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Sample records for automated anion-exchange purification

  1. New monolith technology for automated anion-exchange purification of nucleic acids.

    PubMed

    Thayer, J R; Flook, K J; Woodruff, A; Rao, S; Pohl, C A

    2010-04-15

    Synthetic nucleic acid analysis often employs pellicular anion-exchange (AE) chromatography because it supports very high efficiency separations while offering means to control secondary structure, retention and resolution by readily modifiable chromatographic conditions. However, these pellicular anion-exchange (pAE) phases do not offer capacity sufficient for lab-scale oligonucleotide (ON) purification. In contrast, monolithic phases produce fast separations at capacities exceeding their pellicular counterparts, but do not exhibit capacities typical of fully porous, bead-based, anion-exchangers. In order to further increase monolith capacity and obtain the selectivity and mass transfer characteristics of pellicular phases, a surface-functionalized monolith was coated with pAE nanobeads (latexes) usually employed on the pellicular DNAPac phase. The nanobead-coated monolith exhibited chromatographic behaviors typical of polymer AE phases. Based on this observation the monolithic substrate surface porosity and latex diameters were co-optimized to produce a hybrid monolith harboring capacity similar to that of fully porous bead-based phases and peak shape approaching that of the pAE phases. We tested the hybrid monolith on a variety of previously developed pAE capabilities including control of ON selectivity, resolution of derivatized ONs, the ability to resolve RNA ONs harboring aberrant linkages at different positions in a single sequence and separation of phosphorothioate diastereoisomers. We compared the yield and purity of an 8 mg ON sample purified on both the new hybrid monolith and a benchmark AE column based on fully porous monodisperse beads. This comparison included an assessment of the relative selectivities of both columns. Finally, we demonstrated the ability to couple AE ON separations with ESI-MS using an automated desalting protocol. This protocol is also useful for preparing ONs for other assays, such as enzyme treatments, that may be sensitive to

  2. Purification Or Organic Acids Using Anion Exchange Chromatography.

    DOEpatents

    Ponnampalam; Elankovan

    2001-09-04

    Disclosed is a cost-effective method for purifying and acidifying carboxylic acids, including organic acids and amino acids. The method involves removing impurities by allowing the anionic form of the carboxylic acid to bind to an anion exchange column and washing the column. The carboxylic anion is displaced as carboxylic acid by washing the resin with a strong inorganic anion. This method is effective in removing organic carboxylic acids and amino acids from a variety of industrial sources, including fermentation broths, hydrolysates, and waste streams.

  3. Improved recovery and purification of plutonium at Los Alamos using macroporous anion exchange resin

    SciTech Connect

    Marsh, S.F.; Mann, M.J.

    1987-05-01

    For almost 30 years, Los Alamos National Laboratory has used anion exchange in nitric acid as the major aqueous process or the recovery and purification of plutonium. One of the few disadvantages of this system is the particularly slow rate at which the anionic nitrato complex of Pu(IV) equilibrates with the resin. The Nuclear Materials Process Technology Group at Los Alamos recently completed an ion exchange development program that focused on improving the slow sorption kinetics that limits this process. A comprehensive investigation of modern anion exchange resins identified porosity and bead size as the properties that most influence plutonium sorption kinetics. Our study found that small beads of macroporous resin produced a dramatic increase in plutonium process efficiency. The Rocky Flats Plant has already adopted this improved ion exchange technology, and it currently is being evaluated for use in other DOE plutonium-processing facilities.

  4. Purification of plasmid DNA from Escherichia coli ferments using anion-exchange membrane and hydrophobic chromatography.

    PubMed

    Guerrero-Germán, Patricia; Montesinos-Cisneros, Rosa Ma; Prazeres, D Miguel F; Tejeda-Mansir, Armando

    2011-01-01

    A novel downstream bioprocess was developed to obtain purified plasmid DNA (pDNA) from Escherichia coli ferments. The intermediate recovery and purification of the pDNA in cell lysate was conducted using hollow-fiber tangential filtration and frontal anion-exchange membrane and elution hydrophobic chromatographies. The purity of the solutions of pDNA obtained during each process stage was investigated. The results show that the pDNA solution purity increased 30-fold and more than 99% of RNA in the lysate was removed during the process operations. The combination of membrane operations and hydrophobic interaction chromatography resulted in an efficient way to recover pDNA from cell lysates. A better understanding of membrane-based technology for the purification of pDNA from clarified E. coli lysate was developed in this research.

