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Sample records for on-line bead-injection preconcentration

  1. Hyphenating multisyringe flow injection lab-on-valve analysis with atomic fluorescence spectrometry for on-line bead injection preconcentration and determination of trace levels of hydride-forming elements in environmental samples.

    PubMed

    Long, Xiangbao; Miró, Manuel; Hansen, Elo Harald; Estela, José Manuel; Cerdà, Víctor

    2006-12-15

    In this work the third generation of flow injection analysis, that is, the so-called micro-lab-on-valve (microLOV) approach, is proposed for the first time for the separation, preconcentration, and monitoring of metalloids as hyphenated with atomic fluorescence spectrometry (AFS). This was made feasible by interfacing the micromachined LOV-module with AFS by a multisyringe flowing stream network for on-line postcolumn derivatization of the eluate aimed at generation of hydride species. The potential of this new hyphenated technique for environmental assays was ascertained via determination of ultratrace level concentrations of total inorganic arsenic in freshwater. Employing quantitative preoxidation of As(III) to As(V) in the samples by means of permanganate, the method involves preconcentration of arsenate at pH 10 on a renewable anion exchanger, namely, Q-Sepharose, packed in a LOV microcolumn. The analyte species is afterward stripped out and concurrently prereduced by a 300 microL eluent plug containing 6 mol L(-)1 HCl and 10% KI. The eluate is downstream merged with a metered volume of sodium tetrahydroborate (0.3% w/v) for generation of arsine, which is subsequently quantified by AFS. The flow system facilitates on-column reduction of the retained arsenic with no need for application of programmable stopped flow. Yet, the high concentration of reductant and extreme pH conditions for elution hinder the sorbent to be reused due to gradual deactivation of the functional moieties, so that maximum benefit can be taken from the application of the bead renewable strategy. The proposed procedure is characterized by a high tolerance to metal species and interfering hydride-forming elements. In fact, ratios of Se(IV) to As < or = 5000 and Sb(V) to As < or = 500 are tolerated at the 10% interference level. Under the optimized experimental conditions, a detection limit (3sigma) of 0.02 ng mL(-1) As, a dynamic linear range of 0.05-2.0 ng mL(-1) As (by tailoring the AFS

  2. 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.

  3. 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

  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.

  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 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

  8. 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)).

  9. 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.

  10. 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.

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. [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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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).

  6. 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%).

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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).

  16. 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.

  17. 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.

  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. 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).

  20. 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.

  1. 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.

  2. 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%.

  3. 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.

  4. 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).

  5. 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)).

  6. 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.

  7. 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.

  8. 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.

  9. Particle preconcentrator

    SciTech Connect

    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.

  10. Particle preconcentrator

    SciTech Connect

    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.

  11. 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.

  12. 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.

  13. 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").

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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…

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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...

  9. 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.

  10. 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.

  11. 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,…

  12. 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.

  13. 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.

  14. 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 ...

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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…

  5. 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.

  6. 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.

  7. 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)

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    DTIC Science & Technology

    2014-11-24

    nano-slit devices and optimized electrokinetic pre-concentration conditions for key neurological biomarkers of interest, by using nanoparticles and...devices and optimized electrokinetic pre-concentration conditions for key neurological biomarkers of interest, by using nanoparticles and aptamers to...electrokinetic preconcentration conditions for key neurological biomarkers of interest, by using nanoparticles and aptamers to enhance specificity

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. [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%.

  1. 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.

  2. 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...

  3. 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…

  4. 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.

  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. 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.

  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. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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%.

  2. 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

  3. 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

  4. 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%.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  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 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  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. 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.

  18. 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.

  19. 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…

  20. 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…

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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%).

  9. 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...

  10. 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...

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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 ...

  6. 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.

  7. 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).

  8. 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.

  9. 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.

  10. 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

  11. 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…

  12. 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…

  13. 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…

  14. 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…

  15. 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…

  16. 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…

  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. 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…

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Optimization of Antibody-Conjugated Magnetic Nanoparticles for Target Preconcentration and Immunoassays

    DTIC Science & Technology

    2010-01-01

    developed at the Naval Research Laboratory (NRL),2 which typically performs multiplexed immunoassays , has been used successfully for the detection of a...Bioanal. Chem. 394 (2009) 61–69. [14] D. Tang, B. Su, J. Tang, J. Ren, G. Chen, Nanoparticle-based sandwich electrochemical immunoassay for...Optimization of antibody-conjugated magnetic nanoparticles for target preconcentration and immunoassays Joshua E. Smith a,b,⇑, Kim E. Sapsford c,d,1

  10. 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)

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. An on-line NMR technique with a programmable processor

    SciTech Connect

    Razazian, K.; Dieckman, S.L.; Raptis, A.C.

    1995-07-01

    Nuclear magnetic resonance (NMR) spectroscopy is used to determine molecular content of materials, mainly in laboratory measurements. The reduced cost of fast computer processors, together with recent break throughs in digital signal processor technology, has facilitated the on-line use of NMR by allowing modifications of the available technology. This paper describes a system and an algorithm for improving the on-line operations. It is base on the time-domain NMR signal detected by the controller and some prior knowledge of chemical signal patterns. The desired signal can be separated from a composite signal by using an adaptive line enhancer (ALE) filter. This technique would be useful for upgrading process procedures in on-line manufacturing.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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…

  13. 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…

  14. 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)

  15. 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…

  16. 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.

  17. 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…

  18. 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…

  19. 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

  20. 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)

  1. 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…

  2. 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…

  3. Expanding Capacity With an Accelerated On-Line BSN Program.

    PubMed

    Lindley, Marie Kelly; Ashwill, Regina; Cipher, Daisha J; Mancini, Mary E

    Colleges of nursing are challenged to identify innovative, efficient, and effective mechanisms to expand enrollment in prelicensure programs. This objective of this project was to identify whether a prelicensure nursing program that is both accelerated and on-line is as effective as a traditional face-to-face program, in terms of graduation rates and National Council Licensure Exam pass rates.

  4. 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...

  5. 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.

  6. 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…

  7. 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)

  8. 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…

  9. 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…

  10. 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)

  11. 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…

  12. 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…

  13. 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]…

  14. 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.

  15. 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…

  16. 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…

  17. 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.

  18. 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…

  19. 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 ...

  20. 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…

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. Sorbent flotation in trace metal analysis: Preconcentration of uranium traces on hydrophobized hyphan-cellulose

    SciTech Connect

    Braun, T.; Galsan, V.; Toelgyessy, J.

    1994-01-01

    The use of flotation in analytical chemistry has established itself as a reliable technique for the separation and preconcentration of trace elements. In most of the applications in situ generated inorganic and organic precipitates were used as trace element gatherers and floated to the surface of large volumes of solution with the aid of a rising stream of gas bubbles and well selected collector surfactants. This procedure of {open_quotes}precipitate flotation{close_quotes} has been well studied and applied to many problems of preconcentration chemistry. As far as the present authors are aware of solid preformed sorbents have not yet been separated from large volumes of solution by flotation after batch type sorption of trace elements on them. That is why the authors considered it worthwhile to explore the analytical potentialities of the separation of commercial and non-commercial solid sorbents by flotation. The new procedure the authors like to call {open_quotes}sorbent flotation{close_quotes} refers to the separation of preformed solid sorbents from large volumes of solution and can be viewed as an extension to the already known flotation of in situ formed inorganic and organic precipitates.

  7. 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.

  8. 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

  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. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  15. 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

  16. 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 ).

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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).

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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).

  16. 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.

  17. 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.

  18. 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.

  19. On-line documentation of patient care orders.

    PubMed Central

    Prophet, C. M.

    1995-01-01

    The INFORMM NIS (Information Network For Online Retrieval & Medical Management Nursing Information System) provides on-line documentation of patient care orders. These orders, generated by the nurse or the physician, prescribe direct patient care and do not include interdepartmental orders such as laboratory, radiology, or pharmacy. The order charting functions support charting efficiency by defaulting previous responses so that the user enters only updates to earlier findings or new data. Available in tables maintained by NIS staff, charting responses provide decision support by suggesting valid results for each order. Using point-of-care devices, nursing staff chart patient data that are immediately available for review by all authorized members of the health care team. These data are printed automatically on computer-generated chart forms every twenty-four hours, but may be printed also on demand. Additionally, the patient data report, containing patient data entered on-line in the sixteen or twenty-four hours immediately preceding the print request, provides a summary that is useful for nurses' report and physicians' rounds. PMID:8563325

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Effective determination of ampicillin in cow milk using a molecularly imprinted polymer as sorbent for sample preconcentration.

    PubMed

    Soledad-Rodríguez, B; Fernández-Hernando, P; Garcinuño-Martínez, R M; Durand-Alegría, J S

    2017-06-01

    The aim of this study was to prepare molecularly imprinted polymers (MIPs) with ampicillin (AMP) and to evaluate the feasibility of these materials for being used as solid phase extraction sorbent for the selective preconcentration and determination of AMP in cow milk samples. MIPs were synthesized by bulk polymerization using methacrylic acid or methyl methacrylate as monomer and ethylene glycol dimethacrylate as cross-linker at different ratios. Characterization of the MIPs were carried out by Fourier-transform infrared spectrometry. The variables affecting the molecularly imprinted solid-phase extraction (MISPE) procedure were optimized. AMP recoveries were higher than 98%, and RSD less than 7%. A preconcentration factor of 20 was reached, which was sufficient to determine AMP at levels allowed by the EU (4μgkg(-1)) in cow milk. The selectivity of the AMP-MIP was evaluated in presence of other structurally related β-lactam antibiotics (amoxicillin, oxacillin, penicillin G).

  9. 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.

  10. 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.

  11. State of the art in on-line techniques coupled to flow injection analysis FIA/on-line- a critical review

    PubMed Central

    Puchades, R.; Maquieira, A.; Atienza, J.; Herrero, M. A.

    1990-01-01

    Flow injection analysis (FIA) has emerged as an increasingly used laboratory tool in chemical analysis. Employment of the technique for on-line sample treatment and on-line measurement in chemical process control is a growing trend. This article reviews the recent applications of FlA. Most papers refer to on-line sample treatment. Although FIA is very well suited to continuous on-line process monitoring, few examples have been found in this areamost of them have been applied to water treatment or fermentation processes. PMID:18925271

  12. 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.

  13. 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.

  14. 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.

  15. Application of modified simplex on the development of a preconcentration system for cadmium determination in sediments, food and cigarettes.

    PubMed

    Santos, Queila O; Moreno, Islania; Santos, Leandro Dos; Santos, Aldenor G; Souza, Valdinei S; Bezerra, Marcos A

    2016-05-13

    A modified simplex algorithm was used to optimize a system of preconcentration for cadmium determination in samples of sediments, cigarettes and food using flame atomic absorption spectrometry. The preconcentration system is based on the sorption of cadmium in a minicolumn packed with Amberlite XAD-2 resin functionalized with 3,4-dihydroxybenzoic acid (DHB). The optimized variables were pH and sampling flow rate and the optimum conditions found for these variables were, respectively 8.7 and 8.8 mL min-1. The developed system showed a preconcentration factor of 15.3, detection limit of 0.49 µg L-1, quantification limit of 1.65 µg L-1 and precision expressed as relative standard deviation (% RSD, n=10) of 5.9. The accuracy of the method was checked by analysis of estuary sediment certified reference material (NIST 1646-1). The cadmium concentrations found in sediment samples ranged from 1.73 and 1.90 µg g-1. In cigarette samples the results were 0.085 and 0.193 µg g-1, and in food samples (coriander and lettuce) the concentrations found of this metal were, respectively, 0.33 and 0.12 µg g-1.

  16. Evaluation of calcium alginate beads for Ce, La and Nd preconcentration from groundwater prior to ICP OES analysis.

    PubMed

    Arantes de Carvalho, Gabriel G; Kondaveeti, Stalin; Petri, Denise F S; Fioroto, Alexandre M; Albuquerque, Luiza G R; Oliveira, Pedro V

    2016-12-01

    Analytical methods for the determination of rare earth elements (REE) in natural waters by plasma spectrochemical techniques often require sample preparation procedures for analytes preconcentration as well as for removing matrix constituents, that may interfere on the analytical measurements. In the present work, calcium alginate (CA) beads were used for the first time aiming at Ce, La and Nd preconcentration from groundwater samples for further determination by inductively coupled plasma optical emission spectrometry (ICP OES). Test samples were analyzed in batch mode by transferring a 40mL test portion (pH=5±0.2) into a 50mL polyethylene flask containing 125mg CA beads. After 15min contact, the analytes were quantitatively extracted from the loaded CA beads with 2.0mL of 1.0molL(-1) HCl solution for further determination by ICP OES, using Ce (II) 456.236, La (II) 379.478 and Nd (II) 430.358nm emission lines. The proposed approach is a reliable alternative for REE single-stage preconcentration from aqueous samples, as it provided accurate results based on the addition and recovery analysis of groundwater. The results obtained by the proposed method were also compared with those from reference method based on inductively coupled plasma mass spectrometry (ICP-MS) and no significant differences were observed after applying the Student's t-test at 95% confidence level.

  17. Application of dispersive liquid-liquid-solidified floating organic drop microextraction and ETAAS for the preconcentration and determination of indium.

    PubMed

    Ashrafzadeh Afshar, Elham; Taher, Mohammad Ali; Fazelirad, Hamid; Naghizadeh, Matin

    2017-03-01

    A new, simple and efficient method, including dispersive liquid-liquid-solidified floating organic drop microextraction and then electrothermal atomic absorption spectrometry, has been developed for the preconcentration and determination of ultratrace amounts of indium. The method was applied to preconcentrate the indium-1-(2-pyridylazo)-2-naphthol complex in 25 μL 1-undecanol. The various factors affecting the extraction efficiency, such as pH, type and volume of extraction solvent, type and volume of disperser solvent, sample volume, ionic strength, and ligand concentration, were investigated and optimized. Under the optimum conditions, an enrichment factor of 62.5, precision of ±4.75%, a detection limit of 55.6 ng L(-1), and for the calibration graph a linear range of 96.0-3360 ng L(-1) were obtained. The method was used for the extraction and determination of indium in water and standard samples with satisfactory results. Graphical Abstract Preconcentration of indium ions via liquid-liquid-solidified floating organic drop microextraction method and determination by ETAAS.

  18. Resting eggs as new biosorbent for preconcentration of trace elements in various samples prior to their determination by FAAS.

    PubMed

    Saçmacı, Serife; Yılmaz, Yakup; Kartal, Senol; Kaya, Murat; Duman, Fatih

    2014-06-01

    In this study, the resting eggs of aquatic creatures living in freshwater (Daphnia, Cladocera, Crustacean) ecosystems were used as a novel biosorbent extractant for synchronous preconcentration of trace Cd(II), Co(II), Cu(II), Mn(II), and Ni(II) previous to measurement by flame atomic absorpiton spectrometry (FAAS). Using column procedures, optimization studies were conducted to realize the effective adsorption of the analyte ions such as the solution pH, amount of the biosorbent, volume of the sample, interfering ions, etc. A high preconcentration factor of 67 and low relative standard deflection of ≤4.1% (n=8) were obtained. The invention constrains based on the 3 s/b criterion were 2.4 for Cd(II), 41.4 for Co(II), 4.2 for Cu(II), 3.0 for Mn(II), and 9.6 μg L(-1) for Ni(II). The accuracy of the method was verified by analysis of a certified standard reference material. The used procedure was applied to the definition of the analytes in diverse environmental samples with convincing results. Consequently, the resting eggs of Daphnia can be used as a biosorbent for preconcentration and biosorption studies.

  19. Determination of arsenic in water samples by Total Reflection X-Ray Fluorescence using pre-concentration with alumina

    NASA Astrophysics Data System (ADS)

    Barros, Haydn; Marcó Parra, Lué-Merú; Bennun, Leonardo; Greaves, Eduardo D.

    2010-06-01

    The determination of arsenic in water samples requires techniques of high sensitivity. Total Reflection X-Ray Fluorescence (TXRF) allows the determination but a prior separation and pre-concentration procedure is necessary. Alumina is a suitable substrate for the selective separation of the analytes. A method for separation and pre-concentration in alumina, followed by direct analysis of the alumina is evaluated. Quantification was performed using the Al-Kα and Co-Kα lines as internal standard in samples prepared on an alumina matrix, and compared to a calibration with aqueous standards. Artificial water samples of As (III) and As (V) were analyzed after the treatment. Fifty milliliters of the sample at ppb concentration levels were mixed with 10 mg of alumina. The pH, time and temperature were controlled. The alumina was separated from the slurry by centrifugation, washed with de-ionized water and analyzed directly on the sample holder. A pre-concentration factor of 100 was found, with detection limit of 0.7 μgL -1. The percentage of recovery was 98% for As (III) and 95% for As (V) demonstrating the suitability of the procedure.

  20. 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.

  1. Sample Preconcentration Utilizing Nanofractures Generated by Junction Gap Breakdown Assisted by Self-Assembled Monolayer of Gold Nanoparticles

    PubMed Central

    Jen, Chun-Ping; Amstislavskaya, Tamara G.; Chen, Kuan-Fu; Chen, Yu-Hung

    2015-01-01

    The preconcentration of proteins with low concentrations can be used to increase the sensitivity and accuracy of detection. A nonlinear electrokinetic flow is induced in a nanofluidic channel due to the overlap of electrical double layers, resulting in the fast accumulation of proteins, referred to as the exclusion-enrichment effect. The proposed chip for protein preconcentration was fabricated using simple standard soft lithography with a polydimethylsiloxane replica. This study extends our previous paper, in which gold nanoparticles were manually deposited onto the surface of a protein preconcentrator. In the present work, nanofractures were formed by utilizing the self-assembly of gold-nanoparticle-assisted electric breakdown. This reliable method for nanofracture formation, involving self-assembled monolayers of nanoparticles at the junction gap between microchannels, also decreases the required electric breakdown voltage. The experimental results reveal that a high concentration factor of 1.5×104 for a protein sample with an extremely low concentration of 1 nM was achieved in 30 min by using the proposed chip, which is faster than our previously proposed chip at the same conditions. Moreover, an immunoassay of bovine serum albumin (BSA) and anti-BSA was carried out to demonstrate the applicability of the proposed chip. PMID:25970592

  2. Paper-based analytical device for sampling, on-site preconcentration and detection of ppb lead in water.

    PubMed

    Satarpai, Thiphol; Shiowatana, Juwadee; Siripinyanond, Atitaya

    2016-07-01

    A simple and cost effectiveness procedure based on a paper based analytical device (PAD) for sampling, on-site preconcentration and determination of Pb(II) in water samples was developed. The inkjet printing method was used for patterning of PAD. Colorimetric assay was developed on a PAD for Pb(II) detection in µgL(-1) level. This µgL(-1) level detection limit was achieved by in situ- and on-site preconcentration of Pb(II) onto adsorption filter paper disc with a home-made holder before color development. Water sample was loaded onto a circular filter paper coated with zirconium silicate in 3% sodium carboxymethylcellulose for Pb(II) preconcentration. Subsequently, sodium rhodizonate in tartrate buffer solution (pH 2.8) was used as colorimetric reagent for direct Pb(II) detection on a PAD. Detection was achieved by measuring the pink color and recorded by scanner or digital camera. ImageJ software was used for measuring grey scale values. The calibration curve was linear in the range of 10µgL(-1) and 100µgL(-1), with a detection limit of 10µgL(-1). The developed method was successfully applied to the determination of Pb(II) in drinking water, tap water and surface water near electronic waste storage and the results were compared with those by graphite furnace atomic absorption spectroscopy (GF-AAS) with good agreement.

  3. Medium chain triglyceride (MCT) rich, paclitaxel loaded self nanoemulsifying preconcentrate (PSNP): a safe and efficacious alternative to Taxol.

    PubMed

    Patel, Ketan; Patil, Anand; Mehta, Miten; Gota, Vikram; Vavia, Pradeep

    2013-12-01

    The current work was aimed to develop Medium Chain Triglyceride (MCT) rich self nanoemulsifying preconcentrate of paclitaxel (PTX) for parenteral delivery. Very high concentrations of Cremophor EL and ethanol in Taxol have rendered patients to severe side effects. Years of extensive research on development of cost effective and safer vehicle for PTX, have failed to provide a promising replacement for Taxol. MCT was selected as oil owing to its parenteral acceptability, high solubilization capacity and multiple therapeutic benefits in cancer cachexia. PTX precipitation kinetics and reported toxicity profile of Kolliphor HS15 has favored its selection for PTX Self Nanoemulsifying Preconcentrate (PSNP). Presence of 30% free PEG in Kolliphor HS15 (PEG-15-hydroxystearate) restricts its miscibility with MCT, imposing significant challenge in development of MCT rich self nanoemulsifying preconcentrate. Removal of PEG layer from oil-surfactant mixture facilitated the formulation of PSNP with 51% w/w MCT. PSNP exhibited better precipitation kinetic profile, higher PTX loading with negligible hemolysis and histamine release compared to Taxol. PSNP was bioequivalent to Taxol, though V(d) and MRT was significantly higher than Taxol. PSNP showed distinctly better profile in inhibiting tumor growth and maintaining body weight with significantly higher % survival. Thus, PSNP can be a safer vehicle with potential clinical benefits.

  4. 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.

  5. Use of cloud-point preconcentration for spectrophotometric determination of trace amounts of antimony in biological and environmental samples.

