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Sample records for electrokinetic chromatographic study

  1. Micellar electrokinetic chromatographic study of hydroquinone and some of its ethers. Determination of hydroquinone in skin-toning cream.

    PubMed

    Sakodinskaya, I K; Desiderio, C; Nardi, A; Fanali, S

    1992-04-01

    The separation of hydroquinone and some of its ether derivatives was studied by micellar electrokinetic chromatography with sodium dodecyl sulphate as an anionic surfactant in the background electrolyte. The optimized method was used for the determination of hydroquinone in a sample of skin-toning cream. On-column detection at 254 nm with caffeine as an internal standard gave good quantitative results.

  2. Study of electrokinetic effects to quantify groundwater flow

    SciTech Connect

    Brown, S.R.; Haupt, R.W.

    1997-04-01

    An experimental study of electrokinetic effects (streaming potential) in earth materials was undertaken. The objective was to evaluate the measurement of electrokinetic effects as a method of monitoring and predicting the movement of groundwater, contaminant plumes, and other fluids in the subsurface. The laboratory experiments verified that the electrokinetic effects in earth materials are prominent, repeatable, and can be described well to first order by a pair of coupled differential equations.

  3. Micellar electrokinetic chromatographic determination of rosuvastatin in rabbit plasma and evaluation of its pharmacokinetics and interaction with niacin.

    PubMed

    El-Kommos, Michael E; Mohamed, Niveen A; Ali, Hassan R H; Abdel Hakiem, Ahmed F

    2014-12-01

    A specific, accurate, precise and reproducible micellar electrokinetic chromatographic method was developed for in vitro and in vivo estimation of rosuvastatin, a synthetic and potent HMG-CoA inhibitor, in rabbit plasma. Further, its pharmacokinetics in the presence of niacin, which could be co-administered for monitoring of severe hypercholestremia, was investigated. The assay procedures involved simple liquid-liquid extraction of rosuvastatin and internal standard, atorvastatin, from a small plasma volume directly into acetonitrile. The organic layer was separated and evaporated under a gentle stream of nitrogen. The residue was reconstituted in the mobile phase and injected electrokinetically into electropherosis system. The background electrolyte consisted of borate buffer (25.0 mm, pH 9.5), 10.0% organic modifier (5.0% methanol + 5.0% acetonitrile) and 25.0 mm sodium dodecyl sulfate at 20.0 kV applied voltage and 215.0 nm detection wavelength for the effective separation of rosuvastatin, niacin and atorvastatin.

  4. The Study of Porous Media with AC Electrokinetics

    NASA Astrophysics Data System (ADS)

    Pengra, David B.; Wong, Po-Zen

    1996-11-01

    Electrokinetic phenomena, which involve the coupling of fluid and electric currents, are present in many porous media systems. They arise from the presence of a space charge layer at the fluid/solid interface, and depend on characteristics of the interface and properties of the porous material. Although understood for years, electrokinetic phenomena have been typically too weak to use as an experimental probe of such systems. Recently we have shown that modern instrumentation, based on AC excitations, can be used to measure electrokinetic response in porous rock. From the measurements we derive the permeability of the rock exactly, and study other physicochemical properties. We review electrokinetic theory, describe our results for porous rock, and discuss present research using the AC techniques. Research supported by the Gas Research Institute, Contract 5090-260-1953, and National Science Foundation Grant DMR-9405672.

  5. Micellar electrokinetic capillary chromatographic determination of artificial sweeteners in low-Joule soft drinks and other foods.

    PubMed

    Thompson, C O; Trenerry, V C; Kemmery, B

    1995-03-10

    A rapid method for the determination of artificial sweeteners in low-Joule soft drinks and other foods by micellar electrokinetic capillary chromatography (MEKC) is described. Caffeine, benzoic acid and sorbic acid, which are often added to soft drinks, can also be determined with this procedure. The artificial sweeteners, aspartame, saccharin, acesulfame-K, alitame and dulcin, and the other food additives are well separated in less than 12 min using an uncoated fused-silica capillary column with a buffer consisting of 0.05 M sodium deoxycholate, 0.01 M potassium dihydrogenorthophosphate, 0.01 M sodium borate operating at 20 kV. Dehydroacetic acid was used as the internal standard for the determinations. The levels of artificial sweeteners, preservatives and caffeine were in good agreement with those determined by the high-performance liquid chromatographic (HPLC) procedure currently used in our Laboratory. The MEKC procedure has the same order of repeatability, is faster and less costly to operate than the HPLC method.

  6. Micellar electrokinetic chromatographic screening method for common sexual assault drugs administered in beverages.

    PubMed

    Bishop, Sandra C; Lerch, Margaret; McCord, Bruce R

    2004-04-20

    Recently, much attention has been given to benzodiazepines and gamma-hydroxybutyric acid (GHB) related compounds owing to their alleged widespread use as date-rape drugs. Toxicologists would greatly benefit from a screening method that allows for the simultaneous detection of both groups of substances. A new capillary electrophoresis (CE) method has been developed in the micellar mode to accomplish this separation in under 16 min using a sodium dodecyl sulfate (SDS)/sodium tetraborate/boric acid buffer with an acetonitrile organic modifier. Optimization of SDS and organic modifier concentration, along with pH, were performed on a set of standards containing eight benzodiazepines, GHB, gamma-butyrolactone, and the internal standard, sulfanilic acid. The method was shown to have a detection limit of less than 2 microg/ml for five out of eight benzodiazepines with a linear range of 2.5-100 microg/ml. The detection limit for GHB was 32 mg/ml with a linear range to 2500 microg/ml. This method was applied to the rapid analysis of spiked beverages. GHB spiked beverages were monitored after using a series of simple dilutions to determine the effects of time on the drug analysis. Possible interfering peaks from drugs of abuse and artifacts from a variety of different drink combinations were also studied in detail. A one-step liquid-liquid extraction was the only necessary sample pretreatment. PMID:15066708

  7. Chromatographic methods in the study of autism.

    PubMed

    Żurawicz, Ewa; Kałużna-Czaplińska, Joanna; Rynkowski, Jacek

    2013-10-01

    Research into biomarkers of autism is a new means of medical intervention in this disease. Chromatographic techniques, especially coupled with mass spectrometry, are widely used in determination of biomarkers and assessment of effectiveness of autism therapy owing to their sensitivity and selectivity. Among the chromatographic techniques gas chromatography and liquid chromatography, especially high-performance liquid chromatography, have found application in clinical trials. The high-performance liquid chromatography technique allows an analysis of liquid samples with a wide range of molecules, small and large, providing an opportunity to perform advanced assays within a short time frame. Gas chromatography with the appropriate preparation of samples (gaseous and liquid) and a selection of analysis conditions enables the separation of thermally stable, volatile and non-volatile organic substances in short runtimes. The chromatographic techniques that are currently used in metabolic studies in autism are designed to identify abnormalities in three areas: the metabolism of neurotransmitters, nutritional and metabolic status and manifestations of oxidative stress. This review presents a necessary theoretical introduction and examples of applications of chromatographic studies of disorder markers in autism.

  8. Micellar electrokinetic capillary chromatographic method for the quantitative analysis of uricosuric and antigout drugs in pharmaceutical preparations.

    PubMed

    Kou, Hwang-Shang; Lin, Tsai-Pei; Chung, Tang-Chia; Wu, Hsin-Lung

    2006-06-01

    A simple MEKC method is described for the separation and quantification of seven widely used uricosuric and antigout drugs, including allopurinol (AP), benzbromarone (BZB), colchicine (COL), orotic acid (OA), oxypurinol (OP), probenecid (PB), and sulfinpyrazone (SPZ). The drugs were separated in a BGE of borate buffer (45 mM; pH 9.00) with SDS (20 mM) as the micellar source and the separated drugs were directly monitored with a UV detector (214 nm). Several parameters affecting the separation and analysis of the drugs were studied. Based on the normalized peak-area ratios of the drugs to an internal standard versus the concentration of the drugs, the method is applicable to quantify BZB, COL, and SPZ (each 5-200 microM), AP, OA, OP, and PB (each 10-200 microM) with detection limits (S/N = 3, 0.5 psi, 5 s injection) in the range of 0.6-4.0 microM. The precision (RSD; n = 5) and accuracy (relative error; n = 5) of the method for intraday and interday analyses of the analytes at three levels (30, 120, and 180 microM) are below 4% (n = 3). The method was demonstrated to be suitable for the analysis of AP and COL in commercial tablets with speed and simplicity.

  9. Electrokinetic experimental study on saturated rock samples: zeta potential and surface conductance

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Hu, Hengshan; Guan, Wei; Li, Hui

    2015-05-01

    It is important to know the electrokinetic properties of crustal rocks for interpreting the conductivity mechanisms and seismoelectric phenomena during earthquakes and seismoelectric well logging. In this study, electrokinetic experiments are conducted using a special core-holder by employing an AC lock-in technique. A series of experiments are conducted on 10 sandstone samples to measure the streaming potentials and streaming currents, and the experiments on each sample are done at six different salinities. The streaming potential coefficient and streaming current coefficient are calculated from the measured streaming potentials and streaming currents. The experimental results show that streaming potential coefficient and streaming current coefficient decrease as the salinity increases. The dependence of these two coefficients on permeability and pore radius are analysed and compared with previous works. At low salinities, the streaming potential coefficient and streaming current coefficient increase with the increasing permeability and pore radius. At high salinities, the streaming potential coefficient (streaming current coefficient) almost share a same value for 10 different samples. This conclusion indicates that the differences of rock parameters can only be well recognized at lower salinities, and the electrokinetic signals are invalid at high salinities, which offers a restrictive condition for using the amplitude of electrokinetic signals to estimate rock parameters. The zeta-potential have also been estimated through combined measurements of streaming potential and streaming current. The surface conductivity and its contribution to electrokinetic effects are determined from a comparison of zeta-potentials by two different methods, and then the validation of the Helmholz-Smoluchowski equation for a capillary tube is tested in rocks. We also compare our date with theoretical and experimental works, and set up an expression about the relationship between

  10. Mechanistic studies of partial-filing micellar electrokinetic chromatography

    SciTech Connect

    Nelson, W.M.; Lee, C.S. |

    1996-09-15

    The need for coupling micellar electrokinetic chromatography (MEKC) with electrospray mass spectrometry initiates the development of partial-filling MEKC. In comparison with conventional MEKC, only a small portion of the capillary is filled with a micellar solution for performing the separation in partial-filling MEKC. Analytes first migrate into the micellar plug, where the separation occurs, and then into the leading electrophoresis buffer, which is free of surfactants. A theoretical model is proposed for predicting the separation behavior of triazine herbicides in partial-filling MEKC. The comparisons between conventional and partial-filling MEKC in terms of separation efficiency and resolution of triazine herbicides are presented and discussed. The optimization techniques, possible applications, and advantages of partial-filling MEKC are similarly addressed. 11 refs., 6 figs., 5 tabs.

  11. Numerical study of dc-biased ac-electrokinetic flow over symmetrical electrodes.

    PubMed

    Yang Ng, Wee; Ramos, Antonio; Cheong Lam, Yee; Rodriguez, Isabel

    2012-03-01

    This paper presents a numerical study of DC-biased AC-electrokinetic (DC-biased ACEK) flow over a pair of symmetrical electrodes. The flow mechanism is based on a transverse conductivity gradient created through incipient Faradaic reactions occurring at the electrodes when a DC-bias is applied. The DC biased AC electric field acting on this gradient generates a fluid flow in the form of vortexes. To understand more in depth the DC-biased ACEK flow mechanism, a phenomenological model is developed to study the effects of voltage, conductivity ratio, channel width, depth, and aspect ratio on the induced flow characteristics. It was found that flow velocity on the order of mm/s can be produced at higher voltage and conductivity ratio. Such rapid flow velocity is one of the highest reported in microsystems technology using electrokinetics. PMID:22662084

  12. Numerical study of dc-biased ac-electrokinetic flow over symmetrical electrodes

    PubMed Central

    Yang Ng, Wee; Ramos, Antonio; Cheong Lam, Yee; Rodriguez, Isabel

    2012-01-01

    This paper presents a numerical study of DC-biased AC-electrokinetic (DC-biased ACEK) flow over a pair of symmetrical electrodes. The flow mechanism is based on a transverse conductivity gradient created through incipient Faradaic reactions occurring at the electrodes when a DC-bias is applied. The DC biased AC electric field acting on this gradient generates a fluid flow in the form of vortexes. To understand more in depth the DC-biased ACEK flow mechanism, a phenomenological model is developed to study the effects of voltage, conductivity ratio, channel width, depth, and aspect ratio on the induced flow characteristics. It was found that flow velocity on the order of mm/s can be produced at higher voltage and conductivity ratio. Such rapid flow velocity is one of the highest reported in microsystems technology using electrokinetics. PMID:22662084

  13. Fundamentals of electrokinetics

    NASA Astrophysics Data System (ADS)

    Kozak, M. W.

    The study of electrokinetics is a very mature field. Experimental studies date from the early 1800s, and acceptable theoretical analyses have existed since the early 1900s. The use of electrokinetics in practical field problems is more recent, but it is still quite mature. Most developments in the fundamental understanding of electrokinetics are in the colloid science literature. A significant and increasing divergence between the theoretical understanding of electrokinetics found in the colloid science literature and the theoretical analyses used in interpreting applied experimental studies in soil science and waste remediation has developed. The soil science literature has to date restricted itself to the use of very early theories, with their associated limitations. The purpose of this contribution is to review fundamental aspects of electrokinetic phenomena from a colloid science viewpoint. It is hoped that a bridge can be built between the two branches of the literature, from which both will benefit. Attention is paid to special topics such as the effects of overlapping double layers, applications in unsaturated soils, the influence of dispersivity, and the differences between electrokinetic theory and conductivity theory.

  14. Retention Study of Flavonoids Under Different Chromatographic Modes.

    PubMed

    Sentkowska, Aleksandra; Biesaga, Magdalena; Pyrzynska, Krystyna

    2016-04-01

    The goal of this study was to investigate the chromatographic behavior of selected flavonoids from their different subgroups (flavonols, flavanones, flavones and isoflavones) in hydrophilic interaction liquid chromatography (HILIC). Chromatographic measurements were made on two different HILIC columns: cross-linked DIOL (Luna HILIC) and zwitterionic sulfoalkylbetaine (SeQuant ZIC-HILIC). Separation parameters such as the content of acetonitrile and pH of an eluent were studied. On the ZIC column, the retention factors of flavonoids increased with decreasing water content in the mobile phase. The increase in pH of the aqueous component mainly affects the polarity of the analytes. DIOL stationary phase shows more or less apparent dual retention mechanism, HILIC at the acetonitrile (ACN) content ≥75% and reversed phase (RP) with lower content of organic modifier. In the presence of ammonium acetate in the mobile phase, the retention of flavonoids onto the DIOL column increases without change in the selectivity of the separations. The similar effect, but considerably smaller was observed for aglycones on the ZIC column. The retention of studied glycosides (hesperidin, rutin) decreases in the presence of salt in the mobile phase. The significantly higher mass spectrometry sensitivity was observed under HILIC conditions in comparison with the most often used RP LC due to much higher content of ACN in the mobile phase. Finally, under optimal chromatographic conditions, the method was validated and applied for the determination of flavonoids in chamomile (Matricaria chamomilla L.) infusion. PMID:26668302

  15. Chromatographic selectivity study of 4-fluorophenylacetic acid positional isomers separation.

    PubMed

    Chasse, Tyson; Wenslow, Robert; Bereznitski, Yuri

    2007-07-13

    Unique properties of the fluorine atom stimulate widespread use and development of new organofluorine compounds in agrochemistry, biotechnology and pharmacology applications. However, relatively few synthetic methods exhibit a high degree of fluorination selectivity, which ultimately results in the presence of structurally related fluorinated isomers in the synthetic product. This outcome is undesirable from a pharmaceutical perspective as positional isomers possess different reactivity, biological activity and toxicity as compared to the desired product. It is advantageous to control positional isomers in the early stages of the synthetic process, as rejection and analysis of these isomers will likely become more difficult in later stages. The current work reports the development of a chromatographic analysis of 2- and 3-fluorophenylacetic acid positional isomer impurities in 4-fluorophenylacetic acid (4-FPAA), a building block in the synthesis of an active pharmaceutical ingredient. The method is employed as a part of a Quality by Design Approach to control purity of the starting material in order to eliminate the presence of undesirable positional isomers in the final drug substance. During method development, a wide range of chromatographic conditions and structurally related positional isomer probe molecules were exploited in an effort to gain insight into the specifics of the separation mechanism. For the systems studied it was shown that the choice of organic modifier played a key role in achieving acceptable separation. Further studies encompassed investigation of temperature influence on retention and selectivity of the FPAA isomers separation. Thermodynamic analysis of these data showed that the selectivity of the 2- and 4- fluorophenylacetic acids separation was dominated by an enthalpic process, while the selectivity of the 4- and 3-fluorophenylacetic acids separation was exclusively entropy driven (Delta(DeltaH degrees approximately 0). Studies of

  16. Electrokinetic pump

    DOEpatents

    Hencken, Kenneth R.; Sartor, George B.

    2004-08-03

    An electrokinetic pump in which the porous dielectric medium of conventional electrokinetic pumps is replaced by a patterned microstructure. The patterned microstructure is fabricated by lithographic patterning and etching of a substrate and is formed by features arranged so as to create an array of microchannels. The microchannels have dimensions on the order of the pore spacing in a conventional porous dielectric medium. Embedded unitary electrodes are vapor deposited on either end of the channel structure to provide the electric field necessary for electroosmotic flow.

  17. Interactions of structurally modified surfactants with reservoir minerals: Calorimetric, spectroscopic and electrokinetic study

    SciTech Connect

    Somasundaran, P.; Sivakumar, A.; Xu, Q.

    1991-03-01

    The objective of this project is to elucidate mechanisms of adsorption of structurally modified surfactants on reservoir minerals and to develop a full understanding of the effect of the surfactant structure on the nature of the adsorbed layers at the molecular level. An additional aim is to study the adsorption of surfactant mixtures on simple well-characterized minerals and on complex minerals representing real conditions. The practical goal of these studies is the identification of the optimum surfactant structures and their combinations for micellar flooding. In this work, the experiments on adsorption were focussed on the position of sulfonate and methyl groups on the aromatic ring of alkyl xylene sulfonates. A multi-pronged approach consisting of calorimetry, electrokinetics, wettability and spectroscopy is planned to elucidate the adsorption mechanism of surfactants and their mixtures on minerals such as alumina and kaolinite. 32 refs., 15 figs., 7 tabs.

  18. CHROMATOGRAPHIC AND MASS SPECTRAL STUDIES OF PERFLUOROOCTANESULFONATE AND THREE PERFLUOROOCTANESULFONAMIDES

    EPA Science Inventory

    The chromatographic and mass spectral characteristics of perfluorooctanesulfonate (PFOS) and three nitrogen-substituted perfluorooctanesulfonamides have been obtained. A methyl/phenol mixed phase fused silica capillary column was used for GC analysis, while a C18 reversed phase ...

  19. Electrokinetic pump

    DOEpatents

    Patel, Kamlesh D.

    2007-11-20

    A method for altering the surface properties of a particle bed. In application, the method pertains particularly to an electrokinetic pump configuration where nanoparticles are bonded to the surface of the stationary phase to alter the surface properties of the stationary phase including the surface area and/or the zeta potential and thus improve the efficiency and operating range of these pumps. By functionalizing the nanoparticles to change the zeta potential the electrokinetic pump is rendered capable of operating with working fluids having pH values that can range from 2-10 generally and acidic working fluids in particular. For applications in which the pump is intended to handle highly acidic solutions latex nanoparticles that are quaternary amine functionalized can be used.

  20. A laboratory feasibility study on a new electrokinetic nutrient injection pattern and bioremediation of phenanthrene in a clayey soil.

    PubMed

    Xu, Wei; Wang, Cuiping; Liu, Haibin; Zhang, Zhiyuan; Sun, Hongwen

    2010-12-15

    Electrokinetic (EK) injection has recently been proposed to supply nutrients and electron acceptors in bioremediation of low permeable soils. However, effective pH control and uniform injection of inorganic ions have yet to be developed. The present study investigated a new EK injection pattern, which combined electrolyte circulation and electrode polarity reversal on a clayey soil. Soil pH could be controlled ranging from 7.0 to 7.6 by circulating the mixed electrolyte at a suitable rate (800 mL/h in this study) without any buffer. Ammonium and nitrate ions were distributed more uniformly in soil by electrode polarity reversal. The developed electrokinetic injection technology was applied primarily in bioremediation of phenanthrene contaminated soil. Over 80% of the initial 200mg/kg phenanthrene in soil could be removed in 20 d, and greater phenanthrene removal was achieved using electrode polarity reversal. Hence, the present study provides a promising electrokinetic injection technology for bioremediation of contaminated soils. PMID:20870357

  1. A mechanistic study of arsenate removal from artificially contaminated clay soils by electrokinetic remediation.

    PubMed

    Suzuki, Tasuma; Moribe, Mai; Okabe, Yohhei; Niinae, Masakazu

    2013-06-15

    Batch desorption experiments and bench-scale electrokinetic experiments were performed to elucidate the electrokinetic remediation mechanisms of arsenate from artificially contaminated kaolinite. The electrokinetic experiments in which a constant voltage was applied demonstrated that high soil pH favored arsenate remediation with respect to both the remediation time and electricity consumption. It was also demonstrated that applying a pulse voltage (1 h ON, 1 h OFF) significantly improved the electricity consumption efficiency when the soil pH was maintained at the initial value during the experiments; this trend was not observed when the soil pH was gradually increased from the cathode side. These electrokinetic experimental results, with the support of arsenate desorption data obtained from batch experiments, indicate that the remediation rate-limiting step varied with soil pH. When the soil pH was maintained at the initial value of 7.2 during the experiments, arsenate desorption was the remediation rate-limiting step rather than the migration of dissolved arsenate toward the anode. Conversely, when the cathode pH was not controlled and the soil pH was correspondingly increased gradually from the cathode side, the migration of hydroxyl and desorbed arsenate ions toward the anode played a more important role in the control of the overall remediation efficiency. PMID:23643955

  2. Revealing fibrinogen monolayer conformations at different pHs: electrokinetic and colloid deposition studies.

    PubMed

    Nattich-Rak, Małgorzata; Adamczyk, Zbigniew; Wasilewska, Monika; Sadowska, Marta

    2015-07-01

    Adsorption mechanism of human fibrinogen on mica at different pHs is studied using the streaming potential and colloid deposition measurements. The fibrinogen monolayers are produced by a controlled adsorption under diffusion transport at pH of 3.5 and 7.4. Initially, the electrokinetic properties of these monolayers and their stability for various ionic strength are determined. It is shown that at pH 3.5 fibrinogen adsorbs irreversibly on mica for ionic strength range of 4×10(-4) to 0.15 M. At pH 7.4, a partial desorption is observed for ionic strength below 10(-2) M. This is attributed to the desorption of the end-on oriented molecules whereas the side-on adsorbed molecules remain irreversibly bound at all ionic strengths. The orientation of molecules and monolayer structure is evaluated by the colloid deposition measurements involving negatively charged polystyrene latex microspheres, 820 nm in diameter. An anomalous deposition of negative latex particles on substrates exhibiting a negative zeta potential is observed. At pH 3.5 measurable deposition of latex is observed even at low ionic strength where the approach distance of latex particles exceeded 70 nm. At pH 7.4 this critical distance is 23 nm. This confirms that fibrinogen monolayers formed at both pHs are characterized by the presence of the side-on and end-on oriented molecules that prevail at higher coverage range. It is also shown that positive charge is located at the end parts of the αA chains of the adsorbed fibrinogen molecules. Therefore, it is concluded that the colloid deposition method is an efficient tool for revealing protein adsorption mechanisms at solid/electrolyte interfaces.

  3. Environmental assessment on electrokinetic remediation of multimetal-contaminated site: a case study.

    PubMed

    Kim, Do-Hyung; Yoo, Jong-Chan; Hwang, Bo-Ram; Yang, Jung-Seok; Baek, Kitae

    2014-05-01

    In this study, an environmental assessment on an electrokinetic (EK) system for the remediation of a multimetal-contaminated real site was conducted using a green and sustainable remediation (GSR) tool. The entire EK process was classified into major four phases consisting of remedial investigations (RIs), remedial action construction (RAC), remedial action operation (RAO), and long-term monitoring (LTM) for environmental assessment. The environmental footprints, including greenhouse gas (GHG) emissions, total energy used, air emissions of criteria pollutants, such as NOx, SOx, and PM10, and water consumption, were calculated, and the relative contribution in each phase was analyzed in the environmental assessment. In the RAC phase, the relative contribution of the GHG emissions, total energy used, and PM10 emissions were 77.3, 67.6, and 70.4%, respectively, which were higher than those of the other phases because the material consumption and equipment used for system construction were high. In the RAO phase, the relative contributions of water consumption and NOx and SOx emissions were 94.7, 85.2, and 91.0%, respectively, which were higher than those of the other phases, because the water and electricity consumption required for system operation was high. In the RIs and LTM phases, the environmental footprints were negligible because the material and energy consumption was less. In conclusion, the consumable materials and electrical energy consumption might be very important for GSR in the EK remediation process, because the production of consumable materials and electrical energy consumption highly affects the GHG emissions, total energy used, and air emissions such as NOx and SOx. PMID:24515871

  4. Electrokinetics of non-Newtonian fluids: a review.

    PubMed

    Zhao, Cunlu; Yang, Chun

    2013-12-01

    This work presents a comprehensive review of electrokinetics pertaining to non-Newtonian fluids. The topic covers a broad range of non-Newtonian effects in electrokinetics, including electroosmosis of non-Newtonian fluids, electrophoresis of particles in non-Newtonian fluids, streaming potential effect of non-Newtonian fluids and other related non-Newtonian effects in electrokinetics. Generally, the coupling between non-Newtonian hydrodynamics and electrostatics not only complicates the electrokinetics but also causes the fluid/particle velocity to be nonlinearly dependent on the strength of external electric field and/or the zeta potential. Shear-thinning nature of liquids tends to enhance electrokinetic phenomena, while shear-thickening nature of liquids leads to the reduction of electrokinetic effects. In addition, directions for the future studies are suggested and several theoretical issues in non-Newtonian electrokinetics are highlighted.

  5. Tadpole toxicity prediction using chromatographic systems.

    PubMed

    Fernández-Pumarega, Alejandro; Amézqueta, Susana; Fuguet, Elisabet; Rosés, Martí

    2015-10-30

    Toxicity has been emulated in tadpole species through chromatographic systems. The parameter studied to evaluate the non-specific toxicity of a compound is the narcosis concentration (Cnar), which is defined as the concentration needed for the immobilization of the organism. Because experimental investigation with animals is lengthy, costly, technically difficult, and ethically questionable, there is a great interest in developing surrogate physicochemical systems able to emulate biological systems to obtain the same information in a faster, more economic, and easier manner. In order to see which chromatographic systems would be able to emulate tadpole narcosis, both, tadpole narcosis data and data in several chromatographic and electrophoretic systems, were fitted to a linear solvation energy relationship (LSER) model. Thus, by comparison of the models it was possible to see which of the chromatographic systems were more similar to the biological one. The physicochemical systems that best emulate tadpole narcosis were an HPLC system based on an immobilized artificial membrane (IAM) column, and two micellar electrokinetic chromatography (MEKC) systems based on sodium taurocholate (STC) and a mixture of sodium dodecylsulphate (SDS) and Brij 35 as surfactants. A system based on a RP18 HPLC column also was selected for comparison because it is a common column in most analytical laboratories. To establish the models, a set of compounds with known Cnar values were analyzed in the chromatographic, and electrophoretic selected systems and, then, the retention factor (k) was correlated to the concentration of narcosis. Statistics showed that the system based on STC micelles was the best to emulate toxicity in tadpoles. The robustness and predictive ability of the developed models were validated.

  6. Using Aspen to Teach Chromatographic Bioprocessing: A Case Study in Weak Partitioning Chromatography for Biotechnology Applications

    ERIC Educational Resources Information Center

    Evans, Steven T.; Huang, Xinqun; Cramer, Steven M.

    2010-01-01

    The commercial simulator Aspen Chromatography was employed to study and optimize an important new industrial separation process, weak partitioning chromatography. This case study on antibody purification was implemented in a chromatographic separations course. Parametric simulations were performed to investigate the effect of operating parameters…

  7. Electrokinetics as a Propellantless Propulsion Source

    NASA Astrophysics Data System (ADS)

    Valone, Thomas

    This is a review of the worthwhile, innovative theories and concepts in electrogravitics and electrokinetics that could yield tremendous technological and economic dividends in both investment dollars and potential applications for future generations. Electrogravitics is most commonly associated with the 1918 work by Professor Nipher followed by the 1928 British patent #300,311 of T. Townsend Brown, the 1952 Special Inquiry File #24-185 of the Office of Naval Research into the "Electro-Gravity Device of Townsend Brown" and two widely circulated 1956 Aviation Studies Ltd. Reports on "Electrogravitics Systems" and "The Gravitics Situation." By definition, electrogravitics historically has had a purported relationship to gravity or the object's mass, as well as the applied voltage. An analysis of the 90-year old science of electrogravitics (or electrogravity) necessarily includes an analysis of electrokinetics. Electrokinetics, on the other hand, is more commonly associated with many patents of T. Townsend Brown as well as Agnew Bahnson, starting with the 1960 US patent #2,949,550 entitled, "Electrokinetic Apparatus." Electrokinetics, which often involves a capacitor and dielectric, has virtually no relationship that can be connected with mass or gravity. The Army Research Lab has recently issued a report on electrokinetics, analyzing the force on an asymmetric capacitor, while NASA has received three patents on the same design topic. To successfully describe and predict the purported motion in the direction of the positive terminal of the capacitor, it is desirable to use the classical electrokinetic field and force equations for the specific geometry involved. This initial review also suggests directions for further confirming measurements. This paper also reviews the published electrokinetic experiments by the Army Research Lab by Bahder and Fazi, California State University at Fullerton work by Woodward and Mahood, Erwin Saxl, and others.

  8. Application of iron electrode corrosion enhanced electrokinetic-Fenton oxidation to remediate diesel contaminated soils: A laboratory feasibility study

    NASA Astrophysics Data System (ADS)

    Tsai, Tzai-Tang; Sah, Jygau; Kao, Chih-Ming

    2010-01-01

    SummaryDiesel soil contamination on gas stations or refinery plants is a worldwide environmental problem. The main objectives of this study were to (1) evaluate the efficiency of electrokinetic (EK) by using different electrode materials (graphite and iron rods) and electrolytes (tap water, 0.01 M NaCl, and 0.1 M NaCl) on the remediation of diesel contaminated soils, and (2) evaluate the feasibility of total petroleum hydrocarbon-diesel (TPH-D) reducing in soils via EK-Fenton oxidation enhanced by corroded iron electrode. The EK and EK-Fenton experiments were conducted in batch and sand box experiments, respectively. Batch experiments reveal that the most appropriate electrolyte was 0.1 M NaCl when iron electrode was used in the EK system. Sand box experiments indicate that the TPH-D concentration dropped from 10,000 to 300 mg kg -1 when amorphous iron/total iron (Fe o/Fe t) ratio increased from 0.1 to 0.33, with the addition of 8% of H 2O 2 and 0.1 M NaCl after 60 days of EK-Fenton operation. Electrokinetically enhanced oxidation with the presence of both H 2O 2 and Fe 3O 4 (iron electrode corrosion) resulted in higher TPH-D removal efficiency (97%) compared to the efficiencies observed from EK (55%) or Fenton oxidation (27%) alone. This demonstrates that EK-Fenton oxidation catalyzed by iron electrode corrosion is a valuable direction to efficiently and effectively remediate diesel contaminated soils.

  9. Chromatographic behaviour of steroidal saponins studied by high-performance liquid chromatography-mass spectrometry.

    PubMed

    Kite, Geoffrey C; Porter, Elaine A; Simmonds, Monique S J

    2007-05-01

    The chromatographic behaviour of steroidal saponins found in Anemarrhena asphodeloides, Asparagus officinalis, Convallaria majalis, Digitalis purpurea and Ruscus aculeatus was studied by HPLC-MS using a C-18 reversed-phase column and aqueous acetonitrile or aqueous methanol mobile phase gradients, with or without the addition of 1% acetic acid. The behaviour was compared to that of triterpene saponins found in Aesculus hippocastanum, Centella asiatica, Panax notoginseng and Potentilla tormentilla. Inclusion of methanol in the mobile phase under acidic conditions was found to cause furostanol saponins hydroxylated at C-22 to chromatograph as broad peaks, whereas the peak shapes of the spirostanol saponins and triterpene saponins studied remained acceptable. In aqueous methanol mobile phases without the addition of acid, furostanol saponins chromatographed with good peak shape, but each C-22 hydroxylated furostanol saponin was accompanied by a second chromatographic peak identified as its C-22 methyl ether. Methanolic extracts analysed in non-acidified aqueous acetonitrile mobile phases also resolved pairs of C-22 hydroxy and C-22 methoxy furostanol saponins. The C-22 methyl ether of deglucoruscoside was found to convert to deglucoruscoside during chromatography in acidified aqueous acetonitrile, or by dissolving in water. Poor chromatography of furostanol saponins in acidified aqueous methanol is due to the interconversion of the C-22 hydroxy and C-22 methoxy forms. It is recommended that initial analysis of saponins by HPLC-MS using a C-18 stationary phase is performed using acidified aqueous acetonitrile mobile phase gradients. The existence of naturally-occurring furostanol saponins methoxylated at C-22 can be investigated with aqueous acetonitrile mobile phases and avoiding methanol in the extraction solvent. PMID:17391684

  10. Electrokinetic desalination using honeycomb carbon nanotubes (HC-CNTs): a conceptual study by molecular simulation.

    PubMed

    Chen, Qile; Kong, Xian; Li, Jipeng; Lu, Diannan; Liu, Zheng

    2014-09-21

    A new concept of electrokinetic desalination using a CNT honeycomb is presented through molecular dynamics simulation. The preferential translocation of ions towards the outlets near two electrodes was realized by applying an electric field perpendicular to bulk fluid flow in a CNT network, which, in the meantime, generated deionized water flux discharged from the central outlets. The effects of the major factors such as electric field strength, numbers of separation units, diameter of CNT, and ion concentration on the desalination were examined. It was shown that over 95% salt rejection and around 50% fresh water recovery were achieved by the presented module by applying an electric field of 0.8 V nm(-1). CNT diameter, which is critical to ion rejection without the electric field, had a marginal effect on the desalination of this new module when a strong electric field was applied. The desalination was also not sensitive to ion concentration, indicating its excellent workability for a wide range of water salinity, e.g. from brackish water to seawater. A potential of mean force profile revealed a free energy barrier as large as 2.0-6.0 kcal mol(-1) for ions to move opposite to the implemented electrical force. The simulation confirmed the high potential of the CNT honeycomb in water desalination.

  11. Electrokinetic desalination using honeycomb carbon nanotubes (HC-CNTs): a conceptual study by molecular simulation.

    PubMed

    Chen, Qile; Kong, Xian; Li, Jipeng; Lu, Diannan; Liu, Zheng

    2014-09-21

    A new concept of electrokinetic desalination using a CNT honeycomb is presented through molecular dynamics simulation. The preferential translocation of ions towards the outlets near two electrodes was realized by applying an electric field perpendicular to bulk fluid flow in a CNT network, which, in the meantime, generated deionized water flux discharged from the central outlets. The effects of the major factors such as electric field strength, numbers of separation units, diameter of CNT, and ion concentration on the desalination were examined. It was shown that over 95% salt rejection and around 50% fresh water recovery were achieved by the presented module by applying an electric field of 0.8 V nm(-1). CNT diameter, which is critical to ion rejection without the electric field, had a marginal effect on the desalination of this new module when a strong electric field was applied. The desalination was also not sensitive to ion concentration, indicating its excellent workability for a wide range of water salinity, e.g. from brackish water to seawater. A potential of mean force profile revealed a free energy barrier as large as 2.0-6.0 kcal mol(-1) for ions to move opposite to the implemented electrical force. The simulation confirmed the high potential of the CNT honeycomb in water desalination. PMID:25092215

  12. Development of electrokinetic remediation for caesium: A feasibility study of 2D electrode configuration system

    NASA Astrophysics Data System (ADS)

    Syah Putra, Rudy

    2016-02-01

    Agar matrix was artificially contaminated with caesium and subjected to rapid assessment of electrokinetic treatment on the basis of the 2D electrode configuration. The effect of caesium concentration on the process was investigated using different electrode configuration (i.e. rectangular, hexagonal and triangular). During treatment the in situ pH distribution, the current flow, and the potential distribution were monitored. At the end of the treatment, the caesium concentration distribution was measured. The results of these experiments showed that for caesium contamination, pH control is essential in order to create a suitable environment throughout the agar matrix to enable contaminant removal. It was found that the type of electrode configuration used to control the pH affected the rate of caesium accumulation. All of the electrode configurations tested was effective, but the highest caesium extraction was achieved when the hexagonal pattern was used to control the pH. After 72 h of treatment at 50 mA, the concentration of caesium decreased gradually from the second and first layer of agar matrix throughout the cell, suggesting that most of the caesium was concentrated on the cathode part.

  13. Electrokinetic pumps and actuators

    SciTech Connect

    Phillip M. Paul

    2000-03-01

    Flow and ionic transport in porous media are central to electrokinetic pumping as well as to a host of other microfluidic devices. Electrokinetic pumping provides the ability to create high pressures (to over 10,000 psi) and high flow rates (over 1 mL/min) with a device having no moving parts and all liquid seals. The electrokinetic pump (EKP) is ideally suited for applications ranging from a high pressure integrated pump for chip-scale HPLC to a high flow rate integrated pump for forced liquid convection cooling of high-power electronics. Relations for flow rate and current fluxes in porous media are derived that provide a basis for analysis of complex microfluidic systems as well as for optimization of electrokinetic pumps.

  14. A Comparative Study of Chromatographic Behavior and Lipophilicity of Selected Imidazoline Derivatives.

    PubMed

    Filipic, Slavica; Antic, Aleksandra; Vujovic, Milena; Nikolic, Katarina; Agbaba, Danica

    2016-08-01

    Chromatographic behavior and lipophilicity of 20 selected imidazoline derivatives were examined by thin-layer chromatography using CN, RP-2, RP-8 and RP-18 as the stationary phases and a mixture of methanol, water and ammonia as the mobile phase. In all examined chromatographic systems, linear relationships were established between retention parameters and the volume fraction of methanol in the mobile phase (r > 0.985, 0.978, 0.981, 0.988 for the CN, RP-2, RP-8 and RP-18, respectively). The highest correlation between the obtained [Formula: see text] values was observed for RP-2 and RP-8 stationary phases. The experimental lipophilicity indices ([Formula: see text], m and C0) obtained from the retention data were used in correlation study with the calculated logP values. Experimentally determined [Formula: see text] values for all investigated chromatographic systems exhibited the highest correlation with the calculated ClogP values (r: 0.880, 0.872, 0.897 and 0.889 for the CN, RP-2, RP-8 and RP-18 stationary phases, respectively). In addition, principal component analysis enables new information about similarity and differences between tested compounds as well as experimental lipophilicity indices and calculated logP values. Performed QSRR analysis showed that the frequency of C-C at topological distance 1 and CATS2D Lipophilic-Lipophilic at lag 01 were important descriptors with influence on the [Formula: see text] values in all the examined chromatographic systems, while the differences in the retention behavior of compounds on the examined stationary phases can be distinguished based on their specific geometrical, electronic and constitutional properties.

  15. A comprehensive strategy in the development of a cyclodextrin-modified microemulsion electrokinetic chromatographic method for the assay of diclofenac and its impurities: Mixture-process variable experiments and quality by design.

    PubMed

    Orlandini, S; Pasquini, B; Caprini, C; Del Bubba, M; Squarcialupi, L; Colotta, V; Furlanetto, S

    2016-09-30

    A comprehensive strategy involving the use of mixture-process variable (MPV) approach and Quality by Design principles has been applied in the development of a capillary electrophoresis method for the simultaneous determination of the anti-inflammatory drug diclofenac and its five related substances. The selected operative mode consisted in microemulsion electrokinetic chromatography with the addition of methyl-β-cyclodextrin. The critical process parameters included both the mixture components (MCs) of the microemulsion and the process variables (PVs). The MPV approach allowed the simultaneous investigation of the effects of MCs and PVs on the critical resolution between diclofenac and its 2-deschloro-2-bromo analogue and on analysis time. MPV experiments were used both in the screening phase and in the Response Surface Methodology, making it possible to draw MCs and PVs contour plots and to find important interactions between MCs and PVs. Robustness testing was carried out by MPV experiments and validation was performed following International Conference on Harmonisation guidelines. The method was applied to a real sample of diclofenac gastro-resistant tablets. PMID:27623066

  16. Electrokinetic acceleration of DNA hybridization in microsystems.

    PubMed

    Lei, Kin Fong; Wang, Yun-Hsiang; Chen, Huai-Yi; Sun, Jia-Hong; Cheng, Ji-Yen

    2015-06-01

    In this work, electrokinetic acceleration of DNA hybridization was investigated by different combinations of frequencies and amplitudes of actuating electric signals. Because the frequencies from low to high can induce different kinds of electrokinetic forces, i.e., electroosmotic to electrothermal forces, this work provides an in-depth investigation of electrokinetic enhanced hybridization. Concentric circular Cr/Au microelectrodes of 350 µm in diameter were fabricated on a glass substrate and probe DNA was immobilized on the electrode surface. Target DNA labeled with fluorescent dyes suspending in solution was then applied to the electrode. Different electrokinetic forces were induced by the application of different electric signals to the circular microelectrodes. Local microfluidic vortexes were generated to increase the collision efficiency between the target DNA suspending in solution and probe DNA immobilized on the electrode surface. DNA hybridization on the electrode surface could be accelerated by the electrokinetic forces. The level of hybridization was represented by the fluorescent signal intensity ratio. Results revealed that such 5-min dynamic hybridization increased 4.5 fold of signal intensity ratio as compared to a 1-h static hybridization. Moreover, dynamic hybridization was found to have better differentiation ability between specific and non-specific target DNA. This study provides a strategy to accelerate DNA hybridization in microsystems. PMID:25863384

  17. Structure of Multiresponsive Brush-Decorated Nanoparticles: A Combined Electrokinetic, DLS, and SANS Study.

    PubMed

    Martin, Jennifer R S; Bihannic, Isabelle; Santos, Catarina; Farinha, José Paulo S; Demé, Bruno; Leermakers, Frans A M; Pinheiro, José P; Rotureau, Elise; Duval, Jérôme F L

    2015-04-28

    Particles consisting of a glassy poly(methyl methacrylate) core (ca. 40 nm in radius) decorated with a poly(N-isopropylacrylamide) anionic corona are synthesized using either methacrylic acid (MA) or acrylic acid (AA) as reactive comonomers in the shell. The different reactivity ratios of MA and AA toward N-isopropylacrylamide originates p(MA-N) and p(N-AA) particles with carboxylate charges supposedly located, preferentially, in the close vicinity of the core and at the shell periphery, respectively. The corresponding swelling features of these nanoparticles are addressed over a broad range of pH values (4 to 7.5), NaNO3 concentrations (3 to 200 mM), and temperatures (15 to 45 °C) by dynamic light scattering (DLS) and small angle neutron scattering (SANS). DLS shows that the swelling of the particle shells increases their thickness from ∼10 to 90 nm with decreasing temperature, ionic strength, or increasing pH, with the effect being more pronounced for p(N-AA) whose lower critical solution temperature is shifted to higher values compared to that of p(MA-N). Potentiometric titration and electrokinetic results further reflect the easier dissociation of carboxyl groups in p(N-AA) and a marked heterogeneous interfacial swelling of the latter with decreasing solution salt content. The DLS response of both particles is attributed to the multiresponsive nature of a peripheral dilute shell, while SANS only probes the presence of a quasi-solvent-free dense polymer layer, condensed on the core surface. The thickness of that layer slightly increases from ∼6 to 9.5 nm with increasing temperature from 15 to 45 °C (at 15 mM NaNO3 and pH 5) due to the collapse of the outer dilute shell layer. Overall, results evidence a nonideal brush behavior of p(MA-N) and p(N-AA) and their microphase segregated shell structure, which supports some of the conclusions recently formulated from approximate self-consistent mean-field computations.

  18. [Relativity study of the topological index of methylalkane structures and chromatographic retention index].

    PubMed

    Xiang, Zheng; Liang, Yizeng; Hu, Qiannan

    2005-03-01

    Quantitative structure-property relationships (QSPR) have been demonstrated to be a powerful tool in chromatography. QSPR have been used to obtain simple models to explain and predict the chromatographic behavior of various classes of compounds. The study of quantitative structure and retention index relationship (QSRR) is an important subject in chromatographic field. One hundred twenty-seven topological descriptors of 207 methylalkane structures are calculated. GAPLS method, which is a variable selection method combining with genetic algorithms (GA), back stepwise and partial least squares (PLS), is introduced in the variable selection of quantitative structure gas chromatographic (GC) retention index relationship. Seven topological descriptors are selected from 127 topological descriptors by GAPLS method to build QSRR model with high regression quality: squared correlation coefficient (R2) of 0.99998, standard deviation (S) of 2.88. The error of the model is similar to the experimental error. The validation of the model is checked by leave-one-out cross-validation technique. The result of leave-one-out cross-validation indicates that the built model is reliable and stable with high prediction quality, such as squared correlation coefficient of leave-one-out (R2cv) of 0.99997 and standard deviation of leave-one-out predictions (Scv) of 2.95. A successful interpretation of the complex relationship between GC retention indexes of methylalkanes and the chemical structure is achieved using QSPR method. The seven variables in the model are also rationally interpreted, which indicates methylalkane retention index are precisely represented by topological descriptors.

  19. New approaches to the kinetic study of alcoholic fermentation by chromatographic techniques.

    PubMed

    Lainioti, Georgia Ch; Karaiskakis, George

    2013-09-01

    The kinetics of the fermentation process has gained increasing interest, not only in the scientific community, but in the industrial world as well. Information concerning the improvement of batch fermentation performance may potentially be valuable for the designing of scale-up processes. Intensive studies have been conducted with the use of various chromatographic techniques, such as conventional gas chromatography, reversed-flow gas chromatography (RFGC), high-performance liquid chromatography, field-flow fractionation and others. In the present study, specific focus is placed on the employment of RFGC, a method that can successfully be applied for the determination of physicochemical quantities, such as reaction rate constants and activation energies, at each phase of the alcoholic fermentation. In contrast to conventional chromatographic techniques, RFGC can lead to substantial information referring to the evaluation of fermentation kinetics at any time of the process. Moreover, gravitational field-flow fractionation, a sub-technique of field-flow fractionation, presents the ability to monitor the proliferation of Saccharomyces cerevisiae cells through their elution profiles that can be related to the different cell growth stages. The combination of the two techniques can provide important information for kinetic study and the distinction of the growth phases of yeast cell proliferation during alcoholic fermentations conducted under different environmental conditions.

  20. Gas chromatographic determination of volatile congeners in spirit drinks: interlaboratory study.

    PubMed

    Kelly, J; Chapman, S; Brereton, P; Bertrand, A; Guillou, C; Wittkowski, R

    1999-01-01

    An interlaboratory study of a gas chromatographic (GC) method for the determination of volatile congeners in spirit drinks was conducted; 31 laboratories from 8 countries took part in the study. The method uses GC with flame ionization detection and incorporates several quality control measures which permit the choice of chromatographic system and conditions to be selected by the user. Spirit drink samples were prepared and sent to participants as 10 blind duplicate or split-level test materials for the determination of 1,1-diethoxyethane (acetal), 2-methylbutan-1-ol (active amyl alcohol), 3-methylbutan-1-ol (isoamyl alcohol), methanol (methyl alcohol), ethyl ethanoate (ethyl acetate), butan-1-ol (n-butanol), butan-2-ol (sec-butanol), 2-methylpropan-1-ol (isobutyl alcohol), propan-1-ol (n-propanol), and ethanal (acetaldehyde). The precision of the method for 9 of the 10 analytes was well within the range predicted by the Horwitz equation. The precision of the most volatile analyte, ethanal, was just above statistically predicted levels. This method is recommended for official regulatory purposes. PMID:10589492

  1. Investigation of electrokinetic decontamination of concrete

    SciTech Connect

    DePaoli, D.W.; Harris, M.T.; Morgan, I.L.; Ally, M.R.

    1995-12-31

    Experiments have been conducted to investigate the capabilities of electrokinetic decontamination of concrete. Batch equilibration studies have determined that the loading of cesium and strontium on concrete may be decreased using electrolyte solutions containing competing cations, while solubilization of uranium and cobalt, that precipitate at high pH, will require lixiviants containing complexing agents. Dynamic electrokinetic experiments showed greater mobility of cesium than strontium, while some positive results were obtained for the transport of cobalt through concrete using EDTA and for uranium using carbonate.

  2. Chromatographic instrumentation in space: past, present and future developments for exobiological studies

    NASA Astrophysics Data System (ADS)

    Raulin, F.; Sternberg, R.; Coscia, D.; Vidal-Madjar, C.; Millot, M.-C.; Sébille, B.; Israel, G.

    1999-01-01

    Several planetary exploration missions have already used chromatographic techniques to search for organic compounds, including complex organics, in extraterrestrial environments. So far, only gas chromatography (GC) has been used. In two cases (Viking and Cassini-Huygens), a Py-GC-MS instrument, coupling GC with a pyrolyzer and a mass spectrometer, has been flown. Powerful miniaturized Py-GC-MS instrumentation, with high resolution multi-GC columns and time-of-flight or Ion Trap mass spectrometers are under development, in the frame of the preparation of the Rosetta mission. There is now a strong need for new chromatographic instrumentation in space, in particular to perform detailed molecular analyses of complex non-volatile organics, including macromolecular compounds. Liquid Chromatography (LC), in particular High Performance Liquid Chromatography (HPLC) Supercritical Fluid Chromatography (SFC) or Chemical-Derivatization Gas Chromatography (CDGC) could provide a very efficient mean of analyzing a wide variety of exobiologically important compounds. LC or CDGC have never been used in space yet, but feasibility studies on their application in planetary mission are needed.

  3. Surface study of stainless steel electrode deposition from soil electrokinetic (EK) treatment using X-ray photoelectron spectroscopy (XPS)

    SciTech Connect

    Embong, Zaidi; Johar, Saffuwan; Tajudin, Saiful Azhar Ahmad; Sahdan, Mohd Zainizan

    2015-04-29

    Electrokinetic (EK) remediation relies upon application of a low-intensity direct current through the soil between stainless steel electrodes that are divided into a cathode array and an anode array. This mobilizes charged species, causing ions and water to move toward the electrodes. Metal ions and positively charged organic compounds move toward the cathode. Anions such as chloride, fluoride, nitrate, and negatively charged organic compounds move toward the anode. Here, this remediation techniques lead to a formation of a deposition at the both cathode and anode surface that mainly contributed byanion and cation from the remediated soil. In this research, Renggam-Jerangau soil species (HaplicAcrisol + RhodicFerralsol) with a surveymeter reading of 38.0 ± 3.9 μR/hr has been investigation in order to study the mobility of the anion and cation under the influence electric field. Prior to the EK treatment, the elemental composition of the soil and the stainless steel electrode are measured using XRF analyses. Next, the soil sample is remediated at a constant electric potential of 30 V within an hour of treatment period. A surface study for the deposition layer of the cathode and anode using X-ray Photoelectron spectroscopy (XPS) revealed that a narrow photoelectron signal from oxygen O 1s, carbon, C 1s silica, Si 2p, aluminium, Al 2p and chromium, Cr 2p exhibited on the electrode surface and indicate that a different in photoelectron intensity for each element on both electrode surface. In this paper, the mechanism of Si{sup 2+} and Al{sup 2+} cation mobility under the influence of voltage potential between the cathode and anode will be discussed in detail.

  4. Surface study of stainless steel electrode deposition from soil electrokinetic (EK) treatment using X-ray photoelectron spectroscopy (XPS)

    NASA Astrophysics Data System (ADS)

    Embong, Zaidi; Johar, Saffuwan; Tajudin, Saiful Azhar Ahmad; Sahdan, Mohd Zainizan

    2015-04-01

    Electrokinetic (EK) remediation relies upon application of a low-intensity direct current through the soil between stainless steel electrodes that are divided into a cathode array and an anode array. This mobilizes charged species, causing ions and water to move toward the electrodes. Metal ions and positively charged organic compounds move toward the cathode. Anions such as chloride, fluoride, nitrate, and negatively charged organic compounds move toward the anode. Here, this remediation techniques lead to a formation of a deposition at the both cathode and anode surface that mainly contributed byanion and cation from the remediated soil. In this research, Renggam-Jerangau soil species (HaplicAcrisol + RhodicFerralsol) with a surveymeter reading of 38.0 ± 3.9 μR/hr has been investigation in order to study the mobility of the anion and cation under the influence electric field. Prior to the EK treatment, the elemental composition of the soil and the stainless steel electrode are measured using XRF analyses. Next, the soil sample is remediated at a constant electric potential of 30 V within an hour of treatment period. A surface study for the deposition layer of the cathode and anode using X-ray Photoelectron spectroscopy (XPS) revealed that a narrow photoelectron signal from oxygen O 1s, carbon, C 1s silica, Si 2p, aluminium, Al 2p and chromium, Cr 2p exhibited on the electrode surface and indicate that a different in photoelectron intensity for each element on both electrode surface. In this paper, the mechanism of Si2+ and Al2+ cation mobility under the influence of voltage potential between the cathode and anode will be discussed in detail.

  5. Toxic elements in soil and groundwater: short-time study on electrokinetic removal of arsenic in the presence of other ions.

    PubMed

    Leszczynska, Danuta; Ahmad, Hafiz

    2006-06-01

    The electrokinetic technique is an emerging technology presently tested in situ to remove dissolved heavy metals from contaminated groundwater. There is a growing interest for using this system to cleanse clayey soil contaminated by toxic metallic ions. Currently, there are very few available non-destructive treatment methods that could be successfully applied in situ on low permeable type of soil matrix. The main objective of presented study was to validate and possibly enhance the overall efficiency of decontamination by the electrokinetic technique of the low permeable soil polluted by the arsenic in combination with chromium and copper ions. The chosen mixture of ions was imitating leak of pesticide well known as chromate copper arsenate (CCA). The chosen technique is showing a big promise to be used in the future as a portable, easy to install and run on sites with spills or leaks hard to reach otherwise; such as in the dense populated and urbanized areas. Laboratory electrokinetic experiments were designed to understand and possibly manipulate main mechanisms involved during forced migration of ions. All tests were conducted on artificially contaminated kaolinite (low permeable clay soil). Electrokinetic migration was inducted by the low voltage dc current applied through soil column. Series of experiments were designed to assess the efficiency of arsenic-chromium-copper remediation by applying (1) only dc current; and (2) by altering the soil environment. Obtained results showed that arsenic could be successfully removed from the soil in one day (25 hours) span. It was significant time reduction, very important during emergency response. Mass recovered at the end of each test depended on initial condition of soil and type of flushing solution. The best results were obtained, when soil was flushed with either NaOH or NaOCl (total removal efficiency 74.4% and 78.1%, respectively). Direct analysis of remained arsenic in soil after these tests confirmed

  6. Toxic Elements in Soil and Groundwater: Short-Time Study on Electrokinetic Removal of Arsenic in the Presence of other Ions

    PubMed Central

    Leszczynska, Danuta; Ahmad, Hafiz

    2006-01-01

    The electrokinetic technique is an emerging technology presently tested in situ to remove dissolved heavy metals from contaminated groundwater. There is a growing interest for using this system to cleanse clayey soil contaminated by toxic metallic ions. Currently, there are very few available non-destructive treatment methods that could be successfully applied in situ on low permeable type of soil matrix. The main objective of presented study was to validate and possibly enhance the overall efficiency of decontamination by the electrokinetic technique of the low permeable soil polluted by the arsenic in combination with chromium and copper ions. The chosen mixture of ions was imitating leak of pesticide well known as chromate copper arsenate (CCA). The chosen technique is showing a big promise to be used in the future as a portable, easy to install and run on sites with spills or leaks hard to reach otherwise; such as in the dense populated and urbanized areas. Laboratory electrokinetic experiments were designed to understand and possibly manipulate main mechanisms involved during forced migration of ions. All tests were conducted on artificially contaminated kaolinite (low permeable clay soil). Electrokinetic migration was inducted by the low voltage dc current applied through soil column. Series of experiments were designed to assess the efficiency of arsenic-chromium-copper remediation by applying (1) only dc current; and (2) by altering the soil environment. Obtained results showed that arsenic could be successfully removed from the soil in one day (25 hours) span. It was significant time reduction, very important during emergency response. Mass recovered at the end of each test depended on initial condition of soil and type of flushing solution. The best results were obtained, when soil was flushed with either NaOH or NaOCl (total removal efficiency 74.4% and 78.1%, respectively). Direct analysis of remained arsenic in soil after these tests confirmed

  7. Toxic elements in soil and groundwater: short-time study on electrokinetic removal of arsenic in the presence of other ions.

    PubMed

    Leszczynska, Danuta; Ahmad, Hafiz

    2006-06-01

    The electrokinetic technique is an emerging technology presently tested in situ to remove dissolved heavy metals from contaminated groundwater. There is a growing interest for using this system to cleanse clayey soil contaminated by toxic metallic ions. Currently, there are very few available non-destructive treatment methods that could be successfully applied in situ on low permeable type of soil matrix. The main objective of presented study was to validate and possibly enhance the overall efficiency of decontamination by the electrokinetic technique of the low permeable soil polluted by the arsenic in combination with chromium and copper ions. The chosen mixture of ions was imitating leak of pesticide well known as chromate copper arsenate (CCA). The chosen technique is showing a big promise to be used in the future as a portable, easy to install and run on sites with spills or leaks hard to reach otherwise; such as in the dense populated and urbanized areas. Laboratory electrokinetic experiments were designed to understand and possibly manipulate main mechanisms involved during forced migration of ions. All tests were conducted on artificially contaminated kaolinite (low permeable clay soil). Electrokinetic migration was inducted by the low voltage dc current applied through soil column. Series of experiments were designed to assess the efficiency of arsenic-chromium-copper remediation by applying (1) only dc current; and (2) by altering the soil environment. Obtained results showed that arsenic could be successfully removed from the soil in one day (25 hours) span. It was significant time reduction, very important during emergency response. Mass recovered at the end of each test depended on initial condition of soil and type of flushing solution. The best results were obtained, when soil was flushed with either NaOH or NaOCl (total removal efficiency 74.4% and 78.1%, respectively). Direct analysis of remained arsenic in soil after these tests confirmed

  8. Studies on improved integrated membrane-based chromatographic process for bioseparation

    NASA Astrophysics Data System (ADS)

    Xu, Yanke

    To improve protein separation and purification directly from a fermentation broth, a novel membrane filtration-cum-chromatography device configuration having a relatively impermeable coated zone near the hollow fiber module outlet has been developed. The integrated membrane filtration-cum-chromatography unit packed with chromatographic beads on the shell side of the hollow fiber unit enjoys the advantages of both membrane filtration and chromatography; it allows one to load the chromatographic media directly from the fermentation broth or lysate and separate the adsorbed proteins through the subsequent elution step in a cyclic process. Interfacial polymerization was carried out to coat the bottom section of the hollow fiber membrane while leaving the rest of the hollow fiber membrane unaffected. Myoglobin (Mb), bovine serum albumin (BSA) and a-lactalbumin (a-LA) were used as model proteins in binary mixtures. Separation behaviors of binary protein mixtures were studied in devices using either an ultrafiltration (UF) membrane or a microfiltration (MF) membrane. Experimental results show that the breakthrough time and the protein loading capacities were dramatically improved after coating in both UF and MF modules. For a synthetic yeast fermentation broth feed, the Mb and a-LA elution profiles for the four consecutive cyclic runs were almost superimposable. Due to the lower transmembrane flux in this device plus the periodical washing-elution during the chromatographic separation, fouling was not a problem as it is in conventional microfiltration. A mathematical model describing the hydrodynamic and protein loading behaviors of the integrated device using UF membrane with a coated zone was developed. The simulation results for the breakthrough agree well with the experimental breakthrough curves. The optimal length of the coated zone was obtained from the simulation. A theoretical analysis of the protein mass transfer was performed using a diffusion-convection model

  9. Validation study of gas chromatographic determination of pentachlorophenol in animal liver

    SciTech Connect

    Gillard, D.; Epstein, R.L.; Ashworth, R.B.; Curry, K.; Nathan, Q.

    1988-01-01

    A validation study was conducted of a gas chromatographic procedure for the determination of pentachlorophenol (PCP) in chicken, pork, and beef liver. Five analysts representing 5 laboratories analyzed randomly numbered blind duplicates at 3 fortified tissue concentrations and one incurred tissue on 2 consecutive days. The PCP concentrations ranged from approximately 40 to 400 parts per billion (ppb). All data were reported to 3 significant figures in ppb. The coefficients of variation for repeatability were between 2.8 and 8.5%, except for the beef liver, at a mean value of 80 ppb PCP, where the CV was 11.3%. The CVs for reproducibility were in the range of 9.7 - 16.5% with little significant difference by species. The CV asymptotically approached 10% as the PCP level increased.

  10. Electrokinetic effects near a membrane

    NASA Astrophysics Data System (ADS)

    Lacoste, David

    2009-03-01

    We discuss the electrostatic and electrokinetic contribution to the elastic moduli of a cell or artificial membrane placed in an electrolyte and driven by a DC electric field. The field drives ion currents across the membrane, through specific channels, pumps or natural pores. In steady state, charges accumulate in the Debye layers close to the membrane, modifying the membrane elastic moduli. We first study a model of a membrane of zero thickness, later generalizing this treatment to allow for a finite thickness and finite dielectric constant. Our results clarify and extend the results presented in [D. Lacoste, M. Cosentino Lagomarsino, and J. F. Joanny, Europhys. Lett., 77, 18006 (2007)], by providing a physical explanation for a destabilizing term proportional to kps^3 in the fluctuation spectrum, which we relate to a nonlinear (E^2) electro-kinetic effect called induced-charge electro-osmosis (ICEO). Recent studies of ICEO have focused on electrodes and polarizable particles, where an applied bulk field is perturbed by capacitive charging of the double layer and drives flow along the field axis toward surface protrusions; we predict similar ICEO flows around driven membranes, due to curvature-induced tangential fields within a non-equilibrium double layer, which hydrodynamically enhance protrusions.

  11. Dielectric decrement effects in electrokinetics

    NASA Astrophysics Data System (ADS)

    Figliuzzi, Bruno; Chan, Wai Hong Ronald; Buie, Cullen; Moran, Jeffrey

    2015-11-01

    Understanding the nonlinear phenomena that occur in the electric double layer (EDL) that forms at charged surfaces is a key issue in electrokinetics. In recent studies, Nakayama and Andelman [J. Chem. Physics 2015] Hatlo et al. [EPL 2012], and Zhao and Zhai [JFM 2013] demonstrated that dielectric decrement significantly influences the ionic concentration in the electric double layer (EDL) at high zeta potential, leading to the formation of a condensed layer near the particle's surface. In this presentation, we apply the dielectric decrement model to study two archetypal problems in electrokinetics, namely the electrophoresis of particles with fixed surface charges and the electrophoresis of ideally polarizable particles. Our aim is to rely on numerical simulations to incorporate nonlinear effects including crowding effects due to the finite size of ions, dielectric decrement in the EDL, surface conduction, concentration polarization and advection in the bulk solution. In parallel, we derive a simplified composite layer model that enables us to obtain analytical estimates of the physical quantities involved in the physical description of the problem.

  12. Electrokinetic effects on detection time of nanowire biosensor

    NASA Astrophysics Data System (ADS)

    Liu, Yaling; Guo, Qingjiang; Wang, Shunqiang; Hu, Walter

    2012-04-01

    We develop a multiphysics model to study the contribution of electrokinetics on the biomolecular detection process and provide a physical explanation of the two to three orders of magnitude difference in detection time between experimental results and theoretical predications at ultralow concentration. The electrokinetic effects, including electrophoretic force and electroosmotic flow, have been systematically studied under various sensor design and test conditions. In a typical single nanowire-based sensor, it is found that electrokinetic effects could result in a reduction of detection time over 90 times, compared with that induced by pure biomolecular diffusion. The detection time difference is further enhanced by increasing the applied gate voltage or the number of nanowires. It is proposed that accelerated biomolecular detection at ultralow concentration could be achieved by appropriate combinations of electrokinetic effects and nanowire sensor design.

  13. Use of a biomimetic chromatographic stationary phase for study of the interactions occurring between inorganic anions and phosphatidylcholine membranes.

    PubMed Central

    Hu, Wenzhi; Haddad, Paul R; Hasebe, Kiyoshi; Mori, Masanobu; Tanaka, Kazuhiko; Ohno, Masako; Kamo, Naoki

    2002-01-01

    A liquid chromatographic method for the study of ion-membrane interactions is reported. A phosphatidylcholine biomimetic stationary phase was established by loading dimyristoylphosphatidylcholine (DMPC) onto a reversed-phase octadecylsilica packed column. This column was then used to study the interaction of some inorganic anions with the stationary phase by UV and conductivity detection. Ten inorganic anions were selected as model ions and were analyzed with the proposed chromatographic system. Anion-DMPC interactions of differing magnitudes were observed for all of the model anions. Perchlorate-DMPC interactions were strongest, followed by thiocyanate-DMPC, iodide-DMPC, chlorate-DMPC, nitrate-DMPC, bromide-DMPC, chloride-DMPC, fluoride-DMPC, and then sulfate-DMPC. Cations in the eluent, especially H(+) ions and divalent cations such as Ca(2+), showed strong effects on anion-DMPC interactions. The chromatographic data suggest that DMPC interacts with both the anions and the cations. Anion-DMPC interactions were dependent on the surface potential of the stationary phase: at low surface potentials anion-DMPC interactions were predominantly solvation dependent in nature whereas at more positive surface potentials anion-DMPC interactions were predominantly electrostatic in nature. Cation-DMPC interactions served to raise the surface potential, causing the anion-DMPC interactions to vary from solvation dependent to electrostatic. The chromatographic data were used to provide quantitative estimates of the enthalpies of the anion-DMPC interactions. PMID:12496102

  14. ELECTROKINETICS, INC. INSITU BIO REMEDIATION BY ELECTROKINETIC INJECTION EMERGING TECHNOLOGY SUMMARY

    EPA Science Inventory

    Electrokinetics, Inc. through a cooperative agreement with USEPA's NRMRL conducted a laboratory evaluation of electrokinetic transport as a means to enhance in-situ bioremediation of trichloroethene (TCE). Four critical aspects of enhancing bioremediation by electrokinetic inject...

  15. Systematic Robustness Testing of a Liquid Chromatographic Method: A Case Study.

    PubMed

    Mannemala, Sai Sandeep; Kannappan, Valliappan

    2015-01-01

    Robustness testing of a method plays a crucial role in establishing its reliability. It examines the potential sources of variability in one or more responses of the proposed method. In this study, the robustness testing of a method proposed for simultaneous determination of warfarin and its two process related impurities was evaluated by using two level, fractional factorial design. Factors that are sensitive to a variation during method transfer were selected as independent variables [aqueous content (range: 39-43%, v/v), concentration of acetic acid (range: 0.08-0.12%, v/v), flow rate (range: 0.93-1.33 mL/min), and wavelength (range: 218-222 nm)]. Variables that determine the quality of separation, viz., retention factor of the first peak, resolution between the critical peak pair, tailing factor of warfarin, and total analysis time were selected as responses. Robustness was assessed by graphical (half normal probability and Pareto plots) and statistical (analysis of variance) methods. It was found that, among the studied variables, aqueous content had a significant effect on capacity factor and analysis time. Furthermore, non-significant intervals for significant factors were established by contour profiling. This study demonstrated the significance of experimental design and other statistical tools in understanding the effects of investigating factors of the chromatographic system and in defining their limits. PMID:26651591

  16. Mechanism of immonoglobulin G adsorption on mica-AFM and electrokinetic studies.

    PubMed

    Dąbkowska, Maria; Adamczyk, Zbigniew

    2014-06-01

    Adsorption of immunoglobulin G (IgG) from aqueous NaCl solutions of the concentration 10(-3)-0.15M on mica was studied. Initially, the kinetics was evaluated at pH 3.5 by direct AFM imaging. A monotonic increase in the maximum coverage of IgG with NaCl concentration was observed. These results were interpreted in terms of the theoretical model postulating an irreversible adsorption of the protein governed by the random sequential adsorption (RSA) model. Additionally, IgG adsorption and desorption was studied under in situ conditions, with streaming potential measurements. These measurements revealed that the maximum coverage of irreversibly adsorbed IgG varies from 0.37mgm(-2) for 10(-3)M, NaCl to 1.2mgm(-2) for 0.15M, NaCl. The significant role of ionic strength was attributed to the lateral electrostatic repulsion among adsorbed IgG molecules, positively charged at this pH value. These experimental results confirmed that monolayers of irreversibly bound IgG can be produced by adjusting ionic strength of the protein solution. In further experiments the stability and acid base properties of such monolayers were studied using the streaming potential method. It revealed that the monolayers were stable against pH cycling for the range from 3.5 to 9.5. The isoelectric point of mica supported IgG monolayers was 5.9, similar to derived from the micro-electrophoretic measurements in the bulk (5.8). Beside significance for basic sciences, the results indicate that thorough characteristics of IgG can be acquired via streaming potential measurements using microgram quantities of the protein.

  17. Liquid chromatographic determination of free glutamic acid in soup, meat product, and Chinese food: interlaboratory study.

    PubMed

    Beljaars, P R; van Dijk, R; Bisschop, E; Spiegelenberg, W M

    1996-01-01

    An interlaboratory study of the liquid chromatographic (LC) determination of free glutamic acid in soup, meat product, and Chinese food was performed. Homogenized food samples were extracted with hot water, filtered, and diluted. Aliquot portions were treated with N,N-dimethyl-2-mer-capto-ethyl-ammonium chloride (DMMAC) and o-phtaldialdehyde (OPA) to convert glutamic acid to a stable fluorescent complex. After LC separation on a reversed-phase C18 column with acetonitrile-phosphate buffer (pH 7.0)-water (80 + 180 + 740, v/v) as mobile phase, glutamic acid peaks were measured fluorometrically (excitation, 340 nm, and emission, 389 and/or 440 nm). Homocysteic acid was used as internal standard. Twelve samples (6 blind duplicates) containing about 0.3-1.3% (w/w) of glutamic acid were analyzed singly by 12 laboratories. Results from one participant were excluded. Repeatability relative standard deviations (RSDr) varied from 1.3 to 4.5%, and reproducibility relative standard deviations (RSDR) ranged from 4.1 to 7.1%. Average recovery of glutamic acid determined at 6 levels was 101.5% (range, 98-106%).

  18. Liquid chromatographic determination of histamine in fish, sauerkraut, and wine: interlaboratory study.

    PubMed

    Beljaars, P R; Van Dijk, R; Jonker, K M; Schout, L J

    1998-01-01

    An interlaboratory study of the liquid chromatographic (LC) determination of histamine in fish, sauerkraut, and wine was conducted. Diminuted and homogenized samples were suspended in water followed by clarification of extracts with perchloric acid, filtration, and dilution with water. After LC separation on a reversed-phase C18 column with phosphate buffer (pH 3.0)--acetonitrile (875 + 125, v/v) as mobile phase, histamine was measured fluorometrically (excitation, 340 nm; emission, 455 nm) in samples and standards after postcolumn derivatization with o-phthaldialdehyde (OPA). Fourteen samples (including 6 blind duplicates and 1 split level) containing histamine at about 10-400 mg/kg or mg/L were analyzed singly according to the proposed procedure by 11 laboratories. Results from one participant were excluded from statistical analysis. For all samples analyzed, repeatability relative standard deviations varied from 2.1 to 5.6%, and reproducibility relative standard deviations ranged from 2.2 to 7.1%. Averaged recoveries of histamine for this concentration range varied from 94 to 100%.