  5. High-performance purification of gelsolin from plasma using anion-exchange porous hollow-fiber membrane.

    PubMed

    Hagiwara, Kyohei; Yonedu, Shinji; Saito, Kyoichi; Shiraishi, Tomoyuki; Sugo, Takanobu; Tojyo, Tadashi; Katayama, Eisaku

    2005-07-25

    Gelsolin was purified from bovine plasma using an anion-exchange porous hollow-fiber membrane. The anion-change porous hollow-fiber membrane was prepared by radiation-induced graft polymerization of an epoxy-group-containing monomer, glycidyl methacrylate, and subsequent chemical modifications. Some of the epoxy groups of the polymer chain grafted onto the pore surface were converted into diethylamino groups, and the remaining epoxy groups were converted into 2-hydroxyethylamino groups. First, a gelsolin-containing dialyzed protein solution, prepared by pretreatments of ammonium sulfate precipitation and dialysis of plasma, was forced to permeate through the pores of an anion-exchange porous hollow-fiber membrane. Various proteins including gelsolin were adsorbed onto the anion-exchange polymer brush at a high rate with negligible diffusional mass-transfer resistance. Second, adsorbed gelsolin was specifically eluted by permeating 2mM calcium chloride. The amount of recovered gelsolin was 0.1 mg per 1 mL of plasma. Third, the remaining adsorbed proteins were quantitatively eluted with 1M sodium chloride, leading to a constant amount of recovered gelsolin during four cycles of purification. The total time required for gelsolin purification from 30 mL of bovine plasma was 11h, during which the time for selective adsorption of various proteins and affinity elution of gelsolin using the anion-exchange porous hollow-fiber membrane was 20 min.

  6. Anion-exchange purification of recombinant factor IX from cell culture supernatant using different chromatography supports.

    PubMed

    Ribeiro, Daniel A; Passos, Douglas F; Ferraz, Helen C; Castilho, Leda R

    2013-11-01

    Both recombinant and plasma-derived factor IX concentrates are used in replacement therapies for the treatment of haemophilia B. In the present work, the capture step for a recombinant FIX (rFIX) purification process was investigated. Different strong anion-exchange chromatography media (the resins Q Sepharose(®) FF and Fractogel(®) TMAE, the monolith CIM(®) QA and the membrane adsorber Sartobind(®) Q) were tested for their rFIX binding capacity under dynamic conditions. In these experiments, crude supernatant from CHO cells was used, thus in the presence of supernatant contaminants and mimicking process conditions. The highest dynamic binding capacity was obtained for the monolith, which was then further investigated. To study pseudoaffinity elution of functional rFIX with Ca(2+) ions, a design of experiments to evaluate the effects of pH, NaCl and CaCl2 on yield and purification factor was carried out. The effect of pH was not statistically significant, and a combination of no NaCl and 45mM CaCl2 yielded a good purification factor combined with a high yield of active rFIX. Under these conditions, activity yield of rFIX was higher than the mass yield, confirming selective elution of functional, γ-carboxylated rFIX. Scaling-up of this process 8 fold resulted in very similar process performance. Monitoring of the undesired activated FIX (FIXa) revealed that the FIXa/FIX ratio (1.94%) was higher in the eluate than in the loaded sample, but was still within an acceptable range. HCP and DNA clearances were high (1256 and 7182 fold, respectively), indicating that the proposed process is adequate for the intended rFIX capture step.

  7. Concentration and purification of enterovirus 71 using a weak anion-exchange monolithic column

    PubMed Central

    2014-01-01

    Background Enterovirus 71 (EV-71) is a neurotropic virus causing Hand, Foot and Mouth Disease (HFMD) in infants and children under the age of five. It is a major concern for public health issues across Asia-Pacific region. The most effective way to control the disease caused by EV-71 is by vaccination thus a novel vaccine is urgently needed. Inactivated EV-71 induces a strong, virus-neutralizing antibody response in animal models, protecting them against a lethal EV-71 challenge and it has been shown to elicit cross-neutralizing antibodies in human trials. Hence, the large-scale production of purified EV-71 is required for vaccine development, diagnosis and clinical trials. Methods CIM® Monolith columns are single-piece columns made up of poly(glycidyl methacrylate co-ethylene dimethacrylate) as support matrix. They are designed as porous channels rather than beads with different chemistries for different requirements. As monolithic columns have a high binding capacity, flow rate and resolution, a CIM® DEAE-8f tube monolithic column was selected for purification in this study. The EV-71 infected Rhabdomyosarcoma (RD) cell supernatant was concentrated using 8% PEG 8000 in the presence of 400 mM sodium chloride. The concentrated virus was purified by weak anion exchange column using 50 mM HEPES + 1 M sodium chloride as elution buffer. Results Highly pure viral particles were obtained at a concentration of 350 mM sodium chloride as confirmed by SDS-PAGE and electron microscopy. Presence of viral proteins VP1, VP2 and VP3 was validated by western blotting. The overall process achieved a recovery of 55%. Conclusions EV-71 viral particles of up to 95% purity can be recovered by a single step ion-exchange chromatography using CIM-DEAE monolithic columns and 1 M sodium chloride as elution buffer. Moreover, this method is scalable to purify several litres of virus-containing supernatant, using industrial monolithic columns with a capacity of up to 8 L such as

  8. Automated flow-based anion-exchange method for high-throughput isolation and real-time monitoring of RuBisCO in plant extracts.

