetic chromatography with nonionic surfactants.

    PubMed

    Cao, Jun; Qi, Lian-Wen; Liu, E-Hu; Zhang, Wei-Dong; Li, Ping

    2009-02-20

    A novel on-line technique for stacking and sweeping of long sample plugs with simultaneous determination of charged analytes in the plant (protocatechuic aldehyde, rosmarinic acid, danshensu, salvianolic acid B, and protocatechuic acid) by the nonionic microemulsion electrokinetic chromatography (MEEKC) is presented. The preconcentration efficiency provided about 9-28-fold for stacking and 7-14-fold for sweeping in the enhancements of LOD. The effects of oil phase, Brij-35 and buffer concentrations on stacking and sweeping efficiency were examined in order to optimize the two methods. In nonionic MEEKC, the effect of the type of oil and buffer contents on preconcentration mechanism is often sophisticated. This study had demonstrated that the oil type and buffer content in nonionic microemulsion indeed markedly altered the affinity of microemulsion with analytes. Finally, in comparison to the stacking method, the most apparent disadvantages of the sweeping method were the relatively high limits of detection and poor peak shapes.

  7. Single-step analysis of low abundance phosphoamino acids via on-line sample preconcentration with chemical derivatization by capillary electrophoresis.

    PubMed

    Ptolemy, Adam S; Britz-McKibbin, Philip

    2005-09-01

    New strategies for rapid, sensitive and high-throughput analysis of low abundance metabolites in biological samples are required for future metabolomic research. In this report, a direct method for sub-micromolar analyses of phosphoamino acids was developed using on-line sample preconcentration with 9-fluorenylmethyloxycarbonyl chloride (FMOC) derivatization by capillary electrophoresis (CE) and UV detection. Analyte focusing by dynamic pH junction and FMOC labeling efficiency were influenced by several experimental factors including buffer pH, ionic strength, sample injection length and FMOC concentration. About a 200-fold enhancement in concentration sensitivity was achieved under optimal conditions relative to conventional off-line derivatization, as reflected by a detection limit (S/N approximately 3) of 0.1 microM. In-capillary sample preconcentration with chemical labeling by CE offers a unique single-step analytical platform for high-throughput screening of low abundance metabolites without intrinsic chromophores.

  8. An on-line SPE-HPLC method for effective sample preconcentration and determination of fenoxycarb and cis, trans-permethrin in surface waters.

    PubMed

    Šatínský, Dalibor; Naibrtová, Linda; Fernández-Ramos, Carolina; Solich, Petr

    2015-09-01

    A new on-line SPE-HPLC method using fused-core columns for on-line solid phase extraction and large volume sample injection for increasing the sensitivity of detection was developed for the determination of insecticides fenoxycarb and cis-, trans-permethrin in surface waters. The separation was carried out on fused-core column Phenyl-Hexyl (100×4.6 mm), particle size 2.7 µm with mobile phase acetonitrile:water in gradient mode at flow rate 1.0 mL min(-1), column temperature 45°C. Large volume sample injection (1500 µL) to the extraction dimension using short precolumn Ascentis Express RP C-18 (5×4.6 mm); fused-core particle size 2.7 µm allowed effective sample preconcentration and efficient ballast sample matrix removal. The washing mobile phase consisting of a mixture of acetonitrile:water; 30:70, (v/v) was pumped at flow rate of 0.5 mL min(-1) through the extraction precolumn to the waste. Time of the valve switch for transferring the preconcentrated sample zone from the extraction to the separation column was set at 3rd min. Elution of preconcentrated insecticides from the extraction precolumn and separation on the analytical column was performed in gradient mode. Linear gradient elution started from 40% of acetonitrile at time of valve switch from SPE column (3rd min) to 95% of acetonitrile at 7th min. Synthetic dye sudan I was chosen as an internal standard. UV detection at wavelength 225 nm was used and the method reached the limits of detection (LOD) at ng mL(-1) levels for both insecticides. The method showing on-line sample pretreatment and preconcentration with highly sensitive determination of insecticides was applied for monitoring of fenoxycarb and both permethrin isomers in different surface water samples in Czech Republic. The time of whole analysis including on-line extraction, interferences removal, chromatography separation and system equilibration was less than 8 min. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Screening method for linear alkylbenzene sulfonates in sediments based on water Soxhlet extraction assisted by focused microwaves with on-line preconcentration/derivatization/detection.

    PubMed

    Morales-Muñoz, S; Luque-García, J L; de Castro, Luque

    2004-02-13

    A screening method for linear alkylbenzene sulfonates (LAS) in sediments has been developed. Soxhlet extraction with water assisted by focused microwaves provides recoveries better (>90%) than obtained by conventional Soxhlet extraction (70-80%). Coupling of the extractor with an on-line preconcentration/derivatization/detection manifold through a flow injection (FI) interface allows a fully automated screening approach. A yes/no answer can be obtained in less than 2 h (for the whole analytical process), a short time compared with the at least 24 h of Soxhlet extraction (without final detection). Due to the use of water as leaching agent, the proposed method is environmentally friendly.

  10. Preconcentration and speciation of chromium in drinking water samples by coupling of on-line sorption on activated carbon to ETAAS determination.

    PubMed

    Gil, R A; Cerutti, S; Gásquez, J A; Olsina, R A; Martinez, L D

    2006-02-15

    An on-line flow injection (FI) preconcentration-electrothermal atomic absorption spectrometry (ETAAS) method is developed for trace determination of chromium in drinking water samples by sorption on a conical minicolumn packed with activated carbon (AC) at pH 5.0. The chromium was removed from the minicolumn with 1.0% (v/v) nitric acid. An enrichment factor (EF) of 35-fold for a sample volume of 10ml was obtained. The detection limit (DL) value for the preconcentration method proposed was 3.0ngl(-1). The precision for 10 replicate determinations at the 0.5mugl(-1) Cr level was 4.0% relative standard deviation (R.S.D.), calculate with the peak heights obtained. The calibration graph using the preconcentration system for chromium was linear with a correlation coefficient of 0.9992 at levels near the detection limits up to at least 50mugl(-1). The method was successfully applied to the determination of Cr(III) and Cr(VI) in drinking water samples.

  11. Use of factorial design and Doehlert matrix for multivariate optimisation of an on-line preconcentration system for lead determination by flame atomic absorption spectrometry.

    PubMed

    Ferreira, S L C; dos Santos, W N L; Bezerra, M A; Lemos, V A; Bosque-Sendra, J M

    2003-02-01

    A system for on-line preconcentration and determination of lead by flame atomic absorption spectrometry (FAAS) was proposed. It was based on the sorption of lead(II) ions on a minicolumn of polyurethane foam loaded with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM). The optimisation step was carried out using two-level full factorial and Doehlert designs for the determination of the optimum conditions for lead preconcentration. The proposed procedure allowed the determination of lead with a detection limit of 2.2 microg L(-1), and a precision, calculated as relative standard deviation (RSD), of 2.4 and 6.8 for a lead concentration of 50.0 and 10.0 microg L(-1), respectively. A preconcentration factor of 45 and a sampling frequency of 27 samples per hour were obtained. The recovery achieved for lead determination in the presence of several cations demonstrated that this procedure has enough selectivity for analysis of environmental samples. The validation was carried out by analysis of certified reference material. This procedure was applied to lead determination in natural food.

  12. Cloud point extraction for cobalt preconcentration with on-line phase separation in a knotted reactor followed by ETAAS determination in drinking waters.

    PubMed

    Gil, Raúl A; Gásquez, José A; Olsina, Roberto; Martinez, Luis D; Cerutti, Soledad

    2008-07-30

    A novel method for cobalt preconcentration by cloud point extraction with on-line phase separation in a PTFE knotted reactor and further determination by electrothermal atomic absorption spectrometry (ETAAS) is proposed. The cloud point system was formed in the presence of non-ionic micelles of polyethyleneglycolmono-p-nonylphenylether (PONPE 7.5) and it was retained on the inner walls of a knotted reactor (KR). The surfactant rich-phase was removed from the knotted reactor with 75 microL of methanol acidified with 0.8 mol L(-1) nitric acid, directly into the dosing hole of the L'Vov graphite tube. An enrichment factor of 15 was obtained with a preconcentration time of 60 s, with respect to the direct determination of cobalt by ETAAS in aqueous solutions. The value of the detection limit for the preconcentration of 5 mL of sample solution was 10 ng L(-1). The precision, expressed as the relative standard deviation (R.S.D.), for 10 replicate determinations at 0.5 microg L(-1) Co level was 4.5%. Verification of the accuracy was carried out by analysis of a standard reference material (NIST SRM 1640e "Trace elements in natural water"). The method was successfully applied to the determination of cobalt in drinking water samples.

  13. A novel fiber-packed column for on-line preconcentration and speciation analysis of chromium in drinking water with flame atomic absorption spectrometry.

    PubMed

    Monasterio, Romina P; Altamirano, Jorgelina C; Martínez, Luis D; Wuilloud, Rodolfo G

    2009-02-15

    A novel on-line preconcentration and determination system based on a fiber-packed column was developed for speciation analysis of Cr in drinking water samples prior to its determination by flame atomic absorption spectrometry (FAAS). All variables involved in the development of the preconcentration method including, pH, eluent type, sample and eluent flow rates, interfering effects, etc., were studied in order to achieve the best analytical performance. A preconcentration factor of 32 was obtained for Cr(VI) and Cr(III). The levels of Cr(III) species were calculated by difference of total Cr and Cr(VI) levels. Total Cr was determined after oxidation of Cr(III) to Cr(VI) with hydrogen peroxide. The calibration graph was linear with a correlation coefficient of 0.999 at levels near the detection limit and up to at least 50 microg L(-1). The relative standard deviation (R.S.D.) was 4.3% (C=5 microg L(-1) Cr(VI), n=10, sample volume=25 mL). The limit of detection (LOD) for both Cr(III) and Cr(VI) species was 0.3 microg L(-1). Verification of the accuracy was carried out by the analysis of a standard reference material (NIST SRM 1643e "Trace elements in natural water"). The method was successfully applied to the determination of Cr(III) and Cr(VI) species in drinking water samples.

  14. On-line preconcentration/determination of zinc from water, biological and food samples using synthesized chelating resin and flame atomic absorption spectrometry.

    PubMed

    Yılmaz, Sibel; Tokalıoğlu, Serife; Sahan, Serkan; Ulgen, Ahmet; Sahan, Ahmet; Soykan, Cengiz

    2013-04-01

    An on-line flow injection pre-concentration-flame atomic absorption spectrometry method was developed to determine trace zinc in water (tap, dam, and well water), biological (hair and nail), and liver samples. As a solid phase extractant, a synthesized new chelating resin, poly(2-thiozylmethacrylamide-co-divinylbenzene-co-2-acrylamido-2-methyl-1-propane sulfonic acid) was used. The resin was characterized by Fourier transform infrared spectroscopy, elemental analysis, and surface area by nitrogen sorption. A pre-concentration factor of 40-fold for a sample volume of 12.6 mL was obtained by using the time-based technique. The detection limit for the pre-concentration method was found to be 2.2 μg L(-1). The precision (as RSD,%) for 10 replicate determinations at the 0.04 μg mL(-1) Zn concentration was 1.2%. The calibration graph using the pre-concentration system for zinc was linear with a correlation coefficient of 0.998 in the concentration range from 0.005 to 0.05 μg mL(-1). The applicability and accuracy of the developed method were estimated by the analysis spiked water, biological, liver samples (83-105%), and also certified reference material TMDA-70 (fortified lake water) and SPS-WW1 Batch 111-Wastewater. The results were in agreement with the certified values.

  15. On-line flow injection molecularly imprinted solid phase extraction for the preconcentration and determination of 1-hydroxypyrene in urine samples.

    PubMed

    Serrano, Montserrat; Bartolomé, Mónica; Bravo, Juan Carlos; Paniagua, Gema; Gañan, Judith; Gallego-Picó, Alejandrina; Garcinuño, Rosa María

    2017-05-01

    New analytical strategies tend to automation of sample pre-treatment and flow analysis techniques provided a number of enhanced analytical methods allowing high throughput. Flow techniques are usually faster, more robust and more flexible than their batch equivalents. In addition, flow methods use less sample and reagent amounts and reduce analytical costs and waste. A flow injection solid-phase extraction pre-concentration system using a molecularly imprinted polymer (MIP) packed micro-column was developed for the determination of 1-hydroxypyrene in human urine with fluorescence detection. The pre-concentration of 1-hydroxypyrene on the MIP was carried out based on the specific retention of analyte by on-line introducing the sample into the micro-column system. Methanol and dichloromethane mixture was used to elute the retained analyte for fluorometric analysis. Important influencing factors were studied in detail, in batch and in flow (MISPE procedure optimisation, sample and eluent volumes, flow rate, dimensions of MIP micro-column and amounts of packing material, etc). To the best of our knowledge, this is the first on-line flow injection molecularly imprinted solid phase extraction for the pre-concentration and determination of hydroxylate PAH metabolite in urine samples. The optimised method was successfully applied to the determination of 1-Hydroxypyrene in spiked urine samples, with recoveries in the range of 74-85% and RSD<4.6%. Under optimum experimental conditions, the linearity concentration range used was 10-400μgL(-1), R(2)>0.996. We obtained limit of detection and quantification of 3.1μgL(-1) and 10.5μgL(-1), respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. On-line preconcentration and recovery of palladium from waters using polyaniline (PANI) loaded in mini-column and determination by ICP-MS; elimination of spectral interferences.

    PubMed

    Krishna, M V Balarama; Ranjit, Manjusha; Chandrasekaran, K; Venkateswarlu, G; Karunasagar, D

    2009-10-15

    The applicability of polyaniline (PANI) for the on-line preconcentration and recovery of palladium from various water samples has been investigated. Batch experiments were performed to optimize conditions such as pH and contact time to achieve quantitative separation of Pd spiked at high (microg ml(-1)) and low levels (ng ml(-1)). During all the steps of the removal process, it was found that Pd was selectively removed by PANI even in the presence of various ions. Quantitative removal of Pd occured in the entire studied pH range (1-12) and the K(d) value was found to be >10(6). Kinetic studies show that a contact time of <4 min was adequate to reach equilibrium. The retained Pd was subsequently eluted with a mixture of HCl and thiourea, optimized using a factorial experimental design approach. ICP-OES was used for the micro-level determinations of Pd whereas ICP-MS was used for the determination of Pd at sub-ppb levels. Breakthrough curve using column experiments demonstrated that PANI has an excellent ability to accumulate up to approximately 120 mg g(-1) of Pd from synthetic sample solutions. A preconcentration factor of about 125 was achieved for Pd when 250 ml of water was passed. PANI columns prepared were used up to 10 times in consecutive retention-elution cycles without appreciable deterioration in their performance. The proposed on-line method also has the ability to remove interfering elements Cu and Y for the determination of Pd in waters by ICP-MS. The reported method has been applied successfully for the determination of Pd in ground water, lake water sea-water and waste water samples. The recoveries were found to be >95% in all cases. These studies indicate that PANI has an excellent ability to preconcentrate Pd from various waters making the method very promising for the determination of Pd.

  17. On-line sample preconcentration with chemical derivatization of bacterial biomarkers by capillary electrophoresis: a dual strategy for integrating sample pretreatment with chemical analysis.

    PubMed

    Ptolemy, Adam S; Le Bihan, Marianne; Britz-McKibbin, Philip

    2005-11-01

    Simple, selective yet sensitive methods to quantify low-abundance bacterial biomarkers derived from complex samples are required in clinical, biological, and environmental applications. In this report, a new strategy to integrate sample pretreatment with chemical analysis is investigated using on-line preconcentration with chemical derivatization by CE and UV detection. Single-step enantioselective analysis of muramic acid (MA) and diaminopimelic acid (DAP) was achieved by CE via sample enrichment by dynamic pH junction with ortho-phthalaldehyde/N-acetyl-L-cysteine labeling directly in-capillary. The optimized method resulted in up to a 100-fold enhancement in concentration sensitivity compared to conventional off-line derivatization procedures. The method was also applied toward the detection of micromolar levels of MA and DAP excreted in the extracellular medium of Escherichia coli bacterial cell cultures. On-line preconcentration with chemical derivatization by CE represents a unique approach for conducting rapid, sensitive, and high-throughput analyses of other classes of amino acid and amino sugar metabolites with reduced sample handling, where the capillary functions simultaneously as a concentrator, microreactor, and chiral selector.

  18. An on-line pre-concentration system for determination of cadmium in drinking water using FAAS.

    PubMed

    dos Santos, Walter N L; Costa, Jorge L O; Araujo, Rennan G O; de Jesus, Djane S; Costa, Antônio C S

    2006-10-11

    In the present paper, a minicolumn of polyurethane foam loaded with 4-(2-pyridylazo)-resorcinol (PAR) is proposed as pre-concentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. The optimization step was performed using two-level full factorial design and Doehlert matrix, involving the variables: sampling flow rate, elution concentration, buffer concentration and pH. Using the established experimental conditions in the optimization step of: pH 8.2, sampling flow rate 8.5 mL min(-1), buffer concentration 0.05 mol L(-1) and elution concentration of 1.0 mol L(-1), this system allows the determination of cadmium with detection limit (LD) (3sigma/S) of 20.0 ng L(-1) and quantification limit (LQ) (10sigma/S) of 64 ng L(-1), precision expressed as relative standard deviation (R.S.D.) of 5.0 and 4.7% for cadmium concentration of 5.0 and 40.0 microg L(-1), respectively, and a pre-concentration factor of 158 for a sample volume of 20.0 mL. The accuracy was confirmed by cadmium determination in the standard reference material, NIST SRM 1643d trace elements in natural water. This procedure was applied for cadmium determination in drinking water samples collected from Salvador City, Bahia, Brazil. For five samples analyzed, the achieved concentrations varied from 0.31 to 0.86 microg L(-1).

  19. Application of iminodiacetate chelating resin muromac A-1 in on-line preconcentration and inductively coupled plasma optical emission spectroscopy determination of trace elements in natural waters

    NASA Astrophysics Data System (ADS)

    Vassileva, E.; Furuta, N.

    2003-08-01

    On-line system incorporating a microcolumn of Muromac A-1 resin was used for the developing of method for preconcentration of trace elements followed by inductively coupled plasma (ICP) atomic emission spectrometry determination. A chelating type ion exchange resin has been characterized regarding the sorption and subsequent elution of 24 elements, aiming to their preconcentration from water samples of different origins. The effect of column conditioning, pH and flow rate during the preconcentration step, and the nature of the acid medium employed for desorption of the retained elements were investigated. A sample (pH 5) is pumped through the column at 3 ml min -1 and sequentially eluted directly to the ICP with 3 M HNO 3/HCl mixtures. In order to remove residual matrix elements from the column after sample loading a short buffer wash was found to be necessary. The effectiveness of the matrix separation process was illustrated. The procedure was validated by analyzing several simple matrices, Standard River water sample as well as artificial seawater. Proposed method can be applied for simultaneous determination of In, Tl, Ti, Y, Cd, Co, Cu and Ni in seawater and for multielement trace analysis of river water. Recovery at 1 μg l -1 level for the determination of investigated 24 elements in pure water ranged from 93.1 to 96% except for Pd (82.2%) and Pb (88.1%). For the same concentration level for seawater analysis recovery was between 81.9 and 95.6% except for Hg (38.2%).

  20. Use of Al2O3 in an automated on-line pre-concentration system for determination of cadmium(II) by FAAS.

    PubMed

    Souza, Erica Silva; Martins, Amarildo Otavio; Fajardo, Humberto Vieira; Probst, Luiz Fernando Dias; Carasek, Eduardo

    2008-01-31

    This paper presents the development of an on-line pre-concentration system to determine cadmium(II) in aqueous samples. The analyte was trapped in a mini-column filled with Al(2)O(3) in the form of macro-spheres obtained by the mixture of Al(NO(3))(3).9H(2)O(aq) and chitosan dissolved in acetic acid. The mixture was dropped into an NH(4)OH aqueous solution under rigorous agitation using a peristaltic pump, the macro-spheres were separated from alkaline solution and dried, and finally were submitted to thermal treatment. The pre-concentration system was linear between 1.0 and 100 microg L(-1), with a linearity of 0.999, sensitivity of 3.58 x 10(-3)L microg(-1) and enrichment factor of 21.9. The limits of detection and quantification were 0.08 microg L(-1) and 0.28 microg L(-1), respectively. The repeatability was between 2.6 and 5.9%. Recovery tests were carried out with a real aqueous sample.

  1. Automatic on-line pre-concentration system using a knotted reactor for the FAAS determination of lead in drinking water.

    PubMed

    Souza, Anderson S; Brandão, Geovani C; dos Santos, Walter N L; Lemos, Valfredo A; Ganzarolli, Edgard M; Bruns, Roy E; Ferreira, Sérgio L C

    2007-03-22

    An automatic on-line pre-concentration system is proposed for lead determination in drinking water using flame atomic absorption spectrometry (FAAS). Lead(II) ions are retained as the 1-(2-pyridylazo)-2-naphthol (PAN) complex in the walls of a knotted reactor, followed by an elution step using 0.50molL(-1) hydrochloric acid solution. Optimisation involving the sampling flow rate, pH and buffer concentration factors was performed using a Box-Behnken design. Other factors were established considering results of previous experiments. The procedure allows the determination of lead with a 0.43microgL(-1) detection limit (3sigma/S) and precisions (expressed as relative standard deviation) of 4.84% (N=7) and 2.9% (N=7) for lead concentrations of 5 and 25microgL(-1), respectively. The accuracy was confirmed by the determination of lead in the NIST SRM 1643d trace elements in natural water standard reference material. The pre-concentration factor obtained is 26.5 and the sampling frequency is 48h(-1). The recovery achieved for lead determination in the presence of several ions demonstrated that this procedure could be applied to the analysis of drinking water samples. The method was applied for lead determination in drinking water samples collected in Jequié City, Brazil. The lead concentration found in 25 samples were always lower than the permissible maximum levels stipulated by World Health Organization.

  2. Analysis of total dissolved mercury in waters after on-line preconcentration on an active gold column.

    PubMed

    Zierhut, Anja; Leopold, Kerstin; Harwardt, Lena; Schuster, Michael

    2010-06-15

    A reagent-free fully automated flow injection analysis (FIA) system coupled to atomic fluorescence spectrometry (AFS) for mercury (Hg) quantification is reported, using active nano-structured gold collectors for direct preconcentration of dissolved mercury species from natural waters. Recently we had shown the potential of such an approach for Hg analysis in seawater. This paper now describes the optimisation and validation of the proposed method including the investigation of possible limitations arising with matrix constituents, such as dissolved organic carbon (DOC). A broad variety of water matrices (seawater, river water, moorland water, effluent from wastewater treatment plant) were investigated in order to check the feasibility of the proposed method for total dissolved Hg determination in natural waters. All FIA parameters were optimised by checking Hg recovery in real water samples. Figures of merit of the proposed method - working range, carry over effects, detection limit, reproducibility, etc. - were determined. The method provides a high sensitivity (detection limit: 0.2pgHg) and very good reproducibility (RSD 1.1%, [Hg]=5ngL(-1), n=10). It offers several advantages because no reagents are needed for species conversion, preconcentration, or desorption and therefore the risk of contamination and blank values are lowered, reagent and time consumption are minimized. The system was successfully validated by measurement of a series of recoveries in real waters (all >96%) and in the certified standard reference material BCR 579 (mercury in coastal sea water, recovery 100.5%). Furthermore, the proposed method was applied to 15 real water samples for Hg ultra trace analysis.

  3. Trace elements determination in seawater by ICP-MS with on-line pre-concentration on a Chelex-100 column using a 'standard' instrument setup.

    PubMed

    Søndergaard, Jens; Asmund, Gert; Larsen, Martin M

    2015-01-01

    Trace element determination in seawater is analytically challenging due to the typically very low concentrations of the trace elements and the potential interference of the salt matrix. A common way to address the challenge is to pre-concentrate the trace elements on a chelating resin, then rinse the matrix elements from the resin and subsequently elute and detect the trace elements using inductively coupled plasma mass spectrometry (ICP-MS). This technique typically involves time-consuming pre-treatment of the samples for 'off-line' analyses or complicated sample introduction systems involving several pumps and valves for 'on-line' analyses. As an alternative, the following method offers a simple method for 'on-line' analyses of seawater by ICP-MS. As opposed to previous methods, excess seawater was pumped through the nebulizer of the ICP-MS during the pre-concentration step but the gas flow was adjusted so that the seawater was pumped out as waste without being sprayed into the instrument. Advantages of the method include: •Simple and convenient analyses of seawater requiring no changes to the 'standard' sample introduction system except from a resin-filled micro-column connected to the sample tube. The 'standard' sample introduction system refers to that used for routine digest-solution analyses of biota and sediment by ICP-MS using only one peristaltic pump; and•Accurate determination of the elements V, Mn, Co, Ni, Cu, Zn, Cd and Pb in a range of different seawater matrices verified by participation in 6 successive rounds of the international laboratory intercalibration program QUASIMEME.

  4. Automated on-line preconcentration of trace aqueous mercury with gold trap focusing for cold vapor atomic absorption spectrometry.

    PubMed

    Puanngam, Mahitti; Dasgupta, Purnendu K; Unob, Fuangfa

    2012-09-15

    A fully automated system for the determination of trace mercury in water by cold vapor atomic absorption spectrometry (CVAAS) is reported. The system uses preconcentration on a novel sorbent followed by liberation of the mercury and focusing by a gold trap. Mercury ions were extracted from water samples by passage through a solid phase sorbent column containing 2-(3-(2-aminoethylthio)propylthio)ethanamine modified silica gel. The captured mercury is released by thiourea and then elemental Hg is liberated by sodium borohydride. The vapor phase Hg is recaptured on a gold-plated tungsten filament. This is liberated as a sharp pulse (half-width<2 s) by directly electrically heating the tungsten filament in a dry argon stream. The mercury is measured by CVAAS; no moisture removal is needed. The effects of chloride and selected interfering ions were studied. The sample loading flow rate and argon flow rates for solution purging and filament sweeping were optimized. An overall 50-fold improvement in the limit of detection was observed relative to direct measurement by CVAAS. With a relatively modest multi-user instrument we attained a limit of detection of 35 ng L(-1) with 12% RSD at 0.20 μg L(-1) Hg level. The method was successfully applied to accurately determine sub-μg L(-1) level Hg in standard reference water samples.

  5. Application of multiwall carbon nanotubes impregnated with 5-dodecylsalicylaldoxime for on-line copper preconcentration and determination in water samples by flame atomic absorption spectrometry.

    PubMed

    Tobiasz, Anna; Walas, Stanisław; Soto Hernández, Arlene; Mrowiec, Halina

    2012-07-15

    The paper presents application of multiwall carbon nanotubes (MWCNTs) modified with 5-dodecylsalicylaldoxime to copper(II) flow-injection on-line preconcentration and flame atomic absorption spectrometric (FAAS) determination. Two new sorbents were obtained by impregnation of MWCNTs with Cu(II)-LIX 622(®) complex, however in the first case modification was preceded by carbon wall activation via oxidization (Cu-LIX-CNT-A sorbent), and in the second one no surface activation was performed (Cu-LIX-CNT sorbent). It was found that effective leaching of initially introduced copper and Cu(II) retained in preconcentration process could be realized with the use 7% and 5% (v/v) nitric acid, for particular sorbents. Testing the influence of loading solution pH and rate of loading on sorption it was found out that optimal range of loading solution pH was about 4.5-6.3 for activated and 6.15-6.25 for non-activated CNT. Investigation of sorption kinetics showed that the process can be described by pseudo-second order reaction model. Sorption equilibrium conditions (90% sorption) for LIX-CNT-A and LIX-CNT were obtained after 8-15min, respectively and maximum sorption capacity for the new sorbents amounted to 18.1mgg(-1) and 31.6mgg(-1), respectively. For the examined sorbents enrichment factors increased with extension of loading time up to 180s: linearly for activated and non-linearly for non-activated MWCNTs. Influence of potential interferents such as Cd(II), Zn(II), Fe(III), Mg(II) and Ca(II) ions on copper(II) sorption on the new CNT materials was examined individually and with the use of 2(5-2) factorial design. The study revealed significant interference from iron, magnesium and calcium ions at relatively high concentrations. Applicability of the proposed sorbents was tested for Cu(II) determination in various kinds of water samples and the results were compared with those obtained with the use of ICP MS as a reference technique. Copper(II) determination in two certified

  6. Multielement trace determinations in A1 2O 3 ceramic powders by inductively coupled plasma mass spectrometry with special reference to on-line trace preconcentration

    NASA Astrophysics Data System (ADS)

    Pollmann, D.; Leis, F.; Tölg, G.; Tschöpel, P.; Broekaert, J. A. C.

    1994-12-01

    The use of inductively coupled plasma mass spectrometry (ICP-MS) for the determination of trace elements in Al 2O 3 powders is reported. Special interest is given to a preconcentration of the trace elements by on-line coupling of chromatography to ICP-MS. This is based on the complexation of Co, Cu, Cr, Fe, Ga, Mn, Ni, V and Zn with hexamethylene-dithiocarbamate (HMDC), their preconcentration on a C18 RP column by reversed phase liquid chromatography and their elution with CH 3OH-H 2O mixtures. A direct coupling of the HPLC system to the ICP-MS has been realized by high pressure pneumatic nebulization using desolvation. With the Chromatographie method developed, removal of the AI by at least 99% was achieved. For the trace elements V, Fe, Ni, Co, Cu and Ga, high and reproducible recoveries (ranging from 96-99%) were reached. The method developed has been shown to considerably enhance the power of detection as compared with direct procedures, namely down to 0.02-0.16 ( μg/g for V and Fe, respectively. The possibilities of the method are shown by the determinations of V, Mn, Fe, Ni, Co, Cu, Zn and Ga at the μg/g level in A1 2O 3 powders. The accuracy of the method at the 0.06 to 9.0 μg/g level for Co and Fe, respectively, is demonstrated by a comparison with results of independent methods from the literature.

  7. Micro-scale flow system for on-line multielement preconcentration from saliva digests and determination by inductively coupled plasma optical emission spectrometry

    NASA Astrophysics Data System (ADS)

    Menegário, Amauri A.; Fernanda Giné, Maria

    2001-10-01

    A micro-scale flow system is proposed for on-line preconcentration of Cd, Cu, Mn, Ni and Pb in saliva samples and their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). A small column containing 8 μl of AG50W-X8 resin was inserted into the flow system, assembled with capillary tubes and connected to a micro-concentric nebulizer. The elution of the analytes was performed with 3 mol l -1 HCl at a flow rate of 82 μl min -1. The ICP-OES signal acquisition program permits measurements for 5 s in the concentrated portion of the transient elution peaks. A sample volume of 1 ml was required to obtain enrichment factors of 46, 23, 17, 18 and 44 for Cd, Cu, Mn, Ni and Pb, respectively. The relative standard deviations for a 50-μg l -1 multi-analyte solution were ≤6.5%. The recoveries for Cd, Cu, Mn, Ni and Pb in digested human saliva samples were between 86 and 111%. The sample throughput was 24 h -1.

  8. Combination of two different stationary phases for on-line pre-concentration and separation of basic drugs by using nano-liquid chromatography.

    PubMed

    D'Orazio, Giovanni; Fanali, Salvatore

    2013-04-12

    Capillary columns were packed firstly with silica modified-teicoplanin (teico-CSP) particles for a short zone (1-5 cm) and then with a Cogent Bidentate C18 silica phase (25 cm). The first part of the column (inlet) was intended for focusing the sample model, consisted of selected basic compounds, while the second zone, containing RP18 particles, was used for their separation. For method optimization, some important experimental parameters were studied including the sample solvent, injected volume and teico-CSP particles length. 3 cm teico-CSP resulted to be effective for the on-line pre-concentration, before the separation, of acebutolol, alprenolol, nadolol, oxprenolol and terbutaline with limit of detection at levels of few ng/mL. The comparison of the data obtained in absence of the chiral stationary phase revealed that the use of this chiral short sector into the capillary allowed the increase of the sensitivity of 5-12 times. Injection of larger sample volumes were easily done using higher length of the teico-CSP into the capillary, however the use of 5 cm length was not appropriate because caused the partial chiral separation of some studied compounds.

  9. Determination of chromium(III) and total chromium in seawater by on-line column preconcentration inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Hirata, Shizuko; Honda, Kazuto; Shikino, Osamu; Maekawa, Norihiro; Aihara, Masato

    2000-07-01

    An automated low-pressure flow injection method with on-line column preconcentration using inductively coupled plasma mass spectrometry is described for the determination of chromium(III) and total chromium in seawater. A home-made column of commercially available iminodiacetate resin, Muromac A-1, was used to concentrate chromium(III) in seawater at a pH of 3.0. Following washing of the column with water, the chromium(III) was eluted and transferred to the plasma with 0.70 M nitric acid. Total chromium was determined after the reduction of chromium(VI) to chromium(III) with a 2-mM hydroxylamine solution at pH 1.8. Detection limit (three times the relative standard deviation of the background) of chromium(III) in the artificial seawater based on eight replicate measurements was 0.020 ng ml -1 with a sample loading time of 120 s. The precision was ±1.9%. One sample can be processed in 5 min. Calibration was accomplished by means of artificial seawater. The proposed method was verified by the analysis of two Reference Standard Materials of seawater NASS-4 and CASS-3.

  10. Fast speciation of mercury in seawater by short-column high-performance liquid chromatography hyphenated to inductively coupled plasma spectrometry after on-line cation exchange column preconcentration.

    PubMed

    Jia, Xiao-Yu; Gong, Di-Rong; Han, Yi; Wei, Chao; Duan, Tai-Cheng; Chen, Hang-Ting

    2012-01-15

    A simple and fast method for trace speciation analysis of mercury (Hg(2+)), methylmercury (MeHg(+)) and ethylmercury (EtHg(+)) in seawater has been developed by short-column high-performance liquid chromatography hyphenated to inductively coupled plasma spectrometry (HPLC-ICP-MS) after on-line cation-exchange column (CEC) preconcentration. The analytes were firstly adsorbed on the CEC without any extraneous reagent, and then were eluted rapidly (within seconds) and completely with a very low concentration of l-cysteine solution, which provides the conveniency for the on-line coupling of the preconcentration method and detection technique. To our best knowledge, it is for the first time to employ the CEC preconcentration technique to trap all of the three mercury species simultaneously at their positive charged status for the purpose of speciation analysis. Under the optimized conditions, a very high preconcentration factor up to 1250 has been obtained with 30mL sample solution, which leads to the very low detection limits of 0.042ngL(-1) for Hg(2+), 0.016ngL(-1) for MeHg(+) and 0.008ngL(-1) for EtHg(+) (as Hg), respectively. With the established method, three seawater samples were also analyzed, and all the three mercury species have been found in each sample, albeit at a very low concentration. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

  11. Continuous-flow separation and pre-concentration coupled on-line to solid-surface fluorescence spectroscopy for the simultaneous determination of o-phenylphenol and thiabendazole.

    PubMed

    García Reyes, J F; Llorent Martínez, E J; Ortega Barrales, P; Molina Díaz, A

    2004-01-01

    A novel and single flow-injection system combined with solid-surface fluorescence detection is proposed in this work for the resolution of a mixture of two widely used pesticides (o-phenylphenol and thiabendazole). The continuous-flow methodology is based on the implementation of on-line pre-concentration and separation of both analytes on the surface of C18 silica gel beads placed just inside the flow cell, implemented with gel-phase fluorimetric multi-wavelength detection (using 305/358 and 250/345 nm as excitation/emission wavelengths for thiabendazole and o-phenylphenol, respectively). The separation of the pesticides was possible owing to the different retention/desorption kinetics of their interactions with the solid support in the zone where the stream impinges on the solid material. No previous separation of the analytes before they reach the flow cell is needed thereby simplifying substantially both the procedure and the manifold. By using a sample volume of 2,600 microL, the system was calibrated in the range 0.5-16 and 5-120 ng mL(-1) with detection limits of 0.09 and 0.60 ng mL(-1) for thiabendazole and o-phenylphenol, respectively. The RSD values (n=10) were about 1% for both analytes. The proposed methodology was applied to environmental water samples and also to various commercial pesticide formulations containing both analytes. Recovery percentages were 97-103% and 98-102% for thiabendazole and o-phenylphenol, respectively.

  12. Synthesis and application of chloromethylated polystyrene modified with 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new sorbent for the on-line preconcentration and determination of copper in water, soil, and food samples by FAAS.

    PubMed

    Chamjangali, Mansour Arab; Bagherian, Ghadamali; Mokhlesian, Ali; Bahramian, Bahram

    2011-09-15

    In this paper, we report a simple and sensitive on-line solid phase extraction system for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS). This method is based upon the on-line retention of copper at pH 5.0 on a minicolumn packed with chloromethylated polystyrene modified by 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new solid-phase extraction (SPE) sorbent. The retained Cu(II) ions were eluted with 1.0M HNO(3), and transported directly to FAAS for determination. Several chemical and flow variables were studied and optimized for a quantitative preconcentration and determination of copper(II). At the optimized conditions, for preconcentration of 10.0 mL of a sample solution, a linear calibration graph was obtained over the concentration range of 3.00-120.0 μg L(-1) for Cu(II). The limit of detection (3σ), limit of quantification (10σ), and enrichment factor are 0.56 μg L(-1), 2.0 μg L(-1) and 41, respectively. The relative standard deviation (n = 6) at 20 μg L(-1) of Cu(II) is 2.0%. This method could be applied for determination of trace amounts of Cu(II) in water, soil, and food samples with satisfactory results. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Analysis of biogenic carbonates by inductively coupled plasma-mass spectrometry (ICP-MS). Flow injection on-line solid-phase preconcentration for trace element determination in fish otoliths.

    PubMed

    Arslan, Z; Paulson, A J

    2002-04-01

    The aragonite deposits within the ear bones (otoliths) of teleost fish retain a chemical signal reflecting the life history of fish (similar to rings of trees) and the nature of fish habitats. Otoliths dissolved in acid solutions contain high concentrations of calcium and a variety of proteins. Elimination of matrix salts and organic interferences during preconcentration is essential for accurate determination of trace elements in otolith solutions by inductively coupled plasma-quadrupole mass spectrometry. An iminodiacetate-based chelating resin (Toyopearl AF-Chelate 650 M) has been used for on-line preconcentration and matrix separation for the determination of 31 transition and rare elements. Successful preconcentration of the elements was achieved at pH 5 by on-line buffering, except Mn which required pH 8.8. Sample solutions were loaded on to the column for 1 min at 3.2 mL min(-1), and then eluted directly into the mass spectrometer with 4% v/v nitric acid. This procedure enabled up to 25-fold preconcentration with successful removal of the calcium matrix. The effect of heat-assisted oxidation with concentrated nitric acid was investigated to eliminate the organic matrix. It was found that heating to dryness after dissolution and further mineralization with the acid significantly improved the retention of the transition elements. The method was validated by analysis of a certified reference material produced from saggittal otoliths of emperor snapper ( Lutjanus sebae), and then applied to the determination of trace metal concentrations in juvenile bluefin tuna ( Thunnus thynnus) from the Western Pacific Ocean.

  14. Online coupling of bead injection lab-on-valve analysis to gas chromatography: application to the determination of trace levels of polychlorinated biphenyls in solid waste leachates.

    PubMed

    Quintana, José Benito; Boonjob, Warunya; Miró, Manuel; Cerdà, Víctor

    2009-06-15

    Online sorptive preconcentration exploiting renewable solid surfaces, so-called bead injection (BI), in the miniaturized lab-on-valve (LOV) platform is for the first time hyphenated to gas chromatography (GC) for automated determination of trace level concentrations of organic environmental pollutants. Microfluidic handling of solutions and suspensions in LOV is accomplished by programmable flow with a multisyringe flow injection (MSFI) setup. The method involves the incorporation of minute amounts (3 mg) of reversed-phase copolymeric beads with hydroxylated surface (Bond Elut Plexa) into the channels of a poly(ether imide) LOV microconduit, thus serving as a transient microcolumn packed reactor for preconcentration of organic species. The analyte-loaded beads are afterward eluted with 80 microL of ethyl acetate into a rotary injection valve and subsequently introduced via an air stream into the programmable-temperature vaporizer (PTV) injector of the GC. The used beads are then backflushed and delivered to waste. The GC separation and determination is synchronized with the preconcentration steps of the ensuing sample. The potentials of the devised BI-LOV-GC assembly with electron capture detector for downscaling and automation of sample processing were demonstrated in the determination of polychlorinated biphenyls in raw landfill leachates and a leachate containing the Aroclor 1260 congener mixture. By sampling 12 mL of leachates to which 50 vol % methanol was added to minimize sorption onto the components of the flow network, the automated analytical method features relative recovery percentages >81%, limits of quantification within the range of 0.5-6.1 ng L(-1), relative standard deviations better than 9% at the 50 ng L(-1) level, and 25-fold decrease in cost of solid-phase extraction (SPE) consumables as compared with online robotic systems or dedicated setups.

  15. Trace level determination of cadmium in wine by on-line preconcentration in a 5-Br-PADAP functionalized wool-packed microcolumn coupled to flame atomic absorption spectrometry.

    PubMed

    Monasterio, Romina P; Wuilloud, Rodolfo G

    2009-10-15

    An on-line retention and preconcentration system based on a sheep wool-packed microcolumn combined with flame atomic absorption spectrometry is proposed for trace level determination of Cd in wine. A chelating reagent 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol was immobilized onto the wool before retention of the analyte. Several factors influencing the preconcentration efficiency of Cd and his subsequent determination, such as pH, eluent type, sample and eluent flow rates, interfering effects, were studied. A preconcentration factor of 39 was obtained with only 20 mL of sample. The relative standard deviation for five determinations of 1 microg L(-1) Cd was 3.4%. The calibration graph was linear with a correlation coefficient of 0.998 at levels near the detection limit and up to at least 25 microg L(-1). The limit of detection was 37 ng L(-1). The accuracy of the proposed methodology was tested by comparison of the results with those obtained by electrothermal atomic absorption spectrometry analysis along with a recovery study. Finally, the method was employed for evaluating Cd levels in different wines including, blank, rose, and red.

  16. Grafting 3-mercaptopropyl trimethoxysilane on multi-walled carbon nanotubes surface for improving on-line cadmium(II) preconcentration from water samples.

    PubMed

    Corazza, Marcela Zanetti; Somera, Bruna Fabrin; Segatelli, Mariana Gava; Tarley, Cesar Ricardo Teixeira

    2012-12-01

    In the present study, the performance of multi-walled carbon nanotubes (MWCNTs) grafted with 3-mercaptopropyltrimethoxysilane (3-MPTMS), used as a solid phase extractor for Cd(2+) preconcentration in a flow injection system coupled to flame atomic absorption spectrometry (FAAS), was evaluated. The procedure involved the preconcentration of 20.0 mL of Cd(2+) solution at pH 7.5 (0.1 mol L(-1) buffer phosphate) through 70 mg of 3-MPTMS-grafted MWCNTs packed into a minicolumn at 6.0 mL min(-1). The elution step was carried out with 1.0 mol L(-1) HCl. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to estimate the extent of the MWCNT chemical modification. The 3-MPTMS-grafted MWCNTs provided a 1.68 times improvement in the sensitivity of the Cd(2+) FAAS determination compared to the unsilanized oxidized MWCNTs. The following parameters were obtained: preconcentration factor of 31.5, consumptive index of 0.635 mL, sample throughput of 14 h(-1), and concentration efficiency of 9.46 min(-1). The analytical curve was constructed in the range of 1.0-60.0 μg L(-1) (r=0.9988), and the detection and quantification limits were found to be 0.15 μg L(-1) and 0.62 μg L(-1), respectively. Different types of water samples and cigarette sample were successfully analyzed, and the results were compared using electrothermal atomic absorption spectrometry (ETAAS) as reference technique. In addition, the accuracy of proposed method was also checked by analysis of certified reference material NIST SRM 1573a (tomato leaves) and standard reference material NIST SRM 1643e (trace elements in natural waters). Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Adsorption studies of Cd(II) onto Al 2O 3/Nb 2O 5 mixed oxide dispersed on silica matrix and its on-line preconcentration and determination by flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Mendonça Costa, Lucimara; Ribeiro, Emerson Schwingel; Segatelli, Mariana Gava; do Nascimento, Danielle Raphael; de Oliveira, Fernanda Midori; Tarley, César Ricardo Teixeira

    2011-05-01

    The present study describes the adsorption characteristic of Cd(II) onto Nb 2O 5/Al 2O 3 mixed oxide dispersed on silica matrix. The characterization of the adsorbent has been carried out by infrared spectroscopy (IR), scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), energy dispersive X-ray fluorescence analysis (EDXRF) and specific surface area ( SBET). From batch experiments, adsorption kinetic of Cd(II) was described by a pseudo-second-order kinetic model. The Langmuir linear isotherm fitted to the experimental adsorption isotherm very well, and the maximum adsorption capacity was found to be 17.88 mg g -1. Using the effective material, a method for Cd(II) preconcentration at trace level was developed. The method was based on on-line adsorption of Cd(II) onto SiO 2/Al 2O 3/Nb 2O 5 at pH 8.64, in which the quantitative desorption occurs with 1.0 mol L -1 hydrochloric acid towards FAAS detector. The experimental parameters related to the system were studied by means of multivariate analysis, using 2 4 full factorial design and Doehlert matrix. The effect of SO 42-, Cu 2+, Zn 2+ and Ni 2+ foreign ions showed no interference at 1:100 analyte:interferent proportion. Under the most favorable experimental conditions, the preconcentration system provided a preconcentration factor of 18.4 times, consumption index of 1.08 mL, sample throughput of 14 h -1, concentration efficiency of 4.35 min -1, linear range from 5.0 up to 35.0 μg L -1 and limits of detection and quantification of 0.19 and 0.65 μg L -1 respectively. The feasibility of the proposed method for Cd(II) determination was assessed by analysis of water samples, cigarette sample and certified reference materials TORT-2 (Lobster hepatopancreas) and DOLT-4 (Dogfish liver).

  18. Preparation and characterization of magnetic nanoparticles for the on-line determination of gold, palladium, and platinum in mine samples based on flow injection micro-column preconcentration coupled with graphite furnace atomic absorption spectrometry.

    PubMed

    Ye, Juanjuan; Liu, Shuxia; Tian, Miaomiao; Li, Wanjun; Hu, Bin; Zhou, Weihong; Jia, Qiong

    2014-01-01

    A simple and highly selective procedure for on-line determination of trace levels of Au, Pd, and Pt in mine samples has been developed using flow injection-column adsorption preconcentration coupled with graphite furnace atomic absorption spectrophotometry (FI-column-GFAAS). The precious metals were adsorbed on the as-synthesized magnetic nanoparticles functionalized with 4'-aminobenzo-15-crown-5-ether packed into a micro-column and then eluted with 2% thiourea + 0.1 mol L(-1) HCl solution prior to the determination by GFAAS. The properties of the magnetic adsorbents were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Various experimental parameters affecting the preconcentration of Au, Pd, and Pt were investigated and optimized. Under the optimal experimental conditions, the detection limits of the developed technique were 0.16 ng mL(-1) for Au, 0.28 ng mL(-1) for Pd, and 1.01 ng mL(-1) for Pt, with enrichment factors of 24.3, 13.9, and 17.8, respectively. Precisions, evaluated as repeatability of results, were 1.1%, 3.9%, and 4.4% respectively for Au, Pd, and Pt. The developed method was validated by the analysis of Au, Pd, and Pt in certified reference materials and mine samples with satisfactory results.

  19. Determination of Cd, Co, Cu, Mn, Ni, Pb, and Zn by Inductively Coupled Plasma Mass Spectroscopy or Flame Atomic Absorption Spectrometry after On-line Preconcentration and Solvent Extraction by Flow Injection System

    PubMed

    Bortoli; Gerotto; Marchiori; Mariconti; Palonta; Troncon

    1996-11-01

    The concentrations of Cd, Co, Cu, Mn, Ni, Pb, and Zn in natural and sea waters are too low to be directly determined with by flame atomic absorption spectrometry (FAAS) or graphite furnace atomic absorption spectrometry (GFAAS). Specific sample preparations are requested that make possible the determination of these analytes by preconcentration or extraction. These techniques are affected by severe problems of sample contamination. In this work Cd, Co, Cu, Mn, Ni, Pb, and Zn were determined by inductively coupled plasma mass spectroscopy (ICP-MS) or by atomic absorption spectrometry, in fresh and seawater samples, after on-line preconcentration and following solvent elution with a flow injection system. Bonded silica with octadecyl functional group C18, packed in a microcolumn of 100-μl capacity, was used to collect diethyldithiocarbamate complexes of the heavy metals in aqueous solutions. The metals are complexed with a chelating agent, adsorbed on the C18 column, and eluted with methanol directly in the flow injection system. The methanolic stream can be addressed to FAAS for direct determination of Cu, Ni, and Zn, or collected in a vial for successive analysis by GFAAS. The eluted samples can be also dried in a vacuum container and restored to a little volume with concentrated HNO3 and Milli-Q water for analysis by ICP-MS or GFAAS.

  20. On-line separation and preconcentration of lead(II) by solid-phase extraction using activated carbon loaded with xylenol orange and its determination by flame atomic absorption spectrometry.

    PubMed

    Ensafi, Ali A; Shiraz, A Zendegi

    2008-02-11

    Activated carbon loaded with xylenol orange in a mini-column was used for the highly selective separation and preconcentration of Pb(II) ions. An on-line system for enrichment and the determination of Pb(II) was carried out on flame atomic absorption spectrometry. The conditions of preconcentration and quantitative recovery of Pb(II) from diluted solution, such as pH of aqueous phase, amount of the sorbent, volume of the solutions and flow variables were studied as well as effect of potential interfering ions. Under the optimum conditions, Pb(II) in an aqueous sample was concentrated about 200-fold and the detection limit was 0.4 ng mL(-1) Pb(II). The adsorption capacity of the solid phase was 0.20mg of lead per one gram of the modified activated carbon. The modified activated carbon is stable for several treatments of sample solutions without the need for using any chemical reagent. The recovery of lead(II) from river water, waste water, tap water, and in the following reference materials: SRM 2711 Montana soil and GBW-07605 tea were obtained in the range of 97-104% by the proposed method.

  1. On-line Ultrasound-Assisted Dispersive Micro-Solid-Phase Extraction Based on Amino Bimodal Mesoporous Silica Nanoparticles for the Preconcentration and Determination of Cadmium in Human Biological Samples.

    PubMed

    Shirkhanloo, H; Falahnejad, M; Zavvar Mousavi, H

    2016-06-01

    On-line ultrasound-assisted dispersive micro-solid-phase extraction (USA-DμSPE) has been developed for preconcentration and separation of trace amounts of Cd(II) ions in 0.5 mL of human biological samples. In a syringe with a nylon membrane, new synthetic bulky amino bimodal mesoporous silica nanoparticles (NH2-UVM7) were dispersed as a nanoadsorbent in 5 mL of diluted serum sample (1:10), and after ultrasonic shaking, the liquid phase was separated from the solid phase. At the optimized pH, the chemical and physical adsorption of cadmium ions occurred, respectively, based on complexation with amine groups of UVM7 (Cd:NH2-UVM7) and silica nanoparticles. The analyte was then back-extracted from the sorbent with nitric acid solution (0.2 M), and its concentration was determined by electrothermal atomic absorption spectrometry (ETAAS). Under the optimized conditions, the linear range, limit of detection (LOD), and preconcentration factor (PF) were obtained as 0.01-0.56 μg L(-1), 0.002 μg L(-1), and 25, respectively. The adsorption capacity of NH2-UVM7 was found to be 108.6 mg g(-1) of cadmium. The validation of the methodology was performed by the human standard reference material (HSRM).

  2. Immobilization of proteins on agarose beads, monitored in real time by bead injection spectroscopy

    PubMed Central

    Ruzicka*, Jaromir; Carroll, Andrea D.; Lähdesmäki, Ilkka

    2006-01-01

    Summary This work introduces a novel tool for the examination and optimization of protein immobilization protocols, by measuring the rate and yield of coupling reactions, as they take place on the surface of agarose beads in a well-stirred microreactor. The power of the Bead Injection Spectroscopy (BIS) technique is demonstrated on examples of amino coupling reactions for albumin, ovalbumin, lysozyme, human IgG, ribonuclease A and cytochrome C, using commercially available Aminolink® agarose beads. It was found, surprisingly, that currently recommended protocols for reductive amination can be shortened from several hours to several minutes, and that, contrary to literature data, the yield of coupling is dependent on pH and the isoelectric point of the protein. In addition, leakage of immobilized ligands can be measured by direct spectroscopic interrogation of captured beads in situ. The methodology presented in this work documents that BIS is a useful tool for quality control of agarose-based chromatographic supports, as well as for the optimization of a wide variety of immobilization chemistries, as used for synthesis of chromatographic supports, immobilization of enzymes, and derivatization of biosensing surfaces. PMID:16802025

  3. Online assay of bone specific alkaline phosphatase with a flow injection-bead injection system.

    PubMed

    Hartwell, Supaporn Kradtap; Somprayoon, Duangporn; Kongtawelert, Prachya; Ongchai, Siriwan; Arppornchayanon, Olarn; Ganranoo, Lucksagoon; Lapanantnoppakhun, Somchai; Grudpan, Kate

    2007-09-26

    Alkaline phosphatase (ALP) has been used as one of the biomarkers for bone resorption and liver diseases. Normally, total alkaline phosphatase is quantified along with other symptoms to determine the releasing source of the alkaline phosphatase. A semi-automated flow injection-bead injection system was proposed to conveniently and selectively assay bone alkaline phosphatase (BALP) based on its specific binding to wheat germ coated beads. Amount of BALP in serum was determined from the intensity of the yellow product produced from bound BALP on the retained beads and its substrate pNPP. The used beads were discarded and the fresh ones were introduced for the next analysis. The reaction cell was designed to be opened and closed using a computer controlled solenoid valve for a precise incubation time. The performance of the proposed system was evaluated by using it to assay BALP in human serum. The results were compared to those obtained by using a commercial ELISA kit. The system is proposed to be an easy and cost effective system for quantification of BALP as an alternative to batch wise wheat germ specific binding technique.

  4. Improved method for the determination of zinc pyrithione in environmental water samples incorporating on-line extraction and preconcentration coupled with liquid chromatography atmospheric pressure chemical ionisation mass spectrometry.

    PubMed

    Bones, Jonathan; Thomas, Kevin V; Paull, Brett

    2006-11-03

    A method has been developed for the determination of zinc pyrithione (ZnPT) in environmental water samples using monolithic reversed-phase silica columns for rapid on-line large volume solid phase extraction in tandem with on-line matrix removal using sacrificial strong anion exchange (SAX) columns. This is coupled with reversed-phase liquid chromatography with atmospheric pressure chemical ionisation mass spectrometric detection. Limits of detection in spiked river water samples, using a 200 mL preconcentration volume, were determined as 18 ng L(-1), with a limit of quantitation of 62 ng L(-1). The percentage recovery from spiked river water was found to be 72+/-9 (n=3 extractions), whilst overall method precision, following 10 repeat complete analyses was found to be 27% RSD at 1 microg L(-1). Linearity was determined over the concentration range of 0.25-10 microg L(-1) and the calculated regression coefficient was R(2)=0.9802. The method was used to investigate the environmental fate of zinc pyrithione in waters and its partition coefficient between sediment and water phases.

  5. A simple and sensitive flow-injection on-line preconcentration coupled with hydride generation atomic fluorescence spectrometry for the determination of ultra-trace lead in water, wine, and rice.

    PubMed

    Wu, Hong; Jin, Yan; Luo, Mingbiao; Bi, Shuping

    2007-09-01

    A simple and sensitive flow-injection on-line separation and preconcentration system coupled to hydride generation atomic fluorescence spectrometry (HG-AFS) was developed for ultra-trace lead determination in water, wine, and rice samples, with the salient advantages of its minimization of transition-metal interferences and tolerance to an ethanol matrix. A lead hydroxide precipitate was achieved by the on-line merging of a sample and an ammonium buffer solution and collected onto the inner walls of a knotted reactor (KR). Removal of the residual solution from KR was achieved by air flow, and dissolution of the precipitate was carried out by using 0.2 mol l(-1) HCl. With a sample consumption of 11.7 ml, an enhancement factor of 16 was obtained at a sample throughput of 30 h(-1). The limit of detection (3s) was 16 ng l(-1) and the precision (RSD) for 1.0 microg l(-1) Pb was 3.4%.

  6. Quantitative on-line preconcentration-liquid chromatography coupled with tandem mass spectrometry method for the determination of pharmaceutical compounds in water.

    PubMed

    Idder, Salima; Ley, Laurent; Mazellier, Patrick; Budzinski, Hélène

    2013-12-17

    One of the current environmental issues concerns the presence and fate of pharmaceuticals in water bodies as these compounds may represent a potential environmental problem. The characterization of pharmaceutical contamination requires powerful analytical method able to quantify these pollutants at very low concentration (few ng L(-1)). In this work, a multi-residue analytical methodology (on-line solid phase extraction-liquid chromatography-triple quadrupole mass spectrometry using positive and negative electrospray ionization) has been developed and validated for 40 multi-class pharmaceuticals and metabolites for tap and surface waters. This on-line SPE method was very convenient and efficient compared to classical off-line SPE method because of its shorter total run time including sample preparation and smaller sample volume (1 mL vs up to 1 L). The optimized method included several therapeutic classes as lipid regulators, antibiotics, beta-blockers, non-steroidal anti-inflammatories, antineoplastic, etc., with various physicochemical properties. Quantification has been achieved with the internal standards. The limits of detection are between 0.7 and 15 ng L(-1) for drinking waters and 2-15 ng L(-1) for surface waters. The inter-day precision values are below 20% for each studied level. The improvement and strength of the analytical method has been verified along a monitoring of these 40 pharmaceuticals in Isle River, a French stream located in the South West of France. During this survey, 16 pharmaceutical compounds have been detected. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Determination of rare earth elements in seawater by inductively coupled plasma mass spectrometry with on-line column pre-concentration using 8-quinolinole-immobilized fluorinated metal alkoxide glass

    NASA Astrophysics Data System (ADS)

    Kajiya, Tasuku; Aihara, Masato; Hirata, Shizuko

    2004-04-01

    The on-line column pre-concentration technique with inductively coupled plasma mass spectrometry (ICP-MS) has been developed using micro-column of 8-quinolinole-immobilized fluorinated metal alkoxide glass (MAF-8HQ). The aim of method was to determine rare earth elements (REEs) (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in seawater. A 6.4 ml of seawater sample was passed through the column for 2 min, after washing the column with ultrapure water, the adsorbed REEs were subsequently eluted into the plasma with 1.4 M nitric acid. Sample pH, sampling and eluting flow rates and acidity of eluent were optimized. Detection limits (3 σ) based on three times standard deviations of water by 8 replicates were in the range from 0.11 pg ml -1 for Y to 0.30 pg ml -1 for Tb, and the precisions by a 10 pg ml -1 REEs standard solution ( n=8) were in the range from 4.7% for Tm to 8.7% for Tb and Yb. Analysis of one sample could be processed in 7 min. The proposed method was verified by determination of REEs in the two certified reference materials (CRMs) of seawater, CASS-4 and NASS-5, and the method was also applied to determine REEs in the costal seawater of Hiroshima Bay, the Seto Inland Sea, Japan.

  8. Determination of Hg(2+) by on-line separation and pre-concentration with atmospheric-pressure solution-cathode glow discharge atomic emission spectrometry.