  19. An intensive study on the optical, rheological, and electrokinetic properties of polyvinyl alcohol-capped nanogold

    NASA Astrophysics Data System (ADS)

    Behera, Manoranjan

    2015-05-01

    Low-temperature-assisted wet chemical synthesis of nanogold (NG) using gold hydroxide, a new precursor salt in the presence of a macroscopic ligand poly(vinyl alcohol) PVA in water in the form of nanofluid, is reported for the first time in this article. In the absorption spectra, the surface Plasmon resonance absorption band in the range of 520-545 nm signifies the formation of NG via a controlled Au3+ + 3e → Au reaction grafted in small assemblies with polymer. Absorption maximum increases nonlinearly with Au-contents up to 100 µM Au in Au-PVA charge-transfer complex. Marked enhancement in the peak intensity of some of the vibration bands of PVA polymer such as C-H stretching, C=O stretching, CH2 bending, and C-C in-plane bending in the presence of NG reveals an interfacial interaction between NG and oxidized PVA via C=O group. Execution of shear thinning behavior regardless of the Au-content strongly suggests that crosslinking exists between NG and PVA in Au-PVA rheo-optical nanofluids. Hydrodynamic diameter and polydispersity index draw a nonlinear path with the Au doping with 30.0 g/L PVA in water over a wide region of 5-100 μM Au covered in this study. Enhancement in the zetapotential of Au-PVA nanofluid over bare PVA in water is ascribed to buildup of nonbonding electrons of "-C=O" moieties from the oxidized PVA on the NG surface. Displaying of lattice fringes in the microscopic image of core-shell Au-PVA nanostructure confirms that crystalline nature of NG core with inter planar spacing 0.235 nm corresponds to Au (111) plane.

  20. Electrokinetic decontamination of concrete

    SciTech Connect

    Lomasney, H.

    1995-10-01

    The U.S. Department of Energy has assigned a priority to the advancement of technology for decontaminating concrete surfaces which have become contaminated with radionuclides, heavy metals, and toxic organics. This agency is responsible for decontamination and decommissioning of thousands of buildings. Electrokinetic extraction is one of the several innovative technologies which emerged in response to this initiative. This technique utilizes an electropotential gradient and the subsequent electrical transport mechanism to cause the controlled movement of ionics species, whereby the contaminants exit the recesses deep within the concrete. This report discusses the technology and use at the Oak Ridge k-25 plant.

  1. Electrokinetic decontamination of concrete

    SciTech Connect

    Lomasney, H.L.; SenGupta, A.K.; Yachmenev, V.

    1996-12-31

    ELECTROSORB Electrokinetic Extraction Technology, developed by ISOTRON Corp., offers a cost-effective approach to treating contaminated concrete. Heavy metals/radionuclides trapped in concrete can be extracted using this process if they are chemically solubilized; solubilizers used are citric acid alone and a mixture of citric and nitric acids. A DC electric field is applied across the contaminated concrete to electrokinetically transport the solubilized contaminants from the concrete pores to a collector on the concrete surface. The collector is an extraction pad laid on the surface. The pad provides confinement for a planar electrode and solubilizer solution; it is operated under a vacuum to hold the pad against the concrete surface. Operation requires little attendance, reducing the workers` health hazards. The process incorporates a mechanism for recycling the solubilizer solution. A field demonstration of the process took place in Building 21 of DOE`s Mound facility in Miamisburg, OH, over 12 days in June 1996. The thorium species present in this building`s concrete floors included ThO{sub 2} and thorium oxalate. The nitric acid was found to facilitate Th extraction.

  2. Immersed molecular electrokinetic finite element method

    NASA Astrophysics Data System (ADS)

    Kopacz, Adrian M.; Liu, Wing K.

    2013-07-01

    A unique simulation technique has been developed capable of modeling electric field induced detection of biomolecules such as viruses, at room temperatures where thermal fluctuations must be considered. The proposed immersed molecular electrokinetic finite element method couples electrokinetics with fluctuating hydrodynamics to study the motion and deformation of flexible objects immersed in a suspending medium under an applied electric field. The force induced on an arbitrary object due to an electric field is calculated based on the continuum electromechanics and the Maxwell stress tensor. The thermal fluctuations are included in the Navier-Stokes fluid equations via the stochastic stress tensor. Dielectrophoretic and fluctuating forces acting on the particle are coupled through the fluid-structure interaction force calculated within the surrounding environment. This method was used to perform concentration and retention efficacy analysis of nanoscale biosensors using gold particles of various sizes. The analysis was also applied to a human papillomavirus.

  3. Electrokinetic remediation prefield test methods

    NASA Technical Reports Server (NTRS)

    Hodko, Dalibor (Inventor)

    2000-01-01

    Methods for determining the parameters critical in designing an electrokinetic soil remediation process including electrode well spacing, operating current/voltage, electroosmotic flow rate, electrode well wall design, and amount of buffering or neutralizing solution needed in the electrode wells at operating conditions are disclosed These methods are preferably performed prior to initiating a full scale electrokinetic remediation process in order to obtain efficient remediation of the contaminants.

  4. Stability and electrokinetic potential of silicon carbide suspensions in aqueous organic media

    NASA Technical Reports Server (NTRS)

    Yeremenko, B. V.; Lyubchenko, I. N.; Skobets, I. Y.

    1984-01-01

    The method of electroosmosis was used to study the dependence of the electrokinetic potential of silicon carbide suspensions in mixtures of water -n. alcohol. The reasons for the dependence of the electrokinetic potential on the composition of the intermicellar liquid are discussed.

  5. Tensorial electrokinetics in articular cartilage.

    PubMed

    Reynaud, Boris; Quinn, Thomas M

    2006-09-15

    Electrokinetic phenomena contribute to biomechanical functions of articular cartilage and underlie promising methods for early detection of osteoarthritic lesions. Although some transport properties, such as hydraulic permeability, are known to become anisotropic with compression, the direction-dependence of cartilage electrokinetic properties remains unknown. Electroosmosis experiments were therefore performed on adult bovine articular cartilage samples, whereby fluid flows were driven by electric currents in directions parallel and perpendicular to the articular surface of statically compressed explants. Magnitudes of electrokinetic coefficients decreased slightly with compression (from approximately -7.5 microL/As in the range of 0-20% compression to -6.0 microL/As in the 35-50% range) consistent with predictions of microstructure-based models of cartilage material properties. However, no significant dependence on direction of the electrokinetic coupling coefficient was detected, even for conditions where the hydraulic permeability tensor is known to be anisotropic. This contrast may also be interpreted using microstructure-based models, and provides insights into structure-function relationships in cartilage extracellular matrix and physical mediators of cell responses to tissue compression. Findings support the use of relatively simple isotropic modeling approaches for electrokinetic phenomena in cartilage and related materials, and indicate that measurement of electrokinetic properties may provide particularly robust means for clinical evaluation of cartilage matrix integrity.

  6. ELECTROKINETIC REMEDIATION: BASICS AND TECHNOLOGY STATUS

    EPA Science Inventory

    Electrokinetic remediation, variably named as electrochemical soil processing, electromigration, electrokinetic decontamination or electroreclamation uses electric currents to extract radionuclides, heavy metals, certain organic compounds, or mixed inorganic species and some orga...

  7. EMERGING TECHNOLOGY BULLETIN: ELECTROKINETIC SOIL PROCESSING

    EPA Science Inventory

    Electrokinetic Soil Processing (or Electrokinetic Remediation) uses two series of electrodes (anodes and cathodes) positioned inside compartments that allow egress and ingress of pore fluids to the porous media. The compartments are filled with water or other process fluids and ...

  8. Field Implementation of Electrokinetic-ISCO Remediation

    NASA Astrophysics Data System (ADS)

    Wu, M. Z.; Reynolds, D. A.; Fourie, A.; Thomas, D.; Prommer, H.

    2010-12-01

    Challenges remain in the remediation of low-permeability porous media (e.g. clays, silts) contaminated with dissolved and sorbed organic contaminants. Current remediation technologies, such as in-situ chemical oxidation (ISCO), are often ineffective and the treatment region is limited by very slow rates of groundwater flow (advection) or molecular diffusion. Several studies (e.g. Reynolds et al. 2008) have highlighted the potential at a laboratory scale for utilising electrokinetic transport, through the application of an electric field, to deliver a remediation compound (e.g. permanganate, persulfate) within heterogeneous and low-permeability sediments for ISCO (termed EK-ISCO) or other treatments. A numerical modelling approach is highly beneficial to optimise the efficacy of EK-ISCO remediation. A numerical model was developed that simulates groundwater flow and multi-species reactive transport under hydraulic and electric gradients (Wu et al. 2010). Coupled into the existing, previously verified reactive transport model PHT3D (Prommer, Barry and Zheng 2003), the model was verified against analytical and experimental studies. This study, through numerical modelling, investigated the feasibility of various factors, such as electrode configurations, applied voltage and oxidant loading, for EK-ISCO treatment at several field sites. Successful in situ oxidation is dependent upon the electrokinetic transport and dispersal of oxidant through the contaminated region, however this is limited by modelled conditions such as natural oxidant demand and contaminant phase. Electrode configurations investigated included one-dimensional or two-dimensional configurations, unidirectional, bidirectional or rotational operations, and position of oxidant injection. References Prommer, H, Barry, DA and Zheng, C 2003, 'MODFLOW/MT3DMS-Based Reactive Multicomponent Transport Modeling', Ground Water, vol. 41, no. 2, pp. 247-257. Reynolds, DA, Jones, EH, Gillen, M, Yusoff, I and Thomas

  9. Laboratory Experiment on Electrokinetic Remediation of Soil

    ERIC Educational Resources Information Center

    Elsayed-Ali, Alya H.; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E.

    2011-01-01

    Electrokinetic remediation is a method of decontaminating soil containing heavy metals and polar organic contaminants by passing a direct current through the soil. An undergraduate chemistry laboratory is described to demonstrate electrokinetic remediation of soil contaminated with copper. A 30 cm electrokinetic cell with an applied voltage of 30…

  10. Electrokinetic induced solute dispersion in porous media; pore network modeling

    NASA Astrophysics Data System (ADS)

    Li, Shuai; Schotting, Ruud; Raoof, Amir

    2013-04-01

    Electrokinetic flow plays an important role in remediation process, separation technique, and chromatography. The solute dispersion is a key parameter to determine transport efficiency. In this study, we present the electrokinetic effects on solute dispersion in porous media at the pore scale, using a pore network model. The analytical solution of the electrokinetic coupling coefficient was obtained to quantity the fluid flow velocity in a cylinder capillary. The effect of electrical double layer on the electrokinetic coupling coefficient was investigated by applying different ionic concentration. By averaging the velocity over cross section within a single pore, the average flux was obtained. Applying such single pore relationships, in the thin electrical double layer limit, to each and every pore within the pore network, potential distribution and the induced fluid flow was calculated for the whole domain. The resulting pore velocities were used to simulate solute transport within the pore network. By averaging the results, we obtained the breakthrough curve (BTC) of the average concentration at the outlet of the pore network. Optimizing the solution of continuum scale advection-dispersion equation to such a BTC, solute dispersion coefficient was estimated. We have compared the dispersion caused by electrokinetic flow and pure pressure driven flow under different Peclet number values. In addition, the effect of microstructure and topological properties of porous media on fluid flow and solute dispersion is presented, mainly based on different pore coordination numbers.

  11. Chromatographic and fluorescence spectroscopic studies of individual 7,12-dimethylbenz(a)anthracene--deoxyribonucleoside adducts

    SciTech Connect

    Moschel, R.C.; Pigott, M.A.; Costantino, N.; Dipple, A.

    1983-09-01

    Compared with standard Sephadex LH-20 column chromatography, a newly developed high pressure liquid chromatographic separation of hydrocarbon deoxyribonucleoside adducts derived from the DNA of mouse embryo cell cultures exposed to 7,12-dimethylbenz(a)anthracene (DMBA) provides markedly superior resolution. Once resolved, the fluorescence spectroscopic properties of the three major DMBA--DNA adducts indicate that the fluorescence exhibited by adducts derived from a bay region syn dihydrodiol epoxide of DMBA differs subtly from that exhibited by adducts derived from the isomeric anti dihydrodiol epoxide.

  12. A Gas Chromatograph/Mass Spectrometer System for UltraLow-Emission Combustor Exhaust Studies

    NASA Technical Reports Server (NTRS)

    Brabbs, Theodore A.; Wey, Chowen Chou

    1996-01-01

    A gas chromatograph (GC)/mass spectrometer (MS) system that allows the speciation of unburnt hydrocarbons in the combustor exhaust has been developed at the NASA Lewis Research Center. Combustion gas samples are withdrawn through a water-cooled sampling probe which, when not in use, is protected from contamination by a high-pressure nitrogen purge. The sample line and its connecting lines, filters, and valves are all ultraclean and are heated to avoid condensation. The system has resolution to the parts-per-billion (ppb) level.

  13. dc electrokinetic transport of cylindrical cells in straight microchannels

    PubMed Central

    Ai, Ye; Beskok, Ali; Gauthier, David T.; Joo, Sang W.; Qian, Shizhi

    2009-01-01

    Electrokinetic transport of cylindrical cells under dc electric fields in a straight microfluidic channel is experimentally and numerically investigated with emphasis on the dielectrophoretic (DEP) effect on their orientation variations. A two-dimensional multiphysics model, composed of the Navier–Stokes equations for the fluid flow and the Laplace equation for the electric potential defined in an arbitrary Lagrangian–Eulerian framework, is employed to capture the transient electrokinetic motion of cylindrical cells. The numerical predictions of the particle transport are in quantitative agreement with the obtained experimental results, suggesting that the DEP effect should be taken into account to study the electrokinetic transport of cylindrical particles even in a straight microchannel with uniform cross-sectional area. A comprehensive parametric study indicates that cylindrical particles would experience an oscillatory motion under low electric fields. However, they are aligned with their longest axis parallel to the imposed electric field under high electric fields due to the induced DEP effect. PMID:20216972

  14. Chromatographic and mass spectrometric techniques in studies on oxidative stress in autism.

    PubMed

    Kałużna-Czaplińska, Joanna; Jóźwik-Pruska, Jagoda

    2016-04-15

    Healthy body is characterized by the presence of a dynamic and balanced equilibrium between the production of reactive oxygen species (ROS) and the antioxidant capacity. In oxidative stress this balance is switched to reactions of oxidation leading to increased production of ROS, exceeding the capacity of physiological antioxidant systems. Oxidative stress is known to be linked to many disturbances, disorders and diseases. One of these is the autism spectrum disorder (ASD). ASD is a neurodevelopmental disorder manifested by abnormalities in social communication and interaction, as well as by occurrence of repetitive, restricted patterns of behavior or activities. It is believed that adequate knowledge about the oxidative stress biomarkers and the possibility of their reliable measuring could be useful in broadening knowledge on various diseases including ASD. A high number of compounds have been proposed as biomarkers of oxidative stress. Some of these are connected with the severity of ASD. The present review gives a summary of the chromatographic techniques used for the determination of biomarkers for oxidative stress in autism, and of other compounds important in this context. The first part of the review focuses on the correlation between oxidative stress and autism. The second part describes applications of chromatographic and mass spectrometric methods to the analysis of different metabolites connected with oxidative stress in biological fluids of autistic children. Advantages as well as disadvantages of the application of these methods for the analysis of different types of oxidative stress biomarkers are discussed.

  15. Comparative study of chromatographic medium-associated mass and potential antitumor activity loss with bioactive extracts.

    PubMed

    Datta, Sandipan; Zhou, Yu-Dong; Nagle, Dale G

    2013-04-26

    Natural product drug discovery programs often rely on the use of silica (Si) gel, reversed-phase media, or size-exclusion resins (e.g., RP-C18, Sephadex LH-20) for compound purification. The synthetic polymer-based sorbent Diaion HP20SS (cross-linked polystyrene matrix) is used as an alternative to prepare purified natural product libraries. To evaluate the impact of chromatographic media on the isolation of biologically active, yet chromatographically unstable natural products, Diaion HP20SS was evaluated side-by-side with normal-phase sorbents for irreversible binding of extract constituents and their effects on bioactivity. An array of chemically diverse natural product-rich extracts was selected as a test panel, and a cell-based reporter assay for hypoxia-inducible factor-1 (HIF-1) was employed to monitor potential change(s) in bioactivity. Silica gel caused significant irreversible binding of three out of 10 extracts. Curcuma longa, Saururus cernuus, and Citrus reticulata extracts showed decreased HIF-1 inhibitory activity after elution through Si gel. An additional nonpolar column wash of HP20SS with EtOAc retained considerable bioactivities of active extracts. In general, Si gel produced the greatest loss of bioactivity. However, HP20SS elution reduced significantly HIF-1 inhibitory activity of certain extracts (e.g., Asimina triloba). PMID:23441686

  16. Chromatographic methods for determination of S-substituted cysteine derivatives--a comparative study.

    PubMed

    Kubec, Roman; Dadáková, Eva

    2009-10-01

    A novel HPLC method for determination of a wide variety of S-substituted cysteine derivatives in Allium species has been developed and validated. This method allows simultaneous separation and quantification of S-alk(en)ylcysteine S-oxides, gamma-glutamyl-S-alk(en)ylcysteines and gamma-glutamyl-S-alk(en)ylcysteine S-oxides in a single run. The procedure is based on extraction of these amino acids and dipeptides by methanol, their derivatization by dansyl chloride and subsequent separation by reversed phase HPLC. The main advantages of the new method are simplicity, excellent stability of derivatives, high sensitivity, specificity and the ability to simultaneously analyze the whole range of S-substituted cysteine derivatives. This method was critically compared with other chromatographic procedures used for quantification of S-substituted cysteine derivatives, namely with two other HPLC methods (derivatization by o-phthaldialdehyde/tert-butylthiol and fluorenylmethyl chloroformate), and with determination by gas chromatography or capillary electrophoresis. Major advantages and drawbacks of these analytical procedures are discussed. Employing these various chromatographic methods, the content and relative proportions of individual S-substituted cysteine derivatives were determined in four most frequently consumed alliaceous vegetables (garlic, onion, shallot, and leek). PMID:19733357

  17. Electrokinetic remediation of fluorine-contaminated soil: conditioning of anolyte.

    PubMed

    Kim, Do-Hyung; Jeon, Chil-Sung; Baek, Kitae; Ko, Sung-Hwan; Yang, Jung-Seok

    2009-01-15

    The feasibility of anolyte conditioning on electrokinetic remediation of fluorine-contaminated soil was investigated with a field soil. The initial concentration of fluorine, pH and water content in the soil were 414mg/kg, 8.91 and 15%, respectively. Because the extraction of fluorine generally increased with the soil pH, the pH of the anode compartment was controlled by circulating strong alkaline solution to enhance the extraction of fluorine during electrokinetic remediation. The removal of fluorine increased with the concentration of the alkaline solution and applied current density and fluorine removed up to 75.6% within 14 days. Additionally, anolyte conditioning sharply increased the electro-osmotic flow, which enhanced the removal of fluorine in this study. In many respects, anolyte conditioning in electrokinetic remediation of fluorine-contaminated soil will be a promising technology.

  18. Comparative study of multi walled carbon nanotubes-based electrodes in micellar media and their application to micellar electrokinetic capillary chromatography.

    PubMed

    Chicharro, Manuel; Arribas, Alberto Sánchez; Moreno, Mónica; Bermejo, Esperanza; Zapardiel, Antonio

    2007-12-15

    This work reports on a comparative study of the electrochemical performance of carbon nanotubes-based electrodes in micellar media and their application for amperometric detection in micellar electrokinetic capillary chromatography (MEKC) separations. These electrodes were prepared in two different ways: immobilization of a layer of carbon nanotubes dispersed in polyethylenimine (PEI), ethanol or Nafion onto glassy carbon electrodes or preparation of paste electrodes using mineral oil as binder. Scanning electron microscopy (SEM) was employed for surface morphology characterization while cyclic voltammetry of background electrolyte was used for capacitance estimation. The amperometric responses to hydrogen peroxide, amitrol, diuron and 2,3-dichlorophenol (2,3CP) in the presence and in the absence of sodium dodecylsulphate (SDS) were studied by flow injection analysis (FIA), demonstrating that the electrocatalytic activity, background current and electroanalytical performance were strongly dependent on the electrodes preparation procedure. Glassy carbon electrodes modified with carbon nanotubes dispersed in PEI (GC/(CNT/PEI)) displayed the most adequate performance in micellar media, maintaining good electrocatalytic properties combined with acceptable background currents and resistance to passivation. The advantages of using GC/(CNT/PEI) as detectors in capillary electrophoresis were illustrated for the MEKC separations of phenolic pollutants (phenol, 3-chlorophenol, 2,3-dichlorophenol and 4-nitrophenol) and herbicides (amitrol, asulam, diuron, fenuron, monuron and chlortoluron).

  19. Numerical studies of continuous nutrient delivery for tumour spheroid culture in a microchannel by electrokinetically-induced pressure-driven flow.

    PubMed

    Movahed, Saeid; Li, Dongqing

    2010-12-01

    Continuous nutrient delivery to cells by pressure-driven flow is desirable for cell culture in lab-on-a-chip devices. An innovative method is proposed to generate an induced pressure-driven flow by using an electrokinetically-driven pump in a H-shape microchannel. A three-dimensional numerical model is developed to study the effectiveness of the proposed mechanism. It is shown that the average velocity of the generated pressure-driven flow is linearly dependent on the applied voltage. Considering the culture of a multicellular tumour spheroid (MTS) in such a microfluidic system, numerical simulations based on EMT6/Ro tumour cells is performed to find the effects of the nutrient distribution (oxygen and glucose), bulk velocity and channel size on the cell growth. Using an empirical formula, the growth of the tumour cell is studied. For low nutrient concentrations and low speed flows, it is found that the MTS grows faster in larger channels. It is also shown that, for low nutrient concentrations, a higher bulk liquid velocity provide better environment for MTS to grow. For lower velocities, it is found that the local MTS growth along the flow direction deviates from the average growth. PMID:20689992

  20. Current Applications of Chromatographic Methods in the Study of Human Body Fluids for Diagnosing Disorders.

    PubMed

    Jóźwik, Jagoda; Kałużna-Czaplińska, Joanna

    2016-01-01

    Currently, analysis of various human body fluids is one of the most essential and promising approaches to enable the discovery of biomarkers or pathophysiological mechanisms for disorders and diseases. Analysis of these fluids is challenging due to their complex composition and unique characteristics. Development of new analytical methods in this field has made it possible to analyze body fluids with higher selectivity, sensitivity, and precision. The composition and concentration of analytes in body fluids are most often determined by chromatography-based techniques. There is no doubt that proper use of knowledge that comes from a better understanding of the role of body fluids requires the cooperation of scientists of diverse specializations, including analytical chemists, biologists, and physicians. This article summarizes current knowledge about the application of different chromatographic methods in analyses of a wide range of compounds in human body fluids in order to diagnose certain diseases and disorders.

  1. Comparative study of two chromatographic columns used in the GLC determination of methylmercury

    SciTech Connect

    Najdek, M.; Bazulic, D.

    1985-02-01

    A large effort has gone into finding an adequate analytical method for the determinations of methylmercury. Various stationary phases in GC determination have been tested. It was obvious with every method that the stationary phase had to be saturated to give a stable response without tailing the peaks or walking the retention time. To accomplish this several authors have reported treatments which included the injection of the solutions containing inorganic or organic mercuric chloride metoxyethylmercuric iodide, or large amount of potassium iodide. The authors report here a simple and efficient way to obtain satisfactory stable response from the chromatographic column based on the use of 10% diethyleneglycol adipate (DEGA) and 3% polyethyleneglycol (Carbowax 20 M).

  2. New supervised alignment method as a preprocessing tool for chromatographic data in metabolomic studies.

    PubMed

    Struck, Wiktoria; Wiczling, Paweł; Waszczuk-Jankowska, Małgorzata; Kaliszan, Roman; Markuszewski, Michał Jan

    2012-09-21

    The purpose of this work was to develop a new aligning algorithm called supervised alignment and to compare its performance with the correlation optimized warping. The supervised alignment is based on a "supervised" selection of a few common peaks presented on each chromatogram. The selected peaks are aligned based on a difference in the retention time of the selected analytes in the sample and the reference chromatogram. The retention times of the fragments between known peaks are subsequently linearly interpolated. The performance of the proposed algorithm has been tested on a series of simulated and experimental chromatograms. The simulated chromatograms comprised analytes with a systematic or random retention time shifts. The experimental chromatographic (RP-HPLC) data have been obtained during the analysis of nucleosides from 208 urine samples and consists of both the systematic and random displacements. All the data sets have been aligned using the correlation optimized warping and the supervised alignment. The time required to complete the alignment, the overall complexity of both algorithms, and its performance measured by the average correlation coefficients are compared to assess performance of tested methods. In the case of systematic shifts, both methods lead to the successful alignment. However, for random shifts, the correlation optimized warping in comparison to the supervised alignment requires more time (few hours versus few minutes) and the quality of the alignment described as correlation coefficient of the newly aligned matrix is worse 0.8593 versus 0.9629. For the experimental dataset supervised alignment successfully aligns 208 samples using 10 prior identified peaks. The knowledge about retention times of few analytes' in the data sets is necessary to perform the supervised alignment for both systematic and random shifts. The supervised alignment method is faster, more effective and simpler preprocessing method than the correlation optimized

  3. Electrokinetic high pressure hydraulic system

    DOEpatents

    Paul, Phillip H.; Rakestraw, David J.

    2000-01-01

    A compact high pressure hydraulic pump having no moving mechanical parts for converting electric potential to hydraulic force. The electrokinetic pump, which can generate hydraulic pressures greater than 2500 psi, can be employed to compress a fluid, either liquid or gas, and manipulate fluid flow. The pump is particularly useful for capillary-base systems. By combining the electrokinetic pump with a housing having chambers separated by a flexible member, fluid flow, including high pressure fluids, is controlled by the application of an electric potential, that can vary with time.

  4. Electrokinetics of isolated electrified drops.

    PubMed

    Pillai, Rohit; Berry, Joseph D; Harvie, Dalton J E; Davidson, Malcolm R

    2016-04-14

    Using a recently developed multiphase electrokinetic model, we simulate the transient electrohydrodynamic response of a liquid drop containing ions, to both small and large values of electric field. The temporal evolution is found to be governed primarily by two dimensionless groups: (i) Ohnesorge number (Oh), a ratio of viscous to inertio-capillary effects, and (ii) inverse dimensionless Debye length (κ), a measure of the diffuse regions of charge that develop in the drop. The effects of dielectric polarization dominate at low Oh, while effects of separated charge gain importance with increase in Oh. For small values of electric field, the deformation behaviour of a drop is shown to be accurately described by a simple analytical expression. At large electric fields, the drops are unstable and eject progeny drops. Depending on Oh and κ this occurs via dripping or jetting; the regime transitions are shown by a Oh-κ phase map. In contrast to previous studies, we find universal scaling relations to predict size and charge of progeny drops. Our simulations suggest charge transport plays a significant role in drop dynamics for 0.1 ≤ Oh ≤ 10, a parameter range of interest in microscale flows.

  5. Determination of polynuclear aromatic hydrocarbons (PAHs) in sewage sludge by micellar electrokinetic capillary chromatography and HPLC-fluorescence detection: a comparative study.

    PubMed

    Alzola, R; Pons, B; Bravo, D; Arranz, A

    2008-11-01

    Two different methods, based on micellar electrokinetic capillary chromatography (MECC-DA) and high performance liquid chromatography (HPLC)-fluorescence detection, were studied to separate and determine 12 polynuclear aromatic hydrocarbons (PAHs) of 16 PAHs recommended by the Environmental Protection Agency (EPA) in sewage sludge. beta-cyclodextrin was used as a micelle precursor in a sodium borate buffer solution which included the surfactant sodium dodecyl sulphate (SDS) and the acetonitrile dissolvent. The following parameters: temperature, voltage, pH, concentrations of buffer solution and injection time, were optimized by an experimental design (Nemrodw programme). Furthermore, HPLC-fluorescence detection and separation conditions are reported. The mobile phase was acetonitrile-water in different percentages. Precision, accuracy, linearity and detection and quantification limits were determined. This method was applied in the analysis of sewage sludge from a wastewater depuration station in Crispijana (Alava, Spain). In this case, it is necessary to carry out a solid phase extraction step for its determination. The method was validated by the analysis of a certificated sample of LGC 6182, and finally samples of sewage sludge were analysed weekly for two years, obtaining in all cases results under the legal limits for the use of sewage sludge in agriculture.

  6. Electrokinetic remediation of oil-contaminated soils.

    PubMed

    Korolev, Vladimir A; Romanyukha, Olga V; Abyzova, Anna M

    2008-07-01

    This investigation was undertaken to determine the factors influencing electrokinetic remediation of soils from petroleum pollutants. The remediation method was applied in two versions: (i) static and (ii) flowing, when a sample was washed with leaching solution. It was found that all the soils studied can be purified using this technique. It was also observed that the mineral and grain-size composition of soils, their properties, and other parameters affect the remediation efficiency. The static and flowing versions of the remediation method removed 25-75% and 90-95% of the petroleum pollutants, respectively from the soils under study.

  7. Chromatographic analysis of some drugs employed in erectile dysfunction therapy: qualitative and quantitative studies using calixarene stationary phase.

    PubMed

    Hashem, Hisham; Ibrahim, Adel Ehab; Elhenawee, Magda

    2014-10-01

    In this study, the effect of change in chromatographic process variables on the retention behavior of four drugs employed in erectile dysfunction therapy on a calixarene stationary phase is described. Three of these drugs are known to treat erectile dysfunction, namely, sildenafil citrate, tadalafil, and apomorphine hydrochloride, and one drug that is used as opioid analgesic, tramadol hydrochloride, which is quiet widely misused to treat premature ejaculation. The results indicate the importance of considering the structure and pKa values of drugs to be separated along with mobile phase composition. A new optimized, rapid, and accurate liquid chromatography method is also established for simultaneous determination of sildenafil citrate, tadalafil, and apomorphine hydrochloride in pharmaceutical preparations and bulk powders. The chromatographic separation of the three pharmaceuticals was achieved on a calixarene column in less than 10 min using a binary mobile phase of 35% acetonitrile and 65% 50 mM sodium perchlorate pH2.5 at 1 mL/min flow rate. The method was validated for system efficiency, linearity, accuracy, precision, limits of detection and quantitation, specificity, stability, and robustness. Statistical analysis proved that the method enabled reproducible and selective quantification of all three analytes in bulk drugs and in pharmaceutical preparations.

  8. Electrokinetically pumped high pressure sprays

    DOEpatents

    Schoeniger, Joseph S.; Paul, Phillip H.; Schoeniger, Luke

    2005-11-01

    An electrokinetic pump capable of producing high pressure is combined with a nozzle having a submicron orifice to provide a high pressure spray device. Because of its small size, the device can be contained within medical devices such as an endoscope for delivering biological materials such as DNA, chemo therapeutic agents, or vaccines to tissues and cells.

  9. Electrokinetically pumped high pressure sprays

    SciTech Connect

    Schoeniger, Joseph S.; Paul, Phillip H.; Schoeniger, Luke

    2002-01-01

    An electrokinetic pump capable of producing high pressure is combined with a nozzle having a submicron orifice to provide a high pressure spray device. Because of its small size, the device can be contained within medical devices such as an endoscope for delivering biological materials such as DNA, chemo therapeutic agents, or vaccines to tissues and cells.

  10. Qualification of an electro-deionization module via experimental design and ion-chromatographic studies.

    PubMed

    Castillo, Elodie; Coleman, David E; Darbouret, Daniel; Dimitrakopoulos, Telis; Feuillas, Emmanuel; Vanatta, Lynn E

    2004-06-11

    To meet the needs of the laboratory-water market, a modified electro-deionization (EDI) module has been developed to produce Type 2 purified water. An EDI module consists of desalting and concentrating fluidic compartments that are both filled with anion and cation ion-exchange resins; an anode and a cathode electrode are at opposite ends. In the design in this research, the anode electrode is segmented into three parts and individual dc amperages are applied to each segment; the cathode electrode is a single common electrode. Critical to the performance and longevity of this type of EDI module are: (1) the optimization of the applied dc amperages and (2) the ionic mass balance (i.e., the concentrations of specific and total ions of the RO feedwater to the module compared to the concentrations in the water exiting the module via the desalting and concentrating compartments). To determine a suitable current for each electrode pair, a full-factorial experimental design was developed and employed. For the application of this combination of amperages, the critical parameter of specific-ion mass balance was determined using ion-chromatographic measurements. PMID:15250404

  11. Chromatographic and mass spectral studies on methoxy methyl methamphetamines related to 3,4-methylenedioxymethamphetamine.

    PubMed

    Awad, Tamer; Deruiter, Jack; Clark, C Randall

    2007-09-01

    The methoxy methyl methamphetamines are a unique set of compounds having an isobaric relationship with the controlled drug substance 3,4-methylenedioxymethamphetamine (3,4-MDMA or Ecstasy). The various isomeric forms of the methoxy methyl methamphetamines have mass spectra essentially equivalent to 3,4-MDMA, all have molecular weight of 193 and major fragment ions in their electron ionization mass spectra at m/z 58 and 135/136. Mass spectral differentiation of 3,4-MDMA from some of the methoxy methyl methamphetamines was possible after formation of the perfluoroacyl derivatives, pentafluoropropionamides (PFPA) and heptafluorobutyramides (HFBA). Perfluoroacyl derivatization provided unique and characteristic mass spectral fragment ions when the methoxy group is substituted at the 2- or 4-position of the aromatic ring relative to the alkylamine side chain group. Perfluoroacyl derivatization did not offer any characteristic ions for discrimination of 3,4-MDMA from the 3-methoxy ring substituted methyl methamphetamines. Gas chromatographic separation on non-polar stationary phases successfully resolved subsets of the methoxy methyl methamphetamines, based on ring position of the methoxy group, from 2,3- and 3,4-MDMA as the PFPA and HFBA derivatives.

  12. Demonstration/field study of new designs of automated gas chromatographs in Connecticut and other locations, 1992. Final report

    SciTech Connect

    Holdren, M.W.; Smith, D.L.; Pollack, A.J.; Pate, A.D.

    1993-02-01

    The objectives of the study were to install, test and demonstrate two automated gas chromatographic (GC) systems to state and regional EPA groups. The Dynatherm/Hewlett Packard GC system was designed for the measurement of the 41 toxic compounds listed in EPA's Compendium of Methods for Method TO-14. The second system was a Perkin Elmer GC configured for the analysis of the 55 ozone precursor compounds identified in the EPA Technical Assistance Document No. EPA/600-8-91/215. Both GC systems performed well during the field evaluations with data capture of 98 percent. A method quantitation limit (MQL) of 0.5 ppbv was obtained for most of the target compounds. In examining daily control check runs, the variation of corrected GC retention times for each instrument and detector ranged from 0.023 to 0.044 minutes.

  13. Hybrid continuum-atomistic approach to model electrokinetics in nanofluidics.

    PubMed

    Amani, Ehsan; Movahed, Saeid

    2016-06-01

    In this study, for the first time, a hybrid continuum-atomistic based model is proposed for electrokinetics, electroosmosis and electrophoresis, through nanochannels. Although continuum based methods are accurate enough to model fluid flow and electric potential in nanofluidics (in dimensions larger than 4 nm), ionic concentration is too low in nanochannels for the continuum assumption to be valid. On the other hand, the non-continuum based approaches are too time-consuming and therefore is limited to simple geometries, in practice. Here, to propose an efficient hybrid continuum-atomistic method of modelling the electrokinetics in nanochannels; the fluid flow and electric potential are computed based on continuum hypothesis coupled with an atomistic Lagrangian approach for the ionic transport. The results of the model are compared to and validated by the results of the molecular dynamics technique for a couple of case studies. Then, the influences of bulk ionic concentration, external electric field, size of nanochannel, and surface electric charge on the electrokinetic flow and ionic mass transfer are investigated, carefully. The hybrid continuum-atomistic method is a promising approach to model more complicated geometries and investigate more details of the electrokinetics in nanofluidics. PMID:27155300

  14. Study of the mechanism of acetonitrile stacking and its application for directly combining liquid-phase microextraction with micellar electrokinetic chromatography.

    PubMed

    Sun, Jingru; Feng, Jing; Shi, Ludi; Liu, Laping; He, Hui; Fan, Yingying; Hu, Shibin; Liu, Shuhui

    2016-08-26

    Acetonitrile stacking is an online concentration method that is distinctive due to its inclusion of a high proportion of organic solvent in sample matrices. We previously designed a universal methodology for the combination of liquid-phase microextraction (LPME) and capillary electrophoresis (CE) using acetonitrile stacking and micellar electrokinetic chromatography (MEKC) mode, thereby achieving large-volume injection of the diluted LPME extractant and the online concentration. In this report, the methodology was extended to the analysis of highly substituted hydrophobic chlorophenols in wines using diethyl carbonate as the extractant. Additionally, the mechanism of acetonitrile stacking was studied. The results indicated that the combination of LPME and MEKC exhibited good analytical performance: with ∼40-fold concentration by LPME, a 20-cm (33% of the total length) sample plug injection of an eight-fold dilution of diethyl carbonate with the organic solvent-saline solution produced enrichments higher by a factor of 260-791. Limits of qualification ranged from 5.5 to 16.0ng/mL. Acceptable reproducibilities of lower than 1.8% for migration time and 8.6% for peak areas were obtained. A dual stacking mechanism of acetonitrile stacking was revealed, involving transient isotachophoresis plus pH-junction stacking. The latter was associated with a pH shift induced by the presence of acetonitrile. The pseudo-stationary phase (Brij-35) played an important role in reducing the CE running time by weakening the isotachophoretic migration of the analyte ions following Cl(-) ions. The combination of acetonitrile stacking and nonionic micelle-based MEKC appears to be a perfect match for introducing water-immiscible LPME extractants into an aqueous CE system and can thus significantly expand the application of LPME-CE in green analytical chemistry. PMID:27451260

  15. Study of the mechanism of acetonitrile stacking and its application for directly combining liquid-phase microextraction with micellar electrokinetic chromatography.

    PubMed

    Sun, Jingru; Feng, Jing; Shi, Ludi; Liu, Laping; He, Hui; Fan, Yingying; Hu, Shibin; Liu, Shuhui

    2016-08-26

    Acetonitrile stacking is an online concentration method that is distinctive due to its inclusion of a high proportion of organic solvent in sample matrices. We previously designed a universal methodology for the combination of liquid-phase microextraction (LPME) and capillary electrophoresis (CE) using acetonitrile stacking and micellar electrokinetic chromatography (MEKC) mode, thereby achieving large-volume injection of the diluted LPME extractant and the online concentration. In this report, the methodology was extended to the analysis of highly substituted hydrophobic chlorophenols in wines using diethyl carbonate as the extractant. Additionally, the mechanism of acetonitrile stacking was studied. The results indicated that the combination of LPME and MEKC exhibited good analytical performance: with ∼40-fold concentration by LPME, a 20-cm (33% of the total length) sample plug injection of an eight-fold dilution of diethyl carbonate with the organic solvent-saline solution produced enrichments higher by a factor of 260-791. Limits of qualification ranged from 5.5 to 16.0ng/mL. Acceptable reproducibilities of lower than 1.8% for migration time and 8.6% for peak areas were obtained. A dual stacking mechanism of acetonitrile stacking was revealed, involving transient isotachophoresis plus pH-junction stacking. The latter was associated with a pH shift induced by the presence of acetonitrile. The pseudo-stationary phase (Brij-35) played an important role in reducing the CE running time by weakening the isotachophoretic migration of the analyte ions following Cl(-) ions. The combination of acetonitrile stacking and nonionic micelle-based MEKC appears to be a perfect match for introducing water-immiscible LPME extractants into an aqueous CE system and can thus significantly expand the application of LPME-CE in green analytical chemistry.

  16. [Anolyte enhanced electrokinetic remediation of fluorine-contaminated soils].

    PubMed

    Zhu, Shu-Fa; Yan, Chun-Li; Dong, Tie-You; Tang, Hong-Yan

    2009-07-15

    An experimental study was carried out in order to determine the characteristics of migration and its influencing factor of soil fluorine in the electrokinetic process under different applied voltage and concentration of anolyte. The feasibility of anolyte enhanced on electrokinetic remediation of fluorine-contaminated soil was analyzed. The results show that when deionized water is used as anolyte with the 1.0 V/cm voltage gradient, the cumulative mass of fluorine in catholyte and anolyte are 8.2 mg and 47.7 mg respectively and the removal rate of fluorine is only 8.8%. Anolyte enhanced electrokinetic process can promote effectively the migration of fluoride in soil. When 0.02 mol/L NaOH solutionis employed as the anolyte, the removal rates are 25.9%, 31.2% and 47.3% with 1.0, 1.5 and 2.0 V/cm voltage gradient respectively. As the concentration of anolyte increased to 0.1 mol/L, the removal rates are 55.4%, 61.1% and 73.0%. The electromigration is the main transport mechanism and the electroosmotic flow has an effect on the migration of fluorine in soil. The voltage gradient and the concentration of anolyte are the main factors influencing the removal rate of fluorine in soil. Appropriate anolyte enhanced electrokinetic method can be applied to remediate fluorine from contaminated soil.

  17. Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column

    NASA Technical Reports Server (NTRS)

    Huz, Kateryna

    2014-01-01

    RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better

  18. Effects of electrokinetics and cationic surfactant cetyltrimethylammonium bromide [CTAB] on the hydrocarbon removal and retention from contaminated soils.

    PubMed

    Ranjan, R Sri; Qian, Y; Krishnapillai, M

    2006-07-01

    Hydrocarbon contaminated soil and groundwater is considered to be a leading cause for increased health risk and environmental contamination. Therefore, an efficient technique is needed to retard the movement or enhance the removal of the contaminant depending on the remediation objective. The goals of this study were to evaluate the impact of the addition of a cationic surfactant on the movement of hydrocarbons within a contaminated clay soil subjected to electrokinetic treatment. Water-flushing and surfactant-flushing experiments were conducted on one-dimensional soil columns. The model diesel fuel was composed of a mixture of benzene, toluene, ethylbenzene, xylenes [BTEX] and three selected polycyclic hydrocarbons [PAHs]. In the water-flushing experiments, the application of an electrokinetic treatment was found to enhance the removal of PAHs from the clay columns by about 20%. In contrast, the application of an electrokinetic treatment, when coupled with cationic surfactant-flushing, retarded the movement of BTEX and the three selected PAHs in the clay columns. Hydraulic columns with surfactant (CTAB) removed 17% more naphthalene and 11% more 2-methylnaphthalene compared to columns subjected to electrokinetic treatment with CTAB. The flux through the electrokinetic columns during water flushing as well as surfactant flushing was higher than the flux due to hydraulic gradient alone. As the solubility of hydrocarbons increased, they moved farther with electrokinetic treatment without CTAB. However, with CTAB the electrokinetic treatment tends to retard the movement. Use of a cationic surfactant coupled with electrokinetic treatment was found to retard the movement of contaminants.

  19. Electrokinetic high pressure hydraulic system

    DOEpatents

    Paul, Phillip H.; Rakestraw, David J.; Arnold, Don W.; Hencken, Kenneth R.; Schoeniger, Joseph S.; Neyer, David W.

    2003-06-03

    An electrokinetic high pressure hydraulic pump for manipulating fluids in capillary-based system. The pump uses electro-osmotic flow to provide a high pressure hydraulic system, having no moving mechanical parts, for pumping and/or compressing fluids, for providing valve means and means for opening and closing valves, for controlling fluid flow rate, and manipulating fluid flow generally and in capillary-based systems (microsystems), in particular. The compact nature of the inventive high pressure hydraulic pump provides the ability to construct a micro-scale or capillary-based HPLC system that fulfills the desire for small sample quantity, low solvent consumption, improved efficiency, the ability to run samples in parallel, and field portability. Control of pressure and solvent flow rate is achieved by controlling the voltage applied to an electrokinetic pump.

  20. Electrokinetic high pressure hydraulic system

    DOEpatents

    Paul, Phillip H.; Rakestraw, David J.; Arnold, Don W.; Hencken, Kenneth R.; Schoeniger, Joseph S.; Neyer, David W.

    2001-01-01

    An electrokinetic high pressure hydraulic pump for manipulating fluids in capillary-based systems. The pump uses electro-osmotic flow to provide a high pressure hydraulic system, having no moving mechanical parts, for pumping and/or compressing fluids, for providing valve means and means for opening and closing valves, for controlling fluid flow rate, and manipulating fluid flow generally and in capillary-based systems (Microsystems), in particular. The compact nature of the inventive high pressure hydraulic pump provides the ability to construct a micro-scale or capillary-based HPLC system that fulfills the desire for small sample quantity, low solvent consumption, improved efficiency, the ability to run samples in parallel, and field portability. Control of pressure and solvent flow rate is achieved by controlling the voltage applied to an electrokinetic pump.

  1. Thin-layer chromatographic analysis of myelin lipids, their differential O-deacylation by primary alkylamines and their selective staining by thionine. A limited phylogenetic study.

    PubMed

    Hack, M H; Helmy, F M

    1990-02-23

    A silica gel thin-layer chromatographic procedure is described for the study of the myelin lipid patterns in a small phylogenetic series of nerve tissue specimens. It involves the selective staining by the thiazine dye thionine and the interpretations were facilitated by a preceding primary alkylamine O-deacylation step. Glycolipids, including sulfatides, and ethanolamine plasmalogens were the principal characterizing lipids.

  2. INTERLABORATORY STUDY OF A THERMOSPRAY-LIQUID CHROMATOGRAPHIC/MASS SPECTROMETRIC METHOD FOR SELECTED N-METHYL CARBAMATES, N-METHYL CARBAMOYLOXIMES, AND SUBSTITUTED UREA PESTICIDES

    EPA Science Inventory

    A thermospray-liquid chromatographic/mass spectrometric (TS-LC/MS) method was evaluated in an interlaboratory study for determining 3 N-methyl carbamates (bendiocarb, carbaryl, and carbofuran), 3-N-methyl carbamoyloximes (aldicarb, methomyl, and oxamyl), 2 substituted urea pestic...

  3. Pseudo 1-D Micro/Nanofluidic Device for Exact Electrokinetic Responses.

    PubMed

    Kim, Junsuk; Kim, Ho-Young; Lee, Hyomin; Kim, Sung Jae

    2016-06-28

    Conventionally, a 1-D micro/nanofluidic device, whose nanochannel bridged two microchannels, was widely chosen in the fundamental electrokinetic studies; however, the configuration had intrinsic limitations of the time-consuming and labor intensive tasks of filling and flushing the microchannel due to the high fluidic resistance of the nanochannel bridge. In this work, a pseudo 1-D micro/nanofluidic device incorporating air valves at each microchannel was proposed for mitigating these limitations. High Laplace pressure formed at liquid/air interface inside the microchannels played as a virtual valve only when the electrokinetic operations were conducted. The identical electrokinetic behaviors of the propagation of ion concentration polarization layer and current-voltage responses were obtained in comparison with the conventional 1-D micro/nanofluidic device by both experiments and numerical simulations. Therefore, the suggested pseudo 1-D micro/nanofluidic device owned not only experimental conveniences but also exact electrokinetic responses. PMID:27248856

  4. REMOVAL OF RADIONUCLIDES BY ELECTROKINETIC SOIL PROCESSING

    EPA Science Inventory

    Electrokinetics promises to be an innovative treatment process for in-situ treatment of soils and groundwater contaminated with heavy metals and radionuclides. Electrokinetics refers to the movement of ionic liquids and charged particles relative to one another under the action ...

  5. Lysozyme adsorption onto a cation-exchanger: mechanism of interaction study based on the analysis of retention chromatographic data.

    PubMed

    Marques, F S; Silva, G L; Thrash, M E; Dias-Cabral, A C

    2014-10-01

    In this study, based on the analysis of retention chromatographic data, we examined the adsorption of lysozyme onto carboxymethyl cellulose. Lysozyme retention data was collected at pH 5 and pH 8. The sodium chloride (NaCl) concentration in the mobile phase ranged from 300mM to 500mM and the temperature for this study varied from 288K to 308K. The retention measurements generated from these experimental conditions were analyzed with the Van't Hoff method, the preferential interaction model and the stoichiometric displacement model. Endothermic heats-of-adsorption and increases in entropy were observed under certain experimental conditions. These data suggest the presence of entropic driving forces such as the release of water and/or possibly structural changes in lysozyme molecules adsorbed to the surface of carboxymethyl cellulose. The modest observed exergonic adsorption ΔG° and the preferential interaction analysis corroborate the presence of water-release for this study. Additional analysis with the stoichiometric displacement model method revealed negligible changes in the structure of lysozyme molecules in contact with the surface of carboxymethyl cellulose. PMID:25193151

  6. Effect of electrokinetic remediation on indigenous microbial activity and community within diesel contaminated soil.

    PubMed

    Kim, Seong-Hye; Han, Hyo-Yeol; Lee, You-Jin; Kim, Chul Woong; Yang, Ji-Won

    2010-07-15

    Electrokinetic remediation has been successfully used to remove organic contaminants and heavy metals within soil. The electrokinetic process changes basic soil properties, but little is known about the impact of this remediation technology on indigenous soil microbial activities. This study reports on the effects of electrokinetic remediation on indigenous microbial activity and community within diesel contaminated soil. The main removal mechanism of diesel was electroosmosis and most of the bacteria were transported by electroosmosis. After 25 days of electrokinetic remediation (0.63 mA cm(-2)), soil pH developed from pH 3.5 near the anode to pH 10.8 near the cathode. The soil pH change by electrokinetics reduced microbial cell number and microbial diversity. Especially the number of culturable bacteria decreased significantly and only Bacillus and strains in Bacillales were found as culturable bacteria. The use of EDTA as an electrolyte seemed to have detrimental effects on the soil microbial activity, particularly in the soil near the cathode. On the other hand, the soil dehydrogenase activity was enhanced close to the anode and the analysis of microbial community structure showed the increase of several microbial populations after electrokinetics. It is thought that the main causes of changes in microbial activities were soil pH and direct electric current. The results described here suggest that the application of electrokinetics can be a promising soil remediation technology if soil parameters, electric current, and electrolyte are suitably controlled based on the understanding of interaction between electrokinetics, contaminants, and indigenous microbial community. PMID:20452646

  7. Geochemical reconnaissance of heavy metals in kaolin after electrokinetic remediation.

    PubMed

    Al-Hamdan, Ashraf Z; Reddy, Krishna R

    2006-01-01

    The development or implementation of electrokinetic soil remediation technique requires a good knowledge of how the contaminants are retained within the soil-water system. This paper investigates the speciation and extent of migration of the heavy metals, Cr(VI), Cr(III), Ni(II), and Cd(II), during electrokinetic soil remediation. A geochemical assessment of how the contaminants are held within the kaolin soil under induced electric potential is made by using the equilibrium model MINEQL+. The study is performed for three different contaminant cases: the Cr(VI) existing alone in the soil, the Cr(VI) combined with Ni(II) and Cd(II) in the soil, and the Cr(VI) combined with Ni(II) and Cd(II) in the soil in the presence of a reducing agent (sulfide). The adsorption of the studied metals by kaolin was implemented as an electrostatic behavior. FITEQL 4.0 model was used to determine the equilibrium constants of the electrostatic adsorption model of kaolin for the studied metals by optimizing the experimental titration and adsorption data of kaolin. This study showed that the initial speciation of the contaminants in the soil prior to the electrokinetic treatment depends on the type and amounts of contaminants present as well as on the presence of the co-contaminants or any reducing agent. Moreover, the extent of migration of the contaminants is strongly dependent on their initial speciation prior electrokinetic treatment. This study also showed that adsorption and precipitation are the significant hindering mechanisms for the removal of heavy metals from kaolin soil during electrokinetic treatment. The adsorption and precipitation forms of Cr(III), Ni(II), and Cd(II) increased near the cathode and decreased near the anode, whereas the adsorption form of Cr(VI) increased near the anode as well as in the middle region. However, the precipitation form of Cr(III), Ni(II), and Cd(II) as Cr2O3 or Cr(OH)3, Ni(OH)2, and Cd(OH)2, respectively, dominates over their adsorption form

  8. Comparative study of different chromatographic techniques for the analysis of multi-residues of some approved antimicrobials in fish tissues.

    PubMed

    Riad, Safa'a M; Rezk, Mamdouh R; Khattab, Fatma I; Marzouk, Hoda M

    2015-01-01

    Two chromatographic methods were developed, optimized and validated for the simultaneous determination of three approved aquaculture antimicrobials, namely sulphadimethoxine sodium, trimethoprim and florphenicol in fish tissues. The developed methods were based on simple liquid extraction technique. The first method employs thin-layer chromatography as a clean-up procedure coupled with densitometric determination for the separated drugs. The second method is an HPLC one using X-Terra™ C18 column. Several mobile-phase systems and extracting solvents were tried to optimize the separation and the extraction procedures from fish tissues. The procedures were applied for the analysis of spiked fish tissue samples at three different concentration levels (10, 50 and 100 ppm). A comparative study was conducted between the proposed methods to discuss the advantage of each one. The methods were validated according to the international conference on harmonization guidelines. The proposed methods were successfully applied for the determination of the studied drugs in spiked fish tissues, pure powders and in their veterinary pharmaceutical formulation.

  9. Electrokinetic remediation of fluorine-contaminated soil and its impact on soil fertility.

    PubMed

    Zhou, Ming; Wang, Hui; Zhu, Shufa; Liu, Yana; Xu, Jingming

    2015-11-01

    Compared to soil pollution by heavy metals and organic pollutants, soil pollution by fluorides is usually ignored in China. Actually, fluorine-contaminated soil has an unfavorable influence on human, animals, plants, and surrounding environment. This study reports on electrokinetic remediation of fluorine-contaminated soil and the effects of this remediation technology on soil fertility. Experimental results showed that electrokinetic remediation using NaOH as the anolyte was a considerable choice to eliminate fluorine in contaminated soils. Under the experimental conditions, the removal efficiency of fluorine by the electrokinetic remediation method was 70.35%. However, the electrokinetic remediation had a significant impact on the distribution and concentrations of soil native compounds. After the electrokinetic experiment, in the treated soil, the average value of available nitrogen was raised from 69.53 to 74.23 mg/kg, the average value of available phosphorus and potassium were reduced from 20.05 to 10.39 mg/kg and from 61.31 to 51.58 mg/kg, respectively. Meanwhile, the contents of soil available nitrogen and phosphorus in the anode regions were higher than those in the cathode regions, but the distribution of soil available potassium was just the opposite. In soil organic matter, there was no significant change. These experiment results suggested that some steps should be taken to offset the impacts, after electrokinetic treatment.

  10. Electrokinetic remediation of fluorine-contaminated soil and its impact on soil fertility.

    PubMed

    Zhou, Ming; Wang, Hui; Zhu, Shufa; Liu, Yana; Xu, Jingming

    2015-11-01

    Compared to soil pollution by heavy metals and organic pollutants, soil pollution by fluorides is usually ignored in China. Actually, fluorine-contaminated soil has an unfavorable influence on human, animals, plants, and surrounding environment. This study reports on electrokinetic remediation of fluorine-contaminated soil and the effects of this remediation technology on soil fertility. Experimental results showed that electrokinetic remediation using NaOH as the anolyte was a considerable choice to eliminate fluorine in contaminated soils. Under the experimental conditions, the removal efficiency of fluorine by the electrokinetic remediation method was 70.35%. However, the electrokinetic remediation had a significant impact on the distribution and concentrations of soil native compounds. After the electrokinetic experiment, in the treated soil, the average value of available nitrogen was raised from 69.53 to 74.23 mg/kg, the average value of available phosphorus and potassium were reduced from 20.05 to 10.39 mg/kg and from 61.31 to 51.58 mg/kg, respectively. Meanwhile, the contents of soil available nitrogen and phosphorus in the anode regions were higher than those in the cathode regions, but the distribution of soil available potassium was just the opposite. In soil organic matter, there was no significant change. These experiment results suggested that some steps should be taken to offset the impacts, after electrokinetic treatment. PMID:26109225

  11. Fuzzy C-means clustering for chromatographic fingerprints analysis: A gas chromatography-mass spectrometry case study.

    PubMed

    Parastar, Hadi; Bazrafshan, Alisina

    2016-03-18

    Fuzzy C-means clustering (FCM) is proposed as a promising method for the clustering of chromatographic fingerprints of complex samples, such as essential oils. As an example, secondary metabolites of 14 citrus leaves samples are extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The obtained chromatographic fingerprints are divided to desired number of chromatographic regions. Owing to the fact that chromatographic problems, such as elution time shift and peak overlap can significantly affect the clustering results, therefore, each chromatographic region is analyzed using multivariate curve resolution-alternating least squares (MCR-ALS) to address these problems. Then, the resolved elution profiles are used to make a new data matrix based on peak areas of pure components to cluster by FCM. The FCM clustering parameters (i.e., fuzziness coefficient and number of cluster) are optimized by two different methods of partial least squares (PLS) as a conventional method and minimization of FCM objective function as our new idea. The results showed that minimization of FCM objective function is an easier and better way to optimize FCM clustering parameters. Then, the optimized FCM clustering algorithm is used to cluster samples and variables to figure out the similarities and dissimilarities among samples and to find discriminant secondary metabolites in each cluster (chemotype). Finally, the FCM clustering results are compared with those of principal component analysis (PCA), hierarchical cluster analysis (HCA) and Kohonon maps. The results confirmed the outperformance of FCM over the frequently used clustering algorithms.

  12. High-performance liquid chromatographic method for the quantification of Mitragyna inermis alkaloids in order to perform pharmacokinetic studies.

    PubMed

    Sinou, Veronique; Fiot, Julien; Taudon, Nicolas; Mosnier, Joël; Martelloni, Maryse; Bun, Sok S; Parzy, Daniel; Ollivier, Evelyne

    2010-06-01

    In Africa, Mitragyna inermis (Willd.) O. Kuntze (Rubiaceae) is commonly used in traditional medicine to treat malaria. Antimalarial activity is mostly due to the hydromethanolic extract of M. inermis leaves and especially to the main alkaloids, uncarine D and isorhynchophilline. In the present study, we describe for the first time an HPLC method for the simultaneous quantification of uncarine D and isorhynchophylline in biological matrices. SPE was used to extract the components and the internal standard naphthalene from human and pig plasma samples. Chromatographic separation was performed on a C-18 reversed column at a flow rate of 1 mL/min, using methanol-phosphate buffer (10:90, pH 7), as a mobile phase. Good linearity was observed over the concentration ranges of 0.0662-3.31 microg/mL for uncarine D and 0.0476-2.38 microg/mL for isorynchophylline. The precision was less than 12% and the accuracy was from 86 to 107% without any discrepancy between the two species. Uncarine D and isorhynchophylline recoveries were over 80%. These results allowed the quantification of both uncarine D and isorhynchophylline in pig plasma after intravenous administration of M. inermis extract. PMID:20437411

  13. Chromatographic techniques coupled with mass spectrometry for the determination of organic acids in the study of autism.

    PubMed

    Kałużna-Czaplińska, Joanna; Zurawicz, Ewa; Jóźwik, Jagoda

    2014-08-01

    Chromatographic methods find application in the diagnostics and prognosis of diseases. They are used in finding new biomarkers, which may result in early medical intervention. Early diagnosis and intervention are especially important in the case of diseases of unknown etiology. One of these is autism. Autism is a neurodevelopmental disorder characterized by severe impairment in reciprocal social interaction and communication and a pattern of repetitive or stereotyped behavior. Organic acids are intermediate metabolites of all major groups of organic cellular components and can play a role in the pathogenesis of autism. This review presents information about abnormal levels of some organic acids observed in the urine of children with autism and determination of acids with the use of chromatographic techniques. 342 literature sources on frequency (2005-2012) of the use of chromatographic methods in the determination of organic compounds in various body fluids were searched.

  14. Implementation of Electrokinetic-ISCO Remediation

    NASA Astrophysics Data System (ADS)

    Wu, M. Z.; Reynolds, D.; Fourie, A.; Prommer, H.; Thomas, D.

    2011-12-01

    Significant challenges remain in the remediation of low-permeability porous media (e.g. clays, silts) contaminated with dissolved and sorbed organic contaminants. Current remediation technologies, such as in-situ chemical oxidation (ISCO), are often ineffective and the treatment region is limited by very slow rates of groundwater flow (advection) or molecular diffusion. At the laboratory-scale several studies (e.g. Reynolds et al. 2008) have highlighted the potential for utilising electrokinetic transport, as induced by the application of an electric field, to deliver a remediation compound (e.g. permanganate, persulfate) within heterogeneous and low-permeability sediments for ISCO (termed EK-ISCO) or other treatments. Process-based numerical modelling of the coupled flow, transport and reaction processes can provide important insights into the prevailing controls and feedback mechanisms and therefore guide the optimisation of EK-ISCO remediation efficacy. In this study, a numerical model was developed that simulates groundwater flow and multi-species reactive transport under both hydraulic and electric gradients (Wu et al. 2010). Coupled into the existing, previously verified reactive transport model PHT3D (Prommer et al. 2003), the model was verified against analytical solutions and data from experimental studies. Using the newly developed model, the sensitivity of electrokinetic, hydraulic and engineering parameters as well as alternative configurations of the EK-ISCO treatment process were investigated. The duration and energy required for remediation was most dependent upon the applied voltage gradient and the natural oxidant demand and all investigated parameters affected the remediation process to some extent. Investigated variants of treatment configurations included several alternative locations for oxidant injection and a series of one-dimensional and two-dimensional electrode configurations.

  15. Micellar Electrokinetic Chromatography of Aminoglycosides.

    PubMed

    Holzgrabe, Ulrike; Schmitt, Stefanie; Wienen, Frank

    2016-01-01

    The components of the aminoglycosides, e.g., gentamicin, sisomicin, netilmicin, kanamycin, amikacin, and tobramycin, and related impurities of these antibiotics can be separated by means of micellar electrokinetic chromatography (MEKC). Derivatization with o-phthaldialdehyde and thioglycolic acid is found to be appropriate for these antibiotics. The background electrolyte was composed of sodium tetraborate (100 mM), sodium deoxycholate (20 mM), and β-cyclodextrin (15 mM) having a pH value of 10.0. This method is valid for evaluation of gentamicin, kanamycin, and tobramycin. It has to be adopted for amikacin, paromomycin, neomycin, and netilmicin. PMID:27645732

  16. Electrokinetic transport and separations in fluidic nanochannels.

    PubMed

    Yuan, Zhen; Garcia, Anthony L; Lopez, Gabriel P; Petsev, Dimiter N

    2007-02-01

    This article presents a summary of theory, experimental studies, and results for the electrokinetic transport in small fluidic nanochannels. The main focus is on the effect of the electric double layer on the EOF, electric current, and electrophoresis of charged analytes. The double layer thickness can be of the same order as the width of the nanochannels, which has an impact on the transport by shaping the fluid velocity profile, local distributions of the electrolytes, and charged analytes. Our theoretical consideration is limited to continuum analysis where the equations of classical hydrodynamics and electrodynamics still apply. We show that small channels may lead to qualitatively new effects like selective ionic transport based on charge number as well as different modes for molecular separation. These new possibilities together with the rapid development of nanofabrication capabilities lead to an extensive experimental effort to utilize nanochannels for a variety of applications, which are also discussed and analyzed in this review. PMID:17304495

  17. Dielectrophoretic concentration of particles under electrokinetic flow

    DOEpatents

    Miles, Robin R.; Bettencourt, Kerry A.; Fuller, Christopher K.

    2004-09-07

    The use of dielectrophoresis to collect particles under the conditions of electrokinetically-driven flow. Dielectrophortic concentration of particles under electrokinetic flow is accomplished by interdigitated electrodes patterned on an inner surface of a microfluid channel, a DC voltage is applied across the ends to the channel, and an AC voltage is applied across the electrodes, and particles swept down the channel electrokinetically are trapped within the field established by the electrodes. The particles can be released when the voltage to the electrodes is released.

  18. MULTISPECTRAL IDENTIFICATION OF POTENTIALLY HAZARDOUS BYPRODUCTS OF OZONATION AND CHLORINATION - PART I: STUDIES OF CHROMATOGRAPHIC AND SPECTROSCOPIC PROPERTIES OF MX

    EPA Science Inventory

    The gas chromatographic (GC) and Fourier transform infrared and mass spectroscopic (FT-IR and MS, respectively) properties of (Z)-2-chloro-3-(dichloromethyl)4-oxobutenoic acid (MX) (a highly mutagenic byproduct of drinking water chlorination) and several related compounds were st...

  19. Evaluation of capillary chromatographic supports for immobilized human purine nucleoside phosphorylase in frontal affinity chromatography studies.

    PubMed

    de Moraes, Marcela Cristina; Temporini, Caterina; Calleri, Enrica; Bruni, Giovanna; Ducati, Rodrigo Gay; Santos, Diógenes Santiago; Cardoso, Carmen Lucia; Cass, Quezia Bezerra; Massolini, Gabriella

    2014-04-18

    The aim of this work was to optimize the preparation of a capillary human purine nucleoside phosphorylase (HsPNP) immobilized enzyme reactor (IMER) for characterization and affinity screening studies of new inhibitors by frontal affinity chromatography coupled to mass spectrometry (FAC-MS). For this purpose two monolithic supports, a Chromolith Speed Rod (0.1mm I.D.×5cm) and a methacrylate-based monolithic epoxy polymeric capillary column (0.25mm I.D.×5cm) with epoxy reactive groups were considered and compared to an IMER previously developed using an open fused silica capillary. Each HsPNP-IMER was characterized in terms of catalytic activity using Inosine as standard substrate. Furthermore, they were also explored for affinity ranking experiments. Kd determination was carried out with the based fused silica HsPNP-IMER and the results are herein discussed.

  20. Synthesis, spectroscopic and chromatographic studies of sunflower oil biodiesel using optimized base catalyzed methanolysis.

    PubMed

    Naureen, Rizwana; Tariq, Muhammad; Yusoff, Ismail; Chowdhury, Ahmed Jalal Khan; Ashraf, Muhammad Aqeel

    2015-05-01

    Methyl esters from vegetable oils have attracted a great deal of interest as substitute for petrodiesel to reduce dependence on imported petroleum and provide an alternate and sustainable source for fuel with more benign environmental properties. In the present study biodiesel was prepared from sunflower seed oil by transesterification by alkali-catalyzed methanolysis. The fuel properties of sunflower oil biodiesel were determined and discussed in the light of ASTM D6751 standards for biodiesel. The sunflower oil biodiesel was chemically characterized with analytical techniques like FT-IR, and NMR ((1)H and (13)C). The chemical composition of sunflower oil biodiesel was determined by GC-MS. Various fatty acid methyl esters (FAMEs) were identified by retention time data and verified by mass fragmentation patterns. The percentage conversion of triglycerides to the corresponding methyl esters determined by (1)H NMR was 87.33% which was quite in good agreement with the practically observed yield of 85.1%.

  1. Synthesis, spectroscopic and chromatographic studies of sunflower oil biodiesel using optimized base catalyzed methanolysis

    PubMed Central

    Naureen, Rizwana; Tariq, Muhammad; Yusoff, Ismail; Chowdhury, Ahmed Jalal Khan; Ashraf, Muhammad Aqeel

    2014-01-01

    Methyl esters from vegetable oils have attracted a great deal of interest as substitute for petrodiesel to reduce dependence on imported petroleum and provide an alternate and sustainable source for fuel with more benign environmental properties. In the present study biodiesel was prepared from sunflower seed oil by transesterification by alkali-catalyzed methanolysis. The fuel properties of sunflower oil biodiesel were determined and discussed in the light of ASTM D6751 standards for biodiesel. The sunflower oil biodiesel was chemically characterized with analytical techniques like FT-IR, and NMR (1H and 13C). The chemical composition of sunflower oil biodiesel was determined by GC–MS. Various fatty acid methyl esters (FAMEs) were identified by retention time data and verified by mass fragmentation patterns. The percentage conversion of triglycerides to the corresponding methyl esters determined by 1H NMR was 87.33% which was quite in good agreement with the practically observed yield of 85.1%. PMID:25972756

  2. Reverse-phase liquid chromatographic determination of clioquinol in cream and ointment preparations: collaborative study.

    PubMed

    Wojtowicz, E J

    1989-01-01

    Seven laboratories participated in a collaborative study to analyze, in duplicate, 2 synthetic formulations and 2 commercial preparations, labeled to contain 3% clioquinol. Clioquinol is determined as its nickel (II) complex by reverse-phase liquid chromatography on a phenyl-bonded column with a mobile phase of acetonitrile-methanol-water, containing ammonium acetate and nickel chloride. Detection is at 273 nm and diphenylamine is added as an internal standard. Mean recoveries were 99.1 and 101.1%, respectively, for the ointment and cream synthetic preparations and 96.7 and 99.7%, respectively, for the commercial ointment and cream. All results are consistent with the variability of other methods at this concentration range. The method has been approved interim official first action.

  3. Electrokinetic Microstrirring to Enhance Immunoassays

    NASA Astrophysics Data System (ADS)

    Feldman, Hope; Sigurdson, Marin; Meinhart, Carl

    2006-11-01

    Electrokinetic microstirring is used to improve the sensitivity of microfluidic heterogeneous immuno-sensors by enhancing the transport in diffusion-limited reactions. The AC electrokinetic force, Electrothermal Flow, is exploited to create a circular stirring fluid motion, thereby providing more binding opportunities between suspended and wall-immobilized molecules. This process can significantly reduce test times, important for both field-portable biosensors and for lab-based assays. A 2-D numerical simulation model is used to predict the effect of electrothermal flow on a heterogeneous immunoassay resulting from an AC potential applied to two parallel electrodes. The binding is increased by a factor of 7 for an applied voltage of 10 Vrms. The effect was investigated experimentally using a high affinity biotin-streptavidin reaction. Microstirred reaction rates were compared with passive reactions. The measurements show on average an order of magnitude increase in binding between immobilized biotin and fluorescently-labeled streptavidin after 5 minutes. Therefore, this technique shows significant promise for reducing incubation time and enhancing the sensitivity of immunoassays.

  4. Electrokinetic instability of isotachophoresis shocks

    NASA Astrophysics Data System (ADS)

    Garcia, Giancarlo; Santiago, Juan; Mani, Ali

    2013-11-01

    Isotachophoresis (ITP) is an electrokinetic focusing technique used in a variety of life science and analytical chemistry applications. In ITP, an electrokinetic shock wave forms at the interface between leading and trailing electrolytes with relatively high and low conductivities. The ITP interface is self-sharpening, as restoring electromigration fluxes counteract molecular diffusion. However, the large electric field gradient at the shock interface also gives rise to free charge and strong electrostatic body forces. At large applied currents, electrostatic forces cause recirculating flows which destabilize the ITP interface. We performed stability analysis and direct simulation of ITP shocks through numerical solutions to the coupled Nernst-Planck and Navier-Stokes equations using a quasi-electroneutral approximation. In both experiments and numerical simulations, we observe two modes of instability: 1) a distorted ITP interface which is steady in time, and 2) an oscillating perturbation which persists. In addition, at the highest simulated electric fields, we observe transition towards more chaotic oscillatory modes. We use our stability analysis and numerical simulations to characterize instability of ITP shocks using two dimensionless parameters.

  5. Microminiature gas chromatographic column

    NASA Technical Reports Server (NTRS)

    Donaldson, R. W., Jr.

    1972-01-01

    Techniques commonly used for fabrication of integrated circuits are utilized to produce long capillary tubes for microminiature chromatographs. Method involves bonding of flat silicon plate to top of spirally grooved silicon chip to close groove and form capillary column.