    PubMed

    Suárez, Ruth; Miró, Manuel; Cerdà, Víctor; Perdomo, Juan Alejandro; Galmés, Jeroni

    2011-06-15

    In this work, a miniaturized, completely enclosed multisyringe-flow system is proposed for high-throughput purification of RuBisCO from Triticum aestivum extracts. The automated method capitalizes on the uptake of the target protein at 4°C onto Q-Sepharose Fast Flow strong anion-exchanger packed in a cylindrical microcolumn (105 × 4 mm) followed by a stepwise ionic-strength gradient elution (0-0.8 mol/L NaCl) to eliminate concomitant extract components and retrieve highly purified RuBisCO. The manifold is furnished downstream with a flow-through diode-array UV/vis spectrophotometer for real-time monitoring of the column effluent at the protein-specific wavelength of 280 nm to detect the elution of RuBisCO. Quantitation of RuBisCO and total soluble proteins in the eluate fractions were undertaken using polyacrylamide gel electrophoresis (PAGE) and the spectrophotometric Bradford assay, respectively. A comprehensive investigation of the effect of distinct concentration gradients on the isolation of RuBisCO and experimental conditions (namely, type of resin, column dimensions and mobile-phase flow rate) upon column capacity and analyte breakthrough was effected. The assembled set-up was aimed to critically ascertain the efficiency of preliminary batchwise pre-treatments of crude plant extracts (viz., polyethylenglycol (PEG) precipitation, ammonium sulphate precipitation and sucrose gradient centrifugation) in terms of RuBisCO purification and absolute recovery prior to automated anion-exchange column separation. Under the optimum physical and chemical conditions, the flow-through column system is able to admit crude plant extracts and gives rise to RuBisCO purification yields better than 75%, which might be increased up to 96 ± 9% with a prior PEG fractionation followed by sucrose gradient step.

  9. Modeling and simulation of anion-exchange membrane chromatography for purification of Sf9 insect cell-derived virus-like particles.

    PubMed

    Ladd Effio, Christopher; Hahn, Tobias; Seiler, Julia; Oelmeier, Stefan A; Asen, Iris; Silberer, Christine; Villain, Louis; Hubbuch, Jürgen

    2016-01-15

    Recombinant protein-based virus-like particles (VLPs) are steadily gaining in importance as innovative vaccines against cancer and infectious diseases. Multiple VLPs are currently evaluated in clinical phases requiring a straightforward and rational process design. To date, there is no generic platform process available for the purification of VLPs. In order to accelerate and simplify VLP downstream processing, there is a demand for novel development approaches, technologies, and purification tools. Membrane adsorbers have been identified as promising stationary phases for the processing of bionanoparticles due to their large pore sizes. In this work, we present the potential of two strategies for designing VLP processes following the basic tenet of 'quality by design': High-throughput experimentation and process modeling of an anion-exchange membrane capture step. Automated membrane screenings allowed the identification of optimal VLP binding conditions yielding a dynamic binding capacity of 5.7 mg/mL for human B19 parvovirus-like particles derived from Spodoptera frugiperda Sf9 insect cells. A mechanistic approach was implemented for radial ion-exchange membrane chromatography using the lumped-rate model and stoichiometric displacement model for the in silico optimization of a VLP capture step. For the first time, process modeling enabled the in silico design of a selective, robust and scalable process with minimal experimental effort for a complex VLP feedstock. The optimized anion-exchange membrane chromatography process resulted in a protein purity of 81.5%, a DNA clearance of 99.2%, and a VLP recovery of 59%.

  10. [Purification of immunoglobulin and serum albumin from serum via strong anion exchange chromatography coupled with molecular exclusion chromatography].

    PubMed

    Qin, Zonghua; Chen, Ting; Li, Renqiang

    2012-08-01

    The isoelectric points of immunoglobulin (Ig) and serum albumin (SA) in animal serum are about 7.8 and 4.8, respectively. Based on their larger difference of isoelectric points, Q Sepharose-XL strong anion exchange chromatography coupled with molecular exclusion chromatography was used to purify Ig and SA simultaneously from the high immune rabbit serum. After the Q Sepharose-XL strong anion exchange column was equilibrated with 0.02 mol/L Tris-HCl buffer of pH 8.0, a 10-fold dilution sample of rabbit serum was loaded onto the column and the pH gradient elution was performed. With the low flow rate of elution of 0.3 mL/min, the high-purity Ig was obtained when the elution pH was at 6.0. Continuously eluted at pH 4.0 with the same flow rate of elution, the SA was obtained and its purity was greater than 95% after molecular exclusion chromatography through Sephadex G-75. The purified Ig and SA were demonstrated to maintain normal activities by activity analysis. The results of protein content showed that the purification recoveries of Ig and SA were over 95% and 90%, respectively. The method has the advantages of simple operation and rapidity, and the Ig and SA purified simultaneously from the animal serum could maintain normal activities.

  11. Simultaneous clarification of Escherichia coli culture and purification of extracellularly produced penicillin G acylase using tangential flow filtration and anion-exchange membrane chromatography (TFF-AEMC).