    PubMed

    El-Sharjawy, Abdel-Azeem M; Amin, Alaa S

    2016-01-01

    This work presents a cloud-point extraction process using the micelle-mediated extraction method for simultaneous preconcentration and determination of Sb(III) and Sb(V) species in biological and environmental samples as a prior preconcentration step to their spectrophotometric determination. The analytical system is based on the selective reaction between Sb(III) and 3-dichloro-6-(3-carboxy-2-hydroxy-1-naphthylazo)quinoxaline (DCHNAQ) in the presence of cetyltrimethylammonium bromide (CTAB) and potassium iodide at pH 4.5. Total Sb concentration was determined after reduction of Sb(V) to Sb(III) in the presence of potassium iodide and ascorbic acid. The optimal reaction conditions and extraction were studied, and the analytical characteristics of the method (e.g., limits of detection and quantification, linear range, preconcentration, improvement factors) were obtained. Linearity for Sb(III) was obeyed in the range of 0.2-20 ng ml(-1). The detection and quantification limits for the determination of Sb(III) were 0.055 and 0.185 ng ml(-1), respectively. The method has a lower detection limit and wider linear range, inexpensive instrument, and low cost, and is more sensitive compared with most other methods. The interference effect of some anions and cations was also studied. The method was applied to the determination of Sb(III) in the presence of Sb(V) and total antimony in blood plasma, urine, biological, and water samples.

  6. Effects of Requiring Students to Meet High Expectation Levels within an On-Line Homework Environment

    ERIC Educational Resources Information Center

    Weber, William J., Jr.

    2010-01-01

    On-line homework is becoming a larger part of mathematics classrooms each year. Thus, ways to maximize the effectiveness of on-line homework for both students and teachers must be investigated. This study sought to provide one possible answer to this aim, by requiring students to achieve at least 50% for any on-line homework assignment in order to…

  7. Women Physicians Are Early Adopters of On-Line Continuing Medical Education

    ERIC Educational Resources Information Center

    Harris, John M., Jr.; Novalis-Marine, Cheryl; Harris, Robin B.

    2003-01-01

    Introduction: On-line continuing medical education (CME) provides advantages to physicians and to medical educators. Although practicing physicians increasingly use on-line CME to meet their educational needs, the overall use of on-line CME remains limited. There are few data to describe the physicians who use this new educational medium; yet,…

  8. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  9. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  10. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  11. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  12. 21 CFR 870.4330 - Cardiopulmonary bypass on-line blood gas monitor.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass on-line blood gas monitor... Cardiopulmonary bypass on-line blood gas monitor. (a) Identification. A cardiopulmonary bypass on-line blood gas monitor is a device used in conjunction with a blood gas sensor to measure the level of gases in the...

  13. Designing and Teaching an On-Line Course: Spinning Your Web Classroom.

    ERIC Educational Resources Information Center

    Schweizer, Heidi

    This guide to developing and teaching an on-line course is intended to lead the instructor through the steps of course development, on-line teaching, and on-line assessment. It emphasizes principles of course design which are outcome-based, performance-assessed, and collaborative. The guide's nine chapters cover the following aspects of course…

  14. 77 FR 55811 - Manufacturing Extension Partnership Advisory Board On-line Open Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-11

    ... National Institute of Standards and Technology Manufacturing Extension Partnership Advisory Board On-line... Manufacturing Extension Partnership (MEP) Advisory Board will hold an open, on-line meeting via webcast on... their remote location. Questions regarding the on-line meeting should be sent to the...

  15. Stress Caused by On-Line Collaboration in E-Learning: A Developing Model

    ERIC Educational Resources Information Center

    Allan, John; Lawless, Naomi

    2003-01-01

    On-line collaboration is becoming increasingly common in education and in organisations. It was believed that this could in itself cause stress for collaborators. An analysis of on-line learning diaries, phone interviews and questionnaires indicated that on-line collaboration could cause stress, and this stress was linked to the dependency of the…

  16. The effect of family therapy on the changes in the severity of on-line game play and brain activity in adolescents with on-line game addiction.

    PubMed

    Han, Doug Hyun; Kim, Sun Mi; Lee, Young Sik; Renshaw, Perry F

    2012-05-31

    We evaluated whether a brief 3-week family therapy intervention would change patterns of brain activation in response to affection and gaming cues in adolescents from dysfunctional families who met criteria for on-line game addiction. Fifteen adolescents with on-line game addiction and fifteen adolescents without problematic on-line game play and an intact family structure were recruited. Over 3 weeks, families were asked to carry out homework assignments focused on increasing family cohesion for more than 1 hour/day and 4 days/week. Before therapy, adolescents with on-line game addiction demonstrated decreased activity as measured by functional magnetic resonance imaging (fMRI) within the caudate, middle temporal gyrus, and occipital lobe in response to images depicting parental affection and increased activity of the middle frontal and inferior parietal in response scenes from on-line games, relative to healthy comparison subjects. Improvement in perceived family cohesion following 3 weeks of treatment was associated with an increase in the activity of the caudate nucleus in response to affection stimuli and was inversely correlated with changes in on-line game playing time. With evidence of brain activation changes in response to on-line game playing cues and images depicting parental love, the present findings suggest that family cohesion may be an important factor in the treatment of problematic on-line game playing.

  17. Self-checking on-line testable static RAM

    NASA Technical Reports Server (NTRS)

    Chau, Savio N. (Inventor); Rennels, David A. (Inventor)

    1993-01-01

    This is a fault-tolerant random access memory for use in fault-tolerant computers. It comprises a plurality of memory chips each comprising a plurality of on-line testable and correctable memory cells disposed in rows and columns for holding individually addressable binary bits and provision for error detection incorporated into each memory cell for outputting an error signal whenever a transient error occurs therein. In one embodiment, each of the memory cells comprises a pair of static memory sub-cells for simultaneously receiving and holding a common binary data bit written to the memory cell and the error detection provision comprises comparator logic for continuously sensing and comparing the contents of the memory sub-cells to one another and for outputting the error signal whenever the contents do not match. In another embodiment, each of the memory cells comprises a static memory sub-cell and a dynamic memory sub-cell for simultaneously receiving and holding a common binary data bit written to the memory cell and the error detection provision comprises comparator logic for continuously sensing and comparing the contents of the static memory sub-cell to the dynamic memory sub-cell and for outputting the error signal whenever the contents do not match. Capability for correction of errors is also included.

  18. On-Line Measurement Of Hot Rolling Steel Bar

    NASA Astrophysics Data System (ADS)

    Feng, Chen

    1989-03-01

    A passive instrument for on-line measuring hot rolling steel bar has been developed. The instrument uses self emission of the hot steel bar to deside the profile of working piece. The instrument can measure the dimensions of the cross section of the high speed and high temperature steel bar on the production line. It can be used for real-time monitoring, evaluating, and controlling the quality of the products. Compared with other similar instrument, new instrument has following features: - Passive measurement for simplifying the structure; - Simultaneous dimension and position measurement for ensuring high accuracy; - Temperature measurement for compensating thermal error; - Solid state sensor array for raising reliability; - Special structure for running in hostile enviornment; All these features make it possible to realize accurate measurement in high temperature, high humidity, and high dusty circumstance. The paper will present and discuss relative problems in the design and construction of this instrument. A prototype has been made and a series analogue experiments have been carried out in the laboratory. Rolling shop running test approves that the instrument can accurately measure the hot rolling steel bar on the production line. The total error is less than 0.05 mm while the measuring rate is as high as 2000 samples per second.

  19. The on-line low temperature nuclear orientation facility NICOLE

    NASA Astrophysics Data System (ADS)

    Ohtsubo, T.; Roccia, S.; Stone, N. J.; Stone, J. R.; Gaulard, C.; Köster, U.; Nikolov, J.; Simpson, G. S.; Veskovic, M.

    2017-04-01

    We review major experiments and results obtained by the on-line low temperature nuclear orientation method at the NICOLE facility at ISOLDE, CERN since the year 2000 and highlight their general physical impact. This versatile facility, providing a large degree of controlled nuclear polarization, was used for a long-standing study of magnetic moments at shell closures in the region Z = 28, N = 28–50 but also for dedicated studies in the deformed region around A ∼ 180. Another physics program was conducted to test symmetry in the weak sector and constrain weak coupling beyond V–A. Those two programs were supported by careful measurements of the involved solid state physics parameters to attain the full sensitivity of the technique and provide interesting interdisciplinary results. Future plans for this facility include the challenging idea of measuring the beta–gamma–neutron angular distributions from polarized beta delayed neutron emitters, further test of fundamental symmetries and obtaining nuclear structure data used in medical applications. The facility will also continue to contribute to both the nuclear structure and fundamental symmetry test programs.

  20. On-line monitoring of methane in sewer air

    PubMed Central

    Liu, Yiwen; Sharma, Keshab R.; Murthy, Sudhir; Johnson, Ian; Evans, Ted; Yuan, Zhiguo

    2014-01-01

    Methane is a highly potent greenhouse gas and contributes significantly to climate change. Recent studies have shown significant methane production in sewers. The studies conducted so far have relied on manual sampling followed by off-line laboratory-based chromatography analysis. These methods are labor-intensive when measuring methane emissions from a large number of sewers, and do not capture the dynamic variations in methane production. In this study, we investigated the suitability of infrared spectroscopy-based on-line methane sensors for measuring methane in humid and condensing sewer air. Two such sensors were comprehensively tested in the laboratory. Both sensors displayed high linearity (R2 > 0.999), with a detection limit of 0.023% and 0.110% by volume, respectively. Both sensors were robust against ambient temperature variations in the range of 5 to 35°C. While one sensor was robust against humidity variations, the other was found to be significantly affected by humidity. However, the problem was solved by equipping the sensor with a heating unit to increase the sensor surface temperature to 35°C. Field studies at three sites confirmed the performance and accuracy of the sensors when applied to actual sewer conditions, and revealed substantial and highly dynamic methane concentrations in sewer air. PMID:25319343

  1. An On-Line Database of APS POSS Images

    NASA Astrophysics Data System (ADS)

    Cornuelle, C. S.; Aldering, G.; Sourov, A.; Thurmes, P.; Humphreys, R. M.

    We are making available our digitized images from the APS scans of the red and blue first-epoch Palomar Observatory Sky Survey (POSS I) photographic plates, forming an on-line image database. Image requests are through the APS homepage at URL http://isis.spa.umn.edu/homepage.aps.html and are initially limited in field width and sky region. To create this database, images from each scanned POSS I plate are processed into a set of coordinate-referenced index and pixel files. Database management software then refers to each object's pixels within a requested sky region by plate, by sub-plate, and finally by each scanned image. These images are then assembled into a mosaic FITS format file, whose header contains astrometric and photometric information. While the current APS Catalog of the POSS I includes only matched images, the image database will include images above 25 mu m in diameter. Thus for a given sky region, users have access to both the object (star and galaxy) catalog data and to the actual pixel data. This project is sponsored by NASA ADP contract NAS5-32670.

  2. EnviroNET: On-line information for LDEF

    NASA Technical Reports Server (NTRS)

    Lauriente, Michael

    1993-01-01

    EnviroNET is an on-line, free-form database intended to provide a centralized repository for a wide range of technical information on environmentally induced interactions of use to Space Shuttle customers and spacecraft designers. It provides a user-friendly, menu-driven format on networks that are connected globally and is available twenty-four hours a day - every day. The information, updated regularly, includes expository text, tabular numerical data, charts and graphs, and models. The system pools space data collected over the years by NASA, USAF, other government research facilities, industry, universities, and the European Space Agency. The models accept parameter input from the user, then calculate and display the derived values corresponding to that input. In addition to the archive, interactive graphics programs are also available on space debris, the neutral atmosphere, radiation, magnetic fields, and the ionosphere. A user-friendly, informative interface is standard for all the models and includes a pop-up help window with information on inputs, outputs, and caveats. The system will eventually simplify mission analysis with analytical tools and deliver solutions for computationally intense graphical applications to do 'What if...' scenarios. A proposed plan for developing a repository of information from the Long Duration Exposure Facility (LDEF) for a user group is presented.

  3. Building collaboration tools and access to on-line facilities

    SciTech Connect

    Agarwal, D.; Sachs, S.

    1996-11-01

    Network-based facilities will allow researchers at different locations to collaborate on experiments as if they all were together in the same laboratory. The expected value of these geographically distributed environments includes substantially increased effectiveness in doing science, and an enabling capability for analytical and high-value production use by industry. The Distributed, Collaboratory Experiment Environments (DCEE) Program consists of four projects that were established to build prototype remote experiment and collaborative environments. The work undertaken in this project represents some of the research and development of the mechanisms and infrastructure required to make collaboratories a reality. Some of these mechanisms have already been developed. Several other mechanisms, such as data dissemination, resource management for the sharing of experiment control, safety and security, electronic notebooks, elements of telepresence, and integrated user interfaces need further research and development. The pilot application for these collaborative tools is the Advanced Light Source (ALS) Beamline 7.0 at the Ernest Orlando Lawrence Berkeley Laboratory. The ALS is a particle accelerator and is a source of very high brilliance soft X-ray beams. One experimental facility is the Spectro-Microscopy Facility Beamline 7.0. Through this project, the Spectro-Microscopy Facility will be opened up to users from a wide range of organizations. The goal is to build software that will not only put the ALS Beamline 7.0 on-line, but will also serve as building blocks for future collaboratory development.

  4. On-line optical sensors for industrial material inspection

    NASA Astrophysics Data System (ADS)

    Cielo, Paolo G.

    1990-08-01

    In the modem computer-integrated material processing plant statistical process control plays an increasingly important role. A corresponding need for rugged and noninvasive on-line sensors capable of reliable and unattended performance is becoming more and more urgent. Optical sensors are often being adopted for such tasks not only because of their noncontact nature implying an easy adaptability to the automated inspection of continuously moving products at any temperature but also in view of their high response speed intrinsic resolution and increasing ruggedness. Properties which may be probed with optical devices include product features such as geometrical size and shape or surface integrity as well as process parameters such as temperature speed or vibration amplitude. This paper reviews a number of optical sensors which were recently developed at our institute for industrial material online inspection. Examples include surface defect detection 3-D lumber board scanning and infrared temperature measurement either in furnace or during spray deposition. The emphasis is on noncontact techniques well suited to automation and specifically adapted to each particular application with minimum perturbation of the industrial process. 1.

  5. Using on-line altered auditory feedback treating Parkinsonian speech

    NASA Astrophysics Data System (ADS)

    Wang, Emily; Verhagen, Leo; de Vries, Meinou H.

    2005-09-01

    Patients with advanced Parkinson's disease tend to have dysarthric speech that is hesitant, accelerated, and repetitive, and that is often resistant to behavior speech therapy. In this pilot study, the speech disturbances were treated using on-line altered feedbacks (AF) provided by SpeechEasy (SE), an in-the-ear device registered with the FDA for use in humans to treat chronic stuttering. Eight PD patients participated in the study. All had moderate to severe speech disturbances. In addition, two patients had moderate recurring stuttering at the onset of PD after long remission since adolescence, two had bilateral STN DBS, and two bilateral pallidal DBS. An effective combination of delayed auditory feedback and frequency-altered feedback was selected for each subject and provided via SE worn in one ear. All subjects produced speech samples (structured-monologue and reading) under three conditions: baseline, with SE without, and with feedbacks. The speech samples were randomly presented and rated for speech intelligibility goodness using UPDRS-III item 18 and the speaking rate. The results indicted that SpeechEasy is well tolerated and AF can improve speech intelligibility in spontaneous speech. Further investigational use of this device for treating speech disorders in PD is warranted [Work partially supported by Janus Dev. Group, Inc.].

  6. On-line DNA analysis system with rapid thermal cycling

    DOEpatents

    Swerdlow, Harold P.; Wittwer, Carl T.

    1999-01-01

    An apparatus particularly suited for subjecting biological samples to any necessary sample preparation tasks, subjecting the sample to rapid thermal cycling, and then subjecting the sample to subsequent on-line analysis using one or more of a number of analytical techniques. The apparatus includes a chromatography device including an injection means, a chromatography pump, and a chromatography column. In addition, the apparatus also contains a capillary electrophoresis device consisting of a capillary electrophoresis column with an inlet and outlet end, a means of injection, and means of applying a high voltage to cause the differential migration of species of interest through the capillary column. Effluent from the liquid chromatography column passes over the inlet end of the capillary electrophoresis column through a tee structure and when the loading of the capillary electrophoresis column is desired, a voltage supply is activated at a precise voltage and polarity over a specific duration to cause sample species to be diverted from the flowing stream to the capillary electrophoresis column. A laser induced fluorescence detector preferably is used to analyze the products separated while in the electrophoresis column.

  7. On-line DNA analysis system with rapid thermal cycling

    DOEpatents

    Swerdlow, H.P.; Wittwer, C.T.

    1999-08-10

    This application describes an apparatus particularly suited for subjecting biological samples to any necessary sample preparation tasks, subjecting the sample to rapid thermal cycling, and then subjecting the sample to subsequent on-line analysis using one or more of a number of analytical techniques. The apparatus includes a chromatography device including an injection means, a chromatography pump, and a chromatography column. In addition, the apparatus also contains a capillary electrophoresis device consisting of a capillary electrophoresis column with an inlet and outlet end, a means of injection, and means of applying a high voltage to cause the differential migration of species of interest through the capillary column. Effluent from the liquid chromatography column passes over the inlet end of the capillary electrophoresis column through a tee structure and when the loading of the capillary electrophoresis column is desired, a voltage supply is activated at a precise voltage and polarity over a specific duration to cause sample species to be diverted from the flowing stream to the capillary electrophoresis column. A laser induced fluorescence detector preferably is used to analyze the products separated while in the electrophoresis column. 6 figs.

  8. On-Line Loss of Control Detection Using Wavelets

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J. (Technical Monitor); Thompson, Peter M.; Klyde, David H.; Bachelder, Edward N.; Rosenthal, Theodore J.

    2005-01-01

    Wavelet transforms are used for on-line detection of aircraft loss of control. Wavelet transforms are compared with Fourier transform methods and shown to more rapidly detect changes in the vehicle dynamics. This faster response is due to a time window that decreases in length as the frequency increases. New wavelets are defined that further decrease the detection time by skewing the shape of the envelope. The wavelets are used for power spectrum and transfer function estimation. Smoothing is used to tradeoff the variance of the estimate with detection time. Wavelets are also used as front-end to the eigensystem reconstruction algorithm. Stability metrics are estimated from the frequency response and models, and it is these metrics that are used for loss of control detection. A Matlab toolbox was developed for post-processing simulation and flight data using the wavelet analysis methods. A subset of these methods was implemented in real time and named the Loss of Control Analysis Tool Set or LOCATS. A manual control experiment was conducted using a hardware-in-the-loop simulator for a large transport aircraft, in which the real time performance of LOCATS was demonstrated. The next step is to use these wavelet analysis tools for flight test support.

  9. Virtual laboratories: Collaborative environments and facilities-on-line

    SciTech Connect

    Thomas, C.E. Jr.; Cavallini, J.S.; Seweryniak, G.R.; Kitchens, T.A.; Hitchcock, D.A.; Scott, M.A.; Welch, L.C.; Aiken, R.J. |; Stevens, R.L.

    1995-07-01

    The Department of Energy (DOE) has major research laboratories in a number of locations in the US, typically co-located with large research instruments or research facilities valued at tens of millions to even billions of dollars. Present budget exigencies facing the entire nation are felt very deeply at DOE, just as elsewhere. Advances over the last few years in networking and computing technologies make virtual collaborative environments and conduct of experiments over the internetwork structure a possibility. The authors believe that development of these collaborative environments and facilities-on-line could lead to a ``virtual laboratory`` with tremendous potential for decreasing the costs of research and increasing the productivity of their capital investment in research facilities. The majority of these cost savings would be due to increased productivity of their research efforts, better utilization of resources and facilities, and avoiding duplication of expensive facilities. A vision of how this might all fit together and a discussion of the infrastructure necessary to enable these developments is presented.

  10. Development of on-line laser power monitoring system

    NASA Astrophysics Data System (ADS)

    Ding, Chien-Fang; Lee, Meng-Shiou; Li, Kuan-Ming

    2016-03-01

    Since the laser was invented, laser has been applied in many fields such as material processing, communication, measurement, biomedical engineering, defense industries and etc. Laser power is an important parameter in laser material processing, i.e. laser cutting, and laser drilling. However, the laser power is easily affected by the environment temperature, we tend to monitor the laser power status, ensuring there is an effective material processing. Besides, the response time of current laser power meters is too long, they cannot measure laser power accurately in a short time. To be more precisely, we can know the status of laser power and help us to achieve an effective material processing at the same time. To monitor the laser power, this study utilize a CMOS (Complementary metal-oxide-semiconductor) camera to develop an on-line laser power monitoring system. The CMOS camera captures images of incident laser beam after it is split and attenuated by beam splitter and neutral density filter. By comparing the average brightness of the beam spots and measurement results from laser power meter, laser power can be estimated. Under continuous measuring mode, the average measuring error is about 3%, and the response time is at least 3.6 second shorter than thermopile power meters; under trigger measuring mode which enables the CMOS camera to synchronize with intermittent laser output, the average measuring error is less than 3%, and the shortest response time is 20 millisecond.

  11. A fully automated and fast method using direct sample injection combined with fused-core column on-line SPE-HPLC for determination of ochratoxin A and citrinin in lager beers.