  6. High-Performance Liquid Chromatographic Determination of Rivastigmine in Human Plasma for Application in Pharmacokinetic Studies

    PubMed Central

    Amini, Hossein; Ahmadiani, Abolhassan

    2010-01-01

    A simple and reproducible HPLC method with spectrophotometric detection was developed for determination of rivastigmine in human plasma. Liquid-liquid extraction of rivastigmine and donepezil (as internal standard) from plasma samples was performed with 1-butanol/n-hexane (2:98 v/v) in alkaline condition followed by back-extraction into diluted acetic acid. Chromatography was carried out using a Silica column (250 mm × 4.6 mm, 5 μm) under isocratic elution with acetonitrile-50 mM aqueous sodium dihydrogen phosphate (17: 83 v/v, pH 3.1. Analyses were run at a flow-rate of 1.3 mL/min at of 50°C. The recovery was 90.8% and 95.7% for rivastigmine and the internal standard donepezil, respectively. The precision of the method was 2.6% to 9.1% over the concentration range of 0.5-16 ng/mL for rivastigmine in plasma with a linearity greater than 0.999. The method was specific and sensitive, with a quantification limit of 0.5 ng/mL and a detection limit of 0.2 ng/mL in plasma. The method was used for a bioequivalence study in healthy subjects. PMID:24363716

  7. The chromatographic performance of flow-through particles: A computational fluid dynamics study.

    PubMed

    Smits, Wim; Nakanishi, Kazuki; Desmet, Gert

    2016-01-15

    The performance of flow-through particles has been studied by computational fluid dynamics. Computational fluid dynamics simulations was used to calculate the flow behaviour around and inside the particles rather than estimate it. The obtained flow field has been used to accurately simulate plate heights generated by flow-through particles and compare them to standard fully porous particles. The effects of particle size, particle porosity and microparticle size on the intra-particle flow and plate heights is investigated. It is shown that the intra-particle flow generates mass transfer enhancement which lowers the total plate height. An empirical model is proposed for the mass transfer enhancement and it is compared to previously proposed models. Kinetic plots are constructed for the flow-through particles. Counter-intuitively, columns packed with flow-through particles have a higher flow resistance which counters the advantages of lower plate heights. Flow-through particles offer no significant gain in kinetic performance over fully porous particles. PMID:26724098

  8. In situ electrokinetic remediation of As-, Cu-, and Pb-contaminated paddy soil using hexagonal electrode configuration: a full scale study.

    PubMed

    Jeon, Eun-Ki; Jung, Ji-Min; Kim, Woo-Seung; Ko, Sung-Hwan; Baek, Kitae

    2015-01-01

    We investigated the in situ applicability of the electrokinetic process with a hexagonal electrode configuration in order to remediate arsenic (As)-, copper (Cu)-, and lead (Pb)-contaminated paddy rice field soil at a field scale (width 17 m, length 12.2 m, and depth 1.6 m). An iron electrode was used in order to prevent the severe acidification of the soil near the anode. We selected ethylenediaminetetraacetic acid (EDTA) as a pursing electrolyte to enhance the extraction of Cu and Pb. The system removed 44.4% of the As, 40.3% of the Cu, and 46.6% of the Pb after 24 weeks of operation. Fractionation analysis showed that the As bound to amorphous ion (Fe) and aluminum (Al) oxyhydroxides was changed into a form of As specifically bound. In the case of Cu and Pb, the fraction bound to Fe-Mn oxyhydroxide primarily decreased. The EDTA formed negatively charged complexes with Cu and Pb, and those complexes were transported toward the anode. The energy consumption was very low compared to that on a small scale because there was less energy consumption due to Joule heating. These results show that the in situ electrokinetic process could be applied in order to remediate paddy rice fields contaminated with multiple metals. PMID:25103944

  9. Testing and evaluation of electrokinetic decontamination of concrete

    SciTech Connect

    DePaoli, D.W.; Harris, M.T.; Ally, M.R.

    1996-10-01

    The goals and objectives of the technical task plan (TTP) are to (1) describe the nature and extent of concrete contamination within the Department of Energy (DOE) complex and emerging and commercial technologies applicable to these problems; (2) to match technologies to the concrete problems and recommend up to four demonstrations; (3) to initiate recommended demonstrations; and (4) to continue investigation and evaluation of the application of electrokinetic decontamination processes to concrete. This document presents findings of experimental and theoretical studies of the electrokinetic decontamination (EK) process and their implications for field demonstrations. This effort is an extension of the work performed under TTP 142005, ``Electroosmotic Concrete Decontamination. The goals of this task were to determine the applicability of EK for treating contaminated concrete and, if warranted, to evaluate EK as a potential technology for demonstration. 62 refs.

  10. AC Electrokinetics of Physiological Fluids for Biomedical Applications.

    PubMed

    Lu, Yi; Liu, Tingting; Lamanda, Ariana C; Sin, Mandy L Y; Gau, Vincent; Liao, Joseph C; Wong, Pak Kin

    2015-12-01

    Alternating current (AC) electrokinetics is a collection of processes for manipulating bulk fluid mass and embedded objects with AC electric fields. The ability of AC electrokinetics to implement the major microfluidic operations, such as pumping, mixing, concentration, and separation, makes it possible to develop integrated systems for clinical diagnostics in nontraditional health care settings. The high conductivity of physiological fluids presents new challenges and opportunities for AC electrokinetics-based diagnostic systems. In this review, AC electrokinetic phenomena in conductive physiological fluids are described followed by a review of the basic microfluidic operations and the recent biomedical applications of AC electrokinetics. The future prospects of AC electrokinetics for clinical diagnostics are presented.

  11. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1994-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  12. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1994-09-13

    A method and apparatus are disclosed for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water. 1 fig.

  13. Initial Water Content and Temperature Effects on Electrokinetic Removal of Aluminium in Drinking Water Sludge

    NASA Astrophysics Data System (ADS)

    Cherifi, M.; Hazourli, S.; Ziati, M.

    2009-11-01

    Electrokinetics is a developping technology that is intended to separate and extract heavy metals, radionuclides, and organic contaminants from saturated or unsaturated soils, sludges and sediments, and groundwater. The goal of electrokinetic remediation is to effect the migration of subsurface contaminants in an imposed electric field. This technique is known as electrokinetic remediation, electroreclamation, electrochemical decontamination, electrorestoration, electromigration or electrochemical soil processing. Electrokinetics involves the installation of electrodes into the subsurface surrounding the contaminated region. After the electrodes are in place, a low electrical potential is applied across the anode(s) (positively charged electrode) and the cathode(s) (negatively charged electrode). As a result of the electrical gradient, different physico-chemical reactions occur and contaminant transport occurs due to various mechanisms within the soil and groundwater. Generally, for the migration to be significant, the contaminants should be in a soluble form. If they are not soluble, they need to be desorbed, dissolved, and/or solubilized into the pore solution before they can be adequately transported from the soil to an electrode wells/reservoirs. Different types of contaminants have been investigated and research has been conducted to optimize the electrokinetic variables. The present study was undertaken to systematically investigate the effect of initial sludge water content, and heating on the electrokinetic remediation of alumium-contaminated sludge. A total of four laboratory experiments were conducted using drinking water sludge. The first two tests studied the effect of variation of initial sludge water content under an ambient temperature, and the last two tests studied the effect of heating on electrokinetic remediation under conditions of both constant saturation and applied voltage.

  14. Study on 3D surfactant assisted electrokinetic remediation of 1,2,4-trichlorobenzene in low permeability soil

    NASA Astrophysics Data System (ADS)

    Qiao, W.; Ye, S.; Wu, J.

    2014-12-01

    Electrickinetic(EK) is a promising remediation technology because of its capability to remediate soils with low permeability. It has been used for heavy metals and organic pollutant(OPs) contaminated soils. As the most OPs are poor solubility and strong sorption capacity, combined EK technology is usually used, for example, EK combined with surfactants. Numerous combined EK tests are done in one-dimension(1D) column, however, it is proved that there is a big gap between 1D tests and field application. The objectives of this study are to investigate the remediation efficiency and EK behavior of 1,2,4-trichlorobenzene(1,2,4-TCB) contaminated clay enhanced by surfactants in a three-dimension reactor with 28cm length×15cm width×16cm height. 1,2,4-TCB was one of the main contaminants at a field site in Nanjing, China, where the polluted soils are clay. Soil filled in EK cell was divided into six layers in depth, and each layer was divided into six parts in length and three parts in width. There were 108 specimens in total which realized 3D monitoring the effects of EK. Triton X-100(Exp1) and Tween80(Exp2) dissolved in NaCO3/NaHCO3 buffer respectively, were used as the anode purging solution. The distributions of soil pH and water content showed that the buffer was sufficient to neutralize H+ produced at anode and the direction of electroosmotic flow(EOF) remained constant. Exp2 generated a higher EOF than Exp1, but remediation efficiencies were not satisfactory so far. The concentration of 1,2,4-TCB in soil reached a peak and nadir in the normalized distances of 0.75 and 0.9 from cathode after 5 days, respectively. The 1,2,4-TCB concentration in the peak was almost twice as much as the initial concentration. It suggested that 1,2,4-TCB was desorbed from soil by surfactants and was transported from anode to cathode by EOF, which proved the capability of EK with surfactants to move 1,2,4-TCB in clay. The concentration of 1,2,4-TCB in the normalized distances of 0

  15. Enhancing the Efficiency of Electrokinetic Remediation through Technology Integration

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Komai, T.

    2009-12-01

    Remediation or cleanup of soils and groundwater polluted by heavy metals remains a challenge in the field of geo-environmental engineering. Many sites, like ore dressing plants, electroplating plants and battery factories may be polluted by heavy metals. In addition, some natural factors like metal deposits or abundant metal mines, hot springs and volcanic eruptions may also cause heavy metal pollutions. Unlike organic pollutants, heavy metals do not decay naturally, and active approaches to remediation are generally necessary. Although electrokinetic method is considered to be the only technique that is highly-perspective for in situ remediation of heavy metals, and numerous bench-scale studies as well as a few pilot scale experiments illustrated its applicability, this technique has not yet been widely used in practice due to the low efficiencies and/or unacceptable long remediation periods. To enhance the total efficiency of electrokinetic remediation, a systematic approach by integrating different technologies is proposed. This systematic approach includes 1) on-site quick mapping for screening out localized pollution areas, characterizing chemical composition of polluted soils, and for examining the progress of in situ remediation; 2) electrical resistivity tomography(ERT) or electrical resistivity imaging(ERI) for predicting geological structure and hydrogeological boundaries conditions of a polluted site, and for optimizing parameters like voltage and current density for an effective remediation; 3) the use of solar energy to increase flexibility in and applicability of electrokinetic technique; 4) combination with large scale modeling tests for a pertinent evaluation of the feasibility related to electrokinetic remediation for a given soil type taken from a specific polluted site; 5) combination with risk-assessment method to determine feasible cleanup levels; and 6) recovery of heavy metals deposited on electrode plates for possible use as resources

  16. AC Electrokinetic Cell Separation on a Microfluidic Device

    NASA Astrophysics Data System (ADS)

    Gagnon, Zachary; Chang, Hsueh-Chia

    2009-03-01

    Rapid cell separation and collection is demonstrated through the integration of electrokinetic pumps, dielectrophoretic (DEP) traps and field driven valves into a well designed microfluidic channel loop. We present the ground-up design and analysis of this fully functional microfluidic device for the rapid separation and collection of live and dead yeast cells and malaria red blood cells (RBCs) at low concentrations. DEP cell sorting and concentration schemes are based on the exploitation of cell specific DEP crossover frequencies (cof's). A rigorous DEP study of yeast and RBCs is presented and used to determine optimal conditions for cell separation. By utilizing a glutaraldehyde crosslinking cell fixation reaction that is sensitive to cell membrane protein concentration, we demonstrate the ability to further amplify these differences between healthy and unhealthy cells as well as stabilize their DEP cof's. Pumping is achieved with a new type of electrokinetic flow, AC electrothermal electro-osmosis (ETEO) and is shown to scale inversely with the field induced debye length and drive fluid velocities in excess of 6 mm/sec. The well characterized electrokinetic phenomena are integrated into a microchannel loop with a specifically designed electrode field penetration length for low concentration cell separation and concentration.

  17. [Optimization of electrode configuration in soil electrokinetic remediation].

    PubMed

    Liu, Fang; Fu, Rong-Bing; Xu, Zhen

    2015-02-01

    Electric field distributions of several different electrode configurations in non-uniform electric field were simulated using MATLAB software, and the electrokinetic remediation device was constructed according to the best electrode configuration. The changes of soil pH and heavy metal residues in different parts of the device during the electrokinetic remediation were also studied. The results showed that, in terms of the effectiveness of the electric field strength, the square (1-D-1) and hexagonal (2-D-3) were the optimal electrode configurations for one-dimensional and two-dimensional respectively and the changes of soil pH, the removal of heavy metals and the distribution of electric field were closely related to one another. An acidic migration band, which could prevent premature precipitation of heavy metals to a certain extent and promote electrokinetic removal of heavy metals, was formed gradually along with the remediation in the whole hexagon device when the cathodic pH was controlled during the remediation of the four cationic metallic ions, Cd2+, Ni2+, Pb2+ and Cu2+. After 480-hour remediation, the total removals of Cd, Ni, Pb and Cu were 86.6%, 86.2%, 67.7% and 73.0%, respectively. Remediation duration and replacement frequency of the electrodes could be adjusted according to the repair target. PMID:26031098

  18. Electrokinetic properties of polymer colloids

    NASA Technical Reports Server (NTRS)

    Micale, F. J.; Fuenmayor, D. Y.

    1986-01-01

    The surface of polymer colloids, especially polystyrene latexes, were modified for the purpose of controlling the electrokinetic properties of the resulting colloids. Achievement required a knowledge of electrical double layer charging mechanism, as a function of the electrolyte conditions, at the polymer/water interface. The experimental approach is to control the recipe formulation in the emulsion polymerization process so as to systematically vary the strong acid group concentration on the surface of the polymer particles. The electrophoretic mobility of these model particles will then be measured as a function of surface group concentration and as a function of electrolyte concentration and type. An effort was also made to evaluate the electrophoretic mobility of polystyrene latexes made in space and to compare the results with latexes made on the ground.

  19. Feasibility study of a drug immunoassay based on micellar electrokinetic capillary chromatography with laser induced fluorescence detection: determination of theophylline in serum.

    PubMed

    Steinmann, L; Caslavska, J; Thormann, W

    1995-10-01

    This paper presents principle and first results of a novel competitive binding immunoassay for monitoring of theophylline in human serum. The assay is based upon short time incubation of a mixture of antiserum, containing the antibody raised against theophylline, fluorescein labelled theophylline (tracer) and serum prior to injection of a few nanoliter of this mixture onto a fused-silica capillary for subsequent separation and analysis of free tracer and the antibody-tracer-complex by micellar electrokinetic capillary chromatography with laser induced fluorescence detection. Quantitation based upon multi-level calibration using the height of the peak produced by the free tracer is shown to provide theophylline serum levels which are in agreement with those obtained by a commercial fluorescence polarization immunoassay and with those determined by micellar elektrokinetic capillary chromatography with direct serum injection and on-column UV absorption detection.

  20. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, F.T.

    Intermetallic compounds with the CaCu/sub 5/ type of crystal structure, particularly LaNiCo/sub 4/ and CaNi/sub 5/, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen cn produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  1. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  2. Impact of carbonate on the efficiency of heavy metal removal from kaolinite soil by the electrokinetic soil remediation method.

    PubMed

    Ouhadi, V R; Yong, R N; Shariatmadari, N; Saeidijam, S; Goodarzi, A R; Safari-Zanjani, M

    2010-01-15

    While the feasibility of using electrokinetics to decontaminate soils has been studied by several authors, the effects of soil composition on the efficiency of this method of decontamination has yet to be fully studied. This study focuses its attention on the effect of "calcite or carbonate" (CaCO(3)) on removal efficiency in electrokinetic soil remediation. Bench scale experiments were conducted on two soils: kaolinite and natural-soil of a landfill in Hamedan, Iran. Prescribed quantities of carbonates were mixed with these soils which were subsequently contaminated with zinc nitrate. After that, electrokinetic experiments were conducted to determine the efficiency of electrokinetic remediation. The results showed that an increase in the quantity of carbonate caused a noticeable increase on the contaminant retention of soil and on the resistance of soil to the contaminant removal by electrokinetic method. Because the presence of carbonates in the soil increases its buffering capacity, acidification is reduced, resulting in a decrease in the rate of heavy metal removed from the contaminant soil. This conclusion was validated by the evaluation of efficiency of electrokinetic method on a soil sample from the liner of a waste disposal site, with 28% carbonates. PMID:19733966

  3. The optimisation of electrokinetic remediation for heavy metals and radioactivity contamination on Holyrood-Lunas soil (acrisol species) in Sri Gading Industrial Area, Batu Pahat, Johor, Malaysia.

    PubMed

    Mohamed Johar, S; Embong, Z

    2015-11-01

    The optimisation of electrokinetic remediation of an alluvial soil, locally named as Holyrood-Lunas from Sri Gading Industrial Area, Batu Pahat, Johor, Malaysia, had been conducted in this research. This particular soil was chosen due to its relatively high level of background radiation in a range between 139.2 and 539.4 nGy h(-1). As the background radiation is correlated to the amount of parent nuclides, (238)U and (232)Th, hence, a remediation technique, such as electrokinetic, is very useful in reducing these particular concentrations of heavy metal and radionuclides in soils. Several series of electrokinetics experiments were performed in laboratory scale in order to study the influence of certain electrokinetic parameters in soil. The concentration before (pre-electrokinetic) and after the experiment (post-electrokinetic) was determined via X-ray fluorescence (XRF) analysis technique. The best electrokinetic parameter that contributed to the highest achievable concentration removal of heavy metals and radionuclides on each experimental series was incorporated into a final electrokinetic experiment. Here, High Pure Germanium (HPGe) was used for radioactivity elemental analysis. The XRF results suggested that the most optimised electrokinetic parameters for Cr, Ni, Zn, As, Pb, Th and U were 3.0 h, 90 volts, 22.0 cm, plate-shaped electrode by 8 × 8 cm and in 1-D configuration order whereas the selected optimised electrokinetic parameters gave very low reduction of (238)U and (232)Th at 0.23 ± 2.64 and 2.74 ± 23.78 ppm, respectively. PMID:25920778

  4. Application of a sensitive liquid chromatographic/tandem mass spectrometric method to pharmacokinetic study of nalmefene in humans.

    PubMed

    Li, Ping; Chen, Xiaoyan; Dai, Xiaojian; Wen, Aidong; Zhang, Yifan; Zhong, Dafang

    2007-06-01

    A sensitive, specific and rapid liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed and validated for quantification of nalmefene in human plasma. An aliquot of 200 microL plasma sample was simply precipitated by 400 microL methanol. Separation of nalmefene and the internal standard hydromorphone from the interferences was achieved on a C(18) column followed by MS/MS detection. The analytes were monitored in the positive ionization mode with a TurboIonspray source. The method had a total chromatographic run time of 4.5 min and linear calibration curves over the concentration range of 10-5000 pg/mL. The lower limit of quantification (LLOQ) was 10 pg/mL. The intra- and inter-day precision was less than 10.1% determined from QC samples at concentrations of 30, 300 and 4500 pg/mL, and the accuracy was within +/-3.4%. As the method was more sensitive (10 times higher) than those reported previously, we investigated the pharmacokinetics of nalmefene in healthy volunteers after a single intravenous injection of low dose (30 microg) of nalmefene hydrochloride for the first time.

  5. Micellar electrokinetic chromatography as a fast screening method for the determination of 1,4-dihydropyridine calcium antagonists.

    PubMed

    Martínez, V; López, J A; Alonso, R M; Jiménez, R M

    1999-03-19

    A micellar electrokinetic chromatographic method (MEKC) was optimized for the separation of six calcium antagonists. The effects of the buffer (concentration and pH), concentration of sodium dodecyl sulphate (SDS), the organic modifier, the injection time, and the voltage applied were studied. A final appropriate electrolyte of 50 mM borate buffer, pH 8.2, containing 20 mM SDS and 15% (v/v) acetonitrile was found to provide the optimum separation with respect to resolution and migration time. The samples were introduced hydrostatically for 4 s at 50 mbar injection pressure and the applied voltage was +25 kV. The screening of the six compounds was achieved in less than 15 min: nifedipine (migration time, tm = 6.9 min), nimodipine (tm = 10.1 min), felodipine (tm = 12.2 min), nicardipine hydrochloride (tm = 12.7 min), lacidipine (tm = 13.5 min) and amlodipine besylate (tm = 14.1 min, tm = 8 min). The method developed showed to be linear at least up to 70 micrograms/ml with a detection limit of about 5 micrograms/ml for each compound. The within-day and inter-day area reproducibility (R.S.D.) were, respectively, lower than 4.8 and 8.6% for six replicate samples.

  6. Sample stacking for the analysis of eight penicillin antibiotics by micellar electrokinetic capillary chromatography.

    PubMed

    Puig, Patricia; Borrull, Francesc; Calull, Marta; Aguilar, Carme

    2005-02-01

    We studied the use of micellar electrokinetic capillary chromatography for separating eight penicillins. The method consists of (i) an electrophoretic separation based on micellar electrokinetic capillary chromatography, which uses sodium dodecyl sulfate (SDS) as surfactant; (ii) a sample stacking technique called reverse electrode polarity stacking mode (REPSM); and (iii) direct UV detection. The background electrolyte that gave complete separation contained 20 mM sodium borate buffer and 60 mM SDS. The sensitivity of the method was improved by an enrichment step that used on-column stacking. The limits of detection were at the microg.L(-1) level for the penicillins and did not detract from the peak resolution.

  7. Elemental composition study of heavy metal (Ni, Cu, Zn) in riverbank soil by electrokinetic-assisted phytoremediation using XRF and SEM/EDX

    NASA Astrophysics Data System (ADS)

    Jamari, Suhailly; Embong, Zaidi; Bakar, Ismail

    2014-02-01

    Electrokinetic (EK)-assisted phytoremediation is one of the methods that have a big potential in enhancing the ability of plant uptake in soils remediation process. This research was conducted to investigate the difference in elemental composition concentration of riverbank soil and the change of pH between pre- and post-phytoremediation under the following condition: 1) control or as-receive sample; 2) Dieffenbachia spp plant with EK system (a pair of EK electrodes connected to a direct current (DC) power supply). After the electrodes were connected to a magnitude of 6V/cm-1 electric field for 4 hours/day, the soil and plant samples were analyzed using and X-ray Fluorescence Spectrometer (XRF) and Scanning Electron Microscope / Energy Dispersive X-ray Spectroscopy (SEM/EDX). The SEM/EDX analysis showed that concentration of elemental composition (Ni, Cu and Zn) in post-phytoremediation plant powder samples had increase while elemental concentrations in the post-phytoremediation soil samples were decreased. XRF analysis presented a variation in soil elemental composition concentration from anode to cathode where the concentration near anode region increased while decreased near the cathode region. A significant changes in soil pH were obtained where the soil pH increase in cathode region while decrease in anode region. The results reveal that the assistance of EK in phytoremediation process has increase the efficiency of plant uptake.

  8. Elemental composition study of heavy metal (Ni, Cu, Zn) in riverbank soil by electrokinetic-assisted phytoremediation using XRF and SEM/EDX

    SciTech Connect

    Jamari, Suhailly; Embong, Zaidi; Bakar, Ismail

    2014-02-12

    Electrokinetic (EK)-assisted phytoremediation is one of the methods that have a big potential in enhancing the ability of plant uptake in soils remediation process. This research was conducted to investigate the difference in elemental composition concentration of riverbank soil and the change of pH between pre- and post-phytoremediation under the following condition: 1) control or as-receive sample; 2) Dieffenbachia spp plant with EK system (a pair of EK electrodes connected to a direct current (DC) power supply). After the electrodes were connected to a magnitude of 6V/cm{sup −1} electric field for 4 hours/day, the soil and plant samples were analyzed using and X-ray Fluorescence Spectrometer (XRF) and Scanning Electron Microscope / Energy Dispersive X-ray Spectroscopy (SEM/EDX). The SEM/EDX analysis showed that concentration of elemental composition (Ni, Cu and Zn) in post-phytoremediation plant powder samples had increase while elemental concentrations in the post-phytoremediation soil samples were decreased. XRF analysis presented a variation in soil elemental composition concentration from anode to cathode where the concentration near anode region increased while decreased near the cathode region. A significant changes in soil pH were obtained where the soil pH increase in cathode region while decrease in anode region. The results reveal that the assistance of EK in phytoremediation process has increase the efficiency of plant uptake.

  9. Packed multi-channels for parallel chromatographic separations in microchips.

    PubMed

    Nagy, Andrea; Gaspar, Attila

    2013-08-23

    Here we report on a simple method to fabricate microfluidic chip incorporating multi-channel systems packed by conventional chromatographic particles without the use of frits. The retaining effectivities of different bottlenecks created in the channels were studied. For the parallel multi-channel chromatographic separations several channel patterns were designed. The obtained multipackings were applied for parallel separations of dyes. The implementation of several chromatographic separation units in microscopic size makes possible faster and high throughput separations.

  10. Transient behavior of heavy metals in soils during electrokinetic remediation.

    PubMed

    Al-Hamdan, Ashraf Z; Reddy, Krishna R

    2008-03-01

    This paper presents a systematic bench-scale laboratory study performed to assess the transient behavior of chromium, nickel, and cadmium in different soils during electrokinetic remediation. A series of laboratory electrokinetic experiments was conducted using two different clayey soils, kaolin and glacial till. For each type of soil, four electrokinetic experiments with 1, 2, 4, and 10 d of treatment time were performed. In all tests, the contaminants were Cr(VI), Ni(II), and Cd(II) combined in the soil. A geochemical assessment was performed using the geochemical model MINEQL(+) to determine the partitioning of the heavy metals in soils as precipitated, adsorbed, and aqueous forms. Results showed that in kaolin, the extent of Ni(II) and Cd(II) migration towards the cathode increased as the treatment time increased. Unlike kaolin, in glacial till treatment time had no effect on nickel and cadmium migration because of its high buffering capacity. In both kaolin and glacial till, the extent of Cr(VI) migration towards the anode increased as the treatment time increased. However, Cr(VI) migration was higher in glacial till as compared to kaolin because of the high pH conditions that existed in glacial till. In all tests, some Cr(VI) was reduced to Cr(III), and the Cr(VI) reduction rate to Cr(III) as well as the Cr(III) migration were significantly affected by the treatment time. Overall, this study showed that the electroosmotic flow as well as the direction and extent of contaminant migration and removal depend on the polarity of the contaminant, the type of soil, and the treatment duration. PMID:18155269

  11. Electrokinetic instability near charge-selective hydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Shelistov, V. S.; Demekhin, E. A.; Ganchenko, G. S.

    2014-07-01

    The influence of the texture of a hydrophobic surface on the electro-osmotic slip of the second kind and the electrokinetic instability near charge selective surfaces (permselective membranes, electrodes, or systems of microchannels and nanochannels) is investigated theoretically using a simple model based on the Rubinstein-Zaltzman approach. A simple formula is derived to evaluate the decrease in the instability threshold due to hydrophobicity. The study is complemented by numerical investigations both of linear and nonlinear instabilities near a hydrophobic membrane surface. Theory predicts a significant enhancement of the ion flux to the surface and shows a good qualitative agreement with the available experimental data.

  12. Solute-solvent interactions in micellar electrokinetic chromatography. Selectivity of lithium dodecyl sulfate-lithium perfluorooctanesulfonate mixed-micellar buffers.

    PubMed

    Fuguet, E; Ràfols, C; Bosch, E; Rosés, M; Abraham, M H

    2001-01-12

    The solvation parameter model has been applied to the characterization of micellar electrokinetic chromatographic (MEKC) systems with mixtures of lithium dodecyl sulfate and lithium perfluorooctanesulfonate as surfactant. The variation in MEKC surfactant composition results in changes in the coefficients of the correlation equation, which in turns leads to information on solute-solvent and solute-micelle interactions. Lithium perfluorooctanesulfonate is more dipolar and hydrogen bond acidic but less polarizable and hydrogen bond basic than lithium dodecyl sulfate. Therefore mixtures of lithium dodecyl sulfate and lithium perfluorooctanesulfonate cover a very wide range of polarity and hydrogen bond properties, which in turn results in important selectivity changes for analytes with different solute properties.

  13. Electrokinetic flushing with surrounding electrode arrangements for the remediation of soils that are polluted with 2,4-D: A case study in a pilot plant.

    PubMed

    Risco, C; Rodrigo, S; López-Vizcaíno, R; Sáez, C; Cañizares, P; Navarro, V; Rodrigo, M A

    2016-03-01

    This work aimed to evaluate electrokinetic soil flushing (EKSF) technologies for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from spiked soils using an electrode configuration consisting of one cathode surrounded by six anodes (1c6a) and one anode surrounded by 6 cathodes (1a6c). Experiments were conducted for over one month in a bench-scale set-up (175 dm(3) of capacity) that was completely automated and operated at a constant electric field (1.0V cm(-1)). The electrical current, temperature, pH, moisture and pollutant concentration in electrolyte wells were monitored daily, and at the end of the experiments, an in-depth sectioned analysis of the complete soil section (post-mortem analysis) was conducted. Despite the geometric similarity, the two strategies led to very different results mainly in terms of water and herbicide mobilization, whereas pH and conductivity do not depend strongly on the electrode configuration. The volume of water extracted from cathodes with 1a6c is seven times higher than that of the 1c6a strategy. Herbicide was transported to the anode wells by electromigration and then dragged toward the cathode wells by electro-osmotic fluxes, with the first process being much more important. The configuration 1c6a was the most efficient and attained a transfer of 70% of the herbicide contained in the soil to flushing water in 35 days. These results outperform those obtained by the configuration 1a6c, for which less than 8% of the herbicide was transferred to flushing fluids in a much longer time (58 days). PMID:26747990

  14. Modeling the electrokinetic decontamination of concrete

    SciTech Connect

    Harris, M.T.; DePaoli, D.W.; Ally, M.R.

    1997-01-01

    The decontamination of concrete is a major concern in many Department of (DOE) facilities. Numerous techniques (abrasive methods, manual methods, ultrasonics, concrete surface layer removal, chemical extraction methods, etc.) have been used to remove radioactive contamination from the surface of concrete. Recently, processes that are based on electrokinetic phenomena have been developed to decontaminate concrete. Electrokinetic decontamination has been shown to remove from 70 to over 90% of the surface radioactivity. To evaluate and improve the electrokinetic processes, a model has been developed to simulate the transport of ionic radionuclei constituents through the pores of concrete and into the anolyte and catholyte. The model takes into account the adsorption and desorption kinetics of the radionuclei from the pore walls, and ion transport by electro-osmosis, electromigration, and diffusion. A numerical technique, orthogonal collocation, is used to simultaneously solve the governing convective diffusion equations for a porous concrete slab and the current density equation. This paper presents the theoretical framework of the model and the results from the computation of the dynamics of ion transport during electrokinetic treatment of concrete. The simulation results are in good agreement with experimental data.

  15. Opto-electrokinetic manipulation technique for highperformance

    SciTech Connect

    Kwon, Jae-Sung; Ravindranath, Sandeep; Kumar, Aloke; Irudayaraj, Joseph; Wereley, Steven T.

    2012-01-01

    This communication first demonstrates bio-compatibility of a recently developed opto-electrokinetic manipulation technique, using microorganisms. Aggregation, patterning, translation, trapping and size-based separation of microorganisms performed with the technique firmly establishes its usefulness for development of a high-performance on-chip bioassay system.

  16. Spectral induced polarization for monitoring electrokinetic remediation processes

    NASA Astrophysics Data System (ADS)

    Masi, Matteo; Losito, Gabriella

    2015-12-01

    Electrokinetic remediation is an emerging technology for extracting heavy metals from contaminated soils and sediments. This method uses a direct or alternating electric field to induce the transport of contaminants toward the electrodes. The electric field also produces pH variations, sorption/desorption and precipitation/dissolution of species in the porous medium during remediation. Since heavy metal mobility is pH-dependent, the accurate control of pH inside the material is required in order to enhance the removal efficiency. The common approach for monitoring the remediation process both in laboratory and in the field is the chemical analysis of samples collected from discrete locations. The purpose of this study is the evaluation of Spectral Induced Polarization as an alternative method for monitoring geochemical changes in the contaminated mass during remediation. The advantage of this technique applied to field-scale is to offer higher resolution mapping of the remediation site and lower cost compared to the conventional sampling procedure. We carried out laboratory-scale electrokinetic remediation experiments on fine-grained marine sediments contaminated by heavy metal and we made Spectral Induced Polarization measurements before and after each treatment. Measurements were done in the frequency range 10- 3-103 Hz. By the deconvolution of the spectra using the Debye Decomposition method we obtained the mean relaxation time and total chargeability. The main finding of this work is that a linear relationship exists between the local total chargeability and pH, with good agreement. The observed behaviour of chargeability is interpreted as a direct consequence of the alteration of the zeta potential of the sediment particles due to pH changes. Such relationship has a significant value for the interpretation of induced polarization data, allowing the use of this technique for monitoring electrokinetic remediation at field-scale.

  17. Liquid chromatographic method for determination of patulin in clear and cloudy apple juices and apple puree: collaborative study.

    PubMed

    MacDonald, S; Long, M; Gilbert, J; Felgueiras, I

    2000-01-01

    A collaborative trial was conducted to validate the effectiveness of a liquid chromatographic (LC) procedure for determination of patulin in both clear and cloudy apple juices and apple puree. The test portion of clear apple juice was directly extracted with ethyl acetate; cloudy apple juice and apple puree were treated with pectinase enzyme before extraction. After back-extraction into sodium carbonate to remove interfering acidic compounds, the extract was dried and concentrated, and patulin was determined by LC with UV detection. Clear and cloudy apple juices, apple puree test samples naturally contaminated with patulin, and blank test samples for spiking with patulin were sent to 14 collaborators in 12 different European countries. Test portions of each of the 3 test sample types were spiked with patulin at 75 ng/g. Recoveries of patulin ranged from 80 to 92%. Based on the results for spiked test samples (blind pairs) and naturally contaminated test samples (blind pairs at 3 levels), the relative standard deviations for repeatability (RSDr) and reproducibility (RSDR) ranged from 8 to 35% and 11 to 36%, respectively. Although HORRAT values of <1.4 were obtained for all 3 matrixes at patulin levels ranging from 26 to 121 ng/g, better performance values (RSDr values 6-10% and RSDR values 11-25%) were obtained for clear and cloudy apple juice spiked above 50 ng/g, which is either the statutory limit or the advisory level for patulin contamination in apple juices in many countries.

  18. Chromatographic studies of purity and segregation behaviour of natural impurities present in coal tar acenaphthene and pyrene

    NASA Astrophysics Data System (ADS)

    Marciniak, B.

    2002-05-01

    Twenty one (two unidentified) and 14 impurities were detected and identified in the bottom parts of the zone refined ingots of commercially available ex-coal tar acenaphthene and pyrene, respectively, with the help of Hewlett-Packard gas chromatographs type 6890 GC System and 5890 series II equipped with fused silica capillary columns and the FID and MS detectors. The result of quantitative determination have shown that naphthalene, 2-methylnaphthalene and 9H-fluorene, and 7-methylanthracene, 1-phenylnaphthalene, fluoranthene and unknown compound with the molecular weight of 208 may be treated as the major impurities of the above hydrocarbons, respectively. These results have also shown that with the exception of methyldibenzofuran present as impurity in acenaphthene, the segregation coefficients of all the remaining detected impurities are lower than unity. Moreover, it was found that the final distribution of the major impurities after 100 passes of the melting zone may be described with high accuracy by a third-order equation. The purification procedure worked out on the basis of the determined impurity segregation behaviour enabled the preparation of the hydrocarbons with purity ⩾99.999 mass% from which high quality crystals were grown.

  19. Determination of rizatriptan in human plasma by liquid chromatographic-eletrospray tandem mass spectrometry: application to a pharmacokinetic study.

    PubMed

    Guo, Ji-fen; Zhang, Ai-jun; Zhao, Ling; Sun, Xiao-hong; Zhao, Yi-min; Gao, Hong-zhi; Liu, Ze-yuan; Qiao, Shan-yi

    2006-01-01

    A sensitive liquid chromatographic-tandem mass spectrometry(LC-MS/MS) method was developed for the determination of rizatriptan in human plasma. The analytes were extracted from plasma samples by liquid-liquid extraction, separated on a Zorbax XDB C8 column (150 x 4.6 mm i.d.) and detected by tandem mass spectrometry with an electrospray ionization interface. Zomitriptan was used as the internal standard. The method had a lower limit of quantitation of 50 pg/mL for rizatriptan, which showed more sensitivity and speed of analysis compared with reported methods. The within- and between-day precision was measured to be below 11.71% and accuracy between -5.87 and 0.86% for all quality control samples. This quantitation method was successfully applied to the evaluation of the pharmacokinetic profiles of rizatriptan after single oral administration of 5, 10 and 15 mg rizatriptan tablets to 10 healthy volunteers (five males and five females). PMID:15954161

  20. The transport behavior of As, Cu, Pb, and Zn during electrokinetic remediation of a contaminated soil using electrolyte conditioning.

    PubMed

    Yang, Jung-Seok; Kwon, Man Jae; Choi, Jaeyoung; Baek, Kitae; O'Loughlin, Edward J

    2014-12-01

    Electrokinetic remediation (also known as electrokinetics) is a promising technology for removing metals from fine-grained soils. However, few studies have been conducted regarding the transport behavior of multi-metals during electrokinetics. We investigated the transport of As, Cu, Pb, and Zn from soils during electrokinetics, the metal fractionation before and after electrokinetics, the relationships between metal transport and fractionation, and the effects of electrolyte conditioning. The main transport mechanisms of the metals were electroosmosis and electromigration during the first two weeks and electromigration during the following weeks. The direction of electroosmotic flow was from the anode to the cathode, and the metals in the dissolved and reducible-oxides fractions were transported to the anode or cathode by electromigration according to the chemical speciation of the metal ions in the pore water. Moreover, a portion of the metals that were initially in the residual fraction transitioned to the reducible and soluble fractions during electrokinetic treatment. However, this alteration was slow and resulted in decreasing metal removal rates as the electrokinetic treatment progressed. In addition, the use of NaOH, H3PO4, and Na2SO4 as electrolytes resulted in conditions that favored the precipitation of metal hydroxides, phosphates, and sulfates in the soil. These results demonstrated that metal removal was affected by the initial metal fractionation, metal speciation in the pore solution, and the physical-chemical parameters of the electrolytes, such as pH and electrolyte composition. Therefore, the treatment time, use of chemicals, and energy consumption could be reduced by optimizing pretreatment and by choosing appropriate electrolytes for the target metals. PMID:24972074

  1. Chromatographic methods of fractionation.

    PubMed

    Friesen, A D

    1987-01-01

    Chromatography's functional versatility, separation efficiency, gentle non-denaturing separating process and ease of automation and scale-up make it attractive for industrial scale protein purification. The Winnipeg Rh Institute's new Plasma Fractionation facility is an example of the use of chromatography for the large scale purification of plasma protein fractions. The fractionation facility has a capacity to process 800 litres of plasma per batch into blood clotting factor VIII and IX, albumin and intravenous immune serum globulin (i.v. ISG). Albumin and i.v. ISG are purified using ion exchange columns of DEAE-Sepharose (230 litre size), DEAE-Biogel (150 litre size) and CM-Sepharose (150 litre size). The chromatographic process is automated using a Modicon 584 Programmable Logic Controller to regulate valves, pumps and sensors which control plasma flow during fractionation. The stainless steel tanks and piping are automatically cleaned-in-place. The high degree of automation and cleaning provides efficient operation and sanitary processing. Chromatographic methods (DEAE-Sepharose and metal chelation) are also being used at the pilot scale to purify the human blood products superoxide dismutase and hemoglobin from outdated red blood cells. Characterization of the protein fractions produced by chromatography has shown them to be of equal or higher quality than fractions produced by other techniques.

  2. Liquid chromatographic determination of the glycoalkaloids alpha-solanine and alpha-chaconine in potato tubers: NMKL Interlaboratory Study. Nordic Committee on Food Analysis.

    PubMed

    Hellenäs, K E; Branzell, C

    1997-01-01

    Twelve laboratories participated in a collaborative study to evaluate precision parameters of a liquid chromatographic method for analysis of the glycoalkaloids alpha-solanine and alpha-chaconine in potato tubers. Samples consisted of frozen potato tuber homogenates distributed as 3 blind duplicates and 3 split-level pairs. The analytical method included aqueous extraction, workup on disposable solid-phase extraction cartridges, and reversed-phase chromatography with photometric detection at 202 nm. Results for alpha-solanine and alpha-chaconine were received from 10 and 9 laboratories, respectively. Relative standard deviations for reproducibility for alpha-solanine and alpha-chaconine were similar, ranging from 8 to 13% in the applied concentration range of 12 to 260 mg/kg fresh weight.

  3. Characteristic chromatographic fingerprint study of short-chain fatty acids in human milk, infant formula, pure milk and fermented milk by gas chromatography-mass spectrometry.

    PubMed

    Jiang, Zhenzuo; Liu, Yanan; Zhu, Yan; Yang, Jing; Sun, Lili; Chai, Xin; Wang, Yuefei

    2016-09-01

    Human milk, infant formula, pure milk and fermented milk as food products or dietary supplements provide a range of nutrients required to both infants and adults. Recently, a growing body of evidence has revealed the beneficial roles of short-chain fatty acids (SCFAs), a subset of fatty acids produced from the fermentation of dietary fibers by gut microbiota. The objective of this study was to establish a chromatographic fingerprint technique to investigate SCFAs in human milk and dairy products by gas chromatography coupled with mass spectrometry. The multivariate method for principal component analysis assessed differences between milk types. Human milk, infant formula, pure milk and fermented milk were grouped independently, mainly because of differences in formic acid, acetic acid, propionic acid and hexanoic acid levels. This method will be important for the assessment of SCFAs in human milk and various dairy products.

  4. Electrokinetic phenomena and dielectrophoresis in charged colloidal suspensions

    NASA Astrophysics Data System (ADS)

    Huang, J. P.; Karttunen, Mikko; Yu, K. W.; Dong, L.

    2003-03-01

    AC electrokinetic phenomena, i.e., electrorotation, dielectrophoresis and traveling wave dielectrophoresis, have gained an increasing amount of attention. This is due to their wide range of applications from cancer research to identifying and separating parasites, cell populations and viruses, and even to design of nanomotors. Despite the number of applications, there is need for a theory that treats the different aspects of electrokinetic phenomena on an equal footing starting from the general underlying physical principles. Here, we present a theoretical study of dielectrophoretic (DEP) crossover spectrum of two polarizable particles under the action of a nonuniform AC electric field. For two approaching particles, the mutual polarization interaction yields a change in their respective dipole moments, and hence, in the DEP crossover spectrum. We use the multiple image method to study the induced polarization effects and using spectral representation theory, an analytic expression for the DEP force is derived. Our results shows that the mutual polarization effects can change the crossover frequency at which the DEP force changes sign. The results are in agreement with recent experimental observations. Importantly, this approach goes beyond the standard theory and helps to clarify the important question of the underlying polarization mechanisms. The extension to dense systems and relation to electrorotation is discussed.

  5. Multi-vortical flow inducing electrokinetic instability in ion concentration polarization layer.

    PubMed

    Kim, Sung Jae; Ko, Sung Hee; Kwak, Rhokyun; Posner, Jonathan D; Kang, Kwan Hyoung; Han, Jongyoon

    2012-12-01

    In this work, we investigated multiple vortical flows inside the ion concentration polarization (ICP) layer that forms due to a coupling of applied electric fields and the semipermeable nanoporous junction between microchannels. While only a primary vortex near perm-selective membrane is traditionally known to lead to electrokinetic instability, multiple vortexes induced by the primary vortex were found to play a major role in the electrokinetic instability. The existence of multiple vortexes was directly confirmed by experiments using particle tracers and interdigitated electrodes were used to measure the local concentration profile inside the ICP layer. At larger applied electric fields, we observed aperiodic fluid motion due to electrokinetic instabilities which develop from a coupling of applied electric fields and electrical conductivity gradients induced by the ICP. The electrokinetic instability at micro-nanofluidic interfaces is important in the development of various electro-chemical-mechanical applications such as fuel cells, bio-analytical preconcentration methods, water purification/desalination and the fundamental study of ion electromigration through nanochannels and nonporous perm-selective membranes. PMID:23085964

  6. Effect of alternating bioremediation and electrokinetics on the remediation of n-hexadecane-contaminated soil

    NASA Astrophysics Data System (ADS)

    Wang, Sa; Guo, Shuhai; Li, Fengmei; Yang, Xuelian; Teng, Fei; Wang, Jianing

    2016-04-01

    This study demonstrated the highly efficient degradation of n-hexadecane in soil, realized by alternating bioremediation and electrokinetic technologies. Using an alternating technology instead of simultaneous application prevented competition between the processes that would lower their efficiency. For the consumption of the soil dissolved organic matter (DOM) necessary for bioremediation by electrokinetics, bioremediation was performed first. Because of the utilization and loss of the DOM and water-soluble ions by the microbial and electrokinetic processes, respectively, both of them were supplemented to provide a basic carbon resource, maintain a high electrical conductivity and produce a uniform distribution of ions. The moisture and bacteria were also supplemented. The optimal DOM supplement (20.5 mg·kg‑1 glucose; 80–90% of the total natural DOM content in the soil) was calculated to avoid competitive effects (between the DOM and n-hexadecane) and to prevent nutritional deficiency. The replenishment of the water-soluble ions maintained their content equal to their initial concentrations. The degradation rate of n-hexadecane was only 167.0 mg·kg‑1·d‑1 (1.9%, w/w) for the first 9 days in the treatments with bioremediation or electrokinetics alone, but this rate was realized throughout the whole process when the two technologies were alternated, with a degradation of 78.5% ± 2.0% for the n-hexadecane after 45 days of treatment.

  7. Effect of alternating bioremediation and electrokinetics on the remediation of n-hexadecane-contaminated soil

    PubMed Central

    Wang, Sa; Guo, Shuhai; Li, Fengmei; Yang, Xuelian; Teng, Fei; Wang, Jianing

    2016-01-01

    This study demonstrated the highly efficient degradation of n-hexadecane in soil, realized by alternating bioremediation and electrokinetic technologies. Using an alternating technology instead of simultaneous application prevented competition between the processes that would lower their efficiency. For the consumption of the soil dissolved organic matter (DOM) necessary for bioremediation by electrokinetics, bioremediation was performed first. Because of the utilization and loss of the DOM and water-soluble ions by the microbial and electrokinetic processes, respectively, both of them were supplemented to provide a basic carbon resource, maintain a high electrical conductivity and produce a uniform distribution of ions. The moisture and bacteria were also supplemented. The optimal DOM supplement (20.5 mg·kg−1 glucose; 80–90% of the total natural DOM content in the soil) was calculated to avoid competitive effects (between the DOM and n-hexadecane) and to prevent nutritional deficiency. The replenishment of the water-soluble ions maintained their content equal to their initial concentrations. The degradation rate of n-hexadecane was only 167.0 mg·kg−1·d−1 (1.9%, w/w) for the first 9 days in the treatments with bioremediation or electrokinetics alone, but this rate was realized throughout the whole process when the two technologies were alternated, with a degradation of 78.5% ± 2.0% for the n-hexadecane after 45 days of treatment. PMID:27032838

  8. Multi-vortical flow inducing electrokinetic instability in ion concentration polarization layer.

    PubMed

    Kim, Sung Jae; Ko, Sung Hee; Kwak, Rhokyun; Posner, Jonathan D; Kang, Kwan Hyoung; Han, Jongyoon

    2012-12-01

    In this work, we investigated multiple vortical flows inside the ion concentration polarization (ICP) layer that forms due to a coupling of applied electric fields and the semipermeable nanoporous junction between microchannels. While only a primary vortex near perm-selective membrane is traditionally known to lead to electrokinetic instability, multiple vortexes induced by the primary vortex were found to play a major role in the electrokinetic instability. The existence of multiple vortexes was directly confirmed by experiments using particle tracers and interdigitated electrodes were used to measure the local concentration profile inside the ICP layer. At larger applied electric fields, we observed aperiodic fluid motion due to electrokinetic instabilities which develop from a coupling of applied electric fields and electrical conductivity gradients induced by the ICP. The electrokinetic instability at micro-nanofluidic interfaces is important in the development of various electro-chemical-mechanical applications such as fuel cells, bio-analytical preconcentration methods, water purification/desalination and the fundamental study of ion electromigration through nanochannels and nonporous perm-selective membranes.

  9. Effect of alternating bioremediation and electrokinetics on the remediation of n-hexadecane-contaminated soil.

    PubMed

    Wang, Sa; Guo, Shuhai; Li, Fengmei; Yang, Xuelian; Teng, Fei; Wang, Jianing

    2016-01-01

    This study demonstrated the highly efficient degradation of n-hexadecane in soil, realized by alternating bioremediation and electrokinetic technologies. Using an alternating technology instead of simultaneous application prevented competition between the processes that would lower their efficiency. For the consumption of the soil dissolved organic matter (DOM) necessary for bioremediation by electrokinetics, bioremediation was performed first. Because of the utilization and loss of the DOM and water-soluble ions by the microbial and electrokinetic processes, respectively, both of them were supplemented to provide a basic carbon resource, maintain a high electrical conductivity and produce a uniform distribution of ions. The moisture and bacteria were also supplemented. The optimal DOM supplement (20.5 mg·kg(-1) glucose; 80-90% of the total natural DOM content in the soil) was calculated to avoid competitive effects (between the DOM and n-hexadecane) and to prevent nutritional deficiency. The replenishment of the water-soluble ions maintained their content equal to their initial concentrations. The degradation rate of n-hexadecane was only 167.0 mg·kg(-1)·d(-1) (1.9%, w/w) for the first 9 days in the treatments with bioremediation or electrokinetics alone, but this rate was realized throughout the whole process when the two technologies were alternated, with a degradation of 78.5% ± 2.0% for the n-hexadecane after 45 days of treatment. PMID:27032838

  10. Feasibility of electrokinetic oxygen supply for soil bioremediation purposes.

    PubMed

    Mena Ramírez, E; Villaseñor Camacho, J; Rodrigo Rodrigo, M A; Cañizares Cañizares, P

    2014-12-01

    This paper studies the possibility of providing oxygen to a soil by an electrokinetic technique, so that the method could be used in future aerobic polluted soil bioremediation treatments. The oxygen was generated from the anodic reaction of water electrolysis and transported to the soil in a laboratory-scale electrokinetic cell. Two variables were tested: the soil texture and the voltage gradient. The technique was tested in two artificial soils (clay and sand) and later in a real silty soil, and three voltage gradients were used: 0.0 (control), 0.5, and 1.0 V cm(-1). It was observed that these two variables strongly influenced the results. Oxygen transport into the soil was only available in the silty and sandy soils by oxygen diffusion, obtaining high dissolved oxygen concentrations, between 4 and 9 mg L(-1), useful for possible aerobic biodegradation processes, while transport was not possible in fine-grained soils such as clay. Electro-osmotic flow did not contribute to the transport of oxygen, and an increase in voltage gradients produced higher oxygen transfer rates. However, only a minimum fraction of the electrolytically generated oxygen was efficiently used, and the maximum oxygen transport rate observed, approximately 1.4 mgO2 L(-1)d(-1), was rather low, so this technique could be only tested in slow in-situ biostimulation processes for organics removal from polluted soils.

  11. Feasibility of electrokinetic oxygen supply for soil bioremediation purposes.

    PubMed

    Mena Ramírez, E; Villaseñor Camacho, J; Rodrigo Rodrigo, M A; Cañizares Cañizares, P

    2014-12-01

    This paper studies the possibility of providing oxygen to a soil by an electrokinetic technique, so that the method could be used in future aerobic polluted soil bioremediation treatments. The oxygen was generated from the anodic reaction of water electrolysis and transported to the soil in a laboratory-scale electrokinetic cell. Two variables were tested: the soil texture and the voltage gradient. The technique was tested in two artificial soils (clay and sand) and later in a real silty soil, and three voltage gradients were used: 0.0 (control), 0.5, and 1.0 V cm(-1). It was observed that these two variables strongly influenced the results. Oxygen transport into the soil was only available in the silty and sandy soils by oxygen diffusion, obtaining high dissolved oxygen concentrations, between 4 and 9 mg L(-1), useful for possible aerobic biodegradation processes, while transport was not possible in fine-grained soils such as clay. Electro-osmotic flow did not contribute to the transport of oxygen, and an increase in voltage gradients produced higher oxygen transfer rates. However, only a minimum fraction of the electrolytically generated oxygen was efficiently used, and the maximum oxygen transport rate observed, approximately 1.4 mgO2 L(-1)d(-1), was rather low, so this technique could be only tested in slow in-situ biostimulation processes for organics removal from polluted soils. PMID:25173714

  12. Electrokinetic removal of uranium from contaminated, unsaturated soils

    SciTech Connect

    Booher, W.F.; Lindgren, E.R.; Brady, P.V.

    1997-01-01

    Electrokinetic remediation of uranium-contaminated soil was studied in a series of laboratory-scale experiments in test cells with identical geometry using quartz sand at approximately 10 percent moisture content. Uranium, when present in the soil system as an anionic complex, could be migrated through unsaturated soil using electrokinetics. The distance that the uranium migrated in the test cell was dependent upon the initial molar ratio of citrate to uranium used. Over 50 percent of the uranium was recovered from the test cells using the citrate and carbonate complexing agents over of period of 15 days. Soil analyses showed that the uranium remaining in the test cells had been mobilized and ultimately would have been extracted. Uranium extraction exceeded 90 percent in an experiment that was operated for 37 days. Over 70 percent of the uranium was removed from a Hanford waste sample over a 55 day operating period. Citrate and carbonate ligand utilization ratios required for removing 50 percent of the uranium from the uranium-contaminated sand systems were approximately 230 moles ligand per mole uranium and 1320 moles ligand per mole uranium for the waste. Modifying the operating conditions to increasing the residence time of the complexants is expected to improved the utilization efficiency of the complexing agent.

  13. Viscoelastic effects on electrokinetic particle focusing in a constricted microchannel

    PubMed Central

    Lu, Xinyu; DuBose, John; Joo, Sang Woo; Qian, Shizhi

    2015-01-01

    Focusing suspended particles in a fluid into a single file is often necessary prior to continuous-flow detection, analysis, and separation. Electrokinetic particle focusing has been demonstrated in constricted microchannels by the use of the constriction-induced dielectrophoresis. However, previous studies on this subject have been limited to Newtonian fluids only. We report in this paper an experimental investigation of the viscoelastic effects on electrokinetic particle focusing in non-Newtonian polyethylene oxide solutions through a constricted microchannel. The width of the focused particle stream is found NOT to decrease with the increase in DC electric field, which is different from that in Newtonian fluids. Moreover, particle aggregations are observed at relatively high electric fields to first form inside the constriction. They can then either move forward and exit the constriction in an explosive mode or roll back to the constriction entrance for further accumulations. These unexpected phenomena are distinct from the findings in our earlier paper [Lu et al., Biomicrofluidics 8, 021802 (2014)], where particles are observed to oscillate inside the constriction and not to pass through until a chain of sufficient length is formed. They are speculated to be a consequence of the fluid viscoelasticity effects. PMID:25713690

  14. Laboratory scale electrokinetic remediation and geophysical monitoring of metal-contaminated marine sediments

    NASA Astrophysics Data System (ADS)

    Masi, Matteo; Pazzi, Veronica; Losito, Gabriella

    2013-04-01

    Electrokinetic remediation is an emerging technology that can be used to remove contaminants from soils and sediments. This technique relies on the application of a low-intensity electric field to extract heavy metals, radionuclides and some organic compounds. When the electric field is applied three main transport processes occur in the porous medium: electromigration, electroosmosis and electrophoresis. Monitoring of electrokinetic processes in laboratory and field is usually conducted by means of point measurements and by collecting samples from discrete locations. Geophysical methods can be very effective in obtaining high spatial and temporal resolution mapping for an adequate control of the electrokinetic processes. This study investigates the suitability of electrokinetic remediation for extracting heavy metals from dredged marine sediments and the possibility of using geophysical methods to monitor the remediation process. Among the geophysical methods, the spectral induced polarization technique was selected because of its capability to provide valuable information about the physico-chemical characteristics of the porous medium. Electrokinetic remediation experiments in laboratory scale were made under different operating conditions, obtained by varying the strength of the applied electric field and the type of conditioning agent used at the electrode compartments in each experiment. Tap water, 0.1M citric acid and 0.1M ethylenediamine tetraacetic acid (EDTA) solutions were used respectively as processing fluids. Metal removal was relevant when EDTA was used as conditioning agent and the electric potential was increased, as these two factors promoted the electroosmotic flow which is considered to be the key transport mechanism. The removal efficiencies ranged from 9.5% to 27% depending on the contaminant concerned. These percentages are likely to be raised by a further increase of the applied electric field. Furthermore, spectral induced polarization

  15. In situ soil remediation using electrokinetics

    SciTech Connect

    Buehler, M.F.; Surma, J.E.; Virden, J.W.

    1994-11-01

    Electrokinetics is emerging as a promising technology for in situ soil remediation. This technique is especially attractive for Superfund sites and government operations which contain large volumes of contaminated soil. The approach uses an applied electric field to induce transport of both radioactive and hazardous waste ions in soil. The transport mechanisms include electroosmosis, electromigration, and electrophoresis. The feasibility of using electrokinetics to move radioactive {sup 137}Cs and {sup 60}Co at the Hanford Site in Richland, Washington, is discussed. A closed cell is used to provide in situ measurements of {sup 137}Cs and {sup 60}Co movement in Hanford soil. Preliminary results of ionic movement, along with the corresponding current response, are presented.

  16. Electrokinetic Transport in Polyelectrolyte-Grafted Nanochannels

    NASA Astrophysics Data System (ADS)

    Das, Siddhartha

    2014-11-01

    We discuss here an analytical framework for describing the streaming potential generation in charged soft nanochannels in presence of a pure pressure-driven transport. Soft nanochannels are described by considering a charged polyelectrolyte layer (or PEL) resident on the nanochannel walls. We pinpoint the key dimensionless parameters that dictate the problem. We further identify that such electrokinetic transport leads to extremely efficient electrochemomechanical energy conversion associated with the generation of streaming potential. We also demonstrate that the PEL thickness as well as the depth-dependent distribution of the polymer density within the PEL need to be quantified from the balance of the elastic, volume-exclusion and electrostatic interactions - such PEL behaviour exerts non-trivial influences in the overall electrokinetic nanochannel transport.

  17. Manipulating bacteria with opto-electrokinetic methods

    NASA Astrophysics Data System (ADS)

    Wereley, Steve; Kwon, Jae-Sung; Ravindranath, Sandeep; Irudayaraj, Joseph

    2010-11-01

    Recently we developed an opto-electrokinetic method for manipulating particles and cells called Rapid Electrokinetic Patterning (REP). REP is a very fast method for manipulating thousands of particles simultaneously and controllably owing to the creation of an electrothermal vortex that transports particles rapidly and in parallel to a site determined by the focal point of a laser beam. Whether particles are trapped at the center of the vortex or not is determined by their electrical properties (conductivity and permittivity). In this talk we demonstrate that REP can be used to manipulate the bacterium Shewanella oneidensis MR-1. The bacteria are assembled into large planar arrays of organisms. The dependence of this assembly process on voltage and frequency is quantified. REP can even be used to selectively manipulate and collect live or dead bacteria.

  18. Microminiature gas chromatograph

    DOEpatents

    Yu, Conrad M.

    1996-01-01

    A microminiature gas chromatograph (.mu.GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode.

  19. Microminiature gas chromatograph

    DOEpatents

    Yu, C.M.

    1996-12-10

    A microminiature gas chromatograph ({mu}GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode. 7 figs.

  20. Comparing micellar electrokinetic chromatography and microemulsion electrokinetic chromatography for the analysis of preservatives in pharmaceutical and cosmetic products.

    PubMed

    Huang, Hsi-Ya; Lai, Yu-Cheng; Chiu, Chen-Wen; Yeh, Jui-Ming

    2003-04-18

    In this study, separation and determination of nine preservatives ranging from hydrophilic to hydrophobic properties, which are commonly used as additives in various pharmaceutical and cosmetic products, by micellar electrokinetic chromatograpy (MEKC) and microemulsion electrokinetic chromatography (MEEKC) were compared. The effect of temperature, buffer pH, and concentration of surfactant on separation were examined. In MEKC, the separation resolution of preservatives improved markedly by changing the sodium dodecyl sulfate concentration. Temperature and pH of running buffers were used mainly to shorten the magnitude of separation time. However, in order to detect all preservatives in a single run in a MEEKC system, a microemulsion of higher pH was needed. The separation resolution was improved dramatically by changing temperature, and a higher concentration of SDS was necessary for maintaining a stable microemulsion solution, therefore the separation of the nine preservatives in MEEKC took longer than in MEKC. An optimum MEKC method for separation of the nine preservatives was obtained within 9.0 min with a running buffer of pH 9.0 containing 20 mM SDS at 25 degrees C. A separation with baseline resolution was also obtained within 16 min using a microemulsion of pH 9.5 which composed of SDS, 1-butanol, and octane, and a shorter capillary column at 34 degrees C. Finally, the developed MEKC and MEEKC methods determined successfully preservatives in various cosmetic and pharmaceutical products.

  1. Effects of electrostatic correlations on electrokinetic phenomena.

    PubMed

    Storey, Brian D; Bazant, Martin Z

    2012-11-01

    The classical theory of electrokinetic phenomena is based on the mean-field approximation that the electric field acting on an individual ion is self-consistently determined by the local mean charge density. This paper considers situations, such as concentrated electrolytes, multivalent electrolytes, or solvent-free ionic liquids, where the mean-field approximation breaks down. A fourth-order modified Poisson equation is developed that captures the essential features in a simple continuum framework. The model is derived as a gradient approximation for nonlocal electrostatics of interacting effective charges, where the permittivity becomes a differential operator, scaled by a correlation length. The theory is able to capture subtle aspects of molecular simulations and allows for simple calculations of electrokinetic flows in correlated ionic fluids. Charge-density oscillations tend to reduce electro-osmotic flow and streaming current, and overscreening of surface charge can lead to flow reversal. These effects also help to explain the suppression of induced-charge electrokinetic phenomena at high salt concentrations. PMID:23214872

  2. Electrokinetic soil remediation--critical overview.

    PubMed

    Virkutyt, Jurate; Sillanpää, Mika; Latostenmaa, Petri

    2002-04-22

    In recent years, there has been increasing interest in finding new and innovative solutions for the efficient removal of contaminants from soils to solve groundwater, as well as soil, pollution. The objective of this review is to examine several alternative soil-remediating technologies, with respect to heavy metal remediation, pointing out their strengths and drawbacks and placing an emphasis on electrokinetic soil remediation technology. In addition, the review presents detailed theoretical aspects, design and operational considerations of electrokinetic soil-remediation variables, which are most important in efficient process application, as well as the advantages over other technologies and obstacles to overcome. The review discusses possibilities of removing selected heavy metal contaminants from clay and sandy soils, both saturated and unsaturated. It also gives selected efficiency rates for heavy metal removal, the dependence of these rates on soil variables, and operational conditions, as well as a cost-benefit analysis. Finally, several emerging in situ electrokinetic soil remediation technologies, such as Lasagna, Elektro-Klean, electrobioremediation, etc., are reviewed, and their advantages, disadvantages and possibilities in full-scale commercial applications are examined. PMID:12049409

  3. Electrokinetic transport in microchannels with random roughness

    SciTech Connect

    Wang, Moran; Kang, Qinjun

    2008-01-01

    We present a numerical framework to model the electrokinetic transport in microchannels with random roughness. The three-dimensional microstructure of the rough channel is generated by a random generation-growth method with three statistical parameters to control the number density, the total volume fraction, and the anisotropy characteristics of roughness elements. The governing equations for the electrokinetic transport are solved by a high-efficiency lattice Poisson?Boltzmann method in complex geometries. The effects from the geometric characteristics of roughness on the electrokinetic transport in microchannels are therefore modeled and analyzed. For a given total roughness volume fraction, a higher number density leads to a lower fluctuation because of the random factors. The electroosmotic flow rate increases with the roughness number density nearly logarithmically for a given volume fraction of roughness but decreases with the volume fraction for a given roughness number density. When both the volume fraction and the number density of roughness are given, the electroosmotic flow rate is enhanced by the increase of the characteristic length along the external electric field direction but is reduced by that in the direction across the channel. For a given microstructure of the rough microchannel, the electroosmotic flow rate decreases with the Debye length. It is found that the shape resistance of roughness is responsible for the flow rate reduction in the rough channel compared to the smooth channel even for very thin double layers, and hence plays an important role in microchannel electroosmotic flows.

  4. Electrokinetic soil remediation--critical overview.

    PubMed

    Virkutyt, Jurate; Sillanpää, Mika; Latostenmaa, Petri

    2002-04-22

    In recent years, there has been increasing interest in finding new and innovative solutions for the efficient removal of contaminants from soils to solve groundwater, as well as soil, pollution. The objective of this review is to examine several alternative soil-remediating technologies, with respect to heavy metal remediation, pointing out their strengths and drawbacks and placing an emphasis on electrokinetic soil remediation technology. In addition, the review presents detailed theoretical aspects, design and operational considerations of electrokinetic soil-remediation variables, which are most important in efficient process application, as well as the advantages over other technologies and obstacles to overcome. The review discusses possibilities of removing selected heavy metal contaminants from clay and sandy soils, both saturated and unsaturated. It also gives selected efficiency rates for heavy metal removal, the dependence of these rates on soil variables, and operational conditions, as well as a cost-benefit analysis. Finally, several emerging in situ electrokinetic soil remediation technologies, such as Lasagna, Elektro-Klean, electrobioremediation, etc., are reviewed, and their advantages, disadvantages and possibilities in full-scale commercial applications are examined.

  5. FEASIBILITY OF ELECTROKINETIC SOIL REMEDIATION IN HORIZONTAL LASAGNA CELLS

    EPA Science Inventory

    An integrated soil remediation technology called Lasagna has been developed that combines electrokinetics with treatment zones for use in low permeability soils where the rates of hydraulic and electrokinetic transport are too low to be useful for remediation of contaminants. The...

  6. Electrokinetic profiles of nonowoven cotton for absorbent incontinence material

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper discusses recent work on cotton/synthetic nonwovens, their electrokinetic analysis, and their potential use in incontinence materials. Electrokinetic analysis is useful in exploring fiber surface polarity properties, and it is a useful tool to render a snap shot of the role of fiber char...

  7. Electrokinetics over liquid/liquid interfaces

    NASA Astrophysics Data System (ADS)

    Squires, Todd M.

    2011-11-01

    Since liquid-liquid interfaces flow in response to an applied stress, one might expect electrokinetic flows at liquid-liquid interfaces to be significantly higher than over liquid-solid interfaces. The earliest predictions for the electrophoretic mobility of charged mercury drops - distinct approaches by Frumkin and Levich (1946), and Booth (1951) - differed by O (a /λD) , where a is the radius of the drop and λD is the Debye screening length. Seeking to reconcile this rather striking discrepancy, Levine (1973) showed double-layer polarization to be the key ingredient. Without a physical mechanism by which electrokinetic effects are enhanced, however, it is difficult to know how general the enhancement is - whether it holds only for liquid metal surfaces, or more generally, for all liquid/liquid surfaces. By considering a series of systems in which a planar metal strip is coated with either a liquid metal or liquid dielectric, we show that the central physical mechanism behind the enhancement predicted by Frumkin and Levich (1946) is the presence of an unmatched electrical stress upon the electrolyte-liquid interface, which establishes a Marangoni stress on the droplet surface and drives it into motion. The source of the unbalanced electrokinetic stress on a liquid metal surface is clear - metals represent equipotential surfaces, so no field exists to drive an equal and opposite force on the surface charge. This might suggest that liquid metals represent a unique system, since dielectric liquids can support finite electric fields, which might be expected to exert an electrical stress on the surface charge that balances the electric stress. We demonstrate, however, that electrical and osmotic stresses on relaxed double-layers internal to dielectric liquids precisely cancel, so that internal electrokinetic stresses generally vanish in closed, ideally polarizable liquids. The enhancement for liquid mercury drops can thus be expected quite generally over clean

  8. The investigation on cationic exchange capacity of zeolites: the use as selective ion trappers in the electrokinetic soil technique.

    PubMed

    Ursini, Ornella; Lilla, Edo; Montanari, Roberta

    2006-09-21

    The cation exchange capacity (CEC) of porous zeolites allows to adsorb in the framework cavities the cations as pollutant heavy metal ions. We investigate the CEC behaviour of different zeolites in different experimental conditions; in solution where the ion's mobility is spontaneous and free and in the electrokinetic system where the ion's mobility is driven by the electric field. The aim of this study is to investigate if the CEC is an useful property to create a special interface region of zeolites, that if placed in the electrokinetic cell, just before the cathode, could allow to capture and concentrate the heavy metallic ions, during their migrating process. The zeolite 13X investigated in the electrokinetic proofs, retains a good high ions adsorption, even if quite smaller than the relevant free solution condition and well acts as confined trap for the heavy metal ions. In fact no trace of metallic deposition are present on the electrode's surface. PMID:16716501

  9. The characterizations of rheological, electrokinetical and structural properties of ODTABr/MMT and HDTABr/MMT organoclays

    SciTech Connect

    Isci, S. Uslu, Y.O.; Ece, O.I.

    2009-05-15

    In the present paper, we have investigated as a function of surfactant concentration the rheological (yield value, plastic viscosity) and electrokinetic (mobility, zeta potential) properties of montmorillonite (MMT) dispersions. The influence of surfactants (Octadeccyltrimethylammonium bromide, ODTABr and Hexadecyltrimethylammonium bromide, HDTABr) on dispersions of Na-activated bentonite was evaluated by rheological and electrokinetic measurements, and X-ray diffraction (XRD) studies. The interactions between clay minerals and surfactants in water-based Na-activated MMT dispersions (2 wt.%) were examined in detail using rheologic parameters, such as viscosity, yield point, apparent and plastic viscosity, hysteresis area, and electrokinetic parameters of mobility and zeta potentials, and XRD also analyses helped to determine swelling properties of d-spacings. MMT and organoclay dispersions showed Bingham Plastic flow behavior. The zeta potential measurements displayed that the surfactant molecules hold on the clay particle surfaces and the XRD analyses displayed that they get into the basal layers.

  10. Determination of plant stanols and plant sterols in phytosterol enriched foods with a gas chromatographic-flame ionization detection method: NMKL collaborative study.

    PubMed

    Laakso, Päivi H

    2014-01-01

    This collaborative study with nine participating laboratories was conducted to determine the total plant sterol and/or plant stanol contents in phytosterol fortified foods with a gas chromatographic method. Four practice and 12 test samples representing mainly commercially available foodstuffs were analyzed as known replicates. Twelve samples were enriched with phytosterols, whereas four samples contained only natural contents of phytosterols. The analytical procedure consisted of two alternative approaches: hot saponification method, and acid hydrolysis treatment prior to hot saponification. As a result, sterol/stanol compositions and contents in the samples were measured. The amounts of total plant sterols and total plant stanols varying from 0.005 to 8.04 g/100 g product were statistically evaluated after outliers were eliminated. The repeatability RSD (RSDr) varied from 1.34 to 17.13%. The reproducibility RSD (RSDR) ranged from 3.03 to 17.70%, with HorRat values ranging from 0.8 to 2.1. When only phytosterol enriched food test samples are considered, the RSDr ranged from 1.48 to 6.13%, the RSD, ranged from 3.03 to 7.74%, and HorRat values ranged from 0.8 to 2.1. Based on the results of this collaborative study, the study coordinator concludes the method is fit for its purpose.

  11. A bridging study for oxytetracycline in the edible fillet of rainbow trout: Analysis by a liquid chromatographic method and the official microbial inhibition assay

    USGS Publications Warehouse

    Stehly, G.R.; Gingerich, W.H.; Kiessling, C.R.; Cutting, J.H.

    1999-01-01

    Oxytetracycline (OTC) is a drug approved by the U.S. Food and Drug Administration (FDA) to control certain diseases in salmonids and catfish. OTC is also a likely control agent for diseases of other fish species and for other diseases of salmonids and catfish not currently on the label. One requirement for FDA to extend and expand the approval of this antibacterial agent to other fish species is residue depletion studies. The current regulatory method for OTC in fish tissue, based on microbial inhibition, lacks sensitivity and specificity. To conduct residue depletion studies for OTC in fish with a liquid chromatographic method, a bridging study was required to determine its relationship with the official microbial inhibition assay. Triplicate samples of rainbow trout fillet tissue fortified with OTC at 0.3, 0.6, 1.2, 2.4, 4.8, and 9.6 ppm and fillet tissue with incurred OTC at approximately 0.75, 1.5, and 3.75 ppm were analyzed by high-performance liquid chromatography (HPLC) and the microbial inhibition assay. The results indicated that the 2 methods are essentially identical in the tested range, with mean coefficients of variation of 1.05% for the HPLC method and 3.94% for the microbial inhibition assay.