    PubMed

    Orr, Valerie; Scharer, Jeno; Moo-Young, Murray; Honeyman, C Howie; Fenner, Drew; Crossley, Lisa; Suen, Shing-Yi; Chou, C Perry

    2012-07-01

    Downstream purification often represents the most cost-intensive step in the manufacturing of recombinant proteins since conventional purification processes are lengthy, technically complicated, and time-consuming. To address this issue, herein we demonstrated the simultaneous clarification and purification of the extracellularly produced recombinant protein by Escherichia coli using an integrated system of tangential flow filtration and anion exchange membrane chromatography (TFF-AEMC). After cultivation in a bench-top bioreactor with 1L working volume using the developed host/vector system for high-level expression and effective secretion of recombinant penicillin G acylase (PAC), the whole culture broth was applied directly to the established system. One-step purification of recombinant PAC was achieved based on the dual nature of membrane chromatography (i.e. microfiltration-sized pores and anion-exchange chemistry) and cross-flow operations. Most contaminant proteins in the extracellular medium were captured by the anion-exchange membrane and cells remained in the retentate, whereas extracellular PAC was purified and collected in the filtrate. The batch time for both cultivation and purification was less than 24h and recombinant PAC with high purity (19 U/mg), yield (72% recovery), and productivity (41 mg of purified PAC per liter of culture) was obtained. Due to the nature of the non-selective protein secretion system and the versatility of ion-exchange membrane chromatography, the developed system can be widely applied for effective production and purification of recombinant proteins.

  12. HB-LINE ANION EXCHANGE PURIFICATION OF AFS-2 PLUTONIUM FOR MOX

    SciTech Connect

    Kyser, E. A.; King, W. D.

    2012-07-31

    Non-radioactive cerium (Ce) and radioactive plutonium (Pu) anion exchange column experiments using scaled HB-Line designs were performed to investigate the feasibility of using either gadolinium nitrate (Gd) or boric acid (B as H{sub 3}BO{sub 3}) as a neutron poison in the H-Canyon dissolution process. Expected typical concentrations of probable impurities were tested and the removal of these impurities by a decontamination wash was measured. Impurity concentrations are compared to two specifications - designated as Column A or Column B (most restrictive) - proposed for plutonium oxide (PuO{sub 2}) product shipped to the Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF). Use of Gd as a neutron poison requires a larger volume of wash for the proposed Column A specification. Since boron (B) has a higher proposed specification and is more easily removed by washing, it appears to be the better candidate for use in the H-Canyon dissolution process. Some difficulty was observed in achieving the Column A specification due to the limited effectiveness that the wash step has in removing the residual B after ~4 BV's wash. However a combination of the experimental 10 BV's wash results and a calculated DF from the oxalate precipitation process yields an overall DF sufficient to meet the Column A specification. For those impurities (other than B) not removed by 10 BV's of wash, the impurity is either not expected to be present in the feedstock or process, or recommendations have been provided for improvement in the analytical detection/method or validation of calculated results. In summary, boron is recommended as the appropriate neutron poison for H-Canyon dissolution and impurities are expected to meet the Column A specification limits for oxide production in HB-Line.

  13. HB-LINE ANION EXCHANGE PURIFICATION OF AFS-2 PLUTONIUM FOR MOX

    SciTech Connect

    Kyser, E.; King, W.

    2012-04-25

    Non-radioactive cerium (Ce) and radioactive plutonium (Pu) anion exchange column experiments using scaled HB-Line designs were performed to investigate the feasibility of using either gadolinium nitrate (Gd) or boric acid (B as H{sub 3}BO{sub 3}) as a neutron poison in the H-Canyon dissolution process. Expected typical concentrations of probable impurities were tested and the removal of these impurities by a decontamination wash was measured. Impurity concentrations are compared to two specifications - designated as Column A or Column B (most restrictive) - proposed for plutonium oxide (PuO{sub 2}) product shipped to the Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF). Use of Gd as a neutron poison requires a larger volume of wash for the proposed Column A specification. Since boron (B) has a higher proposed specification and is more easily removed by washing, it appears to be the better candidate for use in the H-Canyon dissolution process. Some difficulty was observed in achieving the Column A specification due to the limited effectiveness that the wash step has in removing the residual B after {approx}4 BV's wash. However a combination of the experimental 10 BV's wash results and a calculated DF from the oxalate precipitation process yields an overall DF sufficient to meet the Column A specification. For those impurities (other than B) not removed by 10 BV's of wash, the impurity is either not expected to be present in the feedstock or process, or recommendations have been provided for improvement in the analytical detection/method or validation of calculated results. In summary, boron is recommended as the appropriate neutron poison for H-Canyon dissolution and impurities are expected to meet the Column A specification limits for oxide production in HB-Line.

  14. Strong anion-exchange fast performance liquid chromatography as a versatile tool for preparation and purification of RNA produced by in vitro transcription.