    PubMed

    Lhotská, Ivona; Šatínský, Dalibor; Havlíková, Lucie; Solich, Petr

    2016-05-01

    A new fast and sensitive method based on on-line solid-phase extraction on a fused-core precolumn coupled to liquid chromatography with fluorescence detection has been developed for ochratoxin A (OTA) and citrinin (CIT) determination in lager beer samples. Direct injection of 100 μL filtered beer samples into an on-line SPE-HPLC system enabled fast and effective sample extraction including separation in less than 6 min. Preconcentration of OTA and CIT from beer samples was performed on an Ascentis Express RP C18 guard column (5 × 4.6 mm), particle size 2.7 μm, with a mobile phase of methanol/0.5% aqueous acetic acid pH 2.8 (30:70, v/v) at a flow rate of 2.0 mL min(-1). The flow switch from extraction column to analytical column in back-flush mode was set at 2.0 min and the separation was performed on the fused-core column Ascentis Express Phenyl-Hexyl (100 × 4.6 mm), particle size 2.7 μm, with a mobile phase acetonitrile/0.5% aqueous acetic acid pH 2.8 in a gradient elution at a flow rate of 1.0 mL min(-1) and temperature of 50 °C. Fluorescence excitation/emission detection wavelengths were set at 335/497 nm. The accuracy of the method, defined as the mean recoveries of OTA and CIT from light and dark beer samples, was in the range 98.3-102.1%. The method showed high sensitivity owing to on-line preconcentration; LOQ values were found to be 10 and 20 ng L(-1) for OTA and CIT, respectively. The found values of OTA and CIT in all tested light, dark and wheat beer samples were significantly below the maximum tolerable limits (3.0 μg kg(-1) for OTA and 2000 μg kg(-1) for CIT) set by the European Union.

  12. Determination of trace indium in urine after preconcentration with a chelating-resin-packed minicolumn.

    PubMed

    Liu, Hui-Ming; Chang, Ching-Yao; Wu, Chia-Chan; Wei, Jian-Ming; Chen, Wei-Yu; Yeh, Cheng-Tsung

    2012-04-01

    A simple and rapid chelating-resin-packed column has been developed for preconcentration of trace indium in biological samples. A large-sized urine sample was pumped through a minicolumn at a flow rate of 1.0 mL/min by using a peristaltic pump, and the eluents were analyzed using graphite furnace atomic absorption spectrometry (GFAAS). Four commercially available chelating resins including Chelex-100, Amberlite IRC-50, Duolite GT-73, and Celite 545-AW were studied for evaluating the indium sorption performance. Several parameters, such as pH, resin amount, eluent volume, eluent flow rate, and the volume of sample, were investigated and optimized. A 100-200 mL of the sample was loaded into a column containing 1.2 g of wet Chelex-100 and subjected to the ion-exchange procedure. The retained analytes were eluted with 5.0 mL of 0.1 M HNO(3) and quantified by GFAAS. The correlation coefficient in the range 10-250 ng/mL was of 0.9994. The limit of detection of the proposed method was 2.75 ng/mL. The method developed was successfully applied to analysis of spiked urine samples with good recoveries of 93-103% (n = 6) and reproducibility (relative standard deviation < 4.9%). The accuracy of procedure was confirmed by indium determination in spiked certified reference materials.

  13. Electromembrane extraction and preconcentration of carbendazim and thiabendazole in water samples before capillary electrophoresis analysis.

    PubMed

    Oliveira, Amilton Moreira; Loureiro, Hugo Campos; Jesus, Francielly Fernanda Souza; de Jesus, Dosil Pereira

    2017-02-06

    Electromembrane extraction using a polypropylene hollow fiber impregnated with 1-ethyl-2-nitrobenzene was evaluated for the extraction and preconcentration of the fungicides thiabendazole and carbendazim from water samples before capillary electrophoresis analysis. The composition of the supported liquid membrane, the HCl concentration in the acceptor solution, and the stirring rate (of the donor solution) were optimized using the one-variable-at-a-time method. In contrast, a face-centered central composition design was used for optimization of voltage, extraction time, and concentration of HCl in the donor solution. After optimization, electromembrane extraction provided enrichment factors of 50 and 26 for thiabendazole and carbendazim that allowed us to achieve limits of detection of 1.1 and 2.3 μg L(-1) , respectively. Repeatability (intra-day precision) expressed as the relative standard deviation varied from 2.5 to 2.8%, while the inter-day precision ranged from 3.1 to 3.3%. The proposed method was applied for analysis of samples of tap and river water, and acceptable precision and accuracy were attained. This article is protected by copyright. All rights reserved.

  14. On-chip DNA preconcentration in different media conductivities by electrodeless dielectrophoresis.

    PubMed

    Li, Shunbo; Ye, Ziran; Hui, Yu Sanna; Gao, Yibo; Jiang, Yusheng; Wen, Weijia

    2015-09-01

    Electrodeless dielectrophoresis is the best choice to achieve preconcentration of nanoparticles and biomolecules due to its simple, robust, and easy implementation. We designed a simple chip with microchannels and nano-slits in between and then studied the trapping of DNA in high conductive medium and low conductive medium, corresponding to positive and negative dielectrophoresis (DEP), respectively. It is very important to investigate the trapping in media with different conductivities since one always has to deal with the sample solutions with different conductivities. The trapping process was analyzed by the fluorescent intensity changes. The results showed that DNA could be trapped at the nano-slit in both high and low conductive media in a lower electric field strength (10 V/cm) compared to the existing methods. This is a significant improvement to suppress the Joule heating effect in DEP related experiments. Our work may give insight to researchers for DNA trapping by a simple and low cost device in the Lab-on-a-Chip system.

  15. Improved performance of micro-fabricated preconcentrators using silica nanoparticles as a surface template.

    PubMed

    Akbar, Muhammad; Wang, Dong; Goodman, Ryan; Hoover, Ashley; Rice, Gary; Heflin, James R; Agah, Masoud

    2013-12-27

    A new approach of enhancing the adsorption capability of the widely used polymer adsorbent Tenax TA poly(2,6-diphenylene oxide) through its deposition on a nano-structured template is reported. The modified Tenax TA-coated silica nanoparticles (SNP) are incorporated as an adsorbent bed in silicon based micro-thermal preconcentrator (μTPC) chips with an array of square microposts embedded inside the cavity and sealed with a Pyrex cover. The interior surface of the chip is first modified by depositing SNP using a layer-by-layer self-assembly technique followed by coating with Tenax TA. The adsorption capacity of the SNP-Tenax TA μTPC is enhanced by as much as a factor of three compared to the one coated solely with thin film Tenax TA for the compounds tested. The increased adsorption ability of the Tenax TA is attributed to the higher surface area provided by the underlying porous SNP coating and the pores between SNPs affecting the morphology of deposited Tenax TA film by bringing nano-scale features into the polymer. In addition, the adsorption ability of the SNP coating as a pseudo-selective inorganic adsorption bed for polar compounds was also observed. The modified Tenax TA-coated SNP μTPC is a promising development toward integrated micro-gas chromatography systems.

  16. Dissimilar viscosity induced sample pre-concentration in elecrokinetic nanofluidic channels

    NASA Astrophysics Data System (ADS)

    Wink, Dean; Shelton, Elijah; Pennathur, Sumita; Storey, Brian

    2013-11-01

    Nanofluidic analysis systems boast many advantages: portability, small sample handling, short processing times, and potential for integration with mobile electronics. However, such systems face the challenge of detecting increasingly small volumes of sample at low concentrations. In this work, we demonstrate a unique pre-concentration technique in electrokinetic nanofluidic systems based on a viscosity mismatch between two fluids. In nanofluidic electrokinetic systems, finite electric double layers (EDL) lead to non-uniform electric potentials and transverse concentration distributions. Therefore, when the EDL is comparable in size to the channel height, negatively charged ions are repelled from negatively charged walls and preferentially populate the channel centerline. Furthermore, an axial piecewise viscosity distribution induces internal pressure gradients within the channel. These force the ions to move at a different average velocities based on the pressure gradient being favorable or adverse, leading to focusing. To experimentally probe this phenomenon, we electrokinetically inject solutions of borate buffer with and without glycerol (to change the viscosity) and use a fluorescent tracer dye to visualize the flow. We perform the injections in cross-geometry channels of 20 micron, 1 micron, and 250 nanometer depths. We measure fluorescence at 5, 10 and 15 mm distances from junction. Enhancement is characterized by comparing intensities to control measurements for systems with uniform viscosity.

  17. Separation and preconcentration of cadmium ions using octadecyl silica membrane disks modified by methyltrioctylammonium chloride.

    PubMed

    Haji Shabani, Ali Mohammad; Dadfarnia, Shayesteh; Motavaselian, Fatemeh; Ahmadi, Seyyed Hamid

    2009-02-15

    A simple and selective method for the determination of cadmium in water samples by FAAS after solid phase extraction has been developed. The method is based on the sorption of cadmium as CdI(4)(2-) on octadecyl silica membrane disks modified by cationic surfactant of methyltrioctylammonium chloride in the pH range of 1-8. The sorbed cadmium is then eluted with 10ml of 1moll(-1) nitric acid in ethanol and is measured by flame atomic absorption spectrometry. The influence of flow rates of eluent and sample solution, iodide concentration and amount of surfactant in retention and elution of cadmium from disks was also investigated. A preconcentration factor of 100 was achieved by passing 1000ml of sample through the membrane disk. The limit of detection (LOD) of cadmium was found to be 0.014ngml(-1). Precision at 2.5mugl(-1) was 1.2% (n=8). The method was successfully applied to the determination of cadmium in some natural water samples. The accuracy was assessed through recovery experiment, independent analysis by graphite furnace atomic absorption spectrometry, and analysis of certified reference waters.

  18. Homogeneous liquid-liquid extraction method for the selective separation and preconcentration of ultra trace molybdenum.

    PubMed

    Ghiasvand, A R; Shadabi, S; Mohagheghzadeh, E; Hashemi, P

    2005-05-15

    A new simple and efficient homogeneous liquid-liquid extraction method for the selective separation and preconcentration of molybdenyl ions was developed. alpha-Benzoin oxime (ABO) was investigated as a complexing ligand, and perfluorooctanoate ion (PFOA(-)) was applied as a phase-separator agent under strongly acidic conditions. Under the optimal conditions ([ABO]=2.1x10(-3)M, [PFOA(-)]=1.8x10(-2)M, [HNO(3)]=1.7M, [acetone]=11.8% (v/v)), 10mug of molybdenum in 5ml aqueous phase could be extracted quantitatively into 40mul of the sedimented phase. The maximum concentration factor was 125-fold. Thiocyanate was applied as a chromogenic reagent for the direct spectrophotometric determination of molybdenum in the sedimented phase. The reproducibility of the proposed method is at the most 2.4%. The influence of the type and concentration of acid solution, the concentration of ABO, the type and volume of the water-miscible organic solvent, the concentration of PFOA(-), and the effect of different diverse ions on the extraction and determination of molybdenum(VI) were investigated. The proposed method was applied to the extraction and determination of molybdenum(VI) in natural water, Spinach, and Lucerne samples. A satisfactory agreement exists between the results obtained by the proposed method and those reported by GF-AAS.

  19. Trace analysis of phosphorus in water by sorption preconcentration and luminol chemiluminescence

    PubMed

    Zui; Birks

    2000-04-01

    A new, highly sensitive chemiluminescence method for the determination of sub-ppb quantities of phosphorus in water is described. The method is based on sorption preconcentration of phosphorus as a yellow vanadomolybdophosphoric heteropoly acid (HPA) in the presence or absence of a cationic surfactant on a paper filter, followed by direct chemiluminescence detection of the phosphorus concentrate via reaction with an alkaline luminol solution. The molar ratio of cationic surfactant to HPA in the ion associate sorbed on the filter is 4:1. The detection limits for phosphorus are 0.02 microgram of P L-1 in the presence of surfactant and 0.1 microgram of P L-1 in the absence of surfactant for a sample volume of 150 mL. The calibration plot is linear from 0.06 to 1.7 micrograms of P L-1 in the presence of a surfactant, and the time required for analysis is 25 min. In the absence of surfactant, the selectivities against Si4+ and As5+ are 5 and 40 times greater than those for the standard colorimetric method based on the formation of the blue molybdophosphoric HPA. Applications of the method to the analyses of river water, seawater, and the turbine vapor condensate from a coal-fired power plant are described. It is demonstrated that the sensitivity advantage of the chemiluminescence technique can be combined with the magnesium-induced coprecipitation (MAGIC) method for a more selective measurement of soluble reactive phosphorus.

  20. Separation and preconcentration of aluminum in parenteral solutions and bottled mineral water using different analytical techniques.

    PubMed

    Kazi, Tasneem G; Khan, Sumaira; Baig, Jameel A; Kolachi, Nida F; Afridi, Hassan I; Kandhro, Ghulam A; Kumar, Sham; Shah, Abdul Q

    2009-12-30

    A new method is reported for the separation of aluminum ions [Al(III)] from interfering elements in parenteral and pharmaceutical solutions (PS) and bottled mineral water (BMW) samples, through solid-phase extraction with 2-methyl-8-hydroxyquinoline (quinaldine) adsorbed onto activated silica gel. While the enrichment step of separated Al(III) was carried out by cloud point extraction (CPE) using 8-hydroxyquinoline as complexing reagent, the resulted complex was entrapped in a non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114). The enriched Al(III) in sample solutions were determined by spectrofluorometry (SPF) at lambda(excitation) 370 nm and lambda(emission) 510 nm, and flame atomic absorption spectrometry (FAAS) for comparative purpose. The variables affecting the complexation and extraction steps were studied and optimized. The validity of methodology was checked with certified reference material of water and standard addition method. The enrichment factor and detection limit of Al(III) for the preconcentration of 50 ml of PS and BMW were found to be 100 and 0.25 microg/L, respectively. The proposed method has been applied for the determination of trace amount of Al(III) in PS and BMW samples with satisfactory results. In PS the levels of Al(III) are above than permissible limit (25 microg/L).

  1. Sewage pre-concentration for maximum recovery and reuse at decentralized level.

    PubMed

    Diamantis, V; Verstraete, W; Eftaxias, A; Bundervoet, B; Siegfried, V; Melidis, P; Aivasidis, A

    2013-01-01

    Pre-concentration of municipal wastewater by chemically enhanced primary treatment (CEPT) was studied under controlled laboratory conditions. Both iron and aluminium-based coagulants were examined at gradually increasing concentrations (0.23, 0.35, 0.70 and 1.05 mmol/L). The CEPT sludge generated from different coagulation experiments was digested in batch anaerobic reactors, while the supernatant was tested in a dead-end microfiltration setup. The results of the study show that biogas yield was dramatically decreased (from 0.40 to 0.10 m(3)/kg chemical oxygen demand of influent) with increasing coagulant dose. In contrast, supernatant filterability was improved. Based on the laboratory results, a conceptual design was produced for a community of 2000 inhabitant equivalents (IE), using CEPT technology (at low coagulant dose) with anaerobic digestion of the concentrates. According to this, the capital and operational costs were 0.11 and 0.09 €/m(3), respectively. The biogas generated is used for digester heating and the overall process is energy self-sufficient. At a small-scale and in private applications, CEPT technology is preferably operated at higher coagulant dose, followed by membrane filtration for water reuse. Accordingly, sewage purification and reuse is possible without implementing aerobic biological processes.

  2. Preconcentration and Spectrophotometric Determination of a Naphthalene Analog of Medetomidine Using Modified Maghemite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Maddah, B.; Hosseini, F.; Ahmadi, M.; Rajabi, A. Asghar; Beik-Mohammadlood, Z.

    2016-05-01

    A novel and sensitive extraction procedure using sodium dodecyl sulfate (SDS) modified maghemite nanoparticles (MNPs) as an efficient solid phase has been developed for removal, preconcentration, and spectrophotometric determination of trace amounts of a naphthalene analog of dexmedetomidine (4-(1-(na phthalene-1-yl)ethyl)-1Himidazole, NMED). The MNPs were obtained by a coprecipitation method, and their surfaces were furthermore modified by SDS. The size and morphological properties of the synthesized MNPs were determined by X-ray diffraction analysis, FT-IR, vibrating sample magnetometry, and scanning electron microscopy. NMED was adsorbed at pH 3.0. The adsorbed drug was then desorbed and determined by spectrophotometry at 280 nm. The calibration graph was linear in the range 1 × 10-6-1 × 10-4 mol/L of NMED with a correlation coefficient of 0.989. The detection limit of the method for NMED determination was 3.7 × 10-7 mol/L. The method was successfully applied to the determination of NMED in human urine samples.

  3. Extraction and preconcentration of hemin from human blood serum and breast cancer supernatant.

    PubMed

    Sedaghat, Somayeh; Shamspur, Tayebeh; Mohamadi, Maryam; Mostafavi, Ali

    2015-12-01

    A green, facile, fast, and sensitive liquid-phase microextraction method is presented for the extraction and preconcentration of hemin in the presence of free iron ions prior to flame atomic absorption spectroscopic determination. In this technique, an anion-functionalized task-specific ionic liquid is used as the extracting solvent. The interface between the extracting solvent and the bulk aqueous phase containing hemin is enormously enlarged by dispersing the ionic liquid to the aqueous phase with the help of ultrasound radiation. Hemin is selectively extracted into the ionic liquid after interaction with the functional group of the ionic liquid. Then, the concentration of the extracted hemin is determined through the absorbance of the iron ions contained in the hemin structure using flame atomic absorption spectroscopy. Different experimental parameters affecting the extraction efficiency have been optimized. Under the optimized conditions, the proposed method has a hemin concentration linear range of 0.020-0.80 mg/L with a detection limit of 0.0080 mg/L. This method has been successfully applied to the extraction and determination of hemin in human serum and supernatant samples.

  4. Solid Phase Extraction and Preconcentration of Trace Gallium, Indium, and Thallium Using New Modified Amino Silica.

    PubMed

    Hassanien, Mohamed M; Mortada, Wael I; Kenawy, Ibrahim M; El-Daly, Heba

    2017-02-01

    Amino silica gel functionalized with 2-hydroxy-5 -(2-hydroxybenzylideneamino)benzoic acid was synthesized, characterized and used as adsorbent for the removal of Ga(3+), In(3+) and Tl(3+) from aqueous solution prior to their determination by flame atomic absorption spectrometry. Experimental parameters that affect the separation process were investigated in both batch and column modes. The maximum adsorption capacities of the sorbent are 61.7 mg g(-1), 81.3 mg g(-1) and 133.0 mg g(-1) for Ga(3+), In(3+) and Tl(3+), respectively. The preconcentration factor is 200 and the limits of detection of Ga(3+), In(3+) and Tl(3+) are 4.10 μg L(-1), 1.55 μg L(-1) and 1.21 μg L(-1), respectively. Interference by Al(3+) can be masked by the addition of F(-); and that of Fe(3+) by its reduction to Fe(2+) using 10% ascorbic acid. The method was successfully applied for the determination of these ions in water, sediments and liquid crystal display samples.

  5. Development and validation of a method using on-line solid-phase extraction and liquid chromatography with ultraviolet detection for the determination of bisphenol A, octylphenol, and nonylphenol in groundwater.

    PubMed

    Careri, M; Elviri, L; Mangia, A

    2001-01-01

    Alkylphenols are nonbiodegradable metabolites arising from various pathways of aerobic and anaerobic degradation of the nonionic surfactants alkylphenol ethoxylates. A method based on the use of on-line solid-phase extraction (SPE) and liquid chromatography (LC) with UV detection was developed to determine bisphenol A, octylphenol, and nonylphenol at trace levels in water. The on-line coupled SPE procedure automatically enables an approximately 300-fold preconcentration of analytes, which can be further enhanced by an increase in applied sample volume. By using C18 cartridges, recoveries of >90% were obtained for all the analytes. A validation procedure was carried out with a groundwater sample to ensure the quality of the results; performance criteria such as detection limits (LODs), quantitation limits (LOQs), linearity, and precision were evaluated. LODs and LOQs in the range of 0.17-0.36 and 0.35-1.88 microg/L, respectively, were found; for all the analytes, linearity was established over 2 orders of magnitude (r2 >0.997, n = 54). The intraday repeatability values expressed as relative standard deviations were <5.3%; a nested analysis of variance was performed to verify the influence of 3 different factors, i.e., different days, extraction procedure, and LC replicate injection, on data precision.

  6. The 1-way on-line coupled atmospheric chemistry model system MECO(n) - Part 2: On-line coupling

    NASA Astrophysics Data System (ADS)

    Kerkweg, A.; Jöckel, P.

    2011-06-01

    A new, highly flexible model system for the seamless dynamical down-scaling of meteorological and chemical processes from the global to the meso-γ scale is presented. A global model and a cascade of an arbitrary number of limited-area model instances run concurrently in the same parallel environment, in which the coarser grained instances provide the boundary data for the finer grained instances. Thus, disk-space intensive and time consuming intermediate and pre-processing steps are entirely avoided and the time interpolation errors of common off-line nesting approaches are minimised. More specifically, the regional model COSMO of the German Weather Service (DWD) is nested on-line into the atmospheric general circulation model ECHAM5 within the Modular Earth Submodel System (MESSy) framework. ECHAM5 and COSMO have previously been equipped with the MESSy infrastructure, implying that the same process formulations (MESSy submodels) are available for both models. This guarantees the highest degree of achievable consistency, between both, the meteorological and chemical conditions at the domain boundaries of the nested limited-area model, and between the process formulations on all scales. The on-line nesting of the different models is established by a client-server approach with the newly developed Multi-Model-Driver (MMD), an additional component of the MESSy infrastructure. With MMD an arbitrary number of model instances can be run concurrently within the same message passing interface (MPI) environment, the respective coarser model (either global or regional) is the server for the nested finer (regional) client model, i.e., it provides the data required to calculate the initial and boundary fields to the client model. On-line nesting means that the coupled (client-server) models exchange their data via the computer memory, in contrast to the data exchange via files on disk in common off-line nesting approaches. MMD consists of a library (Fortran95 and some parts

  7. On-Line Operating 3-D Seafloor Positioning System (1)

    NASA Astrophysics Data System (ADS)

    Eguchi, T.