  12. High ionic strength electrokinetics of melamine-formaldehyde latex.

    PubMed

    Kosmulski, Marek; Dahlsten, Per; Próchniak, Piotr; Rosenholm, Jarl B

    2006-09-15

    The electrokinetic potential of melamine-formaldehyde latex at high ionic strengths was measured by means of two different instruments. The present study confirms that the zeta potentials in 1 M 1-1 electrolyte solutions can be as high as +/-20 mV. The IEP of latex at low ionic strengths was at pH 11. The increase in the electrolyte concentration induced a shift in the IEP to low pH for all studied salts, and this indicates specific adsorption of the anions. The magnitude of the shift depends chiefly on the nature of the anion and increases in the series Cl < NO(3) = Br < I, and the nature of the cation (Li, Na, K, Cs) plays a rather insignificant role.

  13. Can an electro-kinetic mechanism explain artificial earthquakes?

    NASA Astrophysics Data System (ADS)

    Cyr, Guillaume; Glover, Paul; Novikov, Victor

    2010-05-01

    Researchers of the Joint Institute for High Temperatures of the Russian Academy of Sciences have carried out a large number of current injection experiments using a 4.2 km long dipole at the Bishkek Research Station in the Chu valley area of the Kyrgyz mountains (northern Tien Shan). The current is generated using Pulsed Magneto-Hydrodynamic (MHD) generators that can produce 2800 amperes at 1350 volts for up to 12.1 seconds. They have found that the number of earthquakes in the region within 150 km of the injection site increased by over 10 standard deviations of the background seismicity. The probability of this occurring by chance is only one in every thousand million million (10^15) measurements. It is certain, therefore, that we can generate earthquakes by current injection. However, no satisfactory physical mechanism for it currently exists. Paul Glover has suggested that an electro-kinetic mechanism may be the missing causal link. In his theory the injected current creates a three-dimensional electric field in the subsurface. The electro-kinetic mechanism uses the electric field to move the pore fluid at depth. If the pore fluid flows into a fault zone it may accumulate and transiently raise the pore fluid pressure within the fault zone. It is known that increases of pore fluid pressure within fault zones more than a critical pressure of 0.05 MPa are sufficient to trigger an earthquake if the fault has sufficient accumulated strain. Earthquakes are therefore possible while the pore fluid pressure is over the critical pressure. While the electro-kinetic drive has been well studied around the world, it is uncertain if the mechanism can provide fluid pressures sufficient to trigger earthquakes up to 150 km from the injection point. In this work we present two dimensional numerical modelling of the proposed coupled mechanism using a finite element approach and using the software package Comsol Multiphysics. The initial results are promising and indicate that (i

  14. Application of liquid chromatographic/tandem mass spectrometric method to a urinary excretion study of subutinib and active metabolite in human urine.

    PubMed

    Ding, Li-kun; Yang, Lin; Gao, Xiao-hua; Chen, Su-ning; Jia, Na; Li, Xue-qing; Zhou, Lun; Hang, Tai-jun; Wen, Ai-dong

    2016-04-01

    A novel and selective liquid chromatographic-mass spectrometric method (LC-MS/MS) has been established and validated for simultaneous determination of subutinib and active metabolite in human urine. Urine samples were extracted by liquid-liquid extraction with ethyl acetate and separated on a Wondasil C18 (150 × 2.1 mm, 3.5 µm), with methanol-0.2% formic acid solution (73:27, v/v) as mobile phase at flow rate of 0.2 mL/min. The linear range was 0.5000-200.0 ng/mL for subutinib and active metabolite, with a lower limit of quantitation of 0.5000 ng/mL. Intra- and inter-run precisions were all <11.8 and 14.3%, and the accuracies were all <4.5 and 5.4%, with the extraction recoveries 88.8-97.5 and 93.8-99.4% for the two analytes, respectively. The carryover values were all <15% for the two anayltes. The method was successfully applied to study urinary excretion of subutinib and active metabolite in human after oral administration of subutinib maleate capsules in fed and fasting states.

  15. Separation and determination of podophyllum lignans by micellar electrokinetic chromatography.

    PubMed

    Liu, S; Tian, X; Chen, X; Hu, Z

    2001-08-31

    A micellar electrokinetic chromatography method was established for the quantitative analysis of seven podophyllum lignans in Podophyllum emodi Wall. var. chinesis sprague. The optimum buffer system was 10 mM NaH2PO4-5 mM borate-100 mM sodium dodecylsulfate-30% isopropanol (pH 7.20). Voltage was 18 kV and detection at 214 nm. The second derivative chromatogram was used to determine a low-content component and those not fully separated from adjacent ones. The RSD values of migration times and peak areas were <2.2 and <5.5%, respectively. The effects of several CE parameters on the resolutions were studied systematically.

  16. Electrokinetic ion transport in confined micro-nanochannel.

    PubMed

    Wang, Junyao; Liu, Chong; Xu, Zheng

    2016-03-01

    In this paper, a confined micronanochannel is presented to concentrate ions in a restricted zone. A general model exploiting the Poisson-Nernst-Plank equations coupled with the Navier-Stokes equation is employed to simulate the electrokinetic ion transport. The influences of the micronanochannel dimension and the surface charge density on the potential distribution, the ion concentration, and the fluid flow are investigated. The numerical results show that the potential drop depends mainly on the nanochannel, instead of the confined channel. Both decreasing the width and increasing the length enhance the ion enrichment performance. For a given nanochannel, ultimate value of ion concentration may be determined by the potential at the center point of the nanochannel. The study also shows that the enrichment stability can be improved by increasing the micronanochannel width, decreasing the micronanochannel length and reducing the surface charge density. PMID:26995194

  17. Electrokinetic Characteristics of Calcined Kaolinite in Aqueous Electrolytic Solutions

    NASA Astrophysics Data System (ADS)

    Chen, Tianxing; Zhao, Yunliang; Li, Hongliang; Liu, Jia; Song, Shaoxian

    2015-03-01

    In this work, the electrokinetic characteristics of calcined kaolinite in aqueous solutions has been studied in the presence of the electrolytes of NaCl, KCl, NH4Cl, NaNO3, MgCl2, CaCl2 and AlCl3, through electrophoretic measurement. The experimental results have shown that the zeta potential was closely dependent on the valence and concentration of the electrolytic cations, but not on the type of the cations. The higher the valence and the concentration were, the stronger the impact to the zeta potential was. Al3+ could reverse the potential sign from negative to positive. In addition, it was found that the monovalent anions of Cl- and NO3- made a big difference to the zeta potential at the same dosage.

  18. Electrokinetic transport in unsteady flow through peristaltic microchannel

    NASA Astrophysics Data System (ADS)

    Tripathi, Dharmendra; Mulchandani, Janak; Jhalani, Shubham

    2016-04-01

    We analyze the electrokinetic transport of aqueous electrolyte fluids with Newtonian model in presence of peristalsis through microchannel. Debye-Hückel linearization is employed to simplify the problem. Low Reynolds number and large wavelength approximations are taken into account subjected to microfluidics applications. Electrical double layer (EDL) is considered very thin and electroosmotic slip velocity (i.e. Helmholtz-Smoluchowski velocity) at the wall is subjected to study the effect of applied electrical field. The solutions for axial velocity and pressure difference along the channel length are obtained analytically and the effects of adding and opposing the flow by applied electric field have been discussed. It is revealed that the axial velocity and pressure gradient enhances with adding electric field and an opposite behavior is found in the flow direction on opposing the electric field. These results may also help towards designing organ-on-a-chip like devices for better drug design.

  19. Cyclodextrin-mediated enantioseparation in microemulsion electrokinetic chromatography.

    PubMed

    Borst, Claudia; Holzgrabe, Ulrike

    2013-01-01

    Chiral separation by means of cyclodextrins has a long-standing tradition in capillary electrophoresis techniques. Here we present a chiral method utilizing the recently introduced microemulsion electrokinetic chromatography. The microemulsion consisting of 1.0% SDS, 4.0% 1-butanol, 3.0% 2-propanol, 0.5% ethylacetate, and 91.5% 20 mM phosphate buffer pH 2.5 serves as a pseudostationary phase which is complemented by sulfated cyclodextrin as a second phase. The analytes partition between the aqueous running buffer and both pseudostationary phases, the oil droplets and the cyclodextrins. Enantiomers are separated due to the formation of transient diastereomeric complexes with the cyclodextrins. For the racemates of ephedrine derivatives studied here sulfated β-cyclodextrin was successfully applied. The method is appropriate to resolve an entire series of chiral phenethylamines and can be used for separation of the racemates and impurity profiling, e.g., the determination of the enantiomeric excess.

  20. On-line preferential solvation studies of polymers by coupled chromatographic-Fourier transform infrared spectroscopic flow-cell technique.

    PubMed

    Malanin, M; Eichhorn, K-J; Lederer, A; Treppe, P; Adam, G; Fischer, D; Voigt, D

    2009-12-18

    Qualitative and quantitative comparison between liquid chromatography (LC) and LC coupled with Fourier transform infrared spectroscopy (LC-FTIR) to evaluate preferential solvation phenomenon of polymers in a mixed solvent has been performed. These studies show that LC-FTIR technique leads to detailed structural information without the requirement for determination of additional parameters for quantitative analysis except calibration. Appropriate experimental conditions for preferential solvation study have been established by variation of polymer concentration, molar mass and eluent content.

  1. Electrokinetic characteristics of HSA dimer and its monolayers at mica.

    PubMed

    Kujda, Marta; Adamczyk, Zbigniew; Zapotoczny, Szczepan; Kowalska, Ewa

    2015-12-01

    Human serum albumin (HSA) dimer was synthesized in a reaction of the monomer with 1,6-bis(maleimido)hexane (BMH) cross-linker. Thorough physicochemical characteristics of the dimer were performed. They comprised the diffusion coefficient, hydrodynamic diameter, electrophoretic mobility as a function of pH, isoelectric point and electrokinetic charge. The adsorption of the dimer molecules at mica was studied using the atomic force microscopy (AFM) and in situ streaming potential measurements. The kinetics of adsorption was determined by a direct AFM imaging of single molecules over various substrate areas and interpreted in terms of the random sequential adsorption model. These results were consistent with streaming potential measurements carried out for the parallel-plate channel flow. It was also shown by these measurements that the desorption of the monomer under flow conditions was negligible. In this way, the amount of irreversibly bound dimer was quantitatively evaluated to be 0.5 mgm(-2) for ionic strength of 0.01 and pH 3.5 that is similar that to previous result obtained for the albumin monomer. This indicates that the dimer adsorption occurs mostly in the side-on orientation. Finally, the electrokinetic characteristics of the dimer monolayers on mica were performed by the streaming potential method. It was observed that for lower pHs the zeta potential of monolayers is much lower than the bulk zeta potential of the dimer molecules. This was attributed to a heterogeneous charge distribution. It was concluded that the well-characterized HSA dimer monolayers can be used for quantitatively determining ligand and drug binding that has an essential practical significance. PMID:26613862

  2. Electrokinetic characteristics of HSA dimer and its monolayers at mica.

    PubMed

    Kujda, Marta; Adamczyk, Zbigniew; Zapotoczny, Szczepan; Kowalska, Ewa

    2015-12-01

    Human serum albumin (HSA) dimer was synthesized in a reaction of the monomer with 1,6-bis(maleimido)hexane (BMH) cross-linker. Thorough physicochemical characteristics of the dimer were performed. They comprised the diffusion coefficient, hydrodynamic diameter, electrophoretic mobility as a function of pH, isoelectric point and electrokinetic charge. The adsorption of the dimer molecules at mica was studied using the atomic force microscopy (AFM) and in situ streaming potential measurements. The kinetics of adsorption was determined by a direct AFM imaging of single molecules over various substrate areas and interpreted in terms of the random sequential adsorption model. These results were consistent with streaming potential measurements carried out for the parallel-plate channel flow. It was also shown by these measurements that the desorption of the monomer under flow conditions was negligible. In this way, the amount of irreversibly bound dimer was quantitatively evaluated to be 0.5 mgm(-2) for ionic strength of 0.01 and pH 3.5 that is similar that to previous result obtained for the albumin monomer. This indicates that the dimer adsorption occurs mostly in the side-on orientation. Finally, the electrokinetic characteristics of the dimer monolayers on mica were performed by the streaming potential method. It was observed that for lower pHs the zeta potential of monolayers is much lower than the bulk zeta potential of the dimer molecules. This was attributed to a heterogeneous charge distribution. It was concluded that the well-characterized HSA dimer monolayers can be used for quantitatively determining ligand and drug binding that has an essential practical significance.

  3. Concentric-flow electrokinetic injector enables serial crystallography of ribosome and photosystem II.

    PubMed

    Sierra, Raymond G; Gati, Cornelius; Laksmono, Hartawan; Dao, E Han; Gul, Sheraz; Fuller, Franklin; Kern, Jan; Chatterjee, Ruchira; Ibrahim, Mohamed; Brewster, Aaron S; Young, Iris D; Michels-Clark, Tara; Aquila, Andrew; Liang, Mengning; Hunter, Mark S; Koglin, Jason E; Boutet, Sébastien; Junco, Elia A; Hayes, Brandon; Bogan, Michael J; Hampton, Christina Y; Puglisi, Elisabetta V; Sauter, Nicholas K; Stan, Claudiu A; Zouni, Athina; Yano, Junko; Yachandra, Vittal K; Soltis, S Michael; Puglisi, Joseph D; DeMirci, Hasan

    2016-01-01

    We describe a concentric-flow electrokinetic injector for efficiently delivering microcrystals for serial femtosecond X-ray crystallography analysis that enables studies of challenging biological systems in their unadulterated mother liquor. We used the injector to analyze microcrystals of Geobacillus stearothermophilus thermolysin (2.2-Å structure), Thermosynechococcus elongatus photosystem II (<3-Å diffraction) and Thermus thermophilus small ribosomal subunit bound to the antibiotic paromomycin at ambient temperature (3.4-Å structure). PMID:26619013

  4. Concentric-flow electrokinetic injector enables serial crystallography of ribosome and photosystem II.

    PubMed

    Sierra, Raymond G; Gati, Cornelius; Laksmono, Hartawan; Dao, E Han; Gul, Sheraz; Fuller, Franklin; Kern, Jan; Chatterjee, Ruchira; Ibrahim, Mohamed; Brewster, Aaron S; Young, Iris D; Michels-Clark, Tara; Aquila, Andrew; Liang, Mengning; Hunter, Mark S; Koglin, Jason E; Boutet, Sébastien; Junco, Elia A; Hayes, Brandon; Bogan, Michael J; Hampton, Christina Y; Puglisi, Elisabetta V; Sauter, Nicholas K; Stan, Claudiu A; Zouni, Athina; Yano, Junko; Yachandra, Vittal K; Soltis, S Michael; Puglisi, Joseph D; DeMirci, Hasan

    2016-01-01

    We describe a concentric-flow electrokinetic injector for efficiently delivering microcrystals for serial femtosecond X-ray crystallography analysis that enables studies of challenging biological systems in their unadulterated mother liquor. We used the injector to analyze microcrystals of Geobacillus stearothermophilus thermolysin (2.2-Å structure), Thermosynechococcus elongatus photosystem II (<3-Å diffraction) and Thermus thermophilus small ribosomal subunit bound to the antibiotic paromomycin at ambient temperature (3.4-Å structure).

  5. Electro-kinetic dewatering of oily sludges.

    PubMed

    Yang, Lin; Nakhla, George; Bassi, Amarjeet

    2005-10-17

    An oily sludge from a rendering facility was treated using electro-kinetic (EK) techniques employing two different experimental designs. The bench scale used vertical electrodes under different operational conditions, i.e. varied electrode spacing at 4, 6 and 8 cm with electric potential of 10, 20 and 30 V, respectively. The highest water removal efficiency (56.3%) at bench scale was achieved at a 4 cm spacing and 30 V. Comparison of the water removal efficiency (51.9%) achieved at the 20 V at 4 cm spacing showed that power consumption at 30 V was 1.5 times larger than that at 20 V, suggesting a further increase of electric potential is unnecessary. The solids content increased from an initial 5 to 11.5 and 14.1% for 20 and 30 V, respectively. The removal of oil and grease (O&G) was not significant at this experimental design. Another larger scale experiment using a pair of horizontal electrodes in a cylinder with 15 cm i.d. was conducted at 60 V at an initial spacing of 22 cm. More than 40.0% of water was removed and a very efficient oil separation from the sludge was achieved indicating the viability of electro-kinetic recovery of oil from industrial sludge.

  6. Electrokinetic removal of caesium from kaolin.

    PubMed

    Al-Shahrani, S S; Roberts, E P L

    2005-06-30

    Soil, in the form of kaolin and a sample of natural soil from an industrial site, was artificially contaminated with caesium and subjected to electrokinetic treatment. The effect of catholyte pH control on the process was investigated using different acids to control the catholyte pH. During treatment the in situ pH distribution, the current flow, and the potential distribution were monitored. At the end of the treatment the pore fluid conductivity and the caesium concentration distribution was measured. The results of these experiments showed that for caesium contamination, catholyte pH control is essential in order to create a suitable environment throughout the soil to enable contaminant removal. It was found that the type of acid used to control the catholyte pH affected the rate of caesium removal (nitric, sulphuric, acetic and citric acids were tested). All of the acids tested were effective, but the highest caesium extraction was achieved when nitric acid was used to control the catholyte pH. The relatively high adsorption capacity of the soil for caesium was found to significantly reduce the rate of removal. After 240 h of treatment at 1 Vcm(-1) (using sulphuric acid to control the catholyte pH), less than 80% of the caesium was removed from a 30 cm long sample of kaolin. Electrokinetic treatment of the industrial soil sample was slower than for the kaolin, but a significant extraction rate for caesium was achieved.

  7. Integration of gas chromatographs into the Federal Highway Administration/Environmental Protection Agency near road MSAT study in Las Vegas, NV

    EPA Science Inventory

    This paper documents the technical evaluation of a semi-continuous gas chromatograph (GC) for the measurement of benzene and 1,33butadiene in the near road environment. This paper will also consider the some of the non-technical implications associated with the operation of a GC ...

  8. Study of the Behaviors of Gunshot Residues from Spent Cartridges by Headspace Solid-Phase Microextraction-Gas Chromatographic Techniques.

    PubMed

    Chang, Kah Haw; Yew, Chong Hooi; Abdullah, Ahmad Fahmi Lim

    2015-07-01

    Gunshot residues, produced after shooting activity, have acquired their importance in analysis due to the notoriety of firearms-related crimes. In this study, solid-phase microextraction was performed to extract the headspace composition of spent cartridges using 85-μm polyacrylate fiber at 66°C for 21 min. Organic compounds, that is, naphthalene, 2,6-dinitrotoluene, 2,4-dinitrotoluene, diphenylamine, and dibutyl phthalate were detected and analyzed by gas chromatography-flame ionization detection technique. Evaluation of chromatograms for diphenylamine, dibutyl phthalate, and naphthalene indicates the period after a gunshot was discharged, whether it was 1 days, 2-4 days, <5 days, 10 days, 20 days, or more than 30 days ago. This study revealed the potential effects of environmental factors such as occasional wind blow and direct sunlight on the estimation of time after spent cartridges were discharged. In conclusion, we proposed reliable alternative in analyzing the headspace composition of spent cartridges in a simulated crime scene. PMID:25771708

  9. Numerical evaluation of voltage gradient constraints on electrokinetic injection of amendments

    NASA Astrophysics Data System (ADS)

    Wu, Ming Zhi; Reynolds, David A.; Prommer, Henning; Fourie, Andy; Thomas, David G.

    2012-03-01

    A new numerical model is presented that simulates groundwater flow and multi-species reactive transport under hydraulic and electrical gradients. Coupled into the existing, reactive transport model PHT3D, the model was verified against published analytical and experimental studies, and has applications in remediation cases where the geochemistry plays an important role. A promising method for remediation of low-permeability aquifers is the electrokinetic transport of amendments for in situ chemical oxidation. Numerical modelling showed that amendment injection resulted in the voltage gradient adjacent to the cathode decreasing below a linear gradient, producing a lower achievable concentration of the amendment in the medium. An analytical method is derived to estimate the achievable amendment concentration based on the inlet concentration. Even with low achievable concentrations, analysis showed that electrokinetic remediation is feasible due to its ability to deliver a significantly higher mass flux in low-permeability media than under a hydraulic gradient.

  10. Validated high performance thin layer chromatographic method for simultaneous quantification of major iridoids in Vitex trifolia and their antioxidant studies.

    PubMed

    Tiwari, Neerja; Luqman, Suaib; Masood, Nusrat; Gupta, Madan M

    2012-03-01

    Negundoside (1), agnuside (2) and 6'-p-hydroxy benzoyl mussaenosidic acid (3) are known bioactive metabolites in Vitex trifolia. In the present study a simple precise and reproducible method was developed for simultaneous quantitation of NS (1), AS (2) and HMA (3) and the antioxidant capacity of above markers has also been determined. Marker compounds have been resolved using silica gel 60 F(254) plates, petroleum ether (60-80)/toluene/acetone/water (10:10:80:2 v/v/v/v) as the mobile phases. The method does not employ any derivatisation procedure and can be used as a quality control tool for routine analysis of drugs V. trifolia and V. negundo together with their commercial extracts. NS (1), AS (2) and HMA (3) showed significant activity in DPPH and NO radical scavenging assays.

  11. Application of a liquid chromatographic/tandem mass spectrometric method to a urinary excretion study of rabeprazole and two of its metabolites in healthy human urine.

    PubMed

    Lu, Chengtao; Jia, Yanyan; Song, Ying; Li, Xueqing; Sun, Yuan; Zhao, Jinyi; Wang, Shan; Shi, Lei; Wen, Aidong; Ding, Li

    2015-04-15

    To study urinary excretion properties of rabeprazole and two of its metabolites, i.e. rabeprazole thioether and desmethyl rabeprazole thioether in human urine, a sensitive, selective, accurate and precise method for the quantification of rabeprazole and two of its metabolites using a liquid chromatographic/tandem mass spectrometric method has been developed and validated. Starting with a 200 μL urine aliquot, a general sample preparation was performed using protein precipitation with methanol. Analytes were separated on a Dikma Inspire™ C18 column (150 mm × 2.1mm, 5 μm) using a mixture of methanol and aqueous 10mM ammonium acetate buffer containing 0.05% formic acid (55:45, v/v) as mobile phase. Linearity was obtained over the concentration range of 0.1446-96.38 ng/mL, 0.3198-319.8 ng/mL and 0.05160-82.53 ng/mL for rabeprazole, rabeprazole thioether, desmethyl rabeprazole thioether in human urine, respectively. The fully validated method was applied to a urine excretion study of rabeprazole sodium administered as a 30 min intravenous infusion for the first time. The calculated cumulative urinary recovery just reached 0.04745‰, 1.272‰ and 0.1631‰ of dose within 24h post-dose for rabeprazole, rabeprazole thioether, and desmethyl rabeprazole thioether, respectively, after intravenous infusion administration, indicating that rabeprazole and its two main metabolites undergo substantial non-renal elimination in healthy Chinese volunteers. PMID:25755073

  12. Gas chromatographic-mass spectrometric study of the oil fractions produced by microwave-assisted pyrolysis of different sewage sludges.

    PubMed

    Domínguez, A; Menéndez, J A; Inguanzo, M; Bernad, P L; Pis, J J

    2003-09-19

    The pyrolysis of sewage sludge was studied in a microwave oven using graphite as microwave absorber. The pyrolysis temperature ranged from 800 to 1000 degrees C depending on the type of sewage sludge. A conventional electrical furnace was also employed in order to compare the results obtained with both methods. The pyrolysis oils were trapped in a series of condensers and their characteristics such as elemental analysis and calorific value were determined and compared with those of the initial sludge. The oil composition was analyzed by GC-MS. The oils from the microwave oven had n-alkanes and 1-alkenes, aromatic compounds, ranging from benzene derivatives to polycyclic aromatic hydrocarbons (PAHs), nitrogenated compounds, long chain aliphatic carboxylic acids, ketones and esters and also monoterpenes and steroids. The oil from the electric oven was composed basically of PAHs such as naphthalene, acenapthylene, phenanthrene, fluoranthene, benzo[a]anthracene, benzofluoranthenes, benzopyrenes, indenepyrene, benzo[ghi]perylene, and anthanthrene. In contrast, these compounds were not produced in the case of microwave-assisted pyrolysis.

  13. A simple chromatographic method for determining norfloxacin and enoxacin in pharmacokinetic study assessing CYP1A2 inhibition.

    PubMed

    Kobayashi, Toshimi; Homma, Masato; Momo, Kenji; Kobayashi, Daisuke; Kohda, Yukinao

    2011-04-01

    We developed a simple assay method for the determination of serum and urine norfloxacin and enoxacin using reversed-phase high-performance liquid chromatography and perchloric acid precipitation for sample pre-treatment. Optimized conditions can permit detection of norfloxacin and enoxacin in the same chromatogram, so either compound can be used as an internal standard for another determinant. Supernatants of the precipitated samples were analyzed by the octadecylsilyl silica-gel column under ambient temperature and an ultraviolet wavelength of 272  nm. A mobile phase solvent consisting of 20 mm sodium dihydrogenphosphate (pH 3.0) and acetonitrile (85:15, v/v) was pumped at a flow rate of 1.0 mL/min. The calibration curves for norfloxacin and enoxacin at a concentration of 62.5-1000 ng/mL for serum and 250-4000 ng/mL for urine were linear (r > 0.9997). The recoveries of norfloxacin and enoxacin from serum and urine were >94% with the coefficient of variations (CV) <5%. The CVs for intra- and inter-day assay of norfloxacin and enoxacin were <4.2 and <5.5%, respectively. This method can be applied to the pharmacokinetic study of norfloxacin and enoxacin after repeated administration to assess changes in CYP1A2 activity in healthy subjects.

  14. Zeta potential of soils with surfactants and its relevance to electrokinetic remediation.

    PubMed

    Kaya, Abidin; Yukselen, Yeliz

    2005-04-11

    There are numerous studies on the application of electrokinetic decontamination technique to remediate heavy metal contaminated fine-grained soils. In recent studies, surfactants have been used to increase the efficiency of contaminant removal. However, there is limited data available on how physicochemical parameters such as zeta potential (zeta) of soils changes in the presence of surfactants. Understanding the zeta potential variations of soils with surfactant addition is important because it controls the direction and magnitude of electro-osmotic permeability, which plays important role on the efficiency of electrokinetic remediation. In this study, zeta potentials of kaolinite, montmorillonite and quartz powder with Li+, Ca+2, Cu+2, Pb+2 and Al+3 in the presence of anionic, cationic and non-ionic surfactants were determined. The results indicate that anionic surfactants produce negative zeta potentials. The other surfactants produce both positive and negative zeta potentials depending on soil type and ion present in the system. The results also indicate that the zeta potential of kaolinite and quartz powder with surfactants showed similar trends; however, the absolute magnitude of the zeta potential of quartz powder is higher than that of kaolinite. The zeta potential of montmorillonite commonly shows a different trend from those of kaolinite and quartz powder. Based on the test results, it is recommended that zeta potential of soils be determined before the electrokinetic decontamination in order to maximize the efficiency of the technique. PMID:15811672

  15. Ex-situ field application of electrokinetics for remediation of shooting-range soil.

    PubMed

    Lee, Keun-Young; Kim, Hyun-A; Lee, Woo-Chun; Kim, Soon-Oh; Lee, Jong-Un; Kwon, Young-Ho; Kim, Kyoung-Woong

    2012-01-01

    Electrokinetic process for remediation of a shooting-range site was evaluated in this study. By field operation for 100 days, the newly designed electrokinetic system was evaluated for process stability, performance, and efficiency. The field site of this study was an abandoned military shooting range located in the Civilian Control Line of South Korea. The target area, only, was heavily contaminated by Pb and Cu to a depth of 0.5 m. After dry-sieving of the field soil to separate particulate Pb, two cells in a hexagonal (two-dimensional) arrangement, including ten anodes outside the cell and two cathodes in the middle, were prepared. The pH of each electrolyte was adjusted by use of concentrated HNO(3), resulting in acid-enhanced electrokinetics. The monitoring results indicated that overall removal of heavy metals (Pb, Cu) was achieved, and that both heavy metals were removed from outside the cell. The average final efficiency of removal of Pb and Cu was 39.5 ± 35 and 63.8 ± 12%, respectively. Although the feasibility of this system was confirmed, for commercialization of the process confirmed drawbacks must be improved by further study.

  16. Ex-situ field application of electrokinetics for remediation of shooting-range soil.

    PubMed

    Lee, Keun-Young; Kim, Hyun-A; Lee, Woo-Chun; Kim, Soon-Oh; Lee, Jong-Un; Kwon, Young-Ho; Kim, Kyoung-Woong

    2012-01-01

    Electrokinetic process for remediation of a shooting-range site was evaluated in this study. By field operation for 100 days, the newly designed electrokinetic system was evaluated for process stability, performance, and efficiency. The field site of this study was an abandoned military shooting range located in the Civilian Control Line of South Korea. The target area, only, was heavily contaminated by Pb and Cu to a depth of 0.5 m. After dry-sieving of the field soil to separate particulate Pb, two cells in a hexagonal (two-dimensional) arrangement, including ten anodes outside the cell and two cathodes in the middle, were prepared. The pH of each electrolyte was adjusted by use of concentrated HNO(3), resulting in acid-enhanced electrokinetics. The monitoring results indicated that overall removal of heavy metals (Pb, Cu) was achieved, and that both heavy metals were removed from outside the cell. The average final efficiency of removal of Pb and Cu was 39.5 ± 35 and 63.8 ± 12%, respectively. Although the feasibility of this system was confirmed, for commercialization of the process confirmed drawbacks must be improved by further study. PMID:21858453

  17. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, Don D.

    1985-01-01

    A chromatographic system that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a non-transparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extremely low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  18. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, D.D.

    A chromatographic system is described that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a nontransparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extreme low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  19. Studies on the adsorption of cell impurities from plasmid-containing lysates to phenyl boronic acid chromatographic beads.

    PubMed

    Gomes, A Gabriela; Azevedo, Ana M; Aires-Barros, M Raquel; Prazeres, D Miguel F

    2011-12-01

    Plasmid DNA (pDNA) is purified directly from alkaline lysis-derived Escherichia coli (E. coli) lysates by phenyl boronate (PB) chromatography. The method explores the ability of PB ligands to bind covalently, but reversibly, to cis-diol-containing impurities like RNA and lipopolysaccharides (LPS), leaving pDNA in solution. In spite of this specificity, cis-diol free species like proteins and genomic DNA (gDNA) are also removed. This is a major advantage since the process is designed to keep the target pDNA from binding. The focus of this paper is on the study of the secondary interactions between the impurities (RNA, gDNA, proteins, LPS) in a pDNA-containing lysate and 3-amino PB controlled pore glass (CPG) matrices. Runs were designed to evaluate the role of adsorption buffer composition, feed type (pH, salt content), CPG matrix and sample pretreatment (RNase A, isopropanol precipitation). Water was chosen as the adsorption buffer over MgCl(2) solutions since it maximised pDNA yield (96.2±4.9%) and protein removal (61.3±3.0%), while providing for a substantial removal of RNA (65.5±3.5%) and gDNA (44.7±14.1%). Although the use of pH 3.5 maximised removal of impurities (~75%), the best compromise between plasmid yield (~96%) and RNA clearance (~60-70%) was obtained for a pH of 5.2. Plasmid yield was maximal (>96%) when the concentration of acetate and potassium ions in the incoming lysate feed were 1.7 M and 1.0 M, respectively. The pre-treatment of lysates with RNase A deteriorated the performance since the resulting oligoribonucleotides lack the cis-diol group at their 3' termini. Overall, the results support the idea that charge transfer interactions between the boron atom at acidic pH and electron donor groups in the aromatic bases of nucleic acids and side residues of proteins are responsible for the non-specific removal of gDNA, RNA and proteins.

  20. Studies on the adsorption of cell impurities from plasmid-containing lysates to phenyl boronic acid chromatographic beads.

    PubMed

    Gomes, A Gabriela; Azevedo, Ana M; Aires-Barros, M Raquel; Prazeres, D Miguel F

    2011-12-01

    Plasmid DNA (pDNA) is purified directly from alkaline lysis-derived Escherichia coli (E. coli) lysates by phenyl boronate (PB) chromatography. The method explores the ability of PB ligands to bind covalently, but reversibly, to cis-diol-containing impurities like RNA and lipopolysaccharides (LPS), leaving pDNA in solution. In spite of this specificity, cis-diol free species like proteins and genomic DNA (gDNA) are also removed. This is a major advantage since the process is designed to keep the target pDNA from binding. The focus of this paper is on the study of the secondary interactions between the impurities (RNA, gDNA, proteins, LPS) in a pDNA-containing lysate and 3-amino PB controlled pore glass (CPG) matrices. Runs were designed to evaluate the role of adsorption buffer composition, feed type (pH, salt content), CPG matrix and sample pretreatment (RNase A, isopropanol precipitation). Water was chosen as the adsorption buffer over MgCl(2) solutions since it maximised pDNA yield (96.2±4.9%) and protein removal (61.3±3.0%), while providing for a substantial removal of RNA (65.5±3.5%) and gDNA (44.7±14.1%). Although the use of pH 3.5 maximised removal of impurities (~75%), the best compromise between plasmid yield (~96%) and RNA clearance (~60-70%) was obtained for a pH of 5.2. Plasmid yield was maximal (>96%) when the concentration of acetate and potassium ions in the incoming lysate feed were 1.7 M and 1.0 M, respectively. The pre-treatment of lysates with RNase A deteriorated the performance since the resulting oligoribonucleotides lack the cis-diol group at their 3' termini. Overall, the results support the idea that charge transfer interactions between the boron atom at acidic pH and electron donor groups in the aromatic bases of nucleic acids and side residues of proteins are responsible for the non-specific removal of gDNA, RNA and proteins. PMID:22024344

  1. DEMONSTRATION BULLETIN: IN SITU ELECTROKINETIC EXTRACTION SYSTEM - SANDIA NATIONAL LABORATORIES

    EPA Science Inventory

    Sandia National Laboratories (SNL) has developed an in situ soil remediation system that uses electrokinetic principles to remediate hexavalent chromium-contaminated unsaturated or partially saturated soils. The technology involves the in situ application of direct current to the...

  2. Theoretical evaluation of a technique for electrokinetic decontamination of soils

    NASA Astrophysics Data System (ADS)

    Yu, Ji-Wei; Neretnieks, Ivars

    1997-04-01

    An electrokinetic decontamination process has been modeled to investigate the feasibility of using electrokinetic soil remediation technology to remove 137Cs and 90Sr from the soil. 100 V DC current is applied to a 3-meter-long soil column by electrodes connected to the soil. The prediction results have shown that the efficiency of the electrokinetic treatment depends on the sorption and diffusion parameters. High sorption and slow diffusion will demand long treatment time. If the soil to be treated has similar sorption and diffusion properties as bentonite, and when the soil is flushed with saline water that leads to less sorption, both 137Cs and 90Sr may be cleaned by the electrokinetic process within a few months.

  3. Enhanced electrokinetic dissolution of naphthalene and 2,4-DNT from contaminated soils.

    PubMed

    Jiradecha, Chatdanai; Urgun-Demirtas, Meltem; Pagilla, Krishna

    2006-08-10

    Electrokinetic soil remediation has been proven to remove heavy metals and polar organics from low hydraulic conductivity subsurface environment. In this study, carboxymethyl-beta-cyclodextrin (CMCD) was used as a carrier to assist electrokinetic treatment for removal of low polarity organic contaminants from soils (2.2% organic carbon content). Naphthalene and 2,4-dinitrotoluene (2,4-DNT) were selected as the test compounds. The results from columns experiments showed that 46 and 43% of naphthalene and 2,4-DNT, respectively, were removed using 0.01 N NaNO(3) flushing solution with 40 V electrical potential while 70 and 72% of naphthalene and 2,4-DNT were removed using 2 g/L CMCD solution. Naphthalene and 2,4-DNT removal was enhanced to 83 and 89%, respectively, by using 2 g/L CMCD with 40 V electrical potential. Findings from this study also demonstrated that cyclodextrin assisted electrokinetics can enhance the removal rate of naphthalene and 2,4-DNT. Electric potential applied has more influence on the contaminant removal than the amount of CMCD used. Higher voltage application caused increase in the removal rate of naphthalene and 2,4-DNT, and appeared to be one of the critical factors in obtaining higher contaminant removal while increasing CMCD solution concentration above 2 g/L appeared to have little effect on the contaminant removal. PMID:16359784

  4. Selective Label-free Electrokinetic Cell Tracker (SELECT): a novel liquid platform for cell characterization

    NASA Astrophysics Data System (ADS)

    Taruvai Kalyana Kumar, Rajeshwari; de Mello Gindri, Izabelle; Kinnamon, David; Kanchustambham, Pradyotha; Rodrigues, Danieli; Prasad, Shalini; BiomaterialsOsseointegration; Novel Engineering Lab Collaboration

    2015-03-01

    Characterization and analysis of rare cells provide critical cues for early diagnosis of diseases. Electrokinetic cell separation has been previously established to have greater efficiency when compared to traditional flow cytometry methods. It has been shown by many researchers that buffer solutions in which cells are suspended in, have enormous effects on producing required dielectrophoretic (DEP) forces to characterize cells. Most commonly used suspension buffers used are deionized water and cell media. However, these solutions exhibit high level of intrinsic noise, which greatly masks the electrokinetic signals from cells under study. Ionic liquids (ILs) show promise towards the creation of conductive fluids with required electrical properties. The goal of this project is to design and test ILs for enhancing DEP forces on cells while creating an environment for preserving their integrity. We analyzed two methylimidazolium based ILs as suspension medium for cell separation. These dicationic ILs possess slight electrical and structural differences with high thermal stability. The two ILs were tested for cytotoxicity using HeLa and bone cells. The effects of electrical neutrality, free charge screening due to ILs towards enhanced electrokinetic signals from cells were studied with improved system resolution and no harmful effects.

  5. Gas chromatographic separation of hydrogen isotopes using metal hydrides

    SciTech Connect

    Aldridge, F.T.

    1984-05-09

    A study was made of the properties of metal hydrides which may be suitable for use in chromatographic separation of hydrogen isotopes. Sixty-five alloys were measured, with the best having a hydrogen-deuterium separation factor of 1.35 at 60/sup 0/C. Chromatographic columns using these alloys produced deuterium enrichments of up to 3.6 in a single pass, using natural abundance hydrogen as starting material. 25 references, 16 figures, 4 tables.

  6. Electrokinetics dependence on water-content in sand

    NASA Astrophysics Data System (ADS)

    Allègre, V.; Lehmann, F.; Jouniaux, L.; Sailhac, P.; Matthey, P.

    2009-12-01

    The electrokinetic potential results from the coupling between the water flow and the electrical current because of the presence of ions within water. This coupling is well described in fluid-saturated media, however its behavior under unsaturated flow conditions is still discussed. We propose here an experimental approach which can clearly describe streaming potential variations in unsaturated conditions. Several drainage experiments have been performed within a column filled with a clean sand. Streaming potential measurements are combined to capillary pressure and to water content measurements each 10 centimeter along the column. In order to model hydrodymanics during each experiment, we solve Richards equation in an inverse way which allows us to establish the relation between hydraulic conductivity and water content, and retention relation. The electrokinetic coefficient C shows a more complex behavior than it was previously reported and can not be fitted by the existing models. We show that the normalized electrokinetic coefficient increases first when water saturation decreases from 100% to about 80% - 95%, and then decreases as the water saturation decreases, whereas all previous works described a unifrom decrease of the normalized electrokinetic coefficient as water saturation decreases. We delimited two water saturation domains, and deduced two different empirical laws describing the evolution of the electrokinetic coefficient in unsaturated conditions. Finally, electrical potentials data from four different drainage experiments and hydrodynamics were jointly inversed, including electrical conductivity measurements in order to find a robust description of the electrokinetic coefficient behavior in unsaturated conditions.

  7. Microbial fuel cell driving electrokinetic remediation of toxic metal contaminated soils.

    PubMed

    Habibul, Nuzahat; Hu, Yi; Sheng, Guo-Ping

    2016-11-15

    An investigation of the feasibility of in-situ electrokinetic remediation for toxic metal contaminated soil driven by microbial fuel cell (MFC) is presented. Results revealed that the weak electricity generated from MFC could power the electrokinetic remediation effectively. The metal removal efficiency and its influence on soil physiological properties were also investigated. With the electricity generated through the oxidation of organics in soils by microorganisms, the metals in the soils would mitigate from the anode to the cathode. The concentrations of Cd and Pb in the soils increased gradually through the anode to the cathode regions after remediation. After about 143days and 108 days' operation, the removal efficiencies of 31.0% and 44.1% for Cd and Pb at the anode region could be achieved, respectively. Soil properties such as pH and soil conductivity were also significantly redistributed from the anode to the cathode regions. The study shows that the MFC driving electrokinetic remediation technology is cost-effective and environmental friendly, with a promising application in soil remediation. PMID:27388419

  8. Uncertainty Quantification of Nonlinear Electrokinetic Response in a Microchannel-Membrane Junction

    NASA Astrophysics Data System (ADS)

    Alizadeh, Shima; Iaccarino, Gianluca; Mani, Ali

    2015-11-01

    We have conducted uncertainty quantification (UQ) for electrokinetic transport of ionic species through a hybrid microfluidic system using different probabilistic techniques. The system of interest is an H-configuration consisting of two parallel microchannels that are connected via a nafion junction. This system is commonly used for ion preconcentration and stacking by utilizing a nonlinear response at the channel-nafion junction that leads to deionization shocks. In this work, the nafion medium is modeled as many parallel nano-pores where, the nano-pore diameter, nafion porosity, and surface charge density are independent random variables. We evaluated the resulting uncertainty on the ion concentration fields as well as the deionization shock location. The UQ methods predicted consistent statistics for the outputs and the results revealed that the shock location is weakly sensitive to the nano-pore surface charge and primarily driven by nano-pore diameters. The present study can inform the design of electrokinetic networks with increased robustness to natural manufacturing variability. Applications include water desalination and lab-on-a-chip systems. Shima is a graduate student in the department of Mechanical Engineering at Stanford University. She received her Master's degree from Stanford in 2011. Her research interests include Electrokinetics in porous structures and high performance computing.

  9. Remediation of phthalates in river sediment by integrated enhanced bioremediation and electrokinetic process.

    PubMed

    Yang, Gordon C C; Huang, Sheng-Chih; Jen, Yu-Sheng; Tsai, Pei-Shin

    2016-05-01

    The objective of this study was to evaluate the feasibility of enhanced bioremediation coupling with electrokinetic process for promoting the growth of intrinsic microorganisms and removing phthalate esters (PAEs) from river sediment by adding an oxygen releasing compound (ORC). Test results are given as follows: Enhanced removal of PAEs was obtained by electrokinetics, through which the electroosmotic flow would render desorption of organic pollutants from sediment particles yielding an increased bioavailability. It was also found that the ORC injected into the sediment compartment not only would alleviate the pH value variation due to acid front and base front, but would be directly utilized as the carbon source and oxygen source for microbial growth resulting in an enhanced degradation of organic pollutants. However, injection of the ORC into the anode compartment could yield a lower degree of microbial growth due to the loss of ORC during the transport by EK. Through the analysis of molecular biotechnology it was found that both addition of an ORC and application of an external electric field can be beneficial to the growth of intrinsic microbial and abundance of microflora. In addition, the sequencing result showed that PAEs could be degraded by the following four strains: Flavobacterium sp., Bacillus sp., Pseudomonas sp., and Rhodococcus sp. The above findings confirm that coupling of enhanced bioremediation and electrokinetic process could be a viable remediation technology to treat PAEs-contaminated river sediment. PMID:26733014

  10. Determination of trace anions in liquefied petroleum gas using liquid absorption and electrokinetic migration for enrichment followed by ion chromatography.

    PubMed

    Li, Meilan; Yang, Jianmin; Li, Hai-Fang; Lin, Jin-Ming

    2012-06-01

    A simple sample enrichment technique, electrokinetic migration enrichment in single phase using a designed device, coupled with ion chromatography is presented for the determination of four anions (H(2)PO(4)(-), Cl(-), NO(3)(-), and SO(4)(2-)) in liquefied petroleum gas by liquid adsorption. The electrokinetic migration enrichment is based on the phenomenon of ion electrokinetic migration to the opposite electrode. When the anions migrated to the anode in a smaller volume chamber under the electric field, the concentration was realized. The main parameters affecting enrichment efficiency of applied voltage and enrichment time were investigated. The ion chromatography condition for anions separation was also studied. Under the optimal electrokinetic migration enrichment and ion chromatography conditions, the four anions were detected simultaneously with good linear relationship (r(2) = 0.9908-0.9968) and high precisions (less than 5% of the relative standard deviations of peak areas). The limits of detection of anions (S/N of 3) were in the range of 8-600 μg L(-1). The enrichment factors of the four anions ranged from 3.1 to 5.8. The established method was successfully applied to the analysis of the trace anions in liquefied petroleum gas by liquid adsorption with satisfactory results. The advantages of this method are simple operation and low cost.

  11. Method and apparatus for electrokinetic transport

    NASA Technical Reports Server (NTRS)

    James, Patrick Ismail (Inventor); Stejic, George (Inventor)

    2012-01-01

    Controlled electrokinetic transport of constituents of liquid media can be achieved by connecting at least two volumes containing liquid media with at least one dielectric medium with opposing dielectric surfaces in direct contact with said liquid media, and establishing at least one conduit across said dielectric medium, with a conduit inner surface surrounding a conduit volume and at least a first opening and a second opening opposite to the first opening. The conduit is arranged to connect two volumes containing liquid media and includes a set of at least three electrodes positioned in proximity of the inner conduit surface. A power supply is arranged to deliver energy to the electrodes such that time-varying potentials inside the conduit volume are established, where the superposition of said potentials represents at least one controllable traveling potential well that can travel between the opposing conduit openings.

  12. Enhancement of electrokinetic decontamination with EDTA.

    PubMed

    Karim, M A; Khan, L I

    2012-01-01

    The effect of ethylenediaminetetraacetic acid (EDTA) during electrokinetic decontamination (EKD) was investigated in this research. EDTA is a ligand that can form soluble complexes with precipitated heavy metals inside soil pores. Millpond sludge, primarily contaminated with lead (Pb) and zinc (Zn), was subjected to EKD with and without the presence of EDTA. Dilute EDTA solutions with strengths of 0.05 M and 0.125 M were injected into the millpond sludge by electroosmosis. Several beneficial effects of using EDTA were observed in this research. One was that the presence of EDTA substantially increased the electroosmotic (EO) flow in the millpond sludge indicating that it could significantly reduce the duration of EKD. Another advantage was that a significantly higher percentage of Pb and Zn removal was achieved from the solid phase due to the complexation of EDTA with these heavy metals. Also, EDTA was able to prevent the precipitation of metals at the cathode electrode, typically observed in EKD process. PMID:23393970

  13. Comparative studies of peak intensities and chromatographic separation of proteolytic digests, PTMs, and intact proteins obtained by nanoLC-ESI MS analysis at room and elevated temperatures.

    PubMed

    Moskovets, Eugene V; Ivanov, Alexander R

    2016-06-01

    This work demonstrates that the chromatographic separation performed at highly stabilized elevated temperature results in significant improvements in sensitivity, quantitative accuracy, chromatographic resolution, and run-to-run reproducibility of nanoLC-MS analysis of complex peptides mixtures. A newly developed platform was shown to provide conditions for accurate temperature stabilization and temperature homogeneity when performing nanoLC-ESI MS analysis. We quantitatively assessed and compared the recovery of peptides and small proteins from nanoLC columns at room and elevated temperatures. We found that analyses performed at highly stabilized elevated temperatures led to improved detection sensitivity, reproducibility, and chromatographic resolution in reversed-phase LC separation of unmodified peptides (both hydrophilic and hydrophobic), post-translationally modified peptides (O-phosphorylated), and small intact proteins. The analytical benefits of elevated temperatures for qualitative and quantitative proteomic LC-MS profiling were demonstrated using mixtures of synthetic peptides, tryptic digests of mixtures of model proteins, and digested total lysates of isolated rat kidney mitochondria. The effect of elevated temperature on the ion suppression was also demonstrated. Graphical Abstract A fragment of overlaid LC retention time-m/z planar views demonstrates the improved separation performance in the analysis of a complex peptide mixture at elevated temperature. Retention time-m/z 2D peptide features detected at 60 °C (magenta) were matched and aligned with features detected at room temperature (green).

  14. Geochemical assessment of metal transport in glacial till during electrokinetic remediation.

    PubMed

    Al-Hamdan, Ashraf Z; Reddy, Krishna R

    2008-04-01

    This paper presents the chemical speciation and retention behavior of chromium (Cr), nickel (Ni), and cadmium (Cd) prior to and after the electrokinetic remediation in glacial till soil. The speciation of the metals was predicted using the chemical speciation program MINEQL(+). The simulations were performed for single-contaminant with only Cr(VI) or Ni, and multi-contaminants consisting of: (1) Cr(VI), Ni, and Cd; (2) Cr(III), Ni and Cd; (3) Cr(VI), Cr(III), Ni and Cd; (4) Cr(VI), Ni, and Cd with reducing agents; and (5) Cr(III), Ni, and Cd with oxidizing agent (Mn). The results showed that the speciation and distribution of cationic metals [Ni, Cd, and Cr(III)] in glacial till soil remain unaffected or slightly affected during electrokinetics. This is attributed to the high pH buffering capacity of the glacial till, leading the metals to precipitate in the soil prior to and after electrokinetics. This study showed that during electrokinetics, Cr(VI) existed as anionic complex and migrated towards the anode and the migration is maximum in case of a single-contaminant system. The study also showed that near the anode in the absence of any reducing and oxidizing agent, Cr(VI) mostly adsorbed, and some of Cr(VI) reduced to Cr(III) and migrated towards the cathode and finally precipitated due to high pH conditions. Ni and Cd remain adsorbed or precipitated due to the high pH conditions throughout the soil. Among the reducing agents, the sulfide had significant effect on the migration of metals compared to ferrous ions. While in the presence of oxidizing agent (Mn), no noticeable Cr(VI) was found in the soil sample indicating the reduction of Cr(VI) to Cr(III) and the predominance of reducing conditions due to the presence of naturally occurring iron in the glacial till soil. Overall, this study provides a reasonable explanation of the speciation and distribution of chromium, nickel and cadmium during the electrokinetic remediation of glacial till soil.

  15. Acquisition of a Gas Chromatograph/Mass Spectrometer System for Laboratory Study of Prebiotic Organic Geochemical Processes on the Early Earth, Mars, and Meteorites

    NASA Technical Reports Server (NTRS)

    McCollom, Thomas

    2004-01-01

    This was a major equipment grant that provided funds ($72K) for purchase of a benchtop gas chromatograph-mass spectrometer (GC-MS) for use in experimental studies of prebiotic organic compounds. An Agilent model 689015973 GC-MS was purchased and installed in the PI's lab in August of 2003. The instrument is now being used for a variety of research projects. The primary use of the instrument is to analyze and quantify organic products of laboratory experiments conducted by the PI. One example is shown, which shows organic products (predominantly n-alkanes) formed during Fischer-Tropsch-type abiotic synthesis under hydrothermal conditions. The analytical capabilities of the GC- MS allowed identification of the numerous organic products of this as well as other laboratory experiments. A key use of the instrument in this research is that the mass spectrometer capabilities allow use of isotopically labeled reactants to trace the progress of reactions and evaluate background contaminants. collaborative projects with other scientists involved in exobiology & astrobiology research (e.g., Mitch Schulte, NASA Ames; Katrina Edwards, Woods Hole Oceanographic Institution). For instance, an analysis of membrane lipids of an lithoautotrophic iron-oxidizing bacteria being grown on basalt as a source of metabolic energy, a project where the instrument is being used to evaluate possible biomarker compounds from these organisms is shown. These iron oxidizers are thought to be similar to those living within the ocean crust, and are being investigated as possible analog organisms to those on the early Earth or crust of Mars. The instrument has also been used by an outside investigator (graduate student Brandon Canfeld, Arizona State University) for identification and isotopic characterization of experimental products of abiotic organic synthesis experiments he is conducting with Dr. John Holloway. analysis of quality control samples for other NASA-funded projects. For instance, an

  16. On the capabilities of nano electrokinetic thrusters for space propulsion

    NASA Astrophysics Data System (ADS)

    Diez, F. J.; Hernaiz, G.; Miranda, J. J.; Sureda, M.

    2013-02-01

    A theoretical analysis considering the capabilities of nano electrokinetic thrusters for space propulsion is presented. The work describes an electro-hydro-dynamic model of the electrokinetic flow in nano-channels and represents the first attempt to exploit the advantages of the electrokinetic effect as the basis for a new class of nano-scale thrusters suitable for space propulsion. Among such advantages are their small volume, fundamental simplicity, overall low mass, and actuation efficiency. Their electrokinetic efficiency is affected by the slip length, surface charge, pH and molarity. These design variables are analyzed and optimized for the highest electrokinetic performance inside nano-channels. The optimization is done for power consumption, thrust and specific impulse resulting in high theoretical efficiency ˜99% with corresponding high thrust-to-power ratios. Performance curves are obtained for the electrokinetic design variables showing that high molarity electrolytes lead to high thrust and specific impulse values, whereas low molarities provide highest thrust-to-power ratios and efficiencies. A theoretically designed 100 nm wide by 1 μm long emitter optimized using the ideal performance charts developed would deliver thrusts from 5 to 43 μN, specific impulse from 60 to 210 s, and would have power consumption between 1-15 mW. It should be noted that although this is a detail analytical analysis no prototypes exist and any future experimental work will face challenges that could affect the final performance. By designing an array composed of thousands of these single electrokinetic emitters, it would result in a flexible and scalable propulsion system capable of providing a wide range of thrust control for different mission scenarios and maintaining very high efficiencies and thrust-to-power ratio by varying the number of emitters in use at any one time.

  17. Electrokinetic demonstration at the unlined chromic acid pit

    SciTech Connect

    Lindgren, E.R.; Hankins, M.G.; Mattson, E.D.; Duda, P.M.

    1998-01-01

    Heavy-metal contaminated soils are a common problem at Department of Energy (DOE)-operated sites and privately owned facilities throughout the nation. One emerging technology which can remove heavy metals from soil in situ is electrokinetics. To conduct electrokinetic (EK) remediation, electrodes are implanted into the ground, and a direct current is imposed between the electrodes. Metal ions dissolved in the soil pore water migrate towards an electrode where they can be removed. The electrokinetic program at Sandia National Laboratories (SNL) has been focusing on electrokinetic remediation for unsaturated soils. A patent was awarded for an electrokinetic electrode system designed at SNL for applications to unsaturated soils. Current research described in this report details an electrokinetic remediation field demonstration of a chromium plume that resides in unsaturated soil beneath the SNL Chemical Waste Landfill (CWL). This report describes the processes, site investigation, operation and monitoring equipment, testing procedures, and extraction results of the electrokinetic demonstration. This demonstration successfully removed chromium contamination in the form of chromium(VI) from unsaturated soil at the field scale. After 2700 hours of operation, 600 grams of Cr(VI) was extracted from the soil beneath the SNL CWL in a series of thirteen tests. The contaminant was removed from soil which has moisture contents ranging from 2 to 12 weight percent. This demonstration was the first EK field trial to successfully remove contaminant ions from and soil at the field scale. Although the new patented electrode system was successful in removing an anionic contaminant (i.e., chromate) from unsaturated sandy soil, the electrode system was a prototype and has not been specifically engineered for commercialization. A redesign of the electrode system as indicated by the results of this research is suggested for future EK field trials.

  18. Ask the experts: chromatographic baselines.

    PubMed

    Smith, Graeme; James, Christopher A; Scott, Rebecca; Woolf, Eric

    2014-05-01

    Bioanalysis invited a selection of leading researchers to express their views on chromatographic baseline assignment in the bioanalytical laboratory. The topics discussed include the challenges presented with ensuring automated baseline assignment is correct, when reintegration is necessary, regulation and consistency in terminology. Their enlightening responses provide a valuable insight into developing an industry consensus towards reintegration. An accompanying commentary article in this issue, authored by Howard Hill and colleagues (Huntingdon Life Sciences), provides background to this much debated topic.

  19. A simple novel device for air sampling by electrokinetic capture

    SciTech Connect

    Gordon, Julian; Gandhi, Prasanthi; Shekhawat, Gajendra; Frazier, Angel; Hampton-Marcell, Jarrad; Gilbert, Jack A.

    2015-12-27

    A variety of different sampling devices are currently available to acquire air samples for the study of the microbiome of the air. All have a degree of technical complexity that limits deployment. Here, we evaluate the use of a novel device, which has no technical complexity and is easily deployable. An air-cleaning device powered by electrokinetic propulsion has been adapted to provide a universal method for collecting samples of the aerobiome. Plasma-induced charge in aerosol particles causes propulsion to and capture on a counter-electrode. The flow of ions creates net bulk airflow, with no moving parts. A device and electrode assembly have been re-designed from air-cleaning technology to provide an average air flow of 120 lpm. This compares favorably with current air sampling devices based on physical air pumping. Capture efficiency was determined by comparison with a 0.4 μm polycarbonate reference filter, using fluorescent latex particles in a controlled environment chamber. Performance was compared with the same reference filter method in field studies in three different environments. For 23 common fungal species by quantitative polymerase chain reaction (qPCR), there was 100 % sensitivity and apparent specificity of 87%, with the reference filter taken as “gold standard.” Further, bacterial analysis of 16S RNA by amplicon sequencing showed equivalent community structure captured by the electrokinetic device and the reference filter. Unlike other current air sampling methods, capture of particles is determined by charge and so is not controlled by particle mass. We analyzed particle sizes captured from air, without regard to specific analyte by atomic force microscopy: particles at least as low as 100 nM could be captured from ambient air. This work introduces a very simple plug-and-play device that can sample air at a high-volume flow rate with no moving parts and collect particles down to the sub-micron range. In conclusion, the performance of the

  20. A simple novel device for air sampling by electrokinetic capture

    DOE PAGESBeta

    Gordon, Julian; Gandhi, Prasanthi; Shekhawat, Gajendra; Frazier, Angel; Hampton-Marcell, Jarrad; Gilbert, Jack A.

    2015-12-27

    A variety of different sampling devices are currently available to acquire air samples for the study of the microbiome of the air. All have a degree of technical complexity that limits deployment. Here, we evaluate the use of a novel device, which has no technical complexity and is easily deployable. An air-cleaning device powered by electrokinetic propulsion has been adapted to provide a universal method for collecting samples of the aerobiome. Plasma-induced charge in aerosol particles causes propulsion to and capture on a counter-electrode. The flow of ions creates net bulk airflow, with no moving parts. A device and electrodemore » assembly have been re-designed from air-cleaning technology to provide an average air flow of 120 lpm. This compares favorably with current air sampling devices based on physical air pumping. Capture efficiency was determined by comparison with a 0.4 μm polycarbonate reference filter, using fluorescent latex particles in a controlled environment chamber. Performance was compared with the same reference filter method in field studies in three different environments. For 23 common fungal species by quantitative polymerase chain reaction (qPCR), there was 100 % sensitivity and apparent specificity of 87%, with the reference filter taken as “gold standard.” Further, bacterial analysis of 16S RNA by amplicon sequencing showed equivalent community structure captured by the electrokinetic device and the reference filter. Unlike other current air sampling methods, capture of particles is determined by charge and so is not controlled by particle mass. We analyzed particle sizes captured from air, without regard to specific analyte by atomic force microscopy: particles at least as low as 100 nM could be captured from ambient air. This work introduces a very simple plug-and-play device that can sample air at a high-volume flow rate with no moving parts and collect particles down to the sub-micron range. In conclusion, the performance of

  1. Gas chromatographic methods for determination of gamma-BHC in technical emulsifiable concentrates and water-dispersible powder formulations and in lindane shampoo and lotion: collaborative study.

    PubMed

    Miles, J W; Mount, D L; Beckmann, T J; Carrigan, S K; Galoux, I M; Hitos, P; Hodge, M C; Kissler, K; Martijn, A; Sanchez-Rasero, F

    1984-01-01

    Although the gas chromatographic separation of the isomers of BHC was demonstrated two decades ago, the present AOAC method of analysis of BHC for gamma-isomer (lindane) content is based on a separation carried out on a liquid chromatographic partition column. A method of analysis has been developed that uses an OV-210 column for separation of the gamma-isomer from the other isomers and impurities in technical BHC. Di-n-propyl phthalate was chosen as an internal standard. The same system allows quantitation of lindane in lotion and shampoo after these products are extracted with ethyl acetate-isooctane (1 + 4). The analytical methods were subjected to a collaborative trial with 10 laboratories. The coefficient of variation for technical BHC was 2.83%. For the water-dispersible powder and emulsifiable concentrate, the coefficients of variation were 2.89% and 4.62%, respectively. Coefficients of variation for 1% lindane lotion and shampoo were 4.36% and 11.92%, respectively. The method has been adopted official first action.

  2. Importance of MS selectivity and chromatographic separation in LC-MS/MS-based methods when investigating pharmaceutical metabolites in water. Dipyrone as a case of study.

    PubMed

    Ibáñez, M; Gracia-Lor, E; Sancho, J V; Hernández, F

    2012-08-01

    Pharmaceuticals are emerging contaminants of increasing concern because of their presence in the aquatic environment and potential to reach drinking-water sources. After human and/or veterinary consumption, pharmaceuticals can be excreted in unchanged form, as the parent compound, and/or as free or conjugated metabolites. Determination of most pharmaceuticals and metabolites in the environment is commonly made by liquid chromatography (LC) coupled to mass spectrometry (MS). LC coupled to tandem MS is the technique of choice nowadays in this field. The acquisition of two selected reaction monitoring (SRM) transitions together with the retention time is the most widely accepted criterion for a safe quantification and confirmation assay. However, scarce attention is normally paid to the selectivity of the selected transitions as well as to the chromatographic separation. In this work, the importance of full spectrum acquisition high-resolution MS data using a hybrid quadrupole time-of-flight analyser and/or a suitable chromatographic separation (to reduce the possibility of co-eluting interferences) is highlighted when investigating pharmaceutical metabolites that share common fragment ions. For this purpose, the analytical challenge associated to the determination of metabolites of the widely used analgesic dipyrone (also known as metamizol) in urban wastewater is discussed. Examples are given on the possibilities of reporting false positives of dypirone metabolites by LC-MS/MS under SRM mode due to a wrong assignment of identity of the compounds detected. PMID:22899513

  3. Transport of radioactive ions in soil by electrokinetics

    SciTech Connect

    Buehler, M.F.; Surma, J.E.; Virden, J.W.

    1994-10-01

    An electrokinetic approach is being evaluated for in situ soil remediation at the Hanford Site in Richland, Washington. This approach uses an applied electric field to induce transport of both radioactive and hazardous waste ions in soil. The work discussed in this paper involves the development of a new method to monitor the movement of the radioactive ions within the soil during the electrokinetic process. A closed cell and a gamma counter were used to provide iii situ measurements of {sup 137}Cs and {sup 60}Co movement in Hanford soil. Preliminary results show that for an applied potential of 200 V over approximately 200 hr, {sup 137}Cs and {sup 60}60 were transported a distance of 4 to 5 in. The monitoring technique demonstrated the feasibility of using electrokinetics for soil separation applications.

  4. Reducing spurious flow in simulations of electrokinetic phenomena

    NASA Astrophysics Data System (ADS)

    Rempfer, Georg; Davies, Gary B.; Holm, Christian; de Graaf, Joost

    2016-07-01

    Electrokinetic transport phenomena can strongly influence the behaviour of macromolecules and colloidal particles in solution, with applications in, e.g., DNA translocation through nanopores, electro-osmotic flow in nanocapillaries, and electrophoresis of charged macromolecules. Numerical simulations are an important tool to investigate these electrokinetic phenomena, but are often plagued by spurious fluxes and spurious flows that can easily exceed physical fluxes and flows. Here, we present a method that reduces one of these spurious currents, spurious flow, by several orders of magnitude. We demonstrate the effectiveness and generality of our method for both the electrokinetic lattice-Boltzmann and finite-element-method based algorithms by simulating a charged sphere in an electrolyte solution and flow through a nanopore. We also show that previous attempts to suppress these spurious currents introduce other sources of error.

  5. Method for eliminating gas blocking in electrokinetic pumping systems

    DOEpatents

    Arnold, Don W.; Paul, Phillip H.; Schoeniger, Joseph S.

    2001-09-11

    A method for eliminating gas bubble blockage of current flow during operation of an electrokinetic pump. By making use of the ability to modify the surface charge on the porous dielectric medium used in electrokinetic pumps, it becomes possible to place electrodes away from the pressurized region of the electrokinetic pump. While gas is still generated at the electrodes they are situated such that the generated gas can escape into a larger buffer reservoir and not into the high pressure region of the pump where the gas bubbles can interrupt current flow. Various combinations of porous dielectric materials and ionic conductors can be used to create pumps that have desirable electrical, material handling, and flow attributes.

  6. Modeling of mesoscopic electrokinetic phenomena using charged dissipative particle dynamics

    NASA Astrophysics Data System (ADS)

    Deng, Mingge; Li, Zhen; Karniadakis, George

    2015-11-01

    In this work, we propose a charged dissipative particle dynamics (cDPD) model for investigation of mesoscopic electrokinetic phenomena. In particular, this particle-based method was designed to simulate micro- or nano- flows which governing by Poisson-Nernst-Planck (PNP) equation coupled with Navier-Stokes (NS) equation. For cDPD simulations of wall-bounded fluid systems, a methodology for imposing correct Dirichlet and Neumann boundary conditions for both PNP and NS equations is developed. To validate the present cDPD model and the corresponding boundary method, we perform cDPD simulations of electrostatic double layer (EDL) in the vicinity of a charged wall, and the results show good agreement with the mean-field theoretical solutions. The capacity density of a parallel plate capacitor in salt solution is also investigated with different salt concentration. Moreover, we utilize the proposed methodology to study the electroosmotic and electroosmotic/pressure-driven flow in a micro-channel. In the last, we simulate the dilute polyelectrolyte solution both in bulk and micro-channel, which show the flexibility and capability of this method in studying complex fluids. This work was sponsored by the Collaboratory on Mathematics for Mesoscopic Modeling of Materials (CM4) supported by DOE.

  7. Scale-up on electrokinetic remediation: Engineering and technological parameters.

    PubMed

    López-Vizcaíno, Rubén; Navarro, Vicente; León, María J; Risco, Carolina; Rodrigo, Manuel A; Sáez, Cristina; Cañizares, Pablo

    2016-09-01

    This study analyses the effect of the scale-up of electrokinetic remediation (EKR) processes in natural soils. A procedure is proposed to prepare soils based on a compacting process to obtaining soils with similar moisture content and density to those found in real soils in the field. The soil used here was from a region with a high agrarian activity (Mora, Spain). The scale-up study was performed in two installations at different scales: a mock-up pilot scale (0.175m(3)) and a prototype with a scale that was very similar to a real application (16m(3)). The electrode configuration selected consisted of rows of graphite electrodes facing each other located in electrolyte wells. The discharge of 20mg of 2,4-dichlorophenoxyacetic acid [2,4-D] per kg of dry soil was treated by applying an electric potential gradient of 1Vcm(-1). An increase in scale was observed to directly influence the amount of energy supplied to the soil being treated. As a result, electroosmotic and electromigration flows and electric heating are more intense than in smaller-scale tests (24%, 1% and 25%, respectively respect to the values in prototype). In addition, possible leaks were evaluated by conducting a watertightness test and quantifying evaporation losses.

  8. The influence of soft layer electrokinetics on bacterial electroporation

    NASA Astrophysics Data System (ADS)

    Moran, Jeffrey; Dingari, Naga Neehar; Buie, Cullen

    2015-11-01

    Electroporation of mammalian cells has received a significant amount of theoretical attention over the last decade because of its ability to deliver biologically active molecules into cells using short and strong electric field pulses. However, application of the same theory to bacterial electroporation presents significant challenges because of the presence of charged soft layers around bacteria. The soft layer charge distribution has been found to significantly influence bacterial electrophoretic mobility and polarizability because it alters the electric potential spatial distribution around the cell envelope. In addition, the RC charging time scale of both the soft layer and electric double layer is of the order of microseconds, which is also of similar order of magnitude as the pore creation time scale. Therefore in this study, we investigate the influence of soft layer electrokinetics on the spatial pore distribution and the temporal pore radius evolution during bacteria electroporation, which are quantitative measures of a bacterium's amenability to electroporation. The study will have significant impact on designing and optimizing bacteria electroporation platforms for gene and drug delivery applications.

  9. Scale-up on electrokinetic remediation: Engineering and technological parameters.

    PubMed

    López-Vizcaíno, Rubén; Navarro, Vicente; León, María J; Risco, Carolina; Rodrigo, Manuel A; Sáez, Cristina; Cañizares, Pablo

    2016-09-01

    This study analyses the effect of the scale-up of electrokinetic remediation (EKR) processes in natural soils. A procedure is proposed to prepare soils based on a compacting process to obtaining soils with similar moisture content and density to those found in real soils in the field. The soil used here was from a region with a high agrarian activity (Mora, Spain). The scale-up study was performed in two installations at different scales: a mock-up pilot scale (0.175m(3)) and a prototype with a scale that was very similar to a real application (16m(3)). The electrode configuration selected consisted of rows of graphite electrodes facing each other located in electrolyte wells. The discharge of 20mg of 2,4-dichlorophenoxyacetic acid [2,4-D] per kg of dry soil was treated by applying an electric potential gradient of 1Vcm(-1). An increase in scale was observed to directly influence the amount of energy supplied to the soil being treated. As a result, electroosmotic and electromigration flows and electric heating are more intense than in smaller-scale tests (24%, 1% and 25%, respectively respect to the values in prototype). In addition, possible leaks were evaluated by conducting a watertightness test and quantifying evaporation losses. PMID:27209275

  10. Evaluation of the suitability of chromatographic systems to predict human skin permeation of neutral compounds.

    PubMed

    Hidalgo-Rodríguez, Marta; Soriano-Meseguer, Sara; Fuguet, Elisabet; Ràfols, Clara; Rosés, Martí

    2013-12-18

    Several chromatographic systems (three systems of high-performance liquid chromatography and two micellar electrokinetic chromatography systems) besides the reference octanol-water partition system are evaluated by a systematic procedure previously proposed in order to know their ability to model human skin permeation. The precision achieved when skin-water permeability coefficients are correlated against chromatographic retention factors is predicted within the framework of the solvation parameter model. It consists in estimating the contribution of error due to the biological and chromatographic data, as well as the error coming from the dissimilarity between the human skin permeation and the chromatographic systems. Both predictions and experimental tests show that all correlations are greatly affected by the considerable uncertainty of the skin permeability data and the error associated to the dissimilarity between the systems. Correlations with much better predictive abilities are achieved when the volume of the solute is used as additional variable, which illustrates the main roles of both lipophilicity and size of the solute to penetrate through the skin. In this way, the considered systems are able to give precise estimations of human skin permeability coefficients. In particular, the HPLC systems with common C18 columns provide the best performances in emulating the permeation of neutral compounds from aqueous solution through the human skin. As a result, a methodology based on easy, fast, and economical HPLC measurements in a common C18 column has been developed. After a validation based on training and test sets, the method has been applied with good results to the estimation of skin permeation of several hormones and pesticides.