    PubMed

    Koubek, Jiri; Lin, Ku Feng; Chen, Yet Ran; Cheng, Richard Ping; Huang, Joseph Jen Tse

    2013-10-01

    Here we demonstrate the use of strong anion-exchange fast performance liquid chromatography (FPLC) as a simple, fast, and robust method for RNA production by in vitro transcription. With this technique, we have purified different transcription templates from unreacted reagents in large quantities. The same buffer system could be used to readily remove nuclease contamination from the overexpressed pyrophosphatase, the important reagent for in vitro transcription. In addition, the method can be used to monitor in vitro transcription reactions to enable facile optimization of reaction conditions, and we have compared the separation performance between strong and weak anion-exchange FPLC for various transcribed RNAs, including the Diels-Alder ribozyme, the hammerhead ribozyme tRNA, and 4.5S RNA. The functionality of the purified tRNA(Cys) has been confirmed by the aminoacylation assay. Only the purification by strong anion-exchange FPLC has led to the enrichment of the functional tRNA from run-off transcripts as revealed by both enzymatic and electrophoretic analysis.

  15. A simple and efficient purification platform for monoclonal antibody production based on chromatin-directed cell culture clarification integrated with precipitation and void-exclusion anion exchange chromatography.

    PubMed

    Chen, Quan; Abdul Latiff, Sarah Maria; Toh, Phyllicia; Peng, Xinying; Hoi, Aina; Xian, Mo; Zhang, Haibo; Nian, Rui; Zhang, Wei; Gagnon, Pete

    2016-10-20

    Protein A affinity chromatography, featured by its robustness and high-specificity, is still dominant as a first capture step for the purification of immunoglobulin G monoclonal antibodies (IgG mAbs). However, the material and operational costs of protein A are universally recognized as high, and its productivity is also limited as column mode. In order to overcome these limitations, industry is increasingly considering the use of non-protein A-based processes for IgG purification. In this study, sodium citrate precipitation (SCP) was developed as the primary purification step, and chromatin-directed cell culture clarification was demonstrated to significantly elevate the purification capability. Additional 0.05% (w/v) of Tween 20 was shown to effectively reduce the residual free antibody light chain (LC) during precipitation. The resuspended IgG was further polished by void-exclusion anion exchange chromatography (VEAX), which supported protein loading without buffer adjustment. The non-histone host cell protein (nh-HCP) content in the final product was about 5ppm and histone HCP below limit of detection (LOD). DNA was reduced to less than 1ppb, and aggregates/free LC less than 0.1%. The overall IgG recovery was 87.2%. A simple and efficient purification platform with only one-column step was therefore established, providing a more promising alternative to the current prevailing protein A-based purification platforms.

  16. Anion exchange membrane

    DOEpatents

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  17. Fully automated protein purification

    PubMed Central

    Camper, DeMarco V.; Viola, Ronald E.

    2009-01-01

    Obtaining highly purified proteins is essential to begin investigating their functional and structural properties. The steps that are typically involved in purifying proteins can include an initial capture, intermediate purification, and a final polishing step. Completing these steps can take several days and require frequent attention to ensure success. Our goal was to design automated protocols that will allow the purification of proteins with minimal operator intervention. Separate methods have been produced and tested that automate the sample loading, column washing, sample elution and peak collection steps for ion-exchange, metal affinity, hydrophobic interaction and gel filtration chromatography. These individual methods are designed to be coupled and run sequentially in any order to achieve a flexible and fully automated protein purification protocol. PMID:19595984

  18. LAB-SCALE DEMONSTRATION OF PLUTONIUM PURIFICATION BY ANION EXCHANGE, PLUTONIUM (IV) OXALATE PRECIPITATION, AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

    SciTech Connect

    Crowder, M.; Pierce, R.

    2012-08-22

    H-Canyon and HB-Line are tasked with the production of PuO{sub 2} from a feed of plutonium metal. The PuO{sub 2} will provide feed material for the MOX Fuel Fabrication Facility. After dissolution of the Pu metal in H-Canyon, the solution will be transferred to HB-Line for purification by anion exchange. Subsequent unit operations include Pu(IV) oxalate precipitation, filtration and calcination to form PuO{sub 2}. This report details the results from SRNL anion exchange, precipitation, filtration, calcination, and characterization tests, as requested by HB-Line1 and described in the task plan. This study involved an 80-g batch of Pu and employed test conditions prototypical of HB-Line conditions, wherever feasible. In addition, this study integrated lessons learned from earlier anion exchange and precipitation and calcination studies. H-Area Engineering selected direct strike Pu(IV) oxalate precipitation to produce a more dense PuO{sub 2} product than expected from Pu(III) oxalate precipitation. One benefit of the Pu(IV) approach is that it eliminates the need for reduction by ascorbic acid. The proposed HB-Line precipitation process involves a digestion time of 5 minutes after the time (44 min) required for oxalic acid addition. These were the conditions during HB-line production of neptunium oxide (NpO{sub 2}). In addition, a series of small Pu(IV) oxalate precipitation tests with different digestion times were conducted to better understand the effect of digestion time on particle size, filtration efficiency and other factors. To test the recommended process conditions, researchers performed two nearly-identical larger-scale precipitation and calcination tests. The calcined batches of PuO{sub 2} were characterized for density, specific surface area (SSA), particle size, moisture content, and impurities. Because the 3013 Standard requires that the calcination (or stabilization) process eliminate organics, characterization of PuO{sub 2} batches monitored the