    2003-12-01

    We propose a new observation system of on-line 3-D positioning which will be deployed on the sea-bottom of convergent type plate boundaries where large inter-plate seismic events occurred historically. The system has observation sites at assigned intervals along optical fiber cables. Using the several cables, crossing each other, we can construct a real-time operating network of triangular base lines. Each observing site on the cable will be equipped with two-kind high gain instruments i.e., the laser ranging and pressure gauge sensors, as well as additional apparatuses to remove the influence of temperature and salinity etc. on the data. Attenuation rate of visible rays in seawater is relatively smaller at bands of blue-color (wave length; ˜ 450nm) to yellowish green-color ( ˜ 550nm). The attenuation rate of optical signals of blue to yellow-green color in highly transparent seawater is 0.1 ˜ 0.5 dB/m. If we can utilize the high power optical laser output of the blue to yellow-green band for the positioning, the signals can reach the target receiver station with highly sensitive detector located at the distance of 10**2 m or larger. Using additional data of thermal and salinity fields etc. for compensating refractive index of laser signal ray path in clean seawater, we may attain the resolution of laser ranging at an order of 1 mm for each triangular base line with the total length of 1 ˜ 2 km. The base line consists of several secondary positioning stations with the spacing of ˜ 10**2 m. To improve the data resolution, we apply signal processing such as low-pass filtering etc. As is important, we cannot decompose the change of the base line distance data into 3-D individual components. We need another kind data, such as pure vertical coordinate of the positioning sites to resolve the 3-D components. To measure the vertical coordinate of the seafloor stations, we utilize data from the high gain pressure sensor. In the case of crystallized quartz

  8. On-line collection/concentration and determination of transition and rare-earth metals in water samples using Multi-Auto-Pret system coupled with inductively coupled plasma-atomic emission spectrometry.

    PubMed

    Katarina, Rosi Ketrin; Oshima, Mitsuko; Motomizu, Shoji

    2009-05-15

    On-line preconcentration and determination of transition and rare-earth metals in water samples was performed using a Multi-Auto-Pret system coupled with inductively coupled plasma-atomic emission spectrometry (ICP-AES). The Multi-Auto-Pret AES system proposed here consists of three Auto-Pret systems with mini-columns that can be used for the preconcentration of trace metals sequentially or simultaneously, and can reduce analysis time to one-third and running cost of argon gas and labor. A newly synthesized chelating resin, ethylenediamine-N,N,N'-triacetate-type chitosan (EDTriA-type chitosan), was employed in the Multi-Auto-Pret system for the collection of trace metals prior to their measurement by ICP-AES. The proposed resin showed very good adsorption ability for transition and rare-earth metal ions without any interference from alkali and alkaline-earth metal ions in an acidic media. For the best result, pH 5 was adopted for the collection of metal ions. Only 5 mL of samples could be used for the determination of transition metals, while 20 mL of samples was necessary for the determination of rare-earth metals. Metal ions adsorbed on the resin were eluted using 1.5 M nitric acid, and were measured by ICP-AES. The proposed method was evaluated by the analysis of SLRS-4 river water reference materials for trace metals. Good agreement with certified and reference values was obtained for most of the metals examined; it indicates that the proposed method using the newly synthesized resin could be favorably used for the determination of transition and rare-earth metals in water samples by ICP-AES.

  9. The Eclipsing Binary On-Line Atlas (EBOLA)

    NASA Astrophysics Data System (ADS)

    Bradstreet, D. H.; Steelman, D. P.; Sanders, S. J.; Hargis, J. R.

    2004-05-01

    In conjunction with the upcoming release of \\it Binary Maker 3.0, an extensive on-line database of eclipsing binaries is being made available. The purposes of the atlas are: \\begin {enumerate} Allow quick and easy access to information on published eclipsing binaries. Amass a consistent database of light and radial velocity curve solutions to aid in solving new systems. Provide invaluable querying capabilities on all of the parameters of the systems so that informative research can be quickly accomplished on a multitude of published results. Aid observers in establishing new observing programs based upon stars needing new light and/or radial velocity curves. Encourage workers to submit their published results so that others may have easy access to their work. Provide a vast but easily accessible storehouse of information on eclipsing binaries to accelerate the process of understanding analysis techniques and current work in the field. \\end {enumerate} The database will eventually consist of all published eclipsing binaries with light curve solutions. The following information and data will be supplied whenever available for each binary: original light curves in all bandpasses, original radial velocity observations, light curve parameters, RA and Dec, V-magnitudes, spectral types, color indices, periods, binary type, 3D representation of the system near quadrature, plots of the original light curves and synthetic models, plots of the radial velocity observations with theoretical models, and \\it Binary Maker 3.0 data files (parameter, light curve, radial velocity). The pertinent references for each star are also given with hyperlinks directly to the papers via the NASA Abstract website for downloading, if available. In addition the Atlas has extensive searching options so that workers can specifically search for binaries with specific characteristics. The website has more than 150 systems already uploaded. The URL for the site is http://ebola.eastern.edu/.

  10. On-line, adaptive state estimator for active noise control

    NASA Technical Reports Server (NTRS)

    Lim, Tae W.

    1994-01-01

    Dynamic characteristics of airframe structures are expected to vary as aircraft flight conditions change. Accurate knowledge of the changing dynamic characteristics is crucial to enhancing the performance of the active noise control system using feedback control. This research investigates the development of an adaptive, on-line state estimator using a neural network concept to conduct active noise control. In this research, an algorithm has been developed that can be used to estimate displacement and velocity responses at any locations on the structure from a limited number of acceleration measurements and input force information. The algorithm employs band-pass filters to extract from the measurement signal the frequency contents corresponding to a desired mode. The filtered signal is then used to train a neural network which consists of a linear neuron with three weights. The structure of the neural network is designed as simple as possible to increase the sampling frequency as much as possible. The weights obtained through neural network training are then used to construct the transfer function of a mode in z-domain and to identify modal properties of each mode. By using the identified transfer function and interpolating the mode shape obtained at sensor locations, the displacement and velocity responses are estimated with reasonable accuracy at any locations on the structure. The accuracy of the response estimates depends on the number of modes incorporated in the estimates and the number of sensors employed to conduct mode shape interpolation. Computer simulation demonstrates that the algorithm is capable of adapting to the varying dynamic characteristics of structural properties. Experimental implementation of the algorithm on a DSP (digital signal processing) board for a plate structure is underway. The algorithm is expected to reach the sampling frequency range of about 10 kHz to 20 kHz which needs to be maintained for a typical active noise control

  11. Worldwide On-line Distance Learning University Astronomy

    NASA Astrophysics Data System (ADS)

    Eyres, S. P. S.; Hassall, B. J. M.; Butchart, I.; Bromage, G. E.

    2006-08-01

    The University of Central Lancashire operates a suite of distance learning courses in Astronomy, available both on-line and via CD-ROM. The courses are available worldwide, and emphasise flexibility of study. To this end students can study anything from a single module (1/6^th of a full year at degree level) all the way up to an entire degree entirely by distance learning. Study rates vary from one to four modules each year, and students can move on to Level 2 modules (equivalent to second year level in a UK degree) before completing the full set of Level 1 modules. Over 1000 awards have been made to date. The core syllabus is Astronomy and Cosmology at Level 1, alongside skills in literature research, using computers, and basic observing. We also offer a basic history of European astronomy. At Level 2 we look at the astrophysics of the Sun, the stars, and galaxies including the Milky Way. By Level 3 students are expected to engage in a large individual project, and a collaborative investigation with other students, alongside high-level courses in cosmology, relativity, extreme states of matter and the origins of the elements, life and astronomical objects. While many students are retired people looking to exercise their brains, keen amateur amateurs or professionals with disposable incomes, and significant fraction are teachers seeking to improve their subject knowledge or high school students gaining an edge in the UK University entrance competition. Via our involvement with SALT we offer our courses to members of previously disadvantaged communities. This leads to an incredibly diverse and lively student body.

  12. Determination of vitamins D2, D3, K1 and K3 and some hydroxy metabolites of vitamin D3 in plasma using a continuous clean-up-preconcentration procedure coupled on-line with liquid chromatography-UV detection.

    PubMed

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

    1999-03-01

    A semi-automatic procedure for the continuous clean-up and concentration of several fat-soluble vitamins prior to their separation by HPLC and UV detection is reported. The procedure is based on the use of a minicolumn packed with aminopropylsilica as sorbent located prior to the chromatographic detection system. The overall process was developed and applied to the main liposoluble vitamins (A, D2, D3, E, K1, K3) and several hydroxy metabolites of vitamin D3 [25-(OH)-D3,24,25-(OH)2-D3 and 1,25-(OH)2-D3]. All the analytes were monitored at a compromise wavelength of 270 nm. Calibration graphs were constructed between 0.01 and 100 ng ml-1 for vitamin D2 and D3 and their hydroxy metabolites, between 0.1 and 100 ng ml-1 for vitamin A, K1 and K3 and between 1 and 100 ng ml-1 for vitamin E, with excellent regression coefficients (> or = 0.9901) in all cases. The precision was established at two concentration levels with acceptable RSDs in all instances (between 3.6 and 8.7%). The method was appropriate for the determination of vitamin D2, D3, K1 and K3 and the 24,25-dihydroxy and 25-hydroxy metabolites of vitamin D3 in human plasma. The method was applied to plasma samples spiked with the target analytes and the recoveries ranged between 78 and 109%.

  13. On-line Geoscience Data Resources for Today's Undergraduates

    NASA Astrophysics Data System (ADS)

    Goodwillie, A. M.; Ryan, W.; Carbotte, S.; Melkonian, A.; Coplan, J.; Arko, R.; O'Hara, S.; Ferrini, V.; Leung, A.; Bonckzowski, J.

    2008-12-01

    Broadening the experience of undergraduates can be achieved by enabling free, unrestricted and convenient access to real scientific data. With funding from the U.S. National Science Foundation, the Marine Geoscience Data System (MGDS) (http://www.marine-geo.org/) serves as the integrated data portal for various NSF-funded projects and provides free public access and preservation to a wide variety of marine and terrestrial data including rock, fluid, biology and sediment samples information, underway geophysical data and multibeam bathymetry, water column and multi-channel seismics data. Users can easily view the locations of cruise tracks, sample and station locations against a backdrop of a multi-resolution global digital elevation model. A Search For Data web page rapidly extracts data holdings from the database and can be filtered on data and device type, field program ID, investigator name, geographical and date bounds. The data access experience is boosted by the MGDS use of standardised OGC-compliant Web Services to support uniform programmatic interfaces. GeoMapApp (http://www.geomapapp.org/), a free MGDS data visualization tool, supports map-based dynamic exploration of a broad suite of geosciences data. Built-in land and marine data sets include tectonic plate boundary compilations, DSDP/ODP core logs, earthquake events, seafloor photos, and submersible dive tracks. Seamless links take users to data held by external partner repositories including PetDB, UNAVCO, IRIS and NGDC. Users can generate custom maps and grids and import their own data sets and grids. A set of short, video-style on-line tutorials familiarises users step- by-step with GeoMapApp functionality (http://www.geomapapp.org/tutorials/). Virtual Ocean (http://www.virtualocean.org/) combines the functionality of GeoMapApp with a 3-D earth browser built using the NASA WorldWind API for a powerful new data resource. MGDS education involvement (http://www.marine-geo.org/, go to Education tab

  14. Tea-industry waste activated carbon, as a novel adsorbent, for separation, preconcentration and speciation of chromium.

    PubMed

    Duran, Celal; Ozdes, Duygu; Gundogdu, Ali; Imamoglu, Mustafa; Senturk, Hasan Basri

    2011-02-28

    Activated carbon was produced from tea-industry wastes (TIWAC) and employed as a low cost and effective solid phase material for the separation, preconcentration and speciation of chromium species without using a complexing agent, prior to determination by flame atomic absorption spectrometry (FAAS). The characterization of TIWAC was performed by utilizing several techniques such as Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), and elemental analysis. The adsorption experiments were conducted in a batch adsorption technique. Under the experimental conditions, Cr(VI) adsorption amount was nearly equal to zero, however the adsorption percentage of Cr(III) was in the range of 95-100%. Therefore total chromium was determined after the reduction of Cr(VI) to Cr(III) and Cr(VI) was calculated by subtracting Cr(III) concentration from total chromium concentration. The suitable conditions for adsorption and speciation processes were evaluated in terms of pH, eluent type and volume, TIWAC concentration, adsorption and desorption contact time, etc. Adsorption capacity of TIWAC was found to be 61.0 mg g(-1). The detection limit for Cr(III) was found to be 0.27 μg L(-1) and the preconcentration factor was 50 for 200mL of sample volume. The procedure was applied to the determination and speciation of chromium in stream, tap and sea water. Also, the proposed method was applied to total chromium preconcentration in microwave digested tobacco and dried eggplant samples with satisfactory results. The method was validated by analyzing certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) and the results were in good agreement with the certified values.

  15. A versatile, refrigerant- and cryogen-free cryofocusing-thermodesorption unit for preconcentration of traces gases in air

    NASA Astrophysics Data System (ADS)

    Obersteiner, Florian; Bönisch, Harald; Keber, Timo; O'Doherty, Simon; Engel, Andreas

    2016-10-01

    We present a compact and versatile cryofocusing-thermodesorption unit, which we developed for quantitative analysis of halogenated trace gases in ambient air. Possible applications include aircraft-based in situ measurements, in situ monitoring and laboratory operation for the analysis of flask samples. Analytes are trapped on adsorptive material cooled by a Stirling cooler to low temperatures (e.g. -80 °C) and subsequently desorbed by rapid heating of the adsorptive material (e.g. +200 °C). The set-up involves neither the exchange of adsorption tubes nor any further condensation or refocusing steps. No moving parts are used that would require vacuum insulation. This allows for a simple and robust design. Reliable operation is ensured by the Stirling cooler, which neither contains a liquid refrigerant nor requires refilling a cryogen. At the same time, it allows for significantly lower adsorption temperatures compared to commonly used Peltier elements. We use gas chromatography - mass spectrometry (GC-MS) for separation and detection of the preconcentrated analytes after splitless injection. A substance boiling point range of approximately -80 to +150 °C and a substance mixing ratio range of less than 1 ppt (pmol mol-1) to more than 500 ppt in preconcentrated sample volumes of 0.1 to 10 L of ambient air is covered, depending on the application and its analytical demands. We present the instrumental design of the preconcentration unit and demonstrate capabilities and performance through the examination of analyte breakthrough during adsorption, repeatability of desorption and analyte residues in blank tests. Examples of application are taken from the analysis of flask samples collected at Mace Head Atmospheric Research Station in Ireland using our laboratory GC-MS instruments and by data obtained during a research flight with our in situ aircraft instrument GhOST-MS (Gas chromatograph for the Observation of Tracers - coupled with a Mass Spectrometer).

  16. Simple method of determination of copper, mercury and lead in potable water with preliminary pre-concentration by total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Hołyńska, B.; Ostachowicz, B.; Wȩgrzynek, D.

    1996-06-01

    Total reflection X-ray fluorescence spectrometry and chemical pre-concentration procedures have been applied for the analysis of trace concentrations of copper, mercury, and lead in drinking water samples. A simple total reflection module has been used in X-ray measurements. The elements under investigation were pre-concentrated by complexation using a mixture of carbamates followed by solvent extraction with methyl isobutyl ketone. The preconcentration procedure was tested with the use of twice-distilled water samples and samples of mineral and tap water spiked with known additions of copper, mercury, and lead. The obtained recovery and precision values are presented. The minimum detection limits for the determination of these elements in mineral and tap water samples were found to be 40 ng l -1, 60 ng l -1, and 60 ng l -1, respectively.

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

    DTIC Science & Technology

    2012-12-01

    Polanco , V. Chaurey, C.F. Chou*, N.S. Swami*, “Nano-constriction device for rapid protein pre-concentration through balance of electrokinetic forces...23, 2569. (c) Basuray, S.; Chang, H.-C. Phys. Rev. E 2007, 75, 060501. (17) Chaurey, V.; Polanco , C.; Chou, C. F.; Swami, N. S. Biomicrofluidics...Chaurey, V., Lab Chip 2009, 9, 3212–3220. [13] Chaurey, V., Polanco , C. F., Chou, C.-F., Swami, N. S. Biomicrofluidics 2012, 6, 012806. [14] Swami, N

  18. Performance of the goulden large-sample extractor in multiclass pesticide isolation and preconcentration from stream water

    USGS Publications Warehouse

    Foster, G.D.; Foreman, W.T.; Gates, Paul M.

    1991-01-01

    The reliability of the Goulden large-sample extractor in preconcentrating pesticides from water was evaluated from the recoveries of 35 pesticides amended to filtered stream waters. Recoveries greater than 90% were observed for many of the pesticides in each major chemical class, but recoveries for some of the individual pesticides varied in seemingly unpredictable ways. Corrections cannot yet be factored into liquid-liquid extraction theory to account for matrix effects, which were apparent between the two stream waters tested. The Goulden large-sample extractor appears to be well suited for rapid chemical screening applications, with quantitative analysis requiring special quality control considerations. ?? 1991 American Chemical Society.

  19. Mesoporous Silica Nanoparticles as an Adsorbent for Preconcentration and Determination of Trace Amount of Nickel in Environmental Samples by Atom Trap Flame Atomic Absorption Spectrometry

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    A rapid enrichment method based on solid-phase extraction (SPE) has been established for preconcentration and separation of trace Ni(II) ions in water samples prior to their determination by atom trap flame atomic absorption spectrometry. A column filled with bulky NH2-UVM7 was used as the novel adsorbent. Under optimal conditions, the linear range, limit of detection (LOD), and preconcentration factor (PF) were 3-92 μg/L, 0.8 μg/L, and 100, respectively. The validity of the method was checked by the standard reference material.

  20. Comparison of multiple API techniques for the simultaneous detection of microconstituents in water by on-line SPE-LC-MS/MS.

    PubMed

    Wang, Chengtao; Gardinali, Piero R

    2012-10-01

    This study described a fully automated method using on-line solid phase extraction of large volume injections coupled with high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS) to simultaneously detect a group of recalcitrant microconstituents (pharmaceuticals and personal care products, steroid hormones and sterols) in aqueous matrices. Samples (1 mL to 20 mL) were loaded to the preconcentration column at 1 mL/min, and the column was washed with 1000 μL of 25% methanol in LC/MS water to remove polar and ionic interferences before LC-MS/MS analysis. Three different atmospheric pressure ionization (API) techniques, including photoionization (APPI) with four different dopants (acetone, anisole, chlorobenzene and toluene), heated electrospray ionization (HESI) and atmospheric pressure chemical ionization (APCI), were evaluated on the basis of method detection limits (MDLs) and recoveries from different aqueous matrixes. Results indicated that APPI with toluene as dopant was the most sensitive ionization method for the majority of the analytes. When using 5 mL of sample, MDLs for pharmaceuticals and personal care products, including carbamazepine, DEET, caffeine, naproxen, acetaminophen and primidone, were between 0.3 ng/L and 15 ng/L. MDLs of hormones, including testosterone, equilenin, progesterone, equilin, 17β-estradiol, 17α-ethynylestradiol, estrone, androsterone, mestranol and estriol, were between 1.2 ng/L and 37 ng/L. The combination of APPI with dopant allowed the detection of two difficult to ionize fecal related sterols, such as coprostan-3-ol and coprostan-3-one with MDLs of 5.4 ng/L and 11 ng/L, respectively. Calculated MDLs are more than adequate for analysis of wastewater using 1 to 5 mL sample size and for surface waters using up to 20 mL sample size.

  1. Automated on-line column-switching HPLC-MS/MS method with peak focusing for the determination of nine environmental phenols in urine.

    PubMed

    Ye, Xiaoyun; Kuklenyik, Zsuzsanna; Needham, Larry L; Calafat, Antonia M

    2005-08-15

    We developed a method using isotope dilution on-line solid-phase extraction (SPE) coupled to high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for the determination in urine of nine environmental phenolic compounds: Bisphenol A; 4-tert-octylphenol; o-phenylphenol; 2,4-dichlorophenol; 2,5-dichlorophenol; 2,4,5-trichlorophenol; 2,4,6-trichlorophenol; benzophenone-3 (2-hydroxy-4-metoxybenzophenone); and triclosan (2,4,4'-trichloro-2'-hydroxyphenyl ether). A unique fully automated column-switching system, constructed using 1 autosampler, 2 HPLC pumps, and a 10-port switching valve, was designed to allow for concurrent SPE-HPLC operation with peak focusing. The phenols present in 100 microL of urine were retained and concentrated on a C18 reversed-phase size-exclusion SPE column. Then, the phenols were "back-eluted" from the SPE column and diluted through a mixing Tee before being separated from other urine matrix components using a pair of monolithic HPLC columns. The phenols were detected by negative ion-atmospheric pressure chemical ionization-MS/MS. The efficient preconcentration of the phenols by the SPE column, analyte peak focusing by the dilution, and minimal ion suppression in the LC/MS interface by the buffer-free mobile phases resulted in limits of detection as low as 0.1-0.4 ng/mL for most analytes. The method was validated on spiked pooled urine samples and on urine samples from 30 adults with no known occupational exposure to environmental phenols. The method can be used for quick and accurate analysis of large numbers of samples in epidemiologic studies for assessing the prevalence of human exposure to environmental phenols.

  2. Parts-per-trillion detection of harmala alkaloids in Undaria pinnatifida algae by on-line solid phase extraction capillary electrophoresis mass spectrometry.