    PubMed

    Li, Qing; Zhang, Zhen; Wang, Zheng

    2014-10-03

    A simple and sensitive method to determine Hg(2+) was developed by combining solution-cathode glow discharge atomic emission spectrometry (SCGD-AES) with flow injection (FI) based on on-line solid-phase extraction (SPE). We synthesized l-cysteine-modified mesoporous silica and packed it in an SPE microcolumn, which was experimentally determined to possess a good mercury adsorption capacity. An enrichment factor of 42 was achieved under optimized Hg(2+) elution conditions, namely, an FI flow rate of 2.0 mL min(-1) and an eluent comprised of 10% thiourea in 0.2 mol L(-1) HNO3. The detection limit of FI-SCGD-AES was determined to be 0.75 μg L(-1), and the precision of the 11 replicate Hg(2+) measurements was 0.86% at a concentration of 100 μg L(-1). The proposed method was validated by determining Hg(2+) in certified reference materials such as human hair (GBW09101b) and stream sediment (GBW07310).

  9. Preparation and evaluation of open tubular C18-silica monolithic microcartridges for preconcentration of peptides by on-line solid phase extraction capillary electrophoresis.

    PubMed

    Ortiz-Villanueva, Elena; Benavente, Fernando; Giménez, Estela; Yilmaz, Fatma; Sanz-Nebot, Victoria

    2014-10-10

    In this study, C18-silica monoliths were synthesized as a porous layer in open tubular capillary columns, to be cut later into microcartridges for the analysis of neuropeptides by on-line solid-phase extraction capillary electrophoresis with UV and MS detection (SPE-CE-UV and SPE-CE-MS). First, several types of C18-silica monolithic (MtC18) microcartridges were used to analyse standard solutions of five neuropeptides (i.e. dynorphin A (1-7), substance P (7-11), endomorphin 1, methionine enkephalin and [Ala]-methionine enkephalin). The MtC18 sorbents were especially selective against endomorphin 1 and substance P (7-11)). The best results in terms of sensitivity and inter-microcartridge reproducibility were achieved with the microcartridges obtained from a 10-cm open tubular capillary column with a thin monolithic coating with large through-pores (1-5μm). Run-to-run repeatability, microcartridge durability, linearity ranges and LODs were studied by MtC18-SPE-CE-MS. As expected due to their greater selectivity, the best LOD enhancement was obtained for End1 and SP (7-11) (50 times with regard to CE-MS). Finally, the suitability of the methodology for analysing biological fluids was tested with plasma samples spiked with End1 and SP (7-11). Results obtained were promising because both neuropeptides could be detected at 0.05μgmL(-1), which was almost the same concentration level as for the standard solutions (0.01μgmL(-1)).

  10. Biological preconcentrator

    DOEpatents

    Manginell, Ronald P.; Bunker, Bruce C.; Huber, Dale L.

    2008-09-09

    A biological preconcentrator comprises a stimulus-responsive active film on a stimulus-producing microfabricated platform. The active film can comprise a thermally switchable polymer film that can be used to selectively absorb and desorb proteins from a protein mixture. The biological microfabricated platform can comprise a thin membrane suspended on a substrate with an integral resistive heater and/or thermoelectric cooler for thermal switching of the active polymer film disposed on the membrane. The active polymer film can comprise hydrogel-like polymers, such as poly(ethylene oxide) or poly(n-isopropylacrylamide), that are tethered to the membrane. The biological preconcentrator can be fabricated with semiconductor materials and technologies.

  11. Sequential injection-bead injection-lab-on-valve coupled to high-performance liquid chromatography for online renewable micro-solid-phase extraction of carbamate residues in food and environmental samples.

    PubMed

    Vichapong, Jitlada; Burakham, Rodjana; Srijaranai, Supalax; Grudpan, Kate

    2011-07-01

    A sequential injection-bead injection-lab-on-valve system was hyphenated to HPLC for online renewable micro-solid-phase extraction of carbamate insecticides. The carbamates studied were isoprocarb, methomyl, carbaryl, carbofuran, methiocarb, promecarb, and propoxur. LiChroprep(®) RP-18 beads (25-40 μm) were employed as renewable sorbent packing in a microcolumn situated inside the LOV platform mounted above the multiposition valve of the sequential injection system. The analytes sorbed by the microcolumn were eluted using 80% acetonitrile in 0.1% acetic acid before online introduction to the HPLC system. Separation was performed on an Atlantis C-18 column (4.6 × 150 mm, 5 μm) utilizing gradient elution with a flow rate of 1.0 mL/min and a detection wavelength at 270 nm. The sequential injection system offers the means of performing automated handling of sample preconcentration and matrix removal. The enrichment factors ranged between 20 and 125, leading to limits of detection (LODs) in the range of 1-20 μg/L. Good reproducibility was obtained with relative standard deviations of <0.7 and 5.4% for retention time and peak area, respectively. The developed method has been successfully applied to the determination of carbamate residues in fruit, vegetable, and water samples.

  12. Chemical preconcentrator

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.

    2001-01-01

    A chemical preconcentrator is disclosed with applications to chemical sensing and analysis. The preconcentrator can be formed by depositing a resistive heating element (e.g. platinum) over a membrane (e.g. silicon nitride) suspended above a substrate. A coating of a sorptive material (e.g. a microporous hydrophobic sol-gel coating or a polymer coating) is formed on the suspended membrane proximate to the heating element to selective sorb one or more chemical species of interest over a time period, thereby concentrating the chemical species in the sorptive material. Upon heating the sorptive material with the resistive heating element, the sorbed chemical species are released for detection and analysis in a relatively high concentration and over a relatively short time period. The sorptive material can be made to selectively sorb particular chemical species of interest while not substantially sorbing other chemical species not of interest. The present invention has applications for use in forming high-sensitivity, rapid-response miniaturized chemical analysis systems (e.g. a "chem lab on a chip").

  13. Particle preconcentrator

    SciTech Connect

    Linker, K.L.; Conrad, F.J.; Custer, C.A.; Rhykerd, C.L. Jr

    2000-07-11

    An apparatus and method are disclosed for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a previous screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  14. Particle preconcentrator

    DOEpatents

    Linker, K.L.; Conrad, F.J.; Custer, C.A.; Rhykerd, C.L. Jr.

    1998-12-29

    An apparatus and method are disclosed for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents. 3 figs.

  15. Particle preconcentrator

    DOEpatents

    Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

    1998-01-01

    An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  16. Particle preconcentrator

    DOEpatents

    Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

    2000-01-01

    An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  17. Particle preconcentrator

    SciTech Connect

    Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

    2005-09-20

    An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  18. Exploiting the bead injection concept for sequential determination of copper and mercury ions in river-water samples.

    PubMed

    Vidotti, Eliane C; Almeida, Vitor C; Oliveira, Cláudio C

    2004-11-15

    A procedure involving bead-injection concept and sequential determination of copper and mercury ions in river-water samples is proposed. The method is based on the solid-phase extraction of both metal ions on the same beads surface (Chelex 100 resin) and in their subsequent reaction with the colorimetric reagents (APDC and Dithizone for copper and mercury ions, respectively). For this task, a resin mini-column is established in the optical path by the selection, introduction and trapping of a defined volume of the Chelex-100 resin beads suspension in the flow system. The passage of the sample solution through the resin mini-column promotes the sorption of Cu(II) ions and, making the APDC colorimetric reagent flows through the beads, the formation of the coloured complex on the solid phase surface occurs. The absorbance of the formed APDC-Cu complex is then monitored at 436nm and the spent beads are discarded. Packing another resin mini-column in the flow cell and repeating the concentration step it is possible to carried out the mercury determination by using Dithizone as reagent. The absorbance of the Dithizone-Hg complex is monitored at 500nm. After each measurement, the spent beads are wasted and a new portion of fresh one is trapped in the system, letting it ready for the next measurement. The bead injection system is versatile and can be used to concentrate different sample volumes, which permits the determination of a wide range of copper and mercury ions concentrations. When the sample-selected volumes are 100 and 1000mul the analytical ranges were 5.0 up to 500.0mugl(-1) and 2.5 up to 30.0mugl(-1) for Cu(II) and Hg(II) ions, respectively. Under these conditions, the detection limit was estimated as 0.63 and 0.25mugl(-1) for copper and mercury ions determination. The system consumes 2mg of Chelex 100 resin beads, 0.20mg of APDC or 1.25mg of Dithizone per determination and the traditional organic solvent extraction methodology, normally used in connection

  19. Micro-bead injection spectroscopy for label-free automated determination of immunoglobulin G in human serum.

    PubMed

    Ramos, Inês I; Magalhães, Luís M; Barreiros, Luisa; Reis, Salette; Lima, José L F C; Segundo, Marcela A

    2017-09-09

    Immunoglobulin G (IgG) represents the major fraction of antibodies in healthy adult human serum, and deviations from physiological levels are a generic marker of disease corresponding to different pathologies. Therefore, screening methods for IgG evaluation are a valuable aid to diagnostics. The present work proposes a rapid, automatic, and miniaturized method based on UV-vis micro-bead injection spectroscopy (μ-BIS) for the real-time determination of human serum IgG with label-free detection. Relying on attachment of IgG in rec-protein G immobilized in Sepharose 4B, a bioaffinity column is automatically assembled, where IgG is selectively retained and determined by on-column optical density measurement. A "dilution-and-shoot" approach (50 to 200 times) was implemented without further sample treatment because interferences were flushed out of the column upon sample loading, with minimization of carryover and cross-contamination by automatically discarding the sorbent (0.2 mg) after each determination. No interference from human serum albumin at 60 mg mL(-1) in undiluted sample was found. The method allowed IgG determination in the range 100-300 μg mL(-1) (corresponding to 5.0-60 mg mL(-1) in undiluted samples), with a detection limit of 33 μg mL(-1) (1.7 mg mL(-1) for samples, dilution factor of 50). RSD values were < 9.4 and < 11.7%, for intra and inter-assay precision, respectively, while recovery values for human serum spiked with IgG at high pathological levels were 97.8-101.4%. Comparison to commercial ELISA kit showed no significant difference for tested samples (n = 8). Moreover, time-to-result decreased from several hours to < 5 min and analysis cost decreased 10 times, showing the potential of the proposed approach as a point-of-care method. Graphical abstract Micro-Bead Injection Spectroscopy method for real time, automated and label-free determination of total serum human Immunoglobulin G (IgG). The method was designed for Lab

  20. Determination of amprolium in egg yolk and muscle tissue (chicken) by HPLC with post-column reaction and fluorometric detection, using on-line sample clean-up and pre-concentration steps.

    PubMed

    van Leeuwen, W; Wilhelmus van Gend, H

    1988-06-01

    A continuous flow system was coupled to a high-pressure liquid chromatography (HPLC) system, resulting in an automated system for the determination of amprolium in egg yolk and (chicken) muscle tissue. The sample was diluted (yolk) or extracted (tissue) with water, and the solution obtained was dialysed against water as the recipient stream. Aliquots of the dialysed solutions were pumped onto a short pre-concentration column. By means of the mobile phase, the concentrate was back-flushed onto the analytical column and amprolium was separated from interfering substances, using a reversed phase ion-pair system. Amprolium was post-column oxidized to amprochrome, which was detected fluorometrically. Linear calibration curves for both yolk an muscle tissue were obtained in the 10-250 micrograms/kg range. The detection limit is approximately 3 micrograms/kg. This method was applied to eggs and muscle tissue, which were commercial obtained. Egg yolk was found to be frequently contaminated with low levels of amprolium (29.4% positive of 266 samples investigated; mean concentration of positive samples = 58 micrograms/kg), whereas only a few muscle samples contained detectable levels (4.9% positive of 81 samples investigated; mean concentration of positive samples = 5 micrograms/kg).

  1. Tortuous path chemical preconcentrator

    DOEpatents

    Manginell, Ronald P.; Lewis, Patrick R.; Adkins, Douglas R.; Wheeler, David R.; Simonson, Robert J.

    2010-09-21

    A non-planar, tortuous path chemical preconcentrator has a high internal surface area having a heatable sorptive coating that can be used to selectively collect and concentrate one or more chemical species of interest from a fluid stream that can be rapidly released as a concentrated plug into an analytical or microanalytical chain for separation and detection. The non-planar chemical preconcentrator comprises a sorptive support structure having a tortuous flow path. The tortuosity provides repeated twists, turns, and bends to the flow, thereby increasing the interfacial contact between sample fluid stream and the sorptive material. The tortuous path also provides more opportunities for desorption and readsorption of volatile species. Further, the thermal efficiency of the tortuous path chemical preconcentrator is comparable or superior to the prior non-planar chemical preconcentrator. Finally, the tortuosity can be varied in different directions to optimize flow rates during the adsorption and desorption phases of operation of the preconcentrator.

  2. Methods for improved preconcentrators

    DOEpatents

    Manginell, Ronald P.; Lewis, Patrick R.; Okandan, Murat

    2010-06-01

    The present invention relates generally to chemical analysis (e.g. by gas chromatography), and in particular to a compact chemical preconcentrator formed on a substrate with a heatable sorptive membrane that can be used to accumulate and concentrate one or more chemical species of interest over time and then rapidly release the concentrated chemical species upon demand for chemical analysis.

  3. Determination of salivary cotinine through solid phase extraction using a bead-injection lab-on-valve approach hyphenated to hydrophilic interaction liquid chromatography.

    PubMed

    Ramdzan, Adlin N; Barreiros, Luísa; Almeida, M Inês G S; Kolev, Spas D; Segundo, Marcela A

    2016-01-15

    Cotinine, the first metabolite of nicotine, is often used as a biomarker in the monitoring of environmental tobacco smoke (ETS) exposure due to its long half-life. This paper reports on the development of an at-line automatic micro-solid phase extraction (μSPE) method for the determination of salivary cotinine followed by its analysis via hydrophilic interaction liquid chromatography (HILIC). The SPE methodology is based on the bead injection (BI) concept in a mesofluidic lab-on-valve (LOV) flow system to automatically perform all SPE steps. Three commercially available reversed-phase sorbents were tested, namely, Oasis HLB, Lichrolut EN and Focus, and the spherically shaped sorbents (i.e., Oasis HLB and Focus) provided better packing within the SPE column and hence higher column efficiency. An HILIC column was chosen based on its potential for achieving higher sensitivity and better retention of polar compounds such as cotinine. The method uses an isocratic program with acetonitrile:100mM ammonium acetate buffer, pH 5.8 in 95:5 v/v ratio as the mobile phase at a flow rate of 1.0 mL min(-1). Using this approach, the linear calibration range was from 10 to 1000 ng which corresponded to 5-500 μg L(-1). The corresponding μSPE-BI-LOV system was proven to be reliable in the handing and analysis of viscous biological samples such as saliva, achieving a sampling rate of 6h(-1) and a limit of detection and quantification of 1.5 and 3μgL(-1), respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Human portable preconcentrator system

    DOEpatents

    Linker, Kevin L.; Bouchier, Francis A.; Hannum, David W.; Rhykerd, Jr., Charles L.

    2003-01-01

    A preconcentrator system and apparatus suited to human portable use wherein sample potentially containing a target chemical substance is drawn into a chamber and through a pervious screen. The screen is adapted to capture target chemicals and then, upon heating, to release those chemicals into the chamber. Chemicals captured and then released in this fashion are then carried to a portable chemical detection device such as a portable ion mobility spectrometer. In the preferred embodiment, the means for drawing sample into the chamber comprises a reversible fan which, when operated in reverse direction, creates a backpressure that facilitates evolution of captured target chemicals into the chamber when the screen is heated.

  5. Non-planar chemical preconcentrator

    DOEpatents

    Manginell, Ronald P.; Adkins, Douglas R.; Sokolowski, Sara S.; Lewis, Patrick R.

    2006-10-10

    A non-planar chemical preconcentrator comprises a high-surface area, low mass, three-dimensional, flow-through sorption support structure that can be coated or packed with a sorptive material. The sorptive material can collect and concentrate a chemical analyte from a fluid stream and rapidly release it as a very narrow temporal plug for improved separations in a microanalytical system. The non-planar chemical preconcentrator retains most of the thermal and fabrication benefits of a planar preconcentrator, but has improved ruggedness and uptake, while reducing sorptive coating concerns and extending the range of collectible analytes.

  6. Human portable preconcentrator system

    DOEpatents

    Linker, Kevin L.; Brusseau, Charles A.; Hannum, David W.; Puissant, James G.; Varley, Nathan R.

    2003-08-12

    A preconcentrator system and apparatus suited to human portable use wherein sample potentially containing a target chemical substance is drawn into a chamber and through a pervious screen. The screen is adapted to capture target chemicals and then, upon heating, to release those chemicals into the chamber. Chemicals captured and then released in this fashion are then carried to a portable chemical detection device such as a portable ion mobility spectrometer. In the preferred embodiment, the means for drawing sample into the chamber comprises a reversible fan which, when operated in reverse direction, creates a backpressure that facilitates evolution of captured target chemicals into the chamber when the screen is heated. The screen can be positioned directly in front of the detector prior to heating to improve detection capability.

  7. Integrating preconcentrator heat controller

    DOEpatents

    Bouchier, Francis A.; Arakaki, Lester H.; Varley, Eric S.

    2007-10-16

    A method and apparatus for controlling the electric resistance heating of a metallic chemical preconcentrator screen, for example, used in portable trace explosives detectors. The length of the heating time-period is automatically adjusted to compensate for any changes in the voltage driving the heating current across the screen, for example, due to gradual discharge or aging of a battery. The total deposited energy in the screen is proportional to the integral over time of the square of the voltage drop across the screen. Since the net temperature rise, .DELTA.T.sub.s, of the screen, from beginning to end of the heating pulse, is proportional to the total amount of heat energy deposited in the screen during the heating pulse, then this integral can be calculated in real-time and used to terminate the heating current when a pre-set target value has been reached; thereby providing a consistent and reliable screen temperature rise, .DELTA.T.sub.s, from pulse-to-pulse.

  8. Mass-sensitive chemical preconcentrator

    DOEpatents

    Manginell, Ronald P.; Adkins, Douglas R.; Lewis, Patrick R.

    2007-01-30

    A microfabricated mass-sensitive chemical preconcentrator actively measures the mass of a sample on an acoustic microbalance during the collection process. The microbalance comprises a chemically sensitive interface for collecting the sample thereon and an acoustic-based physical transducer that provides an electrical output that is proportional to the mass of the collected sample. The acoustic microbalance preferably comprises a pivot plate resonator. A resistive heating element can be disposed on the chemically sensitive interface to rapidly heat and release the collected sample for further analysis. Therefore, the mass-sensitive chemical preconcentrator can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  9. Flow-injection sample preconcentration for ion-pair chromatography of trace metals in waters.

    PubMed

    Pobozy, Ewa; Halko, Radoslav; Krasowski, Marcin; Wierzbicki, Tomasz; Trojanowicz, Marek

    2003-05-01

    Selected trace transition metal ions have been determined in an FIA/HPLC hyphenated system using on-line preconcentration on cellulose functionalised sorbent Cellex P. For HPLC separation ion-pair chromatography was employed with spectrophotometric detection at 510 nm using post-column derivatisation with PAR. Favourable kinetic conditions of sorption and elution as well as optimisation of hyphenated system allowed to obtain detection limits at sub-microgL(-1) level at 25 min preconcentration time. The developed method was employed for determination of Co(II), Ni(II), Cd(II) and Mn(II) in river water with reasonable agreement of obtained results with electrothermal AAS determination.

  10. Chemical preconcentrator with integral thermal flow sensor

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.

    2003-01-01

    A chemical preconcentrator with integral thermal flow sensor can be used to accurately measure fluid flow rate in a microanalytical system. The thermal flow sensor can be operated in either constant temperature or constant power mode and variants thereof. The chemical preconcentrator with integral thermal flow sensor can be fabricated with the same MEMS technology as the rest of the microanlaytical system. Because of its low heat capacity, low-loss, and small size, the chemical preconcentrator with integral thermal flow sensor is fast and efficient enough to be used in battery-powered, portable microanalytical systems.

  11. Simultaneous sample preconcentration and matrix removal using field-flow fractionation coupled to inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Al-Ammar, Assad; Siripinyanond, Atitaya; Barnes, Ramon M.

    2001-10-01

    An on-channel sample preconcentration-matrix removal arrangement, based on coupling field-flow fractionation (FFF) to inductively coupled plasma mass spectrometry (ICP-MS), has been constructed for on-line sample pretreatment ICP-MS trace element determination. A commercial FFF system is modified to incorporate an on-channel preconcentration procedure allowing injection of up to 50 ml of sample, which could be preconcentrated by 50-1400 fold. A high molecular weight complexing agent added to the sample forms strong complexes with the measured trace analytes but not with the sample matrix. When the sample-complexing agent mixture is introduced to the FFF unit, the uncomplexed matrix element is removed by permeation through a membrane that separates the FFF sample compartment. The trace analytes remain in the FFF channel, because their high molecular weight complexes do not permeate through the membrane. Preconcentration and matrix elimination occur simultaneously. The matrix-free, preconcentrated sample is introduced directly to the ICP-MS nebulizer. The method was tested using 10-ml sample aliquots that contain As, Cd, Cu, Mo, Pb, Re, Sn, Te, Tl, Y, Zn and Zr analytes and 5000 mg l -1 Ca or Na matrices and ethylene imine polymer complexing agent. Copper and Re isotopic ratio values in reference standards also were determined after preconcentration and matrix element removal.

  12. Preconcentration modeling for the optimization of a micro gas preconcentrator applied to environmental monitoring.

    PubMed

    Camara, Malick; Breuil, Philippe; Briand, Danick; Viricelle, Jean-Paul; Pijolat, Christophe; de Rooij, Nico F

    2015-04-21

    This paper presents the optimization of a micro gas preconcentrator (μ-GP) system applied to atmospheric pollution monitoring, with the help of a complete modeling of the preconcentration cycle. Two different approaches based on kinetic equations are used to illustrate the behavior of the micro gas preconcentrator for given experimental conditions. The need for high adsorption flow and heating rate and for low desorption flow and detection volume is demonstrated in this paper. Preliminary to this optimization, the preconcentration factor is discussed and a definition is proposed.

  13. High throughput liquid absorption preconcentrator sampling instrument

    DOEpatents

    Zaromb, Solomon; Bozen, Ralph M.

    1992-01-01

    A system for detecting trace concentrations of an analyte in air includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container comprising a wettable material. The wettable material is continuously wetted with an analyte-sorbing liquid which flows from one part of the container to a lower end. Sampled air flows through the container in contact with the wetted material with a swirling motion which results in efficient transfer of analyte vapors or aerosol particles to the sorbing liquid and preconcentration of traces of analyte in the liquid. The preconcentrated traces of analyte may be either detected within the container or removed therefrom for injection into a separate detection means or for subsequent analysis.

  14. Large-volume sampling and preconcentration for trace explosives detection.

    SciTech Connect

    Linker, Kevin Lane

    2004-05-01

    A trace explosives detection system typically contains three subsystems: sample collection, preconcentration, and detection. Sample collection of trace explosives (vapor and particulate) through large volumes of airflow helps reduce sampling time while increasing the amount of dilute sample collected. Preconcentration of the collected sample before introduction into the detector improves the sensitivity of the detector because of the increase in sample concentration. By combining large-volume sample collection and preconcentration, an improvement in the detection of explosives is possible. Large-volume sampling and preconcentration is presented using a systems level approach. In addition, the engineering of large-volume sampling and preconcentration for the trace detection of explosives is explained.

  15. Theoretical models for trace gas preconcentrators

    NASA Astrophysics Data System (ADS)

    Kim, Jihyun

    2013-11-01

    Muntz et al., in 2004 and 2011, had attempted to describe theoretical models about the shape of a main flow channel and the concentration ratio of trace gas for a Continuous Flow-Through Trace Gas Preconcentrator by concepts of net flux and mass flow rate respectively. The possibilities were suggested to obtain theoretical models for the preconcentrator even through they were not satisfied with experimental results, because the theoretical models were only considered for free molecular flow. In this study, new theoretical models based on net flux and mass flow rate have been applied for each regime; free molecular flow, transition flow, and hydrodynamic flow. There are comprehensive numerical models to describe entire regimes with the new theoretical models induced by mass flow rate, but the new theoretical models induced by net flux can be only obtained for the hydrodynamic flow. The numerical predictions were compared with existing experimental results of the prototype of the preconcentrator. The numerical predictions of hydrodynamic and transition flows by mass flow rate were close to the experimental results, but other cases were different to the experimental data. Nevertheless, the theoretical models can provide the possibility to develop the theory of preconcentrator.

  16. Sample preconcentration with chemical derivatization in capillary electrophoresis. Capillary as preconcentrator, microreactor and chiral selector for high-throughput metabolite screening.

    PubMed

    Ptolemy, Adam S; Britz-McKibbin, Philip

    2006-02-17

    New strategies for integrating sample pretreatment with chemical analyses under a single format is required for rapid, sensitive and enantioselective analyses of low abundance metabolites in complex biological samples. Capillary electrophoresis (CE) offers a unique environment for controlling analyte/reagent band dispersion and electromigration properties using discontinuous electrolyte systems. Recent work in our laboratory towards developing a high-throughput CE platform for low abundance metabolites via on-line sample preconcentration with chemical derivatization (SPCD) is primarily examined in this review, as there have been surprisingly only a few strategies reported in the literature to date. In-capillary sample preconcentration serves to enhance concentration sensitivity via electrokinetic focusing of long sample injection volumes for lower detection limits, whereas chemical derivatization by zone passing is used to expand detectability and selectivity, notably for enantiomeric resolution of metabolites lacking intrinsic chromophores using nanolitre volumes of reagent. Together, on-line SPCD-CE can provide over a 100-fold improvement in concentration sensitivity, shorter total analysis times, reduced sample handling and improved reliability for a variety of amino acid and amino sugar metabolites, which is also amenable to automated high-throughput screening. This review will highlight basic method development and optimization parameters relevant to SPCD-CE, including applications to bacterial metabolite flux and biomarker analyses. Insight into the mechanism of analyte focusing and labeling by SPCD-CE is also discussed, as well as future directions for continued research.

  17. Preconcentration and separation of analytes in microchannels

    DOEpatents

    Hatch, Anson; Singh, Anup K.; Herr, Amy E.; Throckmorton, Daniel J.

    2010-11-09

    Disclosed herein are methods and devices for preconcentrating and separating analytes such as proteins and polynucleotides in microchannels. As disclosed, at least one size-exclusion polymeric element is adjacent to processing area or an assay area in a microchannel which may be porous polymeric element. The size-exclusion polymeric element may be used to manipulate, e.g. concentrate, analytes in a sample prior to assaying in the assay area.

  18. Liquid-absorption preconcentrator sampling instrument

    DOEpatents

    Zaromb, S.

    1990-12-11

    A system is described for detecting trace concentrations of an analyte in air and includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container in which is disposed a wettable material extending substantially the entire length of the container. One end of the wettable material is continuously wetted with an analyte-sorbing liquid, which flows to the other end of the container. Sample air is flowed through the container in contact with the wetted material for trapping and preconcentrating the traces of analyte in the sorbing liquid, which is then collected at the other end of the container and discharged to the detector. The wetted material may be a wick comprising a bundle of fibers, one end of which is immersed in a reservoir of the analyte-sorbing liquid, or may be a liner disposed on the inner surface of the container, with the sorbing liquid being centrifugally dispersed onto the liner at one end thereof. The container is preferably vertically oriented so that gravity effects the liquid flow. 4 figs.

  19. Liquid-absorption preconcentrator sampling instrument

    DOEpatents

    Zaromb, Solomon

    1990-01-01

    A system for detecting trace concentrations of an analyte in air and includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container in which is disposed a wettable material extending substantially the entire length of the container. One end of the wettable material is continuously wetted with an analyte-sorbing liquid, which flows to the other end of the container. Sample air is flowed through the container in contact with the wetted material for trapping and preconcentrating the traces of analyte in the sorbing liquid, which is then collected at the other end of the container and discharged to the detector. The wetted material may be a wick comprising a bundle of fibers, one end of which is immersed in a reservoir of the analyte-sorbing liquid, or may be a liner disposed on the inner surface of the container, with the sorbing liquid being centrifugally dispersed onto the liner at one end thereof. The container is preferably vertically oriented so that gravity effects the liquid flow.

  20. A MEMS Based Hybrid Preconcentrator/Chemiresistor Chemical Sensor

    SciTech Connect

    HUGHES,ROBERT C.; PATEL,SANJAY V.; MANGINELL,RONALD P.

    2000-06-12

    A hybrid of a microfabricated planar preconcentrator and a four element chemiresistor array chip has been fabricated and the performance as a chemical sensor system has been demonstrated. The close proximity of the chemiresistor sensor to the preconcentrator absorbent layer allows for fast transfer of the preconcentrated molecules during the heating and resorption step. The hybrid can be used in a conventional flow sampling system for detection of low concentrations of analyte molecules or in a pumpless/valveless mode with a grooved lid to confine the desorption plume from the preconcentrator during heating.

  1. Online microchannel preconcentrator for carbofuran detection.

    PubMed

    Siritham, Charinrat; Thammakhet, Chongdee; Thavarungkul, Panote; Kanatharana, Proespichaya

    2013-01-01

    A simple and rapid online microchannel preconcentrator coupled with an amperometric detection for the analysis of carbofuran using polyethylene glycol coated onto magnetic particle (PEG-magnetic particles) sorbents was developed. This simple-to-prepare microchannel preconcentrator used an external magnet to retain the PEG-magnetic particle sorbents inside the microchannel. Under optimum conditions, the system provided two linear ranges, from 0.01 to 10.0 mg L(-1) and from 10.0 to 130.0 mg L(-1) with a limit of detection of 8.7 ± 0.1 μg L(-1). The microchannel preconcentrator provided very good stability; it can be used for up to 326 consecutive injections of 5.0 mg L(-1) carbofuran with a relative standard deviation of less than 3%. The developed system provided a good microchannel-to-microchannel and a good electrode-to-electrode reproducibility (n = 6, %RSD < 1). It also provided an excellent selectivity when it was tested with two other carbamate pesticides, carbaryl and methomyl, with a 43 and 256 times higher detection sensitivity for carbofuran, respectively. The developed system was successfully applied to detect carbofuran in surface water samples obtained near vegetable plantation areas. The concentrations of carbofuran in these samples were found to be in the range of non-detectable to 0.047 ± 0.001 mg L(-1). The developed system is easy to operate and easy to couple with other analytical instruments and it could be easily adapted for the analysis of other polar organic contaminants.

  2. Analysis of opioid peptides by on-line SPE-CE-ESI-MS.

    PubMed

    Hernández, Elena; Benavente, Fernando; Sanz-Nebot, Victoria; Barbosa, José

    2007-11-01

    In this study, SPE-CE-ESI-MS is explored for the preconcentration and separation of dilute solutions of six opioid peptides. First, a CE-ESI-MS methodology was developed and validated. LODs of around 1 microg/mL were obtained for all the studied peptides. For SPE-CE-ESI-MS experiments, a home-made SPE microcartridge containing a C18 sorbent was constructed near the inlet of the separation capillary. After optimizing the on-line preconcentration methodology, LODs between 10 and 0.1 ng/mL were achieved. Repeatability, reproducibility, durability of the microcartridges and linearity of the SPE-CE-ESI-MS methodology were also investigated and compared to the values obtained by CE-ESI-MS. Finally, human plasma samples fortified with opioid peptides were analyzed by SPE-CE-ESI-MS in order to show the potential of the methodology for the analysis of biological fluids.

  3. Selective preconcentration of chemical warfare agent degradation products using a zirconia preconcentration column.

    PubMed

    Zhou, Ting; Lucy, Charles A

    2008-12-05

    Zirconia (ZrO(2)) has strong Lewis acid sites which have an affinity for the strongly electronegative phosphonate group of organo-phosphates. To investigate whether this affinity can be used for selective preconcentration, the retention of methyl, ethyl, and propylphosphonic acid (MPA, EPA and PPA) and inorganic anion matrix components on ZrO(2) was investigated. Only organo-phosphates and sulfate exhibited retention on zirconia. After preconcentration, the retained species were eluted from ZrO(2) by 0.75 mM Na(2)CO(3), and separated by a Dionex Ionpac AS11 anion-exchange column (250 mm x 2 mm I.D.) and a Hypercarb RPLC column (50 mm x 4.6 mm I.D., 3 microm) in series followed by suppressed conductivity detection. Calibration curve showed a linear response for MPA, EPA and PPA in the range of 0.01 microM to 1 microM (R(2)>0.9989). Detection limits after preconcentration of a 10 mL sample were 0.16, 0.19 and 0.16 microg/L for MPA, EPA, and PPA, respectively.

  4. Nanoporous-carbon films for microsensor preconcentrators

    NASA Astrophysics Data System (ADS)

    Siegal, M. P.; Overmyer, D. L.; Kottenstette, R. J.; Tallant, D. R.; Yelton, W. G.

    2002-05-01

    Nanoporous-carbon (NPC) films are grown using physical processes such as low-power pulsed-laser deposition with attenuation of the ablated carbon species kinetic energy attained by using an inert background gas. With room-temperature growth and negligible residual stress, NPC can coat nearly any substrate to any desired thickness. Control of the deposition energetics yields precise morphology, density, and hence, porosity, with no discernable variation in chemical bonding. We produce NPC films 8 μm thick with density <0.2 g/cm3. The well-controlled porosity, i.e., available surface area, is demonstrated by using films with different thicknesses as a preconcentrator for a nerve-gas simulant.

  5. High-throughput liquid-absorption preconcentrator sampling methods

    DOEpatents

    Zaromb, Solomon

    1994-01-01

    A system for detecting trace concentrations of an analyte in air includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container comprising a wettable material. The wettable material is continuously wetted with an analyte-sorbing liquid which flows from one part of the container to a lower end. Sampled air flows through the container in contact with the wetted material with a swirling motion which results in efficient transfer of analyte vapors or aerosol particles to the sorbing liquid and preconcentration of traces of analyte in the liquid. The preconcentrated traces of analyte may be either detected within the container or removed therefrom for injection into a separate detection means or for subsequent analysis.

  6. Online Preconcentration and Determination of Trace Amounts of Zinc in Nature Waters

    PubMed Central

    Wei, Liang; Zhang, Xinshen; Dai, Yichun; Huang, Jin; Xie, Yong-hong; Xiao, Kai

    2008-01-01

    A simple, sensitive, reliable and flexible flow injection spectrophotometric method is proposed for on-line preconcentration and determination of trace amounts of zinc in water. At the presence of Tween-80 in pH 9.3 buffer solutions, the shade of color of Zn (II)-PAN complex is in a linear relation to the zinc amount at the point of the maximum absorption peak of 560 nm. The optimal experimental conditions, including reaction conditions and preconcentration conditions, had been obtained. The linear range of the proposed method was between 2.0 and 360 μg L−1 and the detection limit was 0.42 μg L−1. The relative standard deviation was 3.55% and 2.14% for 5.0 μg L−1 and 50 μg L−1 of zinc standard solution (n = 8). The method had been successfully applied to zinc determination in water samples and the analytical results were satisfactory. PMID:18389074

  7. On-Line Communications Devices.

    ERIC Educational Resources Information Center

    Sternick, Barbara R.

    These summaries have been compiled to assist users in selecting terminals for use with the National Library of Medicine (NLM) on-line systems. The summaries describe the salient characteristics and approximate prices of a large number of hard copy and display devices. Many of the terminals listed may be modified by the addition of various options…

  8. Determination of some rare earth elements in seawater by inductively coupled plasma mass spectrometry using flow injection preconcentration

    NASA Astrophysics Data System (ADS)

    Vicente, O.; Padró, A.; Martinez, L.; Olsina, R.; Marchevsky, E.

    1998-08-01

    An on-line Eu, Tb, Ho, Tm and Lu preconcentration and determination system implemented with inductively coupled plasma mass spectrometry (ICP-MS) associated to a flow injection (FI) method was studied. Quinolin-8-ol and Amberlite XAD-7 were used for the retention of Eu, Tb, Ho, Tm and Lu, at pH 10.0. The rare earth elements were re-extracted from the microcolumn with nitric acid. The values of detection limits (DL) obtained for the preconcentration of 100 ml of aqueous solution of Eu, Tb, Ho, Tm and Lu were 0.016, 0.0023, 0.0017, 0.0035 and 0.0015 pg ml -1, respectively, with a relative standard deviation (RSD) of about 2.0%. The calibration graphs obtained by using the preconcentration system for Eu, Tb, Ho, Tm and Lu were linear at levels near the detection limits up to at least 1 ng ml -1. The method was succesfully applied to the determination of Eu, Tb, Ho, Tm and Lu in seawater samples.

  9. Evaluation of chelation preconcentration for the determination of actinide elements by flow injection ICP-MS

    SciTech Connect

    Evans, E.H.; Truscott, J.B.; Bromley, L.; Jones, P.; Turner, J.; Fairman, B.E.

    1998-12-31

    A chelation column preconcentration method has been developed for the determination of uranium and thorium in waters by ICP-MS. Detection limits of 24 pg and 60 pg respectively were obtained, but these were blank limited. Uranium and Thorium were determined in certified reference materials. Results for uranium were 121 {+-} 21 and 15 {+-} 3 ng/g in NIST 1566a and NIST 1575 compared with certified values of 132 {+-} 12 and 20 {+-} 4 ng/g respectively. Results for thorium were 29 {+-} 8 and 28 {+-} 5 ng/g in NIST 1566a and NIST 1575 compared with indicative and certified values of 40 and 37 {+-} 3 ng/g respectively. The on-line separation of actinide radionuclides was achieved by selective elution of U, Th, Pu, Np, and Am.

  10. Economic evaluation of preconcentration in production of ethanol from dilute sugar solutions.

    PubMed

    Zacchi, G; Axelsson, A

    1989-06-20

    The economic feasibility of preconcentrating dilute sugar solutions prior to fermentation is investigated. Two methods, evaporation and reverse osmosis, are compared. A computer program to determine the optimal preconcentration conditions for glucose solutions of 1.5-16 wt% has been developed. It was used to compute the fractional cost for labor and maintenance, preconcentration, fermentation, and distillation. Preconcentration with evaporation resulted in a higher total cost, compared with no preconcentration, for all cases studied, although a six-effect unit was used. Reverse osmosis was found to be economically feasible for preconcentration to about 5-10 wt % depending on the concentration of the feed.

  11. Optimization of the preconcentration system of cadmium with 1(2-thiazolylazo)-p-cresol using a knotted reactor and flame atomic absorption spectrometric detection.

    PubMed

    Cerutti, S; Ferreira, S L C; Gásquez, J A; Olsina, R A; Martinez, L D

    2004-08-30

    The present paper proposes an on-line preconcentration procedure for cadmium determination in drinking water samples. It is based on the precipitation of cadmium(II) ions on a knotted reactor (KR) using 1(2-thiazolylazo)-p-cresol (TAC) as complexing reagent. The optimization step was performed using a full factorial design involving the variables: pH, eluent concentration (nitric acid) and TAC concentration. The results of this experiment demonstrated that these variables at chosen levels are not statistically significant. Under optimized experimental established conditions, analytical parameters for the preconcentration method were: a detection limit of 40.0 ng/l, precision as relative standard deviation (RSD) of 1.2 and 1.0%, for cadmium concentration of 2.5 and 20.0 microg/l, respectively. The preconcentration factor considering the slopes of the analytical curves with and without preconcentration is 23 for a sample volume of 10 ml. This system shows a sampling frequency of 25 h(-1). In order to check the accuracy, the standard reference material, NIST SRM 1643d trace elements in water was analyzed. A comparison, using t-test demonstrates that there is not significant difference among the achieved results with proposed method and the certified values. The addition/recovery experiments in the samples analyzed demonstrated the accuracy and applicability of the system developed for cadmium determination in water samples.

  12. Preconcentration procedures for phthalate esters combined with chromatographic analysis.

    PubMed

    Lv, Xueju; Hao, Yi; Jia, Qiong

    2013-08-01

    Phthalate esters are endocrine disrupters or mutagens. They are widely used as plasticizers and can be usually found in environmental samples, such as food, soil and polluted air. However, it is difficult to directly determine phthalate esters owing to their relatively low concentration and complex matrices. Therefore, preconcentration and separation have become increasingly important. In recent years, many preconcentration methods have been successfully developed and widely used, such as liquid-liquid extraction, dispersive liquid-liquid microextraction and solid-phase extraction. These preconcentration methods for phthalate esters can be applied to various real samples, water, soil, air, food and cosmetics. The aim of this paper is to review recent literature studies (primarily from the last five years) about preconcentration techniques for phthalate esters coupled with chromatographic analysis. The following text describes several preconcentration approaches, including liquid-liquid extraction, dispersive liquid-liquid microextraction, cloud point extraction, solid-phase extraction, solid-phase microextraction and stir bar sorptive extraction. Their advantages and disadvantages are also summarized.

  13. Pressure-assisted selective preconcentration in a straight nanochannel.

    PubMed

    Louër, Anne-Claire; Plecis, Adrien; Pallandre, Antoine; Galas, Jean-Christophe; Estevez-Torres, André; Haghiri-Gosnet, Anne-Marie

    2013-08-20

    We investigate the preconcentration profiles of a fluorescein and bovine serum albumin derivatized with this fluorescent tag in a microfluidic chip bearing a nanoslit. A new preconcentration method in which a hydrodynamic pressure is added to both electroosmotic and electrophoretic contributions is proposed to monitor the location of the preconcentration frontline. A simple predictive model of this pressure-assisted electropreconcentration is proposed for the evolution of the flow profile along this micro/nano/microfluidic structure. We show with a small analyte such as fluorescein that the additional hydrostatic pressure mode enables to stabilize the concentration polarization (CP) effect, resulting in better control of the cathodic focusing (CF) peak. For BSA (bovine serum albumin), we exhibit that the variation of the hydrodynamic pressure can have an even more drastic effect on the preconcentration. We show that, depending on this hydrodynamic pressure, the preconcentration can be chosen, either in the cathodic side or in the anodic one. For the first time, we prove here that both anodic focusing (AF) and cathodic focusing (CF) regimes can be reached in the same structures. These results also open new routes for the detection and the quantification of low abundance biomarkers.

  14. On-line nuclear orientation

    SciTech Connect

    Krane, K.S.

    1990-01-01

    This grant has as its overall goal the pursuit of on-line nuclear orientation experiments for the purpose of eliciting details of nuclear structure from the decays of neutron-deficient nuclei, such as those produced by the Holifield Heavy-Ion Research Facility at Oak Ridge and extracted by the UNISOR Isotope Separator. This paper discusses: refrigerator development; the decay of {sup 184}Au; the decay of {sup 191}Hg to {sup 191}Au; the decay of {sup 189}Pt to {sup 189}Ir; the decays of {sup 109,111}Pd; the decay of {sup 172}Er; and solid angle corrections.

  15. Battery operated preconcentration-assisted lateral flow assay.

    PubMed

    Kim, Cheonjung; Yoo, Yong Kyoung; Han, Sung Il; Lee, Junwoo; Lee, Dohwan; Lee, Kyungjae; Hwang, Kyo Seon; Lee, Kyu Hyoung; Chung, Seok; Lee, Jeong Hoon

    2017-07-11

    Paper-based analytical devices (e.g. lateral flow assays) are highly advantageous as portable diagnostic systems owing to their low costs and ease of use. Because of their low sensitivity and detection limits for biomolecules, these devices have several limitations in applications for real-field diagnosis. Here, we demonstrate a paper-based preconcentration enhanced lateral flow assay using a commercial β-hCG-based test. Utilizing a simple 9 V battery operation with a low power consumption of approximately 81 μW, we acquire a 25-fold preconcentration factor, demonstrating a clear sensitivity enhancement in the colorimetric lateral flow assay; consequently, clear colors are observed in a rapid kit test line, which cannot be monitored without preconcentration. This device can also facilitate a semi-quantitative platform using the saturation value and/or color intensity in both paper-based colorimetric assays and smartphone-based diagnostics.

  16. Two-stage preconcentrator for vapor/particle detection

    DOEpatents

    Linker, Kevin L.; Brusseau, Charles A.

    2002-01-01

    A device for concentrating particles from a high volume gas stream and delivering the particles for detection in a low volume gas stream includes first and second preconcentrators. The first preconcentrator has a first structure for retaining particles in a first gas flow path through which a first gas flows at a relatively high volume, valves for selectively stopping the first gas flow; and a second gas flow path through which gas flows at an intermediate flow volume for moving particles from the first structure. The second preconcentrator includes a second structure for retaining particles in the second gas flow path; a valve for selectively stopping the second gas flow; and a third gas flow path through which gas flows at a low volume for moving particles from the second structure to a detector. Each of the particle retaining structures is preferably a metal screen that may be resistively heated by application of an electric potential to release the particles.

  17. PHENIX on-line systems

    NASA Astrophysics Data System (ADS)

    Adler, S. S.; Allen, M.; Alley, G.; Amirikas, R.; Arai, Y.; Awes, T. C.; Barish, K. N.; Barta, F.; Batsouli, S.; Belikov, S.; Bennett, M. J.; Bobrek, M.; Boissevain, J. G.; Boose, S.; Britton, C.; Britton, L.; Bryan, W. L.; Cafferty, M. M.; Carey, T. A.; Chang, W. C.; Chi, C. Y.; Chiu, M.; Cianciolo, V.; Cole, B. A.; Constantin, P.; Cook, K. C.; Cunitz, H.; Desmond, E. J.; Ebisu, K.; Efremenko, Y. V.; El Chenawi, K.; Emery, M. S.; Engo, D.; Ericson, N.; Fields, D. E.; Frank, S.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fried, J.; Gannon, J.; Gee, T. F.; Gentry, R.; Giannotti, P.; Gustafsson, H.-A.; Haggerty, J. S.; Hahn, S.; Halliwell, J.; Hamagaki, H.; Hansen, A. G.; Hara, H.; Harder, J.; He, X.; Heistermann, F.; Hemmick, T. K.; Hibino, M.; Hill, J. C.; Homma, K.; Jacak, B. V.; Jagadish, U.; Jia, J.; Kajihara, F.; Kametani, S.; Kamyshkov, Y.; Kandasamy, A.; Kang, J. H.; Kapustinsky, J.; Katou, K.; Kelley, M. A.; Kelly, S.; Kikuchi, J.; Kim, S. Y.; Kim, Y. G.; Kistenev, E.; Kotchetkov, D.; Kurita, K.; Lajoie, J. G.; Lenz, M.; Lenz, W.; Li, X. H.; Lin, S.; Liu, M. X.; Markacs, S.; Matathias, F.; Matsumoto, T.; Mead, J.; Mischke, R. E.; Mishra, G. C.; Moore, A.; Muniruzzamann, M.; Musrock, M.; Nagle, J. L.; Nandi, B. K.; Newby, J.; Nystrand, J.; O'Brien, E.; O'Connor, P.; Ohnishi, H.; Oskarsson, A.; Osterman, L.; Oyama, K.; Paffrath, L.; Pancake, C. E.; Pantuev, V. S.; Petridis, A. N.; Pisani, R. P.; Plagge, T.; Plasil, F.; Purschke, M. L.; Rankowitz, S.; Rao, R.; Rau, M.; Read, K. F.; Ryu, S. S.; Sakaguchi, T.; Sato, H. D.; Seto, R.; Shiina, T.; Silvermyr, D.; Simon-Gillo, J.; Simpson, M.; Sippach, W.; Skank, H. D.; Skutnik, S.; Sleege, G. A.; Smith, G. D.; Smith, M.; Stankus, P. W.; Steinberg, P.; Sugitate, T.; Sullivan, J. P.; Taketani, A.; Tamai, M.; Tanaka, Y.; Thomas, W. D.; Todd, R.; Toldo, F.; Turner, G.; Ushiroda, T.; Velkovska, J.; van Hecke, H. W.; Van Lith, M.; Villatte, L.; Von Achen, W.; Walker, J. W.; Wang, H. Q.; White, S. N.; Wintenberg, A. L.; Witzig, C.; Wood, L.; Xie, W.; Young, G. R.; Zajc, W. A.; Zhang, C.; Zhang, L.; PHEN. I. X. Collaboration

    2003-03-01

    The PHENIX On-Line system takes signals from the Front End Modules (FEM) on each detector subsystem for the purpose of generating events for physics analysis. Processing of event data begins when the Data Collection Modules (DCM) receive data via fiber-optic links from the FEMs. The DCMs format and zero suppress the data and generate data packets. These packets go to the Event Builders (EvB) that assemble the events in final form. The Level-1 trigger (LVL1) generates a decision for each beam crossing and eliminates uninteresting events. The FEMs carry out all detector processing of the data so that it is delivered to the DCMs using a standard format. The FEMs also provide buffering for LVL1 trigger processing and DCM data collection. This is carried out using an architecture that is pipelined and deadtimeless. All of this is controlled by the Master Timing System (MTS) that distributes the RHIC clocks. A Level-2 trigger (LVL2) gives additional discrimination. A description of the components and operation of the PHENIX On-Line system is given and the solution to a number of electronic infrastructure problems are discussed.

  18. Less common applications of monoliths: Preconcentration andsolid-phase extraction

    SciTech Connect

    Svec, Frantisek

    2006-03-27

    Monolithic materials are finding their place in a variety of fields. While liquid chromatography is the most emphasized use of this new category of porous media, some other just as important applications are eclipsed by the success of monolithic columns. This review article describes all current facets of use of monoliths in preconcentration and solid-phase extraction. In addition to the typical off line use that does not seem to be the main stream application for the monolithic materials, in-line connection of the preconcentration with HPLC, electrochromatography, electrophoresis, enzymatic digestion, as well as its applications in microfluidics are presented.

  19. Solvent vapors controlled by pre-concentration, incineration

    SciTech Connect

    Sundberg, R.E.

    1996-01-01

    Concentration of solvent vapors in ventilation air exhausted from the workplace often is too dilute for efficient destruction or recovery. Several techniques are being developed to pre-concentrate the vapors before treating them in a catalytic incinerator. Molnbacka Industri AB (Forshaga, Sweden) has developed a system to control volatile organic compound emissions by using activated carbon adsorbers to pre-concentrate the solvent vapors. The technology uses carbon adsorption and desorption to concentrate dilute solvent vapors to a much smaller air stream for efficient destruction in a catalytic incinerator.

  20. On-line surfactant monitoring

    SciTech Connect

    Mullen, K.I.; Neal, E.E.; Soran, P.D.; Smith, B.

    1995-04-01

    This group has developed a process to extract metal ions from dilute aqueous solutions. The process uses water soluble polymers to complex metal ions. The metal/polymer complex is concentrated by ultrafiltration and the metals are recovered by a pH adjustment that frees the metal ions. The metal ions pass through the ultrafiltration membrane and are recovered in a concentrated form suitable for reuse. Surfactants are present in one of the target waste streams. Surfactants foul the costly ultrafiltration membranes. It was necessary to remove the surfactants before processing the waste stream. This paper discusses an on-line device the authors fabricated to monitor the process stream to assure that all the surfactant had been removed. The device is inexpensive and sensitive to very low levels of surfactants.

  1. Instrumentation Manuals On-Line

    NASA Astrophysics Data System (ADS)

    Bryson, E.

    This database will serve as an international clearing house for observatory manuals and information on how to access them. At present, CFHT, STScI, and IRTF are participating in this project. It is the author's intention that each observatory will submit electronically a pre-formatted template which is now available on NCSA Mosaic (URL http://www.cfht.hawaii.edu/html/obs-manuals.html). The template describes the instrumentation manual in the following manner: location, version, revision, institution, description wavelength region, field, keywords, contact person, size of document, figures, tables and availability. In addition the template provides the user with a direct link to the manual if it is on-line. The project author will contact the individual or institution in charge of the template at six month intervals in order to insure the manual's accuracy. It is hoped the availability of this service will encourage all observatories to make information about their manuals available electronically.

  2. Continuous cleanup/preconcentration procedure of hydroxyvitamin D3 metabolites in plasma as an alternative to batch solid-phase extraction.

    PubMed

    Ortiz-Boyer, F; Fernández-Romero, J M; Luque de Castro, M D; Quesada, J M

    1997-08-15

    A continuous automatable cleanup procedure coupled on-line with a liquid chromatograph and UV detector for hydroxyvitamin D3 metabolites [24,25-(OH)2, 1,25-(OH)2 and 25-(OH)] as an alternative to batch solid-phase extraction is reported. The method, based on continuous solid-phase cleanup/preconcentration of the analytes, requires only the passage of the sample through a single minicolumn, which also results in a preconcentration effect which increases the sensitivity. The proposed method is also compared with a conventional batch, two-step solid-phase extraction method previously improved by the authors. The method has been checked by applying it to plasma samples spiked with the target analytes (linear range between 0.05 and 100 ng/ml with coefficient of variation values lower than 6.5%) and acceptable recoveries ranging between 94.6 and 101% have been obtained. The sampling frequency was 4 h-1.

  3. SELF-ASSEMBLY CARBON NANOTUBES IN A MICROTRAP FOR ON-LINE PRECONCENTRATION OF VOLATILE ORGANICS. (R830901)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  4. SELF-ASSEMBLY CARBON NANOTUBES IN A MICROTRAP FOR ON-LINE PRECONCENTRATION OF VOLATILE ORGANICS. (R830901)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  5. Gold volatile species atomization and preconcentration in quartz devices for atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Arslan, Yasin; Musil, Stanislav; Matoušek, Tomáš; Kratzer, Jan; Dědina, Jiří

    2015-01-01

    The on-line atomization of gold volatile species was studied and the results were compared with thermodynamic calculations in several quartz atomizers, namely: diffusion flame, flame-in-gas-shield, flame-in-plain-tube, externally heated T-tube and externally heated flame-in-T-tube. Atomization mechanism in the explored devices is proposed, where volatile species are converted to thermodynamically stable AuH at elevated temperature over 500 °C and then atomized by an interaction with a cloud of hydrogen radicals. Because of its inherent simplicity and robustness, diffusion flame was employed as a reference atomizer. It yielded atomization efficiency of 70 to 100% and a very good long time reproducibility of peak area sensitivity: 1.6 to 1.8 s μg- 1. Six and eleven times higher sensitivity, respectively, was provided by atomizers with longer light paths in the observation volume, i.e. externally heated T-tube and externally heated flame-in-T-tube. The latter one, offering limit of detection below 0.01 μg ml- 1, appeared as the most prospective for on-line atomization. Insight into the mechanism of atomization of gold volatile species, into the fate of free atoms and into subsequent analyte transfer allowed to assess possibilities of in-atomizer preconcentration of gold volatile species: it is unfeasible with quartz atomizers but a sapphire tube atomizer could be useful in this respect.

  6. The NSINIC on-line system

    NASA Technical Reports Server (NTRS)

    Lev, Brian

    1991-01-01

    The NSI NIC on-line system is described in the form of view graphs. The following subject areas are covered: NSI history; the ADFTO's other on-line services; the current system; and the next generation of NSI NIC.

  7. Zinc oxide nanorods functionalized paper for protein preconcentration in biodiagnostics

    NASA Astrophysics Data System (ADS)

    Tiwari, Sadhana; Vinchurkar, Madhuri; Rao, V. Ramgopal; Garnier, Gil

    2017-03-01

    Distinguishing a specific biomarker from a biofluid sample containing a large variety of proteins often requires the selective preconcentration of that particular biomarker to a detectable level for analysis. Low-cost, paper-based device is an emerging opportunity in diagnostics. In the present study, we report a novel Zinc oxide nanorods functionalized paper platform for the preconcentration of Myoglobin, a cardiac biomarker. Zinc oxide nanorods were grown on a Whatman filter paper no. 1 via the standard hydrothermal route. The growth of Zinc oxide nanorods on paper was confirmed by a combination of techniques consisting of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS,) scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) analysis. The Zinc oxide nanorods modified Whatman filter paper (ZnO-NRs/WFP) was further tested for use as a protein preconcentrator. Paper-based ELISA was performed for determination of pre-concentration of cardiac marker protein Myoglobin using the new ZnO-NRs/WFP platform. The ZnO-NRs/WFP could efficiently capture the biomarker even from a very dilute solution (Myoglobin < 50 nM). Our ELISA results show a threefold enhancement in protein capture with ZnO-NRs/WFP compared to unmodified Whatman filter paper, allowing accurate protein analysis and showing the diagnostic concept.

  8. Sample extraction and injection with a microscale preconcentrator.

    SciTech Connect

    Robinson, Alex Lockwood; Chan, Helena Kai Lun

    2007-09-01

    This report details the development of a microfabricated preconcentrator that functions as a fully integrated chemical extractor-injector for a microscale gas chromatograph (GC). The device enables parts-per-billion detection and quantitative analysis of volatile organic compounds (VOCs) in indoor air with size and power advantages over macro-scale systems. The 44 mm{sup 3} preconcentrator extracts VOCs using highly adsorptive, granular forms of graphitized carbon black and carbon molecular sieves. The micron-sized silicon cavities have integrated heating and temperature sensing allowing low power, yet rapid heating to thermally desorb the collected VOCs (GC injection). The keys to device construction are a new adsorbent-solvent filling technique and solvent-tolerant wafer-level silicon-gold eutectic bonding technology. The product is the first granular adsorbent preconcentrator integrated at the wafer level. Other advantages include exhaustive VOC extraction and injection peak widths an order of magnitude narrower than predecessor prototypes. A mass transfer model, the first for any microscale preconcentrator, is developed to describe both adsorption and desorption behaviors. The physically intuitive model uses implicit and explicit finite differences to numerically solve the required partial differential equations. The model is applied to the adsorption and desorption of decane at various concentrations to extract Langmuir adsorption isotherm parameters from effluent curve measurements where properties are unknown a priori.

  9. Zinc oxide nanorods functionalized paper for protein preconcentration in biodiagnostics

    PubMed Central

    Tiwari, Sadhana; Vinchurkar, Madhuri; Rao, V. Ramgopal; Garnier, Gil

    2017-01-01

    Distinguishing a specific biomarker from a biofluid sample containing a large variety of proteins often requires the selective preconcentration of that particular biomarker to a detectable level for analysis. Low-cost, paper-based device is an emerging opportunity in diagnostics. In the present study, we report a novel Zinc oxide nanorods functionalized paper platform for the preconcentration of Myoglobin, a cardiac biomarker. Zinc oxide nanorods were grown on a Whatman filter paper no. 1 via the standard hydrothermal route. The growth of Zinc oxide nanorods on paper was confirmed by a combination of techniques consisting of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS,) scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) analysis. The Zinc oxide nanorods modified Whatman filter paper (ZnO-NRs/WFP) was further tested for use as a protein preconcentrator. Paper-based ELISA was performed for determination of pre-concentration of cardiac marker protein Myoglobin using the new ZnO-NRs/WFP platform. The ZnO-NRs/WFP could efficiently capture the biomarker even from a very dilute solution (Myoglobin < 50 nM). Our ELISA results show a threefold enhancement in protein capture with ZnO-NRs/WFP compared to unmodified Whatman filter paper, allowing accurate protein analysis and showing the diagnostic concept. PMID:28252113

  10. Zinc oxide nanorods functionalized paper for protein preconcentration in biodiagnostics.

    PubMed

    Tiwari, Sadhana; Vinchurkar, Madhuri; Rao, V Ramgopal; Garnier, Gil

    2017-03-02

    Distinguishing a specific biomarker from a biofluid sample containing a large variety of proteins often requires the selective preconcentration of that particular biomarker to a detectable level for analysis. Low-cost, paper-based device is an emerging opportunity in diagnostics. In the present study, we report a novel Zinc oxide nanorods functionalized paper platform for the preconcentration of Myoglobin, a cardiac biomarker. Zinc oxide nanorods were grown on a Whatman filter paper no. 1 via the standard hydrothermal route. The growth of Zinc oxide nanorods on paper was confirmed by a combination of techniques consisting of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS,) scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) analysis. The Zinc oxide nanorods modified Whatman filter paper (ZnO-NRs/WFP) was further tested for use as a protein preconcentrator. Paper-based ELISA was performed for determination of pre-concentration of cardiac marker protein Myoglobin using the new ZnO-NRs/WFP platform. The ZnO-NRs/WFP could efficiently capture the biomarker even from a very dilute solution (Myoglobin < 50 nM). Our ELISA results show a threefold enhancement in protein capture with ZnO-NRs/WFP compared to unmodified Whatman filter paper, allowing accurate protein analysis and showing the diagnostic concept.