  19. Anion exchange polymer electrolytes

    DOEpatents

    Kim, Yu Seung; Kim, Dae Sik; Lee, Kwan-Soo

    2013-07-23

    Solid anion exchange polymer electrolytes and compositions comprising chemical compounds comprising a polymeric core, a spacer A, and a guanidine base, wherein said chemical compound is uniformly dispersed in a suitable solvent and has the structure: ##STR00001## wherein: i) A is a spacer having the structure O, S, SO.sub.2, --NH--, --N(CH.sub.2).sub.n, wherein n=1-10, --(CH.sub.2).sub.n--CH.sub.3--, wherein n=1-10, SO.sub.2-Ph, CO-Ph, ##STR00002## wherein R.sub.5, R.sub.6, R.sub.7 and R.sub.8 each are independently --H, --NH.sub.2, F, Cl, Br, CN, or a C.sub.1-C.sub.6 alkyl group, or any combination of thereof; ii) R.sub.9, R.sub.10, R.sub.11, R.sub.12, or R.sub.13 each independently are --H, --CH.sub.3, --NH.sub.2, --NO, --CH.sub.nCH.sub.3 where n=1-6, HC.dbd.O--, NH.sub.2C.dbd.O--, --CH.sub.nCOOH where n=1-6, --(CH.sub.2).sub.n--C(NH.sub.2)--COOH where n=1-6, --CH--(COOH)--CH.sub.2--COOH, --CH.sub.2--CH(O--CH.sub.2CH.sub.3).sub.2, --(C.dbd.S)--NH.sub.2, --(C.dbd.NH)--N--(CH.sub.2).sub.nCH.sub.3, where n=0-6, --NH--(C.dbd.S)--SH, --CH.sub.2--(C.dbd.O)--O--C(CH.sub.3).sub.3, --O--(CH.sub.2).sub.n--CH--(NH.sub.2)--COOH, where n=1-6, --(CH.sub.2).sub.n--CH.dbd.CH wherein n=1-6, --(CH.sub.2).sub.n--CH--CN wherein n=1-6, an aromatic group such as a phenyl, benzyl, phenoxy, methylbenzyl, nitrogen-substituted benzyl or phenyl groups, a halide, or halide-substituted methyl groups; and iii) wherein the composition is suitable for use in a membrane electrode assembly.

  20. Pu Anion Exchange Process Intensification

    SciTech Connect

    Taylor-Pashow, K.

    2015-10-08

    This project seeks to improve the efficiency of the plutonium anion-exchange process for purifying Pu through the development of alternate ion-exchange media. The objective of the project in FY15 was to develop and test a porous foam monolith material that could serve as a replacement for the current anion-exchange resin, Reillex® HPQ, used at the Savannah River Site (SRS) for purifying Pu. The new material provides advantages in efficiency over the current resin by the elimination of diffusive mass transport through large granular resin beads. By replacing the large resin beads with a porous foam there is much more efficient contact between the Pu solution and the anion-exchange sites present on the material. Several samples of a polystyrene based foam grafted with poly(4-vinylpyridine) were prepared and the Pu sorption was tested in batch contact tests.

  1. Anion exchange resins: Structure, formulation, and applications. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    Not Available

    1994-07-01

    The bibliography contains citations concerning the formulation and synthesis of anion exchange resins based on such resins as amides, polyethylenes, and styrenes. Osmotic, sorption, and electrical properties; exchange kinetics behavior; structure studies; and temperature related performance effects on anion exchange resins are considered. Anion exchange chromatography of liquids, and applications in water purification, pollution control, and protein and metallic ion separation are included. (Contains a minimum of 222 citations and includes a subject term index and title list.)

  2. Evolution of volatile substances from strongly basic anion-exchangers into the gas phase

    SciTech Connect

    Ryabikina, L.G.; Afanas'eva, E.K.; Vulkih, A.I.; Yakovlev, A.I.

    1985-05-10

    The purpose of this work was chemical evaluation, from the sanitary standpoint, of strongly basic anion-exchangers and of polyacrylonitrile fibers filled with them, in relation to their use for purification of air intended for human respiration. The carbonate forms of granulated anion-exchange resins AV-17-8 and AV-29-10P and fibers filled with them were investigated. Amines were determined spectrophotometrically. It is determined that the sanitary chemical characteristics of PAN fibers filled with strongly basic anion-exchangers of the polymerization type make them suitable for removing substances which have no destructive effects on the resins from air.

  3. Advancements in Anion Exchange Membrane Cations

    SciTech Connect

    Sturgeon, Matthew R.; Long, Hai; Park, Andrew M.; Pivovar, Bryan S.