    PubMed

    Tascon, Marcos; Gagliardi, Leonardo G; Benavente, Fernando

    2017-02-15

    β-carboline alkaloids of the harmala group (HAlks)-a family of compounds with pharmacologic effects-can be found at trace levels (<25 μg kg(-1) algae) in the edible invasive algae Undaria pinnatifida, known commonly as wakame. In this study, we present a simple and sensitive method to detect and quantify at low parts-per-trillion levels the six HAlks more frequently found in those plants. The method is based on on-line solid phase extraction capillary electrophoresis mass spectrometry using a C18 sorbent. First, the methodology was optimized and validated with standard solutions through the use of ultraviolet (UV) and mass spectrometry (MS) detection. Second, the optimized method for MS detection was applied to an analysis of the HAlks in U. pinnatifida extracts. The method achieved limits of detection between 2 and 77 pg mL(-1) for standards, producing an analyte preconcentration of about 1000-times in comparison to CE-MS. Some matrix effects were observed for the complex wakame extracts, especially for the most polar HAlks (harmol and harmalol), which bear aromatic hydroxyl groups. Harmine, harmaline, and norharmane were not detected in the algal extracts, whereas harmane was found at 70 pg mL(-1) (70 ng kg(-1) dry algae). The results underscored that C18-SPE-CE-MS may be considered as a powerful method to detect trace levels of alkaloids and other bioactive small molecules in complex plant extracts.

  3. On-line coupling of a microelectrode array equipped poly(dimethylsiloxane) microchip with an integrated graphite electrospray emitter for electrospray ionisation mass spectrometry.

    PubMed

    Liljegren, Gustav; Dahlin, Andreas; Zettersten, Camilla; Bergquist, Jonas; Nyholm, Leif

    2005-10-01

    A novel method for the manufacturing of microchips for on-chip combinations of electrochemistry (EC) and sheathless electrospray ionisation mass spectrometry (ESI-MS) is described. The technique, which does not require access to clean-room facilities, is based on the incorporation of an array of gold microcoil electrodes into a poly(dimethylsiloxane)(PDMS) microflow channel equipped with an integrated graphite based sheathless ESI emitter. Electrochemical measurements, which were employed to determine the electroactive area of the electrodes and to test the microchips, show that the manufacturing process was reproducible and that the important interelectrode distance in the electrochemical cell could to be adequately controlled. The EC-ESI-MS device was evaluated based on the ESI-MS detection of the oxidation products of dopamine. The results demonstrate that the present on-chip approach enables full potentiostatic control of the electrochemical cell and the attainment of very short transfer times between the electrochemical cell and the electrospray emitter. The transfer times were 0.6 and 1.2 s for flow rates of 1.0 and 0.5 microL min(-1), respectively, while the electrochemical conversion efficiency of the electrochemical cell was found to be 30% at a flow rate of 0.5 microL min(-1). To decouple the electrochemical cell from the ESI-MS high voltage and to increase the user-friendliness, the on-line electrochemistry-ESI-MS experiments were performed using a wireless Bluetooth battery-powered instrument with the chip floating at the potential induced by the ESI high voltage. The described on-chip EC-ESI-MS device can be used for fundamental electrochemical investigations as well as for applications based on the use of electrochemically controlled sample pretreatment, preconcentration and ionisation steps prior to ESI-MS.

  4. Microfluidic chip-based liquid-liquid extraction and preconcentration using a subnanoliter-droplet trapping technique.

    PubMed

    Chen, Hong; Fang, Qun; Yin, Xue-Feng; Fang, Zhao-Lun

    2005-07-01

    A robust and simple approach for microfluidic liquid-liquid (L-L) extraction at the subnanoliter-scale was developed for on-chip sample pretreatment. Organic solvent droplets of a few hundred pL were trapped within micro recesses fabricated in the channel walls of a microfabricated glass chip. L-L extraction was performed by delivering aqueous samples through the channel, with the sample stream continuously flowing adjacent to the droplets. The analytes in aqueous streams were enriched within the droplet with high preconcentration factors owing to both phase transfer and dissolution of organic solvent into the bypassing aqueous sample. An aqueous solution of butyl rhodamine B (BRB) and 1-hexanol were used, respectively, as sample and extractant to demonstrate the performance of the system. The fluorescence intensity of the dye extracted into the droplet was monitored in situ by LIF. The system proved to be an efficient means for achieving high enrichment factors of over 1000, with sample consumption of a few microL. Quantitative measurement of the extracted analyte was achieved with a linear response in the range 1 x 10(-9)-8 x 10(-7) M BRB. The precision of the measured fluorescence values for a 10(-7) M BRB standard with a 12.5 min preconcentration period was 6.6% RSD (n = 5).

  5. Determination of trace amounts of zinc by flame atomic absorption spectrometry after preconcentration with modified clinoptilolite zeolite.

    PubMed

    Hajialigol, Saeed; Taher, Mohammad Ali; Malekpour, Akbar

    2008-01-01

    Natural clinoptilolite was used as a sorbent material for solid-phase extraction and preconcentration of zinc. Clinoptilolite was first saturated with cadmium (II) and then modified with benzyldimethyltetradecylammonium chloride for increasing adsorption of 3-(2-arsenophenylazo)-4,5-dihydroxy-2,7-naphthalene disulfonic acid (neothorin). Zinc was quantitatively retained on the adsorbent by the column method in the pH range of 3.8-4.2 at a flow rate of 1 mL/min. It was eluted from the column with 5.0 mL 2 M nitric acid solution at a flow rate of 1 mL/min and determined by flame atomic absorption spectrometry at 213.9 nm. Zinc could be concentrated from a 0.03 microg/L solution with a preconcentration factor of 170. Relative standard deviation for 8 replicate determinations of 2.5 microg zinc in the final solution was 0.92%. The interference of a large number of anions and cations was studied in detail to optimize the conditions, and the method was successfully applied for determination of zinc in standard and real water samples.

  6. Preconcentration of trace arsenite and arsenate with titanium dioxide nanoparticles and subsequent determination by silver diethyldithiocarbamate spectrophotometric method.

    PubMed

    Xiao, Yabing; Ling, Jie; Qian, Shahua; Lin, Anqing; Zheng, Wenjie; Xu, Weiya; Luo, Yuxuan; Zhang, Man

    2007-09-01

    A novel method of preconcentration of trace arsenite and arsenate by using titanium dioxide nanoparticles as adsorbent was described. The concentrations of preconcentrated arsenite and arsenate were determined by a silver diethyldithiocarbamate spectrophotometric method without desorption. Batch adsorption experiments were carried out as a function of the pH, contact time, amount of titanium dioxide nanoparticles, and solution volume. In the pH range 5 to 6, adsorption rates of arsenite and arsenate were higher than 98%. The calibration coefficient was 0.9991, and the linear range was 0 to 100 microg/L. The developed method was precise, with the relative standard deviation <5% at concentration level of 10 microg/L, with a detection limit (3sigma, n=6) of 0.44 microg/L. The accuracy of the method for total arsenic was validated by standard reference materials (SRM 3103a) (National Institute of Standards and Technology, Gaithersburg, Maryland). The method was also applied to the analysis of arsenite and arsenate in natural water samples to verify the accuracy. The recovery values remained in a narrow range, from 95 to 103%.

  7. Selective preconcentration of uranyl ion by silica gel phases modified with chelating compounds as inorganic polymeric ion exchangers.

    PubMed

    Mahmoud, Mohamed E; Kenawy, Ibrahim M M; Soliman, Ezzat M; Hafez, Medhat A; Akl, Magda A A; Lashein, Rabab R A

    2008-03-01

    Four chemically modified chelating silica gel phases (I - IV) with ion exchange groups were tested for their potential capability to selectively bind, extract and preconcentrate uranyl ions (UO(2)(2+)) from different aqueous solutions as well as ore samples. Factors affecting such determination processes were studied and optimized. These included the pH of the contact solution, the mass of the silica gel phase extractant, the stirring time during the application of a static technique and the eluent concentration for desorption of the surface-bound uranyl ion and interfering anions and cations. All these factors were evaluated on the basis of determinations of the distribution coefficient value (K(d)) and the percent recovery (R%). Percent recovery values of 91% for silica phase (II) and 93% for silica phase (IV) were identified in the optimum conditions. The proposed preconcentration method was further applied to uranium ore samples as well as granite samples. The determined percentage and ppm values are in good agreement with the standard assigned ones. The structure of the synthesized silica gel phases (I - IV) and their uranyl bound complexes were identified and characterized by means of infrared analysis, thermal analysis (TGA) and potentiometric titration.

  8. Optimization and application of homogeneous liquid-liquid extraction in preconcentration of copper (II) in a ternary solvent system.

    PubMed

    Farajzadeh, Mir Ali; Bahram, Morteza; Zorita, Saioa; Mehr, Behzad Ghorbani

    2009-01-30

    In this study a homogeneous liquid-liquid extraction based on the Ph-dependent phase-separation process was investigated using a ternary solvent system (water-acetic acid-chloroform) for the preconcentration of Cu(2+) ions. 8-Hydroxy quinoline was used as the chelating agent prior to its extraction. Flame atomic absorption spectrophotometry using acetylene-air flame was used for the quantitation of analyte after preconcentration. The effect of various experimental parameters in extraction step was investigated using two optimization methods, one variable at a time and central composite design. The experimental design was done at five levels of operating parameters. Nearly the same optimized results were obtained using both methods: sample size, 5 mL; volume of NaOH 10 M, 2 mL; chloroform volume, 300 microL; 8-hydroxy quinoline concentration more than 0.01 M and salt amount did not affect the extraction significantly. Under the optimum conditions the calibration graph was linear over the range 10-2000 microg L(-1). The relative standard deviation was 7.6% for six repeated determinations (C = 500 microg L(-1)). Furthermore, the limit of detection (S/N=3) and limit of quantification (S/N=10) of the method were obtained as 1.74 and 6 microg L(-1), respectively.

  9. Preconcentration and Speciation of Trace Elements and Trace-Element Analogues of Radionuclides by Neutron Activation Analysis

    SciTech Connect

    Chatt, A.

    1999-11-14

    We have developed a number of preconcentration neutron activation analysis (PNAA) methods in our laboratory for the determination of trace elements in a variety of complex sample matrices. We developed a number of cocrystallization and coprecipitation methods for the determination of trace elements in water samples. We developed several methods for the determination of I in foods and diets. We have developed a number of PNAA methods in our laboratory We determined As and Sb in geological materials and natural waters by coprecipitation with Se and Au in silicate rocks and ores by coprecipitation with Te followed by NAA. We developed an indirect NAA method for the determination of B in leachates of borosilicate glass. We have been interested in studying the speciation of Am, Tc, and Np in simulated vitrified groundwater leachates of high-level wastes under oxid and anoxic conditions using a number of techniques. We then used PNAA methods to study speciation of trace-element analogues of radionuclides. We have been able to apply biochemical techniques and NAA for the separation, preconcentration, and characterization of metalloprotein and protein-bound trace-element species in subcellular fractions of bovine kidneys. Lately, we have concentrated our efforts to develop chemical and biochemical methods in conjunction with NAA, NMR, and MS for the separation and identification of extractable organohalogens (EOX) in tissues of beluga whales, cod, and northern pink shrimp

  10. Rapid and direct determination of glyphosate, glufosinate, and aminophosphonic acid by online preconcentration CE with contactless conductivity detection.

    PubMed

    See, Hong Heng; Hauser, Peter C; Ibrahim, Wan Aini Wan; Sanagi, Mohd Marsin

    2010-01-01

    Rapid and direct online preconcentration followed by CE with capacitively coupled contactless conductivity detection (CE-C(4)D) is evaluated as a new approach for the determination of glyphosate, glufosinate (GLUF), and aminophosphonic acid (AMPA) in drinking water. Two online preconcentration techniques, namely large volume sample stacking without polarity switching and field-enhanced sample injection, coupled with CE-C(4)D were successfully developed and optimized. Under optimized conditions, LODs in the range of 0.01-0.1 microM (1.7-11.1 microg/L) and sensitivity enhancements of 48- to 53-fold were achieved with the large volume sample stacking-CE-C(4)D method. By performing the field-enhanced sample injection-CE-C(4)D procedure, excellent LODs down to 0.0005-0.02 microM (0.1-2.2 microg/L) as well as sensitivity enhancements of up to 245- to 1002-fold were obtained. Both techniques showed satisfactory reproducibility with RSDs of peak height of better than 10%. The newly established approaches were successfully applied to the analysis of glyphosate, glufosinate, and aminophosphonic acid in spiked tap drinking water.

  11. Trace level determination of beryllium in natural and flavored mineral waters after pre-concentration using activated carbon.

    PubMed

    Kılınç, Ersin; Bakırdere, Sezgin; Yaman, Mehmet

    2011-04-01

    The concentrations of beryllium (Be) in natural and flavored mineral water samples were determined by flame atomic absorption spectrophotometer (FAAS) after pre-concentration based on the complexation of Be(+2) with a mixture of acetylacetone (pentane-2,4-dione) plus morin (3,5,7,2',4'-pentaoxyflavone) and adsorption on activated carbon. The adsorbed complex was eluted with 1.5 ml of 2.0 M HNO(3) and evaporated to dryness. After adding 1.5 ml of 2 M HNO(3) and centrifuging, Be in acid solution was determined by FAAS. To remove a number of metals present in water, EDTA was used as a chelating agent. Beryllium in mineral water samples was pre-concentrated by 500-fold, taking 750 ml as initial sample and 1.5 ml as the final volume. The relative standard deviations were sufficiently low for practical purposes and recoveries were up to 85%. Spiking experiments were performed in real samples to establish accuracy and recoveries. The limits of detection and quantification were 0.01 and 0.03 ng ml(-1), respectively. Twenty samples were analyzed for their beryllium content using optimum parameters. The highest concentration of beryllium was found to be 0.94 ± 0.15 ng ml(-1) in a natural mineral water, while beryllium was not detected in five samples.

  12. Electromembrane extraction-preconcentration followed by microvolume UV-Vis spectrophotometric determination of mercury in water and fish samples.

    PubMed

    Fashi, Armin; Yaftian, Mohammad Reza; Zamani, Abbasali

    2017-04-15

    Electromembrane extraction technique combined with microvolume UV-Vis spectrophotometric detection was proposed for the preconcentration-determination of mercury in water and fish samples. The optimized conditions for preconcentration step were: the applied potential 70V, bis(2-ethylhexyl) phosphate as the extractant in 1-octanol 2% v/v, extraction time 10min, stirring rate 700rpm, acceptor and donor solutions pH 3 and 7, respectively. The linear range was found to be 2.3-950.0μgL(-1) and 40-9500μgkg(-1) in water and fish samples, with corresponding detection limits of 0.7μgL(-1) and 12μgkg(-1), respectively. The method showed satisfactory repeatability and reproducibility (CV<6%). Methodological validation was performed by using cold vapor atomic absorption spectroscopy. The proposed method provided a rapid, sensitive and accurate method which is applicable for routine analysis of total mercury contents in water and fish samples.

  13. In-capillary preconcentration of pirimicarb and carbendazim with a monolithic polymeric sorbent prior to separation by CZE.

    PubMed

    Rodríguez-Gonzalo, Encarnación; Domínguez-Alvarez, Javier; Ruano-Miguel, Luis; Carabias-Martínez, Rita

    2008-10-01

    CZE was assayed for the separation of carbamate pesticides susceptible to protonation (Pirimicarb, Carbendazim). Different electrophoretic media with high organic contents were explored, adequate separation and resolution being achieved when a BGE based on ACN with acetic acid in the presence of SDS as an ionic additive was used. With a view to increasing the sensitivity of the method, an in-capillary SPE step prior to the electrophoretic separation was developed. We employed a monolithic polymer formed in situ within the capillary as a medium for analyte retention. The synthesized monolithic bed exhibited high porosity and allowed samples to be loaded at flow rates of about 65 microL/min by applying a pressure of 12 bar. A 5-cm length of monolithic sorbent was used to preconcentrate the target analytes from aqueous samples. The analytes retained were eluted from the polymeric phase directly in the separation capillary with the same electrophoretic medium used for their further separation by CZE. For a 15-min preconcentration time, the in-line SPE-CZE approach proposed here permitted the determination of these pesticides in drinking water at a concentration level of 0.1 microg/L, as demanded by current EU legislation.

  14. An integrated microfluidic chip for immunocapture, preconcentration and separation of β-amyloid peptides

    PubMed Central

    Mohamadi, Reza M.; Svobodova, Zuzana; Bilkova, Zuzana; Otto, Markus; Taverna, Myriam; Descroix, Stephanie; Viovy, Jean-Louis

    2015-01-01

    We present an integrated microfluidic chip for detection of β-amyloid (Aβ) peptides. Aβ peptides are major biomarkers for the diagnosis of Alzheimer's disease (AD) in its early stages. This microfluidic device consists of three main parts: (1) An immunocapture microcolumn based on self-assembled magnetic beads coated with antibodies specific to Aβ peptides, (2) a nano-porous membrane made of photopolymerized hydrogel for preconcentration, and (3) a microchip electrophoresis (MCE) channel with fluorescent detection. Sub-milliliter sample volume is either mixed off-chip with antibody coated magnetic beads and injected into the device or is injected into an already self-assembled column of magnetic beads in the microchannel. The captured peptides on the beads are then electrokinetically eluted and re-concentrated onto the nano-membrane in a few nano-liters. By integrating the nano-membrane, total assay time was reduced and also off-chip re-concentration or buffer exchange steps were not needed. Finally, the concentrated peptides in the chip are separated by electrophoresis in a polymer-based matrix. The device was applied to the capture and MCE analysis of differently truncated peptides Aβ (1–37, 1–39, 1–40, and 1–42) and was able to detect as low as 25 ng of synthetic Aβ peptides spiked in undiluted cerebrospinal fluid (CSF). The device was also tested with CSF samples from healthy donors. CSF samples were fluorescently labelled and pre-mixed with the magnetic beads and injected into the device. The results indicated that Aβ1-40, an important biomarker for distinguishing patients with frontotemporal lobe dementia from controls and AD patients, was detectable. Although the sensitivity of this device is not yet enough to detect all Aβ subtypes in CSF, this is the first report on an integrated or semi-integrated device for capturing and analyzing of differently truncated Aβ peptides. The method is less demanding and faster than the conventional

  15. A Survey of Five On-line Retrieval Systems. Final Report.

    ERIC Educational Resources Information Center

    Welch, Noreen O.

    This report is a survey of five on-line retrieval systems that, with one exception, have been used to demonstrate on-line access to the recently developed Committee on Scientific and Technical Information (COSATI) inventory of government sponsored work now in progress in the area of information sciences and technology. The report was prepared to…

  16. The Anatomy of Program Design for an On-Line Business Management Course

    ERIC Educational Resources Information Center

    Barger, Bonita

    2008-01-01

    How does one design an on-line course to bridge theory and practice? How can the feedback of on-going stakeholder (student and administration) be incorporated into the design process to enhance quality? This paper presents the theoretical underpinning of designing an on-line management course recognized as best practice for a "well organized…

  17. The Impact of Cognitive Style on Social Networks in On-Line Discussions

    ERIC Educational Resources Information Center

    Jablokow, Kathryn; Vercellone-Smith, Pamela

    2011-01-01

    With the rise of e-Learning in engineering education, understanding the impact of individual differences on the ways students communicate and collaborate on-line has become increasingly important. The research described here investigates the influence of cognitive style on the interactions within student social networks in an on-line learning…

  18. Report on On-Line Trial Test for Fourth-Grade Students -- May 2009

    ERIC Educational Resources Information Center

    Verbic, Srdjan; Tomic, Boris; Kartal, Vesna

    2010-01-01

    On-line trial testing for fourth-grade students was an exploratory study realized as a part of the project "Developing annual test of students' achievement in Nature & Society" realized by Institute for Education Quality and Evaluation. Main ideas of the study were to explore possibilities for on-line testing at national level in…

  19. International On-Line Reciprocal Peer Tutoring to Promote Modern Language Development in Primary Schools

    ERIC Educational Resources Information Center

    Thurston, Allen; Duran, David; Cunningham, Erika; Blanch, Silvia; Topping, Keith

    2009-01-01

    The paper reports data from an on-line peer tutoring project. In the project 78, 9-12-year-old students from Scotland and Catalonia peer tutored each other in English and Spanish via a managed on-line environment. Significant gains in first language (Catalonian pupils) modern language (Scottish pupils) and attitudes towards modern languages (both…

  20. The Radical Model--A Painless Way To Teach On-Line.

    ERIC Educational Resources Information Center

    Romm, C.; Taylor, W.

    The information technology/information systems (IT/IS) education sector needs to come up with creative ways of thinking about on-line education. In this paper, the major themes in the literature on on-line education to date are highlighted with a view to identifying issues that are either missing or under-emphasized. Next, the "radical model of…

  1. An On-Line Electronics Graphics Symbol Set for the PLATO IV System.

    ERIC Educational Resources Information Center

    McClintock, Peggy A.; Kimberlin, Donald A.

    An electronics graphic symbol set for on-line construction of electrical and electronics schematic diagrams is described. Specific procedures involving off-line and on-line activities are presented for the development and entry of schematic diagrams utilizing a stored set of symbols. An example of the commands and coding required for the…

  2. Careers On-Line: Career Networks for University Students with Disabilities.

    ERIC Educational Resources Information Center

    Aune, Betty; Stockdill, Stacy; Johnson, Donna; Lomas, Devora; Gaipa, Beth; Lorsung, Tina

    This final report describes Careers On-Line, a model demonstration project that is designed, using the Internet, to provide students with disabilities, career service providers, and employers with up-to-date information on career development, employment, and disabilities. Careers On-Line developed databases on job and internship postings, adaptive…

  3. On-Line Literature Search and Full Articles in the NASA ADS

    NASA Technical Reports Server (NTRS)

    Eichhorn, G.; Accomazzi, A.; Grant, C. S.; Kurtz, M. J.; Murray, S. S.