  11. TEST AND EVALUATION OF A POLYMER MEMBRANE PRECONCENTRATOR

    EPA Science Inventory

    The report gives results of an evaluation of the applicability of membrane systems as a preconcentrator and defines operating parameters of a membrane system. Advantages of such a system is a potential reduction in cost for subsequent control systems. The evaluation is part of a ...

  12. TEST AND EVALUATION OF A POLYMER MEMBRANE PRECONCENTRATOR

    EPA Science Inventory

    The report gives results of an evaluation of the applicability of membrane systems as a preconcentrator and defines operating parameters of a membrane system. Advantages of such a system is a potential reduction in cost for subsequent control systems. The evaluation is part of a ...

  13. Method for preconcentrating a sample for subsequent analysis

    DOEpatents

    Zaromb, Solomon

    1990-01-01

    A system for analysis of trace concentration of contaminants in air includes a portable liquid chromatograph and a preconcentrator for the contaminants to be analyzed. The preconcentrator includes a sample bag having an inlet valve and an outlet valve for collecting an air sample. When the sample is collected the sample bag is connected in series with a sorbing apparatus in a recirculation loop. The sorbing apparatus has an inner gas-permeable container containing a sorbent material and an outer gas-impermeable container. The sample is circulated through the outer container and around the inner container for trapping and preconcentrating the contaminants in the sorbent material. The sorbent material may be a liquid having the same composition as the mobile phase of the chromatograph for direct injection thereinto. Alternatively, the sorbent material may be a porous, solid body, to which mobile phase liquid is added after preconcentration of the contaminants for dissolving the contaminants, the liquid solution then being withdrawn for injection into the chromatograph.

  14. Online preconcentration using monoliths in electrochromatography capillary format and microchips.

    PubMed

    Augustin, Violaine; Proczek, Gaëlle; Dugay, José; Descroix, Stéphanie; Hennion, Marie-Claire

    2007-11-01

    Online preconcentration and separation of analytes using an in situ photopolymerized hexyl acrylate-based monolith stationary phase was evaluated using electrochromatography in capillary format and microchip. The band broadening occurring during the preconcentration process by frontal electrochromatography and during the desorption process by elution electrochromatography was studied. The hexyl acrylate-based monolith provides high retention for neutral analytes allowing the handling of large sample volumes and its structure allows rapid mass transfer, thus reducing the band broadening. For moderately polar analytes such as mono-chlorophenols that are slightly retained in water, it was shown that enrichment factors up to 3500 can be obtained by a hydrodynamic injection of several bed volumes for 120 min under 0.8 MPa with a decrease in efficiency of 50% and a decrease of 30% for the resolution between 2- and 3-chlorophenol. An 8 min preconcentration time allows enrichment factors above 100 for polyaromatic hydrocarbons. The interest of these monoliths when synthesized in microchip is also demonstrated. A 200-fold enrichment was easily obtained for PAHs with only 1 min as preconcentration time, without decrease in efficiency.

  15. List of On-Line Resources.

    ERIC Educational Resources Information Center

    Teachers & Writers, 1996

    1996-01-01

    Presents an annotated bibliography of 57 World Wide Web sites grouped by subjects, including language arts curricula and pedagogy, writing tools, "fun" writing tools, on-line libraries, on-line books, miscellaneous on-line collections, language arts indexes, technology planning guides, technology plan examples, censorship and copyrights,…

  16. Methylmercury in water samples at the pg/L level by online preconcentration liquid chromatography cold vapor-atomic fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Brombach, Christoph-Cornelius; Chen, Bin; Corns, Warren T.; Feldmann, Jörg; Krupp, Eva M.

    2015-03-01

    Ultra-traces of methylmercury at the sub-ppt level can be magnified in the foodweb and is of concern. In environmental monitoring a routine robust analytical method is needed to determine methylmercury in water. The development of an analytical method for ultra-trace speciation analysis of methylmercury (MeHg) in water samples is described. The approach is based on HPLC-CV-AFS with on-line preconcentration of water samples up to 200 mL, resulting in a detection limit of 40 pg/L (ppq) for MeHg, expressed as Hg. The unit consists of an optimized preconcentration column filled with a sulfur-based sorption material, on which mercury species are preconcentrated and subsequently eluted, separated and detected via HPLC-CV-AFS (high performance liquid chromatography-cold vapor atomic fluorescence spectrometry). During the method development a type of adsorbate material, the pH dependence, the sample load rate and the carry-over were investigated using breakthrough experiments. The method shows broad pH stability in the range of pH 0 to 7, without the need for buffer addition and shows limited matrix effects so that MeHg is quantitatively recovered from sewage, river and seawater directly in the acidified samples without sample preparation.

  17. Detection of Aromatic Nitro Compounds Using Preconcentrator and SPR Immunosensor

    NASA Astrophysics Data System (ADS)

    Onodera, Takeshi; Miyahara, Kazuhisa; Iwakura, Munehiro; Hayashi, Kenshi; Miura, Norio; Matsumoto, Kiyoshi; Toko, Kiyoshi

    In this study, we report the sensitive detection of aromatic nitro compounds using a surface plasmon resonance (SPR) immunosensor based on the indirect competitive method. The vapors from the substances were sampled with a preconcentrator developed here. The solutions of the sampled vapors were measured using SPR immunosensor. Three kinds of explosives such as 2,4-dinitrobenzene, 2,4-dinitrotoluene, and 2,4,6-trinitrotoluene were detected at 1 ppb. Sampling time at 1 l/min was 3 min. Total detection time was brought down to 5 min, which is relatively short for second scanning in landmine detection. Efforts are being made to integrate the SPR immunosensor and preconcentrator for rapid sensitive detection of nitro aromatic compounds under simulated field conditions.

  18. Preconcentration of germanium on mercapto-modified silica gel

    NASA Astrophysics Data System (ADS)

    Göktürk, Gamze; Delzendeh, Mehrdad; Volkan, Mürvet

    2000-07-01

    A simple method for the determination of ultra-trace amounts of germanium in natural waters has been developed. Germanium was preconcentrated using silica having mercapto functional groups, namely mercapto silica and determined by hydride generation flame atomic absorption spectrometry (HGAAS). Utilising mercapto silica, satisfactory recovery values (>95%) were obtained at natural pH, for germanate concentrations as low as 50 ng l -1. Considering the highest preconcentration factor (400-fold) obtained, the sensitivity and 3s-detection limit of mercapto silica-HGAAS system can be expressed as 3.65 ng l -1/0.0044 AU and 0.813 ng l -1, respectively. Interference effects of diverse ions were investigated for HGAAS and mercapto silica-HGAAS systems.

  19. Infrared micro-thermography of an actively heated preconcentrator device

    NASA Astrophysics Data System (ADS)

    Furstenberg, Robert; Kendziora, C. A.; Stepnowski, Stanley V.; Mott, David R.; McGill, R. Andrew

    2008-03-01

    We report infrared micro-thermography measurements and analysis of static and transient temperature maps of an actively heated micro-fabricated preconcentrator device that incorporates a dual serpentine platinum heater trace deposited on a perforated polyimide membrane and suspended over a silicon frame. The sorbent coated perforated membrane is used to collect vapors and gases that flow through the preconcentrator. After heating, a concentrated pulse of analyte is released into the detector. Due to its small thermal mass, precise thermal management of the preconcentrator is critical to its performance. The sizes of features, the semi-transparent membrane, the need to flow air through the device, and changes in surface emissivity on a micron scale present many challenges for traditional infrared micro-thermography. We report an improved experimental test-bed. The hardware incorporates a custom-designed miniature calibration oven which, in conjunction with spatial filtering and a simple calibration algorithm, allows accurate temperature maps to be obtained. The test-bed incorporates a micro-bolometer array as the infrared imager. Instrumentation design, calibration and image processing algorithms are discussed and analyzed. The procedure does not require prior knowledge of the emissivity. We show that relatively inexpensive uncooled bolometers arrays can be used in certain radiometric applications. Heating profiles were examined with both uniform and non-uniform air flow through the device. The conclusions from this study provide critical information for optimal integration of the preconcentrator within a detection system, and in the design of the heater trace layout to achieve a more even temperature distribution across the device.

  20. Performance analysis of the continuous trace gas preconcentrator

    NASA Astrophysics Data System (ADS)

    Muntz, E. P.; Han, Y.-L.

    2011-03-01

    In gas molecule detection systems, certain trace gas components can go undetected. This is due to ultralow yet dangerous concentrations combined with limitations of the detection methods. To remedy this problem, a preconcentrator can be included in a system to increase the trace gas concentrations, before the gas samples enter the detection unit. The widely used adsorption/desorption preconcentrators enable detection by interrupting the sampled gas flow for significant periods, in order to accumulate detectable periodic concentrations of trace gas molecules. The recently patented continuous trace gas preconcentrator (CTGP) provides a unique approach for enhancing the trace gas concentration, without stopping the flow. In this study, a performance model is developed for the CTGP, by application of the Poiseuille flow coefficients for long tubes. Based on the Cercignani-Lampis scattering kernel, Sharipov calculated the Poiseuille flow coefficients for various geometries and numerous operating Knudsen numbers. The concentrations of sampled molecules were analyzed in this study using Sharipov's flow coefficients. The results presented here reinforce the potential benefits of the CTGP.

  1. Flame AAS determination of lead in water with flow-injection preconcentration and speciation using functionalized cellulose sorbent.

    PubMed

    Naghmush, A M; Pyrzyńska, K; Trojanowicz, M

    1995-06-01

    The on-line solid phase extraction of trace amount of lead in flow-injection system with flame AAS detection was investigated using cellulose sorbents with phosphonic acid and carboxymethyl groups, C(18) sorbent non-modified and modified with Pyrocatechol Violet or 8-quinolinol, commercial chelating sorbents Chelex 100 and Spheron Oxin 1000, non-polar sorbent Amberlite XAD-2 modified with Pyrocatechol Violet and several cation-exchange resins. The best dynamic characteristics of retention were observed for functionalized cellulose sorbents. For Cellex P assumed as optimum sorbent, elution with a separate fractions of nitric acid and ethanol allows the differentiation between tetraalkyllead and sum of inorganic lead and organolead species of smaller number of alkyl groups. The detection limit for the determination of inorganic Pb(II) was estimated as 0.17 microg/l. at preconcentration from 50 ml sample at a flow rate of 7 ml/min.

  2. Determination of Ti, Zr, Nb, V, W and Mo in seawater by a new online-preconcentration method and subsequent ICP-MS analysis

    NASA Astrophysics Data System (ADS)

    Poehle, Sandra; Schmidt, Katja; Koschinsky, Andrea

    2015-04-01

    . The applicability of the on-line preconcentration method was demonstrated for samples collected during a GEOTRACES cruise in the Atlantic. Due to the low limit of quantification, LOQ, and SD, this method enables the determination of ultratrace concentration levels for Ti, Zr, Nb and W as well as the detection of small variations in concentration for all six elements. The required sample volume of only 50 mL, the fast determination within 1 h for all elements and the principle of a closed system are a clear advantage of the analytical procedure compared to many other methods and facilitates sample logistics for the determination of Ti, Zr, Nb, V, W and Mo in seawater. Online-preconcentration method for Ti, Zr, Nb, V, Mo and W in seawater. Detection of ultratrace concentrations for Ti, Zr, Nb and W in seawater. Low standard deviation of the method enables detection of small variations Mo and V. Spikes for Ti, Zr, Nb, V, Mo and W were recovered quantitatively in North Sea water. Quantitative recovery of V and Mo in seawater reference standard NASS-6.

  3. Flow injection on-line displacement/solid phase extraction system coupled with flame atomic absorption spectrometry for selective trace silver determination in water samples.

    PubMed

    Christou, Chrysoula K; Anthemidis, Aristidis N

    2009-04-15

    A novel flow injection (FI) on-line displacement solid phase extraction preconcentration and/or separation method coupled with FAAS in order to minimize interference from other metals was developed for trace silver determination. The proposed method involved the on-line formation and subsequently pre-sorption of lead diethyldithiocarbamate (Pb-DDTC) into a column packed with PTFE-turnings. The preconcentration and/or separation of the Ag(I) took place through a displacement reaction between Ag(I) and Pb(II) of the pre-sorbed Pb-DDTC. Finally, the retained analyte was eluted with isobutyl methyl ketone (IBMK) and delivered directly to nebulizer for measuring. Interference from co-existing ions with lower DDTC complex stability in comparison with Pb-DDTC, was eliminated without need for any masking reagent. With 120 s of preconcentration time at a sample flow rate of 7.6 mL min(-1), an enhancement factor of 110 and a detection limit (3s) of 0.2 microg L(-1) were obtained. The precision (RSD, n=10) was 3.1% at the 10 mug L(-1) level. The developed method was successfully applied to trace silver determination in a variety of environmental water samples and certified reference material.

  4. Development of a New Microextraction Fiber Combined to On-Line Sample Stacking Capillary Electrophoresis UV Detection for Acidic Drugs Determination in Real Water Samples

    PubMed Central

    Araujo, Lilia; Prieto, Avismelsi; Navalón, Alberto; Vílchez, José Luis; Valera, Paola; Zambrano, Ana; Dugas, Vincent

    2017-01-01

    A new analytical method coupling a (off-line) solid-phase microextraction with an on-line capillary electrophoresis (CE) sample enrichment technique was developed for the analysis of ketoprofen, naproxen and clofibric acid from water samples, which are known as contaminants of emerging concern in aquatic environments. New solid-phase microextraction fibers based on physical coupling of chromatographic supports onto epoxy glue coated needle were studied for the off-line preconcentration of these micropollutants. Identification and quantification of such acidic drugs were done by capillary zone electrophoresis (CZE) using ultraviolet diode array detection (DAD). Further enhancement of concentration sensitivity detection was achieved by on-line CE “acetonitrile stacking” preconcentration technique. Among the eight chromatographic supports investigated, Porapak Q sorbent showed higher extraction and preconcentration capacities. The screening of parameters that influence the microextraction process was carried out using a two-level fractional factorial. Optimization of the most relevant parameters was then done through a surface response three-factor Box-Behnken design. The limits of detection and limits of quantification for the three drugs ranged between 0.96 and 1.27 µg∙L−1 and 2.91 and 3.86 µg∙L−1, respectively. Recovery yields of approximately 95 to 104% were measured. The developed method is simple, precise, accurate, and allows quantification of residues of these micropollutants in Genil River water samples using inexpensive fibers. PMID:28686186

  5. On-Line Assessment: What, Why, How.

    ERIC Educational Resources Information Center

    Natal, Dottie

    Recent increases in the speed and accessibility of computers and networks have made it possible to administer tests on-line. On-line assessment can be conducted in a controlled setting, such as a testing center, or distributed over local area networks or the Internet to libraries and student homes, allowing students the flexibility to complete…

  6. Testing Claims for On-Line Conferences.

    ERIC Educational Resources Information Center

    Selfe, Cynthia L.; Meyer, Paul R.

    1991-01-01

    Describes an exploratory study of gender and power relationships on Megabyte University, one particular on-line conference. Finds that, although results of the study are not definite, they do suggest that gender and power are present to some extent even in on-line conferences. (MG)

  7. Magnetic materials as sorbents for metal/metalloid preconcentration and/or separation. A review.

    PubMed

    Giakisikli, Georgia; Anthemidis, Aristidis N

    2013-07-30

    The use of magnetic materials in solid phase extraction has received considerable attention in recent years taking into account many advantages arising from the inherent characteristics of magnetic particles. Magnetic solid phase extraction (MSPE) methodology overcomes problems such as column packing and phase separation, which can be easily performed by applying an external magnetic field. The use of magnetic particles in automatic systems is growing over the last few years making the on-line operation of MSPE a promising technique in the frame of green chemistry. This article aims to provide all recent progress in the research of novel magnetic materials as sorbents for metal preconcentration and determination coupled with different detection systems as well as their implementation in sequential injection and microfluidic systems. In addition, a description of preparation, characterization as well as applications of various types of magnetic materials, either with organic or inorganic coating of the magnetic core, is presented. Concluding remarks and future trends are also commented. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. The use of a polymer inclusion membrane for separation and preconcentration of orthophosphate in flow analysis.

    PubMed

    Nagul, Edward A; Fontàs, Clàudia; McKelvie, Ian D; Cattrall, Robert W; Kolev, Spas D

    2013-11-25

    A highly sensitive flow analysis system has been developed for the trace determination of reactive phosphate in natural waters, which uses a polymer inclusion membrane (PIM) with Aliquat 336 as the carrier for on-line analyte separation and preconcentration. The system operates under flow injection (FI) and continuous flow (CF) conditions. Under optimal FI conditions the system is characterised by a linear concentration range between 0.5 and 1000 μg L(-1)P, a sampling rate of 10h(-1), a limit of detection of 0.5 μgL(-1)P and RSDs of 3.2% (n = 10, 100 μg L(-1)) and 7.7% (n = 10, 10 μg L(-1)). Under CF conditions with 10 min stop-flow time and sample solution flow rate of 1.32 mL min(-1) the flow system offers a limit of detection of 0.04 μg L(-1)P, a sampling rate of 5h(-1) and an RSD of 3.4% (n=5, 2.0 μg L(-1)). Interference studies revealed that anions commonly found in natural waters did not interfere when in excess of at least one order of magnitude. The flow system, operating under CF conditions, was successfully applied to the analysis of natural water samples containing concentrations of phosphate in the low μg L(-1)P range, using the multipoint standard addition method.

  9. On-line chemical composition analyzer development

    SciTech Connect

    Garrison, A.A.

    1993-01-01

    This report relates to the development of an on-line Raman analyzer for control of a distillation column. It is divided into: program issues, experimental control system evaluation, energy savings analysis, and reliability analysis. (DLC)

  10. On-line generalized Steiner problem

    SciTech Connect

    Awerbuch, B.; Azar, Y.; Bartal, Y.

    1996-12-31

    The Generalized Steiner Problem (GSP) is defined as follows. We are given a graph with non-negative weights and a set of pairs of vertices. The algorithm has to construct minimum weight subgraph such that the two nodes of each pair are connected by a path. We consider the on-line generalized Steiner problem, in which pairs of vertices arrive on-line and are needed to be connected immediately. We give a simple O(log{sup 2} n) competitive deterministic on-line algorithm. The previous best online algorithm (by Westbrook and Yan) was O({radical}n log n) competitive. We also consider the network connectivity leasing problem which is a generalization of the GSP. Here edges of the graph can be either bought or leased for different costs. We provide simple randomized O(log{sup 2} n) competitive algorithm based on the on-line generalized Steiner problem result.

  11. Miniaturized Explosive Preconcentrator for Use in a Man-Portable Field Detection System

    SciTech Connect

    Hannum, David W.; Linker, Kevin L.; Parmeter, John E.; Rhykerd, Charles L.; Varley, Nathan R.

    1999-08-02

    We discuss the design and testing of a miniaturized explosives preconcentrator that can be used to enhance the capabilities of man-portable field detection systems, such as those based on ion mobility spectrometry (IMS). The preconcentrator is a smaller version of a similar device that was developed recently at Sandia National Laboratories for use in a trace detection portal that screens personnel for explosives. Like its predecessor, this preconcentrator is basically a filtering device that allows a small amount of explosive residue in a large incoming airflow to be concentrated into a much smaller air volume via adsorption and resorption, prior to delivery into a chemical detector. We discuss laboratory testing of this preconcentrator interfaced to a commercially available IMS-based detection system, with emphasis on the explosives 2,4,6-trinitrotoluene (TNT) and cyclotrimethylenetrinitramine (RDX). The issues investigated include optimization of the preconcentrator volume and inlet airflow, the use of different types of adsorbing surfaces within the preconcentrator, Wd preconcentrator efficiency and concentration factor. We discuss potential field applications of the preconcentrator, as well as avenues for further investigations and improvements.

  12. Microfluidic paper-based biomolecule preconcentrator based on ion concentration polarization.

    PubMed

    Han, Sung Il; Hwang, Kyo Seon; Kwak, Rhokyun; Lee, Jeong Hoon

    2016-06-21

    Microfluidic paper-based analytical devices (μPADs) for molecular detection have great potential in the field of point-of-care diagnostics. Currently, a critical problem being faced by μPADs is improving their detection sensitivity. Various preconcentration processes have been developed, but they still have complicated structures and fabrication processes to integrate into μPADs. To address this issue, we have developed a novel paper-based preconcentrator utilizing ion concentration polarization (ICP) with minimal addition on lateral-flow paper. The cation selective membrane (i.e., Nafion) is patterned on adhesive tape, and this tape is then attached to paper-based channels. When an electric field is applied across the Nafion, ICP is initiated to preconcentrate the biomolecules in the paper channel. Departing from previous paper-based preconcentrators, we maintain steady lateral fluid flow with the separated Nafion layer; as a result, fluorescent dyes and proteins (FITC-albumin and bovine serum albumin) are continuously delivered to the preconcentration zone, achieving high preconcentration performance up to 1000-fold. In addition, we demonstrate that the Nafion-patterned tape can be integrated with various geometries (multiplexed preconcentrator) and platforms (string and polymer microfluidic channel). This work would facilitate integration of various ICP devices, including preconcentrators, pH/concentration modulators, and micro mixers, with steady lateral flows in paper-based platforms.

  13. PNEUMATIC MICROVALVE FOR ELECTROKINETIC SAMPLE PRECONCENTRATION AND CAPILLARY ELECTROPHORESIS INJECTION

    SciTech Connect

    Cong, Yongzheng; Rausch, Sarah J.; Geng, Tao; Jambovane, Sachin R.; Kelly, Ryan T.

    2014-10-27

    Here we show that a closed pneumatic microvalve on a PDMS chip can serve as a semipermeable membrane under an applied potential, enabling current to pass through while blocking the passage of charged analytes. Enrichment of both anionic and cationic species has been demonstrated, and concentration factors of ~70 have been achieved in just 8 s. Once analytes are concentrated, the valve is briefly opened and the sample is hydrodynamically injected onto an integrated microchip or capillary electrophoresis (CE) column. In contrast to existing preconcentration approaches, the membrane-based method described here enables both rapid analyte concentration as well as high resolution separations.

  14. Progress in metal ion separation and preconcentration : an overview.

    SciTech Connect

    Bond, A. H.

    1998-05-19

    A brief historical perspective covering the most mature chemically-based metal ion separation methods is presented, as is a summary of the recommendations made in the 1987 National Research Council (NRC) report entitled ''Separation and Purification: Critical Needs and Opportunities''. A review of Progress in Metal Ion Separation and Preconcentration shows that advances are occurring in each area of need cited by the NRC. Following an explanation of the objectives and general organization of this book, the contents of each chapter are briefly summarized and some future research opportunities in metal ion separations are presented.

  15. Sorption preconcentration of vanadium for its determination in sea water

    SciTech Connect

    Andreeva, I.Yu.; Lebedeva, L.I.; Izotova, Yu.A.; Danilova, E.Ya.

    1987-08-10

    This work is devoted to a study of the conditions of vanadium sorption by a fibrous sorbent with a view to evolving a procedure for its determination in sea water. The sorbent was the same as used by them earlier for molybdenum preconcentration. It is a fiber based on polyethylenepolyamine-modified polyacrylonitrile. The sorbent contained 80% tertiary and approx. = 20% primary and secondary amino groups. Static exchange capacity of the sorbent relative to HCl 2 mmole/g, swelling 34%, fiber diameter 0.016 mm. The vanadium content was determined photometrically using acidic chromium blue K.

  16. Nanofluidic Pre-Concentration Devices for Enhancing the Detection Sensitivity and Selectivity of Biomarkers for Human Performance Monitoring

    DTIC Science & Technology

    2014-11-24

    aptamers to enhance specificity. Additionally, pre-concentration was coupled to various detection paradigms to achieve high-sensitivity biomarker... Aptamers , Biomarkers, Nanofluidics, Pre-concentration Devices, Sensing 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER...devices and optimized electrokinetic pre-concentration conditions for key neurological biomarkers of interest, by using nanoparticles and aptamers to

  17. 3D printed micro/nanofluidic preconcentrator for charged sample based on ion concentration polarization

    NASA Astrophysics Data System (ADS)

    Pi, Hailong; Tong, Jianhua; Bian, Chao; Xia, Shanhong

    2017-05-01

    In this paper, we introduce a novel and simple method to fabricate a preconcentrator based on the ion concentration polarization phenomenon (ICP). Using a three-dimensional printed layer, the microchannels could be easily integrated with an ion exchange membrane which plays the role of the nanoporous junction needed for ICP. To demonstrate the preconcentration ability of the devices, we conducted experiments with negatively charged fluorescein sodium and positively charged rhodamine 6G. As a result, the negatively charged sample could be preconcentrated more than 18 fold by using a cation exchange membrane. The positively charged sample could be preconcentrated more than 40 fold by using an anion exchange membrane. This preconcentrator with a simple fabrication process could be implemented in various microfluidic systems for biochemical assays.

  18. An electrodynamic preconcentrator integrated thermoelectric biosensor chip for continuous monitoring of biochemical process

    NASA Astrophysics Data System (ADS)

    Choi, Yong-Hwan; Kim, Min-gu; Kang, Dong-Hyun; Sim, Jaesam; Kim, Jongbaeg; Kim, Yong-Jun

    2012-04-01

    This paper proposes an integrated sensor chip for continuous monitoring of a biochemical process. It is composed of a preconcentrator and a thermoelectric biosensor. In the preconcentrator, the concentration of the injected biochemical sample is electrodynamically condensed. Then, in the downstream thermoelectric biosensor, the preconcentrated target molecules react with sequentially injected capture molecules and generate reaction heat. The reaction heat is detected based on the thermoelectric effect, and an integrated split-flow microchannel improves the sensor stability by providing ability to self-compensate thermal noise. These sequential preconcentration and detection processes are performed in completely label-free and continuous conditions and consequently enhance the sensor sensitivity. The performance of the integrated biosensor chip was evaluated at various flow rates and applied voltages. First, in order to verify characteristics of the fabricated preconcentrator, 10 µm -diameter polystyrene (PS) particles were used. The particles were concentrated by applying ac voltage from 0 to 16 Vpp at 3 MHz at various flow rates. In the experimental result, approximately 92.8% of concentration efficiency was achieved at a voltage over 16 Vpp and at a flow rate below 100 µl h-1. The downstream thermoelectric biosensor was characterized by measuring reaction heat of biotin-streptavidin interaction. The preconcentrated streptavidin-coated PS particles flow into the reaction chamber and react with titrated biotin. The measured output voltage was 288.2 µV at a flow rate of 100 µl h-1 without preconcentration. However, by using proposed preconcentrator, an output voltage of 812.3 µV was achieved with a 16 Vpp-applied preconcentration in the same given sample and flow rate. According to these results, the proposed label-free biomolecular preconcentration and detection technique can be applied in continuous and high-throughput biochemical applications.

  19. Separation/Preconcentration Techniques for Rare Earth Elements Analysis

    NASA Astrophysics Data System (ADS)

    Hu, Bin; He, Man; Chen, Beibei; Jiang, Zucheng

    2016-10-01

    The main aim of this chapter exactly characterizes the contribution. The analytical chemistry of the rare earth elements (REEs) very often is highly complicated and the determination of a specific element is impossible without a sample pre-concentration. Sample preparation can be carried out either by separation of the REEs from the matrix or by concentrating the REEs. The separation of REEs from each other is mainly made by chromatography. At the beginning of REE analysis, the method of precipitation/coprecipitation was applied for the treatment of REE mixtures. The method is not applicable for the separation of trace amounts of REEs. The majority of the methods used are based on the distribution of REEs in a two-phase system, a liquid-liquid or a liquid-solid system. Various techniques have been developed for the liquid-liquid extraction (LLE), in particular the liquid phase micro-extraction. The extraction is always combined with a pre-concentration of the REEs in a single drop of extractant or in a hollow fiber filled with the extractant. Further modified techniques for special applications and for difficult REE separation have been developed. Compared to the LLE, the solid phase micro-extraction is preferred. The method is robust and easy to handle, in which the solid phase loaded with the REEs can be used directly for subsequent determination methods. At present, very new solid materials, like nanotubes, are developed and tested for solid phase extraction.

  20. On-line atomic data access

    SciTech Connect

    Schultz, D.R.; Nash, J.K.

    1996-04-01

    The need for atomic data is one which continues to expand in a wide variety of applications including fusion energy, astrophysics, laser- produced plasma research, and plasma processing. Modern computer database and communications technology nables this data to be placed on-line and obtained by users of the Internet. Presented here is a summary of the observations and conclusions regarding such on-line atomic data access derived from a forum held at the Tenth APS Topical Conference on Atomic Processes in Plasmas.

  1. On-line atomic data access

    NASA Astrophysics Data System (ADS)

    Schultz, David R.; Nash, Jeffrey K.

    1996-07-01

    The need for atomic data is one which continues to expand in a wide variety of applications including fusion energy, astrophysics, laser-produced plasma research, and plasma processing. Modern computer database and communications technology enables this data to be placed on-line and obtained by users over the INTERNET. Presented here is a summary of the observations and conclusions regarding such on-line atomic data access derived from a forum held at the Tenth APS Topical Conference on Atomic Processes in Plasmas.

  2. IPAC datasets and on-line services.

    NASA Astrophysics Data System (ADS)

    Ebert, R.; Helou, G.; Mazzarella, J.; IPAC Tools Group

    The Infrared Processing and Analysis Center (IPAC) was created by NASA in 1983 to process and analyze data from the IRAS satellite. At present, IPAC on-line services are intended first to provide access to the extensive IRAS archives (catalogs, images, raw scan data) and second to support observation planning and data analysis for new IR missions, in particular ESA's Infrared Space Observatory (ISO). Here, information on access to the IPAC on-line catalogs is given and the software tools IRSKY, XCATSCAN, and XSCANPI are described in some detail.

  3. Effects of microchannel geometry on preconcentration intensity in microfluidic chips with straight or convergent-divergent microchannels.

    PubMed

    Chen, Chia-Lin; Yang, Ruey-Jen

    2012-03-01

    Preconcentration microfluidic devices are fabricated incorporating straight or convergent-divergent microchannels and hydrogel or Nafion membranes. Sample preconcentration is achieved utilizing concentration-polarization effects. The effects of the microchannel geometry on the preconcentration intensity are systematically examined. It is shown that for the preconcentrator with the straight microchannel, the time required to achieve a satisfactory preconcentration intensity increases with an increasing channel depth. For the convergent-divergent microchannel, the preconcentration intensity increases with a reducing convergent channel width. Comparing the preconcentration performance of the two different microchannel configurations, it is found that for an equivalent width of the main microchannel, the concentration effect in the convergent-divergent microchannel is faster than that in the straight microchannel.

  4. System and method for preconcentrating, identifying, and quantifying chemical and biological substances

    DOEpatents

    Yu, Conrad M.; Koo, Jackson C.

    2000-01-01

    A system and method for preconcentrating, identifying, and quantifying chemical and biological substances is disclosed. An input valve directs a first volume of a sample gas to a surface acoustic wave (SAW) device. The SAW device preconcentrates and detects a mass of a substance within the sample gas. An output valve receives a second volume of the sample gas containing the preconcentrated substance from the SAW device and directs the second volume to a gas chromatograph (GC). The GC identifies the preconcentrated substance within the sample gas. A shunt valve exhausts a volume of the sample gas equal to the first volume minus the second volume away from the SAW device and the GC. The method of the present invention includes the steps of opening an input valve for passing a first volume of a sample gas to a SAW device; preconcentrating and detecting a mass of a substance within the sample gas using the SAW device; opening an output valve for passing a second volume of the sample gas containing the preconcentrated substance to a gas chromatograph (GC); and then identifying the preconcentrated substance within the sample gas using the GC.

  5. Micro Gas Preconcentrator Made of a Film of Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Takada, Shuji; Nakai, Takashi; Thurakitseree, Theerapol; Shiomi, Junichiro; Maruyama, Shigeo; Takagi, Hideki; Shuzo, Masaki; Delaunay, Jean-Jacques; Yamada, Ichiro

    The development of micro gas preconcentrators is crucial for the realization of miniaturized gas chromatography (micro-GC) systems which are expected to open up new applications such as breath analysis. One of the major problems with the reduction in the preconcentrator size by miniaturization is the availability of a sorbent material having high enough concentration factor. Single-walled carbon nanotubes (SWNTs) are one of the promising materials for high adsorption capacity. In this report, a gas preconcentrator having a depth of 40 μm and a volume of 1 μL was microfabricated. The synthesized SWNT films with a thickness of 30 μm were embedded in the micro gas preconcentrators by using the hot water-assisted detachment method. The small size of the fabricated micro gas preconcentrator and the use of SWNTs as the adsorbent material allow for achieving a concentration factor as high as 16000 for 2 ppm octane. This concentration factor value is the highest reported to date for micro gas preconcentrators and sufficient for micro-GC detectors to concentrate trace analytes of interest for breath analysis. It is concluded that micro gas preconcentrators using SWNTs as the adsorbent material have great potential to concentrate compounds.

  6. Improvement of copper FAAS determination conditions via preconcentration procedure with the use of salicylaldoxime complex trapped in polymer matrix.

    PubMed

    Tobiasz, Anna; Walas, Stanisław; Landowska, Lucyna; Konefał-Góral, Jadwiga

    2012-07-15

    The paper presents application of a new resin dedicated to copper(II) flow-injection on-line preconcentration prior its flame atomic absorption spectrometric (FAAS) determination. The new sorbent, obtained by suspension polymerization technique, was styrene-divinylbenzene copolymer modified with 5-dodecylsalicylaldoxime-copper(II) complex. In flow mode leaching of initially imprinted Cu(II) ions from polymer beads was effective with 1% (v/v) nitric acid, however for elution of ions retained on the sorbent during the loading process sufficient efficiency was obtained for 0.5% (v/v) nitric acid. The most effective copper(II) sorption was observed within sample pH ca. 6.3 at flow rate 7.5mLmin(-1). Furthermore, preconcentration studies of Cu(II) ions realized in the presence of popular foreign ions like Cd(II), Pb(II), Zn(II), Ni(II), Mn(II), Co(II) did not reveal significant interference. The expected effect of Cu(II)-imprinting was confirmed by higher tolerance level for interferents ions concentration for the new sorbent than for the control polymer. It was found that alkaline metals ions and humic acid had the most relevant influence on copper(II) uptake. Accuracy of the evaluated method was assessed for analysis of water samples (tap and mineral water, river water, artesian water) and certified water reference materials compare them to results obtained by inductively plasma mass spectrometry. The satisfactory relative error values obtained with use of standard addition calibration method, confirms the feasibility of this method for Cu(II) determination in water samples. Application of 120s sorption time enabled to obtain 74-fold enrichment factor and limit of detection (3σ) equal to 0.4μgL(-1). Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Characterization of discontinuous buffer junctions using pH indicators in capillary electrophoresis for protein preconcentration.

    PubMed

    Jurcic, Kristina; Nesbitt, Chandra A; Yeung, Ken K-C

    2006-11-17

    An effective sample preconcentration technique for proteins and peptides was recently developed using capillary electrophoresis (CE) with discontinuous buffers [C.A. Nesbitt, J.T.-M. Lo, K.K.-C. Yeung, J. Chromatogr. A 1073 (2005) 175]. Two buffers of different pH created a junction to trap the sample molecules at their isoelectric points and resulted in over 1000-fold preconcentration for myoglobin within 30 min. To study the formation of pH junctions in CE, a pH indicator, bromothymol blue, is used in this work to reveal the pH changes at the discontinuous buffer boundary. Bromothymol blue (BTB) exhibits a drastic change in its visible absorption spectrum (300-600 nm) going from the acidic to basic pH conditions, and is therefore ideal for visualizing the changes in pH at the junctions created by various buffer combinations. Preconcentration of myoglobin was performed in discontinuous buffers containing BTB. Major differences in the BTB absorption profiles were identified from buffer systems that differ significantly in preconcentration performance, which in turn, allowed for the identification of ideal buffers for sample preconcentration. Up to 2000-fold preconcentrations of myoglobin were achieved in the buffer systems studied in this work. In addition, the role of the electroosmotic flow (EOF) on the preconcentration performance was investigated. A low EOF was found to be desirable, as the pH junction could stay longer in the capillary for accumulation of proteins. The pH junction also displayed characteristics to resist bandbroadening. Potential laminar flow resulted from the mismatched residual EOFs under the two pH conditions within the discontinuous buffers appeared to have minimal effect on the preconcentration. In fact, external applied pressure can be used to control the migration of the pH junction without compromising the protein preconcentration.

  8. [Determination of Pb and Cd in atomospheric particulates by flame atomic absorption spectrometry coupled with on-line flow injection pretreatment with ultrasonic leaching].

    PubMed

    Gao, Yan; Wang, Dong-hai; Lin, Yu-bin; Li, Jian-yi; Kong, Qing-zhen

    2003-04-01

    In this paper, the method for extracting the metals from the filter membrane of the atomospheric particulates with ultrasonic leaching was reported. The dissolution conditions of kinds and acidity as well as the interference conditions were studied. The method of determination Pb and Cd of the atomospheric particulates by flame atomic absorption spectrometry coupled with on-line flow injection preconcentration was proved to be rapid and accuracy. The recoveries are more than 97%. The relative standard deviation of six samples are less than 2.6%.

  9. On-line electroplating thickness monitor

    NASA Astrophysics Data System (ADS)

    Moore, Clifford G.

    1989-03-01

    This paper describes a novel instrumental technique for on-line measuring the thickness of electroplating, based on the precise determination of the resistance of the electroplated deposit on a stainless steel wire sensor. Laboratory and field testing of the technique is described. Data are presented for nickel, copper, and gold. Block diagrams for the sensor and the system are presented.

  10. On-Line Tutoring by Preservice Teachers.

    ERIC Educational Resources Information Center

    Smith, Gary R.; Carroll, Geraldine

    This activity involved on-line tutoring by preservice teachers for high-risk students. It was part of a Technology Literacy Challenge Fund grant from the Michigan Department of Education. The project provided iMac computers and other technology resources in 20 classrooms within four Detroit public schools. Each computer was connected to the school…

  11. LUST ON-LINE CALCULATOR INTRODUCTION

    EPA Science Inventory

    EPA has developed a suite of on-line calculators to assist in performing site assessment and modeling calculations for leaking underground storage tank sites (http://www.epa.gov/athens/onsite). The calculators are divided into four types: parameter estimation, models, scientific...

  12. LUST ON-LINE CALCULATOR INTRODUCTION

    EPA Science Inventory

    EPA has developed a suite of on-line calculators to assist in performing site assessment and modeling calculations for leaking underground storage tank sites (http://www.epa.gov/athens/onsite). The calculators are divided into four types: parameter estimation, models, scientific...

  13. Authority Issues in On-Line Instruction.

    ERIC Educational Resources Information Center

    Podis, JoAnne M.

    An informal study examined the sources of professors' authority and whether the authority dynamic between professor and student changes in an electronic setting. Five on-line writing instructors (who use Internet Email or the World Wide Web) completed a questionnaire. Results indicated that (1) professors tended, at least initially, to replicate…

  14. Transformation invariant on-line target recognition.

    PubMed

    Iftekharuddin, Khan M

    2011-06-01

    Transformation invariant automatic target recognition (ATR) has been an active research area due to its widespread applications in defense, robotics, medical imaging and geographic scene analysis. The primary goal for this paper is to obtain an on-line ATR system for targets in presence of image transformations, such as rotation, translation, scale and occlusion as well as resolution changes. We investigate biologically inspired adaptive critic design (ACD) neural network (NN) models for on-line learning of such transformations. We further exploit reinforcement learning (RL) in ACD framework to obtain transformation invariant ATR. We exploit two ACD designs, such as heuristic dynamic programming (HDP) and dual heuristic dynamic programming (DHP) to obtain transformation invariant ATR. We obtain extensive statistical evaluations of proposed on-line ATR networks using both simulated image transformations and real benchmark facial image database, UMIST, with pose variations. Our simulations show promising results for learning transformations in simulated images and authenticating out-of plane rotated face images. Comparing the two on-line ATR designs, HDP outperforms DHP in learning capability and robustness and is more tolerant to noise. The computational time involved in HDP is also less than that of DHP. On the other hand, DHP achieves a 100% success rate more frequently than HDP for individual targets, and the residual critic error in DHP is generally smaller than that of HDP. Mathematical analyses of both our RL-based on-line ATR designs are also obtained to provide a sufficient condition for asymptotic convergence in a statistical average sense.

  15. Process for separation and preconcentration of radium from water

    DOEpatents

    Dietz, M.; Horwitz, E.P.; Chiarizia, R.; Bartsch, R.A.

    1999-01-26

    A process for preconcentrating and separating radium from a contaminated solution containing at least water and radium includes the steps of adding a quantity of a water-soluble macrocyclic polyether to the contaminated solution to form a combined solution. An acid is added to the combined solution to form an acidic combined solution having an [H{sup +}] concentration of about 0.5M. The acidic combined solution is contacted with a sulfonic acid-based strong acid cation exchange medium or a organophilic sulfonic acid medium having a plurality of binding sites thereon to bind the radium thereto and to form a radium-depleted solution. The radium-depleted solution is separated from the strong acid cation exchange medium or organophilic sulfonic acid medium. The radium remaining bound to the exchange medium or organophilic reagent is then stripped from the exchange medium or organophilic medium and the activity of the radium is measured. 24 figs.

  16. Process for separation and preconcentration of radium from water

    DOEpatents

    Dietz, Mark; Horwitz, E. Philip; Chiarizia, Renato; Bartsch, Richard A.

    1999-01-01

    A process for preconcentrating and separating radium from a contaminated solution containing at least water and radium includes the steps of adding a quantity of a water-soluble macrocyclic polyether to the contaminated solution to form a combined solution. An acid is added to the combined solution to form an acidic combined solution having an ›H.sup.+ ! concentration of about 0.5M. The acidic combined solution is contacted with a sulfonic acid-based strong acid cation exchange medium or a organophilic sulfonic acid medium having a plurality of binding sites thereon to bind the radium thereto and to form a radium-depleted solution. The radium-depleted solution is separated from the strong acid cation exchange medium or organophilic sulfonic acid medium. The radium remaining bound to the exchange medium or organophilic reagent is then stripped from the exchange medium or organophilic medium and the activity of the radium is measured.

  17. Multiplexed electrokinetic sample fractionation, preconcentration and elution for proteomics.

    PubMed

    Hua, Yujuan; Jemere, Abebaw B; Dragoljic, Jelena; Harrison, D Jed

    2013-07-07

    Both 6 and 8-channel integrated microfluidic sample pretreatment devices capable of performing "in space" sample fractionation, collection, preconcentration and elution of captured analytes via sheath flow assisted electrokinetic pumping are described. Coatings and monolithic polymer beds were developed for the glass devices to provide cationic surface charge and anodal electroosmotic flow for delivery to an electrospray emitter tip. A mixed cationic ([2-(methacryloyloxy)ethyl] trimethylammonium chloride) (META) and hydrophobic butyl methacrylate-based monolithic porous polymer, photopolymerized in the 6- or 8-fractionation channels, was used to capture and preconcentrate samples. A 0.45 wt% META loaded bed generated comparable anodic electroosmotic flow to the cationic polymer PolyE-323 coated channel segments in the device. The balanced electroosmotic flow allowed stable electrokinetic sheath flow to prevent cross contamination of separated protein fractions, while reducing protein/peptide adsorption on the channel walls. Sequential elution of analytes trapped in the SPE beds revealed that the monolithic columns could be efficiently used to provide sheath flow during elution of analytes, as demonstrated for neutral carboxy SNARF (residual signal, 0.08% RSD, n = 40) and charged fluorescein (residual signal, 2.5% n = 40). Elution from monolithic columns showed reproducible performance with peak area reproducibility of ~8% (n = 6 columns) in a single sequential elution and the run-to-run reproducibility was 2.4-6.7% RSD (n = 4) for elution from the same bed. The demonstrated ability of this device design and operation to elute from multiple fractionation beds into a single exit channel for sample analysis by fluorescence or electrospray mass spectrometry is a crucial component of an integrated fractionation and assay system for proteomics.

  18. On-line sample cleanup and enrichment chromatographic technique for the determination of ambroxol in human serum.

    PubMed

    Emara, Samy; Kamal, Maha; Abdel Kawi, Mohamed

    2012-02-01

    A sensitive and efficient on-line clean up and pre-concentration method has been developed using column-switching technique and protein-coated µ-Bondapak CN silica pre-column for quantification of ambroxol (AM) in human serum. The method is performed by direct injection of serum sample onto a protein-coated µ-Bondapak CN silica pre-column, where AM is pre-concentrated and retained, while proteins and very polar constituents are washed to waste using a phosphate buffer saline (pH 7.4). The retained analyte on the pre-column is directed onto a C(18) analytical column for separation, with a mobile phase consisting of a mixture of methanol and distilled deionized water (containing 1% triethylamine adjusted to pH 3.5 with ortho-phosphoric acid) in the ratio of 50:50 (v/v). Detection is performed at 254 nm. The calibration curve is linear over the concentration range of 12-120 ng/mL (r(2) = 0.9995). The recovery, selectivity, linearity, precision, and accuracy of the method are convenient for pharmacokinetic studies or routine assays.

  19. High yield sample preconcentration using a highly ion-conductive charge-selective polymer.

    PubMed

    Chun, Honggu; Chung, Taek Dong; Ramsey, J Michael

    2010-07-15

    The development and analysis of a microfluidic sample preconcentration system using a highly ion-conductive charge-selective polymer [poly-AMPS (2-acrylamido-2-methyl-1-propanesulfonic acid)] is reported. The preconcentration is based on the phenomenon of concentration polarization which develops at the boundaries of the poly-AMPS with buffer solutions. A negatively charged polymer, poly-AMPS, positioned between two microchannels efficiently extracts cations through its large cross section, resulting in efficient anion sample preconcentration. The present work includes the development of a robust polymer that is stable over a wide range of buffers with varying chemical compositions. The sample preconcentration effect remains linear to over 3 mM (0.15 pmol) and 500 microM (15 fmol) for fluorescein and TRITC-tagged albumin solutions, respectively. The system can potentially be used for concentrating proteins on microfluidic devices with subsequent analysis for proteomic applications.

  20. Factors governing the pre-concentration of wastewater using forward osmosis for subsequent resource recovery.

    PubMed

    Ansari, Ashley J; Hai, Faisal I; Guo, Wenshan; Ngo, Hao H; Price, William E; Nghiem, Long D

    2016-10-01

    This study demonstrated a technique using forward osmosis (FO) to pre-concentrate the organic matter in raw wastewater, thereby transforming low strength wastewater into an anaerobically digestible solution. The chemical oxygen demand (COD) of raw wastewater was concentrated up to approximately eightfold at a water recovery of 90%. Thus, even low strength wastewater could be pre-concentrated by FO to the range suitable for biogas production via anaerobic treatment. Excessive salinity accumulation in pre-concentrated wastewater was successfully mitigated by adopting ionic organic draw solutes, namely, sodium acetate, and EDTA-2Na. These two draw solutes are also expected to benefit the digestibility of the pre-concentrated wastewater compared to the commonly used draw solute sodium chloride. Significant membrane fouling was observed when operating at 90% water recovery using raw wastewater. Nevertheless, membrane fouling was reversible and was effectively controlled by optimising the hydrodynamic conditions of the cross-flow FO system.

  1. Preconcentration of flavonoids on polyurethane foam and their direct determination by diffuse reflectance spectroscopy.

    PubMed

    Dmitrienko, Stanislava G; Apyari, Vladimir V; Kudrinskaya, Vera A; Stepanova, Alexandra V

    2012-12-15

    Sorption preconcentration of flavonoids quercetin, rutin, chrysin, morin, naringenin and naringin on polyurethane foam was investigated. Several parameters that could affect the preconcentration efficiency were evaluated. The preconcentration efficiency is more than 75% for all the flavonoids except for those that are carbohydrate substituted (preconcentration efficiency less than 11%). This can be used for the separation of these two types of flavonoids. An ability of some flavonoids to absorb light in PUF phase allows their direct determination by diffuse reflectance spectroscopy. Validation of calibration linearity, reproducibility, limits of detection and quantification was performed. The method developed allows to determine flavonoids with detection limits 0.01-0.2 μg mL(-1). The method was utilized for the determination of quercetin in some plant extracts.

  2. On-line controlled documents: Lessons learned

    SciTech Connect

    Cochrell, R.C.; Steele, C.M.

    1995-06-01

    Placing Controlled Documents on-line on a computer network seems like the solution to many problems, one being distribution, with a path toward a paperless office. However, many problems presented themselves as we were designing the system and placing the documents on-line. Although we planned and established a Process Management Team to help work out the bugs, we still encountered many obstacles in the process. This presentation will cover the ``trials and tribulations`` of placing Controlled Documents on a computer network at three different sites. We will discuss the process we went through, the problems we encountered, the software we used, and how we got management to buy into the process.

  3. On-line diagnosis of unrestricted faults

    NASA Technical Reports Server (NTRS)

    Meyer, J. F.; Sundstrom, R. J.

    1974-01-01

    A formal model for the study of on-line diagnosis is introduced and used to investigate the diagnosis of unrestricted faults. A fault of a system S is considered to be a transformation of S into another system S' at some time tau. The resulting faulty system is taken to be the system which looks like S up to time tau, and like S' thereafter. Notions of fault tolerance error are defined in terms of the resulting system being able to mimic some desired behavior as specified by a system similar to S. A notion of on-line diagnosis is formulated which involves an external detector and a maximum time delay within which every error caused by a fault in a prescribed set must be detected. It is shown that if a system is on-line diagnosable for the unrestricted set of faults then the detector is at least as complex, in terms of state set size, as the specification. The use of inverse systems for the diagnosis of unrestricted faults is considered. A partial characterization of those inverses which can be used for unrestricted fault diagnosis is obtained.

  4. Connecting to On-line Data

    NASA Astrophysics Data System (ADS)

    Eichhorn, G.; Astrophysics Datacenter Executive Committee (ADEC)

    2004-05-01

    The Astrophysics Datacenter Executive Committee (ADEC) is coordinating the development of a system to facilitate the linking to on-line data. This system has three components: 1. Unique dataset identifiers. 2. A verification system for identifiers. 3. Permanent links to on-line data sets. 1. The ADEC has agreed on a naming scheme for data sets that allows for the unique identification of any data set. The ADEC data centers will clearly mark their data with these identifiers to allow the generation of links to these data. 2. Each data center has a utility that can check whether a data set identifier is a valid identifier at that center. A central verifier allows third parties access to these individual verifiers through a single portal. 3. The central verifier also provides permanent links to data sets through a central link forwarding system. This makes it possible to move data sets between data centers while maintaining the permanent links. The ADEC plans to first use this system to implement the linking from the literature to on-line data in a collaboration with the AAS and the University of Chicago Press for the AAS journals.

  5. A Fully-Integrated MEMS Preconcentrator for Rapid Gas Sampling (Preprint)

    DTIC Science & Technology

    2006-11-01

    silicon for insulation of the heater. (c) NiCr is sputtered and patterned to make a serpentine by PR patterning and successive wet etching. (d) Au...preconcentrator consisting of a NiCr microheater, a 1 μl preconcentrator, and two microvalves. (b) Device pictures of the layers corresponding to (a...analysis time [8]. II. DESIGN Figure 1 shows a schematic diagram and device pictures of the integrated μPC. It consists of a NiCr microheater

  6. The use of silica-immobilized brown alga (Pilayella littoralis) for metal preconcentration and determination by inductively coupled plasma optical emission spectrometry.

    PubMed

    Carrilho, Elma Neide V M; Nóbrega, Joaquim A; Gilbert, Thomas R

    2003-08-29

    The brown alga Pilayella littoralis was used as a new biosorbent in an on-line metal preconcentration procedure in a flow-injection system. Al, Co, Cu and Fe were determined in lake water samples by inductively coupled plasma optical emission spectrometry (ICP-OES) after preconcentration in a silica-immobilized alga column. Like other algae, P. littoralis exhibited strong affinity for these metals proving to be an effective accumulation medium. Metals were bound at pH 5.5 and were displaced at pH<2 with diluted HCl. The enrichment factors for Cu(II), Fe(III), Al(III) and Co(II) were 13, 7, 16 and 11, respectively. Metal sorption efficiency ranged from 86 to 90%. The method accuracy was assessed by using drinking water certified reference material and graphite furnace atomic absorption spectrometry (GFAAS) as a comparison technique. The column procedure allowed a less time consuming, easy regeneration of the biomaterial and rigidity of the alga provided by its immobilization on silica gel.

  7. Partially pyrolyzed olive pomace sorbent of high permeability for preconcentration of metals from environmental waters.

    PubMed

    El-Sheikh, Amjad H; Sweileh, Jamal A; Saleh, Maysoon I

    2009-09-30

    The aim of this work is to develop a preconcentration procedure of Cd(2+), Zn(2+) and Cu(2+) in environmental waters using olive pomace (OP) prior to their determination by flame atomic absorption spectrometry (FAAS). Raw OP as preconcentrating sorbent was found to have low permeability towards the passed water samples and thus long time was needed. Even reducing the vacuum pressure caused cartridge blockage. Novel preconcentrating sorbents of high permeability were then prepared by heat pretreatment under inert atmosphere (partial pyrolysis) of OP at various temperatures (100, 150, 200, 250 and 300 degrees C). The permeability of OP pyrolyzed at 200 degrees C (sorbent OP-200) was enhanced 11 times relative to the raw OP, which significantly reduced the time required in the preconcentration process. A preconcentration procedure was optimized using OP-200 as preconcentrating sorbent, in which the detection limits were 42 ng L(-1) for Cu(2+), 76 ng L(-1) for Zn(2+) and 172 ng mL(-1) for Cd(2+). The method was linear within the studied concentration range (2-100 ng mL(-1)). The proposed method gave recoveries from 83+/-6 to 103+/-5% for determination of metals in tap water; and recoveries from 81+/-6 to 100+/-6% in well water. The method was validated by comparison with independent method and by analysis of lake sediments LKSD-4 certified reference material.

  8. The design, fabrication and characterization of a silicon microheater for an integrated MEMS gas preconcentrator

    NASA Astrophysics Data System (ADS)

    Yeom, Junghoon; Field, Christopher R.; Bae, Byunghoon; Masel, Richard I.; Shannon, Mark A.

    2008-12-01

    We report the design and fabrication of a microheater unit as a key component of an integrated micro gas preconcentrator that has an ultra-small preconcentrator volume (<0.25 µL) and microvalves for fast injection speeds (<1 ms). Monolithic integration of the microvalves into the microheater of the preconcentrator gives rise to challenges in designing the microheater and implementing thermal isolation for low power and energy consumption. A preconcentrator chamber, 3.5 × 1.5 mm2 in planform area and 40 µm deep, was built in the device layer of a silicon-on-insulator wafer and filled with an array of microposts with a preconcentrator volume of 0.2-0.25 µL. Different generations of the microheaters and their mating dies were fabricated to show the effects of thermal isolation and thermal mass of the system on the performance of the heater. The microheater assembly with the least thermal mass and most thermal isolation can reach 300 °C in 100 ms with 12.3 W of power and is expected to consume less than 2 J during the operation of each preconcentration cycle.

  9. Recent on-line processing procedures for biological samples for determination of trace elements by atomic spectrometric methods

    NASA Astrophysics Data System (ADS)

    Burguera, José L.; Burguera, Marcela

    2009-06-01

    Few of the elements present in nature play a metabolic role in living organisms. According to their abundance, these elements are classified as macro-, micro- or trace elements, representing 93%, 5% and around 1% respectively, of the total body weight. The remaining percentage could be attributed to those elements with unknown biological functions, to others which are present only because of the exposure to polluted environment or to those intentionally introduced into the body for a special treatment. This review summarizes and discusses the most recent publications related to the on-line processing of biological samples for trace element determination using atomic spectrometry-based detectors. Preconcentration/separation procedures based on solid phase or cloud point extractions, electrochemical deposition, microdialysis, as well as chemical vapor generation are the common practice for improving the sensitivity and selectivity of the available atomic spectrometric techniques. The advantages of using isotope dilution mass spectrometry in speciation studies are also emphasized. Digestion or leaching in oxidizing acidic mixtures aided by heat or by ultrasound or microwave radiation, performed off- or on-line, is necessary to previous steps when processing solid biological samples. The most relevant analytical figures of merit such as detection limits, enrichment factors and sample throughput as well as some aspects related to the on-line system configurations and accuracy assessments are critically presented.

  10. Total on-line purchasing system (TOPS)

    SciTech Connect

    Collins, N.

    1995-11-01

    The Information Management Division (IMD) at LLNL is developing a new purchasing system for the Procurement Department. The first major development of this new system is called, {open_quotes}Total On-Line Purchasing System{close_quotes} (TOPS). TOPS will help speed up the requisitioning process by having requisitions electronically entered by requesters and electronically sent to buyers to be put on Purchase Orders. The new purchasing system will use Electronic Commerce (EC)/Electronic Data Interchange (EDI), to help increase transaction flows for shipping notices, RFQs, Quotes, Purchase Orders, and Invoices. ANSI X.12 is the EDI standard that this new EC will use.

  11. On-line diagnosis of unrestricted faults

    NASA Technical Reports Server (NTRS)

    Meyer, J. F.; Sundstrom, R. J.

    1975-01-01

    Attention is given to the formal development of the notion of a discrete-time system and the associated concepts of fault, result of a fault, and error. The considered concept of on-line diagnosis is formalized and a diagnosis using inverse machines is discussed. The case of an inverse which is lossless is investigated. It is found that in such a case the class of unrestricted faults can be diagnosed with a delay equal to the delay of losslessness of the inverse system.

  12. Interpolating Functions on Lines in 3-Space

    DTIC Science & Technology

    2000-01-01

    numbers comprise the compilation report: ADP011967 thru ADPO12009 UNCLASSIFIED Interpolating Functions on Lines in 3-Space Martin Peternell and Helmut...reproduction in any form reserved. 352 M. Peternell and H. Pottmann §2. Lines in Space An oriented line L in Euclidean 3-space E 3 is determined by a...intersection r = Q n T is a quadratic cone with vertex Z. The intersection e = E n T is a hyperplane 354 M. Peternell and H. Pottmann X t) Fig. 2. Local

  13. On-line coupling of solid-phase extraction to high-performance liquid chromatography for determination of estrogens in environment.