    2015-10-15

    Anion-exchange membrane fuel cells (AME-FCs) are of increasingly popular interest as they enable the use of non-Pt fuel cell catalysts, the primary cost limitation of proton exchange membrane fuel cells. Benzyltrimethyl ammonium (BTMA) is the standard cation that has historically been utilized as the hydroxide conductor in AEMs. Herein we approach AEMs from two directions. First and foremost we study the stability of several different cations in a hydroxide solution at elevated temperatures. We specifically targeted BTMA and methoxy and nitro substituted BTMA. We've also studied the effects of adding an akyl spacer units between the ammonium cation and the phenyl group. In the second approach we use computational studies to predict stable ammonium cations, which are then synthesized and tested for stability. Our unique method to study cation stability in caustic conditions at elevated temperatures utilizes Teflon Parr reactors suitable for use under various temperatures and cation concentrations. NMR analysis was used to determine remaining cation concentrations at specific time points with GCMS analysis verifying product distribution. We then compare the experimental results with calculated modeling stabilities. Our studies show that the electron donating methoxy groups slightly increase stability (compared to that of BTMA), while the electron withdrawing nitro groups greatly decrease stability in base. These results give insight into possible linking strategies to be employed when tethering a BTMA like ammonium cation to a polymeric backbone; thus synthesizing an anion exchange membrane.

  4. Donnan dialysis of copper, gold and silver cyanides with various anion exchange membranes.

    PubMed

    Akretche, D E; Kerdjoudj, H

    2000-02-07

    Donnan dialysis is an ion exchange membrane process that can be used for the purification and concentration of diluted solutions. In this work, the behaviour of gold, silver and copper in cyanide medium is examined. Flux of cyanide complexes and corresponding free cyanide are determined using five commercial anion exchanger membranes (AMV, ACS, RAI 5035, ADP and ADS). The results show that the rate transfer depends upon the nature of the anion exchanger membrane. It is observed that the species number in the feed solution influences the transfer selectivity of metal ion complex against free cyanide Thus, gold which forms only one stable species with cyanides is transferred faster through an ACS membrane than copper which forms three species. However, this result is not verified when an ADS membrane is used. A model of the complex transfer through anion exchange membranes based on Donnan dialysis is proposed. A three compartment Donnan dialysis is performed to improve the separation between the studied metals. Decyanidation is also examined and separation factors are calculated. It is shown that Donnan dialysis can be an efficient technique for the separation of cyanides complexes of copper, gold and silver when parameters such as anion exchange membrane and the number of compartments are optimised. An advantage of this technique is also the possibility of recycling all reactants with a good impact on the environment.

  5. 8. VIEW OF GLOVE BOXES USED IN THE ANION EXCHANGE ...

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

    8. VIEW OF GLOVE BOXES USED IN THE ANION EXCHANGE PROCESS. THE ANION EXCHANGE PROCESS PURIFIED AND CONCENTRATED PLUTONIUM-BEARING NITRIC ACID SOLUTIONS TO MAKE THEM ACCEPTABLE AS FEED FOR CONVERSION TO METAL. (6/20/60) - Rocky Flats Plant, Plutonium Recovery & Fabrication Facility, North-central section of plant, Golden, Jefferson County, CO

  6. "Salt tolerant" anion exchange chromatography for direct capture of an acidic protein from CHO cell culture.

    PubMed

    Champagne, Jérôme; Balluet, Guillaume; Gantier, René; Toueille, Magali

    2013-06-01

    The present study describes the use of the new HyperCel STAR AX "salt tolerant" anion exchange sorbent for the capture from Chinese Hamster Ovary (CHO) cell culture supernatant (CCS) of an acidic model protein (α-amylase). HyperCel STAR AX sorbent and other conventional anion exchangers were evaluated to purify biologically-active enzyme. Salt tolerance of the sorbent allowed reaching 5-fold higher dynamic binding capacity than conventional anion exchange during capture of the enzyme from neat (undiluted) CCS. After optimization of operating conditions, HyperCel STAR AX turned out to be the only sorbent allowing efficient protein capture directly from both neat and diluted CCS with consistent and satisfying purity, yield and productivity. Therefore implementation of the salt tolerant sorbent in industrial purification processes should allow avoiding time and cost consuming steps such as dilution or UF/DF that exclusively aim at establishing suitable conditions for ion exchange step without bringing any added value to the purification process performance. Altogether this study highlights the flexibility and cost-reduction potential brought in process design by the HyperCel STAR AX salt tolerant sorbent.

  7. Adsorption of plasmid DNA on anion exchange chromatography media.

    PubMed

    Tarmann, Christina; Jungbauer, Alois

    2008-08-01

    Anion exchange chromatography (AEC) is a useful and effective tool for DNA purification, but due to average pore sizes between 40 and 100 nm most AEC resins lack truly useful binding capacities for plasmid DNA (pDNA). Equilibrium binding capacities and uptake kinetics of AEC media including conventional media (Source 30 Q, Q Sepharose HP), a polymer grafted medium (Fractogel EMD DEAE (M)), media with large pores (Celbeads DEAE, PL SAX 4000 A 30 microm) and a monolithic medium (CIM-DEAE) were investigated by batch uptake or shallow bed experiments at two salt concentrations. Theoretical and experimental binding capacities suggest that the shape of the pDNA molecule can be described by a rod with a length to diameter ratio of 20:1 and that the molecule binds in upright position. The arrangement of DNA like a brush at the surface can be considered as entropy driven, kind of self-assembly process which is inherent to highly and uniformly charged DNA molecules. The initial phase of adsorption is very fast and levels off, associated with a change in mass transfer mechanism. Feed concentrations higher than 0.1 mg/mL pDNA pronounce this effect. Monolithic media showed the fastest adsorption rate and highest binding capacity with 13 mg pDNA per mL.