  11. Chromatographic behaviors of proteins on cation-exchange column.

    PubMed

    Li, Rong; Chen, Guo-Liang; Zhao, Wen-Ming

    2004-12-01

    A weak cation-exchanger (XIDACE-WCX) has been synthesized by the indirect method. The chromatographic characteristics of the synthesized packing was studied in detail. The standard protein mixture and lysozyme from egg white were separated with the prepared chromatographic column. The chromatographic thermodynamics of proteins was studied in a wide temperature range. Thermodynamic parameters standard enthalpy change (deltaH0) and standard entropy change (deltaS0) and compensation temperature (beta) at protein denaturation were determined in the chromatographic system. By using obtained deltaS0, the conformational change of proteins was judged in the chromatographic process. The linear relationship between deltaH0 and deltaS0 can be used to identify the identity of the protein retention mechanism in the weak cation-exchange chromatography. The interaction between weak cation-exchanger and metal ions was investigated. Several metal chelate columns were prepared. The effects of introducing metal ion into the naked column on protein retention and the retention mechanism of proteins in the metal chalet affinity chromatography were discussed. PMID:15689030

  12. Electrolysis-reducing electrodes for electrokinetic devices.

    PubMed

    Erlandsson, Per G; Robinson, Nathaniel D

    2011-03-01

    Direct current electrokinetic systems generally require Faradaic reactions to occur at a pair of electrodes to maintain an electric field in an electrolyte connecting them. The vast majority of such systems, e.g. electrophoretic separations (capillary electrophoresis) or electroosmotic pumps (EOPs), employ electrolysis of the solvent in these reactions. In many cases, the electrolytic products, such as H+ and OH⁻ in the case of water, can negatively influence the chemical or biological species being transported or separated, and gaseous products such as O₂ and H₂ can break the electrochemical circuit in microfluidic devices. This article presents an EOP that employs the oxidation/reduction of the conjugated polymer poly(3,4-ethylenedioxythiophene), rather than electrolysis of a solvent, to drive flow in a capillary. Devices made with poly(3,4-ethylenedioxythiophene) electrodes are compared with devices made with Pt electrodes in terms of flow and local pH change at the electrodes. Furthermore, we demonstrate that flow is driven for applied potentials under 2 V, and the electrodes are stable for potentials of at least 100 V. Electrochemically active electrodes like those presented here minimize the disadvantage of integrated EOP in, e.g. lab-on-a-chip applications, and may open new possibilities, especially for battery-powered disposable point-of-care devices. PMID:21425174

  13. Electrokinetic remediation of PAH mixtures from kaolin.

    PubMed

    Alcántara, M T; Gómez, J; Pazos, M; Sanromán, M A

    2010-07-15

    Because of increased industrialisation and new manufacturing processes, elevated amounts of organic pollutants are released into the environment. Hydrophobic organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), are toxic and persistent contaminants that are not treatable by natural attenuation. In this work, electroremediation is proposed for cleaning soil contaminated by organic compounds. Model samples of kaolin clay polluted with a mixture of PAHs (fluoranthene, pyrene, and benzanthracene) were treated. Electroremediation of kaolin contaminated with a mixture of these three PAHs was carried out using a solution of 1% Tween 80 and 0.1 M Na(2)SO(4) as the processing fluid. Under these conditions, low removal was obtained. However, by using the same processing fluid and controlling the pH at 7 in the anode chamber, high electro-osmotic flow was detected. After the treatment, removal of around 40% of the PAHs was achieved. The created environment inside the soil during the electrokinetic treatment greatly influenced the process. The results of this work reveal the high potential for the application of the electroremediation process on soil polluted with different PAHs.

  14. Electrokinetic control of bacterial deposition and transport.

    PubMed

    Qin, Jinyi; Sun, Xiaohui; Liu, Yang; Berthold, Tom; Harms, Hauke; Wick, Lukas Y

    2015-05-01

    Microbial biofilms can cause severe problems in technical installations where they may give rise to microbially influenced corrosion and clogging of filters and membranes or even threaten human health, e.g. when they infest water treatment processes. There is, hence, high interest in methods to prevent microbial adhesion as the initial step of biofilm formation. In environmental technology it might be desired to enhance bacterial transport through porous matrices. This motivated us to test the hypothesis that the attractive interaction energy allowing cells to adhere can be counteracted and overcome by the shear force induced by electroosmotic flow (EOF, i.e. the water flow over surfaces exposed to a weak direct current (DC) electric field). Applying EOF of varying strengths we quantified the deposition of Pseudomonas fluorescens Lp6a in columns containing glass collectors and on a quartz crystal microbalance. We found that the presence of DC reduced the efficiency of initial adhesion and bacterial surface coverage by >85%. A model is presented which quantitatively explains the reduction of bacterial adhesion based on the extended Derjaguin, Landau, Verwey, and Overbeek (XDLVO) theory of colloid stability and the EOF-induced shear forces acting on a bacterium. We propose that DC fields may be used to electrokinetically regulate the interaction of bacteria with surfaces in order to delay initial adhesion and biofilm formation in technical installations or to enhance bacterial transport in environmental matrices.

  15. Electrolysis-reducing electrodes for electrokinetic devices.

    PubMed

    Erlandsson, Per G; Robinson, Nathaniel D

    2011-03-01

    Direct current electrokinetic systems generally require Faradaic reactions to occur at a pair of electrodes to maintain an electric field in an electrolyte connecting them. The vast majority of such systems, e.g. electrophoretic separations (capillary electrophoresis) or electroosmotic pumps (EOPs), employ electrolysis of the solvent in these reactions. In many cases, the electrolytic products, such as H+ and OH⁻ in the case of water, can negatively influence the chemical or biological species being transported or separated, and gaseous products such as O₂ and H₂ can break the electrochemical circuit in microfluidic devices. This article presents an EOP that employs the oxidation/reduction of the conjugated polymer poly(3,4-ethylenedioxythiophene), rather than electrolysis of a solvent, to drive flow in a capillary. Devices made with poly(3,4-ethylenedioxythiophene) electrodes are compared with devices made with Pt electrodes in terms of flow and local pH change at the electrodes. Furthermore, we demonstrate that flow is driven for applied potentials under 2 V, and the electrodes are stable for potentials of at least 100 V. Electrochemically active electrodes like those presented here minimize the disadvantage of integrated EOP in, e.g. lab-on-a-chip applications, and may open new possibilities, especially for battery-powered disposable point-of-care devices.

  16. Imidazolium-based ionic liquid-type surfactant as pseudostationary phase in micellar electrokinetic chromatography of highly hydrophilic urinary nucleosides.

    PubMed

    Rageh, Azza H; Pyell, Ute

    2013-11-01

    Ionic liquid (IL)-type surfactants have been shown to interact more strongly with polar compounds than traditionally used quaternary ammonium cationic surfactants. The aim of this study is to provide an alternative micellar electrokinetic chromatographic method (MEKC) for the analysis of urinary nucleosides in their ionic form at low surfactant concentration. This approach could overcome the use of high surfactant concentrations typically associated with the analysis of these highly hydrophilic metabolites as neutral species, which is frequently accompanied by high electric current, Joule heating and long analysis time. The investigated IL-type surfactant; 1-tetradecyl-3-methylimidazolium bromide (C14MImBr) is similar to the commonly employed cationic surfactant; tetradecyltrimethylammonium bromide (TTAB) but it provides a different separation selectivity. We employed C14MImBr micelles for the MEKC analysis of seven urinary nucleosides. The studied analytes possess a negative charge at pH 9.38 (exceptions are adenosine and cytidine which are neutral at this pH value). Borate imparts an additional negative charge to these compounds after complexation with the cis-diol functionality of the ribose unit, which in turn enables them to interact with the oppositely charged C14MImBr micelles via electrostatic (Coulomb) forces. The effect of the concentration of borate (the complexing, competing and buffering ion) on the effective electrophoretic mobilities and on the retention factors was investigated. The effective electrophoretic mobility data show that complexation between these nucleosides and borate occurs with high degree of complexation even at very low borate concentration (2.5 mmol L(-1) disodium tetraborate). In addition, we found that the retention factors are strongly dependent on the borate concentration being the highest when using the lowest borate concentration and they can be regulated by variation of either tetraborate concentration or the pH of the

  17. Fast Myoglobin Detection Using Nanofluidic Electrokinetic Trapping Technique

    NASA Astrophysics Data System (ADS)

    Chun, DongWon; Kim, Sang Hui; Song, Hyungwan; Kwak, Seungmin; Kim, YooChan; Seok, HyunGwang; Lee, Sang-Myung; Lee, Jeong Hoon

    2013-01-01

    We report on the preconcentration-enhanced fast collection of myoglobin protein for the rapid detection of myocardial infarction. We use a one-dimensional micro/nanofluidic chip for electrokinetic preconcentration and demonstrate that the preconcentration factor of 1 ng/ml Alexa Fluor 488-labeled myoglobin is ˜1000 within 200 s, where the protein had a weak negative charge, thereby making it hard to perform electrokinetic trapping for neutral-like proteins. The potential feasibility with new assay strategies for use in a rapid immunoassay screening test for myocardial infarction is discussed.

  18. Electrokinetic assembly of selenium and silver nanowires into macroscopic fibers.

    PubMed

    Wang, Michael C P; Zhang, Xin; Majidi, Elham; Nedelec, Kevin; Gates, Byron D

    2010-05-25

    Solution-phase synthesized nanowires with high aspect ratios can be a challenge to assemble into desired structures. As synthesized, these nanostructures readily bend and entangle with each other to form larger aggregates. This manuscript reports a general procedure for directing the assembly of semiconducting and metallic nanowires into fibers that can easily span distances >1 cm. Dispersions of these nanostructures in a low dielectric solution are organized by electrokinetic techniques into fibers that can be isolated from solution. Theoretical studies suggest that the assembled fibers adopt an orientation along electric field lines in the solution. The number of assembled fibers is a function of the duration of the assembly process, the magnitude of the electric potential, and the initial concentration of nanowires dispersed in solution. These findings offer a general method for the assembly of nanowires into macroscopic fibers of tunable dimensions. Fibers of selenium nanowires isolated from solution can reversibly bend in response to a source of electrostatic charges positioned in close proximity to the free-standing fiber. These flexible selenium fibers also exhibit a photoconductive response when illuminated with white light.

  19. Electrokinetically modulated peristaltic transport of power-law fluids.

    PubMed

    Goswami, Prakash; Chakraborty, Jeevanjyoti; Bandopadhyay, Aditya; Chakraborty, Suman

    2016-01-01

    The electrokinetically modulated peristaltic transport of power-law fluids through a narrow confinement in the form of a deformable tube is investigated. The fluid is considered to be divided into two regions - a non-Newtonian core region (described by the power-law behavior) which is surrounded by a thin wall-adhering layer of Newtonian fluid. This division mimics the occurrence of a wall-adjacent cell-free skimming layer in blood samples typically handled in microfluidic transport. The pumping characteristics and the trapping of the fluid bolus are studied by considering the effect of fluid viscosities, power-law index and electroosmosis. It is found that the zero-flow pressure rise is strongly dependent on the relative viscosity ratio of the near-wall depleted fluid and the core fluid as well as on the power-law index. The effect of electroosmosis on the pressure rise is strongly manifested at lower occlusion values, thereby indicating its importance in transport modulation for weakly peristaltic flow. It is also established that the phenomenon of trapping may be controlled on-the-fly by tuning the magnitude of the electric field: the trapping vanishes as the magnitude of the electric field is increased. Similarly, the phenomenon of reflux is shown to disappear due to the action of the applied electric field. These findings may be applied for the modulation of pumping in bio-physical environments by means of external electric fields.

  20. Evaluation of electrokinetic remediation of arsenic-contaminated soils.

    PubMed

    Kim, Soon-Oh; Kim, Won-Seok; Kim, Kyoung-Woong

    2005-09-01

    The potential of electrokinetic (EK) remediation technology has been successfully demonstrated for the remediation of heavy metal-contaminated fine-grained soils through laboratory scale and field application studies. Arsenic contamination in soil is a serious problem affecting both site use and groundwater quality. The EK technology was evaluated for the removal of arsenic from two soil samples; a kaolinite soil artificially contaminated with arsenic and an arsenic-bearing tailing-soil taken from the Myungbong (MB) gold mine area. The effectiveness of enhancing agents was investigated using three different types of cathodic electrolytes; deionized water (DIW), potassium phosphate (KH(2)PO(4)) and sodium hydroxide (NaOH). The results of the experiments on the kaolinite show that the potassium phosphate was the most effective in extracting arsenic, probably due to anion exchange of arsenic species by phosphate. On the other hand, the sodium hydroxide seemed to be the most efficient in removing arsenic from the tailing-soil. This result may be explained by the fact that the sodium hydroxide increased the soil pH and accelerated ionic migration of arsenic species through the desorption of arsenic species as well as the dissolution of arsenic-bearing minerals. PMID:16237600

  1. Analysis of post-harvest fungicides by micellar electrokinetic chromatography.

    PubMed

    Rodríguez, R; Picó, Y; Font, G; Mañes, J

    2001-07-27

    A method based on solid-phase extraction (SPE) and micellar electrokinetic chromatography (MEKC) was developed for the simultaneous determination of carbendazim, imazalil, methylthiophanate, O-phenylphenol, prochloraz, procimidone, thiabendazole and triadimefon residues in grape, lettuce, orange and tomato. Selectivity and resolution were studied changing the pH and the concentration of the buffer, the type and concentration of surfactant and the methanol content in the mobile phase. A buffer consisting of 4 mM borate with 75 mM sodium cholate (pH 9.2) gave the best results. The recoveries of the fungicides in spiked fruit and vegetable samples ranged from 30 to 105%, and the limits of detection were between 0.1 and 1 mg kg(-1). The reproducibility and repeatability of the combination of SPE pretreatment and MEKC were good for all the compounds, except for imazalil and O-phenylphenol in oranges, due to some matrix compounds interfering with the separation. The method was applied to post harvest treated samples, and the fungicides were sometimes detected at concentration levels lower than maximum residue limits (MRLs). PMID:11521888

  2. Electrokinetically modulated peristaltic transport of power-law fluids.

    PubMed

    Goswami, Prakash; Chakraborty, Jeevanjyoti; Bandopadhyay, Aditya; Chakraborty, Suman

    2016-01-01

    The electrokinetically modulated peristaltic transport of power-law fluids through a narrow confinement in the form of a deformable tube is investigated. The fluid is considered to be divided into two regions - a non-Newtonian core region (described by the power-law behavior) which is surrounded by a thin wall-adhering layer of Newtonian fluid. This division mimics the occurrence of a wall-adjacent cell-free skimming layer in blood samples typically handled in microfluidic transport. The pumping characteristics and the trapping of the fluid bolus are studied by considering the effect of fluid viscosities, power-law index and electroosmosis. It is found that the zero-flow pressure rise is strongly dependent on the relative viscosity ratio of the near-wall depleted fluid and the core fluid as well as on the power-law index. The effect of electroosmosis on the pressure rise is strongly manifested at lower occlusion values, thereby indicating its importance in transport modulation for weakly peristaltic flow. It is also established that the phenomenon of trapping may be controlled on-the-fly by tuning the magnitude of the electric field: the trapping vanishes as the magnitude of the electric field is increased. Similarly, the phenomenon of reflux is shown to disappear due to the action of the applied electric field. These findings may be applied for the modulation of pumping in bio-physical environments by means of external electric fields. PMID:26524260

  3. Electrokinetic instability effects in microchannels with and without nanofilm coatings.

    PubMed

    Fu, Lung-Ming; Hong, Ting-Fu; Wen, Chih-Yung; Tsai, Chien-Hsiung; Lin, Che-Hsin

    2008-12-01

    This paper presents a parametric experimental investigation into the electrokinetic instability (EKI) phenomenon within three different types of microfluidic device, namely T-type, cross-shaped, and cross-form with an expansion configuration. The critical electric field strength at which the EKI phenomenon is induced is examined as a function of the conductivity ratio, the microchannel width, the expansion ratio, and the surface treatment of the microchannel walls. It is found that the critical electric field strength associated with the onset of EKI is strongly dependent on the conductivity ratio of the two samples within the microfluidic device and reduces as the channel width increases. The surfaces of the microchannel walls are coated with hydrophilic or hydrophobic organic-based spin-on-glass (SOG) nanofilms for glass-based microchips. The experimental results indicate that no significant difference exists in the critical electric field strengths in the hydrophilic or hydrophobic SOG-coated microchannels, respectively. However, for a given conductivity ratio and microchannel width, the critical strength of the electric field is slightly lower in the SOG-coated microchannels than in the non-coated channels. In general, the results presented in this study demonstrate the potential for designing and controlling on-chip assays requiring the manipulation of samples with high conductivity gradients, and provide a useful general reference for avoiding EKI effects in capillary electrophoresis analysis applications. PMID:19130549

  4. Charged colloids and polyelectrolytes: from statics to electrokinetics

    NASA Astrophysics Data System (ADS)

    Löwen, H.; Esztermann, A.; Wysocki, A.; Allahyarov, E.; Messina, R.; Jusufi, A.; Hoffmann, N.; Gottwald, D.; Kahl, G.; Konieczny, M.; Likos, C. N.

    2005-01-01

    A review is given on recent studies of charged colloidal suspensions and polyelectrolytes both in static and non-equilibrium situations. As far as static equilibrium situations are concerned, we discuss three different problems: 1) Sedimentation density profiles in charged suspensions are shown to exhibit a stretched non-bariometric wing at large heights and binary suspensions under gravity can exhibit an analog of the brazil-nut effect known from granular matter, i.e. the heavier particles settle on top of the lighter ones. 2) Soft polyelectrolyte systems like polyelectrolyte stars and microgels show an ultra-soft effective interaction and this results into an unusual equilibrium phase diagram including reentrant melting transitions and stable open crystalline lattices. 3) The freezing transition in bilayers of confined charged suspensions is discussed and a reentrant behaviour is obtained. As far as nonequilibrium problems are concerned, we discuss an interface instability in oppositely driven colloidal mixtures and discuss possible approaches to simulate electrokinetic effects in charged suspensions.

  5. Evaluation of electrokinetic remediation of arsenic-contaminated soils.

    PubMed

    Kim, Soon-Oh; Kim, Won-Seok; Kim, Kyoung-Woong

    2005-09-01

    The potential of electrokinetic (EK) remediation technology has been successfully demonstrated for the remediation of heavy metal-contaminated fine-grained soils through laboratory scale and field application studies. Arsenic contamination in soil is a serious problem affecting both site use and groundwater quality. The EK technology was evaluated for the removal of arsenic from two soil samples; a kaolinite soil artificially contaminated with arsenic and an arsenic-bearing tailing-soil taken from the Myungbong (MB) gold mine area. The effectiveness of enhancing agents was investigated using three different types of cathodic electrolytes; deionized water (DIW), potassium phosphate (KH(2)PO(4)) and sodium hydroxide (NaOH). The results of the experiments on the kaolinite show that the potassium phosphate was the most effective in extracting arsenic, probably due to anion exchange of arsenic species by phosphate. On the other hand, the sodium hydroxide seemed to be the most efficient in removing arsenic from the tailing-soil. This result may be explained by the fact that the sodium hydroxide increased the soil pH and accelerated ionic migration of arsenic species through the desorption of arsenic species as well as the dissolution of arsenic-bearing minerals.

  6. Removal of MTBE from a clay soil using electrokinetic technique.

    PubMed

    Estabragh, A R; Bordbar, A T; Ghaziani, F; Javadi, A A

    2016-01-01

    Remediation of a soil contaminated with methyl tertiary butyl ether (MTBE) was studied by using the electrokinetic technique. A series of experimental tests were carried out on contaminated soil in an electro-osmotic apparatus at different applied gradients of voltage and time. The tests were conducted with distilled water and ethylenediaminetetra acetic acid (EDTA) solution as electrolyte. During each test the values of pH at anode and cathode reservoirs and also the discharge from cathode were measured. At the end of each test a number of soil samples were extracted from the middle of the soil at different distances from the anode and the removal of contaminant was measured by a gas chromatography apparatus. The results indicate that with EDTA as electrolyte the highest efficiency for removal of MTBE is achieved with 2.0 V/cm gradient and in the duration of 14 days. In addition, EDTA causes the values of pH to increase and decrease in the cathode and anode reservoirs, respectively. It also decreases the effluent and electro-osmotic permeability in comparison with distilled water. Experimental data were analysed by ANOVA and t-test methods. These statistical analyses showed significant difference (at 5% level) between the reference and other tests. PMID:26787321

  7. Determination of polymer log D distributions by micellar and microemulsion electrokinetic chromatography.

    PubMed

    Jin, Xiaoyun; Leclercq, Laurent; Cottet, Hervé

    2013-11-29

    The characterization of the hydrophobicity of polymer compounds in solution remains a challenging issue of importance, especially for biomedical or pharmaceutical applications. To our knowledge, there is no data of polymer hydrophobicity (log D) in the literature. In this work, for the first time, the log D distributions of cationic polymers were characterized using micellar or microemulsion electrokinetic chromatography at physiological pH. The log D distributions of the polymer samples were obtained from the electrophoretic/chromatographic retardation of the polymer derivatives in presence of neutral micelles (or neutral microemulsion), using small cationic molecules for calibration. Separating electrolytes were based on a TRIS–chloride buffer containing a neutral surfactant (polyoxyethyleneglycoldodecyl ether) for the formation of micelles (in water) or microemulsion (in water/n-pentanol mixture).The log D distributions obtained at pH 7.4 using this method were in good agreement with the chemical structures of cationic polypeptides: poly(lys, phe) 1:1 > poly(lys, tyr) 1:1 > poly(lys, trp) 4:1 > poly(lys, ser)3:1 > poly(l-lysine), where x:y represents the molar ratio of each amino acid in the copolymer. Weight average octanol–water log D values and the dispersion of the log D distribution were also defined and determined for each polymer sample.

  8. Simultaneous determination of lovastatin and citrinin in red yeast rice supplements by micellar electrokinetic capillary chromatography.

    PubMed

    Nigović, Biljana; Sertić, Miranda; Mornar, Ana

    2013-05-01

    Lovastatin is a main component of Monascus purpureus fermented red rice contributing to the lipid-lowering effect. Citrinin is a toxic fermentation by-product which can be found as a contaminant. An accurate, simple and rapid micellar electrokinetic capillary chromatographic method was developed for the first time for simultaneous determination of lovastatin present in lactone and hydroxy acid forms and citrinin in red rice products provided by different manufacturers and formulated in various dosage forms. Separation was achieved within only 2 min using 20 mM of phosphate buffer at pH 7.0 and 30 mM of sodium dodecyl sulphate at an applied voltage of 25 kV. Sensitivity crucial for detecting citrinin was enhanced by using an extended light path capillary. The results showed that the content of lovastatin and its acid form in dietary supplements were considerably different indicating the need for improved standardization in order to ensure efficiency and safety of these products. PMID:23265521

  9. Micellar electrokinetic capillary electrophoresis for rapid analysis of patulin in apple cider.

    PubMed

    Tsao, R; Zhou, T

    2000-11-01

    A micellar electrokinetic capillary chromatography (MECC) mode was applied to a capillary electrophoresis (CE) method, which was developed for detection and quantitation of patulin in apple ciders. This method used a small sample amount (2 mL) and consumed minimal organic solvent compared to the most commonly used HPLC methods. The sample preparation procedure of the CE method was also simpler than other chromatographic techniques developed for patulin analysis. Patulin was detected with a photodiode array detector at 273 nm. The standard curve was linear (r(2) = 0.9984) from 75 microgram/L to 121 microgram/mL with patulin working solutions corresponding to 3.8 microgram/L to 6.1 microgram/mL patulin in the sample. The linearity was better in a narrower range of concentrations (r(2) = 0.9999) from 75 microgram/L to 24.1 microgram/mL. The limit of detection of the method was 3.8 microgram/L. Patulin recoveries at 4 levels in spiked samples (10-121 microgram/L) ranged from 95.2 to 105.4%. The recoveries were 96. 9% and 99.2% for 2 levels (22.3 and 223 microgram/L, respectively) of patulin in infected apple samples. This method represents a unique alternative method for rapid and sensitive analysis of patulin in apple ciders. PMID:11087465

  10. Simultaneous determination of lovastatin and citrinin in red yeast rice supplements by micellar electrokinetic capillary chromatography.

    PubMed

    Nigović, Biljana; Sertić, Miranda; Mornar, Ana

    2013-05-01

    Lovastatin is a main component of Monascus purpureus fermented red rice contributing to the lipid-lowering effect. Citrinin is a toxic fermentation by-product which can be found as a contaminant. An accurate, simple and rapid micellar electrokinetic capillary chromatographic method was developed for the first time for simultaneous determination of lovastatin present in lactone and hydroxy acid forms and citrinin in red rice products provided by different manufacturers and formulated in various dosage forms. Separation was achieved within only 2 min using 20 mM of phosphate buffer at pH 7.0 and 30 mM of sodium dodecyl sulphate at an applied voltage of 25 kV. Sensitivity crucial for detecting citrinin was enhanced by using an extended light path capillary. The results showed that the content of lovastatin and its acid form in dietary supplements were considerably different indicating the need for improved standardization in order to ensure efficiency and safety of these products.

  11. Analysis of positional isomers of hydroxylated aromatic cytokinins by micellar electrokinetic chromatography.

    PubMed

    Ge, Liya; Yong, Jean Wan Hong; Tan, Swee Ngin; Yang, Xin Hao; Ong, Eng Shi

    2005-05-01

    A micellar electrokinetic chromatography (MEKC) method was developed for the separation of six positional isomers of hydroxylated aromatic cytokinins (topolin and topolin riboside), including ortho-topolin, meta-topolin, para-topolin, ortho-topolin riboside, meta-topolin riboside, and para-topolin riboside. Optimum resolution and analysis time (ca. 20 min) for the six aromatic cytokinin standards were achieved with a running buffer at pH 8.0 consisting of 20 mM boric acid, 50 mM sodium dodecyl sulfate (SDS), and 20% v/v methanol. The method has good reproducibility and has been successfully applied to detect the presence of a putative ortho-topolin in coconut water extract sample purified using C(18) and mixed-mode solid-phase extraction (SPE) columns. Other advantages of this MEKC method are short analysis time, low solvent consumption, and separation of positional isomers which could be achieved by a simple aqueous buffer system without the use of expensive chromatographic columns. In addition, a high-performance liquid chromatography (HPLC) method with baseline separation of the six topolin and topolin riboside standards was developed for the confirmation of the endogenous ortho-topolin in coconut water sample. Finally, the presence of ortho-topolin was further confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) based on its characteristic fragmentation pattern. PMID:15800967

  12. Remediation of Pb/Cr co-contaminated soil using electrokinetic process and approaching electrode technique.

    PubMed

    Ng, Yee-Sern; Sen Gupta, Bhaskar; Hashim, Mohd Ali

    2016-01-01

    Electrokinetic process has emerged as an important tool for remediating heavy metal-contaminated soil. The process can concentrate heavy metals into smaller soil volume even in the absence of hydraulic flow. This makes it an attractive soil pre-treatment method before other remediation techniques are applied such that the chemical consumption in the latter stage can be reduced. The present study evaluates the feasibility of electrokinetic process in concentrating lead (Pb) and chromium (Cr) in a co-contaminated soil using different types of wetting agents, namely 0.01 M NaNO3, 0.1 M citric acid and 0.1 M EDTA. The data obtained showed that NaNO3 and citric acid resulted in poor Pb electromigration in this study. As for Cr migration, these agents were also found to give lower electromigration rate especially at low pH region as a result of Cr(VI) adsorption and possible reduction into Cr(III). In contrast, EDTA emerged as the best wetting agent in this study as it formed water-soluble anionic complexes with both Pb and Cr. This provided effective one-way electromigration towards the anode for both ions, and they were accumulated into smaller soil volume with an enrichment ratio of 1.55-1.82. A further study on the application of approaching cathode in EDTA test showed that soil alkalisation was achieved, but this did not provide significant enhancement on electromigration for Pb and Cr. Nevertheless, the power consumption for electrokinetic process was decreased by 22.5%.

  13. Remediation of Pb/Cr co-contaminated soil using electrokinetic process and approaching electrode technique.

    PubMed

    Ng, Yee-Sern; Sen Gupta, Bhaskar; Hashim, Mohd Ali

    2016-01-01

    Electrokinetic process has emerged as an important tool for remediating heavy metal-contaminated soil. The process can concentrate heavy metals into smaller soil volume even in the absence of hydraulic flow. This makes it an attractive soil pre-treatment method before other remediation techniques are applied such that the chemical consumption in the latter stage can be reduced. The present study evaluates the feasibility of electrokinetic process in concentrating lead (Pb) and chromium (Cr) in a co-contaminated soil using different types of wetting agents, namely 0.01 M NaNO3, 0.1 M citric acid and 0.1 M EDTA. The data obtained showed that NaNO3 and citric acid resulted in poor Pb electromigration in this study. As for Cr migration, these agents were also found to give lower electromigration rate especially at low pH region as a result of Cr(VI) adsorption and possible reduction into Cr(III). In contrast, EDTA emerged as the best wetting agent in this study as it formed water-soluble anionic complexes with both Pb and Cr. This provided effective one-way electromigration towards the anode for both ions, and they were accumulated into smaller soil volume with an enrichment ratio of 1.55-1.82. A further study on the application of approaching cathode in EDTA test showed that soil alkalisation was achieved, but this did not provide significant enhancement on electromigration for Pb and Cr. Nevertheless, the power consumption for electrokinetic process was decreased by 22.5%. PMID:26330317

  14. Vibrational Spectroscopy of Chromatographic Interfaces

    SciTech Connect

    Jeanne E. Pemberton

    2011-03-10

    Chromatographic separations play a central role in DOE-supported fundamental research related to energy, biological systems, the environment, and nuclear science. The overall portfolio of research activities in the Separations and Analysis Program within the DOE Office of Basic Energy Sciences includes support for activities designed to develop a molecular-level understanding of the chemical processes that underlie separations for both large-scale and analytical-scale purposes. The research effort funded by this grant award was a continuation of DOE-supported research to develop vibrational spectroscopic methods to characterize the interfacial details of separations processes at a molecular level.

  15. [A novel multiple-channel apparatus for packing capillary chromatographic column and its application].

    PubMed

    Lü, Yayao; Hao, Feiran; Wang, Huanhuan; Fu, Bin; Qian, Xiaohong; Zhang, Yangjun

    2015-11-01

    A novel multiple-channel apparatus for packing capillary chromatographic column was designed and manufactured for packing six capillary chromatographic columns with close column efficiency at the same time. Briefly, it consists of a magnetic stirrer, a liquid chromatographic pump and a multiple-channel can. The reagents used for preparing ODS (C18) slurry and stirring condition of the magnetic stirrer were optimized in the study. Two batches of capillary chromatographic columns were packed under the optimum condition, and these packed capillary chromatographic columns were evaluated in the terms of peak capacity, sequence coverage, retention times of three peptide ions and column pressure using the tryptic digest of a bovine serum albumin (BSA) and detected by LC-MS in electrospray ionization (ESI) mode. The experimental results showed that the six capillary chromatographic columns packed at the same time had close column efficiencies, however, the column efficiencies of twelve capillary chromatographic columns packed at two times were significantly different. In addition, there was no significant column efficiency difference when packing one or six capillary chromatographic columns at the same time. The multiple-channel apparatus designed by us is simple, time-saving, and can be applied to pack capillary chromatographic columns with similar column efficiencies, thus it is of evident advantage over traditional one-channel apparatus.

  16. Investigation of the enantiomerization barriers of the phthalimidone derivatives EM12 and lenalidomide by dynamic electrokinetic chromatography.

    PubMed

    Walz, Sarah; Weis, Sylvia; Franz, Mareike; Rominger, Frank; Trapp, Oliver

    2015-03-01

    The phthalimidone derivatives EM12 and lenalidomide, which are both structurally related to thalidomide, are highly interesting drugs and very recently lenalidomide attracted great attention as an antitumor and immune-modulating drug in the therapy for multiple myeloma. EM12 and lenalidomide are chiral, and the stereogenic carbon C-3 in the piperidine-2,6-dione moiety of these phthalimidone derivatives is prone to interconversion due to keto-enol tautomerization. The knowledge of the enantiomerization barrier is mandatory for pharmacokinetic studies and to develop a tailored therapy using the enantiopure or racemic drug. Here, we used dynamic EKC in combination with direct-calculation methods to determine the enantiomerization barriers of EM12 and lenalidomide. The separations of the enantiomers of EM12 and lenalidomide were performed in 50 mM aqueous disodium hydrogen phosphate buffer at pH 8 and 50 mM aqueous sodium tetraborate buffer at pH 9.3, respectively, using 20 mg/mL heptakis-(2,3-diacetyl-6-sulfato)-β-CD as a chiral additive. Enantiomerization of the compounds during the electrokinetic chromatographic separation resulted in pronounced plateau formation between the well-separated enantiomers. Peak form analysis of the experimentally obtained interconversion profiles yielded the enantiomerization rate constants k1 of EM12 and lenalidomide as well as the kinetic activation parameters ΔG(‡), ΔH(‡‡), and ΔS(‡) of enantiomerization by the evaluation of temperature-dependent measurements. The enantiomerization barrier ΔG(‡) was determined to be 98.3 ± 1.0 kJ/mol; the activation parameters ΔH(‡) = 46.1 ± 2.4 kJ/mol and ΔS(‡) = -170 ± 61 J/(K·mol) for EM12 and ΔG(‡) = 91.5 ± 1.0 kJ/mol, ΔH(‡) = 62.4 ± 5.4 kJ/mol, and ΔS(‡) = -98 ± 7 J/(K·mol) for lenalidomide. These findings were corroborated by density functional theory calculations at the B3LYP/3-21G level of theory of the ground state and intermediates considering an

  17. Electrokinetic flow in a nanochannel with an overlapped electrical double layer

    NASA Astrophysics Data System (ADS)

    Song, Zhuorui

    Electrokinetic flows within an overlapped Electrical Double Layer (EDL), which are not well-understood, were theoretically investigated in this study with the particular attention on the consideration of hydronium ions in the EDL. Theoretical models for fully-developed steady pressure-driven flow for salt-free water or a binary salt solution in a slit-like nanochannel connecting to two reservoirs were developed. The transient flow in such a domain was also simulated from static state to the final steady state. In these models, the Poisson equation and the Nernst-Planck equation were solved either by analytic methods or by the finite element method. Surface adsorption-desorption equilibrium and water equilibrium were considered to account for the proton exchange at the surface and in the fluid. These models were the first to include those comprehensive processes that are uniquely important for overlapped EDL scenarios. This study improves the understanding of electrokinetic flows within an overlapped EDL by demonstrating the profound impact of hydronium ions on the EDL structure. In the steady flow of potassium chloride solutions, hydronium ions are more enriched than potassium ions by up to 2~3 orders of magnitude, making the electrokinetic effects greatly depressed. The unequal enrichment effects of counterions were omitted in the traditional theory partially because the transient is extremely slow. The simulation results show that a concentration hump of hydronium ions initially forming at the channel entrance gradually expands over the whole channel in a way similar to the concentration plug flow moving downstream. The time required for the flow to reach the steady state could be as long as thousands of times the hydraulic retention time, dependent on the degree of the EDL overlap. This study improves the fundamental understanding for nanofluidic flows.

  18. General electrokinetic model for concentrated suspensions in aqueous electrolyte solutions: Electrophoretic mobility and electrical conductivity in static electric fields.

    PubMed

    Carrique, Félix; Ruiz-Reina, Emilio; Roa, Rafael; Arroyo, Francisco J; Delgado, Ángel V

    2015-10-01

    In recent years different electrokinetic cell models for concentrated colloidal suspensions in aqueous electrolyte solutions have been developed. They share some of its premises with the standard electrokinetic model for dilute colloidal suspensions, in particular, neglecting both the specific role of the so-called added counterions (i.e., those released by the particles to the solution as they get charged), and the realistic chemistry of the aqueous solution on such electrokinetic phenomena as electrophoresis and electrical conductivity. These assumptions, while having been accepted for dilute conditions (volume fractions of solids well below 1%, say), are now questioned when dealing with concentrated suspensions. In this work, we present a general electrokinetic cell model for such kind of systems, including the mentioned effects, and we also carry out a comparative study with the standard treatment (the standard solution only contains the ions that one purposely adds, without ionic contributions from particle charging or water chemistry). We also consider an intermediate model that neglects the realistic aqueous chemistry of the solution but accounts for the correct contribution of the added counterions. The results show the limits of applicability of the classical assumptions and allow one to better understand the relative role of the added counterions and ions stemming from the electrolyte in a realistic aqueous solution, on electrokinetic properties. For example, at low salt concentrations the realistic effects of the aqueous solution are the dominant ones, while as salt concentration is increased, it is this that progressively takes the control of the electrokinetic response for low to moderate volume fractions. As expected, if the solids concentration is high enough the added counterions will play the dominant role (more important the higher the particle surface charge), no matter the salt concentration if it is not too high. We hope this work can help in

  19. General electrokinetic model for concentrated suspensions in aqueous electrolyte solutions: Electrophoretic mobility and electrical conductivity in static electric fields.

    PubMed

    Carrique, Félix; Ruiz-Reina, Emilio; Roa, Rafael; Arroyo, Francisco J; Delgado, Ángel V

    2015-10-01

    In recent years different electrokinetic cell models for concentrated colloidal suspensions in aqueous electrolyte solutions have been developed. They share some of its premises with the standard electrokinetic model for dilute colloidal suspensions, in particular, neglecting both the specific role of the so-called added counterions (i.e., those released by the particles to the solution as they get charged), and the realistic chemistry of the aqueous solution on such electrokinetic phenomena as electrophoresis and electrical conductivity. These assumptions, while having been accepted for dilute conditions (volume fractions of solids well below 1%, say), are now questioned when dealing with concentrated suspensions. In this work, we present a general electrokinetic cell model for such kind of systems, including the mentioned effects, and we also carry out a comparative study with the standard treatment (the standard solution only contains the ions that one purposely adds, without ionic contributions from particle charging or water chemistry). We also consider an intermediate model that neglects the realistic aqueous chemistry of the solution but accounts for the correct contribution of the added counterions. The results show the limits of applicability of the classical assumptions and allow one to better understand the relative role of the added counterions and ions stemming from the electrolyte in a realistic aqueous solution, on electrokinetic properties. For example, at low salt concentrations the realistic effects of the aqueous solution are the dominant ones, while as salt concentration is increased, it is this that progressively takes the control of the electrokinetic response for low to moderate volume fractions. As expected, if the solids concentration is high enough the added counterions will play the dominant role (more important the higher the particle surface charge), no matter the salt concentration if it is not too high. We hope this work can help in

  20. Ion-exchange chromatographic analysis of peroxynitric acid.

    PubMed

    Nakashima, Yoichi; Ikawa, Satoshi; Tani, Atsushi; Kitano, Katsuhisa

    2016-01-29

    Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system. The fraction for the peroxynitric acid peak was collected. Ion-exchange chromatographic analysis of this fraction, after standing at room temperature for 24h, showed that the decomposition products were mainly nitrate ions with a very small amount of nitrous acid. The peroxynitric acid peak area correlated perfectly with the total amount of decomposition products. The ion-exchange chromatographic isolation allowed us to evaluate the molar extinction coefficient of peroxynitric acid precisely in a wider wavelength range than previous reports. The value decreases monotonically from 1729±26M(-1)cm(-1) at 200nm to 12.0±0.5M(-1)cm(-1) at 290nm.

  1. Reactor-chromatographic determination of vinyl chloride in polyvinyl chloride

    SciTech Connect

    Berezkin, V.G.

    1986-08-01

    The authors carry out a chromatographic study of the volatile products that evolve when various grades of domestic polyvinyl chloride are heated, to determine the concentration of residual monomer. To find vinyl chloride in complex mixtures of air pollutants the authors used sorptive reaction concentration of impurities. This new combination of methods is based on preliminary separation at the sampling stage of impurities that interfere in the analysis, followed by concentration of the desired components in a trap with an adsorbent, and chromatographic determination of the concentrated trace materials. The method obtains low vinyl chloride concentrations (down to 10/sup -4/-10/sup -5/ wt. %) with +/-5 relative error.

  2. Electrokinetic treatment of contaminated soils, sludges, and lagoons. Final report

    SciTech Connect

    Wittle, J.K.; Pamukcu, S.

    1993-04-01

    The electrokinetic process is an emerging technology for in-situ soil decontamination, in which chemical species, both ionic and nonionic are transported to an electrode site in soil. These products are subsequently removed from the ground via collection systems engineered for each specific application. Electrokinetics refer to movement of water, ions and charged particles relative to one another under the action of an applied direct current electric field. In a porous compact matrix of surface charged particles such as soil, the ion containing pore fluid may be made to flow to collection sites under the applied field. This report describes the effort undertaken to investigate electrokinetically enhanced transport of soil contaminants in synthetic systems. These systems consisted of clay or clay-sand mixtures containing known concentration of a selected heavy metal salt solution or an organic compound. Metals, surrogate radio nuclides and organic compounds evaluated in the program were representatives of those found at a majority of DOE sites. Degree of removal of these metals from soil by the electrokinetic treatment process was assessed through the metal concentration profiles generated across the soil between the electrodes. The best removals, from about 85 to 95% were achieved at the anode side of the soil specimens. Transient pH change had an effect on the metal movement via transient creation of different metal species with different ionic mobilities, as well as changing of the surface characteristics of the soil medium.

  3. Electrokinetic Properties of Lubricin Antiadhesive Coatings in Microfluidic Systems.

    PubMed

    Greene, George W; Duffy, Emer; Shallan, Aliaa; Wuethrich, Alain; Paull, Brett

    2016-02-23

    Lubricin is a glycoprotein found in articular joints which has long been recognized as being an important biological boundary lubricant molecule and, more recently, an impressive antiadhesive that readily self-assembles into a well ordered, polymer brush layer on virtually any substrate. The lubricin molecule possesses an overabundance of anionic charge, a property that is atypical among antiadhesive molecules, that enables its use as a coating for applications involving electrokinetic processes such as electrophoresis and electroosmosis. Coating the surfaces of silica and polymeric microfluidic devices with self-assembled lubricin coatings affords a unique combination of excellent fouling resistance and high charge density that enables notoriously "sticky" biomolecules such as proteins to be used and controlled electrokinetically in the device without complications arising from nonspecific adsorption. Using capillary electrophoresis, we characterized the stability, uniformity, and electrokinetic properties of lubricin coatings applied to silica and PTFE capillaries over a range of run buffer pHs and when exposed to concentrated solutions of protein. In addition, we demonstrate the effectiveness of lubricin as a coating to minimize nonspecific protein adsorption in an electrokinetically controlled polydimethylsiloxane/silica microfluidic device.

  4. An AC electrokinetics facilitated biosensor cassette for rapid pathogen identification.

    PubMed

    Ouyang, Mengxing; Mohan, Ruchika; Lu, Yi; Liu, Tingting; Mach, Kathleen E; Sin, Mandy L Y; McComb, Mason; Joshi, Janhvi; Gau, Vincent; Wong, Pak Kin; Liao, Joseph C

    2013-07-01

    To develop a portable point-of-care system based on biosensors for common infectious diseases such as urinary tract infection, the sensing process needs to be implemented within an enclosed fluidic system. On chip sample preparation of clinical samples remains a significant obstacle to achieving robust sensor performance. Herein AC electrokinetics is applied in an electrochemical biosensor cassette to enhance molecular convection and hybridization efficiency through electrokinetics induced fluid motion and Joule heating induced temperature elevation. Using E. coli as an exemplary pathogen, we determined the optimal electrokinetic parameters for detecting bacterial 16S rRNA in the biosensor cassette based on the current output, signal-to-noise ratio, and limit of detection. In addition, a panel of six probe sets targeting common uropathogenic bacteria was demonstrated. The optimized parameters were also validated using patient-derived clinical urine samples. The effectiveness of electrokinetics for on chip sample preparation will facilitate the implementation of point-of-care diagnosis of urinary tract infection in the future.

  5. MICELLAR ELECTROKINETIC CHROMATOGRAPHY-MASS SPECTROMETRY (R823292)

    EPA Science Inventory

    The combination of micellar electrokinetic chromatography (MEKC) with mass spectrometry (MS) is very attractive for the direct identification of analyte molecules, for the possibility of selectivity enhancement, and for the structure confirmation and analysis in a MS-MS mode. The...

  6. Evaluation of electrode configuration and mode of DC power for improvement of electrokinetic soil remediation

    NASA Astrophysics Data System (ADS)

    Kim, Soon-Oh; Lee, Woo Chun; Lee, Sang Woo; Lee, Byung-Tae

    2014-05-01

    Electrokinetic soil remediation is also called electrokinetic soil processing, electroreclamation, and electrochemical decontamination. The electrokinetic technique needs a low-level direct current of the order of mA/cm2 between electrodes to remove contaminants. The electrokinetic technique is one of the most promising remediation processes, and offers high efficiency and time effectiveness in the decontamination of low-permeability soils contaminated with heavy metals, radionuclides, or organic compounds. The significance of this technique is attributed to its low operational cost and potential applicability to a wide range of contaminant types, and these benefits have resulted in the initiation of numerous studies into its use for waste remediation. Electrode configuration is crucial for cost-effectiveness and overall efficacy of the elelectrokinetic processing, particularly in its field implementation. We investigated the effectiveness of various electrode arrays which can be grouped into one-dimensional (1-D) and two-dimensional (2-D) ones. Normally, the DC electricity of full wave has been used to remove contaminants from soils using elelectrokinetic processing. However, application of half-wave DC power can be also taken into account to improve efficacy of the processing, because it generates pulse power and accelerates the migration of contaminants within soils. We empirically evaluated the effect of type of DC electricity on the overall performance of the electrokinetic soil processing. The 1-D configuration with 5 electrode pairs showed the least total electric power, but that consumed in only the soil cell was less in the 2-D arrays than in 1-D ones. Particularly, most of the electric power is likely to be consumed in the electrode compartments, and the electric resistance in the electrode parts should be reduced to save the electric energy cost in the whole processing. In terms of removal efficiencies of 5 heavy metal contaminants, overall efficiency

  7. Mobilization of phenol and dichlorophenol in unsaturated soils by non-uniform electrokinetics.

    PubMed

    Luo, Qishi; Zhang, Xihui; Wang, Hui; Qian, Yi

    2005-06-01

    The poor mobility of organic pollutants in contaminated sites frequently results in slow remediation processes. Organics, especially hydrophobic compounds, are generally retained strongly in soil matrix as a result of sorption, sequestration, or even formation into non-aqueous-phase liquids and their mobility is thus greatly reduced. The objective of this study was to evaluate the feasibility of using non-uniform electrokinetic transport processes to enhance the mobility of organic pollutants in unsaturated soils with no injection reagents. Phenol and 2,4-dichlorophenol (2,4-DCP), and kaolin and a natural sandy loam soil were selected as model organics and soils, respectively. The results showed that non-uniform electrokinetics can accelerate the desorption and movement of phenol and 2,4-DCP in unsaturated soils. Electromigration and electroosmotic flow were the main driving forces, and their role in the mobilization of phenol and 2,4-DCP varied with soil pH. The movement of 2,4-DCP in the sandy loam towards the anode (about 1.0 cmd(-1)V(-1)) was 1.0-1.5 cmd(-1)V(-1) slower than that in the kaolin soil, but about 0.5 cmd(-1)V(-1) greater than that of phenol in the sandy loam. When the sandy loam was adjusted to pH 9.3, the movement of phenol and 2,4-DCP towards the anode was about twice and five times faster than that at pH 7.7, respectively. The results also demonstrated that the movement of phenol and 2,4-DCP in soils can be easily controlled by regulating the operational mode of electric field. It is believed that non-uniform electrokinetics has the potential for practical application to in situ remediation of organics-contaminated sites. PMID:15857640

  8. Removal of organic pollutants and heavy metals in soils by electrokinetic remediation.

    PubMed

    Ricart, M T; Pazos, M; Gouveia, S; Cameselle, C; Sanroman, M A

    2008-07-01

    In this work, the feasibility of electrokinetic remediation for the restoration of polluted soil with organic and inorganic compounds had been development and evaluated using a model soil sample. The model soil was prepared with kaolinite clay artificially polluted in the laboratory with chromium and an azo dye: Reactive Black 5 (RB5). The electromigration of Cr in a spiked kaolinite sample was studied in alkaline conditions. Despite of the high pH registered in the kaolinite sample (around pH 9.5), Cr migrated towards the cathode and it was accumulated in the cathode chamber forming a white precipitate. The removal was not complete, and 23% of the initial Cr was retained into the kaolinite sample close to the cathode side. The azo dye RB5 could be effectively removed from kaolinite by electrokinetics and the complete cleanup of the kaolinite could be achieved in alkaline environment. In this condition, RB5 formed an anion that migrated towards the anode where it was accumulated and quickly degraded upon the electrode surface. The electrokinetic treatment of a kaolinite sample polluted with both Cr and RB5 yielded very good results. The removal of Cr was improved compared to the experiment where Cr was the only pollutant, and RB5 reached a removal as high as 95%. RB5 was removed by electromigration towards the anode, where the dye was degraded upon the surface of the electrode by electrochemical oxidation. Cr was transported towards the cathode by electromigration and electroosmosis. It is supposed that the interaction among RB5 and Cr into the kaolinite sample prevented premature precipitation and allow Cr to migrate and concentrate in the cathode chamber. PMID:18569297

  9. Utilization of Electrokinetics in Remediation of Low Permeability Sediments Contaminated With Organic Compounds

    NASA Astrophysics Data System (ADS)

    Reynolds, D. A.; Thomas, D. G.; Jones, E. H.; Yusoff, I.

    2006-12-01

    Remediation of contaminated sites is an inherently difficult and time consuming process for a large number of reasons, some of the most significant being the complexity of stratigraphy and local scale geology across a wide range of scales; the heterogeneity of sedimentary deposits even when considering small scales, and the ineffectiveness of existing technologies. The traditional use of in situ chemical/biological treatments, while successful for remediation in their own right at some sites, have limited application at sites with complex geology and where NAPL is present. Electrokinetics, the migration of charged compounds under an electrical gradient, was investigated in the context of a remediation technique for dissolved phase contamination in low permeability environments. The target contaminant for the study was Trichloroethene (TCE), and the remediation compound was Potassium Permanganate. Experiments were performed in column scale and tank scale apparatuses, where a voltage potential was placed across or within a porous media, and the migration rate measured or visually observed. TCE contaminated cores were subjected to potassium permanganate remediation through diffusion transport alone, and various formulations of voltage potentials. Electrokinetics was found to migrate a dilute solution of potassium permanganate through low permeability porous media, several orders of magnitude faster than diffusion transport alone. The migration rate was found to be directly proportional to the applied voltage, with significant migration factors occurring for field-scale achievable voltages of 1-2 V/cm. The electrokinetic migration was found to be a threshold phenomenon, with a minimum applied voltage being required to offset electroosmotic flux and pore pressure factors. The demonstrated technique has significant potential for the remediation of contaminated low permeability media, through the use of potassium permanganate, and other approaches.

  10. Resistivity imaging during electrokinetic remediation of sediments: practical challenges in the field

    NASA Astrophysics Data System (ADS)

    Masi, Matteo; Ceccarini, Alessio; Iannelli, Renato

    2016-04-01

    The use of geophysical techniques such as electrical resistivity and impedance tomography have proven to be effective for the investigation and monitoring of a variety of environmental processes. This study investigates the possibility of using resistivity imaging to monitor the progress of electrokinetic remediation, a decontamination process based on electrochemical methods. The resistivity is a parameter of great theoretical and practical interest. On one side, resistivity is strictly related to the pore fluid composition and provides information about the chemical state of the material subjected to remediation. On the other side, knowing the evolution and distribution of resistivity is of practical importance both at the design stage and during operation because it directly affects the electrical energy expenditures. Monitoring of electrokinetic processes both in laboratory and in field is usually carried out by point measurements and sample collection from discrete locations. Resistivity imaging is effective in providing low-cost, non-destructive, high space and time resolution mapping. During electrokinetic remediation an electric field is applied to the contaminated matrix to extract the pollutants. In the field, array of electrodes are generally employed to apply the electric field, arranged in a two-dimensional grid. The electrodes are installed inside wells to allow the circulation of electrolytes employed to enhance the extraction of the pollutants. In this study we describe the practical challenges both in the measurements and in the data processing encountered during the tomographic imaging of marine sediments subjected to electrokinetic remediation in a 150 m3 ex-situ treatment plant. In such system there are a number of constraints to overcome in order to obtain an effective tomographic image of the sediments: (1) the electric field applied for remediation cannot be powered off, thus this field represents the source for current injection for the

  11. High-capacity pressurized continuous chromatograph

    SciTech Connect

    Begovich, J.M.; Byers, C.H.; Sisson, W.G.

    1983-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everwhere else around the annulus. The rotation of the sorbent bed causes the separation components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter. The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-..mu..m0-diam Dowex 50W-X8 cation exchange resin was used as the bed material. The nickel concentration of the feed was varied tenfold, from 136.1 to approximately 1400 meq/L. The combined effects of the bed loading and annulus width were studied and compared with nonlinear theory.

  12. High-capacity pressurized continuous chromatograph

    SciTech Connect

    Begovich, J.M.; Byers, C.H.; Sisson, W.G.

    1983-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everywhere else around the annulus. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter. The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-..mu..m-diam Dowex 50W-X8 cation exchange resin was used as the bed material. The nickel concentration of the feed was varied tenfold, from 136.1 to approximately 1400 meq/L. The combined effects of the bed loading and annulus width were studied and compared with nonlinear theory. 17 references, 9 figures, 1 table.

  13. High-capacity pressurized continuous chromatograph

    SciTech Connect

    Begovich, J.M.; Byers, C.H.; Sisson, W.G.

    1983-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everywhere else around the annulus. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter. The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-..mu..m-diam Dowex 50W-X8 cation exchange resin was used as the bed material. The nickel concentration of the feed was varied tenfold, from 136.1 to approximately 1400 meq/L. The combined effects of the bed loading and annulus width were studied and compared with nonlinear theory. 9 figures, 1 table.

  14. Particle morphology and mineral structure of heavy metal-contaminated kaolin soil before and after electrokinetic remediation.

    PubMed

    Roach, Nicole; Reddy, Krishna R; Al-Hamdan, Ashraf Z

    2009-06-15

    This study aims to characterize the physical distribution of heavy metals in kaolin soil and the chemical and structural changes in kaolinite minerals that result from electrokinetic remediation. Three bench-scale electrokinetic experiments were conducted on kaolin that was spiked with Cr(VI) alone, Ni (II) alone, and a combination of Cr(VI), Ni(II) and Cd(II) under a constant electric potential of 1VDC/cm for a total duration of 4 days. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses were performed on the soil samples before and after electrokinetic remediation. Results showed that the heavy metal contaminant distribution in the soil samples was not observable using TEM and EDX. EDX detected nickel and chromium on some kaolinite particles and titanium-rich, high-contrast particles, but no separate phases containing the metal contaminants were detected. Small amounts of heavy metal contaminants that were detected by EDX in the absence of a visible phase suggest that ions are adsorbed to kaolinite particle surfaces as a thin coating. There was also no clear correlation between semiquantitative analysis of EDX spectra and measured total metal concentrations, which may be attributed to low heavy metal concentrations and small size of samples used. X-ray diffraction analyses were aimed to detect any structural changes in kaolinite minerals resulting from EK. The diffraction patterns showed a decrease in peak height with decreasing soil pH value, which indicates possible dissolution of kaolinite minerals during electrokinetic remediation. Overall this study showed that the changes in particle morphology were found to be insignificant, but a relationship was found between the crystallinity of kaolin and the pH changes induced by the applied electric potential. PMID:19013716

  15. Particle morphology and mineral structure of heavy metal-contaminated kaolin soil before and after electrokinetic remediation.

    PubMed

    Roach, Nicole; Reddy, Krishna R; Al-Hamdan, Ashraf Z

    2009-06-15

    This study aims to characterize the physical distribution of heavy metals in kaolin soil and the chemical and structural changes in kaolinite minerals that result from electrokinetic remediation. Three bench-scale electrokinetic experiments were conducted on kaolin that was spiked with Cr(VI) alone, Ni (II) alone, and a combination of Cr(VI), Ni(II) and Cd(II) under a constant electric potential of 1VDC/cm for a total duration of 4 days. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses were performed on the soil samples before and after electrokinetic remediation. Results showed that the heavy metal contaminant distribution in the soil samples was not observable using TEM and EDX. EDX detected nickel and chromium on some kaolinite particles and titanium-rich, high-contrast particles, but no separate phases containing the metal contaminants were detected. Small amounts of heavy metal contaminants that were detected by EDX in the absence of a visible phase suggest that ions are adsorbed to kaolinite particle surfaces as a thin coating. There was also no clear correlation between semiquantitative analysis of EDX spectra and measured total metal concentrations, which may be attributed to low heavy metal concentrations and small size of samples used. X-ray diffraction analyses were aimed to detect any structural changes in kaolinite minerals resulting from EK. The diffraction patterns showed a decrease in peak height with decreasing soil pH value, which indicates possible dissolution of kaolinite minerals during electrokinetic remediation. Overall this study showed that the changes in particle morphology were found to be insignificant, but a relationship was found between the crystallinity of kaolin and the pH changes induced by the applied electric potential.

  16. Note on the chromatographic analyses of marine polyunsaturated fatty acids

    USGS Publications Warehouse

    Schultz, D.M.; Quinn, J.G.

    1977-01-01

    Gas-liquid chromatography was used to study the effects of saponification/methylation and thin-layer chromatographic isolation on the analyses of polyunsaturated fatty acids. Using selected procedures, the qualitative and quantitative distribution of these acids in marine organisms can be determined with a high degree of accuracy. ?? 1977 Springer-Verlag.

  17. Coupled electrokinetics-adsorption technique for simultaneous removal of heavy metals and organics from saline-sodic soil.

    PubMed

    Lukman, Salihu; Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat; Bukhari, Alaadin

    2013-01-01

    In situ remediation technologies for contaminated soils are faced with significant technical challenges when the contaminated soil has low permeability. Popular traditional technologies are rendered ineffective due to the difficulty encountered in accessing the contaminants as well as when employed in settings where the soil contains mixed contaminants such as petroleum hydrocarbons, heavy metals, and polar organics. In this study, an integrated in situ remediation technique that couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the efficiency of contaminant removal. For the 21-day period of continuous electrokinetics-adsorption experimental run, efficiency for the removal of Zn, Pb, Cu, Cd, Cr, Hg, phenol, and kerosene was found to reach 26.8, 55.8, 41.0, 34.4, 75.9, 92.49, 100.0, and 49.8%, respectively. The results obtained suggest that integrating adsorption into electrokinetic technology is a promising solution for removal of contaminant mixture from saline-sodic soils.

  18. Coupled Electrokinetics-Adsorption Technique for Simultaneous Removal of Heavy Metals and Organics from Saline-Sodic Soil

    PubMed Central

    Lukman, Salihu; Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat; Bukhari, Alaadin

    2013-01-01

    In situ remediation technologies for contaminated soils are faced with significant technical challenges when the contaminated soil has low permeability. Popular traditional technologies are rendered ineffective due to the difficulty encountered in accessing the contaminants as well as when employed in settings where the soil contains mixed contaminants such as petroleum hydrocarbons, heavy metals, and polar organics. In this study, an integrated in situ remediation technique that couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the efficiency of contaminant removal. For the 21-day period of continuous electrokinetics-adsorption experimental run, efficiency for the removal of Zn, Pb, Cu, Cd, Cr, Hg, phenol, and kerosene was found to reach 26.8, 55.8, 41.0, 34.4, 75.9, 92.49, 100.0, and 49.8%, respectively. The results obtained suggest that integrating adsorption into electrokinetic technology is a promising solution for removal of contaminant mixture from saline-sodic soils. PMID:24235885

  19. Coupled electrokinetics-adsorption technique for simultaneous removal of heavy metals and organics from saline-sodic soil.

    PubMed

    Lukman, Salihu; Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat; Bukhari, Alaadin

    2013-01-01

    In situ remediation technologies for contaminated soils are faced with significant technical challenges when the contaminated soil has low permeability. Popular traditional technologies are rendered ineffective due to the difficulty encountered in accessing the contaminants as well as when employed in settings where the soil contains mixed contaminants such as petroleum hydrocarbons, heavy metals, and polar organics. In this study, an integrated in situ remediation technique that couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the efficiency of contaminant removal. For the 21-day period of continuous electrokinetics-adsorption experimental run, efficiency for the removal of Zn, Pb, Cu, Cd, Cr, Hg, phenol, and kerosene was found to reach 26.8, 55.8, 41.0, 34.4, 75.9, 92.49, 100.0, and 49.8%, respectively. The results obtained suggest that integrating adsorption into electrokinetic technology is a promising solution for removal of contaminant mixture from saline-sodic soils. PMID:24235885

  20. The Influence of Dielectric Decrement on Electrokinetics.

    PubMed

    Zhao, Hui; Zhai, Shengjie

    2013-06-01

    We treat the dielectric decrement induced by excess ion polarization as a source of ion specificity and explore its impact on electrokinetics. We employ a modified Poisson-Nernst-Planck (PNP) equations accounting for the dielectric decrement. The dielectric decrement is determined by the excess ion polarization parameter α and when α = 0 the standard PNP model is recovered. Our model shows that ions saturate at large zeta potentials (ζ). Because of ion saturation, a condensed counterion layer forms adjacent to the charged surface, introducing a new length scale, the thickness of the condensed layer (lc ). For the electro-osmotic mobility, the dielectric decrement weakens the electro-osmotic flow owing to the decrease of the dielectric permittivity. At large ζ, when α ≠ 0, the electro-osmotic mobility is found to be proportional to ζ/2, in contrast to ζ predicted by the standard PNP model. This is attributed to ion saturation at large ζ. In terms of the electrophoretic mobility Me , we carry out both an asymptotic analysis in the thin-double-layer limit and solve the full modified PNP model to compute Me . Our analysis reveals that the impact of the dielectric decrement is intriguing. At small and moderate ζ, the dielectric decrement decreases Me with an increasing α. At large ζ, it is well known that the surface conduction becomes significant and plays an important role in determining Me . It is observed that the dielectric decrement effectively reduces the surface conduction. Hence in stark contrast, Me increases as α increases. Our predictions of the contrast dependence of the mobility on α at different zeta potentials qualitatively agree with experimental results on the dependence of the mobility among ions and provide a possible explanation for such ion specificity. Finally, the comparisons between the thin-double-layer asymptotic analysis and the full simulations of the modified PNP model suggest that at large ζ the validity of the thin

  1. Electrokinetic remediation of six emerging organic contaminants from soil.

    PubMed

    Guedes, Paula; Mateus, Eduardo P; Couto, Nazaré; Rodríguez, Yadira; Ribeiro, Alexandra B

    2014-12-01

    Some organic contaminants can accumulate in organisms and cause irreversible damages in biological systems through direct or indirect toxic effects. In this study the feasibility of the electrokinetic (EK) process for the remediation of 17β-oestradiol (E2), 17α-ethinyloestradiol (EE2), bisphenol A (BPA), nonylphenol (NP), octylphenol (OP) and triclosan (TCS) in soils was studied in a stationary laboratory cell. The experiments were conducted using a silty loam soil (S2) at 0, 10 and 20mA and a sandy soil (S3) at 0 and 10 mA. A pH control in the anolyte reservoir (pH>13) at 10 mA was carried out using S2, too. Photo and electrodegradation experiments were also fulfilled. Results showed that EK is a viable method for the remediation of these contaminants, both through mobilization by electroosmotic flow (EOF) and electrodegradation. As EOF is very sensible to soil pH, the control in the anolyte increased EOF rate, consequently enhancing contaminants mobilization towards the cathode end. The extent of the mobilization towards the electrode end was mainly dependent on compounds solubility and octanol-water partition coefficient. In the last 24h of experiments, BPA presented the highest mobilization rate (ca. 4 μg min(-1)) with NP not being detected in the catholyte. At the end of all experiments the percentage of contaminants that remained in the soil ranged between 17 and 50 for S2, and between 27 and 48 for S3, with no statistical differences between treatments. The mass balance performed showed that the amount of contaminant not detected in the cell is similar to the quantity that potentially may suffer photo and electrodegradation.

  2. Electrokinetic remediation of six emerging organic contaminants from soil.

    PubMed

    Guedes, Paula; Mateus, Eduardo P; Couto, Nazaré; Rodríguez, Yadira; Ribeiro, Alexandra B

    2014-12-01

    Some organic contaminants can accumulate in organisms and cause irreversible damages in biological systems through direct or indirect toxic effects. In this study the feasibility of the electrokinetic (EK) process for the remediation of 17β-oestradiol (E2), 17α-ethinyloestradiol (EE2), bisphenol A (BPA), nonylphenol (NP), octylphenol (OP) and triclosan (TCS) in soils was studied in a stationary laboratory cell. The experiments were conducted using a silty loam soil (S2) at 0, 10 and 20mA and a sandy soil (S3) at 0 and 10 mA. A pH control in the anolyte reservoir (pH>13) at 10 mA was carried out using S2, too. Photo and electrodegradation experiments were also fulfilled. Results showed that EK is a viable method for the remediation of these contaminants, both through mobilization by electroosmotic flow (EOF) and electrodegradation. As EOF is very sensible to soil pH, the control in the anolyte increased EOF rate, consequently enhancing contaminants mobilization towards the cathode end. The extent of the mobilization towards the electrode end was mainly dependent on compounds solubility and octanol-water partition coefficient. In the last 24h of experiments, BPA presented the highest mobilization rate (ca. 4 μg min(-1)) with NP not being detected in the catholyte. At the end of all experiments the percentage of contaminants that remained in the soil ranged between 17 and 50 for S2, and between 27 and 48 for S3, with no statistical differences between treatments. The mass balance performed showed that the amount of contaminant not detected in the cell is similar to the quantity that potentially may suffer photo and electrodegradation. PMID:24997283

  3. Simultaneous removal of organic contaminants and heavy metals from kaolin using an upward electrokinetic soil remediation process.

    PubMed

    Wang, Jing-Yuan; Huang, Xiang-Jun; Kao, Jimmy C M; Stabnikova, Olena

    2007-06-01

    Kaolins contaminated with heavy metals, Cu and Pb, and organic compounds, p-xylene and phenanthrene, were treated with an upward electrokinetic soil remediation (UESR) process. The effects of current density, cathode chamber flushing fluid, treatment duration, reactor size, and the type of contaminants under the vertical non-uniform electric field of UESR on the simultaneous removal of the heavy metals and organic contaminants were studied. The removal efficiencies of p-xylene and phenanthrene were higher in the experiments with cells of smaller diameter or larger height, and with distilled water flow in the cathode chamber. The removal efficiency of Cu and Pb were higher in the experiments with smaller diameter or shorter height cells and 0.01M HNO(3) solution as cathode chamber flow. In spite of different conditions for removal of heavy metals and organics, it is possible to use the upward electrokinetic soil remediation process for their simultaneous removal. Thus, in the experiments with duration of 6 days removal efficiencies of phenanthrene, p-xylene, Cu and Pb were 67%, 93%, 62% and 35%, respectively. The experiment demonstrated the feasibility of simultaneous removal of organic contaminants and heavy metals from kaolin using the upward electrokinetic soil remediation process. PMID:17110023

  4. Enhanced electrokinetic extraction of heavy metals from soils assisted by ion exchange membranes.

    PubMed

    Kim, Won-Seok; Kim, Soon-Oh; Kim, Kyoung-Woong

    2005-02-14

    The potential of electrokinetic remediation technology has been successfully demonstrated for the remediation of heavy metal contaminated fine-grained soils through laboratory scale and field application studies. Various enhancement techniques have been proposed and used in order to further improve the remediation process. However, it has been reported that such enhancement schemes can create other obstacles, such as the introduction of non-target ions into the system and thereby decrease the efficiency of the remediation process. Electrokinetic soil remediation technology enhanced by an ion exchange membrane (IEM), IEM-enhanced EK processing, was experimentally evaluated for the purpose of overcoming these obstacles. In particular, this study focused on observations of a fouling problem and its settlement using an auxiliary solution cell (ASC). In addition, the efficacies of two different types of electrode configurations, rectangular and cylindrical, were investigated. The experimental results indicate that the effectiveness of the technology was increased by an enhancement scheme using an IEM. This may be explained by the prevention of metal precipitation in the region near the cathode originating from hydroxide ions generated by the electrolysis of water in the cathode. The experimental results also imply that placement of the ASC can nullify the fouling problem within the cation exchange membranes used in IEM-enhanced EK processing, and thus improve the overall effectiveness of the process. The experimental results indicate that the cylindrical electrode configuration can be implemented in practical situations to improve the treatability of cathode effluent containing a high level of contaminants after processing. PMID:15721533

  5. Combined liquid and gas chromatographic characterisation of polyglycerol fatty acid esters.

    PubMed

    De Meulenaer, B; Van Royen, G; Vanhoutte, B; Huyghebaert, A

    2000-10-27

    In the present study a combined liquid and gas chromatographic technique is described for the analysis of polyglycerol fatty acid esters. Liquid chromatographic fractionation of samples resulted in pure standards of monoesters of di- and triglycerols and diesters of di- and triglycerols. Confirmation of their identity was achieved by LC-MS analysis. Moreover, a chromatographic identification of the mono- and diesters of cyclic diglycerol was proposed. From the isolation of pure esters and their gas chromatographic analysis, it was revealed that co-elution of several compounds occurred. Thus it was shown that prefractionation of the sample using a simplified liquid chromatographic separation, was necessary in order to characterise the esters correctly. In combination with some other chemical analyses, a complete profile of the chemical composition of polyglycerol fatty acid esters can be obtained.

  6. Reversed-phase high-performance liquid chromatographic determination of enoxacin and 4-oxo-enoxacin in human plasma and prostatic tissue. Application to a pharmacokinetic study.

    PubMed

    Hamel, B; Audran, M; Costa, P; Bressolle, F

    1998-07-01

    A simple high-performance liquid chromatographic method has been developed for the simultaneous determination of enoxacin and 4-oxo-enoxacin in plasma and prostatic tissue. The work-up procedure involves a liquid-liquid extraction step followed by isocratic chromatography on a reversed-phase analytical column, with ultraviolet absorbance detection (lambda = 340 nm). Using a mobile phase of 20.9% (v/v) acetonitrile buffer (pH 2.1), adequate retention time and separation among the analytes has been obtained using tetrabutylammonium hydroxide included in the eluent. Retention times are 5.2 min for enoxacin, 6.8 min for pefloxacin and 12 min for 4-oxo-enoxacin. For plasma and prostatic tissue, the precision of the assay was below 9%. The percent recovery from the nominal values for accuracy ranged from 94 to 108%. The limits of quantitation were 20 ng/ml for plasma and 50 ng/g for tissue (precision < 18%). The detection limits were 10 ng/ml and 25 ng/g, respectively. The calibration curves were linear from 20 to 1000 ng/ml for plasma and from 50 to 2500 ng/g for tissue. In plasma, the extraction recoveries averaged 52% for enoxacin and 63% for 4-oxo-enoxacin. In prostatic tissue, they were 57 and 76% for the two analytes, respectively. This method has been employed for the determination of enoxacin and 4-oxo-enoxacin in plasma and prostatic tissue samples from patients following repeated oral administration of enoxacin (400 mg twice a day for four days).

  7. FTIR gas chromatographic analysis of perfumes

    NASA Astrophysics Data System (ADS)

    Diederich, H.; Stout, Phillip J.; Hill, Stephen L.; Krishnan, K.

    1992-03-01

    Perfumes, natural or synthetic, are complex mixtures consisting of numerous components. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques have been extensively utilized for the analysis of perfumes and essential oils. A limited number of perfume samples have also been analyzed by FT-IR gas chromatographic (GC-FTIR) techniques. Most of the latter studies have been performed using the conventional light pipe (LP) based GC-FTIR systems. In recent years, cold-trapping (in a matrix or neat) GC-FTIR systems have become available. The cold-trapping systems are capable of sub-nanogram sensitivities. In this paper, comparison data between the LP and the neat cold-trapping GC- FTIR systems is presented. The neat cold-trapping interface is known as Tracer. The results of GC-FTIR analysis of some commercial perfumes is also presented. For comparison of LP and Tracer GC-FTIR systems, a reference (synthetic) mixture containing 16 major and numerous minor constituents was used. The components of the mixture are the compounds commonly encountered in commercial perfumes. The GC-FTIR spectra of the reference mixture was obtained under identical chromatographic conditions from an LP and a Tracer system. A comparison of the two sets of data thus generated do indeed show the enhanced sensitivity level of the Tracer system. The comparison also shows that some of the major components detected by the Tracer system were absent from the LP data. Closer examination reveals that these compounds undergo thermal decomposition on contact with the hot gold surface that is part of the LP system. GC-FTIR data were obtained for three commercial perfume samples. The major components of these samples could easily be identified by spectra search against a digitized spectral library created using the Tracer data from the reference mixture.