    PubMed

    Wang, Shuo; Huang, Wei; Fang, Guozhen; He, Jinxing; Zhang, Yan

    2008-01-14

    A method based on on-line solid-phase extraction (SPE) coupling to high-performance liquid chromatography (HPLC) for the determination of estrogens has been developed. This method can continuously perform extraction of estrone, estradiol, estriol and diethylstilbestrol from aqueous samples without any other pretreatment, which can then be analyzed by HPLC with a UV detector at 230 nm. A pre-concentration column was adapted with methanol/water for chromatographic separation and two kinds of sorbents were involved, which are octadecyl-bonded silica and cigarette filter. The condition of pH of samples, sample loading flow rate and desorption time were all optimized, and the performances of both two sorbents were satisfactory. The on-line SPE system requires very low maintenance and just involved a switching-valve-filter system and a flow-inject pump, and the operation of the whole SPE-HPLC instrumentation is quite simple. The detection limits for pre-concentrating 50 mL of standard solution using cigarette filter as sorbent ranged from 0.98 to 78.1 ngL(-1). The enhancement factors were in the range of 197-326. The recoveries of estrogens spiked in real water samples ranged from 85 to 112%. The precisions for nine replicate measurements of a standard mixture (5.0 microgL(-1)) were in the range of 1.0-3.4%.

  14. Quantifying spatio-temporal dynamics of biomarker pre-concentration and depletion in microfluidic systems by intensity threshold analysis

    PubMed Central

    Rohani, Ali; Varhue, Walter; Su, Yi-Hsuan; Swami, Nathan S.

    2014-01-01

    Microfluidic systems are commonly applied towards pre-concentration of biomarkers for enhancing detection sensitivity. Quantitative information on the spatial and temporal dynamics of pre-concentration, such as its position, extent, and time evolution are essential towards sensor design for coupling pre-concentration to detection. Current quantification methodologies are based on the time evolution of fluorescence signals from biomarkers within a statically defined region of interest, which does not offer information on the spatial dynamics of pre-concentration and leads to significant errors when the pre-concentration zone is delocalized or exhibits wide variations in size, shape, and position over time under the force field. We present a dynamic methodology for quantifying the region of interest by using a statistical description of particle distribution across the device geometry to determine the intensity thresholds for particle pre-concentration. This method is applied to study the delocalized pre-concentration dynamics under an electrokinetic force balance driven by negative dielectrophoresis, for aligning the pre-concentration and detection regions of neuropeptide Y, and for quantifying the polarizability dispersion of silica nano-colloids with frequency of the force field. We envision the application of this automated methodology on data from 2D images and 3D Z-stacks for quantifying pre-concentration dynamics over delocalized regions as a function of the force field. PMID:25538800

  15. On-line and Mobil Learning Activities

    NASA Astrophysics Data System (ADS)

    Ackerman, S. A.; Whittaker, T. M.; Jasmin, T.; Mooney, M. E.

    2012-12-01

    Introductory college-level science courses for non-majors are critical gateways to imparting not only discipline-specific information, but also the basics of the scientific method and how science influences society. They are also indispensable for student success to degree. On-line, web-based homework (whether on computers or mobile devices) is a rapidly growing use of the Internet and is becoming a major component of instruction in science, replacing delayed feedback from a few major exams. Web delivery and grading of traditional textbook-type questions is equally effective as having students write them out for hand grading, as measured by student performance on conceptual and problem solving exams. During this presentation we will demonstrate some of the interactive on-line activities used to teach concepts and how scientists approach problem solving, and how these activities have impacted student learning. Evaluation of the activities, including formative and summative, will be discussed and provide evidence that these interactive activities significantly enhance understanding of introductory meteorological concepts in a college-level science course. More advanced interactive activities are also used in our courses for department majors, some of these will be discussed and demonstrated. Bring your mobile devices to play along! Here is an example on teaching contouring: http://profhorn.aos.wisc.edu/wxwise/contour/index.html

  16. Self nanoprecipitating preconcentrate of tamoxifen citrate for enhanced bioavailability.

    PubMed

    Kapse, Sonali V; Gaikwad, Rajiv V; Samad, Abdul; Devarajan, Padma V

    2012-06-15

    We disclose a self nanoprecipitating preconcentrate (SNP) of tamoxifen citrate (TMX), which forms TMX loaded polymeric nanoparticles, on dilution with aqueous media. SNP comprised TMX, polymer (Kollidon SR) and surfactant/s dissolved in a pharmaceutically acceptable vehicle. Binary surfactant mixtures of Aerosol OT (AOT) with Tween 80 revealed synergistic reduction in surface tension to enable both high entrapment efficiency (EE) and low particle size (PS). Synergism of the surfactants was confirmed by molecular interaction parameter(β(σ)). Combination of AOT and Tween 80 resulted in EE (∼85%) and PS (<250nm). Formation of TMX-KSR nanoparticles in situ was reproducible under most experimental conditions and exhibited pH independent behavior. Dilution volume (>80mL) influenced both PS and EE while dilution temperature influenced only PS. Marginal increase in size was evident at the end of 1h nevertheless was not of concern as TMX SNP exhibited near complete release in 1h. DSC and XRD studies revealed amorphous nature of TMX in nanoparticles. FTIR imaging confirmed uniform distribution of TMX in nanoparticles. ESEM and TEM revealed spherical nanoparticles. Biodistribution studies of (99m)Tc labeled TMX SNP in rats revealed no significant absorption however oral pharmacokinetics revealed enhanced oral bioavailability of TMX (165%) compared to TMX suspension. SNP presents a new in situ approach, for design of drug loaded polymeric nanoparticles. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. A poly-methylmethacrylate electrophoresis microchip with sample preconcentrator

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Cheng; Ho, Hsiao-Ching; Tseng, Chien-Kai; Hou, Shao-Qin

    2001-05-01

    A microstructure on poly-methylmethacrylate (PMMA) for sample concentration and electrophoresis was fabricated. This microfabricated structure was able to increase the detection signal and lower the amount of sample used in electrophoretic analysis. The thin-film electrode located at the T-intersection of the sample injection and separation channels provides the current path for the injection channel, but restrains the DNA molecules from passing through. This can accumulate DNA molecules and increase the concentration before performing the electrophoretic analysis. This microstructure was fabricated using krypton fluoride (KrF) excimer laser photo-ablation and fusion bonding techniques. The excimer laser photo-ablation performs rapid prototyping with great flexibility in design changes. The PMMA material is much cheaper than other materials, for example glass and silicon, used in capillary electrophoresis and concentration. The applied electrical field was 300 V cm-1 for the DNA concentration in this microstructure. Experiments show that the DNA concentration was saturated within 200 s after the DNA molecules first reached the injection tee. The DNA fragments can be concentrated up to five times greater than samples without a concentrator at the injection tee. The separation results also demonstrated that the detected signal intensities of the separated DNA fragments in the tee-type chip with a sample preconcentrator were five times greater than that obtained in a conventional cross-type capillary electrophoresis chip with an identical initial sample concentration.

  18. Preconcentration Method on Modified Silica Fiber for Chromium Speciation

    PubMed Central

    Chahal, Varinder Kaur; Singh, Raghubir; Malik, Ashok Kumar; Matysik, Frank-Michael; Puri, Jugal Kishore

    2012-01-01

    A new method involving pre-concentration on modified silica fiber is described for the speciation of chromium(III) [Cr(III)] and chromium(VI) [Cr(VI)] in aqueous media. This method is based on the different chelating behavior of Cr(III) and Cr(VI) with morpholine-4-carbodithioate (MDTC). Both complexes are extracted on silica fiber modified by sol-gel technology by using 3-aminopropyltriethoxysilane (APS) as a precursor. All extracted samples are directly injected into an high-performance liquid chromatography injector for the simultaneous determination of Cr(III) and Cr(VI). Cr(VI) forms two different complexes, and Cr(III) forms a single complex with MDTC. Therefore, the concentration of Cr(VI) is determined directly from the peak area obtained at 5.4 min; whereas, the assay of Cr(III) is based on subtracting the peak area of Cr(VI) from the total peak area obtained at 4.3 min. Under the optimized conditions, the limits of detection for Cr(III) and Cr(VI) are found to be 0.7 ng/mL and 0.2 ng/mL, respectively. PMID:22291053

  19. A novel preconcentration technique for the PIXE analysis of water

    NASA Astrophysics Data System (ADS)

    Savage, J. M.; Fernandez, R. F.; Zhang, W.; Robertson, J. D.; Majidi, V.

    1995-05-01

    The potential of using dried algae as a novel preconcentration technique for the analysis of water samples by PIXE was examined. The algae cells were found to contain significant levels of P and S, indicative of phosphorous- and sulfur-containing groups on the cell wall or inside the algae cells which may serve as potential binding sites for metal ions. When C. vulgaris was used on mixed metal solutions, linear responses were observed for Ag +, Ba 2+, and Cd 2+ in the concentration range from 10 ng/g to 1 μg/g; for Cu 2+ and Pb 2+ from 10 ng/g to 5 μg/g; and for Hg 2+ from 10 ng/g to 10 μg/g. When S. bacillaris was used, linear responses were observed from 10 ng/g up to 10 μg/g for all of the metal cations investigated. The PIXE results demonstrated that metal binding at low concentrations involves replacement of sodium on the cell wall and that at high concentrations magnesium was also replaced. Competitive binding studies indicate that the metal ions, Ag +, Ba 2+, Cd 2+, Cu 2+, and Pb 2+, share common binding sites with binding efficiencies varying in the sequence of Pb 2+ > Cu 2+ > Ag 2+ > Cd 2+ > Ba 2+. The binding of Hg 2+ involved a different binding site with an increase in binding efficiency in the presence of Ag +.

  20. Automation and integration of multiplexed on-line sample preparation with capillary electrophoresis for DNA sequencing

    SciTech Connect

    Tan, H.

    1999-03-31

    The purpose of this research is to develop a multiplexed sample processing system in conjunction with multiplexed capillary electrophoresis for high-throughput DNA sequencing. The concept from DNA template to called bases was first demonstrated with a manually operated single capillary system. Later, an automated microfluidic system with 8 channels based on the same principle was successfully constructed. The instrument automatically processes 8 templates through reaction, purification, denaturation, pre-concentration, injection, separation and detection in a parallel fashion. A multiplexed freeze/thaw switching principle and a distribution network were implemented to manage flow direction and sample transportation. Dye-labeled terminator cycle-sequencing reactions are performed in an 8-capillary array in a hot air thermal cycler. Subsequently, the sequencing ladders are directly loaded into a corresponding size-exclusion chromatographic column operated at {approximately} 60 C for purification. On-line denaturation and stacking injection for capillary electrophoresis is simultaneously accomplished at a cross assembly set at {approximately} 70 C. Not only the separation capillary array but also the reaction capillary array and purification columns can be regenerated after every run. DNA sequencing data from this system allow base calling up to 460 bases with accuracy of 98%.

  1. On-line solid-phase extraction for liquid chromatography-mass spectrometry analysis of pesticides.

    PubMed

    Lucci, Paolo; Núñez, Oscar

    2014-10-01

    Public concern about pesticides in food and water has increased dramatically in the last two decades. In order to guarantee consumers' health and safety, analytical methods that could provide fast and reliable answers without compromising accuracy and precision are required. Sample treatment is probably the most tedious and time-consuming step in many analytical procedures and, despite the significant advances in chromatographic separations and mass spectrometry techniques, sample treatment is still one of the most important parts of the analytical process for achieving good analytical results. Therefore, over the last years, considerable efforts have been made to simplify the stage and to develop fast, accurate, and robust methods that allow the determination of a wide range of pesticides without compromising the integrity of the extraction process. This review article intends to give a short overview of recently developed on-line solid-phase extraction, preconcentration, and clean-up procedures for the determination of pesticides in complex matrices by liquid chromatography-mass spectrometry techniques.

  2. A cryogen-free refrigerating preconcentration device for the measurement of C2 to C4 hydrocarbons in ambient air.

    PubMed

    Peng, Hong; Wang, Jianwei; Shen, Zheng; Wu, Dapeng; Guan, Yafeng

    2011-02-07

    A cryogen-free refrigerating preconcentration device for the enrichment of trace amounts of highly volatile organic compounds in the atmosphere prior to analysis has been designed and evaluated. The device consists of a microtrap housed in an insulated box, which is cooled by a conventional refrigeration unit. Experimental parameters, including adsorbent mass, trapping temperature, and thermal desorption temperature, were optimized. The on-line coupling of the device to a GC allows sufficient enrichment and separation of C2 to C4 hydrocarbons in less than 40 min without a second cryotrap. The target compounds analysis showed good linearity (correlation coefficients >0.99) and repeatability (relative standard deviation <5%). Detection limits for the 10 volatile organic compounds ranged from 14 ppt to 52 ppt, under the conditions of a 500 mL sampling volume and -10 °C trapping temperature. Real air sample measurements were conducted at an urban site, and five VOCs including ethane, ethene, propane, propene and 1-butene were detected and quantified.

  3. On-line consolidation of thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Shih, Po-Jen

    An on-line consolidation system, which includes a computer-controlled filament winding machine and a consolidation head assembly, has been designed and constructed to fabricate composite parts from thermoplastic towpregs. A statistical approach was used to determine the significant processing parameters and their effect on the mechanical and physical properties of composite cylinders fabricated by on-line consolidation. A central composite experimental design was used to select the processing conditions for manufacturing the composite cylinders. The thickness, density, void content, degree of crystallinity and interlaminar shear strength (ILSS) were measured for each composite cylinder. Micrographs showed that complete intimate contact and uniform fiber-matrix distribution were achieved. The degree of crystallinity of the cylinders was found to be in the range of 25-30%. Under optimum processing conditions, an ILSS of 58 MPa and a void content of <1% were achieved for APC-2 (PEEK/Carbon fiber) composite cylinders. An in-situ measurement system which uses a slip ring assembly and a computer data acquisition system was developed to obtain temperature data during winding. Composite cylinders were manufactured with eight K-type thermocouples installed in various locations inside the cylinder. The temperature distribution inside the composite cylinder during winding was measured for different processing conditions. ABAQUS finite element models of the different processes that occur during on-line consolidation were constructed. The first model was used to determine the convective heat transfer coefficient for the hot-air heat source. A convective heat transfer coefficient of 260 w/msp{2°}K was obtained by matching the calculated temperature history to the in-situ measurement data. To predict temperature distribution during winding an ABAQUS winding simulation model was developed. The winding speed was modeled by incrementally moving the convective boundary conditions

  4. Arsenic speciation in environmental waters by a new specific phosphine modified polymer microsphere preconcentration and HPLC-ICP-MS determination.

    PubMed

    Jia, Xiaoyu; Gong, Dirong; Wang, Jiani; Huang, Fuyi; Duan, Taicheng; Zhang, Xian

    2016-11-01

    A new specific phosphine modified polymer microsphere (PPMs) was designed and used as the core adsorbent to comprehensively enrich both inorganic and organic arsenic species in environmental waters by on line solid-phase extraction (SPE). Avoiding any redox reagent, all the four arsenic species have been quantitatively retained on the home made mini-column with large number of positively charged adsorption groups, and then eluted rapidly (within seconds) with a mixed solution of ammonium nitrate and ammonium dihydrogen phosphate. The trace separation and determination of As(III), DMA, MMA and As(V) species have been simultaneously achieved by high performance liquid chromatography hyphenated to inductively coupled plasma spectrometry (HPLC-ICP-MS) technique. This work has developed a versatile tri-n-butylphosphine functionalized polymer microsphere for an efficient and reliable on-line of simultaneous preconcentration and detection of inorganic and organic arsenic speciation. Under the optimized experimental conditions, the enrichment factors obtained for As(III) and DMA with 25mL sample solution were 28, while for MMA and As(V) reached 30. The low detection limits of 1.2ngL(-1), 0.96ngL(-1), 0.82ngL(-1) and 0.91ngL(-1), with the relative standard deviations (RSDs) of 3.9%, 5.6%, 3.2% and 4.5% were obtained for As(III), DMA, MMA and As(V), respectively. The developed method was validated by analyzing Certified Reference Materials GSBZ 07-3171-2014, promising for routine monitoring of arsenic species in lake water, river water and seawater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. On-line process control monitoring system

    DOEpatents

    O'Rourke, Patrick E.; Van Hare, David R.; Prather, William S.

    1992-01-01

    An on-line, fiber-optic based apparatus for monitoring the concentration of a chemical substance at a plurality of locations in a chemical processing system comprises a plurality of probes, each of which is at a different location in the system, a light source, optic fibers for carrying light to and from the probes, a multiplexer for switching light from the source from one probe to the next in series, a diode array spectrophotometer for producing a spectrum from the light received from the probes, and a computer programmed to analyze the spectra so produced. The probes allow the light to pass through the chemical substance so that a portion of the light is absorbed before being returned to the multiplexer. A standard and a reference cell are included for data validation and error checking.

  6. NASDA's Advanced On-Line System (ADOLIS)

    NASA Technical Reports Server (NTRS)

    Yamamoto, Yoshikatsu; Hara, Hideo; Yamada, Shigeo; Hirata, Nobuyuki; Komatsu, Shigenori; Nishihata, Seiji; Oniyama, Akio

    1993-01-01

    Spacecraft operations including ground system operations are generally realized by various large or small scale group work which is done by operators, engineers, managers, users and so on, and their positions are geographically distributed in many cases. In face-to-face work environments, it is easy for them to understand each other. However, in distributed work environments which need communication media, if only using audio, they become estranged from each other and lose interest in and continuity of work. It is an obstacle to smooth operation of spacecraft. NASDA has developed an experimental model of a new real-time operation control system called 'ADOLIS' (ADvanced On-Line System) adopted to such a distributed environment using a multi-media system dealing with character, figure, image, handwriting, video and audio information which is accommodated to operation systems of a wide range including spacecraft and ground systems. This paper describes the results of the development of the experimental model.

  7. On-line Resources for Xenopus

    PubMed Central

    Bowes, Jeff

    2015-01-01

    Summary Since the advent of computational methods in biology the quantity of biological data has grown exponentially. These data support genomic, genetic, developmental, and other forms of biological experimentation. The number of on-line resources has kept pace with the growth in data. Xenopus has perhaps lagged some of the other model organisms in developing resources but is now quickly catching up. There are now a number of well-established and developing resources for Xenopus. This chapter looks beyond the widely-known public databases, Genbank and the EBI, and describes how the researcher can use a number of central sites such as Xenbase, UniProtKB, and major genome browsers to navigate to a variety of different resources. PMID:22956109

  8. Babar On-Line Prototype Development

    NASA Astrophysics Data System (ADS)

    Abrams, G. S.; Jacobsen, R. G.; Lewis, S. A.; Ogren, Z.; Glanzman, T.; Weinstein, A.; White, J. L.

    The BaBar On-line system has begun construction of a prototype which will serve as a test bench and beam test system. The system architecture is based on single board computers running VxWorks, linked to Unix workstations via ethernet (as well as tests with FDDI). This early system is based on the Experimental Physics and Industrial Control System, which provides both control of state transitions and monitoring facilities. This functionality is achieved with no software investment: native EPICS utilities are used to develop screen displays and control panels. Emphasis at this time is on the incorporation of reusable code. The first application of this prototype is the creation of a testbed for the BaBar dataflow research and development.

  9. On-line tritium production monitor

    DOEpatents

    Mihalczo, J.T.

    1993-11-23

    A scintillation optical fiber system for the on-line monitoring of nuclear reactions in an event-by-event manner is described. In the measurement of tritium production one or more optical fibers are coated with enriched {sup 6}Li and connected to standard scintillation counter circuitry. A neutron generated {sup 6}Li(n)T reaction occurs in the coated surface of {sup 6}Li-coated fiber to produce energetic alpha and triton particles one of which enters the optical fiber and scintillates light through the fiber to the counting circuit. The coated optical fibers can be provided with position sensitivity by placing a mirror at the free end of the fibers or by using pulse counting circuits at both ends of the fibers. 5 figures.

  10. On-line tritium production monitor

    DOEpatents

    Mihalczo, John T.

    1993-01-01

    A scintillation optical fiber system for the on-line monitoring of nuclear reactions in an event-by-event manner is described. In the measurement of tritium production one or more optical fibers are coated with enriched .sup.6 Li and connected to standard scintillation counter circuitry. A neutron generated .sup.6 Li(n )T reaction occurs in the coated surface of .sup.6 Li-coated fiber to produce energetic alpha and triton particles one of which enters the optical fiber and scintillates light through the fiber to the counting circuit. The coated optical fibers can be provided with position sensitivity by placing a mirror at the free end of the fibers or by using pulse counting circuits at both ends of the fibers.

  11. On-line chemical composition analyzer development

    SciTech Connect

    Roberts, M.J.; Garrison, A.A.; Muly, E.C.; Moore, C.F.

    1992-02-01

    The energy consumed in distillation processes in the United States represents nearly three percent of the total national energy consumption. If effective control of distillation columns can be accomplished, it has been estimated that it would result in a reduction in the national energy consumption of 0.3%. Real-time control based on mixture composition could achieve these savings. However, the major distillation processes represent diverse applications and at present there does not exist a proven on-line chemical composition sensor technology which can be used to control these diverse processes in real-time. This report presents a summary of the findings of the second phase of a three phase effort undertaken to develop an on-line real-time measurement and control system utilizing Raman spectroscopy. A prototype instrument system has been constructed utilizing a Perkin Elmer 1700 Spectrometer, a diode pumped YAG laser, two three axis positioning systems, a process sample cell land a personal computer. This system has been successfully tested using industrially supplied process samples to establish its performance. Also, continued application development was undertaken during this Phase of the program using both the spontaneous Raman and Surface-enhanced Raman modes of operation. The study was performed for the US Department of Energy, Office of Industrial Technologies, whose mission is to conduct cost-shared R D for new high-risk, high-payoff industrial energy conservation technologies. Although this document contains references to individual manufacturers and their products, the opinions expressed on the products reported do not necessarily reflect the position of the Department of Energy.

  12. Ultrasonication-assisted extraction and preconcentration of medicinal products from herb by ionic liquids.

    PubMed

    Bi, Wentao; Tian, Minglei; Row, Kyung Ho

    2011-07-15

    Ionic liquid-based extraction of medicinal or useful compounds from plants was investigated as an alternative to supercritical fluid, cloud point and conventional organic solvent extractions. The method integrated extraction and preconcentration. Medicinal products were first extracted by an ionic liquid solution, part of which was then converted to a hydrophobic form by anion metathesis for preconcentration. The remaining soluble ionic liquid acted as a dispersive agent to enhance the efficiency of preconcentration. Protein in the extract was precipitated spontaneously without addition of further solvents. Ultrasonication assisted this method for extraction and preconcentration of cryptotanshinone, tanshinone I and tanshinone II A from Salvia Miltiorrhiza Bunge. 0.233 mg g(-1), 0.695 mg g(-1) and 0.682 mg g(-1) of each, respectively, were extracted using [OMIM][Cl], and preconcentrated in a [OMIM][PF(6)] phase at respective concentrations of 148.1, 507.1 and 486.1 μg mL(-1). The method exhibited potential applicability with other medicinal products. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Experimental investigation and analysis of continuous flow through trace gas preconcentrator

    NASA Astrophysics Data System (ADS)

    Kim, Jihyun

    2013-11-01

    It was proposed by Muntz et al. in 2004 to study a micro/mesoscale continuous flow through trace gas preconcentrator, which could avoid the time fidelity problem. The preconcentrator for rarefied trace gas analysis, which is one part of a gas detector or analyzer, has been built and consists of a main flow channel, pumping chambers, and separation membranes that are located upper and lower surface of the main flow channel. The preconcentration is not from stop, adsorption, and release, but is caused by the gradually decreasing cross section of the main flow channel until release through the detection unit such as gas chromatography, mass spectrometry, or optical diagnostics. This has the possibility of achieving concentration increase of various gases in a carrier gas by using relatively simple micro/macroscale mass diffusion separation stages, and is suitable for improving the time accuracy of analytical systems. A series of experiments were conducted in an attempt to validate the available numerical data, such as the concentration and gas flow speed of the newly continuous preconcentration technology. This study involved experimental investigations to obtain a base-line comparison of the existing numerical predictions provided by the prototype preconcentrator.

  14. Preconcentration of diluted biochemical samples using microchannel with integrated nanoscale Nafion membrane.

    PubMed

    Chao, Chen-Chiao; Chiu, Ping-Hsien; Yang, Ruey-Jen

    2015-04-01

    A microfluidic preconcentration device comprising a microchannel and a surface-patterned nanoscale Nafion membrane is proposed. Given the application of an electric field across the chip, the nanopore within Nafion membrane becomes ion selective due to an overlapping of the electric double layer. The resulting difference in flux of the co- and counter-ions within the membrane nanopore prompts the formation of a concentration gradient and leads to a gradual accumulation of the co-ions at the micro-nano junction. It is shown experimentally that the rate of concentration and the preconcentration factor both increase with an increasing electrical field intensity. The preconcentration performance in a straight microchannel is compared with that in a convergent microchannel using fluorescein disodium salt dehydrate and Fluorescein isothiocyanate (FITC)-labeled bovine serum albumin samples. The results show that the reduced cross-sectional area of the convergent microchannel increases the preconcentration factor compared to that obtained in a straight microchannel and yields a significant reduction in the preconcentration time.

  15. A micro gas preconcentrator with improved performance for pollution monitoring and explosives detection.

    PubMed

    Camara, E H M; Breuil, P; Briand, D; de Rooij, N F; Pijolat, C

    2011-03-04

    This paper presents the optimization of a micro gas preconcentrator based on a micro-channel in porous and non-porous silicon filled with an adequate adsorbent. This micro gas preconcentrator is both applicable in the fields of atmospheric pollution monitoring (Volatil organic compounds--VOCs) and explosives detection (nitroaromatic compounds). Different designs of micro-devices and adsorbent materials have been investigated since these two parameters are of importance in the performances of the micro-device. The optimization of the device and its operation were driven by its future application in outdoor environments. Parameters such as the preconcentration factor, cycle time and the influence of the humidity were considered along the optimization process. As a result of this study, a preconcentrator with a total cycle time of 10 min and the use of single wall carbon nanotubes (SWCNTs) as adsorbent exhibits a good preconcentration factor for VOCs with a limited influence of the humidity. The benefits of using porous silicon to modify the gas desorption kinetics are also investigated. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Different strategies for the preconcentration and separation of parabens by capillary electrophoresis.

    PubMed

    Maijó, Irene; Borrull, Francesc; Aguilar, Carme; Calull, Marta

    2013-02-01

    Several strategies, namely, large volume sample stacking (LVSS), field-amplified sample injection (FASI), sweeping, and in-line SPE-CE, were investigated for the simultaneous separation and preconcentration of a group of parabens. A BGE consisting of 20 mM sodium dihydrogenphosphate (pH 2.28) and 150 mM SDS with 15% ACN was used for the separation and preconcentration of the compounds by sweeping, and a BGE consisting of 30 mM sodium borate (pH 9.5) was used for the separation and preconcentration of the compounds by LVSS, FASI, and in-line SPE-CE. Several factors affecting the preconcentration process were investigated in order to obtain the maximum enhancement of sensitivity. The LODs obtained for parabens were in the range of 18-27, 3-4, 2, and 0.01-0.02 ng/mL, and the sensitivity evaluated in terms of LODs was improved up to 29-, 77-, 120-, and 18,400-fold for sweeping, LVSS, FASI, and in-line SPE-CE, respectively. These preconcentration techniques showed potential as good strategies for focusing parabens. The four methods were validated with standard samples to show the potential of these techniques for future applications in real samples, such as biological and environmental samples.

  17. Electrokinetic Sample Preconcentration and Hydrodynamic Sample Injection for Microchip Electrophoresis Using a Pneumatic Microvalve

    SciTech Connect

    Cong, Yongzheng; Katipamula, Shanta; Geng, Tao; Prost, Spencer A.; Tang, Keqi; Kelly, Ryan T.

    2016-02-01

    A microfluidic platform was developed to perform online electrokinetic sample preconcentration and rapid hydrodynamic sample injection for electrophoresis using a single microvalve. The PDMS microchip consists of a separation channel, a side channel for sample introduction, and a control channel which is used as a pneumatic microvalve aligned at the intersection of the two flow channels. The closed microvalve, created by multilayer soft lithography, can serve as a preconcentrator under an applied electric potential, enabling current to pass through while blocking bulk flow. Once analytes are concentrated, the valve is briefly opened and the stacked sample is pressure injected into the separation channel for electrophoretic separation. Fluorescently labeled peptides were enriched by a factor of ~450 in 230 s. The performance of the platform was validated by the online preconcentration, injection and electrophoretic separation of fluorescently labeled peptides. This method enables both rapid analyte concentration and controlled injection volume for high sensitivity, high resolution capillary electrophoresis.

  18. Preconcentrator-based sensor µ-system for low-level benzene detection

    NASA Astrophysics Data System (ADS)

    Ivanov, P.; Gràcia, I.; Blanco, F.; Raskin, J.-P.; Cumeras, R.; Sabaté, N.; Vilanova, X.; Correig, X.; Fonseca, L.; Figueras, E.; Santander, J.; Cané, C.

    2008-12-01

    In this paper, a preconcentrator-based sensor μ-system for low level benzene detection is presented. It consists of a spiral-shaped μ-reconcentrator with dimensions of 10cm × 300μm × 300μm, followed by a μ-hotplate sensor matrix. The μ-preconcentrator was fabricated on a silicon wafer by means of DRIE and anodic bonding techniques. To obtain the concentration factor of the fabricated devices, a GC/MS: Shimadzu-QP5000 equipment was used. The results obtained showed excellent repeatability and preconcentration factors up to 286. A considerable improvement (1500%) in the sensor responses was achieved with Pd doped SnO2 sensors. The small size of the manufactured devices enables their incorporation in an integrated GC/MS gas sensor system.

  19. Influence of the Adsorbent Material in the Performances of a Micro Gas Preconcentrator

    NASA Astrophysics Data System (ADS)

    Camara, E. H. M.; Breuil, P.; Briand, D.; Guillot, L.; Pijolat, C.; Viricelle, J. P.; de Rooij, N. F.

    2009-05-01

    This paper presents the evaluation of different adsorbents for the improvement of the performances of a gas preconcentrator by targeting the adsorption of a large range of volatiles organics compounds (VOCs) The objectives of this work are to find the adequate adsorbent for a given gas target in specific experimental conditions and to select an efficient deposition process. Results related to the characterization of carbon nanopowders, carbon nanotubes (single walled (SWCNTs) and multi walled (MWCNTs)) and polymer (Tenax TA) for the development of a device for benzene preconcentration are reported. These results provide guidelines to define the right adsorbent for the preconcentration of benzene according to some specific criterions such as a large specific surface, a high adsorption capacity and low desorption temperature.

  20. Effects of carbon dioxide on peak mode isotachophoresis: simultaneous preconcentration and separation.

    PubMed

    Khurana, Tarun K; Santiago, Juan G

    2009-05-21

    We present a method that achieves simultaneous preconcentration and separation of analytes using peak-mode isotachophoresis with a single step injection in simple, off-the-shelf microchannels or capillaries. We leverage ions resulting from dissolved atmospheric carbon dioxide to weakly disrupt isotachophoretic preconcentration and induce separation of analyte species. We experimentally study the region between the leading and trailing electrolytes, and individually identify the carbonate and carbamate zones that result from the hydration and carbamation reaction of dissolved atmospheric carbon dioxide, respectively. The width of these zones and the gradient regions between them grow with time and create an electric field gradient that causes analytes to separate. Using this assay, we achieve focusing and separation of a 25 bp DNA ladder in a straight, 34 microm wide microchannel in a single loading step. As a demonstration of the fractionation capabilities of the assay, we show simultaneous preconcentration and separation of a DNA ladder from two proteins, GFP and allophycocyanin.

  1. CE analysis of single wood cells performing hydrolysis and preconcentration in open microchannels.

    PubMed

    Rokhas, Maria Khihon; Mikkonen, Saara; Beyer, Juliane; Jacksén, Johan; Emmer, Åsa

    2014-02-01

    In the present work, monosaccharides from pulp samples and single wood fibers were analyzed with CE, using indirect detection due to the lack of chromophores on the monosaccharides. The hydrolysis degradation of cellulose and hemicellulose into monosaccharides was performed using TFA, either in bulk scale or in microscale. In the microscale, one single wood fiber was hydrolyzed in an open microchannel manufactured on a silicon microchip with the dimensions 50 μm × 50 μm (length 1 or 3 cm). The low monosaccharide amounts derived from a single fiber implied that a preconcentration step was necessary to increase the detectability. Thus, an electromigration preconcentration of the hydrolyzed samples was performed within the microchannel, which resulted in a significantly enhanced signal intensity of the monosaccharides. In addition to the experimental study, computer simulations were performed regarding the preconcentration step of monosaccharides. The results from these simulations correlated well with the experimental results.

  2. Preconcentration and detection of mercury with bioluminescent bioreporter E. coli ARL1.

    PubMed

    Solovyev, Andrey I; Koštejn, Martin; Kuncova, Gabriela; Dostálek, Pavel; Rohovec, Jan; Navrátil, Tomáš

    2015-10-01

    Cell wall envelopes treated with sodium hydroxide and spray-dried were used as mercury sorbents. The sorbent having sorption capacity 17.7 ± 0.1 μmol/g determined was employed for preconcentration of mercury containing 1-10 ng/L. After preconcentration, bioavailable mercury was detected in samples of soil, stream, and tap water via induction of bioluminescence of E. coli ARL1. Iron and manganese at concentrations of tenth microgram per liter interfered bioluminescence detection of mercury. In tap water was detected semiquantitatively 0.127 ± 0.1 nmol/L by the induction of bioluminescence of E. coli ARL1 in medium with tryptone after preconcentration using a method of standard addition.

  3. DIRECT MERCURY ANALYSIS IN ENVIRONMENTAL SOLIDS BY ICPMS WITH ON-LINE SAMPLE ASHING AND MERCURY PRECONCENTRATION USING A DIRECT MERCURY ANALYZER

    EPA Science Inventory

    Mercury is a persistent, mobile, and highly toxic pollutant. It's biogeochemistry is probably the most complex of any metal. For these reasons, the U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD), has developed a comprehensive res...

  4. Application of cotton as a solid phase extraction sorbent for on-line preconcentration of copper in water samples prior to inductively coupled plasma optical emission spectrometry determination.

    PubMed

    Faraji, Mohammad; Yamini, Yadollah; Shariati, Shahab

    2009-07-30

    Copper, as a heavy metal, is toxic for many biological systems. Thus, the determination of trace amounts of copper in environmental samples is of great importance. In the present work, a new method was developed for the determination of trace amounts of copper in water samples. The method is based on the formation of ternary Cu(II)-CAS-CTAB ion-pair and adsorption of it into a mini-column packed with cotton prior applying inductively coupled plasma optical emission spectrometry (ICP-OES). The experimental parameters that affected the extraction efficiency of the method such as pH, flow rate and volume of the sample solution, concentration of chromazurol S (CAS) and cethyltrimethylammonium bromide (CTAB) as well as type and concentration of eluent were investigated and optimized. The ion-pair (Cu(II)-CAS-CTAB) was quantitatively retained on the cotton under the optimum conditions, then eluted completely using a solution of 25% (v/v) 1-propanol in 0.5 mol L(-1) HNO(3) and directly introduced into the nebulizer of the ICP-OES. The detection limit (DL) of the method for copper was 40 ng L(-1) (V(sample)=100mL) and the relative standard deviation (R.S.D.) for the determination of copper at 10 microg L(-1) level was found to be 1.3%. The method was successfully applied to determine the trace amounts of copper in tap water, deep well water, seawater and two different mineral waters, and suitable recoveries were obtained (92-106%).

  5. DIRECT MERCURY ANALYSIS IN ENVIRONMENTAL SOLIDS BY ICPMS WITH ON-LINE SAMPLE ASHING AND MERCURY PRE-CONCENTRATION USING THE DIRECT MERCURY ANALYZER

    EPA Science Inventory



    A Direct Mercury Analyzer based on sample combustion and mercury concentration by gold amalgamation, followed by atomic absorption determination, was interfaced with a quadrupole and a magnet sector ICPMS. In this paper, we discuss design and operating parameters and eval...

  6. DIRECT MERCURY ANALYSIS IN ENVIRONMENTAL SOLIDS BY ICPMS WITH ON-LINE SAMPLE ASHING AND MERCURY PRECONCENTRATION USING A DIRECT MERCURY ANALYZER

    EPA Science Inventory

    Mercury is a persistent, mobile, and highly toxic pollutant. It's biogeochemistry is probably the most complex of any metal. For these reasons, the U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD), has developed a comprehensive res...

  7. On-line sample preconcentration by sweeping and poly(ethylene oxide)-mediated stacking for simultaneous analysis of nine pairs of amino acid enantiomers in capillary electrophoresis.

    PubMed

    Lin, En-Ping; Lin, Kai-Cheng; Chang, Chia-Wei; Hsieh, Ming-Mu

    2013-09-30

    This study proposes a sensitive method for the simultaneous separation and concentration of 9 pairs of amino acid enantiomers by combining poly(ethylene oxide) (PEO)-based stacking, β-cyclodextrin (β-CD)-mediated micellar electrokinetic chromatography (MEKC), and 9-fluoroenylmethyl chloroformate (FMOC) derivatization. The 9 pairs of FMOC-derivatized amino acid enantiomers were baseline separated using a discontinuous system, and the buffer vials contained a solution of 150 mM Tris-borate (TB), 12.5% (v/v) isopropanol (IPA), 0.5% (w/v) PEO, 35 mM sodium taurodeoxycholate (STDC), and 35 mM β-CD, and the capillary was filled with a solution of 1.5 M TB, 12.5% (v/v) IPA, 35 mM STDC, and 35 mM β-CD. Based on the difference in viscosity between the sample zone and PEO solution and because of the STDC sweeping, the discontinuous system effectively stacked 670 nL of the 9 pairs of FMOC-derivatized amino acid enantiomers without losing chiral resolution. Consequently, the limits of detection for the 9 pairs of FMOC-derivatized amino acid enantiomers were reduced to 40-60 nM. This method was successfully used to determine d-Tryptophan (Trp), l-Trp, d-Phenylalanine (Phe), l-Phe, d-Glutamic acid (Glu), and l-Glu in various types of beers.

  8. New pressure-assisted sweeping on-line preconcentration for polar environmentally relevant nitrosamines: Part 1. sweeping for polar compounds and application of auxiliary pressure.

    PubMed

    Modir-Rousta, Ali; Bottaro, Christina S

    2013-09-01

    Typically sweeping reversed migration EKC (RM-EKC) is used for online enrichment and separation of neutral compounds in CE, however sweeping is not usually suitable for highly polar neutral compounds due to the lack of strong interaction with micellar phase. Since acidic BGE or coated capillaries (BGE pH 2-8) are used to virtually eliminate the EOF, migration of neutral analytes is only through association with the micelles with relatively slow electrophoretic mobility. To decrease the long analysis times that result, an auxiliary pressure can be applied, which also serves to avoid the associated band broadening. In this study, we have modified a commercially available CE instrument to perform pressure-assisted sweeping. The apparatus described can be used to precisely control the application of pressure, and therefore direction and magnitude of bulk flow in the capillary. This modification allows us to employ longer capillaries and capillaries with larger internal diameter to increase the sensitivity. An optimized method was used for the analysis of a group of seven N-nitrosamines that have been widely reported in environmental samples and good concentration factors of up to 34 were achieved. When a coated capillary is employed, this method is effective even at neutral pH, making it broadly applicable. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. A Distributed System for Learning Programming On-Line

    ERIC Educational Resources Information Center

    Verdu, Elena; Regueras, Luisa M.; Verdu, Maria J.; Leal, Jose P.; de Castro, Juan P.; Queiros, Ricardo

    2012-01-01

    Several Web-based on-line judges or on-line programming trainers have been developed in order to allow students to train their programming skills. However, their pedagogical functionalities in the learning of programming have not been clearly defined. EduJudge is a project which aims to integrate the "UVA On-line Judge", an existing…

  10. On-Line Learning: One Way to Bring People Together

    ERIC Educational Resources Information Center

    Goff-Kfouri, Carol Ann

    2006-01-01

    The purpose of this study was to demonstrate the benefits of on-line learning for adult learners and to further demystify three common misconceptions concerning on-line learning: students certainly do receive support from their on-line professors, the professor is pro-active rather than passive, and students may be more motivated to learn than in…

  11. Mediterranean lifestyle: nutritional education on-line.

    PubMed

    del Balzo, V; Scanu, A; Dernini, S; Palmieri, O; Cannella, C

    2009-01-01

    Our goal is to spread on-line the Italian Weekly Pyramid, a tool designed to convey both portion size and frequency of food intake. The Pyramid is referring to the "Well-being Index" (WI) as a unit for an adequate lifestyle. The user can verify his weekly lifestyle by participating to a "game" based on food/beverages consumption and time assigned to physical activity. The site has been visited by 15920 individuals, of whom 4033 completed the game. Self-selected sample, not representative of the Italian population. The data collected included WI consumption by gender for each food group compared to WI suggested. Statistical data evaluation has been performed with the SPSS inc.13 program, without applying any statistical significance to the results. The sample showed a varied eating pattern; all the food groups were consumed almost daily, albeit in much lower quantities with regards to the suggested WI. Fruit and vegetable consumption was higher in women, while men showed a higher intake of meat and cut meats. The percentage of the participants consuming more WI with respect to the recommended amounts was very low for fruit, vegetable, pasta and bread, while was much higher as regards energy dense food.

  12. On-line upgrade of program modules

    NASA Technical Reports Server (NTRS)

    Waldrop, Raymond S.; Volz, Richard A.; Smith, Gary W.; Holzbacher-Valero, A. A.; Goldsack, S. J.

    1993-01-01

    This paper presents a taxonomy of problems that must be solved in order to achieve on-line upgradability of long-lived programs, and presents a solution to the fundamental problems in the taxonomy. The solutions are based upon AdaPT, a set of language extensions designed to aid in the distribution of a single Ada program. AdaPT introduces three major units, the public, the partition, and the node. Publics are primarily used to share type information. Partitions are the basic units of distribution while nodes are used to control the configuration of the program. Nodes and partitions can be created dynamically via the allocator. A node-level routine controls the replacement process. The controlling node creates a new instance of the routine being replaced; the run-time system must ensure that the new instance is the updated one. Once access to the new version has been established, all further calls to the module are redirected to the new version and the caller is informed of the change so that it may make subsequent calls directly. When a module is being upgraded, there is a transition period during which both the old and new versions are present. We require that clients of a potentially replaceable module 'check in' with the controlling node. The controlling node keeps track of the number of clients that have been redirected to the replacement. When all have been redirected, the old version can be deallocated.

  13. Development of a portable preconcentrator/ion mobility spectrometer system for the trace detection of narcotics

    SciTech Connect

    Parmeter, J.E.; Custer, C.A.

    1997-08-01

    This project was supported by LDRD funding for the development and preliminary testing of a portable narcotics detection system. The system developed combines a commercial trace detector known as an ion mobility spectrometer (IMS) with a preconcentrator originally designed by Department 5848 for the collection of explosives molecules. The detector and preconcentrator were combined along with all necessary accessories onto a push cart, thus yielding a fully portable detection unit. Preliminary testing with both explosives and narcotics molecules shown that the system is operational, and that it can successfully detect drugs as marijuana, methamphetamine (speed), and cocaine based on their characteristics IMS signatures.

  14. Methane preconcentration in a microtrap using multiwalled carbon nanotubes as sorbents.

    PubMed

    Saridara, Chutarat; Ragunath, Smruti; Pu, Yong; Mitra, Somenath

    2010-09-10

    The GC monitoring of green house gases is a challenging task because the concentration of organic species such as methane are relatively low (ppm to ppb) and their analysis requires some level of preconcentration. Since methane is highly volatile, it is not easily retained on conventional sorbents. In this paper we present multiwalled carbon nanotubes (MWNTs) as an effective sorbent for a microtrap designed for methane preconcentration. Its performance was compared to other commercially available carbon based sorbents, and it was found to be the most effective sorbent in terms of breakthrough volume and enthalpy of adsorption.

  15. Enhanced preconcentration of selected chlorofluorocarbons on multiwalled carbon nanotubes with polar functionalities.

    PubMed

    Saridara, Chutarat; Hussain, Chaudhery Mustansar; Ragunath, Smruti; Mitra, Somenath

    2015-02-01

    Chromatographic monitoring of chlorofluorocarbons in air requires the preconcentration of these highly volatile species. In this paper, we present functionalized multiwalled carbon nanotubes as effective sorbents for a microtrap designed for chlorofluorocarbons preconcentration. Among the commercial carbons and carbon nanotubes studied, functionalization via carboxylation and propyl amine was most effective for dichlorofluoromethane and trichlorofluoromethane (Freon 11), which were selected as representative chlorofluorocarbons. The results show that carbon nanotubes functionalized with a polar groups led to as much as a 300% increase in breakthrough volume and the desorption bandwidth was reduced by 2.5 times.

  16. Determination of microcontaminants in sediments by on-line solid-phase extraction-gas chromatography-mass spectrometry.

    PubMed

    Slobodník, J; Ramalho, S; van Baar, B L; Louter, A J; Brinkman, U A

    2000-11-01

    Two simple and straightforward analytical procedures for the screening of sediment samples are reported. They involve extraction with ethyl acetate or methanol and subsequent analysis by means of gas chromatography-mass spectrometry (GC-MS) using large-volume injection (LVI) or solid-phase extraction (SPE). The latter, which was originally developed for the analysis of aqueous samples, can be used without any modification. In general, 10 ml of organic solvent were added to 2 g of sediment, and the mixture was shaken and allowed to stand overnight. The methanolic extracts were then diluted in water and subjected to preconcentration and analysis using on-line SPE-GC-MS. The ethyl acetate extracts were injected directly into the GC using LVI. Both methods were used for the detection and identification of microcontaminants during a monitoring study of the river Nitra (Slovak Republic). They included polyaromatic hydrocarbons (PAHs), chlorofluorohydrocarbons, alkoxylated and alkylated phenols and benzothiazole derivatives. Semi-quantitative profiles of the contaminants were constructed and provisionally interpreted. The results indicate that SPE-GC-MS, and also LVI-GC-MS, have good potential for a rapid screening of sediment samples and the identification of microcontaminants. The analytical procedures pose no problems, and the on-line set-up is user-friendly.

  17. Condensed Phase Membrane Introduction Mass Spectrometry with Direct Electron Ionization: On-line Measurement of PAHs in Complex Aqueous Samples

    NASA Astrophysics Data System (ADS)

    Termopoli, Veronica; Famiglini, Giorgio; Palma, Pierangela; Cappiello, Achille; Vandergrift, Gregory W.; Krogh, Erik T.; Gill, Chris G.

    2016-02-01

    Polycyclic aromatic hydrocarbons (PAHs) are USEPA regulated priority pollutants. Their low aqueous solubility requires very sensitive analytical methods for their detection, typically involving preconcentration steps. Presented is the first demonstrated `proof of concept' use of condensed phase membrane introduction mass spectrometry (CP-MIMS) coupled with direct liquid electron ionization (DEI) for the direct, on-line measurement of PAHs in aqueous samples. DEI is very well suited for the ionization of PAHs and other nonpolar compounds, and is not significantly influenced by the co-elution of matrix components. Linear calibration data for low ppb levels of aqueous naphthalene, anthracene, and pyrene is demonstrated, with measured detection limits of 4 ppb. Analytical response times (t10%-90% signal rise) ranged from 2.8 min for naphthalene to 4.7 min for pyrene. Both intra- and interday reproducibility has been assessed (<3% and 5% RSD, respectively). Direct measurements of ppb level PAHs spiked in a variety of real, complex environmental sample matrices is examined, including natural waters, sea waters, and a hydrocarbon extraction production waste water sample. For these spiked, complex samples, direct PAH measurement by CP-MIMS-DEI yielded minimal signal suppression from sample matrix effects (81%-104%). We demonstrate the use of this analytical approach to directly monitor real-time changes in aqueous PAH concentrations with potential applications for continuous on-line monitoring strategies and binding/adsorption studies in heterogeneous samples.

  18. On-line purge and trap gas chromatography for monitoring of trihalomethanes in drinking water distribution systems.

    PubMed

    Brown, Michael A; Miller, Sarah; Emmert, Gary L

    2007-06-05

    A method using an automated on-line purge and trap gas chromatograph with a dry electrolytic conductivity detector (DELCD) has been developed for monitoring four regulated trihalomethanes in drinking water distribution systems. This analyzer samples trihalomethanes from drinking water by pervaporation through a silicone capillary membrane contained within a gas extraction cell (GEC) followed by preconcentration using an adsorbent trap. Trihalomethanes are subsequently desorbed from the trap onto a capillary column, separated and detected. The analyzer operates in real-time, samples directly from the drinking water distribution system and is fully automated. The optimization, operation, and evaluation of the analyzer and method are discussed. Method detection limits (MDL) are less than 1.0 microg L(-1) with acceptable estimates for accuracy, and precision. The results from two on-line monitoring studies in chlorinated and chloraminated distribution systems are presented. The performance of the method is compared directly to United Stated Environmental Protection Agency Method 502.2 and shows a very slight, but acceptable bias.

  19. On-line SPE sample treatment as a tool for method automatization and detection limits reduction: Quantification of 25-hydroxyvitamin D3/D2.

    PubMed

    Palaiogiannis, Dimitrios; Bekou, Evangelia; Pazaitou-Panayiotou, Kalliopi; Samanidou, Victoria; Tsakalof, Andreas

    2017-02-01

    The development and approbation of new, automated UHPLC-DAD method for the quantification of 25-hydroxyvitamin D3/D2 (25OH-D3/D2) metabolites in plasma/serum for the evaluation of patient's vitamin D status are presented. The method was developed on the Ultimate 3000 UHPLC dual gradient system supplied with the on-line SPE-concentration column coupled through six port switching valve to analytical column. This configuration and materials selected enable large volume sample injection (500μL) and on-line sample preconcentration, clean up and subsequent selective metabolites transfer onto the analytical column. The new method abrogates main conventional time consuming and error source off-line steps of analysis and thus simplifies analysis. The large volume injection increases the sensitivity of instrumental analysis by about ten-fold on-line pre-concentration of metabolites. The instrument response is linear (R>0.99) in the investigated concentration range 10-100ngmL(-1) which covers all the possible vitamin D status from serious deficiency (<12ngmL(-1)) to excess. The method detection limits (S/N=3) are LOD (25OH-D3)=0.94ngmL(-1) and LOD (25OH-D2)=2.4ngmL(-1). The method performance was assessed with the use of certified reference samples and perfect agreement between certified and measured values is demonstrated. The method was applied to human samples previously analyzed for total vitamin D by Competitive Protein-binding assay and findings of the two methods are compared.

  20. On-line evaluation of multiloop digital controller performance

    NASA Technical Reports Server (NTRS)

    Wieseman, Carol D.

    1993-01-01

    The purpose of this presentation is to inform the Guidance and Control community of capabilities which were developed by the Aeroservoelasticity Branch to evaluate the performance of multivariable control laws, on-line, during wind-tunnel testing. The capabilities are generic enough to be useful for all kinds of on-line analyses involving multivariable control in experimental testing. Consequently, it was decided to present this material at this workshop even though it has been presented elsewhere. Topics covered include: essential on-line analysis requirements; on-line analysis capabilities; on-line analysis software; frequency domain procedures; controller performance evaluation frequency-domain flutter suppression; and plant determination.

  1. Organosilica composite for preconcentration of phenolic compounds from aqueous solutions.

    PubMed

    Zaitsev, V N; Khalaf, V A; Zaitseva, G N

    2008-06-01

    A new adsorbent is proposed for the solid-phase extraction of phenol and 1-naphthol from polluted water. The adsorbent (TX-SiO(2)) is an organosilica composite made from a bifunctional immobilized layer comprising a major fraction (91%) of hydrophilic diol groups and minor fraction (9%) of the amphiphilic long-chain nonionic surfactant Triton X-100 (polyoxyethylated isooctylphenol) (TX). Under static conditions phenol was quantitatively extracted onto TX-SiO(2) in the form of a 4-nitrophenylazophenolate ion associate with cetyltrimethylammonium bromide. The capacity of TX-SiO(2) for phenol is 2.4 mg g(-1) with distribution coefficients up to 3.4 x 10(4) mL g(-1); corresponding data for 1-naphthol are 1.5 mg g(-1) and 3 x 10(3) mL g(-1). The distribution coefficient does not change significantly for solution volumes of 0.025-0.5 L and adsorbent mass less than 0.03 g; 1-90 microg analyte can be easily eluted by 1-3 mL acetonitrile with an overall recovery of 98.2% and 78.3% for phenol and 1-naphthol, respectively. Linear correlation between acetonitrile solution absorbance (A(540)) and phenol concentration (C) in water was found according to the equation A(540) = (6 +/- 1) x 10(-2) + (0.9 +/- 0.1) C (micromol L(-1)) with a detection range from 1 x 10(-8) mol L(-1) (0.9 microL g(-1)) to 2 x 10(-7) mol L(-1) (19 microL g(-1)), a limit of quantification of 1 microL g(-1) (preconcentration factor 125), correlation coefficient of 0.936, and relative standard deviation of 2.5%. A solid-phase colorimetric method was developed for quantitative determination of 1-naphthol on adsorbent phase using scanner technology and RGB numerical analysis. The detection limit of 1-naphthol with this method is 6 microL g(-1) while the quantification limit is 20 microL g(-1). A test system was developed for naked eye monitoring of 1-naphthol impurities in water. The proposed test kit allows one to observe changes in the adsorbent color when 1-naphthol concentration in water is 0.08-3.2 mL g

  2. The use of selective adsorbents in capillary electrophoresis-mass spectrometry for analyte preconcentration and microreactions: a powerful three-dimensional tool for multiple chemical and biological applications.

    PubMed

    Guzman, N A; Stubbs, R J

    2001-10-01

    Much attention has recently been directed to the development and application of online sample preconcentration and microreactions in capillary electrophoresis using selective adsorbents based on chemical or biological specificity. The basic principle involves two interacting chemical or biological systems with high selectivity and affinity for each other. These molecular interactions in nature usually involve noncovalent and reversible chemical processes. Properly bound to a solid support, an "affinity ligand" can selectively adsorb a "target analyte" found in a simple or complex mixture at a wide range of concentrations. As a result, the isolated analyte is enriched and highly purified. When this affinity technique, allowing noncovalent chemical interactions and biochemical reactions to occur, is coupled on-line to high-resolution capillary electrophoresis and mass spectrometry, a powerful tool of chemical and biological information is created. This paper describes the concept of biological recognition and affinity interaction on-line with high-resolution separation, the fabrication of an "analyte concentrator-microreactor", optimization conditions of adsorption and desorption, the coupling to mass spectrometry, and various applications of clinical and pharmaceutical interest.

  3. EOS ODL Metadata On-line Viewer

    NASA Astrophysics Data System (ADS)

    Yang, J.; Rabi, M.; Bane, B.; Ullman, R.

    2002-12-01

    We have recently developed and deployed an EOS ODL metadata on-line viewer. The EOS ODL metadata viewer is a web server that takes: 1) an EOS metadata file in Object Description Language (ODL), 2) parameters, such as which metadata to view and what style of display to use, and returns an HTML or XML document displaying the requested metadata in the requested style. This tool is developed to address widespread complaints by science community that the EOS Data and Information System (EOSDIS) metadata files in ODL are difficult to read by allowing users to upload and view an ODL metadata file in different styles using a web browser. Users have the selection to view all the metadata or part of the metadata, such as Collection metadata, Granule metadata, or Unsupported Metadata. Choices of display styles include 1) Web: a mouseable display with tabs and turn-down menus, 2) Outline: Formatted and colored text, suitable for printing, 3) Generic: Simple indented text, a direct representation of the underlying ODL metadata, and 4) None: No stylesheet is applied and the XML generated by the converter is returned directly. Not all display styles are implemented for all the metadata choices. For example, Web style is only implemented for Collection and Granule metadata groups with known attribute fields, but not for Unsupported, Other, and All metadata. The overall strategy of the ODL viewer is to transform an ODL metadata file to a viewable HTML in two steps. The first step is to convert the ODL metadata file to an XML using a Java-based parser/translator called ODL2XML. The second step is to transform the XML to an HTML using stylesheets. Both operations are done on the server side. This allows a lot of flexibility in the final result, and is very portable cross-platform. Perl CGI behind the Apache web server is used to run the Java ODL2XML, and then run the results through an XSLT processor. The EOS ODL viewer can be accessed from either a PC or a Mac using Internet

  4. A lab-on-a-chip for monolith-based preconcentration and electrophoresis separation of phosphopeptides.

    PubMed

    Araya-Farias, Monica; Dziomba, Szymon; Carbonnier, Benjamin; Guerrouache, Mohamed; Ayed, Ichraf; Aboud, Nacera; Taverna, Myriam; Tran, N Thuy

    2017-01-26

    A microdevice combining online preconcentration and separation of phosphopeptides was developed in a glass microchip. An ethylene glycol methacrylate phosphate (EGMP), acrylamide (AM) and bisacrylamide (BAA) based monolith was synthesized within microchannels through a photo-driven process. Morphological investigations revealed a homogeneous monolithic structure composed of uniform nodules (∼0.8 μm), with a large pore volume (0.62 cm(3) g(-1)) and sufficiently high specific surface area (34.1 m(2) g(-1)). These features make the monolith particularly interesting for preconcentration purposes. Immobilization of Zr(4+) ions on the phosphate groups present at the poly(EGMP-co-AM-co-BAA) monolith surface leads to immobilized metal affinity chromatography support. This monolith-Zr(4+) showed a great capacity to capture phosphopeptides. Successful preconcentration and separation of a mixture of ERK2 derived peptides differing only by their phosphorylation degree and sites could be achieved with signal enhancement factors between 340 and 910 after only 7 min of preconcentration. This integrated microdevice represents a novel approach for phosphoproteomic applications.

  5. Column preconcentration of lead in aqueous solution with macroporous epoxy resin-based polymer monolithic matrix.

    PubMed

    Wang, Sui; Zhang, Ruifeng

    2006-08-11

    The objective of this article was to investigate the feasibility of epoxy resin-based monoliths prepared by stepwise polymerization and column preconcentration of metal ions using large-scale monolithic matrix. A novel macroporous polymer monolith matrix was prepared from epoxy resin (EP) and ethylenediamine (EDA) and pore-forming reagent (polyethylene glycol, PEG-1000) by in situ step-addition polymerization. The morphology of the resulting polymer monolith was characterized by scanning electron microscopy (SEM). A solid-phase extraction (SPE) cartridge prepared from a simple glass-tube was used for the preconcentration and determination of Pb(II) combined with flame atomic absorption spectroscopy (FAAS). The characteristics of the monoliths for the extraction of Pb(II) in aqueous solution were investigated. The experimental results showed that trace Pb(II) ions could be quantitatively preconcentrated in the pH range of 4.0-9.0 with recoveries of >95%. The maximum static adsorption capacity of the monolith adsorbent was 106.8 mg g(-1). The column was eluted by 1.0 mol L(-1) HNO3 and recovery of Pb(II) was more than 97%. Moreover, the polymer monolith adsorbent shows superior reusability and stability. The precision and the accuracy of the proposed procedure were satisfactory by analyzing a standard reference material and three natural water samples. It was shown that the EP-EDA monolith was suitable for the preconcentration of environmental Pb(II) as an ion-selective SPE adsorbent.