    2001-01-01

    The ADS provides free world-wide on-line access to over 2.2 million abstracts and over 1 million scanned pages of the astronomical and planetary literature plus over 4 million links to other relevant on-line information at http://ads.harvard.edu. Additional information is contained in the original extended abstract.

  4. High School Open On-Line Courses (HOOC): A Case Study from Italy

    ERIC Educational Resources Information Center

    Canessa, Enrique; Pisani, Armando

    2013-01-01

    The first implementation of complete high school, open on-line courses (HOOC) aiming to support the training and basic scientific knowledge of young students from the Liceo Ginnasio Dante Alighieri in Gorizia, Italy, is discussed. Using the open source and automated recording system openEyA, HOOC give a student the opportunity to watch on-line, at…

  5. Students Reflecting on Test Performance and Feedback: An On-Line Approach

    ERIC Educational Resources Information Center

    Fyfe, Georgina; Fyfe, Sue; Meyer, Jan; Ziman, Mel; Sanders, Kathy; Hill, Julie

    2014-01-01

    Undergraduate students accessing on-line tests in Human Biology in three Western Australian universities were asked to complete an on-line post-test reflective survey about their perceptions of their test performance in light of automated feedback. The survey allowed pre-determined choices and comment text boxes relating to students' perceptions…

  6. Developmental and Individual Differences in Children's On-Line Representations of Dynamic Social Events.

    ERIC Educational Resources Information Center

    Milch-Reich, Shoulamit; Campbell, Susan B.; Pelham, William E., Jr.; Connelly, Lynda M.; Geva, Diklah

    1999-01-01

    Compared the "on-line" (real time, ongoing internal representation) understanding of ongoing social events of boys with and without attention-deficit hyperactivity disorder (ADHD). Found that younger children and those with ADHD showed less integrated on-line representations, accounting for poor recall and reasoning. (Author/KB)

  7. Improvement plans for the RHIC/AGS on-line model environments

    SciTech Connect

    Brown,K.A.; Ahrens, L.; Beebe-Wang, J.; Morris, J.; Nemesure, S.; Robert-Demolaize, G.; Satogata, T.; Schoefer, V.; Tepikian, S.

    2009-08-31

    The on-line models for Relativistic Ion Collider (RHIC) and the RHIC pre-injectors (the AGS and the AGS Booster) can be thought of as containing our best collective knowledge of these accelerators. As we improve these on-line models we are building the framework to have a sophisticated model-based controls system. Currently the RHIC on-line model is an integral part of the controls system, providing the interface for tune control, chromaticity control, and non-linear chromaticity control. What we discuss in this paper is our vision of the future of the on-line model environment for RHIC and the RHIC preinjectors. Although these on-line models are primarily used as Courant-Snyder parameter calculators using live machine settings, we envision expanding these environments to encompass many other problem domains.

  8. Intelligent identification of wear mechanism via on-line ferrograph images

    NASA Astrophysics Data System (ADS)

    Wu, Tonghai; Peng, Yeping; Sheng, Chenxing; Wu, Jiaoyi

    2014-03-01

    Condition based maintenance(CBM) issues a new challenge of real-time monitoring for machine health maintenance. Wear state monitoring becomes the bottle-neck of CBM due to the lack of on-line information acquiring means. The wear mechanism judgment with characteristic wear debris has been widely adopted in off-line wear analysis; however, on-line wear mechanism characterization remains a big problem. In this paper, the wear mechanism identification via on-line ferrograph images is studied. To obtain isolated wear debris in an on-line ferrograph image, the deposition mechanism of wear debris in on-line ferrograph sensor is studied. The study result shows wear debris chain is the main morphology due to local magnetic field around the deposited wear debris. Accordingly, an improved sampling route for on-line wear debris deposition is designed with focus on the self-adjustment deposition time. As a result, isolated wear debris can be obtained in an on-line image, which facilitates the feature extraction of characteristic wear debris. By referring to the knowledge of analytical ferrograph, four dimensionless morphological features, including equivalent dimension, length-width ratio, shape factor, and contour fractal dimension of characteristic wear debris are extracted for distinguishing four typical wear mechanisms including normal, cutting, fatigue, and severe sliding wear. Furthermore, a feed-forward neural network is adopted to construct an automatic wear mechanism identification model. By training with the samples from analytical ferrograph, the model might identify some typical characteristic wear debris in an on-line ferrograph image. This paper performs a meaningful exploratory for on-line wear mechanism analysis, and the obtained results will provide a feasible way for on-line wear state monitoring.

  9. FEDIX on-line information service: Design, develop, test, and implement an on-line research and education information service. Annual status report, September 1992--August 1993

    SciTech Connect

    Rodman, J.A.

    1993-08-01

    Federal Information Exchange, Inc. (FIE) is a diversified information services company that is recognized as the major electronic link between the higher education community and the Federal government in the field of research administration. FIE provides a range of information related services to the government, academic and private sectors, including database management, software development and technical support. FEDIX is the on-line information service designed, developed and implemented by FIE to accomplish the following objectives: (1). Broaden the participation of the education community in Federal research and education programs by providing free and unrestricted on-line access to information from all participating Federal agencies; and (2). Provide the education community with on-line access to a single keyword-searchable system for research and educational funding opportunities at the participating Federal agencies.

  10. Preparation of xylenol orange functionalized silica gel as a selective solid phase extractor and its application for preconcentration--separation of mercury from waters.

    PubMed

    Fan, Jing; Wu, Chunlai; Wei, Yafang; Peng, Chuanyun; Peng, Pingan

    2007-06-25

    A new selective solid phase extractor was prepared from silica gel modified with xylenol orange (SGMXO). The solid phase extractor is stable in 6molL(-1) HCl, common organic solvents, and pH 1.0-9.0 buffer solutions. In the batch experiments, Hg(II) can be adsorbed on SGMXO at pH 1.0 with 90.0% retention, whereas the retention of other common coexisting metal ions such as Cd(II), Pb(II), Cu(II), Ni(II), Co(II), Mn(II), Zn(II), and Fe(III) is less than 4.1%.. The adsorption equilibration for Hg(II) was achieved within 3min. At optimum conditions, the adsorption capacity of the extractor is 18.26micromolg(-1) of dry modified silica gel, and the preconcentration factor is as high as 333. The recovery is still higher than 95% for the preconcentration of 10ngmL(-1) Hg(II). The new solid phase extractor has been used for the preconcentration of low level of Hg(II) in surface water, tap water in chemistry laboratory and student's dormitory and a simulated sea water samples, recoveries of 98.2-100.6% were obtained. It is showed that low level of Hg(II) can be effectively preconcentrated by this new selective solid phase extractor.

  11. Preconcentration of low levels of americium and plutonium from waste waters by synthetic water-soluble metal-binding polymers with ultrafiltration

    SciTech Connect

    Smith, B.F.; Gibson, R.R.; Jarvinen, G.D.; Robison, T.W.; Schroeder, N.C.; Stalnaker, N.D.

    1997-12-31

    A preconcentration approach to assist in the measurement of low levels of americium and plutonium in waste waters has been developed based on the concept of using water-soluble metal-binding polymers in combination with ultrafiltration. The method has been optimized to give over 90% recovery and accountability from actual waste water.

  12. Synthesis and application of a new functionalized resin for use in an on-line, solid phase extraction system for the determination of trace elements in waters and reference cereal materials by flame atomic absorption spectrometry.

    PubMed

    Karadaş, Cennet; Turhan, Onur; Kara, Derya

    2013-11-15

    The synthesis and characterization of the resin Amberlite XAD-4 functionalized with 2,6-pyridinedicarboxaldehyde and its application in an on-line system for the preconcentration of cadmium, cobalt, copper, lead and manganese prior to determination using flame atomic absorption spectrometry (FAAS) is proposed. Metal ions retained on the modified resin were eluted using 1.0 mol L(-1) HNO3 solution and aspirated directly to the nebulizer-burner system of a FAAS instrument using a flow injection system. Detection limits (3σ) were determined to be 0.13 μg L(-1) for Cd, 0.29 μg L(-1) for Cu, 0.23 μg L(-1) for Mn, 0.58 μg L(-1) for Co and 2.19 μg L(-1) for Pb using a 10 mL of water sample loading volume. The limits of detection would be 100 times higher with units of μg kg(-1) for the solid samples in which their dilution ratios as (volume/weight) were 100. Enrichment factors ranged from 23.6 to 28.9 (for Co and Mn, respectively). The proposed method was successfully applied to determination of the analytes in natural water samples and certified reference materials.

  13. A new coprecipitation methodology with lutetium hydroxide for preconcentration of heavy metal ions in herbal plant samples.

    PubMed

    Soylak, Mustafa; Murat, Ipek

    2014-01-01

    A new coprecipitation methodology that used lutetium hydroxide as a precipitant for Cu(II), Pb(II), Mn(II), Co(II), Cd(II), Fe(III), and Ni(II) ions in herbal plant and water samples for analysis by atomic absorption spectrometry has been investigated. The parameters such as pH, amount of lutetium, and volume of aqueous sample were optimized for the recovery of these seven metals. The effects of concomitant ions on the separation-preconcentration of analytes were also checked. The validation of the procedure was checked with addition recovery tests and analysis of Standard Reference Material 1570a-Trace Elements in Spinach Leaves and TMDA-70 fortified lake water Certified Reference Material. The LODs for analyte ions were in the range of 1.7-7.2 microg/L. The application of the present procedure was successfully performed for the analysis of analyte contents of herbal plant samples from Turkey.

  14. Analysis of trace metals in water by inductively coupled plasma emission spectrometry using sodium dibenzyldithiocarbamate for preconcentration

    USGS Publications Warehouse

    Smith, C.L.; Motooka, J.M.; Willson, W.R.

    1984-01-01

    Since concentrations of trace elements in most natural waters seldom exceed the ??g/L level, analysis of trace elements in natural waters by inductively coupled plasma emission spectrometry (ICP) requires a preconcentration procedure. The elements Ag, Bi, Cd, Co, Cu, Fe, Mo, Ni, Pb, Sn, V, W, and Zn were separated and concentrated from 500 mL of water by coprecipitating them with sodium dibenzyldithiocarbamate (NaDBDTC) using nickel or silver as a carrier. The precipitated trace elements were collected on a membrane filter, redissolved from the filter with hot nitric and hydrochloric acids, and analyzed using ICP. Recoveries for all the trace elements except tungsten exceeded 80%. Coprecipitation of trace elements with NaDBDTC eliminated the use of difficult-to-inject organic solvents, and NaDBDTC coprecipitated a wider array of trace elements than ammoniumpyrrolidinedithiocarbamate (APDC), another commonly used coprecipitate.

  15. Ionic liquids for simultaneous preconcentration of some lanthanoids using dispersive liquid-liquid microextraction technique in uranium dioxide powder.

    PubMed

    Mallah, Mohammad H; Shemirani, Farzaneh; Maragheh, Mohammad G

    2009-03-15

    Ionic liquids in a dispersive liquid-liquid microextraction technique were used for determination of lanthanoids such as samarium, europium, gadolinium, and dysprosium in uranium dioxide powder. In this process, an appropriate mixture of extraction solvent and disperser is rapidly injected into an aqueous sample containing samarium, europium, gadolinium, and dysprosium ions complexes with 1-hydroxy-2, 5-pyrrolidinedione, and consequently a cloudy solution is formed. It consists of fine droplets of extraction solventwhich are dispersed entirely into the aqueous phase. After centrifugation of this solution, the whole enriched phase was determined by inductively coupled plasma optical emission spectrometry. In the present work, the preconcentration factor, limit of detection, and relative standard deviation were investigated for samarium, europium, gadolinium, and dysprosium in uranium dioxide powder.

  16. On chip preconcentration and fluorescence labeling of model proteins using monolithic columns: device fabrication, optimization, and automation

    PubMed Central

    Yang, Rui; Pagaduan, Jayson V.; Yu, Ming

    2015-01-01

    Microfluidic systems are developed with monolithic columns for preconcentration and on-chip labeling of model proteins. Monoliths are prepared in microchannels via photopolymerization, and the properties of monoliths are optimized by varying the composition and concentration of monomers to improve flow and extraction. On-chip labeling of proteins is achieved by driving solutions through the monolith using voltage and incubating fluorescent dye with protein retained in the monolith. Subsequently, the labeled proteins are eluted by applying voltages to reservoirs on the microdevice and then detected by laser-induced fluorescence. Monoliths prepared from octyl methacrylate show the best combination of protein retention while still allowing unattached fluorescent label to be eluted in a separate fraction with 50% acetonitrile. Finally, automated on-chip extraction and fluorescence labeling of a model protein is successfully demonstrated. This work provides facile sample pretreatment, and therefore offers promising potential for future integrated bioanalysis microchips. PMID:25012353

  17. Determination of trace level bromate and perchlorate in drinking water by ion chromatography with an evaporative preconcentration technique.

    PubMed

    Liu, Yongjian; Mou, Shifen; Heberling, Shawn

    2002-05-17

    A simple sample preconcentration technique employing microwave-based evaporation for the determination of trace level bromate and perchlorate in drinking water with ion chromatography is presented. With a hydrophilic anion-exchange column and a sodium hydroxide eluent in linear gradient, bromate and perchlorate can be determined in one injection within 35 min. Prior to ion chromatographic analysis, the drinking water sample was treated with an OnGuard-Ag cartridge to remove the superfluous chloride and concentrated 20-fold using a PTFE beaker in a domestic microwave oven for 15 min. The recoveries of the anions ranged from 94.6% for NO2- to 105.2% for F-. The detection limits for bromate, perchlorate, iodate and chlorate were 0.1, 0.2, 0.1 and 0.2 microg/l, respectively. The developed method is applicable for the quantitation of bromate and perchlorate in drinking water samples.

  18. Study of Halitosis-Substance Sensing at Low Concentration Using an Electrochemical Sensor Array Combined with a Preconcentrator

    NASA Astrophysics Data System (ADS)

    Sasaya, Yosuke; Nakamoto, Takamichi

    A method for quantitative detection and discrimination of volatile sulfur compounds (VSCs) using an electrochemical sensor array combined with a preconcentrator was proposed. Halitosis is due to VSCs produced by bacterial metabolism inside the oral cavity. An organoleptic test is typically performed by a dental clinician for the assessment of halitosis, although it is a subjective test. Thus, an objective evaluation of halitosis is required. In this study, it was possible to discriminate among the VSCs such as hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and dimethyl sulfide ((CH3)2S) over the range of 200ppb to 1000ppb. Moreover, mixture of two VSC vapors (H2S and CH3SH) at various mixing ratios were measured. The results indicated that the sensor responses to mixed samples satisfied the linear superposition. The mixture compositions of VSCs were almost correctly obtained from the sensor responses using partial least squares (PLS) regression analysis.

  19. A new polymeric adsorbent for screening and pre-concentration of organotin compounds in sediments and seawater samples

    NASA Astrophysics Data System (ADS)

    Puri, Bal Krishan; Muñoz-Olivas, Riansares; Cámara, Carmen

    2004-02-01

    A new adsorbent based on the imprinting technique with high retention capacity and pre-concentration factor has been synthesized and tested for retention of inorganic and organotin compounds [tributyltinchloride (TBT), dibutyltindichloride (DBT), monobutylytintrichloride (MBT) and triphenyltinchoride (TPhT)]. The polymerization has been carried out in the presence of TBT, the target organotin compound of this work. These compounds can be quantitatively retained on this adsorbent over a wide pH range and after elution these compounds are determined by graphite furnace atomic absorption spectrometry (GFAAS). Only organotin compounds are eluted from the adsorbent with 0.1 M hydrochloric acid (HCl) in methanol (MeOH) solution whereas inorganic tin is eluted later on with a suitable complexing agent such as citric acid. Linearity is obtained in the concentration range 0.1-4 ng (5-200 μg l -1) for each organotin compound with a correlation coefficient not less than 0.994 and relative standard deviation <5% even for complex samples such as sediments and seawater samples. The detection limit has been found to be 30 ng l -1. Various parameters related to determination, pre-concentration and GFAAS conditions have been optimized. The screening method proposed has been applied to the determination of organotin in natural sediments and seawater samples. The recovery is between 82 and 90% for TBT, DBT and TPhT and 50-55% for MBT in the case of sediment samples, while it is 97-103% for all the organotin compounds in seawater samples. The method has been conveniently validated using a standard sediment reference material.

  20. Trace element analysis of aqueous samples by laser-induced breakdown spectroscopy based on pre-concentration of electrospray

    NASA Astrophysics Data System (ADS)

    Ni, Kai; Lei, Yu; Yu, Quan; Li, Jianan; Qian, Xiang; Wang, Xiaohao

    2015-08-01

    Laser-induced breakdown spectroscopy (LIBS) is characterized as a powerful tool in in-situ online analysis with its fast and multiple detecting abilities. But in the area of detecting trace sample in aqueous solution of low concentration, the turbulence, scattering, absorbance and cooling effect of liquid medium limits its performance. Traditional method includes liquid jet, liquid-solid transformation and pre-concentration on other medium, yet the procedure of sample preparation is complicated and time consuming. In this work, we propose a new method to achieve pre-concentration, in which filter paper and electro-spray ionization (ESI) are used. In our experiment, we choose MnSO4 as sample. The surface of filter paper is sprayed with MnSO4 aqueous solution of different concentration by an ESI. The pulsed laser is focused on the surface of filter paper and the plasma is formed in the focusing area. Through an optical fiber the spectrum of plasma is detected by a spectrometer. The ESI system, pulses generator system and the UI on PC are home-made. The spectra lines of Mn at 257.6nm, 259.4nm and 260.6nm are analyzed. Results show that the limit of detection at 257.6nm is sub-ppb and the R2 of calibration curve is more than 0.93. Compared with traditional method, like soak and drip processing, our method can increase the concentration of the sample by simply expanding spraying time, achieving a higher signal-to-noise ratio (SNR) and a lower limit of detection (LOD). In addition, the consumption of sample solution is as low as several hundred μl in each detection.

  1. Reversed-phase dispersive liquid-liquid microextraction with central composite design optimization for preconcentration and HPLC determination of oleuropein.

    PubMed

    Hashemi, Payman; Raeisi, Fatemeh; Ghiasvand, Ali Reza; Rahimi, Akram

    2010-03-15

    A reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) method was developed for the preconcentration and direct HPLC determination of oleuropein in olive's processing wastewater (OPW) and olive leaves extracts. In conventional DLLME, the sedimented phase is a micro-drop of a chlorinated organic solvent that is not compatible with RP-HPLC. Therefore, solvent evaporation and reconstitution with an appropriate solvent is often required. In RP-DLLME, this problem was overcome by overturning the solvent polarity in the ordinary DLLME and replacing the organic solvent with water. A central composite chemometrics design was used for multivariate optimization of the effects of five different parameters influencing the extraction efficiency of the method. In the optimized conditions, a mixture of 1.4 mL of an ethyl acetate extract of sample and 40 microL water (pH 5.0) was rapidly injected into 5.3 mL of cyclohexane. After centrifugation of the formed cloudy mixture, a micro-drop of the aqueous phase was sedimented at the conical bottom of the centrifuge tube. This phase, that contained the preconcentrated and partially purified analyte, was directly injected into an RP-HPLC column for analysis. A mean extraction recovery of 102.5 (+/-4.5) % with enrichment factors exceeding 38, was obtained for five replicated analysis. The detection limit of the method (3 sigma) for OE was 0.02 microg L(-1) for OPW and 2 x 10(-3) mg kg(-1) for olive leaves samples. The results showed that, RP-DLLME is a promising technique which is quick, easily operated and can be directly coupled to HPLC.

  2. Quantification of Alkyl Nitrates in Ambient Air by Thermal Dissociation Cavity Ring-Down Spectroscopy with Preconcentration

    NASA Astrophysics Data System (ADS)

    Ye, C. Z.; Osthoff, H. D.; Taha, Y. M.; Pak, J. K.; Saowapon, M. T.

    2015-12-01

    Alkyl nitrates (AN, molecular formula RONO2) play a crucial role in the troposphere as temporary reservoirs of nitrogen oxides (NOx =NO +NO2) and by acting as chain terminators in the photochemical production of ozone. Mixing ratios of AN in ambient air are commonly quantified by gas chromatography with electron capture or mass spectrometric detection (GC-ECD or GC-MS) coupled to purge-and-trap preconcentration, usually on Tenax sorbent, to improve the detection limits. The analysis, however, is quite laborious as there are many alkyl nitrates that are low in individual abundance (often less than 1 parts-per-trillion by volume, pptv) and that exhibit different instrumental response factors. An alternative method is to determine alkyl nitrates as a sum (ΣAN) by thermal dissociation (TD) to a common fragment (NO2), which can then be quantified with a uniform response factor by optical absorption, for example by cavity ring-down spectroscopy (CRDS). However, the determination of ΣAN by TD-CRDS is hampered by its relatively high detection limits (several 100 pptv) and secondary chemistry following TD that results in both negative and positive interferences and depends on the composition of the ambient air sampled. In this work, a TD-CRDS equipped with a Tenax preconcentration unit is described. Matrix effects are minimized by desorbing the samples from the Tenax in a background of nitrogen. The performance of the instrument, in particular the recovery from the Tenax sorbent, was evaluated by sampling laboratory-generated mixtures of alkyl and peroxyacyl nitrates. Field data from a coastal site collected during the Ozone-depleting reactions in a coastal atmosphere (ORCA) campaign, which took place at the Amphitrite Point Observatory in Ucluelet, BC, from July 6 - 31, 2015, are presented. Advantages and disadvantages of the new method are discussed.