  8. Computational modeling of electrokinetic transport in random networks of micro-pores and nano-pores

    NASA Astrophysics Data System (ADS)

    Alizadeh, Shima; Mani, Ali

    2014-11-01

    A reduced order model has been developed to study the nonlinear electrokinetic behaviors emerging in the transport of ionic species through micro-scale and nano-scale porous media. In this approach a porous structure is modeled as a network of long and thin pores. By assuming transport equilibrium in the thin dimensions for each pore, a 1D transport equation is developed in the longitudinal direction covering a wide range of conditions including extreme limits of thick and thin electric double layers. This 1D model includes transport via diffusion, electromigration and wide range of advection mechanisms including pressure driven flow, electroosmosis, and diffusion osmosis. The area-averaged equations governing the axial transport from different pores are coupled at the pore intersections using the proper conservation laws. Moreover, an asymptotic treatment has been included in order to remove singularities in the limit of small concentration. The proposed method provides an efficient framework for insightful simulations of porous electrokinetic systems with applications in water desalination and energy storage. PhD student in Mechanical Engineering, Stanford University. She received her Master's degree in Mechanical Engineering from Stanford at 2013. Her research interests include CFD, high performance computing, and optimization.

  9. Capillary electrokinetic separations with optical detection. Technical progress report, February 1, 1993--January 31, 1994

    SciTech Connect

    Sepaniak, M.J.

    1993-10-01

    This program seeks the development of capillary electrokinetic separation techniques and associated optical methods of detection. Fundamental studies of pertinent separation and band broadening mechanisms are being conducted, with the emphasis on understanding systems that include highly-ordered assemblies as running buffer additives. The additives include cyclodextrins, affinity reagents, and soluble (entangled) polymers and are employed with capillary electrophoresis, CE and/or micellar electrokinetic capillary chromatography, MECC modes of separation. The utility of molecular modeling techniques for predicting the effects of highly ordered assemblies on the retention behavior of isomeric compounds is under investigation. The feasibility of performing separations using a non-aqueous solvent/fullerene electrochromatographic system is being explored. The analytical methodologies associated with these capillary separation techniques are being advanced through the development of retention programming instumentation/techniques and new strategies for performing optical detection. The advantages of laser fluorimetry are extended through the inclusion of fluorogenic, reagents in the running buffer. These reagents include oligonucleotide intercalation reagents for detecting DNA fragments. Chemiluminescence detection using post-capillary reactors/flow cells is also in progress. Successful development of these separation and detection systems will fill current voids in the capabilities of capillary separation techniques.

  10. Removal of Cr(VI) from contaminated soil by electrokinetic remediation.

    PubMed

    Sawada, Akira; Mori, Ko-ichi; Tanaka, Shunitz; Fukushima, Masami; Tatsumi, Kenji

    2004-01-01

    A new process for the removal of hexavalent chromium [Cr(VI)] contaminated soil is described. The process provides for an efficient removal of anionic chemicals from contaminated soils. Chromate anions were removed from the soil to the anodic reservoir by the moving force of electromigration. In this process, the chromate anions that accumulate in the anodic reservoir are simultaneously eliminated by using a column packed adsorbent. The adsorbent (immobilized tannin) used was chemically incorporated into cellulose. Cr(VI) was found to be adsorbed to this adsorbent efficiently. In the electrokinetic process, the pH of the aqueous solution in the anodic reservoir was decreased by the electrolysis of water. In the present study, the pH of the solution in the anodic reservoir is maintained at pH 6 by the addition of an aqueous alkaline solution during the electrokinetic process. The advantage of pH control is that it promotes the release of Cr(VI) from the soil by electromigration, thus permitting the maximum adsorption of Cr(VI) on the immobilized tannin. Simultaneous collection of Cr(VI) from the anodic reservoir leads to the protection from secondary contamination with Cr(VI).

  11. Analysis of rotation-driven electrokinetic flow in microscale gap regions of rotating disk systems.

    PubMed

    Soong, C Y; Wang, S H

    2004-01-15

    In the present study, a novel theoretical model is developed for the analysis of rotating thermal-fluid flow characteristics in the presence of electrokinetic effects in the microscale gap region between two parallel disks under specified electrostatic, rotational, and thermal boundary conditions. The major flow configuration considered is a rotor-stator disk system. Axisymmetric Navier-Stokes equations with consideration of electric body force stemming from streaming potential are employed in the momentum balance. Variations of the fluid viscosity and permittivity with the local fluid temperature are considered. Between two disks, the axial distribution of the electric potential is determined by the Poisson equation with the concentration distributions of positive and negative ions obtained from Nernst-Planck equations for convection-diffusion of the ions in the flow field. Effects of disk rotation and electrostatic and thermal conditions on the electrokinetic flow and thermal characteristics are investigated. The electrohydrodynamic mechanisms are addressed with an interpretation of the coupling nature of the electric and flow fields. Finally, solutions with electric potential determined by employing nonlinear or linearized Poisson-Boltzmann equation and/or invoking assumptions of constant properties are compared with the predictions of the present model for justification of various levels of approximation in solution of the electrothermal flow behaviors in rotating microfluidic systems. PMID:14654411

  12. Removal of PAHs and pesticides from polluted soils by enhanced electrokinetic-Fenton treatment.

    PubMed

    Bocos, Elvira; Fernández-Costas, Carmen; Pazos, Marta; Sanromán, M Ángeles

    2015-04-01

    In this study, electrokinetic-Fenton treatment was used to remediate a soil polluted with PAHs and the pesticide pyrimethanil. Recently, this treatment has emerged as an interesting alternative to conventional soil treatments due to its peculiar advantages, namely the capability of treating fine and low-permeability materials, as well as that of achieving a high yield in the removals of salt content and inorganic and organic pollutants. In a standard electrokinetic-Fenton treatment, the maximum degradation of the pollutant load achieved was 67%, due to the precipitation of the metals near the cathode chamber that reduces the electro-osmotic flow of the system and thus the efficiency of the treatment. To overcome this problem, different complexing agents and pH control in the cathode chamber were evaluated to increase the electro-osmotic flux as well as to render easier the solubilization of the metal species present in the soil. Four complexing agents (ascorbic acid, citric acid, oxalic acid and ethylenediaminetetraacetic acid) in the Fenton-like treatment were evaluated. Results revealed the citric acid as the most suitable complexing agent. Thereby its efficiency was tested as pH controller by flushing it in the cathode chamber (pH 2 and 5). For the latter treatments, near total degradation was achieved after 27 d. Finally, phytotoxicity tests for polluted and treated samples were carried out. The high germination levels of the soil treated under enhanced conditions concluded that nearly complete restoration was achieved. PMID:25577698

  13. Dynamic and electrokinetic behavior of erythrocyte membrane in diabetes mellitus and diabetic cardiovascular disease.

    PubMed

    Adak, Sangeeta; Chowdhury, Subhankar; Bhattacharyya, Maitree

    2008-02-01

    The dynamic and electrokinetic properties of erythrocyte membrane are explored as significant indices involved in the association of diabetes and diabetic cardiovascular disease. Lipid peroxidation studies reveal malondialdehyde concentration to reach a maximum in diabetic cardiovascular patients. Lower fluidity of erythrocyte membrane implies declined ability of erythrocyte to deform in pathogenic state, which is supported by decreased osmotic resistance. Membrane protein profile modification detected by Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) indicates a significant reduction in the quantity of ankyrin protein band 2.1 in diabetic subjects. In addition the reduction in an immunoreactive band against polyclonal anti-ankyrin antibody during Western blot analysis confirms the modification of ankyrin protein in diseased erythrocyte (reported for the first time). The electrokinetic behavior of erythrocyte membrane is monitored by laser Doppler velocimetry mode of the Nano-ZS. Changes in zeta potential values of the red blood cell membrane are consistent with decreased membrane fluidity in diseased erythrocytes (reported for the first time). Membrane potential values of control, diabetic and diabetic cardiovascular erythrocytes are -37.24+/-1.5 mV, -28.44+/-1.34 mV, and -22.21+/-1.21 mV respectively indicating a gradual lowering of zeta potential when erythrocyte membrane undergoes progressive changes - from simple agglomeration to fluid gel formation - and finally to a rigid gel.

  14. Removal of PAHs and pesticides from polluted soils by enhanced electrokinetic-Fenton treatment.

    PubMed

    Bocos, Elvira; Fernández-Costas, Carmen; Pazos, Marta; Sanromán, M Ángeles

    2015-04-01

    In this study, electrokinetic-Fenton treatment was used to remediate a soil polluted with PAHs and the pesticide pyrimethanil. Recently, this treatment has emerged as an interesting alternative to conventional soil treatments due to its peculiar advantages, namely the capability of treating fine and low-permeability materials, as well as that of achieving a high yield in the removals of salt content and inorganic and organic pollutants. In a standard electrokinetic-Fenton treatment, the maximum degradation of the pollutant load achieved was 67%, due to the precipitation of the metals near the cathode chamber that reduces the electro-osmotic flow of the system and thus the efficiency of the treatment. To overcome this problem, different complexing agents and pH control in the cathode chamber were evaluated to increase the electro-osmotic flux as well as to render easier the solubilization of the metal species present in the soil. Four complexing agents (ascorbic acid, citric acid, oxalic acid and ethylenediaminetetraacetic acid) in the Fenton-like treatment were evaluated. Results revealed the citric acid as the most suitable complexing agent. Thereby its efficiency was tested as pH controller by flushing it in the cathode chamber (pH 2 and 5). For the latter treatments, near total degradation was achieved after 27 d. Finally, phytotoxicity tests for polluted and treated samples were carried out. The high germination levels of the soil treated under enhanced conditions concluded that nearly complete restoration was achieved.

  15. Surface properties of coal fines in water. 1. Electrokinetics and surfactant adsorption

    SciTech Connect

    Ayub, A.L.; Al Taweel, A.M.; Kwak, J.C.T.

    1985-01-01

    The adsorption of phenol, p-nitrophenol, the nonionic surfactant Triton X-100 (a commercial mixture of octylphenol poly ethoxylates) and the cationic surfactant dodecyltrimethyl ammonium bromide (DTAB) from aqueous solution on coal fines from a coal washing plant has been studied. Adsorbate solution concentrations range from 0-8 x 10/sup -4/ m. For the cationic and nonionic surfactants both adsorption isotherms and electrokinetic isotherms were determined. The adsorption of phenol, but not of Triton X-100 and DTAB, is found to increase with time for periods up to three hundred h. For short contract times (less than thirty h.), the amount of Triton X-100 adsorbed is about three times higher than the amount of phenol adsorbed at the same solution concentration. The electrokinetic data show that the zeta potential of the coal is not affected by the adsorption of Triton X-100. On the other hand, adsorption of the cationic surfactant strongly influences the zeta potential. For negatively charged coal, i.e., at higher solution pH (iep of the coal used is 5.3), the adsorption of cationic surfactant leads to charge reversal at a typical free surfactant concentration often well below 10/sup -4/ molal. 20 references.

  16. Monolayers of poly-L-lysine on mica--Electrokinetic characteristics.

    PubMed

    Morga, Maria; Adamczyk, Zbigniew; Gödrich, Sebastian; Oćwieja, Magdalena; Papastavrou, Georg

    2015-10-15

    Physicochemical properties of poly-l-lysine and its monolayers on mica were thoroughly investigated by dynamic light scattering, electrokinetic methods and atomic force microscopy. The hydrodynamic diameter of PLL was equal to 25.5 nm within a wide range of pH and ionic strength. The electrophoretic measurements revealed that the molecules are positively charged for pH<10.5. By exploiting the electrophoretic mobility data, theelectrokinetic charge on the PLL molecules and their zeta potential were calculated. PLL monolayers of controlled coverage were deposited on mica under diffusion-controlled conditions by varying PLL bulk concentration and adsorption time. The electrokinetic characteristics of the monolayers were acquired in situ via streaming potential measurements. These studies allowed to uniquely determine the zeta potential of the monolayers as a function of pH and ionic strength. In this way the isoelectric point of the monolayers can be determined in a more convenient way compared to bulk measurements disturbed by the PLL molecule interactions. The stability of the monolayers under flow conditions was quantitatively evaluated via streaming potential measurements. The adsorption constant and the binding energy depth of PLL molecules were determined for different ionic strengths. These parameters indicate that the PLL monolayers remain stable over prolonged times.

  17. Moisture content-affected electrokinetic remediation of Cr(VI)-contaminated clay by a hydrocalumite barrier.

    PubMed

    Xu, Yunfeng; Xu, Xiangjian; Hou, Hetian; Zhang, Jia; Zhang, Dayi; Qian, Guangren

    2016-04-01

    An electrokinetic-permeable reaction barrier (EK-PRB) system was introduced in this study with hydrocalumite as the barrier material. The combined system effectively remediated the Cr(VI)-contaminated clay after a 72-h treatment, and the Cr(VI) removal efficiency increased with the initial soil moisture content. Further evidence was found that the changing soil pH value and current density were highly associated with the initial moisture content, showing its important roles in the Cr(VI) removal process. Additionally, the total Cr removal efficiency was much lower than that of Cr(VI) owing to the partial conversion of Cr(VI) to Cr(III) in the electrokinetic remediation process. Under high soil moisture conditions (40%), the removal efficiency of Cr(VI) and total Cr was 96.6 and 67.3%, respectively. Further analysis also revealed the new mineral phase, chromate hydrocalumite, for Cr fixation in the hydrocalumite barrier, which was significantly affected by the initial soil moisture content. Our results showed that the EK-PRB system with a hydrocalumite barrier is highly promising with great potential for the effective remediation of Cr(VI)-contaminated clay and engineering implementation. PMID:26635219

  18. On-chip Micro- and Nanofluidic Electrokinetic Injection and Separation for PEGylation Analysis

    NASA Astrophysics Data System (ADS)

    Shelton, Elijah; Baum, Mary; Morse, Dan; Pennathur, Sumita; Pennathur Nanofluidics Laboratory Collaboration; Morse Laboratory Collaboration

    2012-11-01

    We present an experimental study of micro- and nanofluidic electrokinetic injection and separation in borosilcate channels as a method for characterizing size and zeta potential of biomolecules-specifically polyethlylene glycol (PEG), keyhole limpet hemocyanine (KLH), and pegylated KLH. While pegylation (the conjugation of proteins with PEG) is an established technique for enhancing a protein's therapeutic properties, reliable characterization of these conjugations by traditional analysis techniques (i.e. gel-electrophoresis, zetasizer) remains a challenge. Using a three-step electrokinetic sequence (load, gate, and inject), FITC labeled species and a fluorescein tracer dye are injected into a channel where they separate according to differences in electrophoretic mobility. We find the average absolute mobility of pegylated subunit KLH in 1 micron channels to be 56% that of unpegylated subunit KLH. In a 250 nm channel, we measure a 33% shift in the average absolute mobility of PEG dendrimers as compared to measurements in a 1 micron channel. These results begin to demonstrate how a micro- and nanofluidic-based approach might address the demand for effective and accessible nanoparticle characterization platforms. Supported by the Institute for Collaborative Biotechnologies.

  19. Application of response function methodology for the simultaneous determination of potential fragrance allergens and preservatives in personal care products using micellar electrokinetic chromatography.

    PubMed

    Lopez-Gazpio, J; Garcia-Arrona, R; Millán, E

    2014-01-01

    A micellar electrokinetic chromatography method was developed for determination of 15 suspected fragrance allergens and preservatives. The target compounds are widely used as ingredients in many personal care products, and all of them are included in the European Regulation concerning cosmetic products. The method was optimized by using a central composite experimental design and response surface methodology. A modified chromatographic response function was defined to weigh the terms in the response function adequately. After optimization of experimental conditions, a background electrolyte of 100 mM sodium dodecyl sulphate and 24 mM sodium tetraborate and pH 9.0 was selected for the separation of the analytes. The developed methodology was evaluated in terms of linearity, limits of detection and quantification, precision and accuracy, showing appropriate values (i.e., R (2) = ≥0.99 and accuracy of 89-115 %). Finally, applicability of the micellar electrokinetic chromatography method was assessed by successfully quantifying fragrance allergens and preservatives in commercial personal care products. The most commonly found analyte was linalool (48.3 % of samples) followed by benzoic acid (37.6 %). All samples contained at least one of the target compounds, thus confirming the ubiquity of fragrance allergens and preservatives in personal care products.

  20. UPLC and LC-MS studies on degradation behavior of irinotecan hydrochloride and development of a validated stability-indicating ultra-performance liquid chromatographic method for determination of irinotecan hydrochloride and its impurities in pharmaceutical dosage forms.

    PubMed

    Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Sunil P

    2012-10-01

    The objective of the current investigation was to study the degradation behavior of irinotecan hydrochloride under different International Conference on Harmonization (ICH) recommended stress conditions using ultra-performance liquid chromatography and liquid chromatography-mass spectrometry and to establish a validated stability-indicating reverse-phase ultra-performance liquid chromatographic method for the quantitative determination of irinotecan hydrochloride and its seven impurities and degradation products in pharmaceutical dosage forms. Irinotecan hydrochloride was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Irinotecan hydrochloride was found to degrade significantly in oxidative and base hydrolysis and photolytic degradation conditions. The degradation products were well resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. Chromatographic separation was achieved on a Waters Acquity BEH C8 (100 × 2.1 mm) 1.7-µm column with a mobile phase containing a gradient mixture of solvent A (0.02M KH(2)PO(4) buffer, pH 3.4) and solvent B (a mixture of acetonitrile and methanol in the ratio of 62:38 v/v). The mobile phase was delivered at a flow rate of 0.3 mL/min with ultraviolet detection at 220 nm. The run time was 8 min, within which irinotecan and its seven impurities and degradation products were satisfactorily separated. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of irinotecan hydrochloride in pharmaceutical dosage forms.

  1. An open tubular ion chromatograph.

    PubMed

    Yang, Bingcheng; Zhang, Min; Kanyanee, Tinakorn; Stamos, Brian N; Dasgupta, Purnendu K

    2014-12-01

    We describe an open tubular ion chromatograph (OTIC) that uses anion exchange latex coated 5 μm radius silica and 9.8 μm radius poly(methyl methacrylate) tubes and automated time/pressure based hydrodynamic injection for pL-nL scale injections. It is routinely possible to generate 50,000 plates or more (up to 150,000 plates/m, columns between 0.3 and 0.8 m have been used), and as such, fast separations are possible, comparable to or in some cases better than the current practice of IC. With an optimized admittance detector, nonsuppressed detection permits LODs of submicromolar to double digit micromolar for a variety of analytes. However, large volume injections are possible and can significantly improve on this. A variety of eluents, the use of organic modifiers, and variations of eluent pH can be used to tailor a given separation. The approach is discussed in the context of extraterrestrial exploration, especially Mars, where the existence of large amounts of perchlorate in the soil needs to be confirmed. These columns can survive drying and freezing, and small footprint, low power consumption, and simplicity make OTIC a good candidate for such a mission. PMID:25394230

  2. Joule Heating Effects on Electrokinetic Flow Instabilities in Ferrofluids

    NASA Astrophysics Data System (ADS)

    Brumme, Christian; Shaw, Ryan; Zhou, Yilong; Prabhakaran, Rama; Xuan, Xiangchun

    We have demonstrated in our earlier work that the application of a tangential electric field can draw fluid instabilities at the interface of a ferrofluid/water co-flow. These electrokinetic flow instabilities are produced primarily by the mismatch of electric conductivities of the two fluids. We demonstrate in this talk that the Joule heating induced fluid temperature rises and gradients can significantly suppress the electrokinetic flow instabilities. We also develop a two-dimensional depth-averaged numerical model to predict the fluid temperature, flow and concentration fields in the two-fluid system with the goal to understand the Joule heating effects on electric field-driven ferrofluid flow instabilities. This work was supported by the Honors and Creative Inquiry programs at Clemson University.

  3. Microfabricated porous glass channels for electrokinetic separation devices.

    PubMed

    Cezar de Andrade Costa, Reges; Mogensen, Klaus Bo; Kutter, Jörg Peter

    2005-11-01

    Electrically insulated porous SiO2 channels for electrokinetic separation devices were fabricated based on a mask-less etching process for creation of high aspect ratio needles in silicon. The silicon needles are converted to SiO2 by oxidation and integrated within the interior of a fluidic channel network. The channels are about 5 microm high with a pore size of 0.5+/-0.2 microm. An electrophoretic separation of a mixture of fluorescein and 5-carboxyfluorescein using epi-fluorescence detection was performed to verify proper electrokinetic transport in the porous channels. The plate height was about 170,000 m-1 for a field strength of 170 V cm-1. In the near future, it is intended to extend the fabrication scheme to include an array of porous pillars for capillary electrochromatography experiments. PMID:16234957

  4. Cast-to-shape electrokinetic trapping medium

    SciTech Connect

    Shepodd, Timothy J.; Franklin, Elizabeth; Prickett, Zane T.; Artau, Alexander

    2004-08-03

    A three-dimensional microporous polymer network material, or monolith, cast-to-shape in a microchannel. The polymer monolith, produced by a phase separation process, is capable of trapping and retaining charged protein species from a mixture of charged and uncharged species under the influence of an applied electric field. The retained charged protein species are released from the porous polymer monolith by a pressure driven flow in the substantial absence of the electric field. The pressure driven flow is independent of direction and thus neither means to reverse fluid flow nor a multi-directional flow field is required, a single flow through the porous polymer monolith can be employed, in contrast to prior art systems. The monolithic polymer material produced by the invention can function as a chromatographic medium. Moreover, by virtue of its ability to retain charged protein species and quantitatively release the retained species the porous polymer monolith can serve as a means for concentrating charged protein species from, for example, a dilute solution.

  5. Cast-to-shape electrokinetic trapping medium

    SciTech Connect

    Shepodd, Timothy J.; Franklin, Elizabeth; Prickett, Zane T.; Artau, Alexander

    2006-05-30

    A three-dimensional microporous polymer network material, or monolith, cast-to-shape in a microchannel. The polymer monolith, produced by a phase separation process, is capable of trapping and retaining charged protein species from a mixture of charged and uncharged species under the influence of an applied electric field. The retained charged protein species are released from the porous polymer monolith by a pressure driven flow in the substantial absence of the electric field. The pressure driven flow is independent of direction and thus neither means to reverse fluid flow nor a multi-directional flow field is required, a single flow through the porous polymer monolith can be employed, in contrast to prior art systems. The monolithic polymer material produced by the invention can function as a chromatographic medium. Moreover, by virtue of its ability to retain charged protein species and quantitatively release the retained species the porous polymer monolith can serve as a means for concentrating charged protein species from, for example, a dilute solution.

  6. A Quantitative Gas Chromatographic Ethanol Determination.

    ERIC Educational Resources Information Center

    Leary, James J.

    1983-01-01

    Describes a gas chromatographic experiment for the quantitative determination of volume percent ethanol in water ethanol solutions. Background information, procedures, and typical results are included. Accuracy and precision of results are both on the order of two percent. (JN)

  7. Gas Chromatographic Determination of Enrivonmentally Significant Pesticides.

    ERIC Educational Resources Information Center

    Rudzinski, Walter E.; Beu, Steve

    1982-01-01

    A chromatographic procedure for analyzing organophosphorus pesticides (such as PCB's, nitrosamines, and phthalate esters) in orange juice is described, including a summary of the method, instrumentation, methodology, results/discussion, and calculations. (JN)

  8. A Versatile, Automatic Chromatographic Column Packing Device

    ERIC Educational Resources Information Center

    Barry, Eugene F.; And Others

    1977-01-01

    Describes an inexpensive apparatus for packing liquid and gas chromatographic columns of high efficiency. Consists of stainless steel support struts, an Automat Getriebmotor, and an associated three-pulley system capable of 10, 30, and 300 rpm. (MLH)

  9. Recent applications of AC electrokinetics in biomolecular analysis on microfluidic devices.

    PubMed

    Sasaki, Naoki

    2012-01-01

    AC electrokinetics is a generic term that refers to an induced motion of particles and fluids under nonuniform AC electric fields. The AC electric fields are formed by application of AC voltages to microelectrodes, which can be easily integrated into microfluidic devices by standard microfabrication techniques. Moreover, the magnitude of the motion is large enough to control the mass transfer on the devices. These advantages are attractive for biomolecular analysis on the microfluidic devices, in which the characteristics of small space and microfluidics have been mainly employed. In this review, I describe recent applications of AC electrokinetics in biomolecular analysis on microfluidic devices. The applications include fluid pumping and mixing by AC electrokinetic flow, and manipulation of biomolecules such as DNA and proteins by various AC electrokinetic techniques. Future prospects for highly functional biomolecular analysis on microfluidic devices with the aid of AC electrokinetics are also discussed.

  10. Removal of fluorine from contaminated soil by electrokinetic treatment driven by solar energy.

    PubMed

    Zhou, Ming; Zhu, Shufa; Liu, Yana; Wang, Xuejian

    2013-08-01

    Instead of direct current power supply, a series of electrokinetic remediation experiments driven by solar energy on fluorine-contaminated soil were conducted in a self-made electrolyzer, in order to reduce energy expenditure of electrokinetic remediation. After the 12-day electrokinetic remediation driven by solar energy, the removal efficiency of fluorine was 22.3%, and electrokinetic treatment had an impact on changes in partitioning of fluorine in soil. It proved that the combination of electrokinetics and solar energy was feasible and effective to some extent for the remediation of fluorine-contaminated soil. Meanwhile, the experimental results also indicated that the electromigration was a more dominant transport mechanism for the removal of fluorine from contaminated soil than electroosmosis, and the weather condition was the important factor in affecting the removal efficiency.

  11. Removal of fluorine from contaminated soil by electrokinetic treatment driven by solar energy.

    PubMed

    Zhou, Ming; Zhu, Shufa; Liu, Yana; Wang, Xuejian

    2013-08-01

    Instead of direct current power supply, a series of electrokinetic remediation experiments driven by solar energy on fluorine-contaminated soil were conducted in a self-made electrolyzer, in order to reduce energy expenditure of electrokinetic remediation. After the 12-day electrokinetic remediation driven by solar energy, the removal efficiency of fluorine was 22.3%, and electrokinetic treatment had an impact on changes in partitioning of fluorine in soil. It proved that the combination of electrokinetics and solar energy was feasible and effective to some extent for the remediation of fluorine-contaminated soil. Meanwhile, the experimental results also indicated that the electromigration was a more dominant transport mechanism for the removal of fluorine from contaminated soil than electroosmosis, and the weather condition was the important factor in affecting the removal efficiency. PMID:23475445

  12. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    SciTech Connect

    Liu, Ying

    2004-01-01

    My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were able to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic

  13. Chromatographic and computational assessment of lipophilicity using sum of ranking differences and generalized pair-correlation.

    PubMed

    Andrić, Filip; Héberger, Károly

    2015-02-01

    Lipophilicity (logP) represents one of the most studied and most frequently used fundamental physicochemical properties. At present there are several possibilities for its quantitative expression and many of them stems from chromatographic experiments. Numerous attempts have been made to compare different computational methods, chromatographic methods vs. computational approaches, as well as chromatographic methods and direct shake-flask procedure without definite results or these findings are not accepted generally. In the present work numerous chromatographically derived lipophilicity measures in combination with diverse computational methods were ranked and clustered using the novel variable discrimination and ranking approaches based on the sum of ranking differences and the generalized pair correlation method. Available literature logP data measured on HILIC, and classical reversed-phase combining different classes of compounds have been compared with most frequently used multivariate data analysis techniques (principal component and hierarchical cluster analysis) as well as with the conclusions in the original sources. Chromatographic lipophilicity measures obtained under typical reversed-phase conditions outperform the majority of computationally estimated logPs. Oppositely, in the case of HILIC none of the many proposed chromatographic indices overcomes any of the computationally assessed logPs. Only two of them (logkmin and kmin) may be selected as recommended chromatographic lipophilicity measures. Both ranking approaches, sum of ranking differences and generalized pair correlation method, although based on different backgrounds, provides highly similar variable ordering and grouping leading to the same conclusions.

  14. Optimisation of n-Hexyl Acetate Synthesis in a Chromatographic Reactor

    NASA Astrophysics Data System (ADS)

    Patel, Dipesh; Saha, Basudeb; Wakeman, Richard

    Laboratory scale batch chromatographic reactor experiments were carried for the esterification of acetic acid with n-hexanol to synthesise a value added ester, namely n-hexyl acetate in the presence of an ion exchange resin catalyst, Purolite CT-124. The effect of various parameters such as solvent flow rates in the regeneration step, amount of reactants in the reaction step and reaction step time was studied for optimisation of the reaction condition in a batch chromatographic reactor. This information would be useful for the design, operation and optimisation of n-hexyl acetate synthesis in a continuous chromatographic reactor.

  15. Anti-Brownian ELectrokinetic (ABEL) Trapping of Single High Density Lipoprotein (HDL) Particles

    NASA Astrophysics Data System (ADS)

    Bockenhauer, Samuel; Furstenberg, Alexandre; Wang, Quan; Devree, Brian; Jie Yao, Xiao; Bokoch, Michael; Kobilka, Brian; Sunahara, Roger; Moerner, W. E.

    2010-03-01

    The ABEL trap is a novel device for trapping single biomolecules in solution for extended observation. The trap estimates the position of a fluorescently-labeled object as small as ˜10 nm in solution and then applies a feedback electrokinetic drift every 20 us to trap the object by canceling its Brownian motion. We use the ABEL trap to study HDL particles at the single-copy level. HDL particles, essential in regulation of ``good'' cholesterol in humans, comprise a small (˜10 nm) lipid bilayer disc bounded by a belt of apolipoproteins. By engineering HDL particles with single fluorescent donor/acceptor probes and varying lipid compositions, we are working to study lipid diffusion on small length scales. We also use HDL particles as hosts for single transmembrane receptors, which should enable study of receptor conformational dynamics on long timescales.

  16. Electrokinetic remediation and microbial community shift of β-cyclodextrin-dissolved petroleum hydrocarbon-contaminated soil.

    PubMed

    Wan, Chunli; Du, Maoan; Lee, Duu-Jong; Yang, Xue; Ma, Wencheng; Zheng, Lina

    2011-03-01

    Electrokinetic (EK) migration of β-cyclodextrin (β-CD), which is inclusive of total petroleum hydrocarbon (TPH), is an economically beneficial and environmentally friendly remediation process for oil-contaminated soils. Remediation studies of oil-contaminated soils generally prepared samples using particular TPHs. This study investigates the removal of TPHs from, and electromigration of microbial cells in field samples via EK remediation. Both TPH content and soil respiration declined after the EK remediation process. The strains in the original soil sample included Bacillus sp., Sporosarcina sp., Beta proteobacterium, Streptomyces sp., Pontibacter sp., Azorhizobium sp., Taxeobacter sp., and Williamsia sp. Electromigration of microbial cells reduced the biodiversity of the microbial community in soil following EK remediation. At 200 V m(-1) for 10 days, 36% TPH was removed, with a small population of microbial cells flushed out, demonstrating that EK remediation is effective for the present oil-contaminated soils collected in field.

  17. Electrokinetic remediation and microbial community shift of β-cyclodextrin-dissolved petroleum hydrocarbon-contaminated soil.

    PubMed

    Wan, Chunli; Du, Maoan; Lee, Duu-Jong; Yang, Xue; Ma, Wencheng; Zheng, Lina

    2011-03-01

    Electrokinetic (EK) migration of β-cyclodextrin (β-CD), which is inclusive of total petroleum hydrocarbon (TPH), is an economically beneficial and environmentally friendly remediation process for oil-contaminated soils. Remediation studies of oil-contaminated soils generally prepared samples using particular TPHs. This study investigates the removal of TPHs from, and electromigration of microbial cells in field samples via EK remediation. Both TPH content and soil respiration declined after the EK remediation process. The strains in the original soil sample included Bacillus sp., Sporosarcina sp., Beta proteobacterium, Streptomyces sp., Pontibacter sp., Azorhizobium sp., Taxeobacter sp., and Williamsia sp. Electromigration of microbial cells reduced the biodiversity of the microbial community in soil following EK remediation. At 200 V m(-1) for 10 days, 36% TPH was removed, with a small population of microbial cells flushed out, demonstrating that EK remediation is effective for the present oil-contaminated soils collected in field. PMID:21052991

  18. Toward a Better Understanding of the Seismolectric Logging Wavefields and the Earthquake Coseismic Electrokinetic Signals

    NASA Astrophysics Data System (ADS)

    Hu, H.; Guan, W.; Wang, Z.

    2014-12-01

    Borehole electrokinetic wavefields have been theoretically simulated and experimentally recorded. However, it is still challenging to explain some of the signals in the full seismoeletric waveform. Similarly, while earthquake coseismic electric and magnetic signals were recorded and theoretically modeled, there are some basic questions to be answered regarding the formulation of the earthquake electrokinetic field. First, an electromagnetic signal appears at the same time in all recorded full waveforms when an acoustic wave is incident on the borehole wall or an interface between two porous media. Is it a traveling electromagnetic wave or a field? This is explained by a comparison between the waveforms obtained by solving the full Pride equations and those by a quasi-static approximation to the seismic-to-electric conversion. Second, a magnetic signal accompanies the borehole P-wave. Does that contradicts to Pride's prediction that no magnetic signal travels with a P-wave? We will show that the borehole P-wave consists of plane fast-P, slow-P and shear waves. It is the plane S-wave that brings about the magnetic field. Thirdly, it was proposed that there were no seismoelectric signal accompanying the collar wave during seismoelectric logging while drilling, because the electrokinetic conversion occurs only in the porous formation. Why there is an electric signal accompanies the acoustic collar wave? A detailed study of the acoustic field in the formation reveals that there is a wave propagates with the collar wave speed in the formation. This wave is present in the calculated full waveforms, either by the discrete wavenumber method or by the finite-difference-time-domain algorithm. That explains the existence of a noise signal with collar-wave speed in the full waveform of the electric field recorded during seismoelectric logging while drilling. Finally, an earthquake is usually modeled by a double couple in an elastic medium, and the displacement field is

  19. Optimization and validation of a nonaqueous micellar electrokinetic chromatography method for determination of polycyclic musks in perfumes.

    PubMed

    Lopez-Gazpio, Josu; Garcia-Arrona, Rosa; Ostra, Miren; Millán, Esmeralda

    2012-06-01

    A nonaqueous micellar electrokinetic chromatography method was developed for determination of Tonalide®, Galaxolide®, and Traseolide® polycyclic musks (PCMs). These compounds are widely used as fragrance ingredients in cosmetics. The method was optimized by using a three variable Box-Behnken experimental design and response surface methodology. A modified chromatographic response function was defined in order to adequately weigh the terms in the response function. After optimization of experimental conditions, an electrolyte solution of 195 mM SDS and 40 mM NaH(2) PO(4) in formamide was selected for the separation of the three PCMs, and the applied voltage was fixed at 30 kV. The nonaqueous MEKC method was then checked in terms of linearity, limits of detection and quantification, repeatability, intermediate precision and accuracy, providing appropriate values (i.e. RSD values for precision never exceeding 7%, and accuracy 96-107%). Nonaqueous MEKC for determination of the selected compounds was successfully applied to the analysis of commercial perfume samples.

  20. Portable gas chromatograph-mass spectrometer

    DOEpatents

    Andresen, Brian D.; Eckels, Joel D.; Kimmons, James F.; Myers, David W.

    1996-01-01

    A gas chromatograph-mass spectrometer (GC-MS) for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units.

  1. Portable gas chromatograph-mass spectrometer

    DOEpatents

    Andresen, B.D.; Eckels, J.D.; Kimmons, J.F.; Myers, D.W.

    1996-06-11

    A gas chromatograph-mass spectrometer (GC-MS) is described for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units. 4 figs.

  2. Portable gas chromatograph-mass spectrometer

    SciTech Connect

    Andresen, B.D.; Eckels, J.D.; Kimmins, J.F.; Myers, D.W.

    1994-12-31

    A gas chromatograph-mass spectrometer (GC-MS) for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units.

  3. Electrokinetics for removal of low-level radioactivity from soil

    SciTech Connect

    Pamukcu, S.; Wittle, J.K.

    1993-03-01

    The electrokinetic process is an emerging technology for in situ soil decontamination in which chemical species, both ionic and nonionic, are transported to an electrode site in soil. These products are subsequently removed from the ground via collection systems engineered for each specific application. The work presented here describes part of the effort undertaken to investigate electrokinetically enhanced transport of soil contaminants in synthetic systems. These systems consisted of clay or clay-sand mixtures containing known concentrations of a selected heavy-metal salt solution. These metals included surrogate radionuclides such as Sr, Cs and U, and an anionic species of Cr. Degree of removal of these metals from soil by the electrokinetic treatment process was assessed through the metal concentration profiles generated across the soil between the electrodes. Removals of some metal species up to 99% were achieved at the anode or cathode end of the soil upon 24 to 48 hours of treatment or a maximum of 1 pore volume of water displacement toward the cathode compartment. Transient pH change through the soil had an effect on the metal movement, as evidenced by accumulation of the metals at the discharge ends of the soil specimens. This accumulation was attributed to the precipitation of the metal and increased cation retention capacity of the clay in high pH environment at the cathode end. In general, the reduced mobility and dissociation of the ionic species as they encounter areas of higher ionic concentration in their path of migration resulted in the accumulation of the metals at the discharge ends of the soil specimens.

  4. Electrokinetic-enhanced bioremediation of organic contaminants: a review of processes and environmental applications.

    PubMed

    Gill, R T; Harbottle, M J; Smith, J W N; Thornton, S F

    2014-07-01

    There is current interest in finding sustainable remediation technologies for the removal of contaminants from soil and groundwater. This review focuses on the combination of electrokinetics, the use of an electric potential to move organic and inorganic compounds, or charged particles/organisms in the subsurface independent of hydraulic conductivity; and bioremediation, the destruction of organic contaminants or attenuation of inorganic compounds by the activity of microorganisms in situ or ex situ. The objective of the review is to examine the state of knowledge on electrokinetic bioremediation and critically evaluate factors which affect the up-scaling of laboratory and bench-scale research to field-scale application. It discusses the mechanisms of electrokinetic bioremediation in the subsurface environment at different micro and macroscales, the influence of environmental processes on electrokinetic phenomena and the design options available for application to the field scale. The review also presents results from a modelling exercise to illustrate the effectiveness of electrokinetics on the supply electron acceptors to a plume scale scenario where these are limiting. Current research needs include analysis of electrokinetic bioremediation in more representative environmental settings, such as those in physically heterogeneous systems in order to gain a greater understanding of the controlling mechanisms on both electrokinetics and bioremediation in those scenarios.

  5. Electrokinetic-enhanced bioremediation of organic contaminants: a review of processes and environmental applications.

    PubMed

    Gill, R T; Harbottle, M J; Smith, J W N; Thornton, S F

    2014-07-01

    There is current interest in finding sustainable remediation technologies for the removal of contaminants from soil and groundwater. This review focuses on the combination of electrokinetics, the use of an electric potential to move organic and inorganic compounds, or charged particles/organisms in the subsurface independent of hydraulic conductivity; and bioremediation, the destruction of organic contaminants or attenuation of inorganic compounds by the activity of microorganisms in situ or ex situ. The objective of the review is to examine the state of knowledge on electrokinetic bioremediation and critically evaluate factors which affect the up-scaling of laboratory and bench-scale research to field-scale application. It discusses the mechanisms of electrokinetic bioremediation in the subsurface environment at different micro and macroscales, the influence of environmental processes on electrokinetic phenomena and the design options available for application to the field scale. The review also presents results from a modelling exercise to illustrate the effectiveness of electrokinetics on the supply electron acceptors to a plume scale scenario where these are limiting. Current research needs include analysis of electrokinetic bioremediation in more representative environmental settings, such as those in physically heterogeneous systems in order to gain a greater understanding of the controlling mechanisms on both electrokinetics and bioremediation in those scenarios. PMID:24875868

  6. cDPD: A new dissipative particle dynamics method for modeling electrokinetic phenomena at the mesoscale

    NASA Astrophysics Data System (ADS)

    Deng, Mingge; Li, Zhen; Borodin, Oleg; Karniadakis, George Em

    2016-10-01

    We develop a "charged" dissipative particle dynamics (cDPD) model for simulating mesoscopic electrokinetic phenomena governed by the stochastic Poisson-Nernst-Planck and the Navier-Stokes equations. Specifically, the transport equations of ionic species are incorporated into the DPD framework by introducing extra degrees of freedom and corresponding evolution equations associated with each DPD particle. Diffusion of ionic species driven by the ionic concentration gradient, electrostatic potential gradient, and thermal fluctuations is captured accurately via pairwise fluxes between DPD particles. The electrostatic potential is obtained by solving the Poisson equation on the moving DPD particles iteratively at each time step. For charged surfaces in bounded systems, an effective boundary treatment methodology is developed for imposing both the correct hydrodynamic and electrokinetics boundary conditions in cDPD simulations. To validate the proposed cDPD model and the corresponding boundary conditions, we first study the electrostatic structure in the vicinity of a charged solid surface, i.e., we perform cDPD simulations of the electrostatic double layer and show that our results are in good agreement with the well-known mean-field theoretical solutions. We also simulate the electrostatic structure and capacity densities between charged parallel plates in salt solutions with different salt concentrations. Moreover, we employ the proposed methodology to study the electro-osmotic and electro-osmotic/pressure-driven flows in a micro-channel. In the latter case, we simulate the dilute poly-electrolyte solution drifting by electro-osmotic flow in a micro-channel, hence demonstrating the flexibility and capability of this method in studying complex fluids with electrostatic interactions at the micro- and nano-scales.

  7. Extraction and chromatographic elution behavior of endohedral metallofullerenes: Inferences regarding effective dipole moments

    SciTech Connect

    Fuchs, D.; Rietschel, H.; Michel, R.H.; Fischer, A.; Weis, P.; Kappes, M.M.

    1996-01-11

    Chromatographic retention relationships between Ce-, Gd-, La-, and Y- containing endohedral metallofullerenes and a [2-(1-pyrenyl)ethyl]silyl-silica stationary phase were studied using toluene as eluent. Measurements are discussed in comparison to those of empty fullerenes. Both the extraction and chromatographic elution behaviour of the metallofullerenes reflect their polar nature and allow inferences regarding the presence of a dipole moment in M@C{sub 82}. 55 refs., 4 figs.

  8. Electrokinetic concentration of DNA polymers in nanofluidic channels.

    PubMed

    Stein, Derek; Deurvorst, Zeno; van der Heyden, Frank H J; Koopmans, Wiepke J A; Gabel, Alan; Dekker, Cees

    2010-03-10

    DNA molecules can be concentrated in a narrow region of a nanochannel when driven electrokinetically in submillimolar salt solutions. Transport experiments and theoretical modeling reveal the interplay of electrophoresis, electro-osmosis, and the unique statistical properties of confined polymers that lead to DNA aggregation. A finite conductance through the bulk of the device also plays a crucial role by influencing the electric fields in the nanochannel. We build on this understanding by demonstrating how a nanofluidic device with integrated electrodes can preconcentrate DNA at selected locations and at physiological salt concentrations that are relevant to lab-on-a-chip applications. PMID:20151696

  9. ELECTROKINETIC DENSIFICATION OF COAL FINES IN WASTE PONDS

    SciTech Connect

    E. James Davis

    1999-12-18

    The objective of this research was to demonstrate that electrokinetics can be used to remove colloidal coal and mineral particles from coal-washing ponds and lakes without the addition of chemical additives such as salts and polymeric flocculants. The specific objectives were: Design and develop a scaleable electrophoresis apparatus to clarify suspensions of colloidal coal and clay particles; Demonstrate the separation process using polluted waste water from the coal-washing facilities at the coal-fired power plants in Centralia, WA; Develop a mathematical model of the process to predict the rate of clarification and the suspension electrical properties needed for scale up.

  10. A calibration method for optical trap force by use of electrokinetic phenomena

    NASA Astrophysics Data System (ADS)

    Yu, Youli; Zhang, Zhenxi; Zhang, Xiaolin

    2006-09-01

    An experimental method for calibration of optical trap force upon cells by use of electrokinetic phenomena is demonstrated. An electronkinetic sample chamber system (ESCS) is designed instead of a common sample chamber and a costly automatism stage, thus the experimental setup is simpler and cheaper. Experiments indicate that the range of the trap force measured by this method is piconewton and sub-piconewton, which makes it fit for study on non-damage interaction between light and biological particles with optical tweezers especially. Since this method is relevant to particle electric charge, by applying an alternating electric field, the new method may overcome the problem of correcting drag force and allow us to measure simultaneously optical trap stiffness and particle electric charge.

  11. Capillary electrokinetic separations with optical detection. Technical progress report, February 1, 1994--January 31, 1995

    SciTech Connect

    Sepaniak, M.J.

    1995-05-01

    This multifarious research program is dedicated to the development of capillary electrokinetic separation techniques and associated optical methods of detection. Currently, research is directed at three general objectives. First, fundamental studies of pertinent separation and band broadening mechanisms are being conducted, with the emphasis on achieving rapid separations and understanding separation systems that include highly-ordered assemblies as running buffer additives. Second, instrumentation and methodologies associated with these capillary separation techniques are being advanced. Third, applications of these separation and detection systems should fill current voids in the capabilities of capillary separation techniques. In particular, it should be possible to perform rapid, highly efficient, and selective separations of hydrophobic compounds (e.g., higher MW polycyclic aromatic hydrocarbons (PAHs) and fullerenes), certain optical isomers, DNA fragments, and various pollutants including certain heavy metals.

  12. Self-consistent description of electrokinetic phenomena in particle-based simulations.

    PubMed

    Hernández-Ortiz, Juan P; de Pablo, Juan J

    2015-07-01

    A new computational method is presented for study suspensions of charged particles undergoing fluctuating hydrodynamic and electrostatic interactions. The proposed model is appropriate for polymers, proteins, and porous particles embedded in a continuum electrolyte. A self-consistent Langevin description of the particles is adopted in which hydrodynamic and electrostatic interactions are included through a Green's function formalism. An Ewald-like split is adopted in order to satisfy arbitrary boundary conditions for the Stokeslet and Poisson Green functions, thereby providing a formalism that is applicable to any geometry and that can be extended to deformable objects. The convection-diffusion equation for the continuum ions is solved simultaneously considering Nernst-Planck diffusion. The method can be applied to systems at equilibrium and far from equilibrium. Its applicability is demonstrated in the context of electrokinetic motion, where it is shown that the ionic clouds associated with individual particles can be severely altered by the flow and concentration, leading to intriguing cooperative effects.

  13. On-line micellar electrokinetic chromatography-electrospray ionization mass spectrometry using anodically migrating micelles

    SciTech Connect

    Yang, L.; Harrata, A.K.; Lee, C.S. |

    1997-05-15

    On-line micellar electrokinetic chromatography (MEKC)-electrospray ionization mass spectrometry (ESIMS) is demonstrated for the analysis of chlorotriazine herbicides and barbiturates. In this study, the micellar velocity is directly manipulated by the adjustment of electroosmosis rather than the electrophoretic velocity of the micelle. The electroosmotic flow is adjusted against the electrophoretic velocity of the micelle by changing the solution pH in MEKC. The elimination of MEKC surfactant introduction into ESIMS is achieved with an anodically migrating micelle, moving away from the electrospray interface. The effects of moving surfactant boundary in the MEKC capillary on separation efficiency and resolution of triazine herbicides and barbiturates are investigated. The mass detection of herbicides and barbiturates sequentially eluted from the MEKC capillary is acquired using the positive and negative electrospray modes, respectively. 30 refs., 8 figs., 3 tabs.

  14. AFM characterization of nanobubble formation and slip condition in oxygenated and electrokinetically altered fluids.

    PubMed

    Bhushan, Bharat; Pan, Yunlu; Daniels, Stephanie

    2013-02-15

    Nanobubbles are gas-filled features that spontaneously form at the interface of hydrophobic surfaces and aqueous solutions. In this study, an atomic force microscope (AFM) was used to characterize the morphology of nanobubbles formed on hydrophobic polystyrene (PS) and octadecyltrichlorosilane (OTS) films immersed in DI water, saline, saline with oxygen and an electrokinetically altered saline solution produced with Taylor-Couette-Poiseuille flow under elevated oxygen pressure. AFM force spectroscopy was used to evaluate hydrodynamic and electrostatic forces and boundary slip condition in various fluids. The effect of solution, electric field and surface charge on shape, size and density of nanobubbles as well as slip length was quantified and the results and underlying mechanisms are presented in this paper.

  15. Solute-solvent interactions in micellar electrokinetic chromatography: V. Factors that produce peak splitting.

    PubMed

    Ràfols, Clara; Poza, Ana; Fuguet, Elisabet; Rosés, Martí; Bosch, Elisabeth

    2002-08-01

    The experimental conditions that produce analyte peak splitting in micellar electrokinetic capillary chromatography (MEKC) have been systematically investigated. The system studied was a neutral phosphate buffer and sodium dodecyl sulfate (SDS) micelles as pseudostationary phase. A number of analytes showing a wide variety of hydrophobicity values and several organic solvents as sample diluents have been tested. Peak splitting phenomena are mainly due to the presence of organic solvent in the sample solution. They increase with the hydrophobicity of the analyte and decrease with the increase of the surfactant concentration. When hydrophobic compounds are analyzed the suggested ways to avoid split peaks are: (i) the use of 1-propanol or 1-butanol as sample diluent instead of methanol or acetonitrile or (ii) the use of high concentration of surfactant in the separating solution when the analyte must be dissolved in pure methanol or acetonitrile.

  16. Ion chromatographic determination of sulfur in fuels

    NASA Technical Reports Server (NTRS)

    Mizisin, C. S.; Kuivinen, D. E.; Otterson, D. A.

    1978-01-01

    The sulfur content of fuels was determined using an ion chromatograph to measure the sulfate produced by a modified Parr bomb oxidation. Standard Reference Materials from the National Bureau of Standards, of approximately 0.2 + or - 0.004% sulfur, were analyzed resulting in a standard deviation no greater than 0.008. The ion chromatographic method can be applied to conventional fuels as well as shale-oil derived fuels. Other acid forming elements, such as fluorine, chlorine and nitrogen could be determined at the same time, provided that these elements have reached a suitable ionic state during the oxidation of the fuel.

  17. A sensitive liquid chromatographic-mass spectrometric method for simultaneous quantification of six iridoid glycosides from Zhi-zi-chi Decoction in rat plasma and its application to a pharmacokinetic study.

    PubMed

    Qu, Kankan; Dai, Jinna; Zhao, Longshan; Lu, Yanan; Li, Bin; Zhao, Xu; Hou, Pengyi; Zhang, Yuanting; Bi, Kaishun; Chen, Xiaohui

    2013-05-01

    A sensitive liquid chromatographic-mass spectrometric (LC-MS) method was developed and validated for simultaneous determination of geniposide, geniposidic acid, scandoside methyl ester, gardenoside, deacetyl asperulosidic acid methyl ester and genipin-1-β-gentiobioside after oral administration of Zhi-zi-chi Decoction in rat plasma. The six iridoid glycosides were extracted from plasma samples by protein precipitation, and then separated on an Apollo C18 column (250 mm × 4.6mm, 5 μm) through the application of a gradient elution. The analytes were monitored in positive electrospray ionization by selected ion monitoring mode (SIM). The lower limits of quantitation (LLOQ) of the six analytes were all lower than 6 ng/mL. The accuracy (relative error, RE%) was between -7.0% and 9.9%, while the intra- and inter-day precisions (relative standard deviation, RSD%) were less than 6.3% and 9.8% for the six analytes, respectively. The developed method was successfully applied to a comparative pharmacokinetic study of the six iridoids in rat plasma after oral administration of Zhi-zi-chi Decoction and Gardenia jasminoides extract.

  18. Electro-kinetic remediation coupled with phytoremediation to remove lead, arsenic and cesium from contaminated paddy soil.

    PubMed

    Mao, Xinyu; Han, Fengxiang X; Shao, Xiaohou; Guo, Kai; McComb, Jacqueline; Arslan, Zikri; Zhang, Zhanyu

    2016-03-01

    The objectives of this study were to investigate distribution and solubility of Pb, Cs and As in soils under electrokinetic field and examine the processes of coupled electrokinetic phytoremediation of polluted soils. The elevated bioavailability and bioaccumulation of Pb, As and Cs in paddy soil under an electro-kinetic field (EKF) were studied. The results show that the EKF treatment is effective on lowering soil pH to around 1.5 near the anode which is beneficial for the dissolution of metal(loid)s, thus increasing their overall solubility. The acidification in the anode soil efficiently increased the water soluble (SOL) and exchangeable (EXC) Pb, As and Cs, implying enhanced solubility and elevated overall potential bioavailability in the anode region while lower solubility in the cathode areas. Bioaccumulations of Pb, As and Cs were largely determined by the nature of elements, loading levels and EKF treatment. The native Pb in soil usually is not bioavailable. However, EKF treatment tends to transfer Pb to the SOL and EXC fractions improving the phytoextraction efficiency. Similarly, EKF transferred more EXC As and Cs to the SOL fraction significantly increasing their bioaccumulation in plant roots and shoots. Pb and As were accumulated more in plant roots than in shoots while Cs was accumulated more in shoots due to its similarity of chemical properties to potassium. Indian mustard, spinach and cabbage are good accumulators for Cs. Translocation of Pb, As and Cs from plant roots to shoots were enhanced by EKF. However, this study indicated the overall low phytoextraction efficiency of these plants.

  19. Electro-kinetic remediation coupled with phytoremediation to remove lead, arsenic and cesium from contaminated paddy soil.

    PubMed

    Mao, Xinyu; Han, Fengxiang X; Shao, Xiaohou; Guo, Kai; McComb, Jacqueline; Arslan, Zikri; Zhang, Zhanyu

    2016-03-01

    The objectives of this study were to investigate distribution and solubility of Pb, Cs and As in soils under electrokinetic field and examine the processes of coupled electrokinetic phytoremediation of polluted soils. The elevated bioavailability and bioaccumulation of Pb, As and Cs in paddy soil under an electro-kinetic field (EKF) were studied. The results show that the EKF treatment is effective on lowering soil pH to around 1.5 near the anode which is beneficial for the dissolution of metal(loid)s, thus increasing their overall solubility. The acidification in the anode soil efficiently increased the water soluble (SOL) and exchangeable (EXC) Pb, As and Cs, implying enhanced solubility and elevated overall potential bioavailability in the anode region while lower solubility in the cathode areas. Bioaccumulations of Pb, As and Cs were largely determined by the nature of elements, loading levels and EKF treatment. The native Pb in soil usually is not bioavailable. However, EKF treatment tends to transfer Pb to the SOL and EXC fractions improving the phytoextraction efficiency. Similarly, EKF transferred more EXC As and Cs to the SOL fraction significantly increasing their bioaccumulation in plant roots and shoots. Pb and As were accumulated more in plant roots than in shoots while Cs was accumulated more in shoots due to its similarity of chemical properties to potassium. Indian mustard, spinach and cabbage are good accumulators for Cs. Translocation of Pb, As and Cs from plant roots to shoots were enhanced by EKF. However, this study indicated the overall low phytoextraction efficiency of these plants. PMID:26650421

  20. Fluorescence investigation of the chromatographic interactions of nitrogen heterocycles with deactivated silica

    SciTech Connect

    Burrell, G.J.; Hurtubise, R.J.

    1988-10-15

    Solid-surface fluorescence spectroscopy was used to study the chromatographic interactions of benzo(f)quinoline (B(f)Q) and benzo(h)quinoline (B(h)Q) with water-deactivated silica gel. The results indicated that some of the water was adsorbed on sites in silica that were incapable of proton donation to B(h)Q in the excited singlet state. It was also found that solute localization became more important on the water-deactivated silica. By combination of the luminescence data and the chromatographic data, the mass balance was calculated for three B(h)Q species responsible for the chromatographic bands. Spectral evidence was also obtained that supported a displacement-type of chromatographic mechanism for the systems investigated.

  1. Electrokinetics in polyelectrolyte grafted nanofluidic channels modulated by the ion partitioning effect.

    PubMed

    Poddar, Antarip; Maity, Debonil; Bandopadhyay, Aditya; Chakraborty, Suman

    2016-07-01

    The effects of ion partitioning on the electrokinetics in a polyelectrolyte grafted nanochannel, which is the representative of a soft nanochannel, are analyzed. Earlier studies in this regard have considered low polyelectrolyte layer (PEL) grafting density at the rigid nanochannel wall and, hence, an equal permittivity inside and outside the grafted layer. In order to overcome this shortcoming, the concept of Born energy is revisited. The coupled system of the modified Poisson-Boltzmann and Navier-Stokes equation is solved numerically, going beyond the widely employed Debye-Hückel linearization and low PEL densities. The complex interplay between the hydrodynamics and charge distribution, modulated by the ion partitioning effect, along with their consequent effects on the streaming potential and electrokinetic energy conversion efficiency (EKEC) have been systemically investigated. It has been observed that the ion partitioning effect reduces the EKEC in comparison to the case with equal permittivity up to a certain electrical double layer thickness after which it increases the EKEC. For a high concentration of mobile charges within the PEL, the net gain in the maximum EKEC due to the ion partitioning effect is about 10 fold that of the case when the ion partitioning effect is not considered. We delve into the various scaling regimes in the streaming potential and intriguingly point out the exact location of peaks in efficiency. The present study also reveals the possibility of improvement in streaming potential mediated energy conversion by the use of polyelectrolyte materials, which possess substantially lower dielectric permittivity than the bulk electrolyte. PMID:27306568

  2. Ion-exchange chromatographic analysis of peroxynitric acid.

    PubMed

    Nakashima, Yoichi; Ikawa, Satoshi; Tani, Atsushi; Kitano, Katsuhisa

    2016-01-29

    Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system. The fraction for the peroxynitric acid peak was collected. Ion-exchange chromatographic analysis of this fraction, after standing at room temperature for 24h, showed that the decomposition products were mainly nitrate ions with a very small amount of nitrous acid. The peroxynitric acid peak area correlated perfectly with the total amount of decomposition products. The ion-exchange chromatographic isolation allowed us to evaluate the molar extinction coefficient of peroxynitric acid precisely in a wider wavelength range than previous reports. The value decreases monotonically from 1729±26M(-1)cm(-1) at 200nm to 12.0±0.5M(-1)cm(-1) at 290nm. PMID:26748867

  3. Electrophoretic concentration and sweeping-micellar electrokinetic chromatography analysis of cationic drugs in water samples.

    PubMed

    Wuethrich, Alain; Haddad, Paul R; Quirino, Joselito P

    2015-07-01

    Sample preparation by electrophoretic concentration, followed by analysis using sweeping-micellar electrokinetic chromatography, was studied as a green and simple analytical strategy for the trace analysis of cationic drugs in water samples. Electrophoretic concentration was conducted using 50 mmol/L ammonium acetate at pH 5 as acceptor electrolyte. Electrophoretic concentration was performed at 1.0 kV for 50 min and 0.5 kV and 15 min for purified and 10-fold diluted waste water samples, respectively. Sweeping-micellar electrokinetic chromatography was with 100 mmol/L sodium phosphate at pH 2, 100 mmol/L sodium dodecyl sulfate and 27.5%-v/v acetonitrile as separation electrolyte. The separation voltage was -20 kV, UV-detection was at 200 nm, and the acidified concentrate was injected for 36 s at 1 bar (or 72% of the total capillary length, 60 cm). Both purified water and 10-fold diluted waste water exhibited a linear range of two orders of concentration magnitude. The coefficient of determination, and intra- and interday repeatability were 0.991-0.997, 2.5-6.2, and 4.4-9.7%RSD (n=6), respectively, for purified water. The values were 0.991-0.997, 3.4-7.1, and 8.7-9.8%RSD (n=6), correspondingly, for 10-fold diluted waste water. The method detection limit was in the range from 0.04-0.09 to 1.20-6.97 ng/mL for purified and undiluted waste water, respectively.

  4. Removal of heavy metals from kaolin using an upward electrokinetic soil remedial (UESR) technology.

    PubMed

    Wang, Jing-Yuan; Huang, Xiang-Jun; Kao, Jimmy C M; Stabnikova, Olena

    2006-08-25

    An upward electrokinetic soil remedial (UESR) technology was proposed to remove heavy metals from contaminated kaolin. Unlike conventional electrokinetic treatment that uses boreholes or trenches for horizontal migration of heavy metals, the UESR technology, applying vertical non-uniform electric fields, caused upward transportation of heavy metals to the top surface of the treated soil. The effects of current density, treatment duration, cell diameter, and different cathode chamber influent (distilled water or 0.01 M nitric acid) were studied. The removal efficiencies of heavy metals positively correlated to current density and treatment duration. Higher heavy metals removal efficiency was observed for the reactor cell with smaller diameter. A substantial amount of heavy metals was accumulated in the nearest to cathode 2 cm layer of kaolin when distilled water was continuously supplied to the cathode chamber. Heavy metals accumulated in this layer of kaolin can be easily excavated and disposed off. The main part of the removed heavy metals was dissolved in cathode chamber influent and moved away with cathode chamber effluent when 0.01 M nitric acid was used, instead of distilled water. Energy saving treatment by UESR technology with highest metal removal efficiencies was provided by two regimes: (1) by application of 0.01 M nitric acid as cathode chamber influent, cell diameter of 100 mm, duration of 18 days, and constant voltage of 3.5 V (19.7 k Wh/m(3) of kaolin) and (2) by application of 0.01 M nitric acid as cathode chamber influent, cell diameter of 100 cm, duration of 6 days, and constant current density of 0.191 mA/cm(2) (19.1 k Wh/m(3) of kaolin). PMID:16504386

  5. Electrokinetic-Fenton technology for the remediation of hydrocarbons historically polluted sites.

    PubMed

    Sandu, Ciprian; Popescu, Marius; Rosales, Emilio; Bocos, Elvira; Pazos, Marta; Lazar, Gabriel; Sanromán, M Angeles

    2016-08-01

    The feasibility of the electrokinetic-Fenton technology coupled with surfactants in the treatment of real historically hydrocarbons polluted soils has been studied. The characterisation of these soils from Spain and Romania was performed and identified as diesel and diesel-motor oil spillages, respectively. Moreover, the ageing of the spillages produced by the soil contamination was estimated showing the historical pollution of the sites (around 11 and 20 years for Romanian and Spanish soils, respectively). An ex-situ electrochemical treatment was performed to evaluate the adequacy of surfactants for the degradation of the hydrocarbons present in the soils. It was found an enhancement in the solubilisation and removal of TPHs with percentages increasing from 25.7 to 81.8% by the presence of Tween 80 for Spanish soil and from 15.1% to 71.6% for Triton X100 in Romanian soil. Therefore, the viability of coupling enhanced electrokinetic and Fenton remediation was evaluated through a simulated in-situ treatment at laboratory scale. The results demonstrated that the addition of the selected surfactants improved the solubilisation of the hydrocarbons and influenced the electroosmotic flow with a slight decrease. The efficiency of the treatment increased for both considered soil samples and a significant degradation level of the hydrocarbons compounds was observed. Buffering of pH coupled with the addition of a complexing agent showed to be important in the treatment process, facilitating the conditions for the degradation reactions that take place into the soil matrix. The results demonstrated the effectiveness of the selected techniques for remediation of the investigated soils. PMID:27183337

  6. Separation of steroids using vegetable oils in microemulsion electrokinetic capillary chromatography.

    PubMed

    Sirén, Heli; Vesanen, Sari; Suomi, Johanna

    2014-01-15

    The steroids, hydrocortisone, androstenedione, 17-α-hydroxyprogesterone, testosterone, 17-α-methyltestosterone, and progesterone were separated with microemulsion electrokinetic chromatography (MEEKC) and detected with UV absorption. The microemulsion phases were prepared from both artificial and vegetable oils, from them the first was made of alkane and alcohol and the latter from colza, olive, linseed, and walnut oils. The electrolyte solutions were made to emulsions using sodium dodecyl sulfate and alkaline tetraborate. The solution mixtures made from ethyl acetate, sodium dodecyl sulfate, 1-butanol, acetonitrile, and sodium tetraborate were used as the reference solutions to evaluate the performance of the vegetable oil emulsions. Our study showed that the lipophilic organic phase in the microemulsion did provide resolution improvements but not selectivity changes. The results also correlate with real interactions of the steroids with the lipophilic organic microemulsion phase. The quality of the oils between the manufacturers did not have importance, which was noticed from the equal behavior of the steroids in the vegetable oil emulsions. Detection limits of the steroids in vegetable oil emulsions were at the level of 0.20-0.43μg/L. Thus, they were 2-10 times higher than the concentrations in the partial filling micellar electrokinetic chromatography (PF-MEKC), which we have obtained earlier. The repeatability (RSD%) of the electrophoretic mobilities of the steroids was between 0.50 and 3.70. The RSD% values between the inter-day separations were below 1%, but when walnut and olive oils were used the values exceeded even 10%.

  7. Effects of catholyte conditioning on electrokinetic extraction of copper from mine tailings.

    PubMed

    Zhou, Dong-Mei; Deng, Chang-Fen; Alshawabkeh, Akram N; Cang, Long

    2005-08-01

    Effect of electrokinetic treatment on copper partitioning and distribution in mine tailings were studied. In particular the effects of catholyte enhancement by HAc-NaAc, HCl, HAc-NaAc+EDTA and lactic acid+NaOH were evaluated. The results show that conditioning the catholyte plays a very important role in improving Cu removal. When HAc-NaAc is used in the catholyte, the removal percentage of total Cu from the mine tailings sample reached 12.3% under 40 V in 15 days of treatment. The removal percentage of Cu increased to 31.2% when EDTA was used together with HAc-NaAc in the catholyte. At the same time, increasing the applied voltage and treatment time result in an increase in the Cu removal from the mine tailings. Compared with HAc-NaAc (pH=3.52), the use of lactic acid+NaOH (pH=3.15) in the catholyte resulted in better performance in Cu removal from the mine tailings. HCl treatment resulted in removal of about 17.5% of Cu from the mine tailings; however, it resulted in production of significant amounts of toxic chlorine gas. Copper partitioning in the mine tailings was analyzed before and after the electrokinetic treatments. The analysis was conducted using 0.25 mol/l MgCl2 and 0.5 mol/l HCl as extractants, consequently, to assess the mobility of Cu after treatment. The results showed that lowering the pH of the mine tailings increased the exchangeable Cu fraction (or the portion extracted by MgCl2). Accordingly, further acidification results in an increased mobility of Cu and increase in the environmental risk of mine tailings.

  8. Field Testing of High Current Electrokinetic Nanoparticle Treatment for Corrosion Mitigation in Reinforced Concrete

    NASA Technical Reports Server (NTRS)

    Cardenas, Henry; Alexander, Joshua; Kupwade-Patil, Kunal; Calle, Luz marina

    2010-01-01

    Electrokinetic Nanoparticle (EN) treatment was used as a rapid repair measure to mitigate chloride induced corrosion of reinforced concrete in the field. EN treatment uses an electric field to transport positively charged nanoparticles to the reinforcement through the concrete capillary pores. Cylindrical reinforced concrete specimens were batched with 4.5 wt % salt content (based on cement mass). Three distinct electrokinetic treatments were conducted using high current density (up to 5 A/m2) to form a chloride penetration barrier that was established in 5 days, as opposed to the traditional 6-8 weeks, generally required for electrochemical chloride extraction (ECE). These treatments included basic EN treatment, EN with additional calcium treatment, and basic ECE treatment. Field exposures were conducted at the NASA Beachside Corrosion Test Site, Kennedy Space Center, Florida, USA. The specimens were subjected to sea water immersion at the test site as a posttreatment exposure. Following a 30-day post-treatment exposure period, the specimens were subjected to indirect tensile testing to evaluate treatment impact. The EN treated specimens exhibited 60% and 30% increases in tensile strength as compared to the untreated controls and ECE treated specimens respectively. The surfaces of the reinforcement bars of the control specimens were 67% covered by corrosion products. In contrast, the EN treated specimens exhibited corrosion coverage of only 4%. Scanning electron microscopy (SEM) revealed a dense concrete microstructure adjacent to the bars of the treated specimens as compared to the control and ECE specimens. Energy dispersive spectroscopic (EDS) analysis of the polished EN treated specimens showed a reduction in chloride content by a factor of 20 adjacent to the bars. This study demonstrated that EN treatment was successful in forming a chloride penetration barrier rapidly. This work also showed that the chloride barrier was effective when samples were exposed to

  9. 40 CFR 1065.267 - Gas chromatograph.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Gas chromatograph. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.267 Gas...

  10. 40 CFR 1065.267 - Gas chromatograph.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Gas chromatograph. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.267 Gas...

  11. Nano-fabricated size exclusion chromatograph

    NASA Technical Reports Server (NTRS)

    Svehla, D.; Feldman, S.; Feldman, J.; Grunthaner, F.; Shakkottai, P.; dle Castillo, L.; White, V.

    2002-01-01

    This poster describes the development of a nano-fabricated size exclusion chromatograph (nSEC) based on the principle that molecules traveling through a microcolumn containing nano-fabricated features will have characteristics elution times that directly correlate to molecular weight.

  12. Electrokinetic treatment of an agricultural soil contaminated with heavy metals.

    PubMed

    Figueroa, Arylein; Cameselle, Claudio; Gouveia, Susana; Hansen, Henrik K

    2016-07-28

    The high organic matter content in agricultural soils tends to complex and retain contaminants such as heavy metals. Electrokinetic remediation was tested in an agricultural soil contaminated with Co(+2), Zn(+2), Cd(+2), Cu(+2), Cr(VI), Pb(+2) and Hg(+2). The unenhanced electrokinetic treatment was not able to remove heavy metals from the soil due to the formation of precipitates in the alkaline environment in the soil section close to the cathode. Moreover, the interaction between metals and organic matter probably limited metal transportation under the effect of the electric field. Citric acid and ethylenediaminetetraacetic acid (EDTA) were used in the catholyte as complexing agents in order to enhance the extractability and removal of heavy metals from soil. These complexing agents formed negatively charged complexes that migrated towards the anode. The acid front electrogenerated at the anode favored the dissolution of heavy metals that were transported towards the cathode. The combined effect of the soil pH and the complexing agents resulted in the accumulation of heavy metals in the center of the soil specimen.

  13. Improving electrokinetic microdevice stability by controlling electrolysis bubbles.

    PubMed

    Lee, Hwi Yong; Barber, Cedrick; Minerick, Adrienne R

    2014-07-01

    The voltage-operating window for many electrokinetic microdevices is limited by electrolysis gas bubbles that destabilize microfluidic system causing noise and irreproducible responses above ∼3 V DC and less than ∼1 kHz AC at 3 Vpp. Surfactant additives, SDS and Triton X-100, and an integrated semipermeable SnakeSkin® membrane were employed to control and assess electrolysis bubbles from platinum electrodes in a 180 by 70 μm, 10 mm long microchannel. Stabilized current responses at 100 V DC were observed with surfactant additives or SnakeSkin® barriers. Electrolysis bubble behaviors, visualized via video microscopy at the electrode surface and in the microchannels, were found to be influenced by surfactant function and SnakeSkin® barriers. Both SDS and Triton X-100 surfactants promoted smaller bubble diameters and faster bubble detachment from electrode surfaces via increasing gas solubility. In contrast, SnakeSkin® membranes enhanced natural convection and blocked bubbles from entering the microchannels and thus reduced current disturbances in the electric field. This data illustrated that electrode surface behaviors had substantially greater impacts on current stability than microbubbles within microchannels. Thus, physically blocking bubbles from microchannels is less effective than electrode functionalization approaches to stabilize electrokinetic microfluidic systems. PMID:24648277

  14. Electrokinetic remediation using surfactant-coated ceramic casings

    SciTech Connect

    Mattson, E.D.; Bowman, R.S.; Lindgren, E.R.

    2000-06-01

    Electrokinetic remediation is an emerging technique that can be used to remove metals from saturated or unsaturated soils. In unsaturated soils, control of the medium's water content is essential. Previously used electrode designs have caused detrimental soil wetting due to excess electroosmotic flow out of ceramic-encased anodes. The authors tested a method to reverse the electroosmotic flow at the anode by treating the ceramic casing with the cationic surfactant hexadecyltrimethylammonium (HDTMA). Laboratory tests showed the untreated ceramic had an electroosmotic permeability of 2.4 x 10{sup {minus}5} cm{sup 2} V{sup {minus}1} s{sup {minus}1}. Ceramic treated with HDTMA had an electroosmotic permeability of {minus}1.3 x 10{sup {minus}5} cm{sup 2} V{sup {minus}1} s{sup {minus}1}. Under an applied electric potential, electroosmotic flow was reversed in the HDTMA-treated ceramic, indicating a reversed zeta potential due to formation of an HDTMA bilayer on the ceramic surface. Field tests conducted over a 6-month period showed negligible water loss from HDTMA-treated ceramic compared to untreated ceramics. The results indicated that a surfactant treatment to the anode ceramic casing can greatly improve the application of electrokinetics in unsaturated environments.