  6. Paper-based flow fractionation system for preconcentration and field-flow fractionation.

    NASA Astrophysics Data System (ADS)

    Hong, Seokbin; Kwak, Rhokyun; Kim, Wonjung

    2015-11-01

    We present a novel paper-based flow fractionation system for preconcentration and field-flow fractionation. The paper fluidic system consisting of a straight channel connected with expansion regions can generate a fluid flow with a constant flow rate for 10 min without any external pumping devices. The flow bifurcates with a fraction ratio of up to 30 depending on the control parameters of the channel geometry. Utilizing this simple paper-based bifurcation system, we developed a continuous-flow preconcentrator and a field-flow fractionator on a paper platform. Our experimental results show that the continuous-flow preconcentrator can produce a 33-fold enrichment of the ion concentration and that the flow fractionation system successfully separates the charged dyes. Our study suggests simple, cheap ways to construct preconcentration and field-flow fractionation systems for paper-based microfluidic diagnostic devices. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIP) (NRF-2015R1A2A2A04006181).

  7. Specific-lon electrode determinations of sulfide preconcentrated from San Francisco Bay waters

    USGS Publications Warehouse

    Vivit, D.V.; Ball, J.W.; Jenne, E.A.

    1984-01-01

    Measurements of low-level dissolved-sulfide concentrations in estuarine water from San Francisco Bay have been made using the sulfide-specific electrode after preservation, separation, and preconcentration of the sulfide species. The separation and preconcentration were acheived by coprecipitation of ZnS with Zn(OH)2 followed by collection and dissolution of the precipitate, giving concentration factors up to 160-fold Preconcentration provided sulfide solutions that were adequately measurable within the practical working range of the specific-ion electrode The sulfide detection limit with the preconcentration step is 0 02 ??g/l Spike recoveries in the range of 81 to 10 1% have been achieved for laboratory-prepared samples having S2- concentrations as low as 0 6 ??g/l and 84 to 100% for an estuarine sample spiked in the field with 2 ??g/l (S(-II) Positive correlations have been found between dissolved S(-II) concentrations and concentrations of dissolved Cd, Cu, and Ni, negative correlations have been found between bisulfide (HS-) activity and activities of Cd2+, Cu2+, and Ag+ species ?? 1984 Springer-Verlag New York Inc.

  8. A simplified method for capillary embedment into microfluidic devices - exemplified by sol-gel-based preconcentration.

    PubMed

    Thorslund, Sara; Johannesson, Nina; Nikolajeff, Fredrik; Bergquist, Jonas

    2007-12-01

    We here describe an alternative method of embedding functionalized capillaries into microdevices fabricated in PDMS. The capillaries have square-shaped outer dimensions and fit into elastic PDMS channel networks of similar dimensions. By modifying the capillary off-chip, the technique makes it possible to integrate a new chip function without risking contamination of already existing chemically patterned areas because of new reagent solutions. Leak-free insertion of these capillaries has earlier been reported, where a thin layer of uncured PDMS bonded the capillary to the microchannel and the lid structure. In this new approach, oxygen plasma is used to bond the square capillary to the PDMS, eliminating the risk of clogging the microsystem with uncured prepolymer. The new embedding technique was exemplified and evaluated by inserting a square capillary piece containing monolithic sol-gel for sample preconcentration application. The assembled microdevice was run with mass spectrometric detection, showing that peptides were preconcentrated without leakage from either the sol-gel itself or around the inserted capillary. Repeated preconcentration runs showed migration times better than 3% for all peptides. We believe that the presented microchip assembling technique greatly simplifies the insertion of functionalized capillary pieces, e.g., an initial preconcentrator to a PDMS device containing other downstream modules.

  9. Preconcentration and inductively coupled plasma mass spectrometric determination of lanthanides in natural and sea waters

    SciTech Connect

    Murty, D.S.R.; Chakrapani, G.; Mahalingam, T.R.

    1996-09-01

    Rare earth elements are an extremely coherent group, so that their relative abundance can be used to deduce their sources in sedimentary deposits. Also the data can be utilized to understand marine geochemistry. Hence the preconcentration of REE including Y and Sc has been studied on activated carbon (AC). Since this is the first time that sorption of REE on AC is reported, all experimental parameters have been optimized. The optimum pH is found to be between 5 to 7. Above pH 7 and below pH 5, the sorption on AC is not quantitative. Studies on the effect of weight of carbon indicated that 0.5 g of AC is adequate for quantitative sorption of REE. The REE from AC after filtration and washing are desorbed by boiling for 10 minutes with 25 ml of 2.46 M nitric acid. The REE are preconcentrated from two liters of sample solution to 5 ml, this making the effective preconcentration factor of 400. The concentration of REE in preconcentrated sample solution volume are about 10 times their detection limits by ICP-MS.

  10. PRECONCENTRATION OF ALIPHATIC AMINES FROM WATER DETERMINED BY CAPILLARY ELECTROPHORESIS WITH INDIRECT UV DETECTION

    EPA Science Inventory

    Preconcentration methodology based on adsorption chromatographies for enriching aliphatic amines (c1 to C4 substituted primary, secondary, and tertiary) and alkanolamines in water was studied by free zone capillary electrophoresis (CZE)with indirect UV detection. The solid-phase ...

  11. Pre-binding dynamic range and sensitivity enhancement for immuno-sensors using nanofluidic preconcentrator

    PubMed Central

    Wang, Ying-Chih; Han, Jongyoon

    2008-01-01

    Almost all immuno-biosensors are inherently limited by the quality of antibodies available for the target molecule, and obtaining a highly sensitive antibody for a given target molecule is a challenge. We describe a highly efficient and flexible way to enhance immunoassay detection sensitivity and binding kinetics using a nanofluidic based electrokinetic preconcentrator. The device is a microfluidic integration of charge-based biomolecule concentrator and a bead-based immunoassay. Because the preconcentrator can increase the local biomolecule concentration by many orders of magnitude, it gives the immuno-sensor better sensitivity and faster binding kinetics. With a 30 min preconcentration, we were able to enhance the immunoassay sensitivity (with molecular background) by more than 500 fold from higher 50 pM to the sub 100 fM range. Moreover, by adjusting the preconcentration time, we can switch the detection range of the given bead-based assay (from 10–10,000 ng/ml to 0.01–10,000 ng/ml) to have a broader dynamic range of detection. As the system can enhance both detection sensitivity and dynamic range, it can be used to address the most critical detection issues in the detection of common disease biomarkers. PMID:18305855

  12. PRECONCENTRATION OF ALIPHATIC AMINES FROM WATER DETERMINED BY CAPILLARY ELECTROPHORESIS WITH INDIRECT UV DETECTION

    EPA Science Inventory

    Preconcentration methodology based on adsorption chromatographies for enriching aliphatic amines (c1 to C4 substituted primary, secondary, and tertiary) and alkanolamines in water was studied by free zone capillary electrophoresis (CZE)with indirect UV detection. The solid-phase ...

  13. Effect of thermal desorption kinetics on vapor injection peak irregularities by a microscale gas chromatography preconcentrator.

    PubMed

    Seo, Jung Hwan; Liu, Jing; Fan, Xudong; Kurabayashi, Katsuo

    2012-08-07

    Microscale gas chromatography (μGC) is an emerging analytical technique for in situ analysis and on-site monitoring of volatile organic compounds (VOCs) in moderately complex mixtures. One of the critical subcomponents in a μGC system is a microfabricated preconcentrator (μ-preconcentrator), which enables detection of compounds existing in indoor/ambient air at low (~sub ppb) concentrations by enhancing their signals. The prevailing notion is that elution peak broadening and tailing phenomena resulting from undesirable conditions of a microfabricated separation column (μ-column) are the primary sources of poor chromatographic resolution. However, previous experimental results indicate that the resolution degradation still remains observed for a μ-column integrated with other μGC subcomponents even after setting optimal separation conditions. In this work, we obtain the evidence that the unoptimized μ-preconcentrator vapor release/injection performance significantly contributes to decrease the fidelity of μGC analysis using our state-of-the-art passive preconcentrator microdevice. The vapor release/injection performance is highly affected by the kinetics of the thermal desorption of compounds trapped in the microdevice. Decreasing the heating rate by 20% from the optimal rate of 90 °Cs(-1) causes a 340% increase in peak tailing as well as 70% peak broadening (30% peak height reduction) to the microscale vapor injection process.

  14. Real-time dual-loop electric current measurement for label-free nanofluidic preconcentration chip.

    PubMed

    Chung, Pei-Shan; Fan, Yu-Jui; Sheen, Horn-Jiunn; Tian, Wei-Cheng

    2015-01-07

    An electrokinetic trapping (EKT)-based nanofluidic preconcentration device with the capability of label-free monitoring trapped biomolecules through real-time dual-loop electric current measurement was demonstrated. Universal current-voltage (I-V) curves of EKT-based preconcentration devices, consisting of two microchannels connected by ion-selective channels, are presented for functional validation and optimal operation; universal onset current curves indicating the appearance of the EKT mechanism serve as a confirmation of the concentrating action. The EKT mechanism and the dissimilarity in the current curves related to the volume flow rate (Q), diffusion coefficient (D), and diffusion layer (DL) thickness were explained by a control volume model with a five-stage preconcentration process. Different behaviors of the trapped molecular plug were categorized based on four modes associated with different degrees of electroosmotic instability (EOI). A label-free approach to preconcentrating (bio)molecules and monitoring the multibehavior molecular plug was demonstrated through real-time electric current monitoring, rather than through the use of microscope images.

  15. Application of a metal ion-imprinted polymer based on salen-Cu complex to flow injection preconcentration and FAAS determination of copper.

    PubMed

    Walas, Stanisław; Tobiasz, Anna; Gawin, Marta; Trzewik, Bartosz; Strojny, Marcin; Mrowiec, Halina

    2008-06-30

    A new Cu(II)-imprinted polymer (Cu-IIP) for preconcentration of copper by liquid-solid extraction via flow injection technique has been proposed. Cu-IIP was obtained by copolymerization of salen-Cu(II) complex with styrene and divinylbenzene using suspension polymerization technique. Granules fraction of 60-80 microm in diameter was used as a microcolumn packing. Cu(II) sorption was proved to be the most effective from solutions of pH 7, whereas similar elution effectiveness was observed when applying as eluents hydrochloric or nitric acid in the concentration range of 0.5-10% (v/v). The system exhibited good long-term stability and acid resistance. Batch sorbent capacity was found to be 0.11 mmol g(-1) of a dry polymer. Enrichment factor (EF) for 30 s loading time was 16. Preconcentration of Cu(II) and potentially interfering metal ions is strongly pH dependent. Examination of Cu(II) sorption in the presence of Pb(II), Cd(II), Zn(II) and Ag(I) showed significant influence of cadmium and zinc ions only and that was for the interferent concentrations above 0.5 mg L(-1) (Cu-IIP mass of ca. 35 mg). The interference effect was reduced with the sorbent mass increase. Fe(III) and Mn(II) ions, present in treated tap water in relatively high concentrations, did not interfere. Effective pH adjusting of the loaded solution in on-line mode, when applying diluted Clark-Lubs buffering solution, allowed accurate copper determination in tap water (compared to graphite furnace atomic absorption spectrometry, GFAAS) using standard addition or combination calibration method.

  16. Determination of inorganic selenium species in water and garlic samples with on-line ionic liquid dispersive microextraction and electrothermal atomic absorption spectrometry.

    PubMed

    Martinis, Estefanía M; Escudero, Leticia B; Berton, Paula; Monasterio, Romina P; Filippini, María F; Wuilloud, Rodolfo G

    2011-09-30

    A non-chromatographic separation and preconcentration method for Se species determination based on the use of an on-line ionic liquid (IL) dispersive microextraction system coupled to electrothermal atomic absorption spectrometry (ETAAS) is proposed. Retention and separation of the IL phase was achieved with a Florisil(®)-packed microcolumn after dispersive liquid-liquid microextraction (DLLME) with tetradecyl(trihexyl)phosphonium chloride IL (CYPHOS(®) IL 101). Selenite [Se(IV)] species was selectively separated by forming Se-ammonium pyrrolidine dithiocarbamate (Se-APDC) complex followed by extraction with CYPHOS(®) IL 101. The methodology was highly selective towards Se(IV), while selenate [Se(VI)] was reduced and then indirectly determined. Several factors influencing the efficiency of the preconcentration technique, such as APDC concentration, sample volume, extractant phase volume, type of eluent, elution flow rate, etc., have been investigated in detail. The limit of detection (LOD) was 15 ng L(-1) and the relative standard deviation (RSD) for 10 replicates at 0.5 μg L(-1) Se concentration was 5.1%, calculated with peak heights. The calibration graph was linear and a correlation coefficient of 0.9993 was achieved. The method was successfully employed for Se speciation studies in garlic extracts and water samples. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. DOE-EPRI On-Line Monitoring Implementation Guidelines

    SciTech Connect

    E. Davis, R. Bickford

    2003-01-02

    Industry and EPRI experience at several plants has shown on-line monitoring to be very effective in identifying out-of-calibration instrument channels or indications of equipment-degradation problems. The EPRI implementation project for on-line monitoring has demonstrated the feasability of on-line monitoring at several participating nuclear plants. The results have been very enouraging, and substantial progress is anticipated in the coming years.

  18. MSFIA-LOV system for (226)Ra isolation and pre-concentration from water samples previous radiometric detection.

    PubMed

    Rodríguez, Rogelio; Borràs, Antoni; Leal, Luz; Cerdà, Víctor; Ferrer, Laura

    2016-03-10

    An automatic system based on multisyringe flow injection analysis (MSFIA) and lab-on-valve (LOV) flow techniques for separation and pre-concentration of (226)Ra from drinking and natural water samples has been developed. The analytical protocol combines two different procedures: the Ra adsorption on MnO2 and the BaSO4 co-precipitation, achieving more selectivity especially in water samples with low radium levels. Radium is adsorbed on MnO2 deposited on macroporous of bead cellulose. Then, it is eluted with hydroxylamine to transform insoluble MnO2 to soluble Mn(II) thus freeing Ra, which is then coprecipitated with BaSO4. The (226)Ra can be directly detected in off-line mode using a low background proportional counter (LBPC) or through a liquid scintillation counter (LSC), after performing an on-line coprecipitate dissolution. Thus, the versatility of the proposed system allows the selection of the radiometric detection technique depending on the detector availability or the required response efficiency (sample number vs. response time and limit of detection). The MSFIA-LOV system improves the precision (1.7% RSD), and the extraction frequency (up to 3 h(-1)). Besides, it has been satisfactorily applied to different types of water matrices (tap, mineral, well and sea water). The (226)Ra minimum detectable activities (LSC: 0.004 Bq L(-1); LBPC: 0.02 Bq L(-1)) attained by this system allow to reach the guidance values proposed by the relevant international agencies e.g. WHO, EPA and EC. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. MULTIELEMENT SOLID PHASE PRECONCENTRATION USING A CHELATING RESIN OF STYRENE DIVINYLBENZENE COPOLYMER AND APPLICATION TO ANALYSIS OF SEAWATER AND FISH OTOLITHS BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY (ICP�MS)

    PubMed Central

    Zereen, Fahmida; Yilmaz, Vedat; Arslan, Zikri

    2013-01-01

    A new chelating resin has been synthesized by immobilizing 4–(2–thiazolylazo) resorcinol (TAR) onto styrene divinlybenzene copolymer and examined for on-line solid phase extraction/preconcentration of Cd, Co, Cu, Ni, Pb and Zn in seawater and fish otoliths for determination by inductively plasma mass spectrometry (ICP-MS). A volume of 5.0 mL sample solution was loaded onto the mini column of TAR immobilized resin at 2.0 mL min−1 via a sequential injection system. The optimum pH for multielement preconcentration was around pH 5.5. Recoveries were better than 96% in artificial seawater. Elution was achieved with 1.0 mL of 0.75 mol L−1 HNO3. The resin possesses large sorption capacity ranging from 82.0 µmol g−1 for Pb to 319 µmol g−1 for Cu. The detection limits (3s) varied between 0.0016 µg L−1 (Cd) and to 0.015 µg L−1 (Zn) for preconcentration of 5.0 mL blank solutions (pH 5.5). Relative standard deviation (RSD)for three replicate runs was between 0.3% (Cd) and 6% (Zn) at 1.0 µg L−1 level. The procedure was validated by analysis of Nearshore Seawater certified reference material (CASS–4), and then successfully applied to the determination of the trace elements in fish otoliths (CRM 22) and in coastal seawater and estuarine water samples. PMID:24976635

  20. Dynamic layer-by-layer self-assembly of multi-walled carbon nanotubes on quartz wool for on-line separation of lysozyme in egg white.

    PubMed

    Du, Zhuo; Zhang, Suling; Zhou, Chanyuan; Liu, Miao; Li, Gongke

    2012-05-30

    The multi-walled carbon nanotubes (MWNTs) coated quartz wool (MWNTs/QW) prepared by dynamic layer-by-layer self-assembly was used as solid-phase extraction (SPE) absorbent for on-line separation and preconcentration of lysozyme in egg white. The coating procedures were performed continuously in a flow system operated by a set of sequential injection devices. The quartz wool was placed in a microcolumn forming a loose packing to guarantee the minimized flow impedance and the intimate contact between proteins and absorbent surface. Various parameters affecting SPE efficiency including the volume, pH, ionic strength and flow rate of sample and eluent were systematically studied. The feasibility of the proposed method was validated by successfully applied to the separation of lysozyme in egg white.

  1. Determination of cadmium in alcohol fuel using Moringa oleifera seeds as a biosorbent in an on-line system coupled to FAAS.

    PubMed

    Alves, Vanessa Nunes; Mosquetta, Rafael; Coelho, Nívia Maria Melo; Bianchin, Joyce Nunes; Di Pietro Roux, Kalya Cravo; Martendal, Edmar; Carasek, Eduardo

    2010-01-15

    In this study a new method for determination of cadmium in alcohol fuel using Moringa oleifera seeds as a biosorbent in an on-line preconcentration system coupled to flame atomic absorption spectrometry (FAAS) was developed. Flow and chemical variables of the proposed system were optimized through multivariate designs. The limit of detection for cadmium was 5.50microg L(-1) and the precision was below 2.3% (35.0microg L(-1), n=9). The analytical curve was linear from 5 to 150microg L(-1), with a correlation coefficient of 0.9993. The developed method was successfully applied to spiked alcohol fuel, and accuracy was assessed through recovery tests, with recovery ranging from 97.50 to 100%.

  2. On-Line Administrative Information Systems: A Case Study.

    ERIC Educational Resources Information Center

    Sire, Paul W.

    A case study approach is used to document the on-line information system developed by the Office of Management Information and Computing at the University of Vermont. Stanford University's Project INFO On-Line Administration Information System, OASIS, was chosen as a model. The administrative system is one of two on campus, the other designed for…

  3. On-Line Course Development: Engaging and Retaining Students

    ERIC Educational Resources Information Center

    Bruster, Benita G.

    2015-01-01

    As the number of on-line classes and the demand for on-line education continues to sky-rocket, it is critical that course developers and university faculty have the skills to effectively design curricula, to develop engaging learning opportunities, and to create responsive courses that meet individual student needs. This paper details three…

  4. On-Line Distance Learning: A Model for Developing Countries.

    ERIC Educational Resources Information Center

    Khan, Abdul W.

    2000-01-01

    Discusses issues related to open and distance-learning (ODL) in developing countries, using the virtual campus initiative of the Indira Gandhi National Open University (India) as an example and model of on-line program delivery and on-line, for-profit telelearning centers. Suggests strategies to enable open and distance-learning institutions to…

  5. Evidence on the Effectiveness of On-Line Homework

    ERIC Educational Resources Information Center

    Dillard-Eggers, Jane; Wooten, Tommy; Childs, Brad; Coker, John

    2008-01-01

    The purpose of this research is to evaluate the impact and effectiveness of on-line homework in principles of accounting classes. We surveyed students to determine their degree of satisfaction with on-line homework and their perceptions about its effectiveness in enhancing their learning. We also gathered data to determine the extent of online…

  6. On-line characterization of a hybridoma cell culture process.

    PubMed

    Zhou, W; Hu, W S

    1994-06-20

    The on-line determination of the physiological state of a cell culture process requires reliable on-line measurements of various parameters and calculations of specific rates from these measurements. The cell concentration of a hybridoma culture was estimated on-line by measuring optical density (OD) with a laser turbidity probe. The oxygen uptake rate (OUR) was determined by monitoring dynamically dissolved oxygen concentration profiles and closing oxygen balances in the culture. The base addition for neutralizing lactate produced by cells was also monitored on-line via a balance. Using OD and OUR measurements, the specific growth and specific oxygen consumption rates were determined on-line. By combining predetermined stoichiometric relationships among oxygen and glucose consumption and lactate production, the specific glucose consumption and lactate production rates were also calculated on-line. Using these on-line measurements and calculations, the hybridoma culture process was characterized on-line by identifying the physiological states. They will also facilitate the implementation of nutrient feeding strategies for fed-batch and perfusion cultures. (c) 1994 John Wiley & Sons, Inc.

  7. Evidence on the Effectiveness of On-Line Homework

    ERIC Educational Resources Information Center

    Dillard-Eggers, Jane; Wooten, Tommy; Childs, Brad; Coker, John

    2008-01-01

    The purpose of this research is to evaluate the impact and effectiveness of on-line homework in principles of accounting classes. We surveyed students to determine their degree of satisfaction with on-line homework and their perceptions about its effectiveness in enhancing their learning. We also gathered data to determine the extent of online…

  8. On-line Performance Assessment Using Rating Scales.

    ERIC Educational Resources Information Center

    Stahl, John; And Others

    On-line performance assessment was developed to maximize the usefulness of performance assessment and to minimize the time and labor costs incurred. This paper reports on the development of an on-line performance assessment instrument, focusing on the establishment and validation of the scoring rubric and its implementation in the Rasch model, the…

  9. Are On-Line Data Bases in Your Library's Future?

    ERIC Educational Resources Information Center

    Deacon, Jim

    1983-01-01

    THE FOLLOWING IS THE FULL TEXT OF THIS DOCUMENT: Today there are over 900 on-line data banks available for public access. Most microcomputers can use them through the aid of a modem and communication program. Major public information utilities that offer access to these on-line data bases are growing and expanding. The Source, a data base utility…

  10. Blogs and Wikis: Environments for On-Line Collaboration.

    ERIC Educational Resources Information Center

    Goodwin-Jones, Bob

    2003-01-01

    Discusses two recent innovations made available via the Internet that are useful to language educators: blogs and wikis. Blogs are on-line journals that offer opportunities for collaborative use. They are easily linked and cross-linked, thus creating larger on-line communities. Wikis feature a loosely structured set of pages, linked in multiple…

  11. On-Line Distance Learning: A Model for Developing Countries.

    ERIC Educational Resources Information Center

    Khan, Abdul W.

    2000-01-01

    Discusses issues related to open and distance-learning (ODL) in developing countries, using the virtual campus initiative of the Indira Gandhi National Open University (India) as an example and model of on-line program delivery and on-line, for-profit telelearning centers. Suggests strategies to enable open and distance-learning institutions to…

  12. System Requirements for On-Line and Batch Retrieval.

    ERIC Educational Resources Information Center

    American Society for Information Science, Washington, DC. Special Interest Group on Computerized Retrieval Services.

    Three papers on system requirements for on-line and batch retrieval presented at the American Society for Information Science (ASIS) annual meeting are included here. At G.D. Searle, data for records related to pharmacology screening are used in a batch system, and an on-line system is used to search information on mutagenic, carcinogenic, and…

  13. Are On-Line Data Bases in Your Library's Future?

    ERIC Educational Resources Information Center

    Deacon, Jim

    1983-01-01

    THE FOLLOWING IS THE FULL TEXT OF THIS DOCUMENT: Today there are over 900 on-line data banks available for public access. Most microcomputers can use them through the aid of a modem and communication program. Major public information utilities that offer access to these on-line data bases are growing and expanding. The Source, a data base utility…

  14. 45 CFR 502.8 - Documents on-line.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Documents on-line. 502.8 Section 502.8 Public Welfare Regulations Relating to Public Welfare (Continued) FOREIGN CLAIMS SETTLEMENT COMMISSION OF THE... § 502.8 Documents on-line. Commission documents available in electronic format may be accessed via the...

  15. Linking Trajectories: On-Line Learning and Intercultural Exchanges

    ERIC Educational Resources Information Center

    Levinson, Nanette; Davidson, Kaitlin E.

    2015-01-01

    There has been tremendous growth both in study abroad and intercultural exchange options in the United States and also in on-line learning options in higher education. Reviewing 91 cross-cultural experiences with at least one type of formal on-line component, this paper provides an overview and categorization of these offerings as well as a…

  16. On-Line Information Retrieval Using Associative Indexing. Final Report.

    ERIC Educational Resources Information Center

    Borko, Harold; And Others

    Experiments were performed to determine the feasibility of using ALCAPP as one form of on-line dialogue. Assuming the ALCAPP (Automatic List Classification and Profile Production) system is in an on-line mode, investigations of those parameters which could affect its stability and reliability were conducted. Fifty-two full test documents were used…

  17. System Requirements for On-Line and Batch Retrieval.

    ERIC Educational Resources Information Center

    American Society for Information Science, Washington, DC. Special Interest Group on Computerized Retrieval Services.

    Three papers on system requirements for on-line and batch retrieval presented at the American Society for Information Science (ASIS) annual meeting are included here. At G.D. Searle, data for records related to pharmacology screening are used in a batch system, and an on-line system is used to search information on mutagenic, carcinogenic, and…

  18. On-Line and Off-Line Assessment of Metacognition

    ERIC Educational Resources Information Center

    Saraç, Seda; Karakelle, Sema

    2012-01-01

    The study investigates the interrelationships between different on-line and off-line measures for assessing metacognition. The participants were 47 fifth grade elementary students. Metacognition was assessed through two off-line and two on-line measures. The off-line measures consisted of a teacher rating scale and a self-report questionnaire. The…

  19. Electrokinetic sample preconcentration and hydrodynamic sample injection for microchip electrophoresis using a pneumatic microvalve.

    PubMed

    Cong, Yongzheng; Katipamula, Shanta; Geng, Tao; Prost, Spencer A; Tang, Keqi; Kelly, Ryan T

    2016-02-01

    A microfluidic platform was developed to perform online electrokinetic sample preconcentration and rapid hydrodynamic sample injection for zone electrophoresis using a single microvalve. The polydimethylsiloxane microchip comprises a separation channel, a side channel for sample introduction, and a control channel which is used as a pneumatic microvalve aligned at the intersection of the two flow channels. The closed microvalve, created by multilayer soft lithography, serves as a nanochannel preconcentrator under an applied electric potential, enabling current to pass through while preventing bulk flow. Once analytes are concentrated, the valve is briefly opened and the stacked sample is pressure injected into the separation channel for electrophoretic separation. Fluorescently labeled peptides were enriched by a factor of ∼450 in 230 s. This method enables both rapid analyte concentration and controlled injection volume for high sensitivity, high-resolution CE.

  20. Integration of nanoporous membranes for sample filtration/preconcentration in microchip electrophoresis.

    PubMed

    Long, Zhicheng; Liu, Dayu; Ye, Nannan; Qin, Jianhua; Lin, Bingcheng

    2006-12-01

    Microfluidic devices integrating membrane-based sample preparation with electrophoretic separation are demonstrated. These multilayer devices consist of 10 nm pore diameter membranes sandwiched between two layers of PDMS substrates with embedded microchannels. Because of the membrane isolation, material exchange between two fluidic layers can be precisely controlled by applied voltages. More importantly, since only small molecules can pass through the nanopores, the integrated membrane can serve as a filter or a concentrator prior to microchip electrophoresis under different design and operation modes. As a filter, they can be used for separation and selective injection of small analytes from sample matrix. This has been effectively applied in rapid determination of reduced glutathione in human plasma and red blood cells without any off-chip deproteinization procedure. Alternatively, in the concentrator mode, they can be used for online purification and preconcentration of macromolecules, which was illustrated by removing primers and preconcentrating the product DNA from a PCR product mixture.

  1. [Water matrices samples: pre-concentration problems and methodologies for ecotoxicological assessment of fresh waters].

    PubMed

    Galassi, Silvana

    2005-01-01

    Biological monitoring and ecotoxicological investigation are research methods for water quality assessment included in the Italian regulation in force (DL.vo 152/99). Biological monitoring must be applied in every case while ecotoxicological investigation is not mandatory. While extended biotic index application methodologies are standardized, pre-concentration sample procedures applied for ecotoxicological investigation are not, because they are applied as research only. Pre-concentration for organic micro-pollutants can be carried out both by means of organic solvents and through SPE (solid phase extraction), being the latter more advantageous than the former. In any case, an intercalibration exercise should be undertaken to assess the applicability of the proposed procedure to all the national territory.

  2. Microwave acid digestion and preconcentration neutron activation analysis of biological and diet samples for iodine.

    PubMed

    Rao, R R; Chatt, A

    1991-07-01

    A simple preconcentration neutron activation analysis (PNAA) method has been developed for the determination of low levels of iodine in biological and nutritional materials. The method involves dissolution of the samples by microwave digestion in the presence of acids in closed Teflon bombs and preconcentration of total iodine, after reduction to iodide with hydrazine sulfate, by coprecipitation with bismuth sulfide. The effects of different factors such as acidity, time for complete precipitation, and concentrations of bismuth, sulfide, and diverse ions on the quantitative recovery of iodide have been studied. The absolute detection limit of the PNAA method is 5 ng of iodine. Precision of measurement, expressed in terms of relative standard deviation, is about 5% at 100 ppb and 10% at 20 ppb levels of iodine. The PNAA method has been applied to several biological reference materials and total diet samples.

  3. From carbon nanostructures to high-performance sorbents for chromatographic separation and preconcentration

    NASA Astrophysics Data System (ADS)

    Postnov, V. N.; Rodinkov, O. V.; Moskvin, L. N.; Novikov, A. G.; Bugaichenko, A. S.; Krokhina, O. A.

    2016-02-01

    Information on carbon nanostructures (fullerenes, nanotubes, graphene, nanodiamond and nanodispersed active carbon) used to develop high-performance sorbents of organics and heavy metal ions from aqueous solutions is collected and analyzed. The advantages in the synthesis of hybrid carbon nanostructures and the possibilities of surface modification of these systems in order to carry out fast sorption pre-concentration are considered. Prospects for application of these materials in sorption technologies and analytical chemistry are discussed. The bibliography includes 364 references.

  4. On-Line Allocation Of Robot Resources To Task Plans

    NASA Astrophysics Data System (ADS)

    Lyons, Damian M.

    1989-02-01

    In this paper, I present an approach to representing plans that make on-line decisions about resource allocation. An on-line decision is the evaluation of a conditional expression involving sensory information as the plan is being executed. I use a plan representation called 7ZS10'1 1,12that has been especially designed for the domain of robot programming, and in particular, for the problem of on-line decisions. The resource allocation example is based on the robot assembly cell architecture outlined by Venkataraman and Lyons16. I begin by setting forth a definition of on-line decision making and some arguments as to why this form of decision making is important and useful. To set the context for the resource allocation example, I take some care in categorizing the types of on-line decision making and the approaches adopted by other workers so far. In particular, I justify a plan-based approach to the study of on-line decision making. From that, the focus shifts to one type of decision making: on-line allocation of robot resources to task plans. Robot resources are the physical manipulators (grippers, wrists, arms, feeders, etc) that are available to carry out the task. I formulate the assembly cell architecture of Venkataraman and Lyons16 as an R.S plan schema, and show how the on-line allocation specified in that architecture can be implemented. Finally, I show how considering the on-line allocation of logical resources, that is a physical resource plus some model information, can be used as a non-traditional approach to some problems in robot task planning.

  5. Pre-concentration and determination of tartrazine dye from aqueous solutions using modified cellulose nanosponges.

    PubMed

    Shiralipour, Roohollah; Larki, Arash

    2017-01-01

    In this study, a new absorbent based on cellulose nanosponges modified with methyltrioctylammonium chloride (aliquat 336) was prepared and used for pre-concentration, removal and determination of tartrazine dye, using UV-vis spectrophotometry. This adsorbent was fully characterized using various instrumental techniques such as SEM, FTIR and XRD spectra. The pre-concentration and removal procedures were studied in column and batch modes, respectively. The effects of parameters such as pH of the aqueous medium, methyltrioctylammounium chloride dose, adsorbent amount, desorbing conditions and interfering ions on the adsorption of tartrazine were investigated and optimized. The fitting experimental data with conventional isotherm models revealed that the adsorption followed the Brunauer-Emmett-Teller (BET) model and the maximum adsorption capacity for tartrazine was 180mg/g with modified nanosponges. Under the optimized conditions, the calibration curve was linear over the range of 2-300ng/mL and the limit of detection was 0.15ng/mL. The relative standard deviation (RSD) for 20 and 100ng/mL of tartrazine were 3.1% and 1.5%, respectively. The proposed method was applied for pre-concentration and determination of tartrazine dye in different water samples.

  6. Optimization of antibody-conjugated magnetic nanoparticles for target preconcentration and immunoassays

    PubMed Central

    Smith, Joshua E.; Sapsford, Kim E.; Tan, Weihong; Ligler, Frances S.

    2013-01-01

    Biosensors based on antibody recognition have a wide range of monitoring applications that apply to clinical, environmental, homeland security, and food problems. In an effort to improve the limit of detection of the Naval Research Laboratory (NRL) Array Biosensor, magnetic nanoparticles (MNPs) were designed and tested using a fluorescence-based array biosensor. The MNPs were coated with the fluorescently labeled protein, AlexaFluor647–chicken IgG (Alexa647–chick IgG). Antibody-labeled MNPs (Alexa647–chick–MNPs) were used to preconcentrate the target via magnetic separation and as the tracer to demonstrate binding to slides modified with anti-chicken IgG as a capture agent. A full optimization study of the antibody-modified MNPs and their use in the biosensor was performed. This investigation looked at the Alexa647–chick–MNP composition, MNP surface modifications, target preconcentration conditions, and the effect that magnetic extraction has on the Alexa647–chick–MNP binding with the array surface. The results demonstrate the impact of magnetic extraction using the MNPs labeled with fluorescent proteins both for target preconcentration and for subsequent integration into immunoassays performed under flow conditions for enhanced signal generation. PMID:21078282

  7. The determination of hazardous air pollutants with a built-in preconcentrator and capillary GC

    SciTech Connect

    Kirshen, N.; Almasi, E.

    1994-12-31

    Under the 1990 Clean Air Act Amendments industries identified as major sources of hazardous air pollutants must meet Maximum Achievable Control Technology standards within a certain time frame. A hazardous air pollutant GC system has been configured with a new built-in sample preconcentration trap (SPT) and associated valving capable of preconcentrating air samples of variable volumes. Since the preconcentrator is built into the GC, the system has a small footprint, simple interfacing, and control from one PC. The air sample is drawn either from a canister or directly from the ambient air through SPT adsorbent trap. The adsorbent trap is cooled to initial conditions using the option of a cryo or non-cryo technique. Following trapping, the air toxics are quickly desorbed with the fast heating (40 C/sec) SPT to a wide bore capillary column with detection by FID, PID, ECD, or a combination of detectors. No column oven cryogenics are required. Optimization of the trapping and chromatographic parameters has been performed using a TO-14 air standard. The results of these studies and a description of the integrated system will be presented.

  8. Concurrent DNA Preconcentration and Separation in Bipolar Electrode-Based Microfluidic Device

    PubMed Central

    Song, Hongjun; Wang, Yi; Garson, Charles; Pant, Kapil

    2015-01-01

    This paper presents a bipolar electrode (BPE) device in a microfluidic dual-channel design for concurrent preconcentration and separation of composite DNA containing samples. The novelty of the present effort relies on the combination of BPE-induced ion concentration polarization (ICP) and end-labeled free-solution electrophoresis (ELFSE). The ion concentration polarization effect arising from the faradaic reaction on the BPE is utilized to exert opposing electrophoretic and electroosmotic forces on the DNA samples. Meanwhile, end-labeled free-solution electrophoresis alters the mass-charge ratio to enable simultaneous DNA separation in free solution. The microfluidic device was fabricated using standard and soft lithography techniques to form gold-on-glass electrode capped with a PDMS microfluidic channel. Experimental testing with various DNA samples was carried out over a range of applied electric field. Concentration ratios up to 285× within 5 minutes for a 102-mer DNA, and concurrent preconcentration and free-solution separation of binary mixture of free and bound 102-mer DNA within 6 minutes was demonstrated. The effect of applied electric field was also interrogated with respect to pertinent performance metrics of preconcentration and separation. PMID:26005497

  9. Optimization of antibody-conjugated magnetic nanoparticles for target preconcentration and immunoassays.

    PubMed

    Smith, Joshua E; Sapsford, Kim E; Tan, Weihong; Ligler, Frances S

    2011-03-01

    Biosensors based on antibody recognition have a wide range of monitoring applications that apply to clinical, environmental, homeland security, and food problems. In an effort to improve the limit of detection of the Naval Research Laboratory (NRL) Array Biosensor, magnetic nanoparticles (MNPs) were designed and tested using a fluorescence-based array biosensor. The MNPs were coated with the fluorescently labeled protein, AlexaFluor647-chicken IgG (Alexa647-chick IgG). Antibody-labeled MNPs (Alexa647-chick-MNPs) were used to preconcentrate the target via magnetic separation and as the tracer to demonstrate binding to slides modified with anti-chicken IgG as a capture agent. A full optimization study of the antibody-modified MNPs and their use in the biosensor was performed. This investigation looked at the Alexa647-chick-MNP composition, MNP surface modifications, target preconcentration conditions, and the effect that magnetic extraction has on the Alexa647-chick-MNP binding with the array surface. The results demonstrate the impact of magnetic extraction using the MNPs labeled with fluorescent proteins both for target preconcentration and for subsequent integration into immunoassays performed under flow conditions for enhanced signal generation.

  10. Solid-nanoemulsion preconcentrate for oral delivery of paclitaxel: formulation design, biodistribution, and γ scintigraphy imaging.

    PubMed

    Ahmad, Javed; Mir, Showkat R; Kohli, Kanchan; Chuttani, Krishna; Mishra, Anil K; Panda, A K; Amin, Saima

    2014-01-01

    Aim of present study was to develop a solid nanoemulsion preconcentrate of paclitaxel (PAC) using oil [propylene glycol monocaprylate/glycerol monooleate, 4:1 w/w], surfactant [polyoxyethylene 20 sorbitan monooleate/polyoxyl 15 hydroxystearate, 1:1 w/w], and cosurfactant [diethylene glycol monoethyl ether/polyethylene glycol 300, 1:1 w/w] to form stable nanocarrier. The prepared formulation was characterized for droplet size, polydispersity index, and zeta potential. Transmission electron microscopy (TEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to assess surface morphology and drug encapsulation and its integrity. Cumulative drug release of prepared formulation through dialysis bag and permeability coefficient through everted gut sac were found to be remarkably higher than the pure drug suspension and commercial intravenous product (Intaxel), respectively. Solid nanoemulsion preconcentrate of PAC exhibited strong inhibitory effect on proliferation of MCF-7 cells in MTT assay. In vivo systemic exposure of prepared formulation through oral administration was comparable to that of Intaxel in γ scintigraphy imaging. Our findings suggest that the prepared solid nanoemulsion preconcentrate can be used as an effective oral solid dosage form to improve dissolution and bioavailability of PAC.

  11. Solid-Nanoemulsion Preconcentrate for Oral Delivery of Paclitaxel: Formulation Design, Biodistribution, and γ Scintigraphy Imaging

    PubMed Central

    Ahmad, Javed; Mir, Showkat R.; Kohli, Kanchan; Chuttani, Krishna; Mishra, Anil K.; Panda, A. K.

    2014-01-01

    Aim of present study was to develop a solid nanoemulsion preconcentrate of paclitaxel (PAC) using oil [propylene glycol monocaprylate/glycerol monooleate, 4 : 1 w/w], surfactant [polyoxyethylene 20 sorbitan monooleate/polyoxyl 15 hydroxystearate, 1 : 1 w/w], and cosurfactant [diethylene glycol monoethyl ether/polyethylene glycol 300, 1 : 1 w/w] to form stable nanocarrier. The prepared formulation was characterized for droplet size, polydispersity index, and zeta potential. Transmission electron microscopy (TEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to assess surface morphology and drug encapsulation and its integrity. Cumulative drug release of prepared formulation through dialysis bag and permeability coefficient through everted gut sac were found to be remarkably higher than the pure drug suspension and commercial intravenous product (Intaxel), respectively. Solid nanoemulsion preconcentrate of PAC exhibited strong inhibitory effect on proliferation of MCF-7 cells in MTT assay. In vivo systemic exposure of prepared formulation through oral administration was comparable to that of Intaxel in γ scintigraphy imaging. Our findings suggest that the prepared solid nanoemulsion preconcentrate can be used as an effective oral solid dosage form to improve dissolution and bioavailability of PAC. PMID:25114933

  12. On-Line Construction of Parameterized Suffix Trees

    NASA Astrophysics Data System (ADS)

    Lee, Taehyung; Na, Joong Chae; Park, Kunsoo

    We consider on-line construction of a suffix tree for a parameterized string, where we always have the suffix tree of the input string read so far. This situation often arises from source code management systems where, for example, a source code repository is gradually increasing in its size as users commit new codes into the repository day by day. We present an on-line algorithm which constructs a parameterized suffix tree in randomized O(n) time, where n is the length of the input string. Our algorithm is the first randomized linear time algorithm for the on-line construction problem.

  13. Clinical benefits of predilution on-line hemodiafiltration.

    PubMed

    Tsuchida, Kenji; Minakuchi, Jun

    2013-01-01

    There are two types of hemodiafiltration (HDF) treatments, predilution and postdilution. In Japan, clinical doctors have been using the on-line HDF treatment for renal replacement therapy for 20 years. However, this treatment is not popular in Japan because it has not been recognized by the government. Generally, the advantage of postdilution HDF over predilution HDF resides in the fact that it removes low-weight molecular proteins (LWMPs) and protein-binding uremic toxin. Thus, postdilution on-line HDF has been widely used in the world, but in Japan predilution on line-HDF has been the preferred treatment. There are several reasons why predilution on-line HDF has been the preferred treatment in Japan. Predilution on-line HDF is superior to postdilution on-line HDF in removing LWMPs and protein-binding uremic toxin, for example p-cresol and homocysteine. In addition, there are several reports on the biocompatibilities in predilution on-line HDF. Predilution on-line HDF is associated with reduced shear stress, and the synthesis of cytokine and cellular adhesion molecules. Moreover, with predilution on-line HDF/hemofiltration, blood pressure remains stable during treatment. In Japan, over 90% of dialysis patients have been receiving hemodialysis (HD) therapy with the ultra-high flux dialysis membrane. These ultra-high flux dialysis membranes achieve β2-microglobulin clearance rates of >50 ml/min. In addition, these membranes have the same power as postdilution HDF because they allow automatic internal filtration. Thus, in spite of HD treatment, as a result, the effect is the same as with postdilution HDF treatment. There have been small and retrospective studies on predilution on-line HDF, and we must use a hemodiafilter during the on-line HDF treatment. However, the hemodiafilter has been unsuccessful in reaching the LWMP removal rates which we demand. And the most important point is to carry out a prospective multicenter randomized controlled trial of predilution

  14. An on-line stacking capillary electrophoresis method for the analysis of Δ(9)-tetrahydrocannabinol and its metabolites.

    PubMed

    Cheng, Hui-Ling; Tsai, Yi-Hsuan; Hsu, Wan-Ling; Lin, Yi-Hui

    2015-12-24

    The objective of this study was to establish a practical and reliable analytical method for monitoring trace amounts of Δ(9)-tetrahydrocannabinol (THC) and its metabolites in biological samples. A novel on-line preconcentration capillary electrophoresis method combining large volume sample injection, anion selective exhaustive injection and sweeping was developed to enhance analytical sensitivity. A background buffer composed with 30mM phosphate buffer (pH 2.5) containing 40% methanol and 100mM SDS was used to suppress the electroosmotic flow of the uncoated fused silica capillary (40cm×50μm i.d.). High conductivity buffer (200mM phosphate, pH 2.5) was injected for analyte accumulation. The samples, prepared in phosphate buffer or Tris buffer, were introduced by hydrodynamic injection and electrokinetic injection. After sweeping, the separation was performed in micellar electrokinetic chromatography (MEKC) mode at -15kV. During the method validation, the coefficient of determination of the regression curve was measured at greater than 0.993, and the relative standard deviation and relative error were lower than 11.06% and 9.24%, respectively. Under optimized conditions, an improvement of up to 2000-fold higher sensitivity was achieved. This method was applied to the analysis of urine samples, indicating that it could be satisfactorily utilized in the toxicological and clinical monitoring of cannabis.

  15. Recent Advances in On-Line Methods Based on Extraction for Speciation Analysis of Chromium in Environmental Matrices.

    PubMed

    Trzonkowska, Laura; Leśniewska, Barbara; Godlewska-Żyłkiewicz, Beata

    2016-07-03

    The biological activity of Cr(III) and Cr(VI) species, their chemical behavior, and toxic effects are dissimilar. The speciation analysis of Cr(III) and Cr(VI) in environmental matrices is then of great importance and much research has been devoted to this area. This review presents recent developments in on-line speciation analysis of chromium in such samples. Flow systems have proved to be excellent tools for automation of sample pretreatment, separation/preconcentration of chromium species, and their detection by various instrumental techniques. Analytical strategies used in chromium speciation analysis discussed in this review are divided into categories based on selective extraction/separation of chromium species on solid sorbents and liquid-liquid extraction of chromium species. The most popular strategy is that based on solid-phase extraction. Therefore, this review shows the potential of novel materials designed and used for selective binding of chromium species. The progress in miniaturization of measurement systems is also presented.

  16. Flow injection on-line solid phase extraction for ultra-trace lead screening with hydride generation atomic fluorescence spectrometry.

    PubMed

    Wan, Zhuo; Xu, Zhangrun; Wang, Jianhua

    2006-01-01

    A flow injection (FI) on-line solid phase extraction (SPE) procedure for ultra-trace lead separation and preconcentration was developed, followed by hydride generation and atomic fluorescence spectrometric (AFS) detection. Lead is retained on an iminodiacetate chelating resin packed microcolumn, and is afterward eluted with 2.5% (v/v) hydrochloric acid to facilitate the hydride generation by reaction with alkaline tetrahydroborate solution with 1% (m/v) potassium ferricyanide as an oxidizing (or sensitizing) reagent. The hydride was separated from the reaction medium in the gas-liquid separator and swept into the atomizer for quantification. The chemical variables and the FI flow parameters were carefully optimized. With a sample loading volume of 4.8 ml, quantitative retention of lead was obtained, along with an enrichment factor of 11.3 and a sampling frequency of 50 h(-1). A detection limit of 4 ng l(-1), defined as 3 times the blank standard deviation (3 sigma), was achieved along with a RSD value of 1.6% at the 0.4 microg l(-1) level. The procedure was validated by determining lead contents in two certified reference materials, and its practical applicability was further demonstrated by analysing a variety of biological and environmental samples.

  17. Preparing Students for Assessment in the On-Line Class.

    ERIC Educational Resources Information Center

    Ford, Michele L.

    2002-01-01

    Advises professors with limited technological experience on how to use features of their existing computer networks to communicate assessment expectations to their on-line students. Explains how e-mail and Web postings can serve this purpose. (EV)

  18. SOLAR: A Storage and On-Line Automatic Retrieval System

    ERIC Educational Resources Information Center

    Mitchell, P. C.; And Others

    1973-01-01

    SOLAR is an interactive Storage and On-Line Automatic Retrieval system which is operational at Washington State University. It can run continuously with virtually any mix of tasks in a general purpose computing environment. (22 references) (Author)

  19. Preparing Students for Assessment in the On-Line Class.

    ERIC Educational Resources Information Center

    Ford, Michele L.

    2002-01-01

    Advises professors with limited technological experience on how to use features of their existing computer networks to communicate assessment expectations to their on-line students. Explains how e-mail and Web postings can serve this purpose. (EV)

  20. Planning an Integrated On-Line Library system (IOLS)

    DTIC Science & Technology

    1989-03-01

    by block number 1 Field Group Subgroup IOLS, NCTIS, library, automation , analysis, cost, implementation 19 Abstract (continue on reverse if necessary...and identify by block number) Requirements for an Integrated On-line Library System (IOLS) to automate the acquisitions, cataloging and circulation...ABSTRACT Requirements for an Integrated On-line Library System (IOLS) to automate the acqui- sitions, cataloging and circulation functions of the Dudley

  1. On-line Monitoring of Ultrasonic Polymer Chain Scission

    NASA Astrophysics Data System (ADS)

    Akyüz, Ali; Giz, Ahmet; Çatalgil-Giz, Huceste

    2007-03-01

    Poly vinyl pyrrolidone in dilute aqueous solution was subjected to ultrasonic scission. The decrease of the molecular weight was monitored by light scattering via a BIMwA molecular weight analyzer. The on-line data was compared with the theoretical models of Schmid, Malhorta, Price, Madras and Berlin, Doulah,. The models were compared on the bases of χ^2 analysis and fit quality. It is seen that on-line data can discriminate among theoretical models.

  2. Cationic surfactant-based polyfluorate salts: phase separation and analytical applications in the extraction and preconcentration of ionic species prior to liquid chromatography.

    PubMed

    Paleologos, Evangelos K

    2005-02-25

    The liquid-solid phase separation originating from the formation of cationic surfactant-based polyfluorate salts (CSBPS) has been explored for extracting and preconcentrating ionic species. Two cationic surfactants were tested; one with aliphatic hydrocarbon tail [Cetyltrimethylammonium bromide (CTAB)]and the other containing a heterocyclic ring [Hexadecylpyridinium bromide (HPyBr)]. Phase separation possibility was investigated with the use of hexafluorophosphates (PF6-) and tetrafluoroborates (BF4-). The effect of added acid, base and salt on the phase separation and analyte extraction was also investigated. In all cases the obtained phase diagrams consisted of two regions: a homogeneous liquid region and a solid-liquid region. Analytes of hydrophilic and hydrophobic nature such as amines, amino acids and organic chromophores were used as test compounds in both their anionic and cationic forms. The respective recoveries ranged from over 90% for anionic species and in the proximity of 50% for cationic species, remaining below 20% for neutral species. Extracts from alkaline aqueous and plasma samples spiked with tyrosine and phenylalanine were also subjected to HPLC separation with UV detection with satisfactory results. On line application was also enabled using a flow through-solid phase extraction-HPLC hyphenated apparatus, thus adding the element of automatization and increased reproducibility.

  3. On-line fan blade damage detection using neural networks

    NASA Astrophysics Data System (ADS)

    Oberholster, A. J.; Heyns, P. S.

    2006-01-01

    This paper presents a methodology for monitoring the on-line condition of axial-flow fan blades with the use of neural networks. In developing this methodology, the first stage was to utilise neural networks trained on features extracted from on-line blade vibration signals measured on an experimental test structure. Results from a stationary experimental modal analysis of the structure were used for identifying global blade mode shapes and their corresponding frequencies. These in turn were used to assist in identifying vibration-related features suitable for neural network training. The features were extracted from on-line blade vibration and strain signals which were measured using a number of sensors. The second stage in the development of the methodology entails utilising neural networks trained on numerical Frequency Response Function (FRF) features obtained from a Finite Element Model (FEM) of the test structure. Frequency domain features obtained from on-line experimental measurements were used to normalise the numerical FRF features prior to neural network training. Following training, the networks were tested using experimental frequency domain features. This approach makes it unnecessary to damage the structure in order to train the neural networks. The paper shows that it is possible to classify damage for several fan blades by using neural networks with on-line vibration measurements from sensors not necessarily installed on the damaged blades themselves. The significance of this is that it proves the possibility to perform on-line fan blade damage classification using less than one sensor per blade. Even more significant is the demonstration that an on-line damage detection system for a fan can be developed without having to damage the actual structure.

  4. Characterizing the Performance of a Proton-Transfer-Reaction Mass Spectrometer with a Rapid Cycling Tenax Preconcentrator

    SciTech Connect

    Garland, S.P.; Alexander, M.L.

    2006-01-01

    Volatile organic compounds (VOCs) are species of interest for atmospheric modeling, worker chemical exposure and medical studies. Sometimes the required detection limits for these compounds is below the capability of existing real-time instrumentation. Preconcentrators have been implemented as an inexpensive way to amplify chemical signals and improve detection limits. Proton-transfer-reaction mass spectrometry (PTR-MS) has been used as a tool for studying low concentrations of VOCs, but it lacks the capability to differentiate chemical signal contributions from isobaric compounds. In this work, behavior of a newly designed Tenax TA preconcentrator when coupled with a PTRMS is characterized. This novel preconcentrator design allows rapid temperature cycling, maintaining near real-time response. The preconcentrator was exposed to a sample gas of toluene in varying concentrations and loading times between and then thermally desorbed for analysis by PTR-MS. The effects of preconcentrating multiple analytes simultaneously were also investigated as well as the chromatographic effects of the preconcentrator. A linear behavior was observed when the integrated ion count rates (ICPS) from thermal desorption peaks were regressed against both varying loading times at a constant toluene concentration and varying concentrations with constant loading times. From these trends, it is possible to determine the concentration of a VOC by knowing its ICPS from thermal desorption peaks from a known preconcentration time. Peak height ion count rates representing ultimate detectability were amplified by factors up to 257 times the original signal, extending the range of the PTR-MS from 50pptv to nearly 250 parts per quadrillion. This corresponds to an ultimate sensitivity of 200 parts per quadrillion with 20 minute time resolution. Quantitative preconcentrator behavior was demonstrated using ICPS from these ion peaks and were amplified as much as 148 times their original signal. Results

  5. Ion chromatographic preconcentration of Cu and Cd from ultra-high-purity water and determination by electrothermal atomic absorption spectrometry.

    PubMed

    Scaccia, S; Zappa, G; Basili, N

    2001-04-27

    A method based on preconcentration of Cu and Cd from ultra-high-purity water by ion chromatography (IC) and determination by electrothermal atomic absorption spectrometry is described. A small low-capacity ion-exchange concentrator Dionex HPIC-CG5 and mobile phase of 3 mM pyridine-2,6-dicarboxylic acid (PDCA) are used. Water samples are loaded onto the preconcentration column at a flow-rate ranging from 1 to 3.5 ml min(-1). Large sample volumes (up to 200 ml) can be loaded onto the concentrator without losing metal ions. Elution is carried out in the reverse direction of sample loading and the volumes of effluent are as small as 0.150 and 0.200 ml for copper and cadmium, respectively. Under these conditions the preconcentrated ions coelute. The detection limits, based on the Hubaux-Vos method, for Cu using a 1300-fold preconcentration in the IC step was found to be 1 pg ml(-1), and was limited due to impurity in PDCA, while the detection limit found for Cd using a 1000-fold preconcentration was 0.02 pg ml(-1). Ultra-high-purity water produced by a Millipore system is successfully analysed by the proposed method and the content of Cu and Cd are found to lie in the range 1-10 pg ml(-1).

  6. Engagement of parents in on-line social support interventions.

    PubMed

    Paterson, Barbara L; Brewer, Joan; Stamler, Lynnette Leeseberg

    2013-04-01

    The purpose of this scoping review was to determine what the relevant research informs us about which parents of children with chronic disease and/or disability are likely to engage in an on-line social support program and why they choose to be engaged. The review included 16 peer-reviewed research reports about on-line social support offered to parents of children with chronic disease and/or disability. It was conducted using scoping review approaches recommended by H. Arskey and L. O'Malley (2005). A key finding of this review is that it appears that the development of on-line social support interventions for parents may not have integrated what is known in the field of Internet technology as necessary to engage users. This has implications for nurses wishing to provide on-line social support for parents. As well, it highlights future directions for research, including investigations of which parents are likely to engage in on-line social support interventions and the features of the intevention that will attract and sustain them as participants.

  7. Automatic On-line Solid-phase Extraction-Electrothermal Atomic Absorption Spectrometry Exploiting Sequential Injection Analysis for Trace Vanadium, Cadmium and Lead Determination in Human Urine Samples.

    PubMed

    Giakisikli, Georgia; Ayala Quezada, Alejandro; Tanaka, Junpei; Anthemidis, Aristidis N; Murakami, Hiroya; Teshima, Norio; Sakai, Tadao

    2015-01-01

    A fully automated sequential injection column preconcentration method for the on-line determination of trace vanadium, cadmium and lead in urine samples was successfully developed, utilizing electrothermal atomic absorption spectrometry (ETAAS). Polyamino-polycarboxylic acid chelating resin (Nobias chelate PA-1) packed into a handmade minicolumn was used as a sorbent material. Effective on-line retention of chelate complexes of analytes was achieved at pH 6.0, while the highest elution effectiveness was observed with 1.0 mol L(-1) HNO3 in the reverse phase. Several analytical parameters, like the sample acidity, concentration and volume of the eluent as well as the loading/elution flow rates, have been studied, regarding the efficiency of the method, providing appropriate conditions for the analysis of real samples. For a 4.5 mL sample volume, the sampling frequency was 27 h(-1). The detection limits were found to be 3.0, 0.06 and 2.0 ng L(-1) for V(V), Cd(II) and Pb(II), respectively, with the relative standard deviations ranging between 1.9 - 3.7%. The accuracy of the proposed method was evaluated by analyzing a certified reference material (Seronorm(TM) trace elements urine) and spiked urine samples.

  8. A Hybrid On-line Verification Method of Relay Setting

    NASA Astrophysics Data System (ADS)

    Gao, Wangyuan; Chen, Qing; Si, Ji; Huang, Xin

    2017-05-01

    Along with the rapid development of the power industry, grid structure gets more sophisticated. The validity and rationality of protective relaying are vital to the security of power systems. To increase the security of power systems, it is essential to verify the setting values of relays online. Traditional verification methods mainly include the comparison of protection range and the comparison of calculated setting value. To realize on-line verification, the verifying speed is the key. The verifying result of comparing protection range is accurate, but the computation burden is heavy, and the verifying speed is slow. Comparing calculated setting value is much faster, but the verifying result is conservative and inaccurate. Taking the overcurrent protection as example, this paper analyses the advantages and disadvantages of the two traditional methods above, and proposes a hybrid method of on-line verification which synthesizes the advantages of the two traditional methods. This hybrid method can meet the requirements of accurate on-line verification.

  9. Thermographic Sensing For On-Line Industrial Control

    NASA Astrophysics Data System (ADS)

    Holmsten, Dag

    1986-10-01

    It is today's emergence of thermoelectrically cooled, highly accurate infrared linescanners and imaging systems that has definitely made on-line Infraread Thermography (IRT) possible. Specifically designed for continuous use, these scanners are equipped with dedicated software capable of monitoring and controlling highly complex thermodynamic situations. This paper will outline some possible implications of using IRT on-line by describing some uses of this technology in the steel-making (hot rolling) and automotive industries (machine-vision). A warning is also expressed that IRT technology not originally designed for automated applications e.g. high resolution, imaging systems, should not be directly applied to an on-line measurement situation without having its measurement resolution, accuracy and especially its repeatability, reliably proven. Some suitable testing procedures are briefly outlined at the end of the paper.

  10. Single battery power subsystems: On-line reconditioning

    NASA Technical Reports Server (NTRS)

    Tobias, R. F.

    1996-01-01

    The effect of on-line reconditioning (deep discharge) on a single, Nickel-Hydrogen spacecraft battery in GEO and LEO is considered. A life cycle test was performed in both GEO and LEO to study the effect of reconditioning on the battery's end of discharge voltage (EODV). The results of these tests show that: LEO on-line reconditioning increased the EODV (by approximately 15 cycles to maximum EODV) and the EODV lasted for approximately 300 cycles, but GEO on-line reconditioning decreased the EODV slightly during the first six days and increases significantly after the seventh day. Based on the available data from the life cycle test, it has been concluded that a long life and stable voltage is realizable with the baseline architecture (single battery, single bus) without the need for reconditioning.