  3. Solid-phase extraction of polar pesticides from environmental water samples on graphitized carbon and Empore-activated carbon disks and on-line coupling to octadecyl-bonded silica analytical columns.

    PubMed

    Slobodník, J; Oztezkizan, O; Lingeman, H; Brinkman, U A

    1996-10-25

    The suitability of Empore-activated carbon disks (EACD), Envi-Carb graphitized carbon black (GCB) and CPP-50 graphitized carbon for the trace enrichment of polar pesticides from water samples was studied by means of off-line and on-line solid-phase extraction (SPE). In the off-line procedure, 0.5-2 l samples spiked with a test mixture of oxamyl, methomyl and aldicarb sulfoxide were enriched on EnviCarb SPE cartridges or 47 mm diameter EACD and eluted with dichloromethane-methanol. After evaporation, a sample was injected onto a C18-bonded silica column and analysed by liquid chromatography with ultraviolet (LC-UV) detection. EACD performed better than EnviCarb cartridges in terms of breakthrough volumes (> 2 l for all test analytes), reproducibility (R.S.D. of recoveries, 4-8%, n = 3) and sampling speed (100 ml/min); detection limits in drinking water were 0.05-0.16 microgram/l. In the on-line experiments, 4.6 mm diameter pieces cut from original EACD and stacked onto each other in a 9 mm long precolumn, and EnviCarb and CPP-50 packed in 10 x 2.0 mm I.D. precolumn, were tested, and 50-200 ml spiked water samples were preconcentrated. Because of the peak broadening caused by the strong sorption of the analytes on carbon, the carbon-packed precolumns were eluted by a separate stream of 0.1 ml/min acetonitrile which was mixed with the gradient LC eluent in front of the C18 analytical column. The final on-line procedure was also applied for the less polar propoxur, carbaryl and methiocarb. EnviCarb could not be used due to its poor pressure resistance. CPP-50 provided less peak broadening than EACD: peak widths were 0.1-0.3 min and R.S.D. of peak heights 4-14% (n = 3). In terms of analyte trapping efficiency on-line SPE-LC-UV with a CPP-50 precolumn also showed better performance than when Bondesil C18/OH or polymeric PLRP-S was used, but chromatographic resolution was similar. With the CPP-50-based system, detection limits of the test compounds were 0.05-1 microgram

  4. Using a strengths model to build an on-line nursing education program.

    PubMed

    Wieck, K Lynn; Alfred, Danita; Haas, Barbara K; Yarbrough, Susan

    2014-01-01

    The on-line environment is the new frontier for academia struggling to define its place in the evolving economy. A concern is how to engage students who maximize their on-line experience and graduate in a timely manner. A strengths model was used as the basis for development of an on-line doctoral nursing program. Upon entering the program, students were given a strengths assessment that focused both students and faculty on the positive attributes students were bringing to their doctoral studies. A positive feedback methodology using on-line discussions in each course was used to support the identified strengths. The optimal picture of a successful entering doctoral student appears to be a person whose top five strengths are learner, achiever, input, connectedness and responsibility. A strengths model promotes a positive learning environment and supports a teacher-learner dynamic where faculty members are encouraged to focus on the students' strengths rather than their challenges.

  5. ON-LINE TOOLS FOR PROPER VERTICAL POSITIONING OF VERTICAL SAMPLING INTERVALS DURING SITE ASSESSMENT

    EPA Science Inventory

    This presentation presents on-line tools for proper vertical positioning of vertical sampling intervals during site assessment. Proper vertical sample interval selection is critical for generate data on the vertical distribution of contamination. Without vertical delineation, th...

  6. Integration of On-Line and Off-Line Diagnostic Algorithms for Aircraft Engine Health Management

    NASA Technical Reports Server (NTRS)

    Kobayashi, Takahisa; Simon, Donald L.

    2007-01-01

    This paper investigates the integration of on-line and off-line diagnostic algorithms for aircraft gas turbine engines. The on-line diagnostic algorithm is designed for in-flight fault detection. It continuously monitors engine outputs for anomalous signatures induced by faults. The off-line diagnostic algorithm is designed to track engine health degradation over the lifetime of an engine. It estimates engine health degradation periodically over the course of the engine s life. The estimate generated by the off-line algorithm is used to update the on-line algorithm. Through this integration, the on-line algorithm becomes aware of engine health degradation, and its effectiveness to detect faults can be maintained while the engine continues to degrade. The benefit of this integration is investigated in a simulation environment using a nonlinear engine model.

  7. On-Line Serials Control System in a Large Biomedical Library: (1) Description of the System

    ERIC Educational Resources Information Center

    Fayollat, James

    1972-01-01

    An on-line serials control system with particular emphasis on storage and maintenance concepts is described. The system allows real-time display and updating of all elements of the file. (6 references) (Author)

  8. Education and Training for On-Line Use of Data Bases

    ERIC Educational Resources Information Center

    Williams, Martha E.

    1977-01-01

    This paper discusses vehicles for education and training, tools and techniques for promotion, and details the information requirements of the processors, service managers, searchers, and end users of on-line data bases. (Author/KP)

  9. On Line Spectrophotometric Measurement of Uranium and Nitrate in H Canyon

    SciTech Connect

    Lascola, R.J.

    2002-10-15

    This report describes the on-line instrumentation developed by the Analytical Development Section of Savannah River Technology Center in support of Highly Enriched Uranium Blend Down processing in H Canyon.

  10. On-line chemical composition analyzer development. Status report, February 1, 1993--April 30, 1993

    SciTech Connect

    Garrison, A.A.

    1993-06-01

    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)

  11. Trace analysis of three antihistamines in human urine by on-line single drop liquid-liquid-liquid microextraction coupled to sweeping micellar electrokinetic chromatography and its application to pharmacokinetic study.

    PubMed

    Gao, Wenhua; Chen, Yunsheng; Chen, Gaopan; Xi, Jing; Chen, Yaowen; Yang, Jianying; Xu, Ning

    2012-09-01

    A rapid and efficient dual preconcentration method of on-line single drop liquid-liquid-liquid microextraction (SD-LLLME) coupled to sweeping micellar electrokinetic chromatography (MEKC) was developed for trace analysis of three antihistamines (mizolastine, chlorpheniramine and pheniramine) in human urine. Three analytes were firstly extracted from donor phase (4 mL urine sample) adjusted to alkaline condition (0.5 M NaOH). The unionized analytes were subsequently extracted into a drop of n-octanol layered over the urine sample, and then into a microdrop of acceptor phase (100 mM H(3)PO(4)) suspended from a capillary inlet. The enriched acceptor phase was on-line injected into capillary with a height difference and then analyzed directly by sweeping MEKC. Good linear relationships were obtained for all analytes in a range of 6.25 × 10(-6) to 2.5 × 10(-4)g/L with correlation coefficients (r) higher than 0.987. The proposed method achieved limits of detections (LOD) varied from 1.2 × 10(-7) to 9.5 × 10(-7)g/L based on a signal-to-noise of 3 (S/N=3) with 751- to 1372-fold increases in detection sensitivity for analytes, and it was successfully applied to the pharmacokinetic study of three antihistamines in human urine after an oral administration. The results demonstrated that this method was a promising combination for the rapid trace analysis of antihistamines in human urine with the advantages of operation simplicity, high enrichment factor and little solvent consumption.

  12. Metal-organic framework MIL-101 as sorbent based on double-pumps controlled on-line solid-phase extraction coupled with high-performance liquid chromatography for the determination of flavonoids in environmental water samples.

    PubMed

    Liu, Yue; Hu, Jia; Li, Yan; Li, Xiao-Shuang; Wang, Zhong-Liang

    2016-10-01

    A novel method with high sensitivity for the rapid determination of chrysin, apigenin and luteolin in environment water samples was developed by double-pumps controlled on-line solid-phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC). In the developed technique, metal organic framework MIL-101 was synthesized and applied as a sorbent for SPE. The as-synthesized MIL-101 was characterized by scanning electron microscope, X-ray diffraction spectrometry, thermal gravimetric analysis and micropore physisorption analysis. The MIL-101 behaved as a fast kinetics in the adsorption of chrysin, apigenin and luteolin. On-line SPE of chrysin, apigenin and luteolin was processed by loading a sample solution at a flow rate of 1.0 mL/min for 10 min. The extracted analytes were subsequently eluted into a ZORBAX Bonus-RP analytical column (25 cm long × 4.6 mm i.d.) for HPLC separation under isocratic condition with a mobile phase (MeOH: ACN: 0.02 M H3 PO4 = 35:35:30) at a flow rate of 1.0 mL/min. Experimental conditions, including ionic strength, sample pH, sample loading rates, sample loading time and desorption analytes time, were further optimized to obtain efficient preconcentration and high-precision determination of the analytes mentioned above. The method achieved the merits of simplicity, rapidity, sensitivity, wide linear range and high sample throughput. The possible mechanism for the adsorption of flavonoids on MIL-101 was proposed. The developed method has been applied to determine trace chrysin, apigenin and luteolin in a variety of environmental water samples.

  13. Analysis and occurrence of selected medium to highly polar pesticides in groundwater of Catalonia (NE Spain): An approach based on on-line solid phase extraction-liquid chromatography-electrospray-tandem mass spectrometry detection

    NASA Astrophysics Data System (ADS)

    Postigo, Cristina; López de Alda, Maria José; Barceló, Damià; Ginebreda, Antoni; Garrido, Teresa; Fraile, Josep

    2010-03-01

    SummaryThe present work describes an automated methodology based on on-line solid phase extraction-liquid chromatography-electrospray-tandem mass spectrometry (on-line SPE-LC-ESI-MS/MS) for the determination of 22 medium to highly polar pesticides in groundwater, and its application to the analysis of 133 samples collected from different aquifers of Catalonia (NE Spain), in areas where agricultural practice is significant. Sample preconcentration was performed by passing 5 mL of the sample through PLRPs cartridges (for analysis of 16 pesticides measured in the positive ionization mode) and through Hysphere-Resin GP cartridges (for analysis of six pesticides measured in the negative ionization mode). Further LC-MS/MS determination was performed in the selected reaction monitoring (SRM) mode, by recording two SRM transitions per compound, thus obtaining four identification points. The methodology developed allows the determination of the target compounds at the pg or low ng L -1 level with satisfactory precision (relative standard deviations lower than 16%) and accuracy (recovery percentages higher than 75%) and is well suited for routine monitoring. Its application to various groundwater samples from Catalonia has revealed simazine, diuron and atrazine (present in more than 70% of the samples) as the most ubiquitous compounds. Approximately 16% of the samples investigated had individual pesticides levels above 100 ng L -1 and 7% presented total pesticides levels above 500 ng L -1. Concentrations higher than 100 ng L -1 were found for all triazines studied but cyanazine, the phenylureas diuron, linuron and chlortoluron, the target chloroacetanilides alachlor and metolachlor, and the organophosphate dimethoate in a few samples. Three and eight out of the 16 investigated groundwater bodies presented total pesticide levels exceeding the EU quality standards in terms of individual and total pesticide concentrations, 100 and 500 ng L -1, respectively.

  14. On line high dose static position monitoring by ionization chamber detector for industrial gamma irradiators.

    PubMed

    Rodrigues, Ary A; Vieira, Jose M; Hamada, Margarida M

    2010-01-01

    A 1 cm(3) cylindrical ionization chamber was developed to measure high doses on line during the sample irradiation in static position, in a (60)Co industrial plant. The developed ionization chamber showed to be suitable for use as a dosimeter on line. A good linearity of the detector was found between the dose and the accumulated charge, independently of the different dose rates caused by absorbing materials.

  15. Nonlinear Feedback Control for Rapid, On-Line Trajectory Optimization of Reentry Vehicles (PREPRINT)

    DTIC Science & Technology

    2005-12-01

    feedback without using an inner-loop tracking controller. The original concept dates back to the early 1990’s, when Pesch discussed off- line and on- line...approach is not mature enough for general optimal control problems. Although this paper 3 does not provide the “mathematical justification” that Pesch ...Guidance, Navigation, and Control Conference, AIAA Paper No. 2001-4429, Aug 2001. 14. Pesch , H.J., “Off-Line and On-Line Computation of Optimal

  16. First structures on RyantoRainbow Line. Hframe structure on Line 1 ...

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

    First structures on Ryan-to-Rainbow Line. H-frame structure on Line 1 (right) has historic porcelain suspension insulators and H-frame structure on Line 2 (center) has two historic porcelain insulators and one modern non-ceramic insulator. View to north - Ryan Hydroelectric Facility, Ryan-to-Rainbow 100 kV Transmission Line, West bank of Missouri River, northeast of Great Falls, Great Falls, Cascade County, MT

  17. The effects of stigmatizing discourse on the quality of on-line relationships.

    PubMed

    Wildermuth, Susan M

    2004-02-01

    Previous research has demonstrated that a societal stigma exists against individuals involved in on-line relationships. This study was designed to examine the impact that stigmatizing discourse from off-line family and friends has on the overall quality of such relationships. Participants in this study consisted of 159 on-line relationship partners who completed a web-based survey. The survey asked participants to recall messages that they had received about their online relationship from their off-line family and friends, and to fill out a questionnaire addressing their level of stigma consciousness and their perceptions of the quality of their on-line relationship. Trained coders then rated the messages from family and friends for levels of disapproval, severity, and explicitness. Results demonstrated that more severe, disapproving, and explicit messages from off-line family and friends correlated with higher levels of stigma consciousness on the part of the on-line relationship participant. Additionally, relationship participants who experienced more stigma consciousness were less satisfied with the overall quality of their on-line relationships. The theoretical and methodological implications of these results for on-line relationship are discussed.

  18. On-Line Wavelength Calibration of Pulsed Laser for CO2 Differential Absorption LIDAR

    NASA Astrophysics Data System (ADS)

    Xiang, Chengzhi; Ma, Xin; Han, Ge; Liang, Ailin; Gong, Wei

    2016-06-01

    Differential absorption lidar (DIAL) remote sensing is a promising technology for atmospheric CO2 detection. However, stringent wavelength accuracy and stability are required in DIAL system. Accurate on-line wavelength calibration is a crucial procedure for retrieving atmospheric CO2 concentration using the DIAL, particularly when pulsed lasers are adopted in the system. Large fluctuations in the intensities of a pulsed laser pose a great challenge for accurate on-line wavelength calibration. In this paper, a wavelength calibration strategy based on multi-wavelength scanning (MWS) was proposed for accurate on-line wavelength calibration of a pulsed laser for CO2 detection. The MWS conducted segmented sampling across the CO2 absorption line with appropriate number of points and range of widths by using a tunable laser. Complete absorption line of CO2 can be obtained through a curve fitting. Then, the on-line wavelength can be easily found at the peak of the absorption line. Furthermore, another algorithm called the energy matching was introduced in the MWS to eliminate the backlash error of tunable lasers during the process of on-line wavelength calibration. Finally, a series of tests was conducted to elevate the calibration precision of MWS. Analysis of tests demonstrated that the MWS proposed in this paper could calibrate the on-line wavelength of pulsed laser accurately and steadily.

  19. On-Line Retrieval System Design; Part V of Scientific Report No. ISR-18, Information Storage and Retrieval...

    ERIC Educational Resources Information Center

    Cornell Univ., Ithaca, NY. Dept. of Computer Science.

    On-line retrieval system design is discussed in the two papers which make up Part Five of this report on Salton's Magical Automatic Retriever of Texts (SMART) project report. The first paper: "A Prototype On-Line Document Retrieval System" by D. Williamson and R. Williamson outlines a design for a SMART on-line document retrieval system…

  20. Extraction and preconcentration of selenium from aqueous solutions and its determination in water and hair samples by atomic-absorption spectrophotometry.

    PubMed

    Ejaz, M; Qureshi, M A

    1987-03-01

    Several organic solvents, including benzene, xylene, toluene, nitrobenzene, chloroform, carbon tetrachloride, chlorobenzene and high molecular-weight pyridines such as 4-(5-nonyl)pyridine, 2-hexyl-pyridine and benzylpyridine have been investigated as components of systems for the extraction and preconcentration of selenium from nitric acid solutions containing iodide. The results are discussed in terms of choice of reagents and the acid and iodide concentrations, and of several other parameters affecting the extraction. The utility of the method for separation of selenium from aqueous solution has been evaluated. The method has been used for preconcentration of trace levels of selenium from water and hair samples for determination by atomic-absorption spectrophotometry.

  1. Copper(II)-8-hydroxquinoline coprecipitation system for preconcentration and separation of cobalt(II) and manganese(II) in real samples.

    PubMed

    Soylak, Mustafa; Kaya, Betul; Tuzen, Mustafa

    2007-08-25

    A separation-preconcentration procedure based on the coprecipitation of cobalt(II) and manganese(II) ions with copper(II)-8-hydroxquinoline system has been developed. The analytical parameters including pH, amount of copper(II) as carrier element, amount of 8-hydroxquinoline, sample volume, etc., was investigated for the quantitative recoveries of Co(II) and Mn(II). No interferic effects were observed from the concomitant ions which are present in real samples. The detection limits for analyte ions by three sigma criteria were 0.86microgL(-1) for cobalt and 0.98microgL(-1) for manganese. The validation of the presented preconcentration procedure was performed by the analysis of NIST SRM 2711 Montana soil and GBW 07605 Tea certified reference materials. The procedure presented was applied to the analyte contents of real samples including natural waters and some food samples with successfully analytical results.

  2. Simultaneous determination of trace heavy metals in ambient aerosols by inductively coupled plasma atomic emission spectrometry after pre-concentration with sodium diethyldithiocarbamate.

    PubMed

    Talebi, S M; Malekiha, M

    2008-07-01

    The simultaneous determination of heavy metals associated with airborne particulate matter in the atmosphere of the city Isfahan (Iran) was performed by inductively coupled plasma atomic emission spectrometry (ICP-AES) after pre-concentration with sodium diethyldithiocarbamate. The preconcentration procedure developed found instrumental to determine the trace heavy metals associated with ambient aerosols collected at a short sampling period or collected from rural areas where the concentrations of these metals are much less than those in urban areas. Several samples were analyzed by both flame atomic absorption spectrometry (FAAS) as a conventional method and the proposed method. The results obtained by the two methods were found in good agreement. The method was applied to the determination of atmospheric level of heavy metals in rural area and also for study of variation in levels of heavy metals in urban atmosphere during the days and nights.

  3. iGC2: an architecture for micro gas chromatographs utilizing integrated bi-directional pumps and multi-stage preconcentrators

    NASA Astrophysics Data System (ADS)

    Qin, Yutao; Gianchandani, Yogesh B.

    2014-06-01

    This paper reports an integrated micro gas chromatography (µGC) architecture which utilizes a bi-directional micropump. Four integral components--the bi-directional Knudsen pump (KP2), a two-stage preconcentrator-focuser (PCF2), a separation column, and a gas detector--are integrated in a 4.3 cm3 stack, forming a serial flow path. All four components are fabricated using the same three-mask process. Compared to the conventional approach used with multi-stage preconcentrators, in which valves are used to reverse flow between the sampling phase and the separation phase, this µGC architecture reduces the overall complexity. In this architecture, the vapors being sampled are drawn through the detector and column before reaching the PCF2. The microsystem operation is experimentally validated by quantitative analyses of benzene, toluene, and xylene vapors ranging in concentration from 43-1167 mg m-3.

  4. Research of on-line monitoring method for insulation condition of power transformer bushing

    NASA Astrophysics Data System (ADS)

    Xia, Jiuyun; Qian, Zheng; Yu, Hao; Yao, Junda

    2016-01-01

    The power transformer is the key equipment of the power system; its insulation condition will directly influence the security and reliability of the power system. Thus, the on-line monitoring of power transformer is urgently required in order to guarantee the normal operation of the power system. Moreover, the dielectric loss factor is a significant parameter reflecting the condition of transformer bushing, so the on-line measurement of dielectric loss factor is really important. In this paper, the phase-to-phase comparison method is selected as the on-line monitoring method based on the overall analysis and discussion of the existing on-line monitoring methods. At first, the harmonic analysis method is utilized to calculate the dielectric loss of each phase of the three-phase transformer bushing, and then the differences of dielectric loss between every two phases are calculated and analyzed. So the insulation condition of each bushing could be achieved based on the careful analysis of different phase-to-phase dielectric loss. The simulation results of phase-to-phase comparison method are carried out in this paper, and the validity is verified. At last, this method is utilized in an actual equipment of on-line monitoring.

  5. Preconcentration of trace elements from water samples on a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO2 nanoparticles for determination by ICP-AES.

    PubMed

    Baytak, Sitki; Zereen, Fahmida; Arslan, Zikri

    2011-04-15

    A trace element preconcentration procedure is described utilizing a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO(2) nanoparticles for determination of Cr, Cu, Fe, Mn, Ni and Zn from water samples by inductively coupled plasma atomic emission spectrometry. The elements were quantitatively retained on the column between pH 6 and 8. Elution was made with 5% (v/v) HNO(3) solution. Recoveries ranged from 98 ± 2 (Cr) to 100 ± 4 (Zn) for preconcentration of 50 mL multielement solution (50 μg L(-1)). The column made up of 100mg sorbent (yeast immobilized TiO(2) NP) offers a capacity to preconcentrate up to 500 mL of sample solution to achieve an enrichment factor of 250 with 2 mL of 5% (v/v) HNO(3) eluent. The detection limits obtained from preconcentration of 50 mL blank solutions (5%, v/v, HNO(3), n=11) were 0.17, 0.45, 0.25, 0.15, 0.33 and 0.10 μg L(-1) for Cr, Cu, Fe, Mn, Ni and Zn, respectively. Relative standard deviation (RSD) for five replicate analyses was better than 5%. The retention of the elements was not affected from up to 500 μg L(-1) Na(+) and K(+) (as chlorides), 100 μg L(-1) Ca(2+) (as nitrate) and 50 μg L(-1) Mg(2+) (as sulfate). The method was validated by analysis of freshwater standard reference material (SRM 1643e) and applied to the determination of the elements from tap water and lake water samples.