  15. Electrokinetic treatment of an agricultural soil contaminated with heavy metals.

    PubMed

    Figueroa, Arylein; Cameselle, Claudio; Gouveia, Susana; Hansen, Henrik K

    2016-07-28

    The high organic matter content in agricultural soils tends to complex and retain contaminants such as heavy metals. Electrokinetic remediation was tested in an agricultural soil contaminated with Co(+2), Zn(+2), Cd(+2), Cu(+2), Cr(VI), Pb(+2) and Hg(+2). The unenhanced electrokinetic treatment was not able to remove heavy metals from the soil due to the formation of precipitates in the alkaline environment in the soil section close to the cathode. Moreover, the interaction between metals and organic matter probably limited metal transportation under the effect of the electric field. Citric acid and ethylenediaminetetraacetic acid (EDTA) were used in the catholyte as complexing agents in order to enhance the extractability and removal of heavy metals from soil. These complexing agents formed negatively charged complexes that migrated towards the anode. The acid front electrogenerated at the anode favored the dissolution of heavy metals that were transported towards the cathode. The combined effect of the soil pH and the complexing agents resulted in the accumulation of heavy metals in the center of the soil specimen. PMID:27127923

  16. Induced electrokinetic transport in micro-nanofluidic interconnect devices.

    PubMed

    Jin, Xiaozhong; Joseph, Sony; Gatimu, Enid N; Bohn, Paul W; Aluru, N R

    2007-12-18

    Hybrid micro-nanofluidic interconnect devices can be used to control analyte transfer from one microchannel to the other through a nanochannel under rest, injection, and recovery stages of operation by varying the applied potential bias. Using numerical simulations based on coupled transient Poisson-Nernst-Planck and Stokes equations, we examine the electrokinetic transport in a gateable device consisting of two 100 microm long, 1 microm wide negatively charged microchannels connected by a 1 microm long, 10 nm wide positively charged nanochannel under both positive and negative bias potentials. During injection, accumulation of ions is observed at the micro-nano interface region with the positive potential and depletion of ions is observed at the other micro-nano junction region. Net space charge in the depletion region gives rise to nonlinear electrokinetic transport during the recovery stage due to induced pressure, induced electroosmotic flow of the second kind, and complex flow circulations. Ionic currents are computed as a function of time for both positive and negative bias potentials for the three stages. Analytical expressions derived for ion current variation are in agreement with the simulated results. In the presence of multiple accumulation or depletion regions, we show that a hybrid micro-nano device can be designed to function as a logic gate.

  17. Pore network model of electrokinetic transport through charged porous media

    NASA Astrophysics Data System (ADS)

    Obliger, Amaël; Jardat, Marie; Coelho, Daniel; Bekri, Samir; Rotenberg, Benjamin

    2014-04-01

    We introduce a method for the numerical determination of the steady-state response of complex charged porous media to pressure, salt concentration, and electric potential gradients. The macroscopic fluxes of solvent, salt, and charge are computed within the framework of the Pore Network Model (PNM), which describes the pore structure of the samples as networks of pores connected to each other by channels. The PNM approach is used to capture the couplings between solvent and ionic flows which arise from the charge of the solid surfaces. For the microscopic transport coefficients on the channel scale, we take a simple analytical form obtained previously by solving the Poisson-Nernst-Planck and Stokes equations in a cylindrical channel. These transport coefficients are upscaled for a given network by imposing conservation laws for each pores, in the presence of macroscopic gradients across the sample. The complex pore structure of the material is captured by the distribution of channel diameters. We investigate the combined effects of this complex geometry, the surface charge, and the salt concentration on the macroscopic transport coefficients. The upscaled numerical model preserves the Onsager relations between the latter, as expected. The calculated macroscopic coefficients behave qualitatively as their microscopic counterparts, except for the permeability and the electro-osmotic coupling coefficient when the electrokinetic effects are strong. Quantitatively, the electrokinetic couplings increase the difference between the macroscopic coefficients and the corresponding ones for a single channel of average diameter.

  18. Improving electrokinetic microdevice stability by controlling electrolysis bubbles.

    PubMed

    Lee, Hwi Yong; Barber, Cedrick; Minerick, Adrienne R

    2014-07-01

    The voltage-operating window for many electrokinetic microdevices is limited by electrolysis gas bubbles that destabilize microfluidic system causing noise and irreproducible responses above ∼3 V DC and less than ∼1 kHz AC at 3 Vpp. Surfactant additives, SDS and Triton X-100, and an integrated semipermeable SnakeSkin® membrane were employed to control and assess electrolysis bubbles from platinum electrodes in a 180 by 70 μm, 10 mm long microchannel. Stabilized current responses at 100 V DC were observed with surfactant additives or SnakeSkin® barriers. Electrolysis bubble behaviors, visualized via video microscopy at the electrode surface and in the microchannels, were found to be influenced by surfactant function and SnakeSkin® barriers. Both SDS and Triton X-100 surfactants promoted smaller bubble diameters and faster bubble detachment from electrode surfaces via increasing gas solubility. In contrast, SnakeSkin® membranes enhanced natural convection and blocked bubbles from entering the microchannels and thus reduced current disturbances in the electric field. This data illustrated that electrode surface behaviors had substantially greater impacts on current stability than microbubbles within microchannels. Thus, physically blocking bubbles from microchannels is less effective than electrode functionalization approaches to stabilize electrokinetic microfluidic systems.

  19. Electrokinetic shape changes of cochlear outer hair cells.

    PubMed

    Kachar, B; Brownell, W E; Altschuler, R; Fex, J

    Rapid mechanical changes have been associated with electrical activity in a variety of non-muscle excitable cells. Recently, mechanical changes have been reported in cochlear hair cells. Here we describe electrically evoked mechanical changes in isolated cochlear outer hair cells (OHCs) with characteristics which suggest that direct electrokinetic phenomena are implicated in the response. OHCs make up one of two mechanosensitive hair cell populations in the mammalian cochlea; their role may be to modulate the micromechanical properties of the hearing organ through mechanical feedback mechanisms. In the experiments described here, we applied sinusoidally modulated electrical potentials across isolated OHCs; this produced oscillatory elongation and shortening of the cells and oscillatory displacements of intracellular organelles. The movements were a function of the direction and strength of the electrical field, were inversely related to the ionic concentration of the medium, and occurred in the presence of metabolic uncouplers. The cylindrical shape of the OHCs and the presence of a system of membranes within the cytoplasm--laminated cisternae--may provide the anatomical substrate for electrokinetic phenomena such as electro-osmosis.

  20. Electrokinetic shape changes of cochlear outer hair cells

    NASA Astrophysics Data System (ADS)

    Kachar, Bechara; Brownell, William E.; Altschuler, Richard; Fex, Jörgen

    1986-07-01

    Rapid mechanical changes have been associated with electrical activity in a variety of non-muscle excitable cells1-5. Recently, mechanical changes have been reported in cochlear hair cells6-8. Here we describe electrically evoked mechanical changes in isolated cochlear outer hair cells (OHCs) with characteristics which suggest that direct electrokinetic phenomena are implicated in the response. OHCs make up one of two mechanosensitive hair cell populations in the mammalian cochlea; their role may be to modulate the micromechanical properties of the hearing organ through mechanical feedback mechanisms6-10. In the experiments described here, we applied sinusoidally modulated electrical potentials across isolated OHCs; this produced oscillatory elongation and shortening of the cells and oscillatory displacements of intracellular organdies. The movements were a function of the direction and strength of the electrical field, were inversely related to the ionic concentration of the medium, and occurred in the presence of metabolic uncouplers. The cylindrical shape of the OHCs and the presence of a system of membranes within the cytoplasm-laminated cisternae11-may provide the anatomical substrate for electrokinetic phenomena such as electro-osmosis12,13.

  1. Method for the chromatographic separation of cations from aqueous samples

    DOEpatents

    Horwitz, E. Philip; Chiarizia, Renato; Dietz, Mark L.

    1997-01-01

    An extraction chromatographic material for extracting metal cations from a iquid stream. The extraction chromatographic material is prepared by adsorbing a diesterified methanediphosphonic acid on an inert particulate support.

  2. Method for the chromatographic separation of cations from aqueous samples

    DOEpatents

    Horwitz, E.P.; Chiarizia, R.; Dietz, M.L.

    1997-07-29

    An extraction chromatographic material is described for extracting metal cations from a liquid stream. The extraction chromatographic material is prepared by adsorbing a diesterified methanediphosphonic acid on an inert particulate support. 7 figs.

  3. Method for the chromatographic separation of cations from aqueous samples

    DOEpatents

    Horwitz, E.P.; Chiarizia, R.; Dietz, M.L.

    1998-12-22

    An extraction chromatographic material is described for extracting metal cations from a liquid stream. The extraction chromatographic material is prepared by adsorbing a diesterified methane-diphosphonic acid on an inert particulate support. 7 figs.

  4. Method for the chromatographic separation of cations from aqueous samples

    DOEpatents

    Horwitz, E. Philip; Chiarizia, Renato; Dietz, Mark L.

    1998-12-22

    An extraction chromatographic material for extracting metal cations from a liquid stream. The extraction chromatographic material is prepared by adsorbing a diesterified methanediphosphonic acid on an inert particulate support.

  5. Method to fabricate silicon chromatographic column comprising fluid ports

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.; Heller, Edwin J.; Adkins, Douglas R.

    2004-03-02

    A new method for fabricating a silicon chromatographic column comprising through-substrate fluid ports has been developed. This new method enables the fabrication of multi-layer interconnected stacks of silicon chromatographic columns.

  6. Solid/solution Cu fractionations/speciation of a Cu contaminated soil after pilot-scale electrokinetic remediation and their relationships with soil microbial and enzyme activities.

    PubMed

    Wang, Quan-Ying; Zhou, Dong-Mei; Cang, Long; Li, Lian-Zhen; Wang, Peng

    2009-01-01

    The aim of this study was to investigate the detailed metal speciation/fractionations of a Cu contaminated soil before and after electrokinetic remediation as well as their relationships with the soil microbial and enzyme activities. Significant changes in the exchangeable and adsorbed-Cu fractionations occurred after electrokinetic treatment, while labile soil Cu in the solution had a tendency to decrease from the anode to the cathode, and the soil free Cu(2+) ions were mainly accumulated in the sections close to the cathode. The results of regression analyses revealed that both the soil Cu speciation in solution phase and the Cu fractionations in solid phase could play important roles in the changes of the soil microbial and enzyme activities. Our findings suggest that the bioavailability of soil heavy metals and their ecotoxicological effects on the soil biota before and after electroremediation can be better understood in terms of their chemical speciation and fractionations. PMID:19427727

  7. Chromatographic and related reactors. Final report, 1 October 1983-30 September 1987

    SciTech Connect

    Langer, S.H.

    1988-01-07

    Several variations of gas- and liquid-column chromatographic reactors were investigated. In connection with this, new information on the kinetics and course of the base-catalyzed esterification reaction of tetrachloroterephthaloyl chloride and its derivatives was obtained with /sup 13/C Nuclear Magnetic Resonance. The operation and conversion in a reverse-phase liquid chromatographic reactor could be analyzed on a quantitative basis when consideration was given to the associative interaction between the stationary phase and elements of the mobile phase. Furthermore, the composition and models for the stationary phase could be examined on the basis of the kinetics of reaction of the tetrachloroterephthaloyl derivatives. A related procedure for determining the phase ratio was developed. Mass-transfer limitations for chromatographic reactions were also analyzed. Incorporation of a void column between two packed liquid-chromatographic columns made it possible to decouple esterification-rate constants for both the mobile and stationary phase. The stopped-flow liquid chromatographic reactor was found to be viable for conversions and operation but not amenable to quantitive analysis because of ionic-strength effects with the systems. Operation of a version of the stopped-flow-gas chromatographic reactor was successful and applications to studies of catalytic reactions were demonstrated. The rate of the CO methanation reaction even could be measured at room temperature on supported nickel, ruthenium, and cobalt catalysts.

  8. Five-descriptor model to predict the chromatographic sequence of natural compounds.

    PubMed

    Hou, Shuying; Wang, Jinhua; Li, Zhangming; Wang, Yang; Wang, Ying; Yang, Songling; Xu, Jia; Zhu, Wenliang

    2016-03-01

    Despite the recent introduction of mass detection techniques, ultraviolet detection is still widely applied in the field of the chromatographic analysis of natural medicines. Here, a neural network cascade model consisting of nine small artificial neural network units was innovatively developed to predict the chromatographic sequence of natural compounds by integrating five molecular descriptors as the input. A total of 117 compounds of known structure were collected for model building. The order of appearance of each compound was determined in gradient chromatography. Strong linear correlation was found between the predicted and actual chromatographic position orders (Spearman's rho = 0.883, p < 0.0001). Application of the model to the external validation set of nine natural compounds was shown to dramatically increase the prediction accuracy of the real chromatographic order of multiple compounds. A case study shows that chromatographic sequence prediction based on a neural network cascade facilitated compound identification in the chromatographic fingerprint of Radix Salvia miltiorrhiza. For natural medicines of known compound composition, our method provides a feasible means for identifying the constituents of interest when only ultraviolet detection is available.

  9. Emergency gas-chromatographic assay of phenobarbital and phenytoin and liquid-chromatographic assay of theophylline.

    PubMed

    Shihabi, Z K

    1978-09-01

    Phenobarbital and phenytoin are extracted and concentrated in a single step, without solvent evaporation, followed by on-column methylation and gas-chromatographic quanitation. A similar extraction step for the assay of theophylline by high-pressure liquid chromatography is described. The extraction step can be completed in less than 2 min, the chromatographic step in less than 8 min. This extraction method yields clean chromatograms, avoids evaporating health-hazardous solvents, and is applicable to other drugs.

  10. Norelgestromin/ethinyl estradiol intravenous infusion formulation optimization, stability and compatibility testing: A case study to overcome polysorbate 80 interference in chromatographic analysis.

    PubMed

    Abdallah, Inas A; Hammell, Dana C; Hassan, Hazem E; Stinchcomb, Audra L

    2016-06-01

    Norelgestromin/ethinyl estradiol is a progestin/estrogen combination hormonal contraceptive indicated for the prevention of pregnancy in women. The very poor solubility and wettability of these drugs, along with their high potency (adsorption issues), give rise to difficulties in designing intravenous (IV) formulations to assess absolute bioavailability of products containing both drugs. The purpose of this study was to develop an IV formulation, evaluate its stability under different conditions and evaluate its compatibility with IV sets for potential use in absolute bioavailability studies in humans. Also, a selective high-performance liquid chromatography (HPLC) method for quantification of ethinyl estradiol and norelgestromin in polysorbate 80 matrix was developed and validated. Norelgestromin/ethinyl estradiol IV solution was prepared using sterile water for injection with 2.5% ethanol and 2.5% polysorbate 80 as a cosolvent/surfactant system to obtain a final drug solution of 25μg ethinyl estradiol and 252μg norelgestromin from a concentrated stock drug solution. The stabilities of the concentrated stock and IV solutions were assessed after storing them in the refrigerator (3.7±0.6°C) and at room temperature (19.5±0.5°C), respectively. Additional studies were conducted to examine the stability of the IV solution using an Alarias(®) low sorbing IV administration set with and without an inline filter. The solution was allowed to drip at 1mL/min over a 60min period. Samples were obtained at the beginning, middle and end of the 60min duration. The chemical stability was evaluated for up to 10 days. Norelgestromin and ethinyl estradiol concentration, purity, and degradant levels were determined using the HPLC method. The norelgestromin/ethinyl estradiol IV formulation met the chemical stability criteria when tested on day 1 through day 9 (216h). Norelgestromin concentrations assayed in stock and IV solutions were in the range of 90.0-98.5% and 90

  11. Norelgestromin/ethinyl estradiol intravenous infusion formulation optimization, stability and compatibility testing: A case study to overcome polysorbate 80 interference in chromatographic analysis.

    PubMed

    Abdallah, Inas A; Hammell, Dana C; Hassan, Hazem E; Stinchcomb, Audra L

    2016-06-01

    Norelgestromin/ethinyl estradiol is a progestin/estrogen combination hormonal contraceptive indicated for the prevention of pregnancy in women. The very poor solubility and wettability of these drugs, along with their high potency (adsorption issues), give rise to difficulties in designing intravenous (IV) formulations to assess absolute bioavailability of products containing both drugs. The purpose of this study was to develop an IV formulation, evaluate its stability under different conditions and evaluate its compatibility with IV sets for potential use in absolute bioavailability studies in humans. Also, a selective high-performance liquid chromatography (HPLC) method for quantification of ethinyl estradiol and norelgestromin in polysorbate 80 matrix was developed and validated. Norelgestromin/ethinyl estradiol IV solution was prepared using sterile water for injection with 2.5% ethanol and 2.5% polysorbate 80 as a cosolvent/surfactant system to obtain a final drug solution of 25μg ethinyl estradiol and 252μg norelgestromin from a concentrated stock drug solution. The stabilities of the concentrated stock and IV solutions were assessed after storing them in the refrigerator (3.7±0.6°C) and at room temperature (19.5±0.5°C), respectively. Additional studies were conducted to examine the stability of the IV solution using an Alarias(®) low sorbing IV administration set with and without an inline filter. The solution was allowed to drip at 1mL/min over a 60min period. Samples were obtained at the beginning, middle and end of the 60min duration. The chemical stability was evaluated for up to 10 days. Norelgestromin and ethinyl estradiol concentration, purity, and degradant levels were determined using the HPLC method. The norelgestromin/ethinyl estradiol IV formulation met the chemical stability criteria when tested on day 1 through day 9 (216h). Norelgestromin concentrations assayed in stock and IV solutions were in the range of 90.0-98.5% and 90

  12. Chromatographic separation of fructose from date syrup.

    PubMed

    Al Eid, Salah M

    2006-01-01

    The objective of this study is to provide a process for separating fructose from a mixture of sugars containing essentially fructose and glucose, obtained from date palm fruits. The extraction procedure of date syrup from fresh dates gave a yield of 86.5% solids after vacuum drying. A process for separating fructose from an aqueous solution of date syrup involved adding the date syrup solutions (20, 30 and 40% by weight) to a chromatographic column filled with Dowex polystyrene strong cation exchange gel matrix resin Ca2 + and divinylbenzene, a functional group, sulfonic acid, particle size 320 microm, with a flow rate of 0.025 and 0.05 bed volume/min, under 30 and 70 degrees C column temperature. After the date sugar solution batch, a calculated quantity of water was added to the column. Glucose was retained by the resin more weakly than fructose and proceeded faster into the water batch flowing ahead. Three fractions were collected: a glucose-rich fraction, a return fraction, and a fructose-rich fraction. The return fraction is based on when the peaks of fructose and glucose were reached, which could be determined by means of an analyzer (polarimeter) based on the property of glucose and fructose solutions to turn the polarization level of polarized light. A high yield of fructose is obtained at 70 degrees C column temperature with a flow rate of 0.025 bed volume/min and date syrup solution containing 40% sugar concentration. The low recovery by weight obtained using date syrup solutions having a sugar concentration of 20 and 30%, encourages the use of a concentration of 40%. However, with the 40% date syrup supply the average concentrations of glucose and fructose in the return fractions were more than 40%, which can be used for diluting the thick date syrup solution extracted from dates.

  13. Chromatographic separation of fructose from date syrup.

    PubMed

    Al Eid, Salah M

    2006-01-01

    The objective of this study is to provide a process for separating fructose from a mixture of sugars containing essentially fructose and glucose, obtained from date palm fruits. The extraction procedure of date syrup from fresh dates gave a yield of 86.5% solids after vacuum drying. A process for separating fructose from an aqueous solution of date syrup involved adding the date syrup solutions (20, 30 and 40% by weight) to a chromatographic column filled with Dowex polystyrene strong cation exchange gel matrix resin Ca2 + and divinylbenzene, a functional group, sulfonic acid, particle size 320 microm, with a flow rate of 0.025 and 0.05 bed volume/min, under 30 and 70 degrees C column temperature. After the date sugar solution batch, a calculated quantity of water was added to the column. Glucose was retained by the resin more weakly than fructose and proceeded faster into the water batch flowing ahead. Three fractions were collected: a glucose-rich fraction, a return fraction, and a fructose-rich fraction. The return fraction is based on when the peaks of fructose and glucose were reached, which could be determined by means of an analyzer (polarimeter) based on the property of glucose and fructose solutions to turn the polarization level of polarized light. A high yield of fructose is obtained at 70 degrees C column temperature with a flow rate of 0.025 bed volume/min and date syrup solution containing 40% sugar concentration. The low recovery by weight obtained using date syrup solutions having a sugar concentration of 20 and 30%, encourages the use of a concentration of 40%. However, with the 40% date syrup supply the average concentrations of glucose and fructose in the return fractions were more than 40%, which can be used for diluting the thick date syrup solution extracted from dates. PMID:16849117

  14. ENANTIOSEPARATION OF MALATHION, CRUFORMATE, AND FENSULFOTHION ORGANOSPHOSPHORUS PESTICIDES BY MIXED-MODE ELECTROKINETIC CAPILLARY CHROMATOGRAPHY

    EPA Science Inventory

    Mixed-mode electrokinetic capillary chromatography (mixed-ECC) has been used for the enantioseparation of organophosphorus pesticides. In mixed-ECC, a combination of three pseudostationary phases including surfactants, neutral, and charged cyclodextrins, are used to resolve very ...

  15. Treatment of contaminated groundwater in sandy layer under river bank by electrokinetic and ultrasonic technology.

    PubMed

    Chung, Ha I

    2007-01-01

    A series of laboratory experiments involving simple, ultrasonic, electrokinetic, electrokinetic/ ultrasonic flushing test were carried out for treatment and removal of heavy metal and hydrocarbon from contaminated groundwater in sandy layers under a river bank. The test results show that the electrokinetic/ultrasonic flushing technique is most effective for the removal of heavy metal and hydrocarbon from contaminated sandy layers by the coupling action of their own phenomena. It is shown that the electrokinetic technique is most effective to enhance the removal efficiency of heavy metal contaminants such as cadmium from contaminated sandy soil under the river bank; on the other hand the ultrasonic technique is most effective to enhance the removal efficiency of hydrocarbon contaminant, such as diesel fuel from contaminated soil. PMID:17305157

  16. A method for measuring electrokinetic coefficients of porous media and its potential application in hydrocarbon exploration

    NASA Astrophysics Data System (ADS)

    Jiang, Y. G.; Shan, F. K.; Jin, H. M.; Zhou, L. W.; Sheng, Ping

    We have designed and constructed a compact cell to measure the electrokinetic coefficients in the frequency range of interest to hydrocarbon exploration, 20 to 100 Hz. Experimental results are presented on the frequency dependence of the electrokinetic coefficients, and dynamic permeability of a porous rock saturated with either 0.1 mole brine or transformer oil. In particular, the brine-saturated electro-osmosis coefficient is found to be two orders of magnitude larger than that saturated with transformer oil; whereas for the streaming potential the ratio of the two cases is in the reverse. These results, when combined with viscosity and electrical conductivity values, lead consistently to the fact that the electrokinetic Onsager coefficient of brine-saturated samples is three orders of magnitude larger than that of oil-saturated samples. This difference provides a strong motivation to further explore the potential application of electrokinetic Onsager coefficient as a hydrocarbon indicator.

  17. Excitation of electrokinetic effects at the shallow bottom by surface waves

    NASA Astrophysics Data System (ADS)

    Yegorov, I. V.; Palshin, N. A.

    2015-05-01

    The generation of electric field fluctuations caused by electrokinetic effects observed at the bottoms of shallow basins with low salinity are considered in addition to natural variable ionospheric-magnetospheric electromagnetic fields. The electric field excitation model is considered for the cases with long surface waves and for the case when the wavelength is smaller than the water depth. The model has been mathematically described, and bottom pressure fluctuations caused by surface waves and the values of the electric field generated by these fluctuations as a result of electrokinetic effects have been obtained. It has been indicated that nonlinear effects in standing waves, formed by short progressive waves as well as by long waves, can cause electrokinetic electric fields of the same order of magnitude in the bottom layer. Thus, a method for estimating electrokinetic noise generated by surface waves has been proposed for the first time.

  18. Treatment of contaminated groundwater in sandy layer under river bank by electrokinetic and ultrasonic technology.

    PubMed

    Chung, Ha I

    2007-01-01

    A series of laboratory experiments involving simple, ultrasonic, electrokinetic, electrokinetic/ ultrasonic flushing test were carried out for treatment and removal of heavy metal and hydrocarbon from contaminated groundwater in sandy layers under a river bank. The test results show that the electrokinetic/ultrasonic flushing technique is most effective for the removal of heavy metal and hydrocarbon from contaminated sandy layers by the coupling action of their own phenomena. It is shown that the electrokinetic technique is most effective to enhance the removal efficiency of heavy metal contaminants such as cadmium from contaminated sandy soil under the river bank; on the other hand the ultrasonic technique is most effective to enhance the removal efficiency of hydrocarbon contaminant, such as diesel fuel from contaminated soil.

  19. Chromatographic retention behaviour of monosubstituted benzene derivatives on porous graphitic carbon and octadecyl-bonded silica studied using molecular modelling and quantitative structure-retention relationships.

    PubMed

    De Matteis, Cristina I; Simpson, David A; Euerby, Melvin R; Shaw, P Nicholas; Barrett, David A

    2012-03-16

    The retention behaviour of a series of 28 monosubstituted benzenes, representing a diverse range of functional groups and substituent shape, were investigated using porous graphitic carbon (PGC) and octadecyl-bonded silica (ODS) stationary phases. For the majority of analytes retention on PGC was greater than on ODS, and in most cases this effect occurred at both pH 2.5 and 7.0. The main trends observed on PGC (in comparison with ODS) were: (i) similar or reduced retention of low polarity molecules such as the hydrocarbon and halogenated analytes; (ii) increased retention of conjugated analytes with extended planarity; (iii) increased retention of polar and charged species; and (iv) substantial increases in retention for selected polar and negatively charged analytes, including some ionised and unionised acid analytes. Poor retention of positively charged analytes was observed on both stationary phases. Molecular modelling studies have explored the geometry of π-π stacking interactions in retention on PGC and have highlighted the strong retention of large conjugated analytes, with extended planar conformations, which can interact with the graphite surface with cofacial geometry. Quantitative structure-retention relationships showed the importance of hydrophobic (π) and electronic factors (e.g. mean polarisability and LUMO energy) in retention on PGC, whilst retention on ODS was correlated to hydrophobicity (logP and π). PMID:22305358

  20. Liquid chromatograph/tandem mass spectrometry assay for the simultaneous determination of chlorogenic acid and cinnamic acid in plasma and its application to a pharmacokinetic study.

    PubMed

    Zhang, Jun; Chen, Min; Ju, Wenzheng; Liu, Shijia; Xu, Meijuan; Chu, Jihong; Wu, Ting

    2010-02-01

    A rapid and high sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for simultaneous determination of chlorogenic acid and cinnamic acid in human plasma was developed. The analytes and internal standard (IS), tinidazole, were extracted from human plasma via liquid/liquid extraction with ether-ethyl acetate (1:1, v/v) and separated on an Agilent Zorbax SB C18 column within 5min. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring (MRM) and negative ion mode. The precursor to product ion transitions monitored for chlorogenic acid, cinnamic acid and IS were m/z 352.9-->191.1, 146.8-->103.1, 245.6-->126.0, respectively. The assay was validated with linear range of 1.00-800.00ng/mL for chlorogenic acid and 0.50-400.00ng/mL for cinnamic acid. The intra- and inter-day precisions (RSD%) were within 9.05% for each analyte. The absolution recoveries were greater than 74.62% for chlorogenic acid and 76.21% for cinnamic acid. Each analyte was proved to be stable during all sample storage, preparation and analytic procedures. The method was successfully applied to a pharmacokinetic study of Mailuoning injection in 10 healthy volunteers.

  1. Determination of triazine herbicides: development of an electroanalytical method utilizing a solid amalgam electrode that minimizes toxic waste residues, and a comparative study between voltammetric and chromatographic techniques.

    PubMed

    De Souza, Djenaine; de Toledo, Renata A; Galli, Andressa; Salazar-Banda, Giancarlo R; Silva, Maria R C; Garbellini, Gustavo S; Mazo, Luiz H; Avaca, Luis A; Machado, Sergio A S

    2007-03-01

    The use of a copper solid amalgam electrode (CuSAE) for the analytical determination of triazine herbicides (atrazine and ametryne) instead of the conventional hanging mercury drop electrode (HMDE) is reported. The results obtained using electroanalytical methods utilizing each of these electrodes were also compared with those provided by the HPLC technique. The results indicated that the CuSAE electrode can be used to detect the herbicides studied, since the detection limits reached using the electrode (3.06 microg L-1 and 3.78 microg L-1 for atrazine and ametryne, respectively) are lower than the maximum values permitted by CONAMA (Brazilian National Council for the Environment) for wastewaters (50 microg L-1) and by the US EPA (Environmental Protection Agency of the United States) in natural water samples (10.00 microg L-1). An electroanalytical methodology employing CuSAE and square wave voltammetry (SWV) was successfully applied to the determination of atrazine and ametryne in natural water samples, yielding good recoveries (70.30%-79.40%). This indicates that the CuSAE provides a convenient substitute for the HMDE, particularly since the CuSAE minimizes the toxic waste residues produced by the use of mercury in HDME-based analyses.

  2. Application of gas-diffusion microextraction to solid samples using the chromatographic determination of α-diketones in bread as a case study.

    PubMed

    Ferreira, Rui César; Ramos, Rui Miguel; Gonçalves, Luís Moreira; Almeida, Paulo Joaquim; Rodrigues, José António

    2015-05-21

    Gas-diffusion microextraction (GDME) was applied to the extraction of vicinal diketones in bread samples aimed at the determination of these compounds by high-performance liquid chromatography with ultraviolet detection (HPLC-UV). For the first time, GDME was used for direct chemical determination in solid samples, i.e. avoiding any sample preparation prior to extraction. Different extraction parameters were studied and optimized, namely temperature, time and chemical composition of the acceptor solution where o-phenylenediamine was used as a derivatizing agent, originating quinoxalines that could be determined at 315 nm. GDME demonstrated to be a good tool for the sampling of volatile compounds in solid samples with suitable method features for butane-2,3-dione (diacetyl, DC), pentane-2,3-dione (PN) and hexane-2,3-dione (HX): low LODs (6.0, 8.6 and 12 μg kg(-1), for DC, PN and HX respectively) and LOQs (20, 29 and 38 μg kg(-1), for DC, PN and HX respectively), r(2) above 0.990, and CV around 5%. The developed methodology was applied to the determination of different bread samples and was used to reveal the decrease of α-diketones in bread during the timeframe of a week. PMID:25868491

  3. Electrokinetic In Situ Treatment of Metal-Contaminated Soil

    NASA Technical Reports Server (NTRS)

    Quinn, Jacqueline; Clausen, Christian A., III; Geiger, Cherie; Reinhart, Debra

    2004-01-01

    An electrokinetic technique has been developed as a means of in situ remediation of soils, sludges, and sediments that are contaminated with heavy metals. Examples of common metal contaminants that can be removed by this technique include cadmium, chromium, zinc, lead, mercury, and radionuclides. Some organic contaminants can also be removed by this technique. In the electrokinetic technique, a low-intensity direct current is applied between electrodes that have been implanted in the ground on each side of a contaminated soil mass. The electric current causes electro-osmosis and migration of ions, thereby moving aqueous-phase subsurface contaminants from one electrode to the other. The half reaction at the anode yields H+, thereby generating an acid front that travels from the anode toward the cathode. As this acid front passes through a given location, the local increase in acidity increases the solubility of cations that were previously adsorbed on soil particles. Ions are transported towards one electrode or the other which one depending on their respective electric charges. Upon arrival at the electrodes, the ionic contaminants can be allowed to become deposited on the electrodes or can be extracted to a recovery system. Surfactants and other reagents can be introduced at the electrodes to enhance rates of removal of contaminants. Placements of electrodes and concentrations and rates of pumping of reagents can be adjusted to maximize efficiency. The basic concept of electrokinetic treatment of soil is not new. What is new here are some of the details of application and the utilization of this technique as an alternative to other techniques (e.g., flushing or bioremediation) that are not suitable for treating soils of low hydraulic conductivity. Another novel aspect is the use of this technique as a less expensive alternative to excavation: The cost advantage over excavation is especially large in settings in which contaminated soil lies near and/or under

  4. A case of biliary stones and anastomotic biliary stricture after liver transplant treated with the rendez - vous technique and electrokinetic lithotritor

    PubMed Central

    Pisa, Marta Di; Traina, Mario; Miraglia, Roberto; Maruzzelli, Luigi; Volpes, Riccardo; Piazza, Salvatore; Luca, Angelo; Gridelli, Bruno

    2008-01-01

    The paper studies the combined radiologic and endoscopic approach (rendez vous technique) to the treatment of the biliary complications following liver transplant. The “rendez-vous” technique was used with an electrokinetic lithotripter, in the treatment of a biliary anastomotic stricture with multiple biliary stones in a patient who underwent orthotopic liver transplant. In this patient, endoscopic or percutaneous transhepatic management of the biliary complication failed. The combined approach, percutaneous transhepatic and endoscopic treatment (rendez-vous technique) with the use of an electrokinetic lithotritor, was used to solve the biliary stenosis and to remove the stones. Technical success, defined as disappearance of the biliary stenosis and stone removal, was obtained in just one session, which definitively solved the complications. The combined approach of percutaneous transhepatic and endoscopic (rendez-vous technique) treatment, in association with an electrokinetic lithotritor, is a safe and feasible alternative treatment, especially after the failure of endoscopic and/or percutaneous trans-hepatic isolated procedures. PMID:18473423

  5. A combination of electrokinetics and Pd/Fe PRB for the remediation of pentachlorophenol-contaminated soil.

    PubMed

    Li, Zhirong; Yuan, Songhu; Wan, Jinzhong; Long, Huayun; Tong, Man

    2011-06-01

    Electrokinetic (EK) remediation of pentachlorophenol (PCP)-contaminated soil is difficult because PCP dissociates at different pH values along soil column and shows different transport behaviors near anode and cathode. In the present study, a permeable reactive barrier (PRB) filled with reactive Pd/Fe particles was installed between anode and cathode to reach the dechlorination of PCP during its EK movement. When PRB was installed at the position of 0.3 (normalized distance from anode), PCP in the section from anode to PRB could transport through PRB, while PCP in the section from cathode to PRB was accumulated near PRB. PCP was hardly dechlorinated by PRB wherein high pH was reached. When PRB was installed at the position of 0.5 and the pH in the PRB was decreased by periodical injection of HAc, 49% of PCP was removed, and 22.9% was recovered as phenol which was mostly collected in catholyte. The mechanism of PCP removal was proposed as the EK movement of PCP into the PRB compartment, the complete dechlorination of PCP to phenol by Pd/Fe in the PRB compartment, and the subsequent removal of phenol by electroosmosis. This study proved that the combination of electrokinetics and Pd/Fe PRB was effective for the remediation of PCP-contaminated soil.

  6. Electrokinetic-Enhanced Remediation of Phenanthrene-Contaminated Soil Combined with Sphingomonas sp. GY2B and Biosurfactant.

    PubMed

    Lin, Weijia; Guo, Chuling; Zhang, Hui; Liang, Xujun; Wei, Yanfu; Lu, Guining; Dang, Zhi

    2016-04-01

    Electrokinetic-microbial remediation (EMR) has emerged as a promising option for the removal of polycyclic aromatic hydrocarbons (PAHs) from contaminated soils. The aim of this study was to enhance degradation of phenanthrene (Phe)-contaminated soils using EMR combined with biosurfactants. The electrokinetic (EK) remediation, combined with Phe-degrading Sphingomonas sp. GY2B, and biosurfactant obtained by fermentation of Pseudomonas sp. MZ01, degraded Phe in the soil with an efficiency of up to 65.1 % at the anode, 49.9 % at the cathode after 5 days of the treatment. The presence of biosurfactants, electricity, and a neutral electrolyte stimulated the growth of the degrading bacteria as shown by a rapid increase in microbial biomass with time. The electrical conductivity and pH changed little during the course of the treatment, which benefitted the growth of microorganisms and the remediation of Phe-contaminated soil. The EMR system with the addition of biosurfactant had the highest Phe removal, demonstrating the biosurfactant may enhance the bioavailability of Phe and the interaction with the microorganism. This study suggests that the EMR combined with biosurfactants can be used to enhance in situ bioremediation of PAH-contaminated soils. PMID:26683200

  7. A combination of electrokinetics and Pd/Fe PRB for the remediation of pentachlorophenol-contaminated soil.

    PubMed

    Li, Zhirong; Yuan, Songhu; Wan, Jinzhong; Long, Huayun; Tong, Man

    2011-06-01

    Electrokinetic (EK) remediation of pentachlorophenol (PCP)-contaminated soil is difficult because PCP dissociates at different pH values along soil column and shows different transport behaviors near anode and cathode. In the present study, a permeable reactive barrier (PRB) filled with reactive Pd/Fe particles was installed between anode and cathode to reach the dechlorination of PCP during its EK movement. When PRB was installed at the position of 0.3 (normalized distance from anode), PCP in the section from anode to PRB could transport through PRB, while PCP in the section from cathode to PRB was accumulated near PRB. PCP was hardly dechlorinated by PRB wherein high pH was reached. When PRB was installed at the position of 0.5 and the pH in the PRB was decreased by periodical injection of HAc, 49% of PCP was removed, and 22.9% was recovered as phenol which was mostly collected in catholyte. The mechanism of PCP removal was proposed as the EK movement of PCP into the PRB compartment, the complete dechlorination of PCP to phenol by Pd/Fe in the PRB compartment, and the subsequent removal of phenol by electroosmosis. This study proved that the combination of electrokinetics and Pd/Fe PRB was effective for the remediation of PCP-contaminated soil. PMID:21470711

  8. A combination of electrokinetics and Pd/Fe PRB for the remediation of pentachlorophenol-contaminated soil

    NASA Astrophysics Data System (ADS)

    Li, Zhirong; Yuan, Songhu; Wan, Jinzhong; Long, Huayun; Tong, Man

    2011-06-01

    Electrokinetic (EK) remediation of pentachlorophenol (PCP)-contaminated soil is difficult because PCP dissociates at different pH values along soil column and shows different transport behaviors near anode and cathode. In the present study, a permeable reactive barrier (PRB) filled with reactive Pd/Fe particles was installed between anode and cathode to reach the dechlorination of PCP during its EK movement. When PRB was installed at the position of 0.3 (normalized distance from anode), PCP in the section from anode to PRB could transport through PRB, while PCP in the section from cathode to PRB was accumulated near PRB. PCP was hardly dechlorinated by PRB wherein high pH was reached. When PRB was installed at the position of 0.5 and the pH in the PRB was decreased by periodical injection of HAc, 49% of PCP was removed, and 22.9% was recovered as phenol which was mostly collected in catholyte. The mechanism of PCP removal was proposed as the EK movement of PCP into the PRB compartment, the complete dechlorination of PCP to phenol by Pd/Fe in the PRB compartment, and the subsequent removal of phenol by electroosmosis. This study proved that the combination of electrokinetics and Pd/Fe PRB was effective for the remediation of PCP-contaminated soil.

  9. Micro-column plasma emission liquid chromatograph

    DOEpatents

    Gay, Don D.

    1984-01-01

    In a direct current plasma emission spectrometer for use in combination with a micro-column liquid chromatograph, an improved plasma source unit. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

  10. Flow in a metal hydride chromatographic column

    SciTech Connect

    Nichols, G.S.

    1990-01-01

    The flow of hydrogen isotopes in a metal hydride chromatographic column is calculated by a one-dimensional finite difference method. The Ergun equation is used to define the gas flow; and equilibrium pressure isotherms are used to define the column holdup. Solid phase loadings are shown to move as a wave front on absorption, but remain more uniform on desorption. 3 refs., 4 figs.

  11. Rotating annular chromatograph for continuous metal separations and recovery

    SciTech Connect

    Begovich, J.M.; Sisson, W.G.

    1981-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. By continuously introducing the feed material to be separated at a stationary point at the top of the bed and eluent everywhere else around the annulus, elution chromatography occurs. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence, the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effect of annulus width and diameter has recently been studied using the same device with a 50.8-mm-wide annulus and another 0.6-m-long chromatograph with an 89-mm diameter and annulus widths of 6.4, 12.7, and 22.2 mm. These columns have been constructed of Plexiglas and typically operate at a gauge pressure of 175 kPa. To further study the effect of size and pressure, a new 445-mm-diam by 1-m-long column with a 31.8-mm-wide annulus has been fabricated. Its metal construction allows preparative-scale operation with a wide variety of liquids at pressures to 1.3 MPa. Three metal recovery systems have been explored: (1) separation of iron and aluminum in ammonium sulfate-sulfuric acid solutions; (2) separation of hafnium from zirconium in sulfuric acid solutions; and (3) the separation of copper, nickel, and cobalt in ammonium carbonate solutions. This last system simulates the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. It has been studied, using similar conditions, on each of the chromatographs, and the results demonstrate the effect of column dimensions on the quality and quantity of the separation. 8 figures, 1 table.

  12. Micelle to trapping solution stacking in micellar electrokinetic chromatography.

    PubMed

    Liu, Lihong; Deng, Xinxian; Chen, Xingguo

    2010-01-01

    An analytical strategy micelle to trapping solution stacking (MSS) was developed in acidic buffer in micellar electrokinetic chromatography (MEKC). The stacking mechanism is based on the transport, release, capturing of molecules bound to micelle carriers that are made to collapse into trapping solution (TS) to serve as the medium to contain and stacking the analytes. Tetrandrine and fangchinoline were selected as model mixture using sodium dodecyl sulfate (SDS) micelles as carrier to demonstrate this stacking method. The experiments by MSS-MEKC were carried out and further compared with those by normal MEKC. The results reveal that 113-123-fold improvements in the detection sensitivity was obtained for the analytes, and separation and determination of tetrandrine and fangchinoline in Stephaniae tetrandrae S. Moore and Fengtongan capsules were finished under optimum conditions using the sample matrix containing 8.0mM SDS and TS containing 50mM H(3)PO(4)-55% (v/v) ethanol. PMID:19945115

  13. Acupuncture Sample Injection for Microchip Capillary Electrophoresis and Electrokinetic Chromatography.

    PubMed

    Ha, Ji Won; Hahn, Jong Hoon

    2016-05-01

    A simple nanoliter-scale injection technique was developed for polydimethylsiloxane (PDMS) microfluidic devices to form the well-defined sample plugs in microfluidic channels. Sample injection was achieved by performing acupuncture on a channel with a needle and applying external pressure to a syringe. This technique allowed us to achieve reproducible injection of a 3-nL segment into a microchannel for PDMS microchip-based capillary electrophoresis (CE). Capillary zone electrophoresis (CZE) and capillary electrochromatography (CEC) with bead packing were successfully performed by applying a single potential in the most simplified straight channel. The advantages of this acupuncture injection over the electrokinetic injection in microchip CE include capability of minimizing sample loss and voltage control hardware, capability of serial injections of different sample solutions into a same microchannel, capability of injecting sample plugs into any position of a microchannel, independence on sample solutions during the loading step, and ease in making microchips due to the straight channel, etc. PMID:27056036

  14. Ferritization treatment of copper in soil by electrokinetic remediation.

    PubMed

    Kimura, Tomoyuki; Takase, Ken-Ichi; Terui, Norifumi; Tanaka, Shunitz

    2007-05-17

    The usefulness of the combined use of the electrokinetic (EK) remediation and a ferrite treatment zone (FTZ) was demonstrated for a treatment of the contaminated soil with heavy metal ions. Copper ions in contaminated soil were transferred into the FTZ by the EK technology and were ferritized in this system. The distribution of copper in a migration chamber after EK treatment with FTZ for 48h showed the large difference in the total and eluted concentration of copper. This indicated that copper ions transferred by EK into the FTZ were ferritized there with ferrite reagent in soil alkalified by EK process. The copper-ferrite compound, which was not dissolved with diluted acid, was retained in the FTZ and accumulated there. The ratio of the ferritized amount of copper against total copper was 92% in the EK process with FTZ after 48 h. PMID:17374444

  15. Electrokinetic treatment of firing ranges containing tungsten-contaminated soils.

    PubMed

    Braida, Washington; Christodoulatos, Christos; Ogundipe, Adebayo; Dermatas, Dimitris; O'Connor, Gregory

    2007-11-19

    Tungsten-based alloys and composites are being used and new formulations are being considered for use in the manufacturing of different types of ammunition. The use of tungsten heavy alloys (WHA) in new munitions systems and tungsten composites in small caliber ammunition could potentially release substantial amounts of this element into the environment. Although tungsten is widely used in industrial and military applications, tungsten's potential environmental and health impacts have not been thoroughly addressed. This necessitates the research and development of remedial technologies to contain and/or remove tungsten from soils that may serve as a source for water contamination. The current work investigates the feasibility of using electrokinetics for the remediation of tungsten-contaminated soils in the presence of other heavy metals of concern such as Cu and Pb with aim to removing W from the soil while stabilizing in situ, Pb and Cu. PMID:17686582

  16. Entropic Electrokinetics: Recirculation, Particle Separation, and Negative Mobility

    NASA Astrophysics Data System (ADS)

    Malgaretti, Paolo; Pagonabarraga, Ignacio; Rubi, J. Miguel

    2014-09-01

    We show that when particles are suspended in an electrolyte confined between corrugated charged surfaces, electrokinetic flows lead to a new set of phenomena such as particle separation, mixing for low-Reynolds micro- and nanometric devices, and negative mobility. Our analysis shows that such phenomena arise, for incompressible fluids, due to the interplay between the electrostatic double layer and the corrugated geometrical confinement and that they are magnified when the width of the channel is comparable to the Debye length. Our characterization allows us to understand the physical origin of such phenomena, therefore, shedding light on their possible relevance in a wide variety of situations ranging from nano- and microfluidic devices to biological systems.

  17. Entropic electrokinetics: recirculation, particle separation, and negative mobility.

    PubMed

    Malgaretti, Paolo; Pagonabarraga, Ignacio; Rubi, J Miguel

    2014-09-19

    We show that when particles are suspended in an electrolyte confined between corrugated charged surfaces, electrokinetic flows lead to a new set of phenomena such as particle separation, mixing for low-Reynolds micro- and nanometric devices, and negative mobility. Our analysis shows that such phenomena arise, for incompressible fluids, due to the interplay between the electrostatic double layer and the corrugated geometrical confinement and that they are magnified when the width of the channel is comparable to the Debye length. Our characterization allows us to understand the physical origin of such phenomena, therefore, shedding light on their possible relevance in a wide variety of situations ranging from nano- and microfluidic devices to biological systems. PMID:25279646

  18. Electrokinetic Hydrogen Generation from Liquid WaterMicrojets

    SciTech Connect

    Duffin, Andrew M.; Saykally, Richard J.

    2007-05-31

    We describe a method for generating molecular hydrogen directly from the charge separation effected via rapid flow of liquid water through a metal orifice, wherein the input energy is the hydrostatic pressure times the volume flow rate. Both electrokinetic currents and hydrogen production rates are shown to follow simple equations derived from the overlap of the fluid velocity gradient and the anisotropic charge distribution resulting from selective adsorption of hydroxide ions to the nozzle surface. Pressure-driven fluid flow shears away the charge balancing hydronium ions from the diffuse double layer and carries them out of the aperture. Downstream neutralization of the excess protons at a grounded target electrode produces gaseous hydrogen molecules. The hydrogen production efficiency is currently very low (ca. 10-6) for a single cylindrical jet, but can be improved with design changes.

  19. Continuous-flow Electrokinetic Particle Separation in a Bifurcating Microchannel

    NASA Astrophysics Data System (ADS)

    Li, Di; Lu, Xinyu; Xuan, Xiangchun

    Separating particles from a heterogeneous mixture is important and necessary in many engineering and biomedical applications. Electrokinetic flow-based continuous particle separation has so far been realized primarily by the use of particle dielectrophoresis induced in constricted and/or curved microchannels. We demonstrate in this talk that particles can be continuously separated by size when passing through a bifurcating microchannel. This sheathless label-free separation relies on the wall-induced electrical lift force that acts to focus particles to the center of the main-branch and deflect them to size-dependent flow paths in the two side-branches. We also develop a numerical model to predict and understand this separation.

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

    PubMed

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

    2013-07-01

    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. PMID:23712291

  1. Electrokinetic-enhanced phytoremediation of soils: status and opportunities.

    PubMed

    Cameselle, Claudio; Chirakkara, Reshma A; Reddy, Krishna R

    2013-10-01

    Phytoremediation is a sustainable process in which green plants are used for the removal or elimination of contaminants in soils. Both organic and inorganic contaminants can be removed or degraded by growing plants by several mechanisms, namely phytoaccumulation, phytostabilization, phytodegradation, rhizofiltration and rhizodegradation. Phytoremediation has several advantages: it can be applied in situ over large areas, the cost is low, and the soil does not undergo significant damages. However, the restoration of a contaminated site by phytoremediation requires a long treatment time since the remediation depends on the growth and the biological cycles of the plant. It is only applicable for shallow depths within the reach of the roots, and the remediation efficiency largely depends on the physico-chemical properties of the soil and the bioavailability of the contaminants. The combination of phytoremediation and electrokinetics has been proposed in an attempt to avoid, in part, the limitations of phytoremediation. Basically, the coupled phytoremediation-electrokinetic technology consists of the application of a low intensity electric field to the contaminated soil in the vicinity of growing plants. The electric field may enhance the removal of the contaminants by increasing the bioavailability of the contaminants. Variables that affect the coupled technology are: the use of AC or DC current, voltage level and mode of voltage application (continuous or periodic), soil pH evolution, and the addition of facilitating agents to enhance the mobility and bioavailability of the contaminants. Several technical and practical challenges still remain that must be overcome through future research for successful application of this coupled technology at actual field sites. PMID:23835413

  2. Field application of electrokinetic remediation for multi-metal contaminated paddy soil using two-dimensional electrode configuration.

    PubMed

    Kim, Woo-Seung; Jeon, Eun-Ki; Jung, Ji-Min; Jung, Hong-Bae; Ko, Sung-Hwan; Seo, Chang-Il; Baek, Kitae

    2014-03-01

    In this study, we evaluated the feasibility of in situ electrokinetic remediation for arsenic (As)-, copper (Cu)-, and lead (Pb)-contaminated soil, in a pilot-scale field application with two-dimensional electrode configurations. Square and hexagonal configurations with different electrode spacing, 1 m and 2 m, were investigated under a constant 100 V. A square configuration with electrode spacing of 2 m removed 61.5 % of As, 11.4 % of Cu, and 0.9 % of Pb, respectively, and a hexagonal configuration with the same spacing showed a higher removal efficiency in top (59 % of As, 0-0.5 m) and middle (53 % of As, 0.5-1.0 m) layers, but much lower removal efficiency in the bottom layer (1-1.5 m), which was thought to be due to groundwater flow through periodic rise and fall of tides. Fractionation analysis showed that As bound to Fe-Mn oxyhydroxide was the main form of As removed by the electrokinetic process. The two-dimensional configuration wasted less electrical energy by Joule heating, and required fewer electrode installations, compared to the one-dimensional electrode configuration. PMID:24338001

  3. Application of capillary electrophoresis with electrokinetic supercharging and sweeping for the on-line preconcentration of phenolic acids.

    PubMed

    Lin, Yi-Hui; Huang, Hsin-Chieh; Hsu, Wan-Ling

    2015-09-01

    Phenolic acids are natural antioxidants. Many studies have confirmed that these compounds can reduce the risk of developing chronic diseases such as diabetes, cardiovascular diseases, and certain cancers. In this work, we developed a rapid and efficient capillary electrophoresis method with an on-line preconcentration technique that could be used to simultaneously analyze 10 commonly found phenolic acids in plants. Briefly, phosphate buffer solution (pH 2) was filled into an uncoated fused silica capillary as the leading electrolyte, and then samples which were prepared in borate buffer (as the terminating ion) were loaded by electrokinetic injection (-10 kV, 900 s). After sample injection, both ends of the capillary were switched to the vial containing phosphate buffer with sodium dodecyl sulfate. The separation was then performed in micellar electrokinetic chromatography (MEKC) mode at -20 kV. During the method validation, the correlation coefficient of the regression curve was measured as greater than 0.997 and the relative standard deviation and relative error were lower than 9.63 % and 4.7 %, respectively. The limits of detection (LODs, S/N = 3) of these 10 analytes ranged from 0.01 to 2.5 ng/mL. Compared with the conventional capillary zone electrophoresis (CZE) method, the sensitivity for the analytes could be increased up to 25,000-fold. The method that we developed here was applied successfully to the detection of phenolic acids in fruit juices. PMID:26159571

  4. Rapid (<5 min) Identification of Pathogen in Human Blood by Electrokinetic Concentration and Surface-Enhanced Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    I-Fang Cheng; Chang, Hsien-Chang; Chen, Tzu-Ying; Hu, Chenming; Yang, Fu-Liang

    2013-08-01

    This study reports a novel microfluidic platform for rapid and long-ranged concentration of rare-pathogen from human blood for subsequent on-chip surface-enhanced Raman spectroscopy (SERS) identification/discrimination of bacteria based on their detected fingerprints. Using a hybrid electrokinetic mechanism, bacteria can be concentrated at the stagnation area on the SERS-active roughened electrode, while blood cells were excluded away from this region at the center of concentric circular electrodes. This electrokinetic approach performs isolation and concentration of bacteria in about three minutes; the density factor is increased approximately a thousand fold in a local area of ~5000 μm2 from a low bacteria concentration of 5 × 103 CFU/ml. Besides, three genera of bacteria, S. aureus, E. coli, and P. aeruginosa that are found in most of the isolated infections in bacteremia were successfully identified in less than one minute on-chip without the use of any antibody/chemical immobilization and reaction processes.

  5. Field application of electrokinetic remediation for multi-metal contaminated paddy soil using two-dimensional electrode configuration.

    PubMed

    Kim, Woo-Seung; Jeon, Eun-Ki; Jung, Ji-Min; Jung, Hong-Bae; Ko, Sung-Hwan; Seo, Chang-Il; Baek, Kitae

    2014-03-01

    In this study, we evaluated the feasibility of in situ electrokinetic remediation for arsenic (As)-, copper (Cu)-, and lead (Pb)-contaminated soil, in a pilot-scale field application with two-dimensional electrode configurations. Square and hexagonal configurations with different electrode spacing, 1 m and 2 m, were investigated under a constant 100 V. A square configuration with electrode spacing of 2 m removed 61.5 % of As, 11.4 % of Cu, and 0.9 % of Pb, respectively, and a hexagonal configuration with the same spacing showed a higher removal efficiency in top (59 % of As, 0-0.5 m) and middle (53 % of As, 0.5-1.0 m) layers, but much lower removal efficiency in the bottom layer (1-1.5 m), which was thought to be due to groundwater flow through periodic rise and fall of tides. Fractionation analysis showed that As bound to Fe-Mn oxyhydroxide was the main form of As removed by the electrokinetic process. The two-dimensional configuration wasted less electrical energy by Joule heating, and required fewer electrode installations, compared to the one-dimensional electrode configuration.

  6. Ultraviolet-photodiode array and high-performance liquid chromatographic/mass spectrometric studies on forced degradation behavior of glibenclamide and development of a validated stability-indicating method.

    PubMed

    Bansal, Gulshan; Singh, Manjeet; Jindal, Kaur Chand; Singh, Saranjit

    2008-01-01

    A forced degradation study on glibenclamide was performed under conditions of hydrolysis, oxidation, dry heat, and photolysis and a high-performance column liquid chromatographic-ultraviolet (HPLC-UV) method was developed to study degradation behavior of the drug under the forced conditions. The degradation products formed under different forced conditions were characterized through isolation and subsequent infrared/nuclear magnetic resonance/mass spectral analyses, or through HPLC/mass spectrometric (HPLC/MS) studies. The drug degraded in 0.1 M HCI and water at 85 degrees C to a major degradation product, 5-chloro-2-methoxy-N-2-(4-sulfamoylphenyl)ethyl]benzamide (III), and to a minor product, 1-cyclohexyl-3-[[4-(2-aminoethyl)-phenyl]sulfonyl]urea (IV). Upon prolonged heating in the acid, the minor product IV disappeared, resulting in formation of 5-chloro-2-methoxy-benzoic acid (II) and an unidentified product (I). Heating of the drug in 0.1 M NaOH at 85 degrees C yielded II and IV as the major products and I and III as the minor products. The drug and the degradation products formed under different conditions were optimally resolved on a C18 column using ammonium acetate buffer (0.025 M, pH 3.5)-acetonitrile (45 + 55) mobile phase at a flow rate of 0.6 mL/min, with detection at 230 nm. The method was validated for linearity, precision, accuracy, and specificity. Limit of detection (LOD) and limit of quantitation (LOQ) values were also determined. The method could be successfully applied for simultaneous quantification of glibenclamide and the major product, III. The response of the method was linear in a narrow [0.4-10 micro/mL, correlation coefficient (r2) = 0.9982] and a wide (0.4-500 microg/mL, r2 = 0.9993) concentration range for glibenclamide, and in the concentration range of 0.025-50 microg/mL (r2 = 0.9998) for III. The method proved to be precise and accurate for both glibenclamide and III. It was specific for the drug and also selective for each

  7. Electrokinetic and optical control of bacterial microrobots

    NASA Astrophysics Data System (ADS)

    Steager, Edward B.; Selman Sakar, Mahmut; Kim, Dal Hyung; Kumar, Vijay; Pappas, George J.; Kim, Min Jun

    2011-03-01

    One of the great challenges in microscale science and engineering is the independent manipulation of cells and man-made objects on the micron scale. For such work, motile microorganisms are integrated with engineered systems to construct microbiorobots (MBRs). MBRs are negative photosensitive epoxy (SU-8) microfabricated structures with typical feature sizes ranging from 1 to 100 µm coated with a monolayer of swarmer cells of the bacterium Serratia marcescens. The adherent cells naturally coordinate to propel the microstructures in fluidic environments. In this study, ultraviolet light is used to control rotational motion and direct current electric fields are used to control the two-dimensional movement of MBRs. They are steered in a fully automated fashion using computer-controlled visual servoing, used to transport and manipulate micron-sized objects, and employed as cell-based biosensors. This work is a step toward in vitro mechanical or chemical manipulation of cells as well as controlled assembly of microcomponents.

  8. Chromatographic removal and heat inactivation of hepatitis A virus during manufacture of human albumin.

    PubMed

    Adcock, W L; MacGregor, A; Davies, J R; Hattarki, M; Anderson, D A; Goss, N H

    1998-08-01

    CSL Limited, an Australian biopharmaceutical company, has recently converted its method of manufacture for human albumin from a traditional Cohn-ethanol fractionation method to a method employing chromatographic techniques. Studies were undertaken to determine the efficiency of the chromatographic and pasteurization steps used in the manufacture of Albumex(R) (CSL's trade name for albumin) in removing and inactivating the potential viral contaminant, hepatitis A virus (HAV). The manufacturing process for Albumex(R) includes three chromatographic steps, two of which are ion-exchange steps (DEAE-Sepharose(R) Fast Flow and CM-Sepharose(R) Fast Flow) and the third is a gel-filtration step (Sephacryl(R) S200 HR). The final stage of the Albumex(R) process involves a bulk pasteurization step where product is held at 60 degrees C for 10 h. HAV partitioning experiments on the DEAE-Sepharose(R) FF and CM-Sepharose(R) FF ion-exchange and Sephacryl(R) S200 HR gel-filtration columns were performed with scaled-down models of the production-scale chromatographic Albumex(R) process. Production samples collected before each of the chromatographic steps were spiked with HAV and processed through each of the scaled-down chromatographic columns. Samples collected during processing were assayed and the log10 reduction factors calculated. Inactivation kinetics of HAV were examined during the pasteurization of Albumex(R) 5 and 20 [5% and 20% (w/v) albumin solutions] held at 60 degrees C for 10 h. Log10 reductions for HAV through the DEAE-Sepharose(R) FF, CM-Sepharose(R) FF and Sephacryl(R) S200 HR chromatographic columns were 5.3, 1.5 and 4.2 respectively, whereas a 4.4 and a greater than 3.9 log10 reduction in HAV in Albumex(R) 5 and 20 respectively were achieved during pasteurization.

  9. The Monte Carlo validation framework for the discriminant partial least squares model extended with variable selection methods applied to authenticity studies of Viagra® based on chromatographic impurity profiles.

    PubMed

    Krakowska, B; Custers, D; Deconinck, E; Daszykowski, M

    2016-02-01

    The aim of this work was to develop a general framework for the validation of discriminant models based on the Monte Carlo approach that is used in the context of authenticity studies based on chromatographic impurity profiles. The performance of the validation approach was applied to evaluate the usefulness of the diagnostic logic rule obtained from the partial least squares discriminant model (PLS-DA) that was built to discriminate authentic Viagra® samples from counterfeits (a two-class problem). The major advantage of the proposed validation framework stems from the possibility of obtaining distributions for different figures of merit that describe the PLS-DA model such as, e.g., sensitivity, specificity, correct classification rate and area under the curve in a function of model complexity. Therefore, one can quickly evaluate their uncertainty estimates. Moreover, the Monte Carlo model validation allows balanced sets of training samples to be designed, which is required at the stage of the construction of PLS-DA and is recommended in order to obtain fair estimates that are based on an independent set of samples. In this study, as an illustrative example, 46 authentic Viagra® samples and 97 counterfeit samples were analyzed and described by their impurity profiles that were determined using high performance liquid chromatography with photodiode array detection and further discriminated using the PLS-DA approach. In addition, we demonstrated how to extend the Monte Carlo validation framework with four different variable selection schemes: the elimination of uninformative variables, the importance of a variable in projections, selectivity ratio and significance multivariate correlation. The best PLS-DA model was based on a subset of variables that were selected using the variable importance in the projection approach. For an independent test set, average estimates with the corresponding standard deviation (based on 1000 Monte Carlo runs) of the correct

  10. Serum 25-hydroxyvitamin D assay. Evalution of chromatographic and non-chromatographic procedures.

    PubMed

    Skinner, R K; Wills, M R

    1977-11-01

    A competitive protein binding assay for serum 25-hydroxyvitamin D is described in which normal human serum is used as the source of binding protein. A serum sample is extracted with diethyl ether/methanol and then chromatographed using silica gel. Validation of the method is reported. Silica gel chromatography is compared with LH20 chromatography. The method is also compared with extraction techniques using diethyl ether and ethanol without subsequent chromatography. It is concluded that chromatography with either silica gel or LH20 is essential. The non-chromatographic methods investigated, in addition to giving much higher values than chromatographic methods, did not meet validation requirements with respect to accuracy and behaviour of samples on dilution.

  11. Transesterification of propylene glycol methyl ether in chromatographic reactors using anion exchange resin as a catalyst.

    PubMed

    Oh, Jungmin; Sreedhar, Balamurali; Donaldson, Megan E; Frank, Timothy C; Schultz, Alfred K; Bommarius, Andreas S; Kawajiri, Yoshiaki

    2016-09-30

    Reactive chromatography using an anion exchange resin is proposed for a transesterification reaction of propylene glycol methyl ether (DOWANOL™ PM) with ethyl acetate to produce propylene glycol methyl ether acetate (DOWANOL™ PMA). This reaction is studied in batch and chromatographic reactors catalyzed by an anion exchange resin. Several anion exchange resins are tested and compared based on the performance of resin as an adsorbent and a catalyst. A chromatographic column is packed with a selected catalyst, AMBERLITE™ IRA904, and both reaction and chromatographic elution are studied at different temperatures and feed concentrations. The resulting chromatograms are fitted to a mathematical model to obtain adsorption equilibrium and reaction kinetic parameters by the inverse method. Compared to esterification investigated in a previous study, transesterification has advantages such as a higher conversion at lower temperature and easy removal of the byproduct which may lead to higher productivity. Deactivation of anion exchange resins is observed and potential solutions are suggested.

  12. Transesterification of propylene glycol methyl ether in chromatographic reactors using anion exchange resin as a catalyst.

    PubMed

    Oh, Jungmin; Sreedhar, Balamurali; Donaldson, Megan E; Frank, Timothy C; Schultz, Alfred K; Bommarius, Andreas S; Kawajiri, Yoshiaki

    2016-09-30

    Reactive chromatography using an anion exchange resin is proposed for a transesterification reaction of propylene glycol methyl ether (DOWANOL™ PM) with ethyl acetate to produce propylene glycol methyl ether acetate (DOWANOL™ PMA). This reaction is studied in batch and chromatographic reactors catalyzed by an anion exchange resin. Several anion exchange resins are tested and compared based on the performance of resin as an adsorbent and a catalyst. A chromatographic column is packed with a selected catalyst, AMBERLITE™ IRA904, and both reaction and chromatographic elution are studied at different temperatures and feed concentrations. The resulting chromatograms are fitted to a mathematical model to obtain adsorption equilibrium and reaction kinetic parameters by the inverse method. Compared to esterification investigated in a previous study, transesterification has advantages such as a higher conversion at lower temperature and easy removal of the byproduct which may lead to higher productivity. Deactivation of anion exchange resins is observed and potential solutions are suggested. PMID:27623064

  13. Multi-objective optimization of chromatographic rare earth element separation.

    PubMed

    Knutson, Hans-Kristian; Holmqvist, Anders; Nilsson, Bernt

    2015-10-16

    The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75 kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79 kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium. PMID:26375205

  14. Multi-objective optimization of chromatographic rare earth element separation.

    PubMed

    Knutson, Hans-Kristian; Holmqvist, Anders; Nilsson, Bernt

    2015-10-16

    The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75 kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79 kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium.

  15. Probing single biomolecules in solution using the anti-Brownian electrokinetic (ABEL) trap.

    PubMed

    Wang, Quan; Goldsmith, Randall H; Jiang, Yan; Bockenhauer, Samuel D; Moerner, W E

    2012-11-20

    Single-molecule fluorescence measurements allow researchers to study asynchronous dynamics and expose molecule-to-molecule structural and behavioral diversity, which contributes to the understanding of biological macromolecules. To provide measurements that are most consistent with the native environment of biomolecules, researchers would like to conduct these measurements in the solution phase if possible. However, diffusion typically limits the observation time to approximately 1 ms in many solution-phase single-molecule assays. Although surface immobilization is widely used to address this problem, this process can perturb the system being studied and contribute to the observed heterogeneity. Combining the technical capabilities of high-sensitivity single-molecule fluorescence microscopy, real-time feedback control and electrokinetic flow in a microfluidic chamber, we have developed a device called the anti-Brownian electrokinetic (ABEL) trap to significantly prolong the observation time of single biomolecules in solution. We have applied the ABEL trap method to explore the photodynamics and enzymatic properties of a variety of biomolecules in aqueous solution and present four examples: the photosynthetic antenna allophycocyanin, the chaperonin enzyme TRiC, a G protein-coupled receptor protein, and the blue nitrite reductase redox enzyme. These examples illustrate the breadth and depth of information which we can extract in studies of single biomolecules with the ABEL trap. When confined in the ABEL trap, the photosynthetic antenna protein allophycocyanin exhibits rich dynamics both in its emission brightness and its excited state lifetime. As each molecule discontinuously converts from one emission/lifetime level to another in a primarily correlated way, it undergoes a series of state changes. We studied the ATP binding stoichiometry of the multi-subunit chaperonin enzyme TRiC in the ABEL trap by counting the number of hydrolyzed Cy3-ATP using stepwise

  16. ION-EXCLUSION CHROMATOGRAPHIC DETERMINATION OF CARBOXYLIC ACIDS USED TO SUPPORT THE MICROBIALLY MEDIATED REDUCTIVE DECHLORINATION OF TETRACHLOROETHENE

    EPA Science Inventory

    An analytical method was developed for the determination of lactic acid, formic acid, acetic acid, propionic acid, and butyric acid in environmental microcosm samples using ion-exclusion chromatography. The chromatographic behavior of various eluents was studied to determine the ...

  17. High pressure liquid chromatographic gradient mixer

    DOEpatents

    Daughton, Christian G.; Sakaji, Richard H.

    1985-01-01

    A gradient mixer which effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum "band-broadening".

  18. High-pressure liquid chromatographic gradient mixer

    DOEpatents

    Daughton, C.G.; Sakaji, R.H.

    1982-09-08

    A gradient mixer effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum band-broadening.

  19. Hand-held multiple system gas chromatograph

    DOEpatents

    Yu, Conrad M.

    2001-01-01

    A multiple parallel hand-held gas chromatograph (GC) system which includes several independent GCs. Each independent GC has its own injector, separation column, detector and oven and the GCs are mounted in a light weight hand-held assembly. Each GC operates independently and simultaneously. Because of different coatings in different separation columns, different retention times for the same gas will be measured. Thus, for a GC system with multiple parallel GCs, the system can measure, in a short period, different retention times and provide a cross-reference in the determination of the measured gas and to become a two-dimensional system for direct field use.

  20. Design criteria for soil cleaning operations in electrokinetic remediation: hydrodynamic aspects in a cylindrical geometry.

    PubMed

    Oyanader, Mario A; Arce, Pedro; Dzurik, Andrew

    2005-08-01

    The applications of electrokinetics embrace a large family of important industrial, pharmaceutical, biomedical, and environmental applications. Processes such as separation, drug delivery, soil remediation, and others constitute alist of applications where electrical fields are used to induce the movement of solute species. Different transport driving forces participate in the motion of the solute. In the particular case of soil remediation, the electromechanisms may compete with buoyancy and advection, promoting distinct flow regimes. As a rule of thumb, some of the earlier applications of electrokinetic phenomena, mainly in the area of electrophoresis, neglected this competition, and therefore the hydrodynamics of the systems was considered simpler. The nature of the process in soil, a porous media, calls for a different approach and is in need of further analysis of the complete map of collaborating driving forces. The identification and analysis of the characteristic flow regimes may lead to important guidelines for improving the separation, avoiding the mixing, and more efficient cleaning in a given application. In this contribution, using a cylindrical capillary model, the basic aspects of the behavior of the system are captured. A differential model is formulated using simplifying assumptions, maintaining the mathematical aspects to a minimum level, and a solution is presented for the different fields, i.e., the temperature and the velocity. Based on the selection of values of the parameter space, several limiting cases and flow regimes are presented and discussed. Implications for the design of devices and cleaning strategies are also included. Needs for further research are identified. The main idea behind the study is to obtain a qualitative and semiquantitative description of the different flow regimes inside the channel. This information is useful to identify further aspects of the investigation and delineate a systematic approach for a more rigorous

  1. Enhanced electrokinetic remediation of lead-contaminated soil by complexing agents and approaching anodes.

    PubMed

    Zhang, Tao; Zou, Hua; Ji, Minhui; Li, Xiaolin; Li, Liqiao; Tang, Tang

    2014-02-01

    Optimizing process parameters that affect the remediation time and power consumption can improve the treatment efficiency of the electrokinetic remediation as well as determine the cost of a remediation action. Lab-scale electrokinetic remediation of Pb-contaminated soils was investigated for the effect of complexant ethylenediaminetetraacetic acid (EDTA) and acetic acid and approaching anode on the removal efficiency of Pb. When EDTA was added to the catholyte, EDTA dissolved insoluble Pb in soils to form soluble Pb-EDTA complexes, increasing Pb mobility and accordingly removal efficiency. The removal efficiency was enhanced from 47.8 to 61.5 % when the EDTA concentration was increased from 0.1 to 0.2 M, showing that EDTA played an important role in remediation. And the migration rate of Pb was increased to 72.3 % when both EDTA and acetic acid were used in the catholyte. The "approaching anode electrokinetic remediation" process in the presence of both EDTA and acetic acid had a higher Pb-removal efficiency with an average efficiency of 83.8 %. The efficiency of electrokinetic remediation was closely related to Pb speciation. Exchangeable and carbonate-bounded Pb were likely the forms which could be removed. All results indicate that the approaching anode method in the presence of EDTA and acetic acid is an advisable choice for electrokinetic remediation of Pb-contaminated soil. PMID:24203258

  2. Nanodiamond-Decorated Silica Spheres as a Chromatographic Material.

    PubMed

    Xue, Zuqin; Vinci, John C; Colón, Luis A

    2016-02-17

    Nanodiamond (ND) particles (∼5 nm), obtained from detonation soot, were oxidized and/or thermally hydrogenated. Both, the non-hydrogenated and hydrogenated ND particles were successfully coupled to the surface of micrometer-size organo-silica particles. A thin layer of nanodiamonds (NDs) decorating the surface of the organo-silica particles was visible on transmission electron microscopy (TEM) images. X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) were used to characterize the NDs prior to coupling and to confirm attachment onto the organo-silica particles. Both, ultraviolet (UV) radiation and a chemical initiator were proved to be effective radical initiators for the ND-silica coupling reaction, although for scale-up purposes the chemical initiation was more advantageous to produce the ND-silica composite. Commercially available nanodiamond primary particles were also coupled to the surface of silica particles. The ND-containing silica particles were packed into chromatographic columns to study their initial feasibility as adsorbent material for liquid chromatography. The organo-silica particles decorated with hydrogenated NDs were shown to possess reversed phase type (i.e., hydrophobic) behavior toward the probe compounds, whereas silica particles decorated with the non-hydrogenated NDs showed polar (i.e., hydrophilic) interactions, both under liquid chromatographic conditions. PMID:26790050

  3. Micro and nanoscale electrochemical systems for reagent generation, coupled electrokinetic transport and enhanced detection

    NASA Astrophysics Data System (ADS)

    Contento, Nicholas M.