  11. Amine-functionalized mesoporous polymer as potential sorbent for nickel preconcentration from electroplating wastewater.

    PubMed

    Islam, Aminul; Zaidi, Noushi; Ahmad, Hilal; Kumar, Suneel

    2015-05-01

    In this study, mesoporous glycidyl methacrylate-divinylbenzene-based chelating resin was synthesized and grafted with diethylenetriamine through epoxy ring-opening reaction. The synthesized resin was characterized by elemental analysis, infrared spectroscopy, surface area and pore size analysis, scanning electron microscopy, energy-dispersive spectroscopy, and thermogravimetry. The resin was used for the first time as an effective sorbent for the preconcentration of nickel in electroplating wastewater samples. The analytical variables like pH, flow rate for sorption/desorption, and eluate selection were systematically investigated and optimized. The uniform and monolayer sorption behavior of resin for nickel was proved by an evident fit of the equilibrium data to a Langmuir isotherm model. Under optimized conditions, the resin was observed to show a good sorption capacity of 20.25 mg g(-1) and >96% recovery of nickel even in the presence of a large number of competitive matrix ions. Its ability to extract trace amount of nickel was exhibited by low preconcentration limit (5.9 μg L(-1)). The calibration curve was found to be linear (R(2) = 0.998) in the concentration range of 6.0-400.0 μg L(-1). Coefficient of variation of less than 5 for all the analysis indicated good reproducibility. The reliability was evaluated by the analysis of standard reference material (SRM) and recovery experiments. The applicability of the resin for the systematic preconcentration of nickel is substantiated by the analysis of electroplating wastewater and river water samples. Graphical abstract ᅟ.

  12. Simultaneous Electrodialytic Preconcentration and Speciation of Chromium(III) and Chromium(VI).

    PubMed

    Ohira, Shin-Ichi; Nakamura, Koretaka; Shelor, C Phillip; Dasgupta, Purnendu K; Toda, Kei

    2015-11-17

    Large amounts of chromium (Cr) compounds are used for manufacturing of various products and various chemical processes. Some inevitably find their way into the environment. Environmental Cr is dominantly inorganic and is either in the cationic +3 oxidation state or in the anionic oxochromium +6 oxidation state. The two differ dramatically in their implications; Cr(III) is essential to human nutrition and even sold as a supplement, while Cr(VI) is a potent carcinogen. Drinking water standards for chromium may be based on total Cr or Cr(VI) only. Thus, Cr speciation analysis is very important. Despite their high sensitivity, atomic spectrometric techniques or induction coupled plasma-mass spectrometry (ICP-MS) cannot directly differentiate the oxidation states. We present here a new electrodialytic separation concept. Sample analyte ions are quantitatively transferred via appropriately ionically functionalized dialysis membranes into individual receptors that are introduced into the ICP-MS. There was no significant conversion of Cr(VI) to Cr(III) or vice versa during the very short (6 s) separation process. Effects of salinity (up to ∼20 mM NaCl) can be eliminated with proper membrane functionalization and receptor optimization. With the ICP-MS detector we used, the limits of detection for either form of Cr was 0.1 μg/L without preconcentration. Up to 10-fold preconcentration was readily possible by increasing the donor solution flow rate relative to the acceptor solution flow rates. The proposed approach permits simultaneous matrix isolation, preconcentration, and chromium speciation.

  13. Preconcentration and Atomization of Arsane in a Dielectric Barrier Discharge with Detection by Atomic Absorption Spectrometry.

    PubMed

    Novák, Petr; Dědina, Jiří; Kratzer, Jan

    2016-06-07

    Atomization of arsane in a 17 W planar quartz dielectric barrier discharge (DBD) atomizer was optimized, and its performance was compared to that of a multiple microflame quartz tube atomizer (MMQTA) for atomic absorption spectrometry (AAS). Argon, at a flow rate of 60 mL min(-1), was the best DBD discharge gas. Free As atoms were also observed in the DBD with nitrogen, hydrogen, and helium discharge gases but not in air. A dryer tube filled with NaOH beads placed downstream from the gas-liquid separator to prevent residual aerosol and moisture transport to the atomizer was found to improve the response by 25%. Analytical figures of merit were comparable, reaching an identical sensitivity of 0.48 s ng (-1) As in both atomizers and limits of detection (LOD) of 0.15 ng mL(-1) As in MMQTA and 0.16 ng mL(-1) As in DBD, respectively. Compared to MMQTA, DBD provided 1 order of magnitude better resistance to interference from other hydride-forming elements (Sb, Se, and Bi). Atomization efficiency in DBD was estimated to be 100% of that reached in the MMQTA. A simple procedure of lossless in situ preconcentration of arsane was developed. Addition of 7 mL min(-1) O2 to the Ar plasma discharge resulted in a quantitative retention of arsane in the optical arm of the DBD atomizer. Complete analyte release and atomization was reached as soon as oxygen was switched off. Preconcentration efficiency of 100% was observed, allowing a decrease of the LOD to 0.01 ng mL(-1) As employing a 300 s preconcentration period.

  14. Development of a FI-HG-ICP-OES solid phase preconcentration system for inorganic selenium speciation in Argentinean beverages.

    PubMed

    Escudero, Luis A; Pacheco, Pablo H; Gasquez, José A; Salonia, José A

    2015-02-15

    A preconcentration system has been developed to determine inorganic selenium species. Selenium was retained by a column filled with polyvinyl chloride (PVC) with lanthanum hydroxide co-precipitation. Speciation was achieved by selective photoreduction previous Se preconcentration. The retention pH was optimized at 10.0. Two multivariate calibrations and a central composite design were employed for optimization of the system. Sample, reagents and acid flow rates are significant variables affecting the system. Employing HG-ICP-OES as detection, the optimized system reached a detection limit of 0.03μg/L, and an enhancement factor of 14875 (25 for preconcentration system, 595 for hydride generation). To verify the method' accuracy, two certified reference materials, BCR® 414 Plankton & IRMM-804 Rice Flour, were analysed. The system was applied to inorganic selenium speciation in several Argentinean beverages to estimate their selenium contribution to diet. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. On-line measurement of heat of combustion

    NASA Technical Reports Server (NTRS)

    Chaturvedi, S. K.; Chegini, H.

    1988-01-01

    An experimental method for an on-line measurement of heat of combustion of a gaseous hydrocarbon fuel mixture of unknown composition is developed. It involves combustion of a test gas with a known quantity of air to achieve a predetermined oxygen concentration level in the combustion products. This is accomplished by a feedback controller which maintains the gas volumetric flow rate at a level consistent with the desired oxygen concentration in the products. The heat of combustion is determined from a known correlation with the gas volumetric flow rate. An on-line microcomputer accesses the gas volumetric flow data, and displays the heat of combustion values at desired time intervals.

  16. On-line metrology with conoscopic holography: beyond triangulation.

    PubMed

    Alvarez, Ignacio; Enguita, Jose M; Frade, María; Marina, Jorge; Ojea, Guillermo

    2009-01-01

    On-line non-contact surface inspection with high precision is still an open problem. Laser triangulation techniques are the most common solution for this kind of systems, but there exist fundamental limitations to their applicability when high precisions, long standoffs or large apertures are needed, and when there are difficult operating conditions. Other methods are, in general, not applicable in hostile environments or inadequate for on-line measurement. In this paper we review the latest research in Conoscopic Holography, an interferometric technique that has been applied successfully in this kind of applications, ranging from submicrometric roughness measurements, to long standoff sensors for surface defect detection in steel at high temperatures.

  17. On-Line Point Positioning with Single Frame Camera Data

    DTIC Science & Technology

    1992-03-15

    AD-A248 307 --. On-line point positioning with single frame camera data DTIC FnleoS ELECTE 1b. Kersten, K. R. Holm, A. Gruen PRV (1992 Institute of...until exhiausted StCUIRITY CLSif!CATION Of THIS PAGE All othier editions are obsolext UNLSS I F ED .... . . ... On-line point positioning with single... all work undertakm in this project. Pe a .. [ -4 IOn-line point poitonng with angle frame camr daon 2. Introduction Aerotriangulation is an efficient

  18. Optimization of polyhydroxyalkanoates fermentations with on-line capacitance measurement.

    PubMed

    Li, Lan; Wang, Ze-Jian; Chen, Xue-Jun; Chu, Ju; Zhuang, Ying-Ping; Zhang, Si-Liang

    2014-03-01

    The aim of this work was to provide an effective methodology for optimization of the polyhydroxyalkanoates (PHAs) fermentation with Ralstonia eutropha by the on-line capacitance measurement. The present study found the capacitance values could reflect variations of microbial morphology and viability. Furthermore, oxygen uptake rate, specific oxygen uptake rate and specific growth rate were measured in real-time and compared with the capacitance value. In addition, a fed-batch control strategy based on the on-line capacitance measurement was proposed to improve the PHAs production by 22%. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. On-Line Bin Packing in Linear Time.

    DTIC Science & Technology

    1983-10-01

    reverse side If necesaery and identify by block number) T Ithis paper-weI!tzdy- the one-dimensional on-line bin packing problem. A list of pieces, each...of size between zero and unity are to be packl, in order of their arrival, into a minimum number of unit-capacity bins. -W present a new linear-time...analysis of the algorithm’s performance involves a novel use of weighting function: In addition, we also show that for a large class of linear-time on-line

  20. On-line access to geoscience bibliographic citations

    USGS Publications Warehouse

    Wild, Emily C.

    2012-01-01

    On-line geoscience bibliographic citations and access points to citations are exponentially increasing as commercial, non-profit, and government agencies worldwide publish materials electronically. On-line bibliographic tools capture cited works, and open access content allows for freely obtained citations and documents. For this newsletter, citations from the numerous journals and books listed in the "Recent Papers" section of the EXPLORE newsletters from 2008-2011 were used to provide freely-accessible web sites to determine the availability of bibliographic information.

  1. Carbosilane polymers with hydrogen bond acidic functionalization for chemical preconcentrator applications

    NASA Astrophysics Data System (ADS)

    Simonson, Duane L.; McGill, R. Andrew; Higgins, Bernadette A.

    2008-04-01

    Vapor collection systems, including solid phase microextraction (SPME), require the ability to selectively collect and concentrate a sample from a large volume of air. In the case of SPME, polymers are needed to adhere to the fiber for greater reproducibility and longer lasting fibers. The polymerization of carbosilanes was investigated and produced polymers with molecular weights over 500,000. This polymer class was then functionalized with hexafluoro-2-propanol (HFIP) end groups that will selectively sorb hydrogen bond basic vapors. The results of vapor testing with these polymers utilizing a variety of platforms such as preconcentrators, Surface Acoustic Wave (SAW) sensors, and microcantilevers will be discussed.

  2. Preconcentration of heavy metals in urine and quantification by inductively coupled plasma atomic emission spectrometry.

    PubMed

    López-Artíguez, M; Cameán, A; Repetto, M

    1993-01-01

    This paper describes a method for the determination of heavy metals (Co, Ni, Cu, Cd, Pb) in urine by inductively coupled plasma atomic emission spectrometry (ICP-AES). The method proposed requires purification of the samples with activated charcoal under acidic conditions before preconcentration by complexation with ammonium pyrrolidinedithiocarbamate (APDC). The formed complexes are extracted with methyl isobutyl ketone (MIBK) and the resulting residue is finally digested under acid oxidant conditions. Because of its low detection limit (below 10 micrograms/L), this procedure can be applied conveniently for toxicological diagnostic purposes.

  3. Exploration geochemical technique for the determination of preconcentrated organometallic halides by ICP-AES

    USGS Publications Warehouse

    Motooka, J.M.

    1988-01-01

    An atomic absorption extraction technique which is widely used in geochemical exploration for the determination of Ag, As, Au, Bi, Cd, Cu, Mo, Pb, Sb, and Zn has been modified and adapted to a simultaneous inductively coupled plasma-atomic emission instrument. the experimental and operating parameters are described for the preconcentration of the metals into their organometallic halides and for the determination of the metals. Lower limits of determination are equal to or improved over those for flame atomic absorption (except Au) and ICP results are very similar to the accepted AA values, with precision for the ICP data in excess of that necessary for exploration purposes.

  4. Bucknell On-Line Circulation System; A Library Staff View.

    ERIC Educational Resources Information Center

    Rivoire, Helena

    The Bucknell On-Line Circulation System (BLOCS) was designed to meet the requirements of a circulation system of the Ellen Clarke Bertrand Library of Bucknell University. The requirements for an automated system were, in sum: (1) a system whose operations were not only reliable but simple enough for student assistants (many of whom work only 10…

  5. ON-LINE TOXICITY MONITORS AND WATERSHED EARLY WARNING SYSTEMS

    EPA Science Inventory

    A Water Quality Early Warning System using On-line Toxicity Monitors (OTMs) has been deployed in the East Fork of the Little Miami River, Clermont County, OH. Living organisms have long been used to determine the toxicity of environmental samples. With advancements in electronic ...

  6. The On-Line Audit Revisited: Yale University.

    ERIC Educational Resources Information Center

    Weldon, Albert R., Jr.; And Others

    1984-01-01

    Yale University's on-line examination of accounting and administrative systems is discussed. Program goals are to review financial management systems at the university to identify weaknesses in internal controls, and to fulfill all audit requirements of federal grants and contracts. After outlining the quarterly audit cycle, advantages of the…

  7. On-Line Text Processing: Introduction and Overview.

    ERIC Educational Resources Information Center

    Walker, D.E.

    The objective of the current work program is to develop an on-line computer capability that would assist an information analyst in processing textual materials. The initial result of the work program is the design of a system for text processing and a computer implementation of a preliminary model of the system that strongly supports the validity…

  8. Developing an On-Line Interactive Health Psychology Module

    ERIC Educational Resources Information Center

    Upton, Dominic; Cooper, Carol

    2006-01-01

    On-line teaching material in health psychology was developed which ensured a range of students could access appropriate material for their course and level of study. This material has been developed around the concept of smaller "content chunks" which can be combined into whole units of learning (topics), and ultimately, a module. On the…

  9. The On-Line Audit Revisited: Yale University.

    ERIC Educational Resources Information Center

    Weldon, Albert R., Jr.; And Others

    1984-01-01

    Yale University's on-line examination of accounting and administrative systems is discussed. Program goals are to review financial management systems at the university to identify weaknesses in internal controls, and to fulfill all audit requirements of federal grants and contracts. After outlining the quarterly audit cycle, advantages of the…

  10. Section BB Hatch Coating; Framing Plan on Line C Lodging ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Section B-B Hatch Coating; Framing Plan on Line C Lodging Knees at Hatch; Elevation A-A Hull Framing; Section at Hatch Frame 36, Starboard Looking Aft; Midship Section Frame 37, Port Looking Aft - Steam Schooner WAPAMA, Kaiser Shipyard No. 3 (Shoal Point), Richmond, Contra Costa County, CA

  11. EPA'S ON-LINE CALCULATORS AND TRAINING COURSE

    EPA Science Inventory

    EPA has developed a suite of on-line calculators called "OnSite" for assessing transport of environmental contaminants int the subsurface. The calculators are available on the Internet at http://www.epa.gov/athens/onsite, and are divided into four categories: Parameter Estimate...

  12. On-line mass storage system functional design document

    NASA Technical Reports Server (NTRS)

    Earnest, D.

    1975-01-01

    A functional system definition for an on-line high density magnetic tape data storage system is provided. This system can be implemented in a multi-purpose, multi-host environment, and satisfy the requirements of economical data storage in the range of 2 to 50 billion bytes.

  13. On-Line Analysis of Southern FIA Data

    Treesearch

    Michael P. Spinney; Paul C. Van Deusen; Francis A. Roesch

    2006-01-01

    The Southern On-Line Estimator (SOLE) is a web-based FIA database analysis tool designed with an emphasis on modularity. The Java-based user interface is simple and intuitive to use and the R-based analysis engine is fast and stable. Each component of the program (data retrieval, statistical analysis and output) can be individually modified to accommodate major...

  14. Students' Off-Line and On-Line Experiences.

    ERIC Educational Resources Information Center

    Davis, Elizabeth A.; And Others

    1995-01-01

    Examines the knowledge construction processes of novice programmers using parentheses and quotes in hypermedia; identifies characteristics of successful and unsuccessful students working off- and on-line. The strategies of perceptual matching and computer feedback were used in both settings to interpret of the information presented. (Author/AEF)

  15. On-Line Learning and the Implications for School Design

    ERIC Educational Resources Information Center

    Stack, Greg

    2011-01-01

    "Disrupting Class," published in 2008, is the story of how disruptive innovation, innovation that changes the business model organizations, will fundamentally change the American school system. The book's most startling prediction is that half of all high school classes will be on-line by 2019. In considering these predictions, the author began to…

  16. Children's On-Line Processing of Scrambling in Japanese

    ERIC Educational Resources Information Center

    Suzuki, Takaaki

    2013-01-01

    This study investigates the on-line processing of scrambled sentences in Japanese by preschool children and adults using a combination of self-paced listening and speeded picture selection tasks. The effects of a filler-gap dependency, reversibility, and case markers were examined. The results show that both children and adults had difficulty in…

  17. On-Line NDE for Advanced Reactor Designs

    NASA Astrophysics Data System (ADS)

    Nakagawa, N.; Inanc, F.; Thompson, R. B.; Junker, W. R.; Ruddy, F. H.; Beatty, J. M.; Arlia, N. G.

    2003-03-01

    This expository paper introduces the concept of on-line sensor methodologies for monitoring the integrity of components in next generation power systems, and explains general benefits of the approach, while describing early conceptual developments of suitable NDE methodologies. The paper first explains the philosophy behind this approach (i.e. the design-for-inspectability concept). Specifically, we describe where and how decades of accumulated knowledge and experience in nuclear power system maintenance are utilized in Generation IV power system designs, as the designs are being actively developed, in order to advance their safety and economy. Second, we explain that Generation IV reactor design features call for the replacement of the current outage-based maintenance by on-line inspection and monitoring. Third, the model-based approach toward design and performance optimization of on-line sensor systems, using electromagnetic, ultrasonic, and radiation detectors, will be explained. Fourth, general types of NDE inspections that are considered amenable to on-line health monitoring will be listed. Fifth, we will describe specific modeling developments to be used for radiography, EMAT UT, and EC detector design studies.

  18. Holographic On-Line Learning Machine for Multicategory Classification

    NASA Astrophysics Data System (ADS)

    Paek, Eung Gi; Wullert, John R.; Patel, J. S.

    1990-07-01

    A holographic on-line learning machine that is capable of multicategory classification is described. The system exactly implements the single-layer perceptron algorithm in a fully parallel and analog fashion. The performance of the adaptive network is successfully tested for up to 24 characters with different scale and rotation. Also, a compact and robust version of the holographic learning machine is proposed.

  19. After Sundown: Adventures in On-Line Searching.

    ERIC Educational Resources Information Center

    Jordan, Kathy; Bernhardt, Frances

    1984-01-01

    Describes how two Northern Virginia Community College campuses began using the "after dark" services of DIALOG and BRS to provide their first on-line searching. Indicates that both campuses had positive experiences with these services and plan to continue their use along with the full DIALOG system in the future. (DMM)

  20. On-Line Information Retrieval as a Scientists Tool

    ERIC Educational Resources Information Center

    Barber, A. Stephanie; And Others

    1973-01-01

    The use of an on-line information retrieval system by the scientists themselves is described. MEDUSA was designed to allow physicians to interrogate the MEDLARS data base. A Brief description is given of the system and details of an experiment to test its effectiveness. (8 references) (Author)

  1. Children's On-Line Processing of Scrambling in Japanese

    ERIC Educational Resources Information Center

    Suzuki, Takaaki

    2013-01-01

    This study investigates the on-line processing of scrambled sentences in Japanese by preschool children and adults using a combination of self-paced listening and speeded picture selection tasks. The effects of a filler-gap dependency, reversibility, and case markers were examined. The results show that both children and adults had difficulty in…

  2. An Experimental On-Line Information Retrieval System.

    ERIC Educational Resources Information Center

    Cautin, Harvey; And Others

    This paper reports an experiment in on-line retrieval using man-machine dialogue on a remote console. Message editing procedures and the use of two command languages are described. The system employs a PDP-8 computer for generating, proofreading, and editing messages, and an IBM 7040 computer for information retrieval processing. The symbolic…

  3. On-Line Synthesis and Analysis by Mass Spectrometry

    ERIC Educational Resources Information Center

    Bain, Ryan M.; Pulliam, Christopher J.; Raab, Shannon A.; Cooks, R. Graham

    2015-01-01

    In this laboratory experiment, students learn how to use ESI to accelerate chemical synthesis and to couple it with on-line mass spectrometry for structural analysis. The Hantzsch synthesis of symmetric 1,4-dihydropyridines is a classic example of a one-pot reaction in which multiple intermediates can serve to indicate the progress of the reaction…

  4. English Language Education On-Line Game and Brain Connectivity

    ERIC Educational Resources Information Center

    Hong, Ji Sun; Han, Doug Hyun; Kim, Young In; Bae, Su Jin

    The HoDoo English game was developed to take advantage of the benefits attributed to on-line games while teaching English to native Korean speakers. We expected to see that the improvements in the subjects' English language abilities after playing the HoDoo English game would be associated with increased brain functional connectivity in the areas…

  5. On-Line Pesticide Training with Narrated Powerpoint Presentations

    ERIC Educational Resources Information Center

    Johnson, Steven B.

    2015-01-01

    UMaine Cooperative Extension is the primary educational delivery organization for pesticide recertification credits in Maine. Shrinking budgets and staff numbers are making traditional face-to-face delivery increasingly difficult to maintain. To address this issue, on-line pesticide applicator recertification training credits were developed. The…

  6. WMI2, the Student's On-Line Symbolic Calculator

    ERIC Educational Resources Information Center

    Kovacs, Zoltan

    2011-01-01

    Student activities focused on discovering mathematics play an important role in the teaching and learning process. WebMathematics Interactive (WMI2) was developed to offer a fast and user-friendly on-line web interface to enhance the quality of both theoretical and applied mathematics courses. For the teacher, in the classroom, it provides…

  7. On-Line Services in Medicine and Beyond

    ERIC Educational Resources Information Center

    McCarn, Davis B.; Leiter, Joseph

    1973-01-01

    Discusses the development and operation of MEDLINE which was initiated by the National Library of Medicine in 1971. This is the first generally accessible, on-line, national and international information retrieval service, and allows almost instantaneous searching of over 400,000 citations from the world's biomedical serial literature. (JR)

  8. On-line fuzzy logic control of tube bending

    NASA Astrophysics Data System (ADS)

    Lieh, Junghsen; Li, Wei Jie

    2005-11-01

    This paper describes the simulation and on-line fuzzy logic control of tube bending. By combining elasticity and plasticity theories, a conventional model was developed. The results from simulation were compared with those obtained from testing. The experimental data reveal that there exists certain level of uncertainty and nonlinearity in tube bending, and its variation could be significant. To overcome this, a on-line fuzzy logic controller with self-tuning capabilities was designed. The advantages of this on-line system are (1) its computational requirement is simple in comparison with more algorithmic-based controllers, and (2) the system does not need prior knowledge of material characteristics. The device includes an AC motor, a servo controller, a forming mechanism, a 3D optical sensor, and a microprocessor. This automated bending machine adopts primary and secondary errors between the actual response and desired output to conduct on-line rule reasoning. Results from testing show that the spring back angle can be effectively compensated by the self- tuning fuzzy system in a real-time fashion.

  9. The On-Line Processing of Unaccusativity in Greek Agrammatism

    ERIC Educational Resources Information Center

    Peristeri, Eleni; Tsimpli, Ianthi-Maria; Tsapkini, Kyrana

    2013-01-01

    We investigated the on-line processing of unaccusative and unergative sentences in a group of eight Greek-speaking individuals diagnosed with Broca aphasia and a group of language-unimpaired subjects used as the baseline. The processing of unaccusativity refers to the reactivation of the postverbal trace by retrieving the mnemonic representation…

  10. The On-Line Processing of Written Irony

    ERIC Educational Resources Information Center

    Filik, Ruth; Moxey, Linda M.

    2010-01-01

    We report an eye-tracking study in which we investigate the on-line processing of written irony. Specifically, participants' eye movements were recorded while they read sentences which were either intended ironically, or non-ironically, and subsequent text which contained pronominal reference to the ironic (or non-ironic) phrase. Results showed…

  11. On-Line Learning and the Implications for School Design

    ERIC Educational Resources Information Center

    Stack, Greg

    2011-01-01

    "Disrupting Class," published in 2008, is the story of how disruptive innovation, innovation that changes the business model organizations, will fundamentally change the American school system. The book's most startling prediction is that half of all high school classes will be on-line by 2019. In considering these predictions, the author began to…

  12. The Challenge of Developing On-Line Courses.

    ERIC Educational Resources Information Center

    Auter, Philip J.; Hanna, Michael S.

    Many challenges face the communication instructor wishing to use the Internet, the World Wide Web, and other on-line resources in the classroom; most common are questions of faculty support, facilities limitations, and student limitations. While some members of communication departments may speak glowingly about the future of the on-line…

  13. Implementation, Analysis, and Assessment of On-Line Teaching Evaluations

    NASA Astrophysics Data System (ADS)

    Artz, Jerry L.

    2005-04-01

    This two-year project involved the introduction of a new, on-line teaching evaluation that enables students to anonymously assess their teachers and courses via computer. A pilot program, during fall 2003, involved 14 faculty volunteers. Student participation was voluntary but was strongly encouraged via both student congress and the student newspaper. Resulting in moderate to strong success, the pilot program was then extended to include the entire College of Liberal Arts of Hamline University during the spring and fall of 2004. The on-line teaching-evaluation program has since been introduced into several other colleges of the University. The evaluation instrument, student compliance, analysis of data, and assessment will be discussed. Comparisons are made (1) by grade received, (2) by class standing, (3) by ethnicity, and (4) of science versus non-science courses. In addition to common questions answered by all students, the on-line form allows instructors to add course-specific questions. Additional disciplinary-breadth assessment questions were added for the fall 2004 evaluation. Noteworthy problems that resulted from the introduction of on-line teaching evaluations will be discussed along with successes.

  14. On-Line Text Processing: Introduction and Overview.

    ERIC Educational Resources Information Center

    Walker, D.E.

    The objective of the current work program is to develop an on-line computer capability that would assist an information analyst in processing textual materials. The initial result of the work program is the design of a system for text processing and a computer implementation of a preliminary model of the system that strongly supports the validity…

  15. Developing an On-Line Interactive Health Psychology Module

    ERIC Educational Resources Information Center

    Upton, Dominic; Cooper, Carol

    2006-01-01

    On-line teaching material in health psychology was developed which ensured a range of students could access appropriate material for their course and level of study. This material has been developed around the concept of smaller "content chunks" which can be combined into whole units of learning (topics), and ultimately, a module. On the…

  16. Searching CA Condensates, On-Line and Batch.

    ERIC Educational Resources Information Center

    Kaminecki, Ronald M.; And Others

    Batch mode processing is compared, using cost-effectiveness, with on-line processing for computer-aided searching of chemical abstracts. Consideration for time, need, coverage, and adaptability are found to be the criteria by which a searcher selects a method, and sometimes both methods are used. There is a tradeoff between batch mode's slower…

  17. The Nearness of You: Students & Teachers Writing On-Line.

    ERIC Educational Resources Information Center

    Edgar, Christopher, Ed.; Wood, Susan Nelson, Ed.

    This book is a guide to using new computer technologies in innovative ways to teach writing, particularly imaginative writing. The book shows how on-line technology can be a positive tool in the classroom, if the focus is on the users of the technology and the technology is integrated into the curriculum. The book is divided into five sections and…

  18. EPA'S ON-LINE CALCULATORS AND TRAINING COURSE

    EPA Science Inventory

    EPA has developed a suite of on-line calculators called "OnSite" for assessing transport of environmental contaminants int the subsurface. The calculators are available on the Internet at http://www.epa.gov/athens/onsite, and are divided into four categories: Parameter Estimate...

  19. Gender In-Difference: Rethinking Ideologies On-Line.

    ERIC Educational Resources Information Center

    Grubbs, Katherine

    On-line writing can disrupt conventions; it can challenge the way writers write in the classroom; however, after logging off, the writer re-enters the academy and its more traditional ways of inscribing student subjectivities. The question is asked if educators, when arguing for the freedom of electronic classrooms, are taking into consideration…

  20. The Transformation of Mathematics in On-Line Courses

    ERIC Educational Resources Information Center

    Borba, Marcelo C.

    2005-01-01

    This paper presents some research findings regarding the changes in the mathematics produced by mathematics teachers in on-line distance courses. Predicated on the belief that knowledge is generated by collectives of humans-with-media, and that different technologies modify the nature of the knowledge generated, we have sought to understand how…

  1. The Lesson Observation On-Line (Evidence Portfolio) Platform

    ERIC Educational Resources Information Center

    Cooper, David G.

    2015-01-01

    At a time when teacher training is being moved to school-based programmes it is important to engage in a research-informed dialogue about creating more distinctive, and cost-effective 21st century models of teacher training. Three years ago I began feasibility field testing the Lesson Observation On-line (Evidence Portfolio) Platform [LOOP]…

  2. On-Line Synthesis and Analysis by Mass Spectrometry

    ERIC Educational Resources Information Center

    Bain, Ryan M.; Pulliam, Christopher J.; Raab, Shannon A.; Cooks, R. Graham

    2015-01-01

    In this laboratory experiment, students learn how to use ESI to accelerate chemical synthesis and to couple it with on-line mass spectrometry for structural analysis. The Hantzsch synthesis of symmetric 1,4-dihydropyridines is a classic example of a one-pot reaction in which multiple intermediates can serve to indicate the progress of the reaction…

  3. On-Line Pesticide Training with Narrated Powerpoint Presentations

    ERIC Educational Resources Information Center

    Johnson, Steven B.

    2015-01-01

    UMaine Cooperative Extension is the primary educational delivery organization for pesticide recertification credits in Maine. Shrinking budgets and staff numbers are making traditional face-to-face delivery increasingly difficult to maintain. To address this issue, on-line pesticide applicator recertification training credits were developed. The…

  4. The Nearness of You: Students & Teachers Writing On-Line.

    ERIC Educational Resources Information Center

    Edgar, Christopher, Ed.; Wood, Susan Nelson, Ed.

    This book is a guide to using new computer technologies in innovative ways to teach writing, particularly imaginative writing. The book shows how on-line technology can be a positive tool in the classroom, if the focus is on the users of the technology and the technology is integrated into the curriculum. The book is divided into five sections and…

  5. ON-LINE TOXICITY MONITORS AND WATERSHED EARLY WARNING SYSTEMS

    EPA Science Inventory

    A Water Quality Early Warning System using On-line Toxicity Monitors (OTMs) has been deployed in the East Fork of the Little Miami River, Clermont County, OH. Living organisms have long been used to determine the toxicity of environmental samples. With advancements in electronic ...

  6. On-line diagnosis of sequential systems, 2

    NASA Technical Reports Server (NTRS)

    Sundstrom, R. J.

    1974-01-01

    The theory and techniques applicable to the on-line diagnosis of sequential systems, were investigated. A complete model for the study of on-line diagnosis is developed. First an appropriate class of system models is formulated which can serve as a basis for a theoretical study of on-line diagnosis. Then notions of realization, fault, fault-tolerance and diagnosability are formalized which have meaningful interpretations in the the context of on-line diagnosis. The diagnosis of systems which are structurally decomposed and are represented as a network of smaller systems is studied. The fault set considered is the set of faults which only affect one component system is the network. A characterization of those networks which can be diagnosed using a purely combinational detector is achieved. A technique is given which can be used to realize any network by a network which is diagnosable in the above sense. Limits are found on the amount of redundancy involved in any such technique.

  7. IOOS Data Portals and Uniform On-line Browse Capabilities

    NASA Astrophysics Data System (ADS)

    Howard, M.; Currier, R. D.; Kobara, S.; Gayanilo, F.

    2015-12-01

    The Gulf of Mexico Coastal Ocean Observing System Regional Association (GCOOS-RA) is one of eleven Regional Associations organized under the NOAA-led U.S. Integrated Ocean Observing System (IOOS) Program Office. Each of the RAs operate standards-based regional data portals designed to aggregate near real-time and historical observed data and modeled outputs from distributed providers and to offer these and derived products in standardized ways to a diverse set of users. The RA's portals are based on the IOOS Data and Communications Plan which describes the functional elements needed for an interoperable system. One of these elements is called "Uniform On-line Browse" which is an informational service designed primarily to visualize the inventory of a portal. An on-line browse service supports the end user's need to discover what parameters are available, to learn the spatial and temporal extend of the holdings, and to examine the character of the data (e.g, variability, gappiness, etc). These pieces of information help the end user decide if the data are fit for his/her purpose and to construct valid data requests. Note that on-line browse is a distinctly different activity than data analysis because it seeks to yield knowledge about the inventory and not about what the data mean. "Uniform" on-line browse is a service that takes advantage of the standardization of the data portal's data access points. Most portals represent station locations on a map. This is a view of the data inventory but these plots are rarely generated by pulling data through the standards-based services offered to the end users but through methods only available to the portal programmers. This work will present results of Uniform On-line browse tools developed within GCOOS-RA and their applicability to other RA portals.

  8. Sensitive ergotamine determination in pharmaceuticals and biological samples using cloud point preconcentration and spectrofluorimetric detection.

    PubMed

    Wang, Chien C; Fernández, Liliana P; Gómez, María Roxana

    2013-03-20

    A new cloud point extraction (CPE) method for ergotamine analysis using fluorimetric detection is described. Ergotamine from an aqueous solution was preconcentrated into a smaller surfactant-rich phase using nonionic surfactant polyoxyethylene(7.5)nonylphenylether (PONPE 7.5). Differently from the conventional CPE procedure in which the resulting surfactant-rich phase is diluted by a fluidificant before its analysis, in this method the fluorescence measurements were carried out directly onto the undiluted surfactant-rich phase. The high viscosity provided by the undiluted surfactant rich phase greatly improved the fluorescence emission of ergotamine, leading to a total enhancement factor of 1325. This spectral advantage plus the preconcentration factor achieved, contributed to the method sensitivity allowing the ergotamine determination at trace level concentration. Under optimal experimental conditions, a linear calibration curve was obtained from 3.81×10(-7) to 1.10μgmL(-1), with detection and quantification limits of 0.11 and 0.38pgmL(-1), respectively. The accuracy and versatility of the present methodology were proved by analyzing ergotamine in real samples of different natures such as pharmaceuticals, urine and saliva. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Sensor array and preconcentrator for the detection of explosives in water

    NASA Astrophysics Data System (ADS)

    Woodka, Marc D.; Shpil, J. Cory; Schnee, Vincent P.; Polcha, J. Michael P.

    2012-06-01

    A sensor system has been constructed that is capable of detecting and discriminating between various explosives presented in ocean water with detection limits at the 10-100 parts per trillion level. The sensor discriminates between different compounds using a biologically-inspired fluorescent polymer sensor array, which responds with a unique fluorescence quenching pattern during exposure to different analytes. The sensor array was made from commercially available fluorescent polymers coated onto glass beads, and was demonstrated to discriminate between different electron-withdrawing analytes delivered in salt water solutions, including the explosives 2,4,6-trinitrotoluene (TNT) and tetryl, the explosive hydrolysis products 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene, as well as other explosive-related compounds and explosive simulants. Sensitivities of 10-100 parts per trillion were achieved by employing a preconcentrator (PC) upstream of the sensor inlet. The PC consists of the porous polymer Tenax, which captures explosives from contaminated water as it passes through the PC. As the concentration of explosives in water decreased, longer loading times were required to concentrate a detectable amount of explosives within the PC. Explosives accumulated within the PC were released to the sensor array by heating the PC to 190 C. This approach yielded preconcentration factors of up to 100-1000x, however this increased sensitivity towards lower concentrations of explosives was achieved at the expense of proportionally longer sampling times. Strategies for decreasing this sampling time are discussed.

  10. Reduction Smelting Low Ferronickel from Pre-concentrated Nickel-Iron Ore of Nickel Laterite

    NASA Astrophysics Data System (ADS)

    Zhu, Deqing; Zhou, Xianlin; Luo, Yanhong; Pan, Jian; Bai, Bing

    2016-11-01

    The research of smelting low ferronickel from pre-concentrate nickel-iron ore with 2.76 % Ni and 38.00 % Fetotal was carried out to find an effective way for stainless steel enterprises to use the low-nickel laterite reasonable. The results show that Ni and Fe both have a certain degree of enrichment, and impurities and harm elements have different degrees of reduction after pre-concentration of nickel-iron ore. Most valuable metal did not compound with impurities which greatly accelerated the speed and extent of melt separation reduction. Good alloy of 6.58 % Ni with the overall recoveries of 93.38 % and 89.95 % Fetotal with the overall recoveries of 89.57 % was manufactured under the following conditions: 10 % coke, 1.0 binary basicity, 18 % MgO and 3 % Al2O3 in slag, melting at 1,550 °C for 10 min. The product can be used for the feed of producing stainless steel.

  11. Development and Evaluation of Nanoemulsifying Preconcentrate of Curcumin for Colon Delivery

    PubMed Central

    Wadhwa, Jyoti; Asthana, Abhay; Shilakari, Gyati; Chopra, Arun Kumar; Singh, Ranjit

    2015-01-01

    The present study aimed to develop and optimize a nanoemulsifying preconcentrate formulation of curcumin with good emulsification ability and optimal globule size, for controlled targeting in colon. Content of formulation variables, namely, X1 (Peceol), X2 (Cremophor-EL), and X3 (Transcutol HP), were optimized by Box-Behnken design of experiments for its impact on mean globule size (Y1), emulsification time (Y2), and time required for drug release (85%) in phosphate buffer (pH 7.2), t85% (Y3). Transmission electron micrographs confirmed that there is no coalescence among globules, with size range concordant with the globule size analysis by dynamic light scattering technique (100 nm). 3D plots indicated that concentration of formulation ingredients significantly influences the formulation properties (globule size, emulsification time, and drug release). In vitro release profile (in phosphate buffer; pH 7.2) represents the fact that more than 50% of the drug was released within initial 15 min whereas in vivo release showed limited systemic absorption (Cmax 200 ng/mL) of curcumin. Stability study ensures the protection of drug in alkaline media which may further confirm the localised delivery of drug to colonic region. Study demonstrated that the nanoemulsifying preconcentrate can be a promising system for the colon specific delivery of curcumin to treat local pathologies. PMID:25861680

  12. Amplified electrochemical detection of nucleic acid hybridization via selective preconcentration of unmodified gold nanoparticles.

    PubMed

    Li, Yuan; Tian, Rui; Zheng, Xingwang; Huang, Rongfu

    2016-08-31

    The common drawback of optical methods for rapid detection of nucleic acid by exploiting the differential affinity of single-/double-stranded nucleic acids for unmodified gold nanoparticles (AuNPs) is its relatively low sensitivity. In this article, on the basis of selective preconcentration of AuNPs unprotected by single-stranded DNA (ssDNA) binding, a novel electrochemical strategy for nucleic acid sequence identification assay has been developed. Through detecting the redox signal mediated by AuNPs on 1, 6-hexanedithiol blocked gold electrode, the proposed method is able to ensure substantial signal amplification and a low background current. This strategy is demonstrated for quantitative analysis of the target microRNA (let-7a) in human breast adenocarcinoma cells, and a detection limit of 16 fM is readily achieved with desirable specificity and sensitivity. These results indicate that the selective preconcentration of AuNPs for electrochemical signal readout can offer a promising platform for the detection of specific nucleic acid sequence.

  13. Highly selective preconcentration of ultra-trace cadmium by yeast surface engineering.

    PubMed

    Yang, Ting; Zhang, Xiao-Xing; Chen, Ming-Li; Wang, Jian-Hua

    2012-09-21

    The potential of selective cell-sorption for separation/preconcentration of ultra-trace heavy metals was exploited by surface engineering of Saccharomyces cerevisiae cells. The general idea is to display the cadmium-binding peptide on the cell surface in order to enhance the covalent interaction between cadmium and the yeast cells. By immobilizing the surface-engineered yeast cells onto cytopore(®) microcarrier beads for cadmium adsorption, we demonstrated that with respect to the native yeast 600-fold and 25-1000-fold improvements were observed respectively for the tolerance of ionic strength and the tolerant capability toward various metal cations after surface engineering. Based on these observations, a novel procedure for selective cadmium preconcentration was developed with detection by graphite furnace atomic absorption spectrometry (GFAAS), employing the engineered S. cerevisiae cell-loaded cytopore(®) beads as a renewable sorption medium incorporated into a sequential injection lab-on-valve system. The cadmium retained on the yeast cell surface was eluted with a small amount of nitric acid and quantified with GFAAS. Within a range of 5-100 ng L(-1) and a sample volume of 1 mL, an enrichment factor of 30 was achieved along with a detection limit of 1.1 ng L(-1), a sampling frequency of 20 h(-1) and a precision of 3.3% RSD at 50 ng L(-1). The procedure was validated by analyzing cadmium in certified reference materials and a series of environmental water samples.

  14. Solid phase extraction for the speciation and preconcentration of inorganic selenium in water samples: a review.

    PubMed

    Herrero Latorre, C; Barciela García, J; García Martín, S; Peña Crecente, R M

    2013-12-04

    Selenium is an essential element for the normal cellular function of living organisms. However, selenium is toxic at concentrations of only three to five times higher than the essential concentration. The inorganic forms (mainly selenite and selenate) present in environmental water generally exhibit higher toxicity (up to 40 times) than organic forms. Therefore, the determination of low levels of different inorganic selenium species in water is an analytical challenge. Solid-phase extraction has been used as a separation and/or preconcentration technique prior to the determination of selenium species due to the need for accurate measurements for Se species in water at extremely low levels. The present paper provides a critical review of the published methods for inorganic selenium speciation in water samples using solid phase extraction as a preconcentration procedure. On the basis of more than 75 references, the different speciation strategies used for this task have been highlighted and classified. The solid-phase extraction sorbents and the performance and analytical characteristics of the developed methods for Se speciation are also discussed.

  15. Online sample pre-concentration via dynamic pH junction in capillary and microchip electrophoresis.

    PubMed

    Kazarian, Artaches A; Hilder, Emily F; Breadmore, Michael C

    2011-10-01

    Various analytical techniques have been developed over the years to analyse a large diversity of biomolecules with a constant push towards ultra-sensitive detection. CE is at the forefront of the most powerful analytical tools available to date when considering its superior efficiency and resolution; however, the technique suffers from poor sensitivity as a result of the short path length at the detection site and small injection volumes (typically <1% capillary length). One of the approaches to abate the inherent problem is to employ clever chemistry using sample focusing techniques whereby a large sample plug can be injected, preconcentrated and separated, producing excellent sensitivity and efficiency at the detector. This particular review will focus on the use of dynamic pH junction as a means of improving sensitivity in CE and focuses on the use of a change in analyte ionisation due to different pHs between the sample and electrolyte. The review provides a fundamental discussion of the mechanisms, buffer and sample conditions required to concentrate various analytes and a comprehensive list of published works in tabular format for easy identification of suitable conditions for new applications. The review further encompasses the use of dynamic pH junction in CE and its involvement in combination with other preconcentrations techniques to produce high sensitivity enhancements recorded between the years 1990-2010.

  16. Astronomy On-Line Programme Enters "hot Week"

    NASA Astrophysics Data System (ADS)

    1996-11-01

    World's Biggest Astronomy WWW-Event Attracts Thousands of Students The Astronomy On-line Programme (See ESO Press Release 09/96 of 18 June 1996) began officially on 1 October and is now about to enter its most intense phase, known as the Hot Week . On 18 - 22 November, an estimated 4000 astronomy-interested, mostly young people in Europe and on four other continents will get together during five days in what - not unexpected - has become the world's biggest astronomy event ever organised on the World Wide Web. This carefully structured Programme is carried out in collaboration between the European Association for Astronomy Education (EAAE), the European Southern Observatory and the European Commission, under the auspices of the Fourth European Week for Scientific and Technological Culture. The Programme has already had a most visible impact on the school education of natural sciences in various countries; for instance, the Internet-connection of schools has been advanced in some, in order to allow groups to participate. There have been numerous contacts among the groups across the borders and there are clear signs that many Astronomy On-line participants have progressed to use the impressive possibilities of the Web in an efficient and structured way. There has been a lively media interest in Astronomy On-line all over Europe and it is expected to increase during the next week. The current status of Astronomy On-line It is obvious that the pilot function of the Astronomy On-line Programme in the use of the Web has been very effective and that the associated dissemination of astronomical knowledge has been successful. At this time, more than 650 groups have registered with Astronomy On-line. Most come from 31 different European countries and a few dozen groups are located in North and South America as well as in Asia and Australia. Together they have experienced the steady build-up of Astronomy On-line over the past weeks, by means of numerous contributions from a

  17. On-line sequential injection dispersive liquid-liquid microextraction system for flame atomic absorption spectrometric determination of copper and lead in water samples.

    PubMed

    Anthemidis, Aristidis N; Ioannou, Kallirroy-Ioanna G

    2009-06-30

    A simple, sensitive and powerful on-line sequential injection (SI) dispersive liquid-liquid microextraction (DLLME) system was developed as an alternative approach for on-line metal preconcentration and separation, using extraction solvent at microlitre volume. The potentials of this novel schema, coupled to flame atomic absorption spectrometry (FAAS), were demonstrated for trace copper and lead determination in water samples. The stream of methanol (disperser solvent) containing 2.0% (v/v) xylene (extraction solvent) and 0.3% (m/v) ammonium diethyldithiophosphate (chelating agent) was merged on-line with the stream of sample (aqueous phase), resulting a cloudy mixture, which was consisted of fine droplets of the extraction solvent dispersed entirely into the aqueous phase. By this continuous process, metal chelating complexes were formed and extracted into the fine droplets of the extraction solvent. The hydrophobic droplets of organic phase were retained into a microcolumn packed with PTFE-turnings. A portion of 300 microL isobutylmethylketone was used for quantitative elution of the analytes, which transported directly to the nebulizer of FAAS. All the critical parameters of the system such as type of extraction solvent, flow-rate of disperser and sample, extraction time as well as the chemical parameters were studied. Under the optimum conditions the enhancement factor for copper and lead was 560 and 265, respectively. For copper, the detection limit and the precision (R.S.D.) were 0.04 microg L(-1) and 2.1% at 2.0 microg L(-1) Cu(II), respectively, while for lead were 0.54 microg L(-1) and 1.9% at 30.0 microg L(-1) Pb(II), respectively. The developed method was evaluated by analyzing certified reference material and applied successfully to the analysis of environmental water samples.

  18. Volatile organic compounds emitted after leaf wounding: On-line analysis by proton-transfer-reaction mass spectrometry

    NASA Astrophysics Data System (ADS)

    Fall, Ray; Karl, Thomas; Hansel, Armin; Jordan, Alfons; Lindinger, Werner

    1999-07-01

    Volatile organic compounds (VOCs) released from vegetation, including wound-induced VOCs, can have important effects on atmospheric chemistry. The analytical methods for measuring wound-induced VOCs, especially the hexenal family of VOCs (hexenals, hexenols, and hexenyl esters), are complicated by their chemical instability and the transient nature of their formation after leaf and stem wounding. Here we demonstrate that formation and emission of hexenal family compounds can be monitored on-line using proton-transfer-reaction mass spectrometry (PTR-MS), avoiding the need for preconcentration or chromatography. These measurements allow direct analysis of the rapid emission of the parent compound, (Z)-3-hexenal, within 1-2 s of wounding of aspen leaves and then its disappearance and the appearance of its metabolites including (E)-2-hexenal, hexenols, and hexenyl acetates. Similar results were seen in wounded beech leaves and clover. The emission of hexenal family compounds was proportional to the extent of wounding, was not dependent on light, occurred in attached or detached leaves, and was greatly enhanced as detached leaves dried out. Emission of (Z)-3-hexenal from detached drying aspen leaves averaged 500 μg C g-1 (dry leaf weight). Leaf wound compounds were not emitted in a nitrogen atmosphere but were released within seconds of reintroduction of oxygen; this indicates that there are not large pools of hexenyl compounds in leaves. The PTR-MS method also allows the simultaneous detection of less abundant hexanal family VOCs including hexanal, hexanol, and hexyl acetate and VOCs formed in the light (isoprene) or during anoxia (acetaldehyde). PTR-MS may be a useful tool for the analysis of VOC emissions resulting from grazing, herbivory, and other physical damage to vegetation, from harvesting of crops, and from senescing leaves.

  19. Molecularly imprinted on-line solid-phase extraction combined with flow-injection chemiluminescence for the determination of tetracycline.

    PubMed

    Xiong, Yan; Zhou, Houjiang; Zhang, Zhujun; He, Deyong; He, Chao

    2006-07-01

    A molecularly imprinted polymer solid phase extraction (MISPE) method combined with flow-injection chemiluminescence (FI-CL) for the determination of residual tetracycline (TC) in fish samples is presented. The molecularly imprinted polymer (MIP) of TC was synthesized and particles of this MIP were packed into a polytetrafluoroethylene (PTFE) tube, which was connected into the sampling loop of an eight-way injection valve and served as the MISPE column for on-line selective adsorption of TC. The eluent (CH3CN : HNO3 (0.01 mol L(-1)) = 4 ratio 1, v ratio v) was used for extracting the adsorbed TC, which could be detected by its good enhancing effect on the CL reaction between Ce(iv) and rhodamine B. The CL intensity is linear to TC concentration in the range from 4 x 10(-9) to 4 x 10(-7) g mL(-1). The detection limit is 1 x 10(-9) g mL(-1) (3 sigma) and the relative standard deviation is 2.4% (n = 9). The conditions of preconcentration, extraction and CL reaction were carefully studied. The selectivity experiment shows that the selectivity and sensitivity of the CL method could be improved greatly when MIP was used as a recognition material in SPE. However, the MISPE column interacted indiscriminately with oxytetracycline (OTC) with a 49 +/- 2% binding. An intermediate differential pulsed elution (DPE) step using 3% acetic acid as eluent was employed to remove OTC and other interfering substances. The proposed MISPE-CL method has been applied successfully to the determination of TC in fish samples. At the same time, the binding characteristics of the polymer to tetracycline were evaluated by batch and dynamic methods.

  20. Salting-out solvent extraction for the off-line preconcentration of benzalkonium chloride in capillary electrophoresis.

    PubMed

    So, T S; Huie, C W

    2001-07-01

    The use of salting-out effect for the off-line preconcentration of charged analytes in capillary electrophoresis is demonstrated for the first time. Using benzalkonium chloride (BAK) as model compound, a mixture of cationic surfactants consisting of even-numbered alkylbenzyl quaternary ammonium homologues (C8-C18), the addition of appropriate amounts of sodium chloride and acetonitrile in the sample solution (2 mL sample volume) was found to be capable of providing ca. 40-fold enhancement in detection sensitivity. In addition to affording a preconcentrating effect due to the extraction of BAK in the smaller volume water-miscible organic solvent phase (acetonitrile), the organic solvent also serves to improve the peak area and shape of the longer chain surfactants. Optimal experimental conditions, such as volume of acetonitrile and concentration of sodium chloride, for the preconcentration of BAK with good preconcentration factors and reproducibility were investigated. The usefulness of the present method was demonstrated for the improved determination of BAK present in commercially available industrial and pharmaceutical products.

  1. Preconcentration and Separation of Mixed-Species Samples Near a Nano-Junction in a Convergent Microchannel.

    PubMed

    Chiu, Ping-Hsien; Weng, Chen-Hsun; Yang, Ruey-Jen

    2015-12-05

    A fluidic microchip incorporating a convergent microchannel and a Nafion-nanoporous membrane is proposed for the preconcentration and separation of multi-species samples on a single platform. In the device, sample preconcentration is achieved by means of the ion concentration polarization effect induced at the micro/nano interface under the application of an external electric field, while species separation is achieved by exploiting the different electrophoretic mobilities of the sample components. The experimental results show that the device is capable of detecting C-reactive protein (CRP) with an initial concentration as low as 9.50 × 10(-6) mg/L given a sufficient preconcentration time and driving voltage. In addition, it is shown that a mixed-species sample consisting of three negatively-charged components (bovine serum albumin (BSA), tetramethylrhodamine(TAMRA) isothiocyanate-Dextran and fluorescent polymer beads) can be separated and preconcentrated within 20 min given a driving voltage of 100 V across 1 cm microchannel in length. In general, the present results confirm the feasibility of the device for the immunoassay or detection of various multi-species samples under low concentration in the biochemical and biomedical fields. The novel device can therefore improve the detection limit of traditional medical facilities.

  2. Micro-total analysis system for virus detection: microfluidic pre-concentration coupled to liposome-based detection.

    PubMed

    Connelly, John T; Kondapalli, Sowmya; Skoupi, Marc; Parker, John S L; Kirby, Brian J; Baeumner, Antje J

    2012-01-01

    An integrated microfluidic biosensor is presented that combines sample pre-concentration and liposome-based signal amplification for the detection of enteric viruses present in environmental water samples. This microfluidic approach overcomes the challenges of long assay times of cell culture-based methods and the need to extensively process water samples to eliminate inhibitors for PCR-based methods. Here, viruses are detected using an immunoassay sandwich approach with the reporting antibodies tagged to liposomes. Described is the development of the integrated device for the detection of environmentally relevant viruses using feline calicivirus (FCV) as a model organism for human norovirus. In situ fabricated nanoporous membranes in glass microchannels were used in conjunction with electric fields to achieve pre-concentration of virus-liposome complexes and therefore enhance the antibody-virus binding efficiency. The concentrated complexes were eluted to a detection region downstream where captured liposomes were lysed to release fluorescent dye molecules that were then quantified using image processing. This system was compared to an optimized electrochemical liposome-based microfluidic biosensor without pre-concentration. The limit of detection of FCV of the integrated device was at 1.6 × 10(5) PFU/mL, an order of magnitude lower than that obtained using the microfluidic biosensor without pre-concentration. This significant improvement is a key step toward the goal of using this integrated device as an early screening system for viruses in environmental water samples.

  3. Determination of five priority haloacetic acids by capillary electrophoresis with contactless conductivity detection and solid phase extraction preconcentration.

    PubMed

    Kubáň, Petr; Makarõtševa, Natalja; Kiplagat, Isaac K; Kaljurand, Mihkel

    2012-03-01

    A sensitive capillary electrophoretic separation method with contactless conductivity detection (C4D) for analysis of five priority haloacetic acids (HAA5) is presented. The analytes were baseline separated in an electrolyte composed of 20 mM 2-(N-Morpholino) ethanesulfonic acid (MES), 20 mM L-histidine (HIS), and 30 μM cetyltrimethylammonium bromide (CTAB) at pH 6.0 in less than 4 min. A simplified solid-phase extraction (SPE) preconcentration procedure on highly cross-linked polystyrene-divinylbenzene (PS-DVB) type sorbent was developed and optimized with respect to short preconcentration time. HAA5 from a 25-mL sample aliquot of tap and swimming pool water could be preconcentrated in less than 5 min using an in-house made SPE column with recoveries ranging from 23 to 98%. Combining the SPE preconcentration procedure with capillary electrophoretic analysis, the attained limits of detection were between 6.1 and 12.2 μg/L with total analysis time of less than 10 min.

  4. PHENIX on-line and off-line computing

    NASA Astrophysics Data System (ADS)

    Adler, S. S.; Chujo, T.; Desmond, E. J.; Ewell, L.; Ghosh, T. K.; Haggerty, J. S.; Ichihara, T.; Jacak, B. V.; Johnson, S. C.; Kehayias, H.-J.; Lauret, J.; Maguire, C. F.; Messer, M.; Mioduszewski, S.; Mitchell, J. T.; Morrison, D. P.; Ojha, I. D.; Pinkenburg, C. H.; Pollack, M.; Pope, K.; Purschke, M. L.; Sorensen, S.; Sourikova, I.; Thomas, T. L.; Velkovsky, M.; Watanabe, Y.; Witzig, C.; Yokkaichi, S.; Zajc, W. A.; PHEN. I. X. Collaboration

    2003-03-01

    Data handling in PHENIX is carried out by the On-Line Computing System (ONCS) and Off-Line Computing System (Off-Line). ONCS provides the overall control and monitoring of the front-end electronics, trigger and data acquisition system and detector ancillary systems. It configures and initializes the on-line system, monitors and controls the data flow, coordinates calibration processes, interlocks the data acquisition process with the slow control subsystems and performs a number of other functions. ONCS uses CORBA software to monitor and control the hardware. Off-Line provides all aspects of data handling not directly connected to the collection of data and monitoring, such as event simulation and reconstruction, data analysis and information management. The impact of the unprecedented data volumes on the design is presented, along with a detailed discussion of the tasks and methods of simulating, obtaining and monitoring the data.

  5. On-line object feature extraction for multispectral scene representation

    NASA Technical Reports Server (NTRS)

    Ghassemian, Hassan; Landgrebe, David

    1988-01-01

    A new on-line unsupervised object-feature extraction method is presented that reduces the complexity and costs associated with the analysis of the multispectral image data and data transmission, storage, archival and distribution. The ambiguity in the object detection process can be reduced if the spatial dependencies, which exist among the adjacent pixels, are intelligently incorporated into the decision making process. The unity relation was defined that must exist among the pixels of an object. Automatic Multispectral Image Compaction Algorithm (AMICA) uses the within object pixel-feature gradient vector as a valuable contextual information to construct the object's features, which preserve the class separability information within the data. For on-line object extraction the path-hypothesis and the basic mathematical tools for its realization are introduced in terms of a specific similarity measure and adjacency relation. AMICA is applied to several sets of real image data, and the performance and reliability of features is evaluated.

  6. On-line range prediction system, part 2

    NASA Technical Reports Server (NTRS)

    Levan, Nhan

    1988-01-01

    The on-line range prediction system is designed for providing a prediction of the target range in the case of a laser data dropout. It consists of real time implementation of a Kalman filter on an IBM PC/AT equipped with necessary hardware. The system was set up and tested at Crows Landing in the Fall of 1987. The improvements made on the on-line range prediction system during 1988 are examined. Solutions are proposed and discussed to the several problems encountered during system tests. Then, the improvements made on the filter software are explained, namely, accounting for the time lag and providing data continously. Finally, the ideas are mentioned that can be considered in the future.

  7. On-line analyzers to distributed control system linking

    SciTech Connect

    Peterson, S.F.; Buchanan, B.R.; Sanders, M.A.

    1990-01-01

    The Analytical Development Section (ADS) of the Savannah River Laboratory is developing on-line analyzers to monitor various site processes. Data from some of the on-line analyzers (OLA's) will be used for process control by distributed control systems (DCS's) such as the Fisher PRoVOX. A problem in the past has been an efficient and cost effective way to get analyzer data onto the DCS data highway. ADS is developing a system to accomplish the linking of OLA's to PRoVOX DCS's. The system will be described, and results of operation in a research and development environment given. Plans for the installation in the production environment will be discussed.

  8. The CEBAF on-line data acquisition system

    SciTech Connect

    Heyes, G.; Watson, W.A. III; Jastrzembski, E.; Chen, J.; Abbott, D.; Barker, D.