  8. Determination of uranium isotopes in environmental samples by anion exchange in sulfuric and hydrochloric acid media.

    PubMed

    Popov, L

    2016-09-01

    Method for determination of uranium isotopes in various environmental samples is presented. The major advantages of the method are the low cost of the analysis, high radiochemical yields and good decontamination factors from the matrix elements, natural and man-made radionuclides. The separation and purification of uranium is attained by adsorption with strong base anion exchange resin in sulfuric and hydrochloric acid media. Uranium is electrodeposited on a stainless steel disk and measured by alpha spectrometry. The analytical method has been applied for the determination of concentrations of uranium isotopes in mineral, spring and tap waters from Bulgaria. The analytical quality was checked by analyzing reference materials.

  9. Predicting Carbonate Species Ionic Conductivity in Alkaline Anion Exchange Membranes

    DTIC Science & Technology

    2012-06-01

    anion exchange membranes. Andrew M. Kiss, Timothy D . Myles, Kyle N. Grew, Aldo A. Peracchio, George J. Nelson, and Wilson K. S. Chiu University of...Alkaline Anion Exchange Membranes Andrew M. Kiss1, Timothy D . Myles1, Kyle N. Grew2, Aldo A. Peracchio1, George J. Nelson1, and Wilson K. S. Chiu1* 1...Vol. 301, 93-106, 2007. 16. Satterfleld,M.B., Benziger,J.B., J. Phys. Chem. B, Vol. 112,12, 3693 -3704, 2008. 17. Motupally,S., Becker,A.J

  10. Contamination of an anion-exchange membrane by glutathione.

    PubMed

    Gotoh, T; Kikuchi, K

    2000-01-01

    Electrodialysis, which can separate electrolytes under mild conditions by using ion-exchange membranes, is a strong candidate for separation of GSH from yeast extracts, because GSH is unstable and easily oxidized forming a disulfide bond especially under alkali conditions. In this paper, sorption behavior of GSH on an anion-exchange membrane, in the pH 3-6 region that is expected to be the most preferable for its electro-dialytic separation, was examined. Sorption of GSH on a Selemion-AMV anion-exchange membrane was accelerated as the pH of the membrane-contact solution increased, and there was a good correlation between the sorbed amounts and the molar fraction of monovalent anionic species of GSH. However, the amounts of GSH desorbed from the membrane by a NaCl desorbing solution were much lower than the initial sorbed amounts, and the difference between them was enlarged with increasing pH. The GSH which was lost could be recovered by the addition of DTT in the membrane-contact and desorbing solutions. Similar results were also obtained with Cys. We thus concluded that an anion-exchange membrane would be contaminated by thiol compounds, such as GSH and Cys, through oxidative binding of the thiol group with the membrane, the local OH- concentration in which was enhanced due to attraction by the positively charged anion-exchange membrane.

  11. Automated RNA Extraction and Purification for Multiplexed Pathogen Detection

    SciTech Connect

    Bruzek, Amy K.; Bruckner-Lea, Cindy J.

    2005-01-01

    Pathogen detection has become an extremely important part of our nation?s defense in this post 9/11 world where the threat of bioterrorist attacks are a grim reality. When a biological attack takes place, response time is critical. The faster the biothreat is assessed, the faster countermeasures can be put in place to protect the health of the general public. Today some of the most widely used methods for detecting pathogens are either time consuming or not reliable [1]. Therefore, a method that can detect multiple pathogens that is inherently reliable, rapid, automated and field portable is needed. To that end, we are developing automated fluidics systems for the recovery, cleanup, and direct labeling of community RNA from suspect environmental samples. The advantage of using RNA for detection is that there are multiple copies of mRNA in a cell, whereas there are normally only one or two copies of DNA [2]. Because there are multiple copies of mRNA in a cell for highly expressed genes, no amplification of the genetic material may be necessary, and thus rapid and direct detection of only a few cells may be possible [3]. This report outlines the development of both manual and automated methods for the extraction and purification of mRNA. The methods were evaluated using cell lysates from Escherichia coli 25922 (nonpathogenic), Salmonella typhimurium (pathogenic), and Shigella spp (pathogenic). Automated RNA purification was achieved using a custom sequential injection fluidics system consisting of a syringe pump, a multi-port valve and a magnetic capture cell. mRNA was captured using silica coated superparamagnetic beads that were trapped in the tubing by a rare earth magnet. RNA was detected by gel electrophoresis and/or by hybridization of the RNA to microarrays. The versatility of the fluidics systems and the ability to automate these systems allows