    Chemical analysis is being performed in devices operated at ever decreasing length scales in order to harness the fundamental benefits of micro and nanoscale phenomena while minimizing operating footprint and sample size. The advantages of moving traditional sample or chemical processing steps (e.g. separation, detection, and reaction) into micro- and nanofluidic devices have been demonstrated, and they arise from the relatively rapid rates of heat and mass transport at small length scales. The use of electrochemical methods in micro/nanoscale systems to control and improve these processes holds great promise. Unfortunately, much is still not understood about the coupling of multiple electrode driven processes in a confined environment nor about the fundamental changes in device performance that occur as geometries approach the nanoscale regime. At the nanoscale a significant fraction of the sample volume is in close contact with the device surface, i.e. most of the sample is contained within electronic or diffusion layers associated with surface charge or surface reactions, respectively. The work presented in this thesis aims to understand some fundamental different behaviors observed in micro/nanofluidic structures, particularly those containing one or more embedded, metallic electrode structures. First, a quantitative method is devised to describe the impact of electric fields on electrochemistry in multi-electrode micro/nanofluidic systems. Next the chemical manipulation of small volumes (≤ 10-13 L) in micro/nanofluidic structures is explored by creating regions of high pH and high dissolved gas (H 2) concentration through the electrolysis of H2O. Massively parallel arrays of nanochannel electrodes, or embedded annular nanoband electrodes (EANEs), are then studied with a focus on achieving enhanced signals due to coupled electrokinetic and electrochemical effects. In EANE devices, electroosmotic flow results from the electric field generated between the

  4. Separation of hydrophobic polymer additives by microemulsion electrokinetic chromatography.

    PubMed

    Hilder, E F; Klampfl, C W; Buchberger, W; Haddad, P R

    2001-07-13

    Microemulsion electrokinetic chromatography (MEEKC) has been applied to the separation of some phenolic antioxidants [Irganox 1024, Irganox 1035, Irganox 1076, Irganox 1010, Irganox 1330, Irgafos 138, Irganox 168 and 2,6-di-tert.-butyl-4-methylphenol (BHT)]. Due to the extremely hydrophobic nature of these analytes, they could not be separated using standard MEEKC conditions and two alternative approaches were investigated. Using an acidic buffer (phosphate, pH 2.5) to effectively suppress the electroosmotic flow, the addition of 2-propanol to the aqueous phase of the microemulsion buffer to improve partitioning of the analytes, and a negative separation voltage, separation of five of the analytes in under 10 min was possible. The second approach, using a basic buffer (borate, pH 9.2) and a positive separation voltage resulted in complete resolution of all eight analytes. A mixed surfactant system comprising the anionic sodium dodecyl sulfate (SDS) and neutral Brij 35 was used to reduce the overall charge and with it the mobility of the droplets, and hence the separation time. Using an optimised MEEKC buffer consisting of 2.25% (w/w) SDS, 0.75% (w/w) Brij 35, 0.8% (w/w) n-octane, 6.6% (w/w) 1-butanol, 25% (w/w) 2-propanol and 64.6% (w/w) 10 mM borate buffer (pH 9.2) the eight target analytes were baseline separated in under 25 min. For these analytes, MEEKC was found to be superior to micellar electrokinetic chromatography in every respect. Specifically, the solubility of the analytes was better, the selectivity was more favourable, the analysis time was shorter and the separation efficiency was up to 72% higher when using the MEEKC method. Detection limits from 5.4 to 26 microg/ml were obtained and the calibration plot was linear over more than one order of magnitude. The optimised method could be applied to the determination of Irganox 1330 and Irganox 1010 in polypropylene.

  5. Removal of oxyfluorfen from spiked soils using electrokinetic soil flushing with the surrounding arrangements of electrodes.

    PubMed

    Risco, C; Rubí-Juárez, H; Rodrigo, S; López-Vizcaíno, R; Saez, C; Cañizares, P; Barrera-Díaz, C; Navarro, V; Rodrigo, M A

    2016-07-15

    This work reports the results of a study in which the remediation of soil that undergoes an accidental discharge of oxyfluorfen is carried out by using electrokinetic soil flushing (EKSF). Two different electrode configurations were tested, consisting of several electrodes surrounding an electrode of different polarity (so-called 1A6C, one anode surrounded by six cathodes, and 1C6A, one cathode surrounded by six cathodes). A pilot plant scale was used (with a soil volume of 175dm(3)) to perform the studies. During the tests, different parameters were measured daily (flowrates, pH, electrical conductivity and herbicide concentration in different sampling positions). Furthermore, at the end of the test, a complete post-mortem analysis was carried out to obtain a 3-D map of the pollution, pH and electrical conductivity in the soil. The results demonstrate that electrode arrangement is a key factor for effective pollutant removal. In fact, the 1A6C configuration improves the removal rate by 41.3% versus the 27.0% obtained by the 1C6A configuration after a period of 35days. Finally, a bench mark comparison of this study of soil remediation polluted with 2,4-D allows for significant conclusions about the scale-up and full-scale application of this technology. PMID:27058128

  6. Versatile gas/particle ion chromatograph.

    PubMed

    Ullah, S M Rahmat; Takeuchi, Masaki; Dasgupta, Purnendu K

    2006-02-01

    A new, compact gas/particle ion chromatograph has been developed for measuring ionic constituents in PM2.5 (particulate matter of aerodynamic diameter < or = 2.5 microm) and water-soluble ionogenic gases. The instrument has separate sampling channels for gases and particles. In one, a membrane denuder collects soluble gases for preconcentration and analysis. In the other, a cyclone removes larger particles, a membrane denuder removes soluble gases, and a continuously wetted hydrophilic filter collects particles. A single, multiport, syringe pump handles liquid transport, and one conductivity detector measures anions and ammonium for both channels. Electrodialytically generated gradient hydroxide eluent permits 20 min chromatographic runs. Gas/particle samples are each collected for 40 min, butthe sampling intervals are staggered by 20 min. Liquid samples from the gas denuder and particle collector are aspirated and preconcentrated on sequential cation and anion concentrators and transferred respectively to an ammonia transfer device and an anion separation column. The flow configuration results in an ammonium peak before anion peaks in the chromatogram. The system measures ammonia, organic acids (such as acetic, formic, and oxalic acids), HCl, HONO, SO2, HNO3, and the corresponding ions in the aerosol phase. Low ng/m3 to sub-ng/m3 limits of detection (LODs) are attained for most common gases and particulate constituents, the LODs for gaseous SO2 to NH3 range, for example, from sub parts per trillion by volume (sub-pptv) to approximately 5 pptv.

  7. Versatile gas/particle ion chromatograph.

    PubMed

    Ullah, S M Rahmat; Takeuchi, Masaki; Dasgupta, Purnendu K

    2006-02-01

    A new, compact gas/particle ion chromatograph has been developed for measuring ionic constituents in PM2.5 (particulate matter of aerodynamic diameter < or = 2.5 microm) and water-soluble ionogenic gases. The instrument has separate sampling channels for gases and particles. In one, a membrane denuder collects soluble gases for preconcentration and analysis. In the other, a cyclone removes larger particles, a membrane denuder removes soluble gases, and a continuously wetted hydrophilic filter collects particles. A single, multiport, syringe pump handles liquid transport, and one conductivity detector measures anions and ammonium for both channels. Electrodialytically generated gradient hydroxide eluent permits 20 min chromatographic runs. Gas/particle samples are each collected for 40 min, butthe sampling intervals are staggered by 20 min. Liquid samples from the gas denuder and particle collector are aspirated and preconcentrated on sequential cation and anion concentrators and transferred respectively to an ammonia transfer device and an anion separation column. The flow configuration results in an ammonium peak before anion peaks in the chromatogram. The system measures ammonia, organic acids (such as acetic, formic, and oxalic acids), HCl, HONO, SO2, HNO3, and the corresponding ions in the aerosol phase. Low ng/m3 to sub-ng/m3 limits of detection (LODs) are attained for most common gases and particulate constituents, the LODs for gaseous SO2 to NH3 range, for example, from sub parts per trillion by volume (sub-pptv) to approximately 5 pptv. PMID:16509343

  8. Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

    DOEpatents

    Ramirez, A.L.; Cooper, J.F.; Daily, W.D.

    1996-02-27

    This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination. 1 fig.

  9. Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

    DOEpatents

    Ramirez, Abelardo L.; Cooper, John F.; Daily, William D.

    1996-01-01

    This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination.

  10. Electrostatic and electrokinetic contributions to the elastic moduli of a driven membrane

    NASA Astrophysics Data System (ADS)

    Lacoste, D.; Menon, G. I.; Bazant, M. Z.; Joanny, J. F.

    2009-03-01

    We discuss the electrostatic contribution to the elastic moduli of a cell or artificial membrane placed in an electrolyte and driven by a DC electric field. The field drives ion currents across the membrane, through specific channels, pumps or natural pores. In steady state, charges accumulate in the Debye layers close to the membrane, modifying the membrane elastic moduli. We first study a model of a membrane of zero thickness, later generalizing this treatment to allow for a finite thickness and finite dielectric constant. Our results clarify and extend the results presented by D. Lacoste, M. Cosentino Lagomarsino, and J.F. Joanny (EPL 77, 18006 (2007)), by providing a physical explanation for a destabilizing term proportional to k ⊥ 3 in the fluctuation spectrum, which we relate to a nonlinear (E2) electrokinetic effect called induced-charge electro-osmosis (ICEO). Recent studies of ICEO have focused on electrodes and polarizable particles, where an applied bulk field is perturbed by capacitive charging of the double layer and drives the flow along the field axis toward surface protrusions; in contrast, we predict “reverse” ICEO flows around driven membranes, due to curvature-induced tangential fields within a nonequilibrium double layer, which hydrodynamically enhance protrusions. We also consider the effect of incorporating the dynamics of a spatially dependent concentration field for the ion channels.

  11. Quantitative analysis of synthetic dyes in lipstick by micellar electrokinetic capillary chromatography.

    PubMed

    Desiderio, C; Marra, C; Fanali, S

    1998-06-01

    The separation of synthetic dyes, used as color additives in cosmetics, by micellar electrokinetic capillary chromatography (MEKC) is described in this study. The separation of seven dyes, namely eosine, erythrosine, cyanosine, rhodamine B, orange II, chromotrope FB and tartrazine has been achieved in about 3 min in an untreated fused silica capillary containing as background electrolyte a 25 mM tetraborate/phosphate buffer, pH 8.0, and 30 mM sodium dodecyl sulfate. The electrophoretic method exhibits precision and relatively high sensitivity. A detection limit (LOD, signal/noise = 3) in the range of 5-7.5 X 10(-7) M of standard compounds was recorded. Intra-day repeatability of all the studied dye determinations (8 runs) gave the following results (limit values), % standard deviation: 0.24-1.54% for migration time, 0.99-1.24% for corrected peak areas, 0.99-1.24% for corrected peak area ratio (analyte/internal standard) and 1.56-2.74% for peak areas. The optimized method was successfully applied to the analysis of a lipstick sample where eosine and cyanosine were present.

  12. Determination of food colorants by microemulsion electrokinetic chromatography.

    PubMed

    Huang, Hsi-Ya; Chuang, Chia-Ling; Chiu, Chen-Wen; Chung, Ming-Che

    2005-02-01

    A microemulsion electrokinetic chromatography (MEEKC) method was developed to analyze and detect eight food colorants (tartrazine, fast green FCF, brilliant blue FCF, allura red AC, indigo carmine, sunset yellow FCF, new coccine, and carminic acid), which are commonly used as food additives in various food products. The effects of sodium dodecyl sulfate (SDS) surfactant, organic modifier, cosurfactant, and oil were examined in order to optimize the separation. The amount of organic modifier (acetonitrile) and SDS surfactant were determined as apparent influences on the separation resolution while the type of oil and cosurfactant rarely affected the separation selectivity of the eight colorants. A highly efficient MEEKC separation method, where the eight colorants were separated with baseline resolution within 14 min, was achieved by using a microemulsion solution of pH 2.0 containing 3.31% SDS, 0.81% octane, 6.61% 1-butanol, and 10% acetonitrile. This optimal MEEKC method has a higher separation efficiency and similar detection limit when compared to conventional capillary electrophoresis (CE) method. Furthermore, a sample pretreatment is rarely needed when this MEEKC technique is used to analyze colorants in food products, whereas a suitable sample pretreatment (for example solid-phase extraction) has to be employed prior to CE separation in order to eliminate matrix interferences resulting from the constituents of the food sample. PMID:15669007

  13. Multiple electrokinetic actuators for feedback control of colloidal crystal size.

    PubMed

    Juárez, Jaime J; Mathai, Pramod P; Liddle, J Alexander; Bevan, Michael A

    2012-10-21

    We report a feedback control method to precisely target the number of colloidal particles in quasi-2D ensembles and their subsequent assembly into crystals in a quadrupole electrode. Our approach relies on tracking the number of particles within a quadrupole electrode, which is used in a real-time feedback control algorithm to dynamically actuate competing electrokinetic transport mechanisms. Particles are removed from the quadrupole using DC-field mediated electrophoretic-electroosmotic transport, while high-frequency AC-field mediated dielectrophoretic transport is used to concentrate and assemble colloidal crystals. Our results show successful control of the size of crystals containing 20 to 250 colloidal particles with less than 10% error. Assembled crystals are characterized by their radius of gyration, crystallinity, and number of edge particles, and demonstrate the expected size-dependent properties. Our findings demonstrate successful ensemble feedback control of the assembly of different sized colloidal crystals using multiple actuators, which has broad implications for control over nano- and micro- scale assembly processes involving colloidal components.

  14. Oscillating laminar electrokinetic flow in infinitely extended circular microchannels.

    PubMed

    Bhattacharyya, A; Masliyah, J H; Yang, J

    2003-05-01

    This article addresses the problem of oscillating laminar electrokinetic liquid flow in an infinitely extended circular microchannel. Based on the Debye-Huckel approximation for low surface potential at the channel wall, a complex variable approach is used to obtain an analytical solution for the flow. The complex counterparts of the flow rate and the current are linearly dependent on the pressure gradient and the external electric field. This property is used to show that Onsager's principle of reciprocity continues to be valid (involving the complex quantities) for the stated problem. During oscillating pressure-driven flow, the electroviscous effect for a given value of the normalized reciprocal electrical double-layer (EDL) thickness is observed to attain a maximum at a certain normalized frequency. In general, an increasing normalized frequency results in a reduction of EDL effects, leading to (i). a volumetric flow rate in the case of streaming potential approaching that predicted by the theory without EDL effects, and (ii). a reduction in the volumetric flow rate in the case of electroosmosis. PMID:12725819

  15. Enhanced transport of materials into enamel nanopores via electrokinetic flow.

    PubMed

    Gan, H Y; Sousa, F B; Carlo, H L; Maciel, P P; Macena, M S; Han, J

    2015-04-01

    The ability to infiltrate various molecules and resins into dental enamel is highly desirable in dentistry, yet transporting materials into dental enamel is limited by the nanometric scale of their pores. Materials that cannot be infiltrated into enamel by diffusion/capillarity are often considered molecules with sizes above a critical threshold, which are often considered to be larger than the pores of enamel. We challenge this notion by reporting the use of electrokinetic flow to transport solutions with molecules with sizes above a critical threshold-namely, an aqueous solution with a high refractive index (Thoulet's solution) and a curable fluid resin infiltrant (without acid etching)-deep into the normal enamel layer. Volume infiltration by Thoulet's solution is increased by 5- to 6-fold, and resin infiltration depths as large as 600 to 2,000 µm were achieved, in contrast to ~10 µm resulting from diffusion/capillarity. Incubation with demineralization solution for 192 h resulted in significant demineralization at noninfiltrated histologic points but not at resin infiltrated. These results open new avenues for the transport of materials in dental enamel.

  16. Enhanced transport of materials into enamel nanopores via electrokinetic flow.

    PubMed

    Gan, H Y; Sousa, F B; Carlo, H L; Maciel, P P; Macena, M S; Han, J

    2015-04-01

    The ability to infiltrate various molecules and resins into dental enamel is highly desirable in dentistry, yet transporting materials into dental enamel is limited by the nanometric scale of their pores. Materials that cannot be infiltrated into enamel by diffusion/capillarity are often considered molecules with sizes above a critical threshold, which are often considered to be larger than the pores of enamel. We challenge this notion by reporting the use of electrokinetic flow to transport solutions with molecules with sizes above a critical threshold-namely, an aqueous solution with a high refractive index (Thoulet's solution) and a curable fluid resin infiltrant (without acid etching)-deep into the normal enamel layer. Volume infiltration by Thoulet's solution is increased by 5- to 6-fold, and resin infiltration depths as large as 600 to 2,000 µm were achieved, in contrast to ~10 µm resulting from diffusion/capillarity. Incubation with demineralization solution for 192 h resulted in significant demineralization at noninfiltrated histologic points but not at resin infiltrated. These results open new avenues for the transport of materials in dental enamel. PMID:25691072

  17. AC electrokinetic manipulation of selenium nanoparticles for potential nanosensor applications

    SciTech Connect

    Mahmoodi, Seyed Reza; Bayati, Marzieh; Hosseinirad, Somayeh; Foroumadi, Alireza; Gilani, Kambiz; Rezayat, Seyed Mahdi

    2013-03-15

    Highlights: ► Se nanoparticles were synthesized using a reverse-microemulsion process. ► AC osmotic fluid flow repulses the particles from electrode edges. ► Dielectrophoretic force attracts the particles to electrode edges. ► Dielectrophoresis electrode showed non-ohmic behavior. ► The device can potentially be used as a nanosensor. - Abstract: We report the AC electrokinetic behavior of selenium (Se) nanoparticles for electrical characterization and possible application as micro/nano devices. selenium Se nanoparticles were successfully synthesized using a reverse-microemulsion process and investigated structurally using X-ray diffraction and transmission electron microscope. Interdigitated castellated ITO and non-castellated platinum electrodes were employed for manipulation of suspended materials in the fluid. Using ITO electrodes at low frequency limits resulted in deposition of Se particles on electrode surface. When Se particles exposed to platinum electrodes in the 10 Hz–1 kHz range and V {sub p−p}> 8, AC osmotic fluid flow repulses the particles from electrode edges. However, in 10 kHz–10 MHz range and V {sub p−p}> 5, dielectrophoretic force attracts the particles to electrode edges. As the Se particle concentration increased, the trapped Se particles were aligned along the electric field line and bridged the electrode gap. The device was characterized and can potentially be useful in making micro/nano electronic devices.

  18. Micellar electrokinetic chromatography of organic and peroxide-based explosives.

    PubMed

    Johns, Cameron; Hutchinson, Joseph P; Guijt, Rosanne M; Hilder, Emily F; Haddad, Paul R; Macka, Mirek; Nesterenko, Pavel N; Gaudry, Adam J; Dicinoski, Greg W; Breadmore, Michael C

    2015-05-30

    CE methods have been developed for the analysis of organic and peroxide-based explosives. These methods have been developed for deployment on portable, in-field instrumentation for rapid screening. Both classes of compounds are neutral and were separated using micellar electrokinetic chromatography (MEKC). The effects of sample composition, separation temperature, and background electrolyte composition were investigated. The optimised separation conditions (25 mM sodium tetraborate, 75 mM sodium dodecyl sulfate at 25°C, detection at 200 nm) were applied to the separation of 25 organic explosives in 17 min, with very high efficiency (typically greater than 300,000 plates m(-1)) and high sensitivity (LOD typically less than 0.5 mg L(-1); around 1-1.5 μM). A MEKC method was also developed for peroxide-based explosives (10 mM sodium tetraborate, 100 mM sodium dodecyl sulfate at 25°C, detection at 200 nm). UV detection provided LODs between 5.5 and 45.0 mg L(-1) (or 31.2-304 μM), which is comparable to results achieved using liquid chromatography. Importantly, no sample pre-treatment or post-column reaction was necessary and the peroxide-based explosives were not decomposed to hydrogen peroxide. Both MEKC methods have been applied to pre-blast analysis and for the detection of post-blast residues recovered from controlled, small scale detonations of organic and peroxide-based explosive devices. PMID:25998463

  19. Micellar electrokinetic capillary chromatography of benzodiazepines in human urine.

    PubMed

    Schafroth, M; Thormann, W; Allemann, D

    1994-01-01

    The determination of the major urinary compounds of eight common benzodiazepines, flunitrazepam, diazepam, midazolam, clonazepam, bromazepam, temazepam, oxazepam, and lorazepam, by micellar electrokinetic capillary chromatography (MECC) is shown to be a simple and attractive approach for confirmation testing of these drugs in human urine. After enzymatic hydrolysis and extraction using mixed-mode solid-phase cartridges and a two-step elution protocol, fractions were analyzed in a phosphate/borate buffer (pH 9.3) containing 75 mM sodium dodecyl sulfate and small amounts of isopropanol, methanol and/or acetonitrile using an instrument with on- column multi-wavelength detection. The presence of these compounds could unambiguously be confirmed in patient urines which tested positive for benzodiazepines using a commercial enzyme multiplied immunoassay screening technique (EMIT). The sensitivity of the MECC assay is demonstrated to be better than that of EMIT. MECC analysis of one patient urine which tested negatively employing EMIT revealed the presence of lorazepam, this demonstrating that false-negative results from the initial immunological screening process can be recognized using MECC. For one example, 7-aminoflunitrazepam, the MECC data are shown to agree well with those obtained by gas chromatography/mass spectrometry.

  20. The use of microemulsion electrokinetic chromatography in pharmaceutical analysis.

    PubMed

    Miola, M F; Snowden, M J; Altria, K D

    1998-12-01

    The use of a single set of microemulsion electrokinetic chromatography (MEEKC) separation conditions has been assessed for its applicability in the analysis of a range of pharmaceutical compounds. Particular emphasis was placed on neutral or very hydrophobic compounds, which can be difficult to analyse by conventional capillary electrophoresis. The microemulsion employed for the majority of separations consisted of 0.81% w/w octane, 6.61% w/w 1-butanol, 3.31% w/w sodium dodecyl sulphate and 89.27% w/w 10 mM sodium tetraborate buffer. Good separations of methyl, ethyl, butyl and propyl hydroxybenzoates, and a range of ionic and neutral water soluble and insoluble compounds was achieved using a single set of separation conditions. A number of novel applications of MEEKC were developed included the simultaneous determination of the active components and preservatives in liquid formulation and determination of drug related impurities. Improved performance was obtained through use of internal standards and preparation of the samples dissolved in the microemulsion solution. Validation aspects such as linearity, repeatability, accuracy, injection precision and sensitivity were successfully assessed. PMID:9919981

  1. Copper cation removal in an electrokinetic cell containing zeolite.

    PubMed

    Elsayed-Ali, Omar H; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E

    2011-01-30

    Zeolites are used in environmental remediation of soil or water to immobilize or remove toxic materials by cation exchange. An experiment was conducted to test the use a low electric field to direct the toxic cations towards the zeolite. An electrokinetic cell was constructed using carbon electrodes. Synthetic Linde Type A (LTA) zeolite was placed in the cell. Copper(II) chloride dissolved in water was used as a contaminant. The Cu(2+) concentration was measured for ten hours with and without an applied electric field. The removal of the Cu(2+) ions was accelerated by the applied field in the first two hours. For longer time, the electric field did not improve the removal rate of the Cu(2+) ions. The presence of zeolite and applied electric field complicates the chemistry near the cathode and causes precipitation of Cu(2+) ions as copper oxide on the surface of the zeolite. With increased electric field the zeolite farther away from the cathode had little cation exchange due to the higher drift velocity of the Cu(2+) ions. The results also show that, in the LTA Zeolite A pellets, the cation exchange of Cu is limited to a shell of several tens of micrometers. PMID:21109348

  2. Dispersion and absorption of longitudinal electro-kinetic wave in ion-implanted GaN semiconductor plasmas

    SciTech Connect

    Soni, Dilip; Sharma, Giriraj; Saxena, Ajay; Jadhav, Akhilesh

    2015-07-31

    An analytical study on propagation characteristics of longitudinal electro-kinetic (LEK) waves is presented. Based on multi-fluid model of plasma, we have derived a dispersion relation for LEK waves in colloid laden GaN semiconductor plasmas. It is assumed that ions are implanted to form colloids in the GaN sample. The colloids are continuously bombarded by the plasma particles and stick on them, but they acquire a net negative charge due to relatively higher mobility of electrons. It is found from the dispersion relation that the presence of charged colloids not only modifies the existing modes but also supports new novel modes of LEKWs. It is hoped that the study would enhance understanding on dispersion and absorption of LEKWs and help in singling out the appropriate configurations in which GaN crystal would be better suited for fabrication of microwave devices.

  3. On benchmark problems, challenges, and competitions in electrokinetics-A review.

    PubMed

    Hurák, Zdeněk; Foret, František

    2015-07-01

    In this critical review, we comment on the absence of widely shared benchmark problems and relevant challenges or even attractive competitions in the field of electrokinetics. We argue that in some other scientific domains that are, similarly as electrokinetics, strongly multidisciplinary, the existence of these tools is very beneficial because it stimulates the discussion about what constitutes the bottleneck of further progress, allows easier exploitation of results provided by other scientific and engineering disciplines, and, last but not least, makes the research domain attractive and visible to a broader public, including students. The goal of this review is to provoke some discussion that might perhaps lead to compensating for these shortcomings.

  4. Simultaneous removal of organic compounds and heavy metals from soils by electrokinetic remediation with a modified cyclodextrin.

    PubMed

    Maturi, Kranti; Reddy, Krishna R

    2006-05-01

    Thousands of sites are contaminated with both heavy metals and organic compounds and these sites pose a major threat to public health and the environment. Previous studies have shown that electrokinetic remediation has potential to remove heavy metals and organic compounds when they exist individually in low permeability soils. This paper presents the feasibility of using cyclodextrins in electrokinetic remediation for the simultaneous removal of heavy metals and polycyclic aromatic hydrocarbons (PAHs) from low permeability soils. Kaolin was selected as a model low permeability soil and it was spiked with phenanthrene as well as nickel at concentrations of 500 mg kg-1 each to simulate typical mixed field contamination. Bench-scale electrokinetic experiments were conducted using hydroxypropyl beta-cyclodextrin (HPCD) at low (1%) and high (10%) concentrations and using deionized water in control test. A periodic voltage gradient of 2VDC cm-1 (with 5 d on and 2 d off) was applied to all the tests, and 0.01 M NaOH was added during the experiments to maintain neutral pH conditions at anode. In all tests, nickel migrated as Ni2+ ions towards the cathode and most of it was precipitated as Ni(OH)2 within the soil close to the cathode due to high pH condition generated by electrolysis reaction. The solubility of phenanthrene in the flushing solution and the amount of electroosmotic flow controlled the migration and removal of phenanthrene in all the tests. Even though high flow was generated in tests using deionized water and 1% HPCD, migration and removal of phenanthrene was low due to low solubility of phenanthrene in these solutions. The test with 10% HPCD solution showed higher solubility of phenanthrene which caused it migrate towards the cathode, but further migration and removal was retarded due to reduced electric current and electroosmotic flow. Approximately one pore volume of flushing resulted in approximately 50% removal of phenanthrene from the soil near the

  5. [Analysis of nine narcotics in urine by microemulsion electrokinetic chromatography-field samplified sample injection].

    PubMed

    Zhang, Yu; Li, Qin; Lu, Minghua; Zhang, Lan; Chen, Guonan; Cai, Zongwei

    2011-08-01

    A simple, sensitive and reproducible method using microemulsion electrokinetic chromatography (MEEKC)-field amplified sample injection (FASI) was developed for the analysis of nine narcotics (morphine, codeine, naloxone, heroin, thebaine, cocaine, pethidine, fentanyl and methadone) in urine. In the MEEKC method, sodium dodecyl sulfate (SDS), 1-butanol and ethyl acetate were used as surfactant, co-surfactant and organic solvent, respectively. The effects of the acidity and concentration of borate buffer, SDS, 1-butanol and ethyl acetate contents were investigated. The optimum concentrations (by mass fraction) of microemulsion system were 0.6% SDS, 1.2% 1-butanol, 0.6% ethyl acetate and 97.6% 10 mmol/L Na2B4O7 buffer (pH 9.5). The applied voltage was 25 kV. FASI was coupled with the MEEKC method to increase the sensitivity. Under the optimum conditions, the nine narcotics were baseline separated within 15 min and the detection limits (S/N = 3) were in the range of 0.3 - 8.0 microg/L. The spiked recoveries in urine samples were between 79.4% and 119.9% with the intraday relative standard deviations (RSDs) less than 5.5%. The developed method has been successfully applied to the analysis of methadone in the samples from in vitro metabolism study.

  6. Specific ion effects on the electrokinetic properties of iron oxide nanoparticles: experiments and simulations.

    PubMed

    Vereda, Fernando; Martín-Molina, Alberto; Hidalgo-Alvarez, Roque; Quesada-Pérez, Manuel

    2015-07-14

    We report experimental and simulation studies on ion specificity in aqueous colloidal suspensions of positively charged, bare magnetite nanoparticles. Magnetite has the largest saturation magnetization among iron oxides and relatively low toxicity, which explain why it has been used in multiple biomedical applications. Bare magnetite is hydrophilic and the sign of the surface charge can be changed by adjusting the pH, its isoelectric point being in the vicinity of pH = 7. Electrophoretic mobility of our nanoparticles in the presence of increasing concentrations of different anions showed that anions regarded as kosmotropic are more efficient in decreasing, and even reversing, the mobility of the particles. If the anions were ordered according to the extent to which they reduced the particle mobility, a classical Hofmeister series was obtained with the exception of thiocyanate, whose position was altered. Monte Carlo simulations were used to predict the diffuse potential of magnetite in the presence of the same anions. The simulations took into account the ion volume, and the electrostatic and dispersion forces among the ions and between the ions and the solid surface. Even though no fitting parameters were introduced and all input data were estimated using Lifshitz theory of van der Waals forces or obtained from the literature, the predicted diffusion potentials of different anions followed the same order as the mobility curves. The results suggest that ionic polarizabilities and ion sizes are to a great extent responsible for the specific ion effects on the electrokinetic potential of iron oxide particles. PMID:26067087

  7. Investigation of the electrokinetic properties of paraffin suspension. 2. In cationic and anionic surfactant solutions.

    PubMed

    Chibowski, Emil; Wiacek, Agnieszka; Holysz, Lucyna; Terpilowski, Konrad

    2005-08-16

    Electrical phenomena at nonionogenic hydrophobic surfaces (solid or liquid) in water, electrolyte, and/or surfactant solutions still attract research. In part 1 of this paper we described the electrokinetic behavior of paraffin wax suspension in water and electrolyte solutions (NaCl or LaCl3). On the basis of the latest data of water structure near hydrophobic surfaces it was concluded that immobilized water dipoles at the interface can play an essential role in the zeta potential formation. In this paper were investigated the zeta potentials of paraffin wax in cationic surfactants cetyltrimethylammonium bromide, C16H33(CH3)3NBr, and octadecyltrimethylammonium chloride, C18H37(CH3)3NCl, and anionic surfactant sodium dodecyl sulfate, C12H25SO4Na. Also changes in wettability of the paraffin surface due to the surfactant's adsorption were studied via wetting contact angle measurements and calculation of the surface free energy. It was concluded that at a low surfactant concentration (10(-6) M) the water dipole structure still contributes to the zeta potential, but at a higher one the zeta potential is determined by the surfactant molecules' adsorption. A special role of OH- ions is also clearly seen. Moreover, a functional relationship was found between the surface free energy of the surfactant-covered paraffin surface and the zeta potential.

  8. Structure selective complexation of cyclodextrins with five polyphenols investigated by capillary electrokinetic chromatography.

    PubMed

    Zhang, Qing-Feng; Cheung, Hon-Yeung; Shangguan, Xinchen; Zheng, Guodong

    2012-12-01

    The complexation of five polyphenols, namely trans-resveratrol, astilbin, taxifolin, ferulic acid, and syringic acid (guest molecules) with α-, β-, and γ-cyclodextrin (host molecules), was investigated by capillary electrokinetic chromatography. The binding constants were calculated based on the effective electrophoretic mobility change of guests with the addition of cyclodextrins into the background electrolyte. Because of cavity size, cyclodextrins showed structure-selective complexation property to different guest. The stability of the trans-resveratrol complexes was in the order of β- > α- > γ-cyclodextrin. The cavity size of α-cyclodextrin was too small for astilbin and taxifolin molecules, and thus they could not form complexes. The molecular size of syringic acid was too big for all cyclodextrins cavity, and no cyclodextrin could form complexes with it. Temperature studies showed that the binding constants decreased with the rise of temperature. Enthalpy and entropy values were calculated and the negative values of these parameters indicated that the complexation process was enthalpy-controlled. Van der Waals force and release of high-enthalpy water molecules from the cyclodextrins cavity played important roles in the process. PMID:23184372

  9. Enhanced biodegradation of pentachlorophenol in unsaturated soil using reversed field electrokinetics.

    PubMed

    Harbottle, Michael J; Lear, Gavin; Sills, Gilliane C; Thompson, Ian P

    2009-04-01

    This study investigated the use of electrokinetics in unsaturated soil to promote biodegradation of pentachlorophenol through increased contact between bacteria and contaminant. Soil microcosms, contaminated with approximately 100 mg kg(-1) pentachlorophenol (containing [(14)C]-PCP as a tracer), and inoculated with a specific pentachlorophenol-degrading bacterium (Sphingobium sp. UG30-1 x 10(8) cfu g(-1)) were subjected to constant and regularly reversed electric currents (10 mA). The former caused large pH and moisture content changes due to water electrolysis and electroosmotic effects, with subsequent negative impacts on biodegradation parameters including enzyme activity and contaminant mineralisation (as measured by (14)CO(2) evolution rate). The reversed field caused little change in pH and moisture content and led to more rapid contaminant mineralisation, lower soil contaminant concentration in the majority of the microcosms and increased soil enzyme activity (with the exception of soil immediately adjacent to the anode). The presence of an electric field, if suitably applied, may therefore enhance contaminant biodegradation in unsaturated soil.

  10. Electrokinetic remediation of wood preservative contaminated soil containing copper, chromium, and arsenic.

    PubMed

    Buchireddy, Prashanth R; Bricka, R Mark; Gent, David B

    2009-02-15

    As a result of wood treatment, and the recent banning of the copper, chromium, and arsenic (CCA) treated wood for residential use many CCA treatment facilities have been abandoned or being closed. Soil contamination resulting from CCA is common at these sites. In this study, the feasibility of electrokinetic technique to remove CCA from contaminated soil was investigated. To better understand the ionic mobility within the soil and to detect the generation and advancement of acid front, sampling ports were provided along the longitudinal axis of a test cell. To determine the effect of varying current, three tests were performed at different current densities of 5.9, 2.9, and 1.5mA/cm(2) for a period of 15 days. The initial concentrations of copper, chromium, and arsenic in the soil were 4800, 3100, and 5200mg/kg, respectively. Dilute nitric acid was used as an amendment to neutralize the hydroxyl ions produced at the cathode. Experiments resulted in removal efficiencies as high as 65% for copper, 72% for chromium, and 77% for arsenic. The results also indicated that the advancement of acid front favored desorption of metals from the soil and the metals were mobilized either as free cations or metal complexes. Chromium that was in its +6 valence state was transported as anion prior to its reduction. However, once the chromium was reduced to chromium(III) its transport direction reversed with transport being favored towards the cathode.

  11. Analysis of volatile components in Curcuma rhizome by microemulsion electrokinetic chromatography.

    PubMed

    Yang, Feng-Qing; Yang, Jing; Zhang, Xue-Mei; Xu, Pan; Xia, Zhi-Ning

    2013-02-01

    Volatile chemicals are a group of very important compounds in natural products. Curcuma rhizome, which contains many bioactive volatile compounds, is a traditional Chinese medicine that has long been used for the treatment of several diseases. In the present study, a microemulsion electrokinetic chromatography (MEEKC) method was developed for the analysis of four volatile components in Curcuma rhizome, including germacrone, furanodiene, curcumenol and curdione. Experimental parameters, including the pH, type and concentrations of background electrolyte, and microemulsion compositions (type and concentrations of surfactant, co-surfactant and oil phase) were intensively investigated. Finally, the primary compounds in the methanol extract of Curcuma rhizome were separated within 30 min using a running buffer composed of 2.31% w/v (80 mmol/L) sodium dodecyl sulfate (SDS), 0.91% w/v (80 mmol/L) 1-octane, 6.95% w/v (937.5 mmol/L) 1-butanol and 1.88% w/v (312.5 mmol/L) propanol in a 5-mM borate buffer (pH 8.1). The contents of the four investigated compounds were determined in the rhizome from C. phaeocaulis. The results showed that the developed MEEKC method provided an alternative tool for the analysis of volatile components, especially those of heat-sensitive compounds from natural products.

  12. Characterization of molds isolated from smoked paprika by PCR-RFLP and micellar electrokinetic capillary electrophoresis.

    PubMed

    Ruiz-Moyano, Santiago; Benito, María J; Martín, Alberto; Aranda, Emilio; Hernández, Alejandro; Córdoba, María G

    2009-12-01

    Molds are common contaminants of paprika meat products. The drying and storage stages of paprika processing are critical because they can provide molds with the conditions particularly appropriate for their growth and proliferation. Thus, an efficient and accurate characterization of the toxigenic molds of paprika is necessary. An RFLP analysis of the rRNA genes was performed by using a TaqI restriction enzyme. In addition, a micellar electrokinetic capillary chromatography (MECC) method was tested to analyze secondary metabolites produced by mold strains commonly found in paprika. This study was confirmed with a 5.8S-ITS region sequence analysis. A total of 31 isolates were identified by RFLP and MECC analysis. These showed stable RFLP profiles that were clearly different for the different genera and species, and were grouped into clusters together with the profiles of the 16 reference strains. MECC analysis provided additional characteristic peak patterns for the characterization of the mold species present. The characterized isolates were species of the genera Fusarium spp., Aspergillus spp., Penicillium spp., Cladosporium spp., Mucor spp. and Phlebia spp. The identifications were confirmed by the 5.8S-ITS region sequence analysis and by a BLAST search of the GenBank database. RFLP patterns with TaqI restriction enzyme and MECC profiles, either singly or combined, could be of great interest to distinguish molds in paprika.

  13. Transient electrokinetic transport in micro/nanofluidic systems with sudden expansion and contraction cross sections

    NASA Astrophysics Data System (ADS)

    Chein, Reiyu; Liao, Yuchung

    2013-03-01

    This study numerically investigates electrokinetic transport in a micro/nanofluidic system by solving the transient Poisson, Nernst-Planck, and Navier-Stokes equations simultaneously. The considered system is a nanochannel connected to two micro channels at its ends. Under various applied electric potential biases, the concentration polarization effect on the fluid flow, induced pressure, and electric current is examined. By comparing with the Donnan equilibrium condition and electroosmotic flow in the microscale dimension, electric body force due to non-zero charge density is the mechanism for producing vortex flow and inducing a positive pressure gradient on the anodic side of the system. The diffusive boundary layer thickness is reduced due to stirring by the generated vortex flow, resulting in over-limiting current when the applied electric potential bias is high. The steady-state current voltage curve indicates that in the Ohmic regime, higher current can be obtained when the surface charge density is large due to higher fluid velocity. In the limiting and over-limiting current regimes, higher electric current can be obtained when the nanochannel is larger with smaller surface density because more ions are available for carrying the current. The nanochannel size effect on the limiting and over-limiting current magnitudes is insignificant when the surface charge density is large.

  14. Simultaneous determination of eleven preservatives in cosmetics by micellar electrokinetic chromatography.

    PubMed

    Wang, Ping; Ding, Xiaojing; Li, Yun; Yang, Yuanyuan

    2012-01-01

    A new method for the simultaneous quantitation of 11 preservatives-imidazolidinyl urea, benzyl alcohol, dehydroacetic acid, sorbic acid, phenoxyethanol, benzoic acid, salicylic acid, and four parabens (methyl, ethyl, propyl, and butyl)-in cosmetics by micellar electrokinetic capillary chromatography was established and validated. The separation was performed using an uncoated fused-silica capillary (50 pm id x 60.2 cm, effective length 50 cm) with a running buffer consisting of 15 mmol/L sodium tetraborate, 60 mmol/L boric acid, and 100 mmol/L sodium dodecyl sulfate. A 1:10 dilution of the running buffer was used as the sample buffer to extract the cosmetic samples. The key factors, such as the concentration and pH of the running and sample buffers, which influence quantitative analysis of the above 11 preservatives in cosmetic samples, were investigated in detail. The linear ranges of the calibration curves for imidazolidinyl urea and the other 10 preservatives were 50-1000 and 10-200 mg/L, respectively. The correlation coefficients of the standard curves were all higher than 0.999. The recoveries at the concentrations studied ranged from 93.0 to 102.7%. RSDs were all less than 5%. The new method with simple sample pretreatment met the needs for routine analysis of the 11 preservatives in cosmetics.

  15. Separation and determination of nimesulide related substances for quality control purposes by micellar electrokinetic chromatography.

    PubMed

    Zacharis, Constantinos K; Tzanavaras, Paraskevas D; Notou, Maria; Zotou, Anastasia; Themelis, Demetrius G

    2009-02-20

    A micellar electrokinetic chromatography (MEKC) method has been developed and validated for the determination of nimesulide related compounds in pharmaceutical formulations. Electrophoretic separation of six European Pharmacopoeia (EP) impurities (A-F) was performed using a fused silica capillary (L(eff.)=50 cm, L(tot.)=57 cm, 50 microm i.d.) with a background electrolyte (BGE) containing 25 mM borate buffer (pH 9.5), 30 mM sodium dodecyl sulphate and phi=3% (v/v) acetonitrile. The influence of several factors (surfactant and buffer concentration, pH, organic modifier, applied voltage, capillary temperature and injection time) was studied. The method was suitably validated with respect to linearity, limit of detection and quantification, accuracy, precision and selectivity. The calibration curves obtained for the six compounds were linear over the range 5-12 microgml(-1) (0.05-0.12%). The relative standard deviations (s(r)) of intra- and inter-day experiments were less than 5.0%. The detection limits ranged between 0.7 and 1.6 microgml(-1) depending on the impurity. The proposed method was applied successfully to the quantification of nimesulide impurities in its pharmaceutical formulation.

  16. Self-consistent description of electrokinetic phenomena in particle-based simulations

    PubMed Central

    de Pablo, Juan J.

    2015-01-01

    A new computational method is presented for study suspensions of charged particles undergoing fluctuating hydrodynamic and electrostatic interactions. The proposed model is appropriate for polymers, proteins, and porous particles embedded in a continuum electrolyte. A self-consistent Langevin description of the particles is adopted in which hydrodynamic and electrostatic interactions are included through a Green’s function formalism. An Ewald-like split is adopted in order to satisfy arbitrary boundary conditions for the Stokeslet and Poisson Green functions, thereby providing a formalism that is applicable to any geometry and that can be extended to deformable objects. The convection-diffusion equation for the continuum ions is solved simultaneously considering Nernst-Planck diffusion. The method can be applied to systems at equilibrium and far from equilibrium. Its applicability is demonstrated in the context of electrokinetic motion, where it is shown that the ionic clouds associated with individual particles can be severely altered by the flow and concentration, leading to intriguing cooperative effects. PMID:26156466

  17. Specific ion effects on the electrokinetic properties of iron oxide nanoparticles: experiments and simulations.

    PubMed

    Vereda, Fernando; Martín-Molina, Alberto; Hidalgo-Alvarez, Roque; Quesada-Pérez, Manuel

    2015-07-14

    We report experimental and simulation studies on ion specificity in aqueous colloidal suspensions of positively charged, bare magnetite nanoparticles. Magnetite has the largest saturation magnetization among iron oxides and relatively low toxicity, which explain why it has been used in multiple biomedical applications. Bare magnetite is hydrophilic and the sign of the surface charge can be changed by adjusting the pH, its isoelectric point being in the vicinity of pH = 7. Electrophoretic mobility of our nanoparticles in the presence of increasing concentrations of different anions showed that anions regarded as kosmotropic are more efficient in decreasing, and even reversing, the mobility of the particles. If the anions were ordered according to the extent to which they reduced the particle mobility, a classical Hofmeister series was obtained with the exception of thiocyanate, whose position was altered. Monte Carlo simulations were used to predict the diffuse potential of magnetite in the presence of the same anions. The simulations took into account the ion volume, and the electrostatic and dispersion forces among the ions and between the ions and the solid surface. Even though no fitting parameters were introduced and all input data were estimated using Lifshitz theory of van der Waals forces or obtained from the literature, the predicted diffusion potentials of different anions followed the same order as the mobility curves. The results suggest that ionic polarizabilities and ion sizes are to a great extent responsible for the specific ion effects on the electrokinetic potential of iron oxide particles.

  18. Novel Electrokinetic Microfluidic Detector for Evaluating Effectiveness of Microalgae Disinfection in Ship Ballast Water

    PubMed Central

    Maw, Myint Myint; Wang, Junsheng; Li, Fabo; Jiang, Jinhu; Song, Younan; Pan, Xinxiang

    2015-01-01

    Ship ballast water treatment methods face many technical challenges. The effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples, which involves time-consuming, laborious, and complex operations. This paper reports the development of a novel, simple and fast platform of methodology in evaluating the efficiency and the best parameters for ballast water treatment systems, particularly in chemical disinfection. In this study, a microfluidic chip with six sample wells and a waste well was designed, where sample transportation was controlled by electrokinetic flow. The performance of this microfluidic platform was evaluated by detecting the disinfection of Dunaliella salina (D. salina) algae in ballast water treated by sodium hypochlorite (NaClO) solution. Light-induced chlorophyll fluorescence (LICF) intensity was used to determine the viability of microalgae cells in the system, which can be operated automatically with the dimension of the detector as small as 50 mm × 24 mm × 5 mm. The 40 µL volume of sample solution was used for each treatment condition test and the validity of detection can be accomplished within about five min. The results show that the viability of microalgae cells under different treatment conditions can be determined accurately and further optimal treatment conditions including concentrations of NaClO and treatment time can also be obtained. These results can provide accurate evaluation and optimal parameters for ballast water treatment methods. PMID:26516836

  19. Preparation and evaluation of bonded linear polymethacrylate stationary phases for open tubular capillary electrokinetic chromatography

    SciTech Connect

    Tan, Z.J.; Remcho, V.T.

    1997-02-15

    A new procedure for the preparation of thick polymethacrylate films bonded in 25 {mu}m i.d. fused-silica capillaries is developed. The etched silica surface is first modified with an unsaturated organosilane, which is later incorporated into the polymer film. The capillary is then filled with a monomer solution, and polymerization is initiated by incubation at elevated temperature. This thermoinitiation method enables the use of ordinary polyimide-jacketed capillaries in preparing the columns. The effect of monomer concentration on the resulting polymer film was studied by open tubular capillary electrokinetic chromatography using p-hydroxybenzoates (parabens) as test solutes. Good separations were achieved using short capillaries. Run-to-run retention time reproducibility was excellent, with RSDs of 2% (n = 50) being representative. For the linear polymer films produced, retention of analytes increased as the monomer concentration increased to a certain value, at which point the capacity factors level off with further increases in monomer concentration. The electroosmotic flow velocity decreases with increasing monomer concentration. The efficiency for an unretained test probe (acetone) reaches 270 000 plates/m. 13 refs., 10 figs., 1 tab.

  20. Analysis of reducing carbohydrates by reductive tryptamine derivatization prior to micellar electrokinetic capillary chromatography.

    PubMed

    Andersen, Keld E; Bjergegaard, Charlotte; Sørensen, Hilmer

    2003-12-01

    A micellar electrokinetic capillary chromatography method for determination of low molecular weight carbohydrates (dp 1-2) with an unbound carbonyl group as in aldoses or other reducing carbohydrates has been developed. Reductive amination of aldoses on the carbonyl group using tryptamine introduced a chromophor system to the carbohydrates enabling their sensitive UV detection at 220 nm and identification based on the indole group using diode array detection. Twelve carbohydrates including pentoses (d-ribose, l-arabinose, and d-xylose), hexoses (d-glucose, d-mannose, and d-galactose), deoxy sugars (l-rhamnose and l-fucose), uronic acids (d-glucuronic acid and d-galacturonic acid), and disaccharides (cellobiose and melibiose) are included in the study, using d-thyminose (2-deoxy-d-ribose) as the internal standard. Detection of all 12 carbohydrates is performed within 30 min. Linearity with correlation coefficients from 0.9864 to 0.9992 was found in the concentration range of 25-2500 micromol/L for all carbohydrates; the relative standard deviation on the migration times was between 0.27 and 0.80 min, and limits of quantification and limits of determination were in the picomole range.

  1. Recovery of Drug Delivery Nanoparticles from Human Plasma Using an Electrokinetic Platform Technology.

    PubMed

    Ibsen, Stuart; Sonnenberg, Avery; Schutt, Carolyn; Mukthavaram, Rajesh; Yeh, Yasan; Ortac, Inanc; Manouchehri, Sareh; Kesari, Santosh; Esener, Sadik; Heller, Michael J

    2015-10-01

    The effect of complex biological fluids on the surface and structure of nanoparticles is a rapidly expanding field of study. One of the challenges holding back this research is the difficulty of recovering therapeutic nanoparticles from biological samples due to their small size, low density, and stealth surface coatings. Here, the first demonstration of the recovery and analysis of drug delivery nanoparticles from undiluted human plasma samples through the use of a new electrokinetic platform technology is presented. The particles are recovered from plasma through a dielectrophoresis separation force that is created by innate differences in the dielectric properties between the unaltered nanoparticles and the surrounding plasma. It is shown that this can be applied to a wide range of drug delivery nanoparticles of different morphologies and materials, including low-density nanoliposomes. These recovered particles can then be analyzed using different methods including scanning electron microscopy to monitor surface and structural changes that result from plasma exposure. This new recovery technique can be broadly applied to the recovery of nanoparticles from high conductance fluids in a wide range of applications.

  2. Recovery of Drug Delivery Nanoparticles from Human Plasma Using an Electrokinetic Platform Technology.

    PubMed

    Ibsen, Stuart; Sonnenberg, Avery; Schutt, Carolyn; Mukthavaram, Rajesh; Yeh, Yasan; Ortac, Inanc; Manouchehri, Sareh; Kesari, Santosh; Esener, Sadik; Heller, Michael J

    2015-10-01

    The effect of complex biological fluids on the surface and structure of nanoparticles is a rapidly expanding field of study. One of the challenges holding back this research is the difficulty of recovering therapeutic nanoparticles from biological samples due to their small size, low density, and stealth surface coatings. Here, the first demonstration of the recovery and analysis of drug delivery nanoparticles from undiluted human plasma samples through the use of a new electrokinetic platform technology is presented. The particles are recovered from plasma through a dielectrophoresis separation force that is created by innate differences in the dielectric properties between the unaltered nanoparticles and the surrounding plasma. It is shown that this can be applied to a wide range of drug delivery nanoparticles of different morphologies and materials, including low-density nanoliposomes. These recovered particles can then be analyzed using different methods including scanning electron microscopy to monitor surface and structural changes that result from plasma exposure. This new recovery technique can be broadly applied to the recovery of nanoparticles from high conductance fluids in a wide range of applications. PMID:26274918

  3. Novel Electrokinetic Microfluidic Detector for Evaluating Effectiveness of Microalgae Disinfection in Ship Ballast Water.

    PubMed

    Maw, Myint Myint; Wang, Junsheng; Li, Fabo; Jiang, Jinhu; Song, Younan; Pan, Xinxiang

    2015-10-26

    Ship ballast water treatment methods face many technical challenges. The effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples, which involves time-consuming, laborious, and complex operations. This paper reports the development of a novel, simple and fast platform of methodology in evaluating the efficiency and the best parameters for ballast water treatment systems, particularly in chemical disinfection. In this study, a microfluidic chip with six sample wells and a waste well was designed, where sample transportation was controlled by electrokinetic flow. The performance of this microfluidic platform was evaluated by detecting the disinfection of Dunaliella salina (D. salina) algae in ballast water treated by sodium hypochlorite (NaClO) solution. Light-induced chlorophyll fluorescence (LICF) intensity was used to determine the viability of microalgae cells in the system, which can be operated automatically with the dimension of the detector as small as 50 mm × 24 mm × 5 mm. The 40 µL volume of sample solution was used for each treatment condition test and the validity of detection can be accomplished within about five min. The results show that the viability of microalgae cells under different treatment conditions can be determined accurately and further optimal treatment conditions including concentrations of NaClO and treatment time can also be obtained. These results can provide accurate evaluation and optimal parameters for ballast water treatment methods.

  4. Thrombin Production and Human Neutrophil Elastase Sequestration by Modified Cellulosic Dressings and Their Electrokinetic Analysis

    PubMed Central

    Edwards, Judson Vincent; Prevost, Nicolette

    2011-01-01

    Wound healing is a complex series of biochemical and cellular events. Optimally, functional material design addresses the overlapping acute and inflammatory stages of wound healing based on molecular, cellular, and bio-compatibility issues. In this paper the issues addressed are uncontrolled hemostasis and inflammation which can interfere with the orderly flow of wound healing. In this regard, we review the serine proteases thrombin and elastase relative to dressing functionality that improves wound healing and examine the effects of charge in cotton/cellulosic dressing design on thrombin production and elastase sequestration (uptake by the wound dressing). Thrombin is central to the initiation and propagation of coagulation, and elastase is released from neutrophils that can function detrimentally in a stalled inflammatory phase characteristic of chronic wounds. Electrokinetic fiber surface properties of the biomaterials of this study were determined to correlate material charge and polarity with function relative to thrombin production and elastase sequestration. Human neutrophil elastase sequestration was assessed with an assay representative of chronic wound concentration with cotton gauze cross-linked with three types of polycarboxylic acids and one phosphorylation finish; thrombin production, which was assessed in a plasma-based assay via a fluorogenic peptide substrate, was determined for cotton, cotton-grafted chitosan, chitosan, rayon/polyester, and two kaolin-treated materials including a commercial hemorrhage control dressing (QuickClot Combat Gauze). A correlation in thrombin production to zeta potential was found. Two polycarboxylic acid cross linked and a phosphorylated cotton dressing gave high elastase sequestration. PMID:24956451

  5. Thrombin production and human neutrophil elastase sequestration by modified cellulosic dressings and their electrokinetic analysis.

    PubMed

    Edwards, Judson Vincent; Prevost, Nicolette

    2011-12-15

    Wound healing is a complex series of biochemical and cellular events. Optimally, functional material design addresses the overlapping acute and inflammatory stages of wound healing based on molecular, cellular, and bio-compatibility issues. In this paper the issues addressed are uncontrolled hemostasis and inflammation which can interfere with the orderly flow of wound healing. In this regard, we review the serine proteases thrombin and elastase relative to dressing functionality that improves wound healing and examine the effects of charge in cotton/cellulosic dressing design on thrombin production and elastase sequestration (uptake by the wound dressing). Thrombin is central to the initiation and propagation of coagulation, and elastase is released from neutrophils that can function detrimentally in a stalled inflammatory phase characteristic of chronic wounds. Electrokinetic fiber surface properties of the biomaterials of this study were determined to correlate material charge and polarity with function relative to thrombin production and elastase sequestration. Human neutrophil elastase sequestration was assessed with an assay representative of chronic wound concentration with cotton gauze cross-linked with three types of polycarboxylic acids and one phosphorylation finish; thrombin production, which was assessed in a plasma-based assay via a fluorogenic peptide substrate, was determined for cotton, cotton-grafted chitosan, chitosan, rayon/polyester, and two kaolin-treated materials including a commercial hemorrhage control dressing (QuickClot Combat Gauze). A correlation in thrombin production to zeta potential was found. Two polycarboxylic acid cross linked and a phosphorylated cotton dressing gave high elastase sequestration.

  6. Simultaneous determination of multiclass preservatives including isothiazolinones and benzophenone-type UV filters in household and personal care products by micellar electrokinetic chromatography.

    PubMed

    Lopez-Gazpio, Josu; Garcia-Arrona, Rosa; Millán, Esmeralda

    2015-04-01

    In this work, a simple and reliable micellar electrokinetic chromatography method for the separation and quantification of 14 preservatives, including isothiazolinones, and two benzophenone-type UV filters in household, cosmetic and personal care products was developed. The selected priority compounds are widely used as ingredients in many personal care products, and are included in the European Regulation concerning cosmetic products. The electrophoretic separation parameters were optimized by means of a modified chromatographic response function in combination with an experimental design, namely a central composite design. After optimization of experimental conditions, the BGE selected for the separation of the targets consisted of 60 mM SDS, 18 mM sodium tetraborate, pH 9.4 and 10% v/v methanol. The MEKC method was checked in terms of linearity, LODs and quantification, repeatability, intermediate precision, and accuracy, providing appropriate values (i.e. R(2) ≥ 0.992, repeatability RSD values ˂9%, and accuracy 90-115%). Applicability of the validated method was successfully assessed by quantifying preservatives and UV filters in commercial consumer products.

  7. Gas-Chromatographic Determination Of Water In Freon PCA

    NASA Technical Reports Server (NTRS)

    Melton, Donald M.

    1994-01-01

    Gas-chromatographic apparatus measures small concentrations of water in specimens of Freon PCA. Testing by use of apparatus faster and provides greater protection against accidental contamination of specimens by water in testing environment. Automated for unattended operation. Also used to measure water contents of materials, other than Freon PCA. Innovation extended to development of purgeable sampling accessory for gas chromatographs.

  8. Detection system for a gas chromatograph

    DOEpatents

    Hayes, John M.; Small, Gerald J.

    1984-01-01

    A method and apparatus are described for the quantitative analysis of vaporizable compounds, and in particular of polycyclic aromatic hydrocarbons which may be induced to fluoresce. The sample to be analyzed is injected into a gas chromatography column and is eluted through a narrow orifice into a vacuum chamber. The free expansion of the eluted sample into the vacuum chamber creates a supersonic molecular beam in which the sample molecules are cooled to the extent that the excited vibrational and rotational levels are substantially depopulated. The cooled molecules, when induced to fluoresce by laser excitation, give greatly simplified spectra suitable for analytical purposes. The laser induced fluorimetry provides great selectivity, and the gas chromatograph provides quantitative transfer of the sample to the molecular beam.

  9. Fast gas chromatographic separation of biodiesel.

    SciTech Connect

    Pauls, R. E.

    2011-05-01

    A high-speed gas chromatographic method has been developed to determine the FAME distribution of B100 biodiesel. The capillary column used in this work has dimensions of 20 m x 0.100 mm and is coated with a polyethylene glycol film. Analysis times are typically on the order of 4-5 min depending upon the composition of the B100. The application of this method to a variety of vegetable and animal derived B100 is demonstrated. Quantitative results obtained with this method were in close agreement with those obtained by a more conventional approach on a 100 m column. The method, coupled with solid-phase extraction, was also found suitable to determine the B100 content of biodiesel-diesel blends.

  10. Chromatographic and electrophoretic approaches in ink analysis.

    PubMed

    Zlotnick, J A; Smith, F P

    1999-10-15

    Inks are manufactured from a wide variety of substances that exhibit very different chemical behaviors. Inks designed for use in different writing instruments or printing methods have quite dissimilar components. Since the 1950s chromatographic and electrophoretic methods have played important roles in the analysis of inks, where compositional information may have bearing on the investigation of counterfeiting, fraud, forgery, and other crimes. Techniques such as paper chromatography and electrophoresis, thin-layer chromatography, high-performance liquid chromatography, gas chromatography, gel electrophoresis, and the relatively new technique of capillary electrophoresis have all been explored as possible avenues for the separation of components of inks. This paper reviews the components of different types of inks and applications of the above separation methods are reviewed. PMID:10572985

  11. Interface for liquid chromatograph-mass spectrometer

    DOEpatents

    Andresen, B.D.; Fought, E.R.

    1989-09-19

    A moving belt interface is described for real-time, high-performance liquid chromatograph (HPLC)/mass spectrometer (MS) analysis which strips away the HPLC solvent as it emerges from the end of the HPLC column and leaves a residue suitable for mass-spectral analysis. The interface includes a portable, stand-alone apparatus having a plural stage vacuum station, a continuous ribbon or belt, a drive train magnetically coupled to an external drive motor, a calibrated HPLC delivery system, a heated probe tip and means located adjacent the probe tip for direct ionization of the residue on the belt. The interface is also capable of being readily adapted to fit any mass spectrometer. 8 figs.

  12. Interface for liquid chromatograph-mass spectrometer

    DOEpatents

    Andresen, Brian D.; Fought, Eric R.

    1989-01-01

    A moving belt interface for real-time, high-performance liquid chromatograph (HPLC)/mass spectrometer (MS) analysis which strips away the HPLC solvent as it emerges from the end of the HPLC column and leaves a residue suitable for mass-spectral analysis. The interface includes a portable, stand-alone apparatus having a plural stage vacuum station, a continuous ribbon or belt, a drive train magnetically coupled to an external drive motor, a calibrated HPLC delivery system, a heated probe tip and means located adjacent the probe tip for direct ionization of the residue on the belt. The interface is also capable of being readily adapted to fit any mass spectrometer.

  13. Gas Chromatographic Detectors for Exobiology Flight Experiments

    NASA Technical Reports Server (NTRS)

    Kojiro, Daniel R.; Humphry, Donald E.; Takeuchi, Nori; Chang, Sherwood (Technical Monitor)

    1997-01-01

    Exobiology flight experiments require highly sensitive instrumentation for in situ chemical analysis of the volatile chemical species that occur in the atmospheres and surfaces of various bodies within the solar system. The complex mixtures encountered place a heavy burden on the analytical instrumentation to detect and identify all species present. Future missions to Mars', comets, or planetary moons such as Europa, will perform experiments with complex analyses. In addition, instrumentation for such missions must perform under severely restricted conditions with limited resources. To meet these analytical requirements, improved methods and highly sensitive yet smaller instruments must continually be developed with increasingly greater capabilities. We describe here efforts to achieve this objective, for past and future missions, through the development of new or the improvement of existing sensitive, miniaturized gas chromatographic detectors.

  14. Chromatographic determination of amino acids in foods.

    PubMed

    Peace, Robert W; Gilani, G Sarwar

    2005-01-01

    Amino acids in foods exist in a free form or bound in peptides, proteins, or nonpeptide bonded polymers. Naturally occurring L-amino acids are required for protein synthesis and are precursors for essential molecules, such as co-enzymes and nucleic acids. Nonprotein amino acids may also occur in animal tissues as metabolic intermediates or have other important functions. The development of bacterially derived food proteins, genetically modified foods, and new methods of food processing; the production of amino acids for food fortification; and the introduction of new plant food sources have meant that protein amino acids and amino acid enantiomers in foods can have both nutritional and safety implications for humans. There is, therefore, a need for the rapid and accurate determination of amino acids in foods. Determination of the total amino acid content of foods requires protein hydrolysis by various means that must take into account variations in stability of individual amino acids and resistance of different peptide bonds to the hydrolysis procedures. Modern methods for separation and quantitation of free amino acids either before or after protein hydrolysis include ion exchange chromatography, high performance liquid chromatography (LC), gas chromatography, and capillary electrophoresis. Chemical derivatization of amino acids may be required to change them into forms amenable to separation by the various chromatographic methods or to create derivatives with properties, such as fluorescence, that improve their detection. Official methods for hydrolysis and analysis of amino acids in foods for nutritional purposes have been established. LC is currently the most widely used analytical technique, although there is a need for collaborative testing of methods available. Newer developments in chromatographic methodology and detector technology have reduced sample and reagent requirements and improved identification, resolution, and sensitivity of amino acid analyses

  15. An integrated method incorporating sulfur-oxidizing bacteria and electrokinetics to enhance removal of copper from contaminated soil

    SciTech Connect

    Maini, G.; Sharman, A.K.; Sunderland, G.; Knowles, C.J.; Jackman, S.A.

    2000-03-15

    The combination of bioleaching and electrokinetics for the remediation of metal contaminated land has been investigated. In bioleaching, bacteria convert reduced sulfur compounds to sulfuric acid, acidifying soil and mobilizing metal ions. In electrokinetics, DC current acidifies soil, and mobilized metals are transported to the cathode by electromigration. When bioleaching was applied to silt soil artificially contaminated with seven metals and amended with sulfur, bacterial activity was partially inhibited and limited acidification occurred. Electrokinetic treatment of silt soil contaminated solely with 1000 mg/kg copper nitrate showed 89% removal of copper from the soil within 15 days. To combine bioleaching and electrokinetics sequentially, preliminary partial acidification was performed by amending copper-contaminated soil with sulfur (to 5% w/w) and incubating at constant moisture (30% w/w) and temperature (20 C) for 90 days. Indigenous sulfur oxidizing bacteria partially acidified the soil from pH 8.1 to 5.4. This soil was then treated by electrokinetics yielding 86% copper removal in 16 days. In the combined process, electrokinetics stimulated sulfur oxidation, by removing inhibitory factors, yielding a 5.1-fold increase in soil sulfate concentration. Preacidification by sulfur-oxidizing bacteria increased the cost-effectiveness of the electrokinetic treatment by reducing the power requirement by 66%.

  16. Electrokinetic Evaluation of Individual Exosomes by On-Chip Microcapillary Electrophoresis with Laser Dark-Field Microscopy

    NASA Astrophysics Data System (ADS)

    Kato, Kei; Kobayashi, Masashi; Hanamura, Nami; Akagi, Takanori; Kosaka, Nobuyoshi; Ochiya, Takahiro; Ichiki, Takanori

    2013-06-01

    Cell-secreted nanovesicles called exosomes are expected as a promising candidate biomarker of various diseases. Toward the future application of exosomes as a disease biomarker for low-invasive diagnostics, challenges remain in the development of sensitive and precise analysis methods for exosomes. In this study, we performed the electrokinetic evaluation of individual exosomes by the combined use of on-chip microcapillary electrophoresis and laser dark-field microscopy. We extracted exosomes from six types of human cell cultured in a serum-free medium by differential ultracentrifugation and their zeta potential (electrophoretic mobility) were evaluated. We demonstrated that the proposed electrophoresis apparatus is particularly suitable for the tracking analysis of the electrophoretic migration of individual exosomes and enables the accurate evaluation of the zeta potential distribution of exosomes, for the first time. From the experimental results, we found that there is a strong correlation between the average zeta potentials of exosomes and their cells of origin.

  17. Propagation of electro-kinetic waves in magnetized GaN semiconductor with nano-sized ion colloids

    SciTech Connect

    Saxena, Ajay; Sharma, Giriraj; Jat, K. L.; Rishi, M. P.

    2015-07-31

    Based on hydrodynamic model of multi-component plasma, an analytical study on propagation of longitudinal electro-kinetic (LEK) waves in wurtzite and zincblende structures of GaN is carried out. Nano-sized ion colloids (NICs) are embedded in the sample by the technique of ion-implantation. The implanted NICs are considered massive by an order as compared to the host lattice points and do not participate in Based LEK perturbations. Though, the NICs are continuously bombarded by the electrons as well as the holes yet, the former acquires a net negative charge owing to relatively higher mobility of electrons and consequently results into depletion of electron density in the medium. It i s found that the presence of charged NICs significantly modifies the dispersion and amplification characteristics of LEK waves in magnetized GaN semiconductor plasma and their role becomes increasingly effective as the fraction of charge on them increases.

  18. Experimental and numerical evidences of the observation of the Biot slow wave thanks to its electrokinetic conversion

    NASA Astrophysics Data System (ADS)

    Bordes, C.; Garambois, S.; Brito, D.; Dietrich, M.; Holzhauer, J.

    2013-12-01

    As originally described by Biot in 1956, seismic propagation in fluid-filled porous media should include two longitudinal contributions: the fast and slow P waves, the latest being commonly referred to as the ';Biot slow wave'. This seismic wave has been seldom observed in natural rocks at laboratory frequencies due to its low amplitude properties and has never been recognized at seismic frequencies due to its diffusive properties. In porous media, a part of seismic energy may also be converted into electromagnetic fields by a coupling phenomenon of electrokinetic nature: the so-called seismoelectric effect. Most seismoelectric studies focus on the observation of co-seismic or depth-converted electric fields generated by the propagation of fast P-waves, mainly to detect or to image new physico-chemical contrasts. Based on Pride's theory (1994), numerical modeling of seismo-electromagnetic wave propagation suggests that the observation of the Biot slow wave could be boosted by its electrokinetic conversion, i.e. that it would be easier to record the electric fields accompanying Biot slow waves generated by a mechanical source rather than the seismic fields. In order to confirm these numerical predictions, we designed a specific laboratory experiment involving a silica sand tank excited by using a homemade pneumatic seismic source. The investigated frequency range [0.5-5kHz] contains the Biot (transition) frequency separating the diffusive from the propagation regimes of the slow wave. Numerical seismoelectromagnetic experiments were also performed at this scale to compute the seismoelectric response in homogeneous and partially saturated sand with this acquisition configuration. The comparison of these experimental data to numerical results provides new perspectives for the detection, study and potential use of the Biot slow wave.

  19. Extraction, chromatographic and mass spectrometric methods for lipid analysis.

    PubMed

    Pati, Sumitra; Nie, Ben; Arnold, Robert D; Cummings, Brian S

    2016-05-01

    Lipids make up a diverse subset of biomolecules that are responsible for mediating a variety of structural and functional properties as well as modulating cellular functions such as trafficking, regulation of membrane proteins and subcellular compartmentalization. In particular, phospholipids are the main constituents of biological membranes and play major roles in cellular processes like transmembrane signaling and structural dynamics. The chemical and structural variety of lipids makes analysis using a single experimental approach quite challenging. Research in the field relies on the use of multiple techniques to detect and quantify components of cellular lipidomes as well as determine structural features and cellular organization. Understanding these features can allow researchers to elucidate the biochemical mechanisms by which lipid-lipid and/or lipid-protein interactions take place within the conditions of study. Herein, we provide an overview of essential methods for the examination of lipids, including extraction methods, chromatographic techniques and approaches for mass spectrometric analysis.

  20. Electrokinetic particle-electrode interactions at high frequencies

    NASA Astrophysics Data System (ADS)

    Yariv, Ehud; Schnitzer, Ory

    2013-01-01

    We provide a macroscale description of electrokinetic particle-electrode interactions at high frequencies, where chemical reactions at the electrodes are negligible. Using a thin-double-layer approximation, our starting point is the set of macroscale equations governing the “bounded” configuration comprising of a particle suspended between two electrodes, wherein the electrodes are governed by a capacitive charging condition and the imposed voltage is expressed as an integral constraint. In the large-cell limit the bounded model is transformed into an effectively equivalent “unbounded” model describing the interaction between the particle and a single electrode, where the imposed-voltage condition is manifested in a uniform field at infinity together with a Robin-type condition applying at the electrode. This condition, together with the standard no-flux condition applying at the particle surface, leads to a linear problem governing the electric potential in the fluid domain in which the dimensionless frequency ω of the applied voltage appears as a governing parameter. In the high-frequency limit ω≫1 the flow is dominated by electro-osmotic slip at the particle surface, the contribution of electrode electro-osmosis being O(ω-2) small. That simplification allows for a convenient analytical investigation of the prevailing case where the clearance between the particle and the adjacent electrode is small. Use of tangent-sphere coordinates allows to calculate the electric and flows fields as integral Hankel transforms. At large distances from the particle, along the electrode, both fields decay with the fourth power of distance.