    1994-12-31

    The CEBAF On-line Data Acquisition system, CODA, is a flexible modular data acquisition system which has been designed to provide a common platform for data acquisition for the three experimental halls at CEBAF. CODA has been in use in detector tests at CEBAF and on-line in experiments at other laboratories (LSND, CHAOS). CODA runs on a distributed network of machines running the UNIX and VxWorks operating systems. The VxWorks systems may be embedded processors in VME, CAMAC or FASTBUS. The UNIX systems currently supported are ULTRIX and HP-UX. The system is modular and scalable and is designed to be easily ported to any future operating systems. This paper describes the main features of the current release of CODA and enhancements to CODA currently under development in preparation for the commissioning of the CEBAF detectors.

  9. Digital video system for on-line portal verification

    NASA Astrophysics Data System (ADS)

    Leszczynski, Konrad W.; Shalev, Shlomo; Cosby, N. Scott

    1990-07-01

    A digital system has been developed for on-line acquisition, processing and display of portal images during radiation therapy treatment. A metal/phosphor screen combination is the primary detector, where the conversion from high-energy photons to visible light takes place. A mirror angled at 45 degrees reflects the primary image to a low-light-level camera, which is removed from the direct radiation beam. The image registered by the camera is digitized, processed and displayed on a CRT monitor. Advanced digital techniques for processing of on-line images have been developed and implemented to enhance image contrast and suppress the noise. Some elements of automated radiotherapy treatment verification have been introduced.

  10. Training end-users: An on-line help package

    SciTech Connect

    Waite, M.

    1992-03-01

    No matter how wonderful your INGRES application, if the end users don`t know how to use the application it will not be utilized. This paper discusses an on-line help package implemented in our manufacturing database application in order to help our user community use the application. The Materials Fabrication Division (MFD) of Mechanical Engineering is a series of machining shops that do production jobs for the Laboratory. The Fabrication Control System (FCS) is the user interface to an INGRES database. FCS tracks jobs as they traverse the machine shops and FCS maintains the employee payroll. This interface consists of VIFRED forms, menus and EQUEL Fortran code. The on-line help package is an interactive system that responds to the users ``single key stroke`` request for information. The information retrieved is based upon which help key is used and the form or menu from which the request is generated.

  11. On-Line Metrology with Conoscopic Holography: Beyond Triangulation

    PubMed Central

    Álvarez, Ignacio; Enguita, Jose M.; Frade, María; Marina, Jorge; Ojea, Guillermo

    2009-01-01

    On-line non-contact surface inspection with high precision is still an open problem. Laser triangulation techniques are the most common solution for this kind of systems, but there exist fundamental limitations to their applicability when high precisions, long standoffs or large apertures are needed, and when there are difficult operating conditions. Other methods are, in general, not applicable in hostile environments or inadequate for on-line measurement. In this paper we review the latest research in Conoscopic Holography, an interferometric technique that has been applied successfully in this kind of applications, ranging from submicrometric roughness measurements, to long standoff sensors for surface defect detection in steel at high temperatures. PMID:22399984

  12. On-line application of the PANTHER advanced nodal code

    SciTech Connect

    Hutt, P.K.; Knight, M.P. )

    1992-01-01

    Over the last few years, Nuclear Electric has developed an integrated core performance code package for both light water reactors (LWRs) and advanced gas-cooled reactors (AGRs) that can perform a comprehensive range of calculations for fuel cycle design, safety analysis, and on-line operational support for such plants. The package consists of the following codes: WIMS for lattice physics, PANTHER whole reactor nodal flux and AGR thermal hydraulics, VIPRE for LWR thermal hydraulics, and ENIGMA for fuel performance. These codes are integrated within a UNIX-based interactive system called the Reactor Physics Workbench (RPW), which provides an interactive graphic user interface and quality assurance records/data management. The RPW can also control calculational sequences and data flows. The package has been designed to run both off-line and on-line accessing plant data through the RPW.

  13. On-Line Patient Information System with Query

    PubMed Central

    Hayeck, Elie G.; Berman, William J.; Anné, Antharvedi

    1979-01-01

    Background, current state and future plans for the University of Virginia Biomedical Engineering Division Patient Information System are given. System design is highlighted. When fully implemented, the system will make extensive use of “block transmission,” made for user-computer interaction, for data input, retrieval, and update. Other features will include the possibility of multiple primary keys per patient, frequency distribution, on-line patient query (i.e., search on secondary keys), and general printouts.

  14. An on-line expert system to improve heat rate

    SciTech Connect

    Shirley, R.S.; Forbes, H.; Nelson, R.F.

    1992-01-01

    A closed-loop expert system for supervisory control is described. The expert system, called ThermoPlus, is designed to help improve heat rates in a power plant, and is tested on a research, solar/fossil pilot plant. This paper describes the management of the project, including problem selection, controlling problem size, and designing the knowledge base. Initial results form running the expert system on line (but not closed-loop) are included.

  15. On-line fluorescent techniques for diagnostics of water environment

    NASA Astrophysics Data System (ADS)

    Babichenko, Sergey M.; Lapimaa, Juri; Porovkina, Larissa; Varlamov, Victor

    1995-09-01

    An approach of on-line fluorescent analysis of organic compounds in a water is described based on multiwavelength sensing of water environment. Developed techniques are realized in remote mode to inspect large water surfaces as well as in flow-trough mode to diagnose the water quality in the pipes and open streams. The tuneable fluorescent lidars FLS-S and FLS-A for shipboard and airborne applications and compact flow-through spectrofluorimeter FLUO- IMAGER are described.

  16. On-line determination of optimal flight paths for helicopters

    NASA Technical Reports Server (NTRS)

    Slater, G. L.; Stoughton, M.

    1984-01-01

    A procedure for computing fuel optimal fixed range trajectories is developed for helicopters. The algorithm uses a simplified dynamic model and a climb-cruise-descent assumption which simplifies the variational problem to an algebraic minimization. Development of the performance model is discussed extensively and representative results for the S-61 and S-76 helicopters are presented. The results show that the model and optimization algorithm are small enough and simple enough to be incorporated into an on-line optimization algorithm.

  17. Vibration-insensitive interferometer for on-line measurements.

    PubMed

    Melozzi, M; Pezzati, L; Mazzoni, A

    1995-09-01

    We have realized a digital Twyman-Green interferometer to measure the quality of optical surfaces in unstable environments. The system yields accurate measurements even in the presence of severe mechanical vibrations. The interferograms are decoded by application of a spatial-carrier phase-shifting fringe-analysis technique. The interferometer was mounted over a production machine and used for on-line measurements of aspheric mirror surfaces during the figuring and polishing process.

  18. DEVELOPMENT OF AN ON-LINE COAL WASHABILITY ANALYZER

    SciTech Connect

    C.L. Lin; G.H. Luttrell; G.T. Adel; Jan D. Miller

    1999-03-31

    Washability analysis is the basis for nearly all coal preparation plant separations. Unfortunately, there are no on-line techniques for determining this most fundamental of all coal cleaning information. In light of recent successes at the University of Utah, it now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. The successful development of such a device is critical to the establishment of process control and automated coal blending systems. In this regard, Virginia Tech, Terra Tek Inc., and several eastern coal companies have joined with the University of Utah and agreed to undertake the development of a x-ray CT-based on-line coal washability analyzer with financial assistance from DOE. The three-year project will cost $594,571, of which 33% ($194,575) will be cost-shared by the participants. The project involves development of appropriate software and extensive testing/evaluation of well-characterized coal samples from operating coal preparation plants. Each project participant brings special expertise to the project which is expected to create a new dimension in coal cleaning technology. Finally, it should be noted that the analyzer may prove to be a universal analyzer capable of providing not only washability analysis, but also particle size distribution analysis, ash analysis and perhaps pyritic sulfur analysis.

  19. Electrochemistry combined on-line with electrospray mass spectrometry

    SciTech Connect

    Zhou, F.; Berkel, G.J.V.

    1995-10-15

    In this paper a variety of methods to couple electrochemistry on-line with electrospray mass spectrometry (EC/ES-MS) are presented, and the fundamental and analytical utility of this hybrid technique is illustrated. The major problems encountered in coupling EC and ES-MS are discussed, and means to overcome them are presented. Three types of electrochemical flow cells, viz., a thin-layer electrode flow-by cell, a tubular electrode flow-through cell, and a porous electrode flow-through cell, are discussed in regard to their suitability for this coupling. Methods for coupling each of these electrochemical cells on-line with ES-MS, either floated at or decoupled from the ES high voltage and controlled by a constant current supply, a constant potential supply, or a potentiostat are presented. Three applications are used to illustrate the utility and versatility of the EC/ES-MS combination: (1) the ionization of neutral analytes (i.e., perylene) for detection by ES-MS, (2) the study of the products of electrode reactions (i.e., nickel(II) octaethylporphyrin oxidation products), including relatively short-lived products (i.e., {Beta}-carotene oxidation products), and (3) the enhanced determination of metals (i.e., elemental silver) achieved by coupling anodic stripping voltammetry on-line with ES-MS. 52 refs., 6 figs.

  20. Designing effective on-line continuing medical education.

    PubMed

    Zimitat, Craig

    2001-03-01

    The Internet, and new information and communication technologies available through the Internet, provides medical educators with an opportunity to develop unique on-line learning environments with real potential to improve physicians' knowledge and effect change in their clinical practice. There are approximately 100 websites offering on-line CME courses in the USA alone. However, few of these CME courses appear to be based on sound educational principles or CME research and may have little chance of achieving the broader goals of CME. The majority of these courses closely resemble their traditional counterparts (e.g. paper-based books are now electronic books) and appear to be mere substitutions for old-technology CME resources. Whilst some CME providers add unique features of the Internet to enrich their websites, they do not employ strategies to optimize the learning opportunities afforded by this new technology. The adoption of adult learning principles, reflective practice and problem-based approaches can be used as a foundation for sound CME course design. In addition, knowledge of Internet technology and the learning opportunities it affords, together with strategies to maintain participation and new assessment paradigms, are all needed for developing online CME. We argue for an evidence-based and strategic approach to the development of on-line CME courses designed to enhance physician learning and facilitate change in clinical behaviour.

  1. Problem formulation, metrics, open government, and on-line collaboration

    NASA Astrophysics Data System (ADS)

    Ziegler, C. R.; Schofield, K.; Young, S.; Shaw, D.

    2010-12-01

    Problem formulation leading to effective environmental management, including synthesis and application of science by government agencies, may benefit from collaborative on-line environments. This is illustrated by two interconnected projects: 1) literature-based evidence tools that support causal assessment and problem formulation, and 2) development of output, outcome, and sustainability metrics for tracking environmental conditions. Specifically, peer-production mechanisms allow for global contribution to science-based causal evidence databases, and subsequent crowd-sourced development of causal networks supported by that evidence. In turn, science-based causal networks may inform problem formulation and selection of metrics or indicators to track environmental condition (or problem status). Selecting and developing metrics in a collaborative on-line environment may improve stakeholder buy-in, the explicit relevance of metrics to planning, and the ability to approach problem apportionment or accountability, and to define success or sustainability. Challenges include contribution governance, data-sharing incentives, linking on-line interfaces to data service providers, and the intersection of environmental science and social science. Degree of framework access and confidentiality may vary by group and/or individual, but may ultimately be geared at demonstrating connections between science and decision making and supporting a culture of open government, by fostering transparency, public engagement, and collaboration.

  2. Review of trigger and on-line processors at SLAC

    SciTech Connect

    Lankford, A.J.

    1984-07-01

    The role of trigger and on-line processors in reducing data rates to manageable proportions in e/sup +/e/sup -/ physics experiments is defined not by high physics or background rates, but by the large event sizes of the general-purpose detectors employed. The rate of e/sup +/e/sup -/ annihilation is low, and backgrounds are not high; yet the number of physics processes which can be studied is vast and varied. This paper begins by briefly describing the role of trigger processors in the e/sup +/e/sup -/ context. The usual flow of the trigger decision process is illustrated with selected examples of SLAC trigger processing. The features are mentioned of triggering at the SLC and the trigger processing plans of the two SLC detectors: The Mark II and the SLD. The most common on-line processors at SLAC, the BADC, the SLAC Scanner Processor, the SLAC FASTBUS Controller, and the VAX CAMAC Channel, are discussed. Uses of the 168/E, 3081/E, and FASTBUS VAX processors are mentioned. The manner in which these processors are interfaced and the function they serve on line is described. Finally, the accelerator control system for the SLC is outlined. This paper is a survey in nature, and hence, relies heavily upon references to previous publications for detailed description of work mentioned here. 27 references, 9 figures, 1 table.

  3. Multi-parameter on-line coal bulk analysis

    SciTech Connect

    1999-02-01

    This was a four-year grant that was given a no cost extension for one more year. The purpose of the grant was to develop a pulsed neutron-based technique that could measure on-line all the major and minor elements in coal. Such measurements would allow the continuous monitoring of bulk parameters such as coal heating value (BTU/lb), volatile matter, moisture etc., deemed important to the coal industry. Such parameters, along with the continuous measurement of elements such as sulfur and sodium, are of major economic and environmental concern, and their measurement would assist in a more efficient use of the coal-fired boilers, as well as limiting emissions controlled by the 1990 Clean Air Act Amendments. It was hoped that this study would lead to the development of a technique able to create a marketable product, an On-Line Elemental Coal Analyzer. The study was separated in the following major parts: (1) Devise an efficient system for the detection of gamma rays; (2) Prior to experimentation, perform modeling and simulations for items such as detector shielding, coal sample configuration, and neutron tube collimation; (3) Develop a computer code for data reduction and analysis; (4) Measure the elemental composition of various coal samples; and (5) Design a prototype, on-line elemental coal analyzer, based on the PFTNA principle.

  4. On-line breath analysis with PTR-TOF.

    PubMed

    Herbig, Jens; Müller, Markus; Schallhart, Simon; Titzmann, Thorsten; Graus, Martin; Hansel, Armin

    2009-06-01

    We report on on-line breath gas analysis with a new type of analytical instrument, which represents the next generation of proton-transfer-reaction mass spectrometers. This time-of-flight mass spectrometer in combination with the soft proton-transfer-reaction ionization (PTR-TOF) offers numerous advantages for the sensitive detection of volatile organic compounds and overcomes several limitations. First, a time-of-flight instrument allows for a measurement of a complete mass spectrum within a fraction of a second. Second, a high mass resolving power enables the separation of isobaric molecules and the identification of their chemical composition. We present the first on-line breath measurements with a PTR-TOF and demonstrate the advantages for on-line breath analysis. In combination with buffered end-tidal (BET) sampling, we obtain a complete mass spectrum up to 320 Th within one exhalation with a signal-to-noise ratio sufficient to measure down to pptv levels. We exploit the high mass resolving power to identify the main components in the breath composition of several healthy volunteers.

  5. The new on-line Czech Food Composition Database.

    PubMed

    Machackova, Marie; Holasova, Marie; Maskova, Eva

    2013-10-01

    The new on-line Czech Food Composition Database (FCDB) was launched on http://www.czfcdb.cz in December 2010 as a main freely available channel for dissemination of Czech food composition data. The application is based on a complied FCDB documented according to the EuroFIR standardised procedure for full value documentation and indexing of foods by the LanguaL™ Thesaurus. A content management system was implemented for administration of the website and performing data export (comma-separated values or EuroFIR XML transport package formats) by a compiler. Reference/s are provided for each published value with linking to available freely accessible on-line sources of data (e.g. full texts, EuroFIR Document Repository, on-line national FCDBs). LanguaL™ codes are displayed within each food record as searchable keywords of the database. A photo (or a photo gallery) is used as a visual descriptor of a food item. The application is searchable on foods, components, food groups, alphabet and a multi-field advanced search. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. On-line Access to IPAC Datasets and Services

    NASA Astrophysics Data System (ADS)

    Ebert, R.

    In the past, IPAC has developed its tools and maintained its data archives to be maximally useful to visiting scientists working with IRAS data. With the IRAS data now approaching the 10 year anniversary, IPAC is making the transition to an on-line archive in order to support not only the continuing demand for access to IRAS catalogs and images, but in preparation for providing support for future infrared missions. IPAC's goal is to make all of its key data and services accessible via the Internet. Xcatscan is an on-line service providing access to the IPAC catalogs. IRSKY is a tool for planning observations in the infrared, as well as for browsing the on-line IRAS data products. It is being developed to support the astronomy community in preparing proposals for the European Infrared Space Observatory early next year. These two new services became available on the network last June. We will discuss the design strategy and implementation of these and other systems planned for the future.

  7. DEVELOPMENT OF AN ON-LINE COAL WASHABILITY ANALYZER

    SciTech Connect

    C.L. LIN; G.H. LUTTRELL; G.T. ADEL; JAN D. MILLER

    1998-03-31

    Washability analysis is the basis for nearly all coal preparation plant separations. Unfortunately, there are no on-line techniques for determining this most fundamental of all coal cleaning information. In light of recent successes at the University of Utah, it now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. The successful development of such a device is critical to the establishment of process control and automated coal blending systems. In this regard, Virginia Tech, Terra Tek Inc., and several eastern coal companies have joined with the University of Utah and agreed to undertake the development of a x-ray CT-based on-line coal washability analyzer with financial assistance from DOE. The three-year project will cost $594,571, of which 33% ($194,575) will be cost-shared by the participants. The project involves development of appropriate software and extensive testing/evaluation of well-characterized coal samples from operating coal preparation plants. Each project participant brings special expertise to the project which is expected to create a new dimension in coal cleaning technology. Finally, it should be noted that the analyzer may prove to be a universal analyzer capable of providing not only washability analysis, but also particle size distribution analysis, ash analysis and perhaps pyritic sulfur analysis.

  8. The on-line promotion and sale of nutrigenomic services.

    PubMed

    Sterling, Rene

    2008-11-01

    Nutrigenomic researchers hope to improve health through personalized nutrition, but many consider the sale of nutrigenomic services to be premature. Few studies have evaluated the promotion and sales practices of organizations hosting nutrigenomic websites. Systematic search and analysis of websites promoting nutrigenomic services in October 2006. Of the 64 organizations hosting websites, 29 organizations offered (24 of 29) or promoted (5 of 29) at-home testing and 26 organizations sold services on-line (17 of 26) or provided a direct link to on-line sales (9 of 26). A lack of transparency made it difficult to identify unique tests; however, three organizations were linked to 56% of all test mentions. Most organizations were healthcare/wellness service providers (50%) or laboratories/biotech companies (27%). Few organizations provided on-line information about laboratory certifications (20%), nutrigenomic test or research limitations (13%), test validity or utility (11%), or genetic counseling (9%). Affiliation opportunities were offered by 15 organizations. Organizations did not provide adequate information about nutrigenomic services and at-home genetic testing. Affiliation opportunities and distribution agreements suggest the promotion and sale of nutrigenomic services will continue, increasing the importance of consumer and provider education. In absence of federal regulation, organizations promoting nutrigenomic services should equate websites to product labels and include information to facilitate informed decision-making.

  9. DEVELOPMENT OF AN ON-LINE COAL WASHABILITY ANALYZER

    SciTech Connect

    J.D. Miller; C.L. Lin; G.H. Luttrell; G.T. Adel; Barbara Marin

    2001-06-26

    Washability analysis is the basis for nearly all coal preparation plant separations. Unfortunately, there are no on- line techniques for determining this most fundamental of all coal cleaning information. In light of recent successes at the University of Utah, it now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. The successful development of such a device is critical to the establishment of process control and automated coal blending systems. In this regard, Virginia Tech, Terra Tek Inc., and U.S. coal producers have joined with the University of Utah and to undertake the development of an X-ray CT-based on- line coal washability analyzer with financial assistance from DOE. Each project participant brought special expertise to the project in order to create a new dimension in coal cleaning technology. The project involves development of appropriate software and extensive testing/evaluation of well-characterized coal samples from operating coal preparation plants. Data collected to date suggest that this new technology is capable of serving as a universal analyzer that can not only provide washability analysis, but also particle size distribution analysis, ash analysis, and perhaps pyritic sulfur analysis.

  10. Implementation, Analysis, and Assessment of On-Line Teaching Evaluations

    NASA Astrophysics Data System (ADS)

    Artz, Jerry; Rundquist, Andrew

    2006-04-01

    This ongoing project involves the introduction of the new, on-line teaching evaluation that enables students to anonymously assess their teachers and courses via computer. Over the past three years of this program, student compliance has been voluntary and has varied from a high of 73%, during the pilot program, to a low of 46% during the spring of 2005. Possible reasons for the lower compliance and measures that were taken in order to increase the compliance will be discussed. Such measures may have helped increase the compliance to 64% during the fall of 2005. The evaluation instrument, student compliance, analysis of data, and assessment will be discussed. Comparisons continue to be made (1) by grade received, (2) by class standing, (3) by ethnicity, (4) by gender and (5) of science versus non-science courses. In addition to common questions answered by all students, the on-line form allows instructors to add course-specific questions. Additional disciplinary-breadth assessment questions were added for the fall 2004 evaluation. Ongoing problems that have resulted from the introduction of on-line teaching evaluations will be discussed along with successes.

  11. On-line identification of fermentation processes for ethanol production.

    PubMed

    Câmara, M M; Soares, R M; Feital, T; Naomi, P; Oki, S; Thevelein, J M; Amaral, M; Pinto, J C

    2017-07-01

    A strategy for monitoring fermentation processes, specifically, simultaneous saccharification and fermentation (SSF) of corn mash, was developed. The strategy covered the development and use of first principles, semimechanistic and unstructured process model based on major kinetic phenomena, along with mass and energy balances. The model was then used as a reference model within an identification procedure capable of running on-line. The on-line identification procedure consists on updating the reference model through the estimation of corrective parameters for certain reaction rates using the most recent process measurements. The strategy makes use of standard laboratory measurements for sugars quantification and in situ temperature and liquid level data. The model, along with the on-line identification procedure, has been tested against real industrial data and have been able to accurately predict the main variables of operational interest, i.e., state variables and its dynamics, and key process indicators. The results demonstrate that the strategy is capable of monitoring, in real time, this complex industrial biomass fermentation. This new tool provides a great support for decision-making and opens a new range of opportunities for industrial optimization.

  12. Simultaneous flow injection preconcentration of lead and cadmium using cloud point extraction and determination by atomic absorption spectrometry.

    PubMed

    Silva, Edson Luiz; Roldan, Paulo Dos Santos

    2009-01-15

    A flow injection (FI) micelle-mediated separation/preconcentration procedure for the determination of lead and cadmium by flame atomic absorption spectrometry (FAAS) has been proposed. The analytes reacted with 1-(2-thiazolylazo)-2-naphthol (TAN) to form hydrophobic chelates, which were extracted into the micelles of 0.05% (w/v) Triton X-114 in a solution buffered at pH 8.4. In the preconcentration stage, the micellar solution was continuously injected into a flow system with four mini-columns packed with cotton, glass wool, or TNT compresses for phase separation. The analytes-containing micelles were eluted from the mini-columns by a stream of 3molL(-1) HCl solution and the analytes were determined by FAAS. Chemical and flow variables affecting the preconcentration of the analytes were studied. For 15mL of preconcentrated solution, the enhancement factors varied between 15.1 and 20.3, the limits of detection were approximately 4.5 and 0.75microgL(-1) for lead and cadmium, respectively. For a solution containing 100 and 10microgL(-1) of lead and cadmium, respectively, the R.S.D. values varied from 1.6 to 3.2% (n=7). The accuracy of the preconcentration system was evaluated by recovery measurements on spiked water samples. The method was susceptible to matrix effects, but these interferences were minimized by adding barium ions as masking agent in the sample solutions, and recoveries from spiked sample varied in the range of 95.1-107.3%.

  13. SELECTIVE TRACE ENRICHMENT BY IMMUNOAFFINITY CAPILLARY ELECTROCHROMATOGRAPHY ON-LINE WITH CAPILLARY ZONE ELECTROPHORESIS - LASER-INDUCED FLUORESCENCE

    EPA Science Inventory

    Limited by the lack of a sensitive, universal detector, many capillary-based liquid-phase separation techniques might benefit from techniques that overcome modest concentration sensitivity by preconcentrating large injection volumes. The work presented employs selective solid-ph...

  14. SELECTIVE TRACE ENRICHMENT BY IMMUNOAFFINITY CAPILLARY ELECTROCHROMATOGRAPHY ON-LINE WITH CAPILLARY ZONE ELECTROPHORESIS - LASER-INDUCED FLUORESCENCE

    EPA Science Inventory

    Limited by the lack of a sensitive, universal detector, many capillary-based liquid-phase separation techniques might benefit from techniques that overcome modest concentration sensitivity by preconcentrating large injection volumes. The work presented employs selective solid-ph...

  15. Preparation, characterization and application of Saussurea tridactyla Sch-Bip as green adsorbents for preconcentration of rare earth elements in environmental water samples

    NASA Astrophysics Data System (ADS)

    Zhang, Qiangying; He, Man; Chen, Beibei; Hu, Bin

    2016-07-01

    This paper deals with preparation, characterization and application of the Saussurea tridactyla Sch-Bip (STSB) as a new green adsorbent for separation of matrix elements and preconcentration of rare earth elements (REEs) in environmental water samples. The pretreated STSB adsorbent with 2 mol L- 1 NaOH is characterized with higher surface area and adsorption capacities in comparison with a raw STSB material. The new adsorbent was used for the development of on-line solid phase extraction (SPE) for the determination of REEs by radial viewing 27 MHz inductively coupled plasma optical emission spectrometry (ICP-OES). Various parameters affecting the adsorption/desorption procedure were optimized. The adsorption capacities for the STSB were found to be 62.2 (Y)-153 mg g- 1 (Tm). Under the optimized conditions, the limits of detection (LODs, 3σ) for REEs were in the range of 0.06 (Yb)-8.77 (Sm) ng mL- 1. The relative standard deviations (RSDs) for 7 replicate determinations of target REEs at low concentration level ranged from 2.4 (Yb) to 8.9 (Sm)%. The adsorption isotherm fitted Langmuir model and the adsorption kinetics fitted well with both Pseudo-first order and Pseudo-second order models. The predominant adsorption mechanism is ion exchange. The STSB pretreated with 2 mol L- 1 NaOH has been demonstrated to be low cost, green and environment friendly adsorbent, featuring with high adsorption capacity, wide pH range, and fast adsorption/desorption kinetics for target REEs with long lifetime. The proposed method was applied to the determination of REEs in East Lake, Yangtze River and rain water samples.

  16. Application of graphene for preconcentration and highly sensitive stripping voltammetric analysis of organophosphate pesticide.

    PubMed

    Wu, Shuo; Lan, Xiaoqin; Cui, Lijun; Zhang, Lihui; Tao, Shengyang; Wang, Hainan; Han, Mei; Liu, Zhiguang; Meng, Changgong

    2011-08-12

    Electrochemical reduced β-cyclodextrin dispersed graphene (β-CD-graphene) was developed as a sorbent for the preconcentration and electrochemical sensing of methyl parathion (MP), a representative nitroaromatic organophosphate pesticide with good redox activity. Benefited from the ultra-large surface area, large delocalized π-electron system and the superconductivity of β-CD-graphene, large amount of MP could be extracted on β-CD-graphene modified electrode via strong π-π interaction and exhibited fast accumulation and electron transfer rate. Combined with differential pulse voltammetric analysis, the sensor shows ultra-high sensitivity, good selectivity and fast response. The limit of detection of 0.05 ppb is more than 10 times lower than those obtained from other sorbent based sensors. The method may open up a new possibility for the widespread use of electrochemical sensors for monitoring of ultra-trace OPs.

  17. Spectroelectrochemical Sensor for Technetium: Preconcentration and Quantification of Technetium in Polymer Modified Electrodes

    SciTech Connect

    Monk, David J.; Stegemiller, Michael L.; Conklin, Sean; Paddock, Jean R.; Heineman, William R.; Seliskar, Carl J.; Ridgway, Thomas H.; Bryan, Samuel A.; Hubler, Tim L.

    2003-03-27

    A remote spectroelectrochemical sensor and instrumentation package is being developed for the detection of aqueous pertechnetate in the vadose zone. This sensor can be employed to monitor the integrity of low-level and high-level nuclear waste containment at U.S. DOE sites. A brief review of previous advancements and current development of this sensor is described. Initial spectroelectrochemical studies of pertechnetate using unmodified and polymer modified optically transparent electrodes have shown that the polymer modified electrode will readily preconcentrate pertechnetate. The electrodeposition of technetium oxide in these films is shown to be a method for the quantitative spectroelectrochemical determination of technetium and has been verified using radiochemistry dose measurements and scanning electron microscopy. The irreversible electrochemical nature of pertechnetate in polymer modified electrodes demonstrates the need to identify a ligand capable of complexing wi th technetium, to allow reversible detection and to provide additional chemical selectivity.

  18. Factorial design for multivariate optimization of preconcentration system for spectrophotometric phosphorus determination.

    PubMed

    Divrikli, Umit; Akdogan, Abdullah; Soylak, Mustafa; Elci, Latif

    2009-10-15

    The present paper proposes a preconcentration procedure for phosphorus determination by using ultraviolet-visible spectrophotometer. It is based on the formation of phosphomolybdate and its reduction to molybdenum blue. Phosphorus extraction as phosphomolybdenum blue complex was performed onto Amberlite XAD-4. The optimization step was carried out using two-level full factorial design. Three variables (resin amount, sample volume, flow rate) were regarded as factors in the optimization. The relative standard deviation was 2% at 0.08 microg mL(-1). The limit of detection was found to be 2.23 microg L(-1) (N=15). The proposed solid-phase extraction procedure was applied to phosphorus in some fruit leaves, natural waters, and a standard reference material (SRM 1515 apple leaves).

  19. Determination of thallium in wine by electrothermal atomic absorption spectrometry after extraction preconcentration

    NASA Astrophysics Data System (ADS)

    Cvetković, Julijana; Arpadjan, Sonja; Karadjova, Irina; Stafilov, Trajče

    2002-06-01

    A simple method for extraction electrothermal atomic absorption spectroscopy (ETAAS) determination of Tl in wine is described. The wine sample is decomposed with a mixture of nitric acid and hydrogen peroxide and both thallium species Tl(I) and Tl(III) are extracted from 0.5 mol l -1 KI solution into iso-butyl methyl ketone (IBMK). Optimal parameters for ETAAS measurement of the iodide complexes extracted were defined for two different instruments: Perkin Elmer Zeeman 3030 (HGA 600) and Varian SpectrAA-880 (GTA-100). Modifiers of tartaric acid, Pd [ammoniumtetrachloropaladate (II)] or Ag (silver nitrate) were investigated for thermal stabilization of such extremely volatile species as iodide complexes of Tl. The analytical procedure developed permits 50-fold preconcentration and determination of 0.05 μg l -1 Tl in wine. The relative standard deviation ranges from 6 to 12% for the concentration range 0.2-1 μg l -1 Tl in wine.

  20. Mass-spectrometric determination of trace elements in aqueous media without preconcentration

    SciTech Connect

    Foss, Gordon Oluf

    1981-10-01

    Feasibility of using a low pressure glow discharge as an ion source for the mass spectrometric determination of trace elements in aqueous media was investigated. A cryogenically cooled hollow cathode ion source was developed to analyze aqueous samples without external preconcentration. Aqueous solutions containing seventy elements were analyzed and the detection limits, sensitivity factors, and linear regression correlation coefficients were determined. A standard test solution of trace elements in water was analyzed and the concentrations of trace elements were calculated using the sensitivity factors determined previously. The results compared favorably within the error limits predicted by the semiquantitative survey methods used. Tap water and natural lake water samples were examined and minimal interference effects due to organic compounds and biological compounds were noted. A research ion optical system (RIOS) was developed as a flexible mass analyzer for the development of new ion sources. The RIOS is a double focussing mass analyzer designed utilizing the Mattauch-Herzog geometry with externally adjustable slit assemblies.

  1. Determination of trace lead in biological and water samples with dispersive liquid-liquid microextraction preconcentration.

    PubMed

    Liang, Pei; Sang, Hongbo

    2008-09-01

    A new method for the determination of trace lead was developed by dispersive liquid-liquid microextraction preconcentration and graphite furnace atomic absorption spectrometry. In the proposed approach, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) was used as a chelating agent, and carbon tetrachloride and ethanol were selected as extraction and dispersive solvents. Some factors influencing the extraction efficiency of lead and its subsequent determination, including extraction and dispersive solvent type and volume, pH of sample solution, concentration of the chelating agent, and extraction time, were studied and optimized. Under the optimum conditions, the enrichment factor of this method for lead was reached at 78. The detection limit for lead was 39 ng L(-1) (3 sigma), and the relative standard deviation (RSD) was 3.2% (n=7, c=10 ng mL(-1)). The method was successfully applied to the determination of trace amounts of lead in human urine and water samples.

  2. Cobalt preconcentration on a nitroso-R salt functional resin and elution with titanium(III)

    SciTech Connect

    Stella, R.; Valentini, M.T.G.; Maggi, L.

    1985-08-01

    The anion exchange resin Dowex 1X8, converted to the nitroso-R salt form, was used for adsorbing cobalt from large freshwater samples. Strongly acid titanium(III) chloride 10/sup -2/ M solution was found very effective at 60/sup 0/C as a new eluant and yielded complete recovery with a preconcentration factor of 100. Subsequent atomic absorption spectrometry determination of cobalt in the eluate was possible with no interference from titanium, reduced organics, and iron, copper, and nickel which partially might be fixed onto the resin. The suggested procedure allows a reproducibility of 5-10% for samples with cobalt concentrations in the range of 0.01-1 ..mu..g L/sup -1/. 15 references, 2 figures, 3 tables.

  3. Toward a microfabricated preconcentrator-focuser for a wearable micro-scale gas chromatograph.

    PubMed

    Bryant-Genevier, Jonathan; Zellers, Edward T

    2015-11-27

    This article describes work leading to a microfabricated preconcentrator-focuser (μPCF) designed for integration into a wearable microfabricated gas chromatograph (μGC) for monitoring workplace exposures to volatile organic compounds (VOCs) ranging in vapor pressure from ∼0.03 to 13kPa at concentrations near their respective Threshold Limit Values. Testing was performed on both single- and dual-cavity, etched-Si μPCF devices with Pyrex caps and integrated resistive heaters, packed with the graphitized carbons Carbopack X (C-X) and/or Carbopack B (C-B). Performance was assessed by measuring the 10% breakthrough volumes and injection bandwidths of a series of VOCs, individually and in mixtures, as a function of the VOC air concentrations, mixture complexity, sampling and desorption flow rates, adsorbent masses, temperature, and the injection split ratio. A dual-cavity device containing 1.4mg of C-X and 2.0mg of C-B was capable of selectively and quantitatively capturing a mixture of 14 VOCs at low-ppm concentrations in a few minutes from sample volumes sufficiently large to permit detection at relevant concentrations for workplace applications with the μGC detector that we ultimately plan to use. Thermal desorption at 225°C for 40s yielded ≥99% desorption of all analytes, and injected bandwidths as narrow as 0.6s facilitated efficient separation on a downstream 6-m GC column in <3min. A preconcentration factor of 620 was achieved for benzene from a sample of just 31mL. Increasing the mass of C-X to 2.3mg would be required for exhaustive capture of the more volatile target VOCs at high-ppm concentrations.

  4. Spectrophotometric detection of arsenic using flow-injection hydride generation following sorbent extraction preconcentration.

    PubMed

    Neto, J A; Montes, R; Cardoso, A A

    1999-12-06

    An automated system with a C(18) bonded silica gel packed minicolumn is proposed for spectrophotometric detection of arsenic using flow-injection hydride generation following sorbent extraction preconcentration. Complexes formed between arsenic(III) and ammonium diethyl dithiophosphate (ADDP) are retained on a C(18) sorbent. The eluted As-DDP complexes are merged with a 1.5% (w/v) NaBH(4) and the resulting solution is thereafter injected into the hydride generator/gas-liquid separator. The arsine generated is carried out by a stream of N(2) and trapped in an alkaline iodine solution in which the analyte is determined by the arsenomolybdenum blue method. With preconcentration time of 120 s, calibration in the 5.00-50.0 mug As l(-1) range and sampling rate of about 20 samples h(-1) are achieved, corresponding to 36 mg ADDP plus 36 mg ammonium heptamolybdate plus 7 mg hydrazine sulfate plus 0.7 mg stannous chloride and about 7 ml sample consumed per determination. The detection limit is 0.06 mug l(-1) and the relative standard deviation (n=12) for a typical 17.0 mug As l(-1) sample is ca. 6%. The accuracy was checked for arsenic determination in plant materials from the NIST (1572 citrus leaves; 1573 tomato leaves) and the results were in agreement with the certified values at 95% confidence level. Good recoveries (94-104%) of spiked tap waters, sugars and synthetic mixtures of trivalent and pentavalent arsenic were also found.

  5. Specificity of noble metals dynamic sorption preconcentration on reversed-phase sorbents.

    PubMed

    Fedyunina, N N; Seregina, I F; Ossipov, K; Dubenskiy, A S; Tsysin, G I; Bolshov, M A

    2013-10-10

    The reversible sorption preconcentration of noble metals (NMs) using different schemes "sorbent-reagent-eluent" was investigated. The extraction of Au, Pd, Pt, Ir, Rh and Ru chlorocomplexes from hydrochloric acid solutions on hyper-crosslinked polysterene MN-200 in the form of ion associates with tributylamine (TBA) and 4-(n-octyl)diethylenetriamine (ODETA) was investigated. It was found that Pd, Pt and Au were quantitatively and reversibly extracted using TBA on hyper-crosslinked polysterene; the appropriate eluent for desorption was 1M solution of HCl in ethanol. Ir, Rh and Ru under these conditions were not sorbed quantitatively. It was found that sorbent hydrophobicity is not the main characteristic that defines the efficiency of sorption of a particular NM ion associate. Different efficiencies of hyper-crosslinked polysterene MN-200 for sorption of square-planar chlorcomplexes of Pt, Pd and Au and octahedral complexes of Ir, Rh and Ru were found. For the first time, the sorbents with their own N-atoms - StrataX and StrataX-AW - were used for the sorption of Ir, Rh and Ru. Using these sorbents, the sorption of Ir was increased up to 95%, and the sorption of Ru and Rh was increased to about 40%. We can explain these results by nonspecific interaction of chlorcomplexes of Ir, Rh and Ru with ethylenediamine groups of the sorbent. Weak bases with large anions may be applied for desorption of Ir, Rh and Ru. Two schemes of dynamic sorption preconcentration of NMs from hydrochloric acid solutions were proposed - hyper-crosslinked polysterene MN-200 for the determination of Au, Pd, Pt, and StrataX-AW for Ir, Rh and Ru.

  6. Evaluation of functionalized isoreticular metal organic frameworks (IRMOFs) as smart nanoporous preconcentrators of RDX

    SciTech Connect

    Xiong, Ruichang; Odbadrakh, Khorgolkhuu; Michalkova, Andrea; Luna, Johnathan P.; Petrova, Tetyana; Keffer, David J.; Nicholson, Don M; Fuentes-Cabrera, Miguel A; Lewis, James; Leszczynski, Jerzy

    2010-01-01

    Classical molecular dynamics (MD) and Grand Canonical Monte Carlo (GCMC) simulations were used to generate self-diffusivities, adsorption isotherms and density distributions for hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in five isoreticular metal-organic frameworks (IRMOFs), which varied in the cage size and in the presence and location of amine groups. These simulations were performed at room temperature (300 K) and low pressures (up to 1 ppm RDX). The atomic charges required for MD and GCMC simulations were calculated from quantum mechanical (QM) calculations using two different charge generation methods - Loewdin Population Analysis and Natural Bond Orbital Analysis. Both charge sets show that the presence of amine groups increases the amount of RDX adsorbed. The cage size and the location of amine groups also affect the loading of RDX. The amount of RDX adsorbed is correlated with the energy of adsorption. The activation energy for diffusion of RDX is not positively correlated with the energy of adsorption. The density distributions identify the location of the adsorption sites of RDX-exclusively in the big cage around the metal complex vertices and between benzene rings. In the absence of amine groups on the framework, one of nitro groups on RDX interacts closely with the metal complex. In the IRMOFs functionalized with amine groups, a second nitro group of the RDX interacts with an amine group, enhancing adsorption. With regard to the application as a smart nanoporous preconcentrator, these IRMOFs are found to concentrate RDX up to 3000 times compared to the gas phase, on a volumetric basis. From a simple Langmuir estimation, the selectivity of RDX over butane is up to 5000. The diffusion of RDX is sufficiently high for real time sensor applications. These results indicate IRMOFs can be tailored with functional groups to be highly selective nanoporous preconcentrators.

  7. Development of micromachined preconcentrators and gas chromatographic separation columns by an electroless gold plating technology

    NASA Astrophysics Data System (ADS)

    Kuo, C.-Y.; Chen, P.-S.; Chen, H.-T.; Lu, C.-J.; Tian, W.-C.

    2017-03-01

    In this study, a simple process for fabricating a novel micromachined preconcentrator (μPCT) and a gas chromatographic separation column (μSC) for use in a micro gas chromatograph (μGC) using one photomask is described. By electroless gold plating, a high-surface-area gold layer was deposited on the surface of channels inside the μPCT and μSC. For this process, (3-aminopropyl) trimethoxysilane (APTMS) was used as a promoter for attaching gold nanoparticles on a silicon substrate to create a seed layer. For this purpose, a gold sodium sulfite solution was used as reagent for depositing gold to form heating structures. The microchannels of the μPCT and μSC were coated with the adsorbent and stationary phase, Tenax-TA and polydimethylsiloxane (DB-1), respectively. μPCTs were heated at temperatures greater than 280 °C under an applied electrical power of 24 W and a heating rate of 75 °C s-1. Repeatable thermal heating responses for μPCTs were achieved; good linearity (R 2  >  0.9997) was attained at three heating rates for the temperature programme for the μSC (0.2, 0.5 and 1 °C s-1). The volatile organic compounds (VOCs) toluene and m-xylene were concentrated over the μPCT by rapid thermal desorption (peak width of half height (PWHH)  <1.5 s) preconcentration factors for both VOCs are  >7900. The VOCs acetone, benzene, toluene, m-xylene and 1,3,5-trimethylbenzene were also separated on the μSC as evidenced by their different retention times (47-184 s).

  8. Simultaneous determination of selected endocrine disrupters (pesticides, phenols and phthalates) in water by in-field solid-phase extraction (SPE) using the prototype PROFEXS followed by on-line SPE (PROSPEKT) and analysis by liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry.

    PubMed

    López-Roldán, P; López de Alda, M J; Barceló, D

    2004-02-01

    In this study, a new procedure, based on on-line solid-phase extraction (SPE) and analysis by liquid-chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS), has been developed for the simultaneous, multianalyte determination of 21 selected pesticides, phenols and phthalates in water. SPE was carried out on polymeric PLRP-s cartridges by percolating 20 mL-samples. For sample preconcentration, the performance of a prototype programmable field extraction system (PROFEXS) was evaluated against the commercial laboratory bench Prospekt system used for method development. The Profexs is designed for the automated on-site sampling, SPE preconcentration, and storage of up to 16 samples in SPE cartridges. These cartridges are further eluted and on-line analyzed with the Prospekt coupled to the chromatographic system. In the optimized method, where completely on-line SPE-LC-MS analysis of the samples is carried out with the Prospekt in the laboratory, detection limits lower than 100 ng/L, and satisfactory precision (relative standard deviations <25%) and accuracies (recovery percentages >75%) were obtained for most investigated compounds from the analysis of spiked Milli-Q water. The extraction efficiency achieved with the Profexs was comparable to that of the Prospekt for most compounds and somewhat lower for the most apolar analytes, probably due to adsorption on the pump filters. The completely on-line optimized method was applied to the analysis of surface water, ground water and drinking water from a waterworks in Barcelona. Some pesticides and phenols were found in both surface water and groundwater at ng/L or microg/L levels, but not in the final drinking water. Di(2-ethylhexyl)phthalate (DEHP) was present in all samples investigated, including blanks. To the author's knowledge, this is the first work describing the application of a fully automated on-line SPE-LC-MS method for the simultaneous analysis of pesticides, phenols, and

  9. A Refreshable, On-line Cache for HST Data Retrieval

    NASA Astrophysics Data System (ADS)

    Fraquelli, Dorothy A.; Ellis, Tracy A.; Ridgaway, Michael; DPAS Team

    2016-01-01

    We discuss upgrades to the HST Data Processing System, with an emphasis on the changes Hubble Space Telescope (HST) Archive users will experience. In particular, data are now held on-line (in a cache) removing the need to reprocess the data every time they are requested from the Archive. OTFR (on the fly reprocessing) has been replaced by a reprocessing system, which runs in the background. Data in the cache are automatically placed in the reprocessing queue when updated calibration reference files are received or when an improved calibration algorithm is installed. Data in the on-line cache are expected to be the most up to date version. These changes were phased in throughout 2015 for all active instruments.The on-line cache was populated instrument by instrument over the course of 2015. As data were placed in the cache, the flag that triggers OTFR was reset so that OTFR no longer runs on these data. "Hybrid" requests to the Archive are handled transparently, with data not yet in the cache provided via OTFR and the remaining data provided from the cache. Users do not need to make separate requests.Users of the MAST Portal will be able to download data from the cache immediately. For data not in the cache, the Portal will send the user to the standard "Retrieval Options Page," allowing the user to direct the Archive to process and deliver the data.The classic MAST Search and Retrieval interface has the same look and feel as previously. Minor changes, unrelated to the cache, have been made to the format of the Retrieval Options Page.

  10. Key-linked on-line databases for clinical research.

    PubMed

    Müller, Thomas H

    2012-01-01

    Separating patient identification data from clinical data and/or information about biomaterial samples is an effective data protection measure, especially in clinical research employing "on-line", i.e., web-based, data capture. In this paper, we show that this specialised technique can be generalised into a network architecture of interconnected on-line databases potentially serving a variety of purposes. The basic idea of this approach consists of maintaining logical links, i.e., common record keys, between corresponding data structures in pairs of databases while keeping the actual key values hidden from clients. For client systems, simultaneous access to corresponding records is mediated by temporary access tokens. At the relational level, these links are represented by arbitrary unique record keys common to both databases. This architecture allows for integration of related data in different databases without replicating or permanently sharing this data in one place. Each participating on-line database can determine the degree of integration by specifying linkage keys only for those data structures that may be logically connected to other data. Logical links can de designed for specific use cases. In addition, each database controls user access by enforcing its own authorisation scheme. Another advantage is that individual database owners retain considerable leeway in adapting to changing local requirements without compromising the integration into the network. Beyond protecting individual subject identification data, this architecture permits splitting a cooperatively used data pool to achieve many kinds of objectives. Application examples could be clinical registries needing subject contact information for follow-up, biomaterial banks with or without genetic information, and automatic or assisted integration of data from electronic medical records into research data.

  11. On-line estimation of biodegradation in an unsaturated soil.

    PubMed

    Schoefs, O; Perrier, M; Dochain, D; Samson, R

    2003-11-01

    The objective of this study was to develop a model-based estimator of biodegradation in unsaturated soil. This would allow real-time assessment of the efficiency of treatment bioprocesses, such as bioventilation and biopile, and eventually permit optimization through the implementation of control strategies. Based on a reduced-order model, an asymptotic observer was designed to estimate on-line the contaminant concentration, using carbon dioxide measurement. Two observer-based estimators were built to approximate: (1) the specific microbial growth rate; and (2) the biocontact kinetics representing the soil resistance to contaminant biodegradation. State observers and parameter estimators were confronted with the experimental results of biodegradation in microcosms. Hexadecane was used as the model compound, representing petroleum hydrocarbons. Three water contents, corresponding to 20%, 50% and 80% of the water-holding capacity, were tested. The asymptotic observer is able to predict hexadecane depletion with an error on the overall time trajectories of 13%, 8% and 4% for the dry, intermediate and wet soils, respectively, which is acceptable given that all the biokinetic parameters were identified from a biodegradation experiment in liquid phase. The observer-based estimator of the specific microbial growth rate, based on the CO(2) measurement, was successfully calibrated using the off-line measurements of hexadecane as validation data, and allowed estimation of the time when biodegradation switched from a microbial to a biocontact limitation. The biocontact kinetics was also identified on-line, using an estimator based on the hexadecane not in biocontact. These results are very encouraging with respect to the potential for on-line assessment of the performance of treatment bioprocesses in unsaturated soils.

  12. In the Jungle of Astronomical On--line Data Services

    NASA Astrophysics Data System (ADS)

    Egret, D.

    The author tried to survive in the jungle of astronomical on--line data services. In order to find efficient answers to common scientific data retrieval requests, he had to collect many pieces of information, in order to formulate typical user scenarios, and try them against a number of different data bases, catalogue services, or information systems. He discovered soon how frustrating treasure coffers may be when their keys are not available, but he realized also that nice widgets and gadgets are of no help when the information is not there. And, before long, he knew he would have to navigate through several systems because no one was yet offering a general answer to all his questions. I will present examples of common user scenarios and show how they were tested against a number of services. I will propose some elements of classification which should help the end-user to evaluate how adequate the different services may be for providing satisfying answers to specific queries. For that, many aspects of the user interaction will be considered: documentation, access, query formulation, functionalities, qualification of the data, overall efficiency, etc. I will also suggest possible improvements to the present situation: the first of them being to encourage system managers to increase collaboration between one another, for the benefit of the whole astronomical community. The subjective review I will present, is based on publicly available astronomical on--line services from the U.S. and from Europe, most of which (excepting the newcomers) were described in ``Databases and On-Line Data in Astronomy", (Albrecht & Egret, eds, 1991): this includes databases (such as NED and Simbad ), catalog services ( StarCat , DIRA , XCatScan , etc.), and information systems ( ADS and ESIS ).

  13. On-line monitoring and analysis of reactor vessel integrity

    SciTech Connect

    Ackerson, D.S.; Impink, A.J. Jr.; Balkey, K.R.; Andreychek, T.S.

    1989-01-31

    A method is described for on-line monitoring and analysis of nuclear reactor pressure vessel integrity in a unit in which reactor coolant is circulated along the inner wall of the pressure vessel, the method comprising the steps of: generating on an on-line basis, temperature signals representative of the temperature of the reactor coolant circulating along the inner wall of the pressure vessel; generating on an on-line basis, a pressure signal representative of the reactor coolant pressure; generating a signal representative of fast neutron fluence to which the reactor pressure vessel has been subjected; generating as a function of the fluence signal a visual representation of the actual real time reference nil-ductibility transition temperature (RT/sub ndt/) across the entire pressure vessel wall thickness at a preselected critical location in the wall; generating as a function of transients in the reactor coolant temperature and pressur signals, a visual representation of the real time required RT/sub ndt/, across the entire pressure vessel wall thickness at the selected critical location, the required RT/sub ndt/ being the RT/sub ndt/ that would be required in the pressure vessel wall for flaw initiation to occur as a result of stresses set-up by the transients; and superimposing the visual representations of the real-time actual and required RT/sub ndt's/ for flaw initiation across the entire pressure vessel wall thickness for the selected critical location to generate a visual representation of the difference in value between the actual and required RT/sub ndt/ presented as an RT/sub ndt/ margin.

  14. On-line distortion analysis system inlet-engine test

    SciTech Connect

    Morton, W.K.; Lazalier, G.R.; Rose, C.D.; Lauer, R.F.

    1991-06-01

    A system for near-real-time distortion analysis support of aircraft turbine engine-inlet altitude testing is described. Target applications include both subscale and full-scale inlet-engine compatibility testing in wind tunnel, direct-connect, and free-jet configurations. The system digitizes analog-format, time-dependent data and combines it with digital-format, steady-state data. A high-speed data bus and multiple array processors provide for on-line execution of complex distortion analysis algorithms to compute and display distortion indices, histograms, isobar plots, and surge margin consumption. Analysis algorithms are programmed using a high-level language (FORTRAN 77).

  15. TELCAL: The On-line Calibration Software for ALMA

    NASA Astrophysics Data System (ADS)

    Broguière, D.; Lucas, R.; Pardo, J.; Roche, J.-C.

    2011-07-01

    The ALMA on-line calibration regroups all the operations needed to maintain the ALMA interferometer optimally tuned to successfully execute the planned observations. The results of the calibrations are used in quasi-real time by the ALMA Control System. Since the first ALMA antennas were put into operation in 2009, TELCAL has been used for all the basic calibration operations and is still being improved following the project advancement. We describe here the calibrations done by TELCAL, its relationships with the other ALMA software subsystems and, briefly, the architecture of the software based on CORBA.

  16. Anisotropic alpha emission from on-line separated isotopes

    SciTech Connect

    Wouters, J.; Vandeplassche, D.; van Walle, E.; Severijns, N.; Vanneste, L.

    1986-05-05

    A systematic on-line nuclear-orientation study of heavy isotopes using anisotropic ..cap alpha.. emission is reported for the first time. The anisotrophies recorded for /sup 199/At, /sup 201/At, and /sup 203/At are remarkably pronounced and strongly varying. At lower neutron number the ..cap alpha.. particles are more preferentially emitted perpendicularly to the nuclear-spin direction. This may be interpreted in terms of the high sensitivity of the ..cap alpha..-emission probability to changes in the nuclear shape.

  17. On-line infrared process signature measurements through combustion atmospheres

    NASA Astrophysics Data System (ADS)

    Zweibaum, F. M.; Kozlowski, A. T.; Surette, W. E., Jr.

    1980-01-01

    A number of on-line infrared process signature measurements have been made through combustion atmospheres, including those in jet engines, piston engines, and coal gasification reactors. The difficulties involved include operation in the presence of pressure as high as 1800 psi, temperatures as high as 3200 F, and explosive, corrosive and dust-laden atmospheres. Calibration problems have resulted from the use of purge gases to clear the viewing tubes, and the obscuration of the view ports by combustion products. A review of the solutions employed to counteract the problems is presented, and areas in which better solutions are required are suggested.

  18. Source reduction from chemical plants using on-line optimization

    SciTech Connect

    Zhang, Z.; Pike, R.W.; Hertwig, T.A.

    1995-12-01

    An effective approach for source reduction in chemical plants has been demonstrated using on-line optimization with flowsheeting (ASPEN PLUS) for process optimization and parameter estimation and the Tjao-Biegler algorithm implemented in a mathematical programming language (GAMS/MINOS) for data reconciliation and gross error detection. Results for a Monsanto sulfuric acid plant with a Bailey distributed control system showed a 25% reduction in the sulfur dioxide emissions and a 17% improvement in the profit over the current operating conditions. Details of the methods used are described.

  19. On-line Monitoring and Active Control for Transformer Noise

    NASA Astrophysics Data System (ADS)

    Liang, Jiabi; Zhao, Tong; Tian, Chun; Wang, Xia; He, Zhenhua; Duan, Lunfeng

    This paper introduces the system for on-line monitoring and active noise control towards the transformer noise based on LabVIEW and the hardware equipment including the hardware and software. For the hardware part, it is mainly focused on the composition and the role of hardware devices, as well as the mounting location in the active noise control experiment. And the software part introduces the software flow chats, the measurement and analysis module for the sound pressure level including A, B, C weighting methods, the 1/n octave spectrum and the power spectrum, active noise control module and noise data access module.

  20. Anisotropic. cap alpha. -emission of on-line separated isotopes

    SciTech Connect

    Wouters, J.; Vandeplassche, D.; van Walle, E.; Severijns, N.; Van Haverbeke, J.; Vanneste, L.

    1987-12-10

    The technical realization of particle detection at very low temperatures (4K) has made it possible to study for the first time the anisotropic ..cap alpha..-decay of oriented nuclei which have been produced, separated and implanted on line. The measured ..cap alpha..-angular distributions reveal surprising new results on nuclear aspects as well as in solid state physics. The nuclear structure information from these data questions the older ..cap alpha..-decay theoretical interpretation and urges for a reaxamination of the earliest work on anisotropic ..cap alpha..-decay.

  1. Molecularly imprinted polymers for on-line extraction techniques.

    PubMed

    Moein, Mohammad M; Abdel-Rehim, Mohamed

    2015-01-01

    Recent years have seen an increasing interest in the use of molecularly imprinted polymers (MIPs) as a sorbent for different extraction methods and this is due to its high selectivity. The MIP is designed to show specificity for the analyte of interest. Moreover, MIPs show physical robustness, resistance to high temperatures and pressures, and stability in the presence of acids, bases and a wide range of organic solvents. In the present article, various novel sample preparation techniques which MIPs applied as sorbent and on-line connected with analytical instruments were highlighted and discussed. The future aspects of MIPs as well were described.

  2. Some aspects of analytical chemistry as applied to water quality assurance techniques for reclaimed water: The potential use of X-ray fluorescence spectrometry for automated on-line fast real-time simultaneous multi-component analysis of inorganic pollutants in reclaimed water

    NASA Technical Reports Server (NTRS)

    Ling, A. C.; Macpherson, L. H.; Rey, M.

    1981-01-01

    The potential use of isotopically excited energy dispersive X-ray fluorescence (XRF) spectrometry for automated on line fast real time (5 to 15 minutes) simultaneous multicomponent (up to 20) trace (1 to 10 parts per billion) analysis of inorganic pollutants in reclaimed water was examined. Three anionic elements (chromium 6, arsenic and selenium) were studied. The inherent lack of sensitivity of XRF spectrometry for these elements mandates use of a preconcentration technique and various methods were examined, including: several direct and indirect evaporation methods; ion exchange membranes; selective and nonselective precipitation; and complexation processes. It is shown tha XRF spectrometry itself is well suited for automated on line quality assurance, and can provide a nondestructive (and thus sample storage and repeat analysis capabilities) and particularly convenient analytical method. Further, the use of an isotopically excited energy dispersive unit (50 mCi Cd-109 source) coupled with a suitable preconcentration process can provide sufficient sensitivity to achieve the current mandated minimum levels of detection without the need for high power X-ray generating tubes.

  3. Advances in fuel management and on-line core monitoring

    SciTech Connect

    Stout, R.B.; Hansen, L.E.; Patten, T.W.

    1988-01-01

    Advanced Nuclear Fuels Corporation (ANF) has developed and implemented advanced core power distribution monitoring methods for BWRs and PWRs based on the three dimensional nodal simulator codes used for incore fuel management design and analysis. The use of these methods has resulted in a more accurate assessment of the core power distribution and corresponding increased operating margins. These increased margins allow for more economical fuel cycle designs. Since the initial application in 1982, ANF has made enhancements to the incore monitoring system. These enhancements have permitted more rapid analysis of local power changes, power distribution projections during ascent to full power and on-line statistical analysis of the incore detector signal. The on-line analysis implemented in BWRs has also been developed for application PWRs. In the future, reactors are expected to operate with longer fuel cycles, more aggressive low radial leakage loadings, load follow and use higher burnup fuel. These advances will require more burnable neutron absorbers and more sophisticated fuel designs. To accommodate these advances, the fuel management methodologies and measurement system will require improvements. The state-of-the-art methods provided by ANF provide incore monitoring systems compatible with these expected needs.

  4. Polar On-Line Acquisition Relay and Transmission System (POLARATS)

    SciTech Connect

    Yuracko, K.

    2004-07-15

    POLARATS (Polar On-Line Acquisition Relay And Transmission System) is being developed by YAHSGS LLC (YAHSGS) and Oak Ridge National Laboratory (ORNL) to provide remote, unattended monitoring of environmental parameters under harsh environmental conditions. In particular, instrumental design and engineering is oriented towards protection of human health in the Arctic, and with the additional goal of advancing Arctic education and research. POLARATS will obtain and transmit environmental data from hardened monitoring devices deployed in locations important to understanding atmospheric and aquatic pollutant migration as it is biomagnified in Arctic food chains. An Internet- and personal computer (PC)-based educational module will provide real time sensor data, on-line educational content, and will be integrated with workbooks and textbooks for use in middle and high school science programs. The educational elements of POLARATS include an Internet-based educational module that will instruct students in the use of the data and how those data fit into changing Arctic environments and food chains. POLARATS will: (1) Enable students, members of the community, and scientific researchers to monitor local environmental conditions in real time over the Internet; and (2) Provide additional educational benefits through integration with middle- and high-school science curricula. Information will be relayed from POLARATS devices to classrooms and libraries along with custom-designed POLARATS teaching materials that will be integrated into existing curricula to enhance the educational benefits realized from the information obtained.