  6. Nickel (II) Preconcentration and Speciation Analysis During Transport from Aqueous Solutions Using a Hollow-fiber Permeation Liquid Membrane (HFPLM) Device

    PubMed Central

    Bautista-Flores, Ana Nelly; de San Miguel, Eduardo Rodríguez; de Gyves, Josefina; Jönsson, Jan Åke

    2011-01-01

    Nickel (II) preconcentration and speciation analysis using a hollow fiber supported liquid membrane (HFSLM) device was studied. A counterflow of protons coupled to complexation with formate provided the driving force of the process, while Kelex 100 was employed as carrier. The influence of variables related to module configuration (acceptor pH and carrier concentration) and to the sample properties (donor pH) on the preconcentration factor, E, was simultaneously studied and optimized using a 3 factor Doehlert matrix response surface methodology. The effect of metal concentration was studied as well. Preconcentration factors as high as 4240 were observed depending on the values of the different variables. The effects of the presence of inorganic anions (NO2−, SO42−, Cl−, NO3−, CO32−, CN−) and dissolved organic matter (DOM) in the form of humic acids were additionally considered in order to carry out a speciation analysis study. Nickel preconcentration was observed to be independent of both effects, except when cyanide was present in the donor phase. A characterization of the transport regime was performed through the analysis of the dependence of E on the temperature. E increases with the increase in temperature according to the equation E(K) = −8617.3 + 30.5T with an activation energy of 56.7 kJ mol−1 suggesting a kinetic-controlled regime. Sample depletion ranged from 12 to 1.2% depending on the volume of the donor phase (100 to 1000 mL, respectively). PMID:24957733

  7. A smart sensor system for trace organic vapor detection using a temperature-controlled array of surface acoustic wave vapor sensors, automated preconcentrator tubes, and pattern recognition

    SciTech Connect

    Grate, J.W.; Rose-Pehrsson, S.L.; Klusty, M.; Wohltjen, H.

    1993-05-01

    A smart sensor system for the detection, of toxic organophosphorus and toxic organosulfur vapors at trace concentrations has been designed, fabricated, and tested against a wide variety of vapor challenges. The key features of the system are: An array of four surface acoustic wave (SAW) vapor sensors, temperature control of the vapor sensors, the use of pattern recognition to analyze the sensor data, and an automated sampling system including thermally-desorbed preconcentrator tubes (PCTs).

  8. Ring-oven based preconcentration technique for microanalysis: simultaneous determination of Na, Fe, and Cu in fuel ethanol by laser induced breakdown spectroscopy.

    PubMed

    Cortez, Juliana; Pasquini, Celio

    2013-02-05

    The ring-oven technique, originally applied for classical qualitative analysis in the years 1950s to 1970s, is revisited to be used in a simple though highly efficient and green procedure for analyte preconcentration prior to its determination by the microanalytical techniques presently available. The proposed preconcentration technique is based on the dropwise delivery of a small volume of sample to a filter paper substrate, assisted by a flow-injection-like system. The filter paper is maintained in a small circular heated oven (the ring oven). Drops of the sample solution diffuse by capillarity from the center to a circular area of the paper substrate. After the total sample volume has been delivered, a ring with a sharp (c.a. 350 μm) circular contour, of about 2.0 cm diameter, is formed on the paper to contain most of the analytes originally present in the sample volume. Preconcentration coefficients of the analyte can reach 250-fold (on a m/m basis) for a sample volume as small as 600 μL. The proposed system and procedure have been evaluated to concentrate Na, Fe, and Cu in fuel ethanol, followed by simultaneous direct determination of these species in the ring contour, employing the microanalytical technique of laser induced breakdown spectroscopy (LIBS). Detection limits of 0.7, 0.4, and 0.3 μg mL(-1) and mean recoveries of (109 ± 13)%, (92 ± 18)%, and (98 ± 12)%, for Na, Fe, and Cu, respectively, were obtained in fuel ethanol. It is possible to anticipate the application of the technique, coupled to modern microanalytical and multianalyte techniques, to several analytical problems requiring analyte preconcentration and/or sample stabilization.

  9. Preconcentration of trace elements from water samples on a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO2 nanoparticles for determination by ICP-AES

    PubMed Central

    Baytak, Sıtkı; Zereen, Fahmida; Arslan, Zikri

    2011-01-01

    A trace element preconcentration procedure is described utilizing a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO2 nanoparticles for determination of Cr, Cu, Fe, Mn, Ni and Zn from water samples by inductively coupled plasma atomic emission spectrometry. The elements were quantitatively retained on the column between pH 6 and 8. Elution was made with 5% v/v HNO3 solution. Recoveries ranged from 98 ± 2 (Cr) to 100 ± 4 (Zn) for preconcentration of 50 mL multielement solution (50 µg L−1). The column made up of 100 mg sorbent (yeast immobilized TiO2 NP) offers a capacity to preconcentrate up to 500 mL of sample solution to achieve an enrichment factor of 250 with 2 mL of 5% v/v HNO3 eluent. The detection limits obtained from preconcentration of 50 mL blank solutions (5% v/v HNO3, n =11) were 0.17, 0.45, 0.25, 0.15, 0.33 and 0.10 µg L−1 for Cr, Cu, Fe, Mn, Ni and Zn, respectively. Relative standard deviation (RSD) for five replicate analyses was better than 5%. The retention of the elements was not affected from up to 500 µg mL−1 Na+ and K+ (as chlorides), 100 µg mL−1 Ca2+ (as nitrate) and 50 µg mL−1 Mg2+ (as sulfate). The method was validated by analysis of freshwater standard reference material (SRM 1643e) and applied to the determination of the elements from tap water and lake water samples. PMID:21376951

  10. Determination of trace amounts of Pd(II) ions in water and road dust samples by flame atomic absorption spectrometry after preconcentration on modified organo nanoclay.

    PubMed

    Afzali, Daryoush; Mostafavi, Al; Afzali, Zahra

    2010-01-01

    This paper describes the application of organo nanoclay, an easily prepared and stable solid sorbent, to the preconcentration of trace amounts of palladium ions in aqueous solution. The organo nanoclay was prepared by adding tetradecyldimethylbenzylamonium chloride onto montmorillonite, which was then modified with 1-(2-pyridylazo)-2-naphthol. The modified nanoclay was used as a solid sorbent for separation and preconcentration of trace amounts of Pd(II) ions, and a simple, sensitive, and economical method was developed for determination of trace amounts of palladium by flame atomic absorption spectrometry. The sorption of Pd(II) ions was quantitative in the pH range of 1.5-5.0, whereas quantitative desorption occurred with 5.0 mL of a mixture containing 1.0 M thiourea and 1.0 M HCl. The RSD of the method was +/- 2.1% (n = 10; concn = 0.5 microg/mL), and the LOD (3sigma(bl); sigma = SD and bl = blank) was 0.1 ng/mL. The calibration curve was linear for concentrations of 0.5-8.0 microg/mL in the initial solution, and the preconcentration factor was 140. The maximum capacity of the sorbent was 2.4 mg Pd(II)/g modified organo nanoclay. The influences of the experimental parameters, including sample pH, eluant volume, eluant type, sample volume, and interfering ions, on the recoveries of the palladium ion were investigated. The proposed method was applied to the preconcentration and determination of palladium in different samples.

  11. Use of short chain alkyl imidazolium ionic liquids for on-line stacking and sweeping of methotrexate, flinic acid and folic acid: their application to biological fluids.

    PubMed

    Abd El-Hady, Deia; Albishri, Hassan M; Rengarajan, Rajesh; Wätzig, Hermann

    2014-07-01

    Methotrexate (MTX) is widely used for the treatment of many types of cancer. Folinic acid (FNA) and folic acid (FA) were usually simultaneously supplemented with MTX to reduce the side effects of a folate deficiency. This study, for the first time, included on-line sample preconcentration by stacking and sweeping techniques under reduced or enhanced electric conductivity in the sample region using short chain alkyl imidazolium ionic liquids (ILs) as micelle forming agents for analyte focusing. Both analyte focusing by micelle collapse (AFMC) and sweeping-MEKC had been investigated for the comparison of their effectiveness to examine simultaneously MTX, FNA and FA in plasma and urine under physiological conditions. In sweeping-MEKC, the sample solution without micelles was hydrodynamically injected as a long plug into a fused-silica capillary pre-filled with phosphate buffer containing 3.0 mol/L of 1-butyl-3-methylimidazolium bromide (BMIMBr). Using AFMC, the analytes were prepared in BMIMBr micellar matrix and hydrodynamically injected into the phosphate buffer without IL micelles. The conductivity ratio between BGE and sample (γ, BGE/sample) was optimized to be 3.0 in sweeping-MEKC and 0.33 in AFMC resulting the adequate separation of analytes within 4.0 min. To reduce the possibility of BMIMBr adsorption, an appropriate rinsing protocol was used. The limits of detection were calculated as 0.1 ng/mL MTX, 0.05 ng/mL FNA and 0.05 ng/mL FA by sweeping-MEKC and 0.5 ng/mL MTX, 0.3 ng/mL FNA and 0.3 ng/mL FA by AFMC. The accuracy was tested by recovery in plasma and urine matrices giving values ranging between 90 and 110%. Both stacking and sweeping by BMIMBr could be successfully used for the rapid, selective and sensitive determination of pharmaceuticals in complex matrices due to its fascinating properties, including high conductivity, good thermal stability and ability to form different types of interactions by electrostatic, hydrophobic, hydrogen bonding and

  12. The use of a polymer inclusion membrane as a sorbent for online preconcentration in the flow injection determination of thiocyanate impurity in ammonium sulfate fertilizer.

    PubMed

    Ohshima, Takumi; Kagaya, Shigehiro; Gemmei-Ide, Makoto; Cattrall, Robert W; Kolev, Spas D

    2014-11-01

    A polymer inclusion membrane (PIM) is used for the first time as a sorbent in the construction of a preconcentration column to enhance the sensitivity in flow injection analysis (FIA). The PIM-coated column is readily prepared by coating the PIM containing poly(vinyl chloride), Aliquat 336, and 1-tetradecanol onto glass beads packed in a glass tube. The determination of trace amounts of thiocyanate in ammonium sulfate fertilizer demonstrates the potential of the proposed PIM-coated column in FIA. Thiocyanate standards or samples of relatively large volume (e.g. up to 2000 µL) are injected into a nitrate carrier stream. The sample zone passes through the proposed preconcentration column where thiocyanate is concentrated in a smaller volume of a carrier solution thus resulting in up to 7.4 fold increase in sensitivity. Thiocyanate is detected spectrophotometrically after its reaction with Fe(III) downstream of the preconcentration column. The limits of detection of thiocyanate in the absence and presence of 20 g L(-1) ammonium sulfate (S/N=2) are 0.014 and 0.024 mg L(-1), respectively. Thiocyanate was successfully determined in several samples of ammonium sulfate fertilizer.

  13. Determination of trace heavy metals in soil and sediments by atomic spectrometry following preconcentration with Schiff bases on Amberlite XAD-4.

    PubMed

    Kara, Derya; Fisher, Andrew; Hill, Steve J

    2009-06-15

    A matrix separation and analyte preconcentration system using Amberlite XAD copolymer resins functionalized by Schiff base reactions coupled with atomic spectrometry has been developed. Three different functionalized Amberlite XAD resins were synthesized using 4-phenylthiosemicarbazide, 2,3-dihydroxybenzaldehyde and 2-thiophenecarboxaldehyde as reagents. These resins could be used to preconcentrate transition and other trace heavy metal analytes from nitric acid digests of soil and sediment samples. Analyte retention was shown to work well at pH 6.0. After treatment of the digests with sodium fluoride and buffering to pH 6, samples that contain extremely large concentrations of iron were analysed for trace analytes without the excess iron overloading the capacity of the resin. The analytes Cd, Co, Cu, Ni and Pb were preconcentrated from acid extracts of certified soil/sediment samples and then eluted with 0.1M HNO(3) directly to the detection system. Flame atomic absorption spectrometry was used as a means of detection during the studies. The efficiency of the chelating resin and the accuracy of the proposed method were evaluated by the analysis of soil (SO-2) and sediment (LGC 6157 and MESS-3) certified reference materials.

  14. 3D-printed microfluidic magnetic preconcentrator for the detection of bacterial pathogen using an ATP luminometer and antibody-conjugated magnetic nanoparticles.

    PubMed

    Park, Chanyong; Lee, Jinyeop; Kim, Yonghee; Kim, Jaewon; Lee, Jinkee; Park, Sungsu

    2017-01-01

    Various types of microfluidic systems have been developed to detect bacterial pathogens. However, most of these require enrichment steps that take at least several hours when detecting bacteria that are present with a low number of cells and, in addition, fabrication requires complicated assembly steps. In this study, we report the development of 3D microfluidic magnetic preconcentrator (3DμFMP) made of plastic via 3D printing without the need for any assembly. 3DμFMP could selectively preconcentrate enterohemorrhagic Escherichia coli O157:H7 in 100mL by a factor of 700 within 1h using antibody-conjugated magnetic nanoparticles (Ab-MNPs). With the combined use of an ATP luminometer, as low as 10 E. coli O157:H7 CFU (colony forming unit)/mL could be detected in blood. These results demonstrate the feasibility of 3DμFMP as a preconcentrator to improve the detection limit of existing bacterial detection systems.

  15. Determination of trace aluminum in biological and water samples by cloud point extraction preconcentration and graphite furnace atomic absorption spectrometry detection.

    PubMed

    Sang, Hongbo; Liang, Pei; Du, Dan

    2008-06-15

    A cloud point extraction (CPE) method for the preconcentration of trace aluminum prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS) has been developed. The CPE method is based on the complex of Al(III) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), and then entrapped in non-ionic surfactant Triton X-114. PMBP was used not only as chelating reagent in CPE preconcentration, but also as chemical modifier in GFAAS determination. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of PMBP and Triton X-114, equilibration temperature and time, were investigated in detail. An enrichment factor of 37 was obtained for the preconcentration of Al(III) with 10 mL solution. Under the optimal conditions, the detection limit of this method for Al(III) is 0.09 ng mL(-1), and the relative standard deviation is 4.7% at 10 ng mL(-1) Al(III) level (n=7). The proposed method has been applied for determination of trace amount of aluminum in biological and water samples with satisfactory results.

  16. Distribution of pesticides in n-hexane/water and n-hexane/acetonitrile systems and estimation of possibilities of their extraction isolation and preconcentration from various matrices.

    PubMed

    Zayats, M F; Leschev, S M; Petrashkevich, N V; Zayats, M A; Kadenczki, L; Szitás, R; Szemán Dobrik, H; Keresztény, N

    2013-04-24

    Distribution of 150 most widely used pesticides of different chemical classes (amides, anilinopirimidines, aromatics, benzenesulfonates, carbamates, dicarboximides, organophosphorus compounds, phenyl esters, phenylureas, pyrazoles, pyrethroids, pyrimidines, strobilurins, sulfamides, triazines, triazoles, etc.) in n-hexane/water and n-hexane/acetonitrile systems was investigated at 25°C. Distribution constants of pesticides (P) have been calculated as ratio of pesticide concentration in n-hexane to its concentration in water or acetonitrile phase. HPLC and GC methods were used for pesticides determination in phases. It was found that the overwhelming majority of pesticides are hydrophobic, i.e. in n-hexane/water system LgP≫0, and the difference in LgP values can reach 9.1 units. Replacement of water for acetonitrile leads to dramatic fall of LgP values reaching 9.5 units. The majority of LgP values in this case are negative and their differences is strongly leveled in comparison with a hexane/water system. Thus, maximal difference in pesticides LgP values for n-hexane/acetonitrile system is 3.2 units. It is shown that n-hexane can be used for selective and efficient extraction and preconcentration of pesticides from water matrices. On the other hand, acetonitrile is effective for the isolation and preconcentration of pesticides from hydrocarbon and vegetable oil matrices. The distribution constants described in the paper may be effectively used for the estimation of possibilities of extraction isolation, preconcentration and separation of pesticides.

  17. A bulk liquid membrane-flow injection (BLM-FI) coupled system for the preconcentration and determination of vanadium in saline waters.

    PubMed

    Pinto, Juan J; García-Vargas, Manuel; Moreno, Carlos

    2013-01-15

    A bulk liquid membrane-flow injection (BLM-FI) system has been developed for the preconcentration and spectrophotometric determination of vanadium in saline waters. The preconcentration step was based on a bulk liquid membrane containing Aliquat 336 (acting as a carrier) dissolved in dodecane/dodecanol. Vanadium species were chemically pumped due to the pH gradient between the sample (pH 3.2) and the receiving solution (pH 9.8). Vanadium transport through the membrane was monitored by a new and sensitive spectrophotometric method based on its reaction with di-2-pyridyl ketone benzoylhydrazone (dPKBH) in an acidic medium. As a consequence of membrane transport, vanadium was recovered in an ammonium solution, where total vanadium concentration was spectrophotometrically determined at 375 nm, as the pentavalent species, by using a flow injection analysis (FIA) system. Under optimal conditions, this FIA system provided a detection limit of 4.7 μg L(-1) (3s(blank)/m) and RSD 2.72%, for vanadium determination in saline samples. Both preconcentration and determination steps were previously optimized by modified simplex methodologies. The proposed coupled method was successfully applied to the determination of vanadium in a certified reference material (TMDA-62) and in two seawater samples.

  18. The study of applicability of dithiocarbamate-coated fullerene C 60 for preconcentration of palladium for graphite furnace atomic absorption spectrometric determination in environmental samples

    NASA Astrophysics Data System (ADS)

    Leśniewska, Barbara A.; Godlewska, Iwona; Godlewska—Żyłkiewicz, Beata

    2005-03-01

    The present method comprises an off-line enrichment of Pd on the fullerene, C 60, coated with ammonium pyrrolidinedithiocarbamate (APDC), followed by the elution of formed Pd-chelate with ethanol and the subsequent determination of Pd from the eluate by graphite furnace atomic absorption spectrometry. By using fullerene loaded with 0.1% APDC, the analytical system is simplified as the sample can be directly preconcentrated on the column. The following parameters affecting the preconcentration of Pd on C 60 were optimized: amount of ligand used for the coating of fullerene, sample pH, kind of eluent, sample and eluent flow rates, volume and number of fractions of eluent used. The sorption efficiency for Pd on coated fullerene was 99.2±1.1%. The best elution efficiency for Pd from the column was obtained with 0.6 ml of ethanol at a flow rate of 0.2 ml min -1. The limit of detection was 0.044 ng ml -1. The effect of sample pretreatment procedure on the preconcentration of Pd by evaluated method is discussed. The content of Pd in road dust (179.2±17.4 ng g -1) determined by proposed method was in agreement with the results obtained with a reference method. The low recovery of analyte (64%) was obtained for geological material CRM SARM-7 (platinum ore) due to the much higher concentration of interfering elements.

  19. Rapid and highly sensitive determination of low-molecular-weight carbonyl compounds in drinking water and natural water by preconcentration HPLC with 2,4-dinitrophenylhydrazine.

    PubMed

    Takeda, Kazuhiko; Katoh, Shinya; Nakatani, Nobutake; Sakugawa, Hiroshi

    2006-12-01

    The aim of this research was to develop a simple procedure for a highly sensitive determination of low-molecular-weight (LMW) carbonyl compounds in drinking water and natural water. We employed a preconcentration HPLC system with 2,4-dinitrophenylhydrazine (DNPH) for the determination of LMW carbonyl compounds. A C-18 reverse-phase preconcentration column was used instead of a sample loop at the sample injection valve. A 0.1 - 5.0 mL portion of the derivatized sample solution was injected with a gas-tight syringe, and a 15% acetonitrile aqueous solution was pushed through the preconcentration column to remove the unreacted excess DNPH, which caused serious interference in the determination of formaldehyde. The detection limits were 1 - 3 nM with a relative standard deviation of 2 - 5% for 20 nM standard solutions (n = 5). The calibration curves were essentially unaffected by coexisting sea salts. Applications to commercial mineral water, tap water, river water, pond water and seawater are presented.

  20. Pre-concentration of trace elements in short chain alcohols using different commercial cation exchange resins prior to inductively coupled plasma-optical emission spectrometric detection.

    PubMed

    Nomngongo, Philiswa N; Catherine Ngila, J; Kamau, Joseph N; Msagati, Titus A M; Marjanovic, Ljiljana; Moodley, Brenda

    2013-07-17

    Chelex-100, Dowex 50W-x8 and Dowex MAC-3 exchange resins were investigated for separation and pre-concentration of trace amounts of Cd, Cr, Cu, Fe, Mn, Pb, Ti and Zn in alcohols with respect to retention and desorption characteristics. Dowex 50W-x8 was found to be the best sorbent with percentages recoveries >95%. In addition, Chelex-100 appeared to be suitable for the pre-concentration of Cu, Fe and Zn, whereas Dowex MAC-3 was selective for Cu and Fe. Therefore, Dowex 50W-x8 was used for further investigations. The relative standard deviations <4% (n=20), limits of detection and quantification were 0.1-1.2 μg L(-1) and 0.3-1.5 μg L(-1), respectively. The SPE method was validated against a certified reference material and the results were in agreement with certified values. The accuracy of the optimized method was verified by the recovery test in the spiked alcohol samples. The accuracy and spike recovery test for different metal ions were in the range 98-102% and 95-105%, respectively. The optimized method was applied to the separation and pre-concentration of metal ions in different commercial alcohol samples.