  5. Increased cortical thickness in professional on-line gamers.

    PubMed

    Hyun, Gi Jung; Shin, Yong Wook; Kim, Bung-Nyun; Cheong, Jae Hoon; Jin, Seong Nam; Han, Doug Hyun

    2013-12-01

    The bulk of recent studies have tested whether video games change the brain in terms of activity and cortical volume. However, such studies are limited by several factors including cross-sectional comparisons, co-morbidity, and short-term follow-up periods. In the present study, we hypothesized that cognitive flexibility and the volume of brain cortex would be correlated with the career length of on-line pro-gamers. High-resolution magnetic resonance scans were acquired in twenty-three pro-gamers recruited from StarCraft pro-game teams. We measured cortical thickness in each individual using FreeSurfer and the cortical thickness was correlated with the career length and the performance of the pro-gamers. CAREER LENGTH WAS POSITIVELY CORRELATED WITH CORTICAL THICKNESS IN THREE BRAIN REGIONS: right superior frontal gyrus, right superior parietal gyrus, and right precentral gyrus. Additionally, increased cortical thickness in the prefrontal cortex was correlated with winning rates of the pro-game league. Increased cortical thickness in the prefrontal and parietal cortices was also associated with higher performance of Wisconsin Card Sorting Test. Our results suggest that in individuals without pathologic conditions, regular, long-term playing of on-line games is associated with volume changes in the prefrontal and parietal cortices, which are associated with cognitive flexibility.

  6. On-line inverse multiple instance boosting for classifier grids

    PubMed Central

    Sternig, Sabine; Roth, Peter M.; Bischof, Horst

    2012-01-01

    Classifier grids have shown to be a considerable choice for object detection from static cameras. By applying a single classifier per image location the classifier’s complexity can be reduced and more specific and thus more accurate classifiers can be estimated. In addition, by using an on-line learner a highly adaptive but stable detection system can be obtained. Even though long-term stability has been demonstrated such systems still suffer from short-term drifting if an object is not moving over a long period of time. The goal of this work is to overcome this problem and thus to increase the recall while preserving the accuracy. In particular, we adapt ideas from multiple instance learning (MIL) for on-line boosting. In contrast to standard MIL approaches, which assume an ambiguity on the positive samples, we apply this concept to the negative samples: inverse multiple instance learning. By introducing temporal bags consisting of background images operating on different time scales, we can ensure that each bag contains at least one sample having a negative label, providing the theoretical requirements. The experimental results demonstrate superior classification results in presence of non-moving objects. PMID:22556453

  7. On-line diagnosis of sequential systems, 3

    NASA Technical Reports Server (NTRS)

    Sundstrom, R. J.

    1975-01-01

    A formal model is introduced which can serve as the basis for a theoretical investigation of on-line diagnosis. Within this model a fault of a system S is considered to be a transformation of S into another system S prime at some time tau. The resulting faulty system is taken to be the system which looks like S up to time tau and like S prime thereafter. The on-line diagnosis of systems which are structurally decomposed and represented as a network of smaller systems is also investigated. The fault set considered is the set of unrestricted component faults; namely, the set of faults which only affect one component of the network. A characterization of networks which can be diagnosed using a combinational detector is obtained. It is further shown that any network can be made diagnosable in the above sense through the addition of one component. In addition, a lower bound is obtained on the complexity of any component, the addition of which is sufficient to make a particular network combinationally diagnosable.

  8. Fully On-line Introductory Physics with a Lab

    NASA Astrophysics Data System (ADS)

    Schatz, Michael

    We describe the development and implementation of a college-level introductory physics (mechanics) course and laboratory that is suited for both on-campus and on-line environments. The course emphasizes a ``Your World is Your Lab'' approach whereby students first examine and capture on video (using cellphones) motion in their immediate surroundings, and then use free, open-source software both to extract data from the video and to apply physics principles to build models that describe, predict, and visualize the observations. Each student reports findings by creating a video lab report and posting it online; these video lab reports are then distributed to the rest of the class for peer review. In this talk, we will discuss the student and instructor experiences in courses offered to three distinct audiences in different venues: (1) a Massively Open On-line Course (MOOC) for off-campus participants, (2) a flipped/blended course for on-campus students, and, most recently, (3) a fully-online course for off-campus students.

  9. Pulsed Neurton Elemental On-Line Material Analyzer

    DOEpatents

    Vourvopoulos, George

    2002-08-20

    An on-line material analyzer which utilizes pulsed neutron generation in order to determine the composition of material flowing through the apparatus. The on-line elemental material analyzer is based on a pulsed neutron generator. The elements in the material interact with the fast and thermal neutrons produced from the pulsed generator. Spectra of gamma-rays produced from fast neutrons interacting with elements of the material are analyzed and stored separately from spectra produced from thermal neutron reactions. Measurements of neutron activation takes place separately from the above reactions and at a distance from the neutron generator. A primary passageway allows the material to flow through at a constant rate of speed and operators to provide data corresponding to fast and thermal neutron reactions. A secondary passageway meters the material to allow for neutron activation analysis. The apparatus also has the capability to determine the density of the flowed material. Finally, the apparatus continually utilizes a neutron detector in order to normalize the yield of the gamma ray detectors and thereby automatically calibrates and adjusts the spectra data for fluctuations in neutron generation.

  10. Increased Cortical Thickness in Professional On-Line Gamers

    PubMed Central

    Hyun, Gi Jung; Shin, Yong Wook; Kim, Bung-Nyun; Cheong, Jae Hoon; Jin, Seong Nam

    2013-01-01

    Objective The bulk of recent studies have tested whether video games change the brain in terms of activity and cortical volume. However, such studies are limited by several factors including cross-sectional comparisons, co-morbidity, and short-term follow-up periods. In the present study, we hypothesized that cognitive flexibility and the volume of brain cortex would be correlated with the career length of on-line pro-gamers. Methods High-resolution magnetic resonance scans were acquired in twenty-three pro-gamers recruited from StarCraft pro-game teams. We measured cortical thickness in each individual using FreeSurfer and the cortical thickness was correlated with the career length and the performance of the pro-gamers. Results Career length was positively correlated with cortical thickness in three brain regions: right superior frontal gyrus, right superior parietal gyrus, and right precentral gyrus. Additionally, increased cortical thickness in the prefrontal cortex was correlated with winning rates of the pro-game league. Increased cortical thickness in the prefrontal and parietal cortices was also associated with higher performance of Wisconsin Card Sorting Test. Conclusion Our results suggest that in individuals without pathologic conditions, regular, long-term playing of on-line games is associated with volume changes in the prefrontal and parietal cortices, which are associated with cognitive flexibility. PMID:24474988

  11. Precise on-line position measurement for particle therapy

    NASA Astrophysics Data System (ADS)

    Actis, O.; Meer, D.; König, S.

    2014-12-01

    An on-line beam position monitoring and regular beam stability tests are of utmost importance for the Quality Assurance (QA) of the patient treatment at any particle therapy facility. The Gantry 2 at the Paul Scherrer Institute uses a strip ionization chamber for the on-line beam position verification. The design of the strip chamber placed in the beam in front of the patient allows for a small beam penumbra in order to achieve a high-quality lateral beam delivery. The position error of 1 mm in a lateral plane (plane perpendicular to the beam direction) can result in a dose inhomogeneity of more than 5%. Therefore the goal of Gantry 2 commissioning was to reach a sub-millimeter level of the reconstruction accuracy in order to bring a dose uncertainty to a level of 1%. In fact, we observed that for beams offered by Gantry 2 signal profiles in a lateral plane can be reconstructed with a precision of 0.1 mm. This is a necessary criterion to perform a reliable patient treatment. The front end electronics and the whole data processing sequence have been optimized for minimizing the dead time in between two consecutive spots to about 2 ms: the charge collection is performed in about 1 ms, read-out takes place in about 100μs while data verification and logging are completed in less than 1 ms.

  12. On-line visual control of grasping movements.

    PubMed

    Volcic, Robert; Domini, Fulvio

    2016-08-01

    Even though it is recognized that vision plays an important role in grasping movements, it is not yet fully understood how the visual feedback of the hand contributes to the on-line control. Visual feedback could be used to shape the posture of the hand and fingers, to adjust the trajectory of the moving hand, or a combination of both. Here, we used a dynamic perturbation method that altered the position of the visual feedback relative to the actual position of the thumb and index finger to virtually increase or decrease the visually sensed grip aperture. Subjects grasped objects in a virtual 3D environment with haptic feedback and with visual feedback provided by small virtual spheres anchored to the their unseen fingertips. We found that the effects of the visually perturbed grip aperture arose preeminently late in the movement when the hand was in the object's proximity. The on-line visual feedback assisted both the scaling of the grip aperture to properly conform it to the object's dimension and the transport of the hand to correctly position the digits on the object's surface. However, the extent of these compensatory adjustments was contingent on the viewing geometry. The visual control of the actual grip aperture was mainly observed when the final grasp axis orientation was approximately perpendicular to the viewing direction. On the contrary, when the final grasp axis was aligned with the viewing direction, the visual control was predominantly concerned with the guidance of the digit toward the visible final contact point.

  13. On-line social interactions and executive functions

    PubMed Central

    Ybarra, Oscar; Winkielman, Piotr

    2012-01-01

    A successful social interaction often requires on-line and active construction of an ever-changing mental-model of another person’s beliefs, expectations, emotions, and desires. It also requires the ability to maintain focus, problem-solve, and flexibly pursue goals in a distraction-rich environment, as well as the ability to take-turns and inhibit inappropriate behaviors. Many of these tasks rely on executive functions (EF) – working memory, attention/cognitive control, and inhibition. Executive functioning has long been viewed as relatively static. However, starting with recent reports of successful cognitive interventions, this view is changing and now EFs are seen as much more open to both short- and long-term “training,” “warm-up,” and “exhaustion” effects. Some of the most intriguing evidence suggests that engaging in social interaction enhances performance on standard EF tests. Interestingly, the latest research indicates these EF benefits are selectively conferred by certain on-line, dynamic social interactions, which require participants to mentally engage with another person and actively construct a model of their mind. We review this literature and highlight its connection with evolutionary and cultural theories emphasizing links between intelligence and sociality. PMID:22509160

  14. On-line measurements of diesel nanoparticle composition and volatility

    NASA Astrophysics Data System (ADS)

    Sakurai, Hiromu; Tobias, Herbert J.; Park, Kihong; Zarling, Darrick; Docherty, Kenneth S.; Kittelson, David B.; McMurry, Peter H.; Ziemann, Paul J.

    A thermal desorption particle beam mass spectrometer (TDPBMS) and tandem differential mobility analyzers (TDMA) were used for on-line measurements of the chemical composition and volatility of nanoparticles and larger particles emitted from a modern, heavy-duty diesel engine operated at light and medium loads under laboratory conditions. Temperature-dependent TDPBMS mass spectra and mass spectra obtained using spectrally distinctive oil and synthetic Fischer-Tropsch fuel were analyzed using mass spectral matching methods to obtain quantitative information on the contributions of fuel, oil, oxidation products, and sulfuric acid to particle composition. TDMA measurements of volatility yielded information on nanoparticle vapor pressures and therefore on the composition of organic components. The results indicate that, for these operating conditions, the volatile component of both diesel nanoparticles and larger particles is comprised of at least 95% unburned lubricating oil. TDMA volatility measurements also detected residual species a few nanometers in diameter, which may be non-volatile cores (soot, metal oxide) or low-volatility organic compounds. These on-line analyses provide new insights into the mechanisms of diesel nanoparticle formation.

  15. Experimental on-line identification of an electromechanical system.

    PubMed

    Eker, Ilyas

    2004-01-01

    Identification of electromechanical systems operating in open-loop or closed-loop conditions has long been of prime interest in industrial applications. This paper presents experimental on-line identification of an electromechanical system represented by a digital input/output model. The paper also bridges the theory and practice gap for applied researchers. Studies are carried out by formulating the mathematical model using differential equations and experimental discrete-time identification using on-line plant input-output data. A recursive least-squares method is used to estimate the unknown parameters of the system. Discrete-time data for the parameter identification are obtained experimentally from a setup constructed in the laboratory. A root-mean-square error criterion is used for model validation. Results are presented which show variations in parameters of the electromechanical system. It is demonstrated that identified model output and actual system output match. All tests are performed with no previous results from finite element simulations.

  16. Data warehousing features in Informix OnLine XPS

    SciTech Connect

    Sundaresan, P.

    1996-12-31

    The Data Warehousing application domain is an important area of focus for Informix`s OnLine XPS massively parallel server. Fast query processing is a central requirement in this domain. Use of indexes has traditionally been an important query processing technique, helping to reduce response times and increase throughput. The data warehousing environment, characterized by its load-query-refresh mode of operation, offers even greater scope for use of indexes. This talk will describe three new indexing related features in OnLine XPS which together provide significant performance benefits in a wide variety of situations. Bitmap indexes, along with multi-index scans, provide orders-of-magnitude improvement for queries typified by the Set Query Benchmark. Pushdown Semi-joins combine the benefits of multi-index scans with the scalability of hash joins to efficiently process star-joins. Finally, Generalized-key indexes expand the notion of what can be an index key and provide the ability to store various pre-computed results in an index. Optimizer extensions allow these features to be used in a mix-n-match fashion, thus maximizing the benefits of these features while minimizing the need for user level directives.

  17. Porous monoliths for on-line sample preparation: A review.

    PubMed

    Masini, Jorge C; Svec, Frantisek

    2017-04-29

    This review aims at presenting the state of the art concerning monolithic materials for on-line sample preparation emphasizing solid-phase extraction, matrix exchange, and analyte conversion. Emphasis was given to organic and silica-based, as well as hybrid monoliths reported in the literature mostly after 2010. The first part of this review presents materials and strategies for enrichment of inorganic species in environmental and biological samples using mostly ICP-MS detectors. In the second part we focus on organic analytes, discussing the role of surface area of the polymer monoliths and density of adsorption sites for specific interactions, including incorporation of nanoparticles, metal organic frameworks, as well as the preparation of hybrid organic-silica monoliths to increase the surface area. Incorporation of ionic liquids to increase the number of types of interaction mechanisms available for retention is also discussed. Monoliths affording molecular recognition properties achieved by including boronate moieties for cis-diol recognition, as well as antibodies and aptamers for specific molecular recognition are also reviewed. The largest number of applications of molecular recognition mechanisms was observed for molecularly imprinted polymer monoliths as a consequence of the simplicity of this approach when compared to the use of immunosorbents or aptamers. The final part examines the on-line applications of immobilized enzyme reactors used for protein digestion in proteomic analysis and for kinetic studies in drug discovery and clinical assays usually coupling the reactors to mass spectrometers.

  18. Human comment dynamics in on-line social systems

    NASA Astrophysics Data System (ADS)

    Wu, Ye; Zhou, Changsong; Chen, Maoying; Xiao, Jinghua; Kurths, Jürgen

    2010-12-01

    Human comment is studied using data from ‘tianya’ which is one of the most popular on-line social systems in China. We found that the time interval between two consecutive comments on the same topic, called inter-event time, follows a power-law distribution. This result shows that there is no characteristic decay time on a topic. It allows for very long periods without comments that separate bursts of intensive comments. Furthermore, the frequency of a different ID commenting on a topic also follows a power-law distribution. It indicates that there are some “hubs” in the topic who lead the direction of the public opinion. Based on the personal comments habit, a model is introduced to explain these phenomena. The numerical simulations of the model fit well with the empirical results. Our findings are helpful for discovering regular patterns of human behavior in on-line society and the evolution of the public opinion on the virtual as well as real society.

  19. FEDIX on-line information service: Design, develop, test, and implement, an on-line research and education information service

    SciTech Connect

    Rodman, J.A.

    1992-01-01

    The FEDIX Annual Status Report provides details regarding an on-line information project designed, developed and implemented by Federal Information Exchange, Inc., a diversified information services company. This document details the project design activities, summarizes the developmental phases of the project and describes the implementation activities generated to fulfill the project's objectives. The information contained in this document illustrates FIE's continuing commitment to serve as the link that facilitates the dissemination of federal information to the education community. This report reviews the project accomplishments and describes intended service enhancements.

  20. Electroplating of nanostructured polyaniline-polypyrrole composite coating in a stainless-steel tube for on-line in-tube solid phase microextraction.

    PubMed

    Asiabi, Hamid; Yamini, Yadollah; Seidi, Shahram; Esrafili, Ali; Rezaei, Fatemeh

    2015-06-05

    In this work, a novel and efficient on-line in-tube solid phase microextraction method followed by high performance liquid chromatography was developed for preconcentration and determination of trace amounts of parabens. A nanostructured polyaniline-polypyrrole composite was electrochemically deposited on the inner surface of a stainless steel tube and used as the extraction phase. Several important factors that influence the extraction efficiency, including type of solid-phase coating, extraction and desorption times, flow rates of the sample solution and eluent, pH, and ionic strength of the sample solution were investigated and optimized. Under the optimal conditions, the limits of detection were in the range of 0.02-0.04 μg L(-1). This method showed good linearity for parabens in the range of 0.07-50 μg L(-1), with coefficients of determination better than 0.998. The intra- and inter-assay precisions (RSD%, n=3) were in the range of 5.9-7.0% and 4.4-5.7% at three concentration levels of 2, 10, and 20 μg L(-1), respectively. The extraction recovery values for the spiked samples were in the acceptable range of 80.3-90.2%. The validated method was successfully applied for analysis of methyl-, ethyl-, and propyl parabens in some water, milk, and juice samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Automated determination of total captopril in urine by liquid chromatography with post-column derivatization coupled to on-line solid phase extraction in a sequential injection manifold.

    PubMed

    Karakosta, Theano D; Tzanavaras, Paraskevas D; Themelis, Demetrius G

    2012-01-15

    The present study reports a new liquid chromatographic (HPLC) method for the determination of the anti-hypertension drug captopril (CAP) in human urine. After its separation from the sample matrix in a reversed phase HPLC column, CAP reacts with the thiol-selective reagent ethyl-propiolate (EP) in a post-column configuration and the formed thioacrylate derivative is detected at 285 nm. Automated 4-fold preconcentration of the analyte prior to analysis was achieved by an on-line solid phase extraction (SPE) step using a sequential injection (SI) manifold. The Oasis HLB SPE cartridges offered quantitative recoveries and effective sample cleaning by applying a simple SPE protocol. The limits of detection and quantitation were 10 μg L(-1) and 35 μg L(-1) respectively. The percent recoveries for the analysis of human urine samples ranged between 90 and 96% and 95 and 104% using aqueous and matrix matched calibration curves respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. On-line coupling of ionic liquid-based single-drop microextraction with capillary electrophoresis for sensitive detection of phenols.

    PubMed

    Wang, Qing; Qiu, Hongdeng; Li, Jing; Liu, Xia; Jiang, Shengxiang

    2010-08-13

    An ionic liquid-based single-drop microextraction (IL-SDME) procedure using IL as an extractant on-line coupled to capillary electrophoresis (CE) is proposed. The method is capable of quantifying trace amounts of phenols in environmental water samples. For the SDME of three phenols, a 2.40 nL IL microdrop was exposed for 10 min to the aqueous sample and then was directly injected into the capillary column for analysis. Extraction parameters such as the extraction time, the IL single-drop volume, pH of the sample solution, ionic strength, volume of the sample solution and the extraction temperature were systematically investigated. Detection limits to three phenols were less than 0.05 microg mL(-1), and their calibration curves were all linear (R(2) > or = 0.9994) in the range from 0.05 to 50 microg mL(-1). And enrichment factors for three phenols were 156, 107 and 257 without agitation, respectively. This method was then utilized to analyze two real environmental samples from Yellow River and tap water, obtaining satisfactory results. Compared with the usual SDME for CE, IL-SDME-CE is a simple, low-cost, fast and environmentally friendly preconcentration technique.

  3. Direct on-line analysis of neutral analytes by dual sweeping via complexation and organic solvent field enhancement in nonionic MEKC.

    PubMed

    Cao, Jun; Li, Bin; Chang, Yan-Xu; Li, Ping

    2009-04-01

    Conventionally, neutral compounds cannot be separated by nonionic micelle capillary electrophoresis. In this report, the development of a novel on-line preconcentration technique combining dual sweeping based on complexation and organic solvent field enhancement is applied to the sensitive and selective analysis of three neutral glucosides: ginsenoside Rf, ginsenoside Rg1, and ginsenoside Re. Nonionic micelle detectability by CE is demonstrated through effective focusing of large sample volumes (up to 38% capillary length) using a dual sweeping mode. This results in a 50- to 130-fold improvement in the LODs relative to conventional injection method. Neutral compounds sweeping is examined in terms of analyte mobility dependence on borate complexation, solvent viscosity difference, and Brij-35 interaction. Enhanced focusing performance by this hyphenated method was demonstrated by a greater than fourfold reduction in glucoside bandwidth, as compared with common sweeping (devoid of organic solvent-mediated sweeping method in the sample matrices). Moreover, separation efficiencies greater than a million theoretical plates can be achieved by sweeping large sample volumes into narrow zones. The designated method was also tested for its ability to determine the presence of glucosides in the crude extracts obtained from plant sample.

  4. On-line analysis of secondary ozonides from cyclohexene and D-limonene ozonolysis using atmospheric sampling townsend discharge ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Nøjgaard, J. K.; Nørgaard, A. W.; Wolkoff, P.

    An on-line technique has been developed for analysis of gas-phase oxidation products formed in a reaction flow tube using different reaction times, concentrations and humidities. Products of ozonolysis, including thermally labile secondary ozonides (SOZ), were directly introduced into an atmospheric sampling townsend discharge ionization (ASTDI) source coupled to a triple quadrupole mass spectrometer (MS). Instant changes in the product composition were monitored in the total-ion chromatogram, or by fragment ions in the collision activated dissociation mass spectra by use of MS/MS scan techniques. Assignment of the individual ions was accomplished by inspection of the products' mass spectra obtained by pre-concentration of the gas phase on a dedicated short column followed by chromatographic analysis. The observed reaction products correspond to those identified with other techniques. Of relevance for future mechanistic modelling, is the point that conditions of excess D-limonene favoured the formation of the D-limonene SOZ (major product), which was observed to be quite stable in dry and humid air, without oxidants. The D-limonene/ozone ratio was observed to be crucial for the stability of the SOZ, because it is prone to ozonolysis, and no SOZ could be detected in completely reacted 1:1 mixtures.

  5. On-line SPE-UHPLC method using fused core columns for extraction and separation of nine illegal dyes in chilli-containing spices.

    PubMed

    Khalikova, Maria A; Satínský, Dalibor; Smidrkalová, Tereza; Solich, Petr

    2014-12-01

    The presented work describes the development of a simple, fast and effective on-line SPE-UHPLC-UV/vis method using fused core particle columns for extraction, separation and quantitative analysis of the nine illegal dyes, most frequently found in chilli-containing spices. The red dyes Sudan I-IV, Sudan Red 7B, Sudan Red G, Sudan Orange G, Para Red, and Methyl Red were separated and analyzed in less than 9 min without labor-consuming pretreatment procedure. The chromatographic separation was performed on Ascentis Express RP-Amide column with gradient elution using mixture of acetonitrile and water, as a mobile phase at a flow rate of 1.0 mL min(-1) and 55°C of temperature. As SPE sorbent for cleanup and pre-concentration of illegal dyes short guard fused core column Ascentis Express F5 was used. The applicability of proposed method was proven for three different chilli-containing commercial samples. Recoveries for all compounds were between 90% and 108% and relative standard deviation ranged from 1% to 4% for within- and from 2% to 6% for between-day. Limits of detection showed lower values than required by European Union regulations and were in the range of 3.3-10.3 µg L(-1) for standard solutions, 5.6-235.6 µg kg(-1) for chilli-containing spices. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Performance and stability of low-cost dye-sensitized solar cell based crude and pre-concentrated anthocyanins: Combined experimental and DFT/TDDFT study

    NASA Astrophysics Data System (ADS)

    Chaiamornnugool, Phrompak; Tontapha, Sarawut; Phatchana, Ratchanee; Ratchapolthavisin, Nattawat; Kanokmedhakul, Somdej; Sang-aroon, Wichien; Amornkitbamrung, Vittaya

    2017-01-01

    The low cost DSSCs utilized by crude and pre-concentrated anthocyanins extracted from six anthocyanin-rich samples including mangosteen pericarp, roselle, red cabbage, Thai berry, black rice and blue pea were fabricated. Their photo-to-current conversion efficiencies and stability were examined. Pre-concentrated extracts were obtained by solid phase extraction (SPE) using C18 cartridge. The results obviously showed that all pre-concentrated extracts performed on photovoltaic performances in DSSCs better than crude extracts except for mangosteen pericarp. The DSSC sensitized by pre-concentrated anthocyanin from roselle and red cabbage showed maximum current efficiency η = 0.71% while DSSC sensitized by crude anthocyanin from mangosteen pericarp reached maximum efficiency η = 0.97%. In addition, pre-concentrated extract based cells possess more stability than those of crude extract based cells. This indicates that pre-concentration of anthocyanin via SPE method is very effective for DSSCs based on good photovoltaic performance and stability. The DFT/TDDFT calculations of electronic and photoelectrochemical properties of the major anthocyanins found in the samples are employed to support the experimental results.

  7. Determination of caffeine as a tracer of sewage effluent in natural waters by on-line solid-phase extraction and liquid chromatography with diode-array detection.

    PubMed

    Chen, Zuliang; Pavelic, Paul; Dillon, Peter; Naidu, Ravenda

    2002-11-01

    A new liquid chromatographic (LC) method with automated on-line solid phase extraction was developed to determine caffeine at sub-microgram per litre concentrations in waters. The filtered sample was pre-concentrated in a pre-column, which was backwashed with acidic water at pH of 2.70. The concentrated caffeine was separated using a C18 column with a gradient of water-acetonitrile and detected by diode array detection (DAD) at 210 nm. Four different pre-columns: C18, PRP-1, PLRP-s and Env were evaluated for the on-line solid phase extraction of caffeine. The PLRP-s pre-column allowed the enrichment of up to 100 mL of environmental water sample with highest recovery. The procedure was validated by recovery experiments in water spiked at 0.5 1.0 and 4.0 microg/L. Average recoveries were between 92.1 +/- 5.2% and 97.8 +/- 2.6%. Detection limits as low as 0.1 microg/L from 50 ml of sample were achieved. The proposed method has the advantages of higher reliability and sensitivity, simpler sample preparation and shorter analysis time in comparison with off-line solid-phase extraction. The utility of the method was demonstrated at two field sites: Bolivar and Halls Head (Australia). At Bolivar, the treatment process included 6-week lagoon storage which is believed to have attenuated caffeine, and thus limited its use as an environmental tracer of reclaimed water. At the Halls Head site, where the storage period is shorter, caffeine was detected in both the treated sewage effluent and in groundwater near ponds where the reclaimed water is at similar concentrations. These results suggest that the environmental conditions under which caffeine is conservative require better definition.

  8. Miniaturized preconcentration methods based on liquid-liquid extraction and their application in inorganic ultratrace analysis and speciation: A review

    NASA Astrophysics Data System (ADS)

    Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2009-01-01

    Liquid-liquid extraction (LLE) is widely used as a pre-treatment technique for separation and preconcentration of both organic and inorganic analytes from aqueous samples. Nevertheless, it has several drawbacks, such as emulsion formation or the use of large volumes of solvents, which makes LLE expensive and labour intensive. Therefore, miniaturization of conventional liquid-liquid extraction is needed. The search for alternatives to the conventional LLE using negligible volumes of extractant and the minimum number of steps has driven the development of three new miniaturized methodologies, i.e. single-drop microextraction (SDME), hollow fibre liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME). The aim of this paper is to provide an overview of these novel preconcentration approaches and their potential use in analytical labs involved in inorganic (ultra)trace analysis and speciation. Relevant applications to the determination of metal ions, metalloids, organometals and non-metals are included.

  9. A comprehensive study of methyl and ethylmercury determination in natural water by adsorbent preconcentration an GC/AFS analysis

    SciTech Connect

    Cai, Y.; Jaffe, R.; Jones, R.

    1996-10-01

    This paper presents a sample preparation method for the determination of MeHg and ethylmercury (EtHg) in water samples by adsorbent preconcentration and capillary gas chromatography/atomic fluorescence detection (GC/AFS). MeHg and EtHg were preconcentrated from water on to a screening column packed with sulfhydryl cotton fiber (SCF) adsorbent. The MeHg and EtHg were elated by a mixture of acidic potassium bromide and copper sulfate solution, and then extracted using dichloromethane. Breakthrough volume of the SCF column used was tested using high organic matter-containing water from the Florida Everglades and seawater from Florida Bay. Good recoveries were achieved for both MeHg (85%) and EtHg (70%), and no breakthrough was found up to 2 L of sample. The detection limit was 0.01 ng/L in a 2 L water sample for both MeHg and EtHg.

  10. A compact ammonia detector with sub-ppb accuracy using near-infrared photoacoustic spectroscopy and preconcentration sampling.

    PubMed

    Pogány, Andrea; Mohácsi, Arpád; Varga, Attila; Bozóki, Zoltán; Galbács, Zoltán; Horváth, László; Szabó, Gábor

    2009-02-01

    This paper describes the first successful application of a preconcentration unitto increase the sensitivity of a photoacoustic ammonia concentration measuring instrument. A diode laser based near-infrared (1532 nm) photoacoustic ammonia monitoring instrument was combined with a tungsten (VI) oxide coated preconcentration unit to reach a sub-ppb detection limit with a compact, automatic measuring instrument. The system has no measurable cross-sensitivity to common atmospheric gases, most importantly to water vapor and carbon dioxide. The minimum detectable amount of ammonia is 2.9 ng, which means a minimum detectable concentration of 0.5 ppb with a 30-min measurementtime. Results of intercomparison measurements carried out both under laboratory and field conditions with reference to an electrochemical AMANDA instrument prove the applicability of the system in environmental ammonia concentration monitoring.

  11. Simultaneous preconcentration of cadmium and lead in water samples with silica gel and determination by flame atomic absorption spectrometry.

    PubMed

    Xu, Hongbo; Wu, Yun; Wang, Jian; Shang, Xuewei; Jiang, Xiaojun

    2013-12-01

    A new method that utilizes pretreated silica gel as an adsorbent has been developed for simultaneous preconcentration of trace Cd(II) and Pb(II) prior to the measurement by flame atomic absorption spectrometry. The effects of pH, the shaking time, the elution condition and the coexisting ions on the separation/preconcentration conditions of analytes were investigated. Under optimized conditions, the static adsorption capacity of Cd(II) and Pb(II) were 45.5 and 27.1mg/g, the relative standard deviations were 3.2% and 1.7% (for n = 11), and the limits of detection obtained were 4.25 and 0.60 ng/mL, respectively. The method was validated by analyzing the certified reference materials GBW 07304a (stream sediment) and successfully applied to the analysis of various treated wastewater samples with satisfactory results.

  12. Development of an on-line bioterrorism preparedness course.

    PubMed

    Westphal, Robert G; Jewell, Susan; Skawinski, Edward

    2005-11-01

    To reach a large audience of public health workers and others interested in learning more about bioterrorism and emergency preparedness, an on-line, Web-based, certificated course entitled "Terrorism, Preparedness and Public Health: An Introduction" was planned, developed, and implemented. Interactivity and other user-friendly devices helped it gain acceptance. To date (May 2005), more than 6,000 people from all 50 states and some foreign countries have registered for the course, and about 2,400 have passed an exam for a certificate of completion. We believe the success of this course is related to the strength and accuracy of the content and its historical perspective; to the quality of the technical development, including multiple levels of interactivity, ease of use, and a printed completion certificate; and to the use of real case studies and the lack of dramatic overstatement.

  13. On-line single particle analysis of environmental tobacco smoke

    SciTech Connect

    Prather, K.A.; Morrical, B.O.

    1995-12-01

    Environmental Tobacco Smoke (ETS) is a major component in indoor and outdoor air pollution. It has been estimated that ETS accounts for approximately 2.7% of fine organic aerosol emissions in the Los Angeles area and the adverse health effects of cigarette emissions have been well documented. Particulate analysis by conventional analytical methods, such as GC/MS, do not provide information on individual aerosol particles due to the off-line collection and sampling procedures. Aerosol Time-Flight Mass Spectrometry is an on-line analytical technique that is uniquely capable of single particle analysis, simultaneously providing information on particle size and chemical composition. It will be demonstrated that this technique can be used to show how the chemical composition of ETS particles changes as a function of size. Data demonstrating the ability to monitor chemical composition and size change as a function of time will also be presented.

  14. Enabling the On-line Intrinsic Evolution of Analog Controllers

    NASA Technical Reports Server (NTRS)

    Gwaltney, David A.; Ferguson, Michael I.

    2005-01-01

    The intrinsic evolution of analog controllers to provide closed-loop control of the speed of a DC motor has been previously demonstrated at NASA Marshall Space Flight Center. A side effect of the evolutionary process is that during evolution there are necessarily poor configurations to be evaluated that could cause damage to the plant, This paper concerns the development and implementation of a safe Evolvable Analog Controller (EAC) architecture able to evolve controllers on-line even in the presence of these poor configurations, The EAC concept is discussed and experimental results are presented that show the feasibility of the approach This EAC architecture represents the first in a series of steps required to make deployment of an evolvable controller a reality.

  15. Enabling the On-Line Intrinsic Evolution of Analog Controllers

    NASA Technical Reports Server (NTRS)

    Gwaltney, David A.; Ferguson, Michael I.

    2005-01-01

    The intrinsic evolution of analog controllers to provide closed-loop control of the speed of a DC motor has been previously demonstrated at NASA Marshall Space Flight Center. A side fleet of the evolutionary process is that during evolution there are necessarily poor configurations to be evaluated that could cause damage to the plant. This paper concern the development and implementation of a safe Evolvable Analog Controller (EAC) architecture able to evolve controllers on-line even in the presence of these poor configurations. The EAC concept is discussed and experimental results are presented that show the feasibility of the approach This EAC architecture represents the first in a series of steps required to make deployment of an evolvable controller a reality.

  16. Holographic digital microscopy in on-line process control

    NASA Astrophysics Data System (ADS)

    Osanlou, Ardeshir

    2011-09-01

    This article investigates the feasibility of real-time three-dimensional imaging of microscopic objects within various emulsions while being produced in specialized production vessels. The study is particularly relevant to on-line process monitoring and control in chemical, pharmaceutical, food, cleaning, and personal hygiene industries. Such processes are often dynamic and the materials cannot be measured once removed from the production vessel. The technique reported here is applicable to three-dimensional characterization analyses on stirred fluids in small reaction vessels. Relatively expensive pulsed lasers have been avoided through the careful control of the speed of the moving fluid in relation to the speed of the camera exposure and the wavelength of the continuous wave laser used. The ultimate aim of the project is to introduce a fully robust and compact digital holographic microscope as a process control tool in a full size specialized production vessel.

  17. An on-line method in studying music parsing.

    PubMed

    Berent, I; Perfetti, C A

    1993-03-01

    Listening to music entails the construction of a mental representation based on partial and ambiguous information. This study examines an experimental method that reflects such parsing decisions on-line by detecting the cognitive load resulting from temporary parsing failures. The method investigated was a divided attention paradigm in which listening to music was the primary task and click detection was a concurrent secondary task. It was hypothesized that increasing the complexity of the primary task by introducing an unprepared chromatic modulation results in an increase in response latencies to a click presented immediately after the modulatory shift. The support of this prediction by musicians' data provides evidence for the sensitivity of the paradigm. The failure of non-musicians to reflect the expected load is attributed to their attention-allocation strategy. These results are discussed in terms of their implications on the view of the musical parser as deterministic.

  18. On-Line Safe Flight Envelope Determination for Impaired Aircraft

    NASA Technical Reports Server (NTRS)

    Lombaerts, Thomas; Schuet, Stefan; Acosta, Diana; Kaneshige, John

    2015-01-01

    The design and simulation of an on-line algorithm which estimates the safe maneuvering envelope of aircraft is discussed in this paper. The trim envelope is estimated using probabilistic methods and efficient high-fidelity model based computations of attainable equilibrium sets. From this trim envelope, a robust reachability analysis provides the maneuverability limitations of the aircraft through an optimal control formulation. Both envelope limits are presented to the flight crew on the primary flight display. In the results section, scenarios are considered where this adaptive algorithm is capable of computing online changes to the maneuvering envelope due to impairment. Furthermore, corresponding updates to display features on the primary flight display are provided to potentially inform the flight crew of safety critical envelope alterations caused by the impairment.

  19. An expert system to perform on-line controller tuning

    NASA Technical Reports Server (NTRS)

    Litt, Jonathan S.

    1990-01-01

    An expert system which tunes a Proportional-Integral-Derivative (PID) controller on-line for a single-input-single-output multiple-lag process with dead time is described. The expert system examines features of the previous transient responses and their corresponding sets of controller parameters. It determines a new set of controller gains to obtain a more desirable time response. This technique can be used to determine and implement a different set of PID gains for each operating regime and, once in steady state, the system can be used to find optimal parameters for load disturbance rejection. The expert system can be applied to any system of the specified form (aerospace, industrial, etc.) and can be expanded to include additional process models.

  20. A versatile apparatus for on-line emission channeling experiments

    SciTech Connect

    Silva, M. R.; Wahl, U.; Correia, J. G.

    2013-07-15

    The concept and functionality of an apparatus dedicated to emission channeling experiments using short-lived isotopes on-line at ISOLDE/CERN is described. The setup is assembled in two functional blocks – (a) base stand including beam collimation, implantation and measurement chamber, cryogenic extension, and vacuum control system and (b) Panmure goniometer extension including maneuvering cradle and sample heating furnace. This setup allows for in situ implantation and sample analysis in the as-implanted state and upon cooling down to 50 K and during annealing up to 1200 K. The functionality of the setup will be illustrated with the example of establishing the lattice location of {sup 56}Mn probes implanted into GaAs.

  1. A versatile apparatus for on-line emission channeling experiments.

    PubMed

    Silva, M R; Wahl, U; Correia, J G; Amorim, L M; Pereira, L M C

    2013-07-01

    The concept and functionality of an apparatus dedicated to emission channeling experiments using short-lived isotopes on-line at ISOLDE∕CERN is described. The setup is assembled in two functional blocks - (a) base stand including beam collimation, implantation and measurement chamber, cryogenic extension, and vacuum control system and (b) Panmure goniometer extension including maneuvering cradle and sample heating furnace. This setup allows for in situ implantation and sample analysis in the as-implanted state and upon cooling down to 50 K and during annealing up to 1200 K. The functionality of the setup will be illustrated with the example of establishing the lattice location of (56)Mn probes implanted into GaAs.

  2. On-Line Prompt Gamma Neutron Activation Analyzers

    SciTech Connect

    R. J. Proctor; M. J. Hurwitz

    2000-06-04

    Prompt gamma neutron activation analysis (PGNAA) has become an important method for performing elemental analysis for on-line process control. A major advantage of PGNAA is that neutrons are a very penetrating radiation (200 mm), little influenced by the molecular form, temperature, or physical properties of the process materials being measured. The neutrons reacting with the process materials produce the gamma rays 'promptly' (in picoseconds), and the majority of the gamma rays have good penetrability (300 mm). This offers the advantage of very large analysis volumes, and unlike all other analytical methods, PGNAA has the ability to analyze the entire flow of material. PGNAA analyzers deliver rapid, sampling free, elemental analysis on large top-size, bulk materials moving at many metres per second on conveyor belts or in pipes or chutes. This paper describes some applications of PGNAA, the analysis method, sensitivities, and instrumentation.

  3. Detectors for on-line prompt gamma neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Proctor, Ray; Yusuf, Siaka; Miller, Jim; Scott, Clark

    1999-02-01

    The uncertainty of the elemental analysis is one of the major factors governing the utility of on-line prompt gamma neutron activation analysis (PGNAA) in the blending and sorting of bulk materials. In this paper, a method for quantifying the relative uncertainty from full spectrum analysis on complex materials is presented. The method was applied to three different detector types, NaI, HPGe, and BGO. The results show that the 5-10 times higher detection efficiency of a large size scintillation detector can often outweigh the resolution superiority of a HPGe detector for simple to medium complex bulk materials. The better detector resolution of sodium iodide gave a significantly lower analysis uncertainty than BGO for equal efficiency detectors.

  4. Synthetic Gene Design Using Codon Optimization On-Line (COOL).

    PubMed

    Yu, Kai; Ang, Kok Siong; Lee, Dong-Yup

    2017-01-01

    Codon optimization has been widely used for designing native or synthetic genes to enhance their expression in heterologous host organisms. We recently developed Codon Optimization On-Line (COOL) which is a web-based tool to provide multi-objective codon optimization functionality for synthetic gene design. COOL provides a simple and flexible interface for customizing codon optimization based on several design parameters such as individual codon usage, codon pairing, and codon adaptation index. User-defined sequences can also be compared against the COOL optimized ones to show the extent by which the user's sequences can be evaluated and further improved. The utility of COOL is demonstrated via a case study where the codon optimized sequence of an invertase enzyme is generated for the enhanced expression in E. coli.

  5. On-Line Robust Modal Stability Prediction using Wavelet Processing

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J.; Lind, Rick

    1998-01-01

    Wavelet analysis for filtering and system identification has been used to improve the estimation of aeroservoelastic stability margins. The conservatism of the robust stability margins is reduced with parametric and nonparametric time- frequency analysis of flight data in the model validation process. Nonparametric wavelet processing of data is used to reduce the effects of external disturbances and unmodeled dynamics. Parametric estimates of modal stability are also extracted using the wavelet transform. Computation of robust stability margins for stability boundary prediction depends on uncertainty descriptions derived from the data for model validation. The F-18 High Alpha Research Vehicle aeroservoelastic flight test data demonstrates improved robust stability prediction by extension of the stability boundary beyond the flight regime. Guidelines and computation times are presented to show the efficiency and practical aspects of these procedures for on-line implementation. Feasibility of the method is shown for processing flight data from time- varying nonstationary test points.

  6. Issues for Bringing Electron Beam Irradiators On-Line

    SciTech Connect

    Kaye, R.J.; Turman, B.N.

    1999-04-20

    Irradiation of red meat and poultry has been approved by the U.S. FDA, and the U.S. Department of Agriculture's rule for processing red meat is out for comment. Looking beyond the current issues of packaging materials, labeling, and consumer acceptance, this paper reviews the next step of implementation and how to remove, or at least reduce, the barriers to utilization. Polls of the user community identified their requirements for electron beam or x-ray processing of meat or poultry and their concerns about implementation for on-line processing. These needs and issues are compared to the capabilities of the accelerator industry. The critical issues of beam utilization and dose uniformity, factors affecting floor space requirements, and treatment costs are examined.

  7. On-line control of the nonlinear dynamics for synchrotrons

    NASA Astrophysics Data System (ADS)

    Bengtsson, J.; Martin, I. P. S.; Rowland, J. H.; Bartolini, R.

    2015-07-01

    We propose a simple approach to the on-line control of the nonlinear dynamics in storage rings, based on compensation of the nonlinear resonance driving terms using beam losses as the main indicator of the strength of a resonance. The correction scheme is built on the analysis of the resonance driving terms in first perturbative order and on the possibility of using independent power supplies in the sextupole magnets, which is nowadays present in many synchrotron light sources. Such freedom allows the definition of "smart sextupole knobs" attacking each resonance separately. The compensation scheme has been tested at the Diamond light source and proved to be effective in opening up the betatron tune space, resonance free, available to the electron beam and to improve the beam lifetime.

  8. WMI2, the student's on-line symbolic calculator

    NASA Astrophysics Data System (ADS)

    Kovács, Zoltán

    2011-06-01

    Student activities focused on discovering mathematics play an important role in the teaching and learning process. WebMathematics Interactive (WMI2) was developed to offer a fast and user-friendly on-line web interface to enhance the quality of both theoretical and applied mathematics courses. For the teacher, in the classroom, it provides immediate numerical computations, algebraic manipulations and graphical representations. For our students, WMI2 provides a unique classroom experience in their own Hungarian language that generates various mathematical representations. At home our students have a support system to help them explore mathematical concepts, test their mathematical knowledge and to assist them in their problem solving. WMI2 has been under continuous development since 2002 and has been in classroom use since 2007. It is freely available in 10 languages.

  9. Bamberg Observatory Plate Surveys: Digitization and On-Line Access

    NASA Astrophysics Data System (ADS)

    Tsvetkov, Milcho; Heber, Ulrich; Tsvetkova, Katya; Borisova, Ana; Kalaglarsky, Damyan; Bogdanovski, Rumen; Drechsel, Horst; Wilms, Joern

    2007-08-01

    The results from five-year work on the Bamberg Observatory plate collection from inventory to digitization are presented. The project supported by the Alexander von Humboldt Foundation, Deutsche Forschung Gemeinschaft, and Bulgarian Academy of Sciences has begun since 2002. At present the information for about 28 000 plates from the Bamberg Southern and Northern surveys is accessible on-line from WFPDB (http://www.skyarchive.org). More than 700 plates are digitized with the professional flatbed scanner EPSON 1640XL. Two more tasks complete the overall project: digitization of the entire plate collection, started with some pilot fields as LMC/SMC, the Pleiades, etc. and linking the digitized information to German Astronomical Virtual Observatory (GAVO) and European Virtual Observatory. Some successful examples of using the Bamberg plate collection to study long-term variability of chromospherically active stars are present.

  10. Preconcentration of pentachlorophenol from sawdust using quinolin-8-ol immobilized on controlled-pore glass and determination by liquid chromatography.

    PubMed

    León-González, M E; Pérez-Arribas, L V; Polo-Díez, L M; Silva-Vargas, M E

    2000-05-01

    A method for quantitative evaluation of pentachlorophenol (PCP) in sawdust has been developed. Pentachlorophenol is extracted from the solid matrix with 0.5 M sodium hydroxide and preconcentration was carried out using quinolin-8-ol immobilized on controlled pore glass. Determination was carried out by using liquid chromatography with detection at 240 nm. Recoveries were between 84 and 97% at 1-3 microg/g.

  11. Liquid electrode plasma-optical emission spectrometry combined with solid-phase preconcentration for on-site analysis of lead.

    PubMed

    Barua, Suman; Rahman, Ismail M M; Alam, Iftakharul; Miyaguchi, Maho; Sawai, Hikaru; Maki, Teruya; Hasegawa, Hiroshi

    2017-08-15

    A relatively rapid and precise method is presented for the determination of lead in aqueous matrix. The method consists of analyte quantitation using the liquid electrode plasma-optical emission spectrometry (LEP-OES) coupled with selective separation/preconcentration by solid-phase extraction (SPE). The impact of operating variables on the retention of lead in SPEs such as pH, flow rate of the sample solution; type, volume, flow rate of the eluent; and matrix effects were investigated. Selective SPE-separation/preconcentration minimized the interfering effect due to manganese in solution and limitations in lead-detection in low-concentration samples by LEP-OES. The LEP-OES operating parameters such as the electrical conductivity of sample solution; applied voltage; on-time, off-time, pulse count for applied voltage; number of measurements; and matrix effects have also been optimized to obtain a distinct peak for the lead at λmax=405.8nm. The limit of detection (3σ) and the limit of quantification (10σ) for lead determination using the technique were found as 1.9 and 6.5ng mL(-1), respectively. The precision, as relative standard deviation, was lower than 5% at 0.1μg mL(-1) Pb, and the preconcentration factor was found to be 187. The proposed method was applied to the analysis of lead contents in the natural aqueous matrix (recovery rate:>95%). The method accuracy was verified using certified reference material of wastewaters: SPS-WW1 and ERM-CA713. The results from LEP-OES were in good agreement with inductively coupled plasma optical emission spectrometry measurements of the same samples. The application of the method is rapid (≤5min, without preconcentration) with a reliable detection limit at trace levels. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Nanofluidic Pre-Concentration Devices for Enhancing the Detection Sensitivity and Selectivity of Biomarkers for Human Performance Monitoring

    DTIC Science & Technology

    2012-12-01

    IgG versus anti-IgG) using fluorescence imaging. For the antibody immobilization process, the chips were etched for microfluidic channels structures... membranes such as Nafion, have been the most commonly adopted.4a−h Other methods based on conductivity gradient,4j temperature gradient,4k−m and pat- terned...constriction edge), as in Fig. 1C, to track formation of the depletion and preconcentration zones. To optimize the electrokinetic force balance for

  13. Flow injection online spectrophotometric determination of uranium after preconcentration on XAD-4 resin impregnated with nalidixic acid.

    PubMed

    Shahida, Shabnam; Ali, Akbar; Khan, Muhammad Haleem; Saeed, Muhammad Mufazzal

    2013-02-01

    In this work, spectrophotometer was used as a detector for the determination of uranium from water, biological, and ore samples with a flow injection system coupled with solid phase extraction. In order to promote the online preconcentration of uranium, a minicolumn packed with XAD-4 resin impregnated with nalidixic acid was utilized. The system operation was based on U(VI) ion retention at pH 6 in the minicolumn at flow rate of 15.2 mL min(-1). The uranium complex was removed from the resin by 0.1 mol dm(-3) HCl at flow rate of 3.2 mL min(-1) and was mixed with arsenazo III solution (0.05 % solution in 0.1 mol dm(-3) HCl, 3.2 mL min(-1)) and driven to flow through cell of spectrophotometer where its absorbance was measured at 651 nm. The influence of chemical (pH and HCl (as eluent and reagent medium) concentration) and flow (sample and eluent flow rate and preconcentration time) parameters that could affect the performance of the system as well as the possible interferents was investigated. At the optimum conditions for 60 s preconcentration time (15.2 mL of sample volume), the method presented a detection limit of 1.1 μg L(-1), a relative standard deviation (RSD) of 0.8 % at 100 μg L(-1), enrichment factor of 30, and a sample throughput of 42 h(-1), whereas for 300 s of the preconcentration time (76 mL of sample volume), a detection limit of 0.22 μg L(-1), a RSD of 1.32 % at 10 μg L(-1), enrichment factor of 150, and a sampling frequency of 11 h(-1) were reported.

  14. Toward the use of surface modified activated carbon in speciation: selective preconcentration of selenite and selenate in environmental waters.

    PubMed

    Tsoi, Yeuk-Ki; Leung, Kelvin Sze-Yin

    2011-04-22

    This paper describes a novel application of tetrabutylammonium hydroxide-modified activated carbon (AC-TBAH) to the speciation of ultra-trace Se(IV) and Se(VI) using LC-ICP-DRC-MS. The anion exchange functionality was immobilized onto the AC surface enables selective preconcentration of inorganic Se anions in a wide range of working pHs. Simultaneous retention and elution of both analytes, followed by subsequent analysis with LC-ICP-DRC-MS, allows to accomplish speciation analysis in natural samples without complicated redox pre-treatment. The laboratory-made column of immobilized AC (0.4 g of sorbent packed in a 6 mL syringe barrel) has achieved analyte enrichment factors of 76 and 93, respectively, for Se(IV) and Se(VI), thus proving its superior preconcentration efficiency and selectivity over common AC. The considerable enhancement in sensitivity achieved by using the preconcentration column has improved the method's detection limits to 1.9-2.2 ng L(-1), which is a 100-fold improvement compared with direct injection. The analyte recoveries from heavily polluted river matrix were between 95.3 and 107.7% with less than 5.0% RSD. The robustness of the preconcentration and speciation method was validated by analysis of natural waters collected from rivers and reservoirs in Hong Kong. The modified AC material is hence presented as a low-cost yet robust substitute for conventional anion exchange resins for routine applications. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Determination of platinum and palladium in geological materials by neutron-activation analysis after fire-assay preconcentration

    USGS Publications Warehouse

    Rowe, J.J.; Simon, F.O.

    1971-01-01

    Fire-asay preconcentration followed by neutron-activation analysis permits the determination of as little as 0.5 ppM of platinum and 0.5 ppM of palladium on a 20-g sample. Platinum and palladium are separated with carriers and beta-counted. Results for the platinum and palladium content of seven U.S.G.S. standard rocks are presented. ?? 1971.

  16. The determination of ozone precursors with a built-in preconcentrator and capillary GC/dual FID

    SciTech Connect

    Kirshen, N.; Coe, D.

    1994-12-31

    Title 1 of the Clean Air Act Amendments of 1990 requires cities or air quality districts that are non-compliant with the Ozone National Ambient Air Quality Standard of 120 ppbv to make continuous measurements of targeted ozone precursors. Air samples must be obtained on a one to three hour basis with the requirement that a high percentage of the time interval will be spent in the sample collection process. The preconcentration of the target analytes from these samples by absorbent trapping rather than the traditional use of cryogenic preconcentration on glass beads with liquid nitrogen has been utilized over the past few years for this application. An Ozone Precursor GC system has been configured with a new built-in sample preconcentration trap (SPT) and associated valving capable of preconcentrating a 200 mL air sample. The sample which may be drawn either from a canister or directly from the ambient air first passes through a stripper column for moisture removal and then through an adsorbent trap. The adsorbent trap is cooled to initial conditions with a very small amount of liquid carbon dioxide providing many runs from one cylinder. Following trapping, the precursors are quickly desorbed with the fast heating (40 C/sec) SPT to parallel columns of Alumina Plot and DB-1 for chromatographic separation and quantitation of the trapped analytes. Dual FIDs provide detection. Optimization of the trapping and chromatographic parameters has been performed using a 60 component EPA precursor standard. The results of these studies and a description of the integrated system will be presented.

  17. Validation of adsorbents for sample preconcentration in compound-specific isotope analysis of common vapor intrusion pollutants.

    PubMed

    Klisch, Monika; Kuder, Tomasz; Philp, R Paul; McHugh, Thomas E

    2012-12-28

    Isotope ratios of volatile organic compounds (VOCs) in the environment are often of interest in contaminant fate studies. Adsorbent preconcentration-thermal desorption of VOCs can be used to collect environmental vapor samples for compound-specific isotope analysis (CSIA). While active adsorbent samplers offer logistic benefits in handling large volumes of air, their performance in preserving VOCs isotope ratios was not previously tested under sampling conditions corresponding to typical indoor air sampling conditions. In this study, the performance of selected adsorbents was tested for preconcentration of TCE (for determination of C and Cl isotope ratios), PCE (C and Cl) and benzene (C and H). The key objective of the study was to identify the adsorbent(s) permitting preconcentration of the target VOCs present in air at low μg/m(3) concentrations, without significant alteration of their isotope ratios. Carboxen 1016 was found to perform well for the full range of tested parameters. Carboxen 1016 can be recommended for sampling of TCE, PCE and benzene, for CSIA, from air volumes up to 100 L. Variable extent of isotope ratio alteration was observed in the preconcentration of the target VOCs on Carbopack B and Carbopack X, resulting from partial analyte loss via adsorbent bed breakthrough and (possibly) via incomplete desorption. The results from testing the Carbopack B and Carbopack X highlight the need of adsorbent performance validation at conditions fully representative of actual sample collection conditions, and caution against extrapolation of performance data toward more challenging sampling conditions. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. [Monitoring on-line treated water and dialysate quality].

    PubMed

    Sobrino Pérez, P E; Barril Cuadrado, G; del Rey Román, C; Sánchez Tomero, J A

    2008-01-01

    On line-treated water has been designed to obtain ultrapure water. This quality of water is obviously necessary to obtain ultrapure dialysate, although this is not the only condition. To keep the quality of the process, is necessary the continuous monitoring of the water treatment, dialysate and haemodialysis machines. After the installation of a water treatment with these characteristics, we developed a protocol to follow up its quality. The measures included in the protocol were: a) Microbiologic, endotoxin and chemical controls of the water on different stage: before and at the end of the treatment, pre-treatment and network of distribution. The chemical analysis included analytical and colorimetric measures. b) Control of specific mechanical functions of the facilities. c) Microbiologic and endotoxin analysis of the dialysate produced by haemodialysis machines. d) Control and maintenance of haemodialysis machines, according to the technical indications. We analyse the initial five years of water treatment with the aim to evaluate quality parameters and efficiency. We explain the reasons of the modifications introduced in the system. During this period we have not any episodes of global or partial contamination. We refer here some incidents related with the quality of raw water supply before the treatment, but in any case it was necessary neither to stop the water supply or to reduce the water quality. We observed a persistent contamination of one haemodialysis monitor due to the port used to get the samples. On line-treated water is at present the most appropriate system to obtain high quality water for haemodialysis. The process must be continuously monitored through specific protocols developed to evaluate the raw water's characteristics and the treated water.

  19. Dispersive liquid-liquid microextraction combined with online preconcentration MEKC for the determination of some phenoxyacetic acids in drinking water.

    PubMed

    Zhang, Yaohai; Jiao, Bining

    2013-09-01

    A fast and simple technique composed of dispersive liquid-liquid microextraction (DLLME) and online preconcentration MEKC with diode array detection was developed for the determination of four phenoxyacetic acids, 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, 2,6-dichlorophenoxyacetic acid, and 4-chlorophenoxyacetic acid, in drinking water. The four phenoxyacetic acids were separated in reversed-migration MEKC to the baseline. About 145-fold increases in detection sensitivity were observed with online concentration strategy, compared with standard hydrodynamic injection (5 s at 25 mbar pressure). LODs ranged from 0.002 to 0.005 mg/L using only the online preconcentration procedures without any offline concentration of the extract. A DLLME procedure was used in combination with the proposed online preconcentration strategies, which achieved the determination of analytes at limits of quantification ranging from 0.2 to 0.5 μg/kg, which is far lower than the maximum residue limits established by China. The satisfactory recoveries obtained by DLMME spiked at two levels ranged from 67.2 to 99.4% with RSD <15%, making this proposed method suitable for the determination of phenoxyacetic acids in water samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Preconcentration of gold ions from water samples by modified organo-nanoclay sorbent prior to flame atomic absorption spectrometry determination.

    PubMed

    Afzali, Daryoush; Mostafavi, Ali; Mirzaei, Mohammad

    2010-09-15

    In this work, the applicability of modified organo nanoclay as a new and easy prepared solid sorbent for the preconcentration of trace amounts of Au(III) ion from water samples is studied. The organo nanoclay was modified with 5-(4'-dimethylamino benzyliden)-rhodanine and used as a sorbent for separation of Au(III) ions. The sorption of gold ions was quantitative in the pH range of 2.0-6.0. Quantitative desorption occurred with 6.0 mL of 1.0 mol L(-1) Na(2)S(2)O(3). The amount of eluted Au(III) was measured using flame atomic absorption spectrometry. In the initial solution the linear dynamic range was in the range of 0.45 ng mL(-1) to 10.0 microg mL(-1), the detection limit was 0.1 ng mL(-1) and the preconcentration factor was 105. Also, the relative standard deviation was +/-2.3% (n=8 and C=2.0 microg mL(-1)) and the maximum capacity of the sorbent was 3.9 mg of Au(III) per gram of modified organo nanoclay. The influences of the experimental parameters including sample pH, eluent volume and eluent type, sample volume, and interference of some ions on the recoveries of the gold ion were investigated. The proposed method was applied for preconcentration and determination of gold in different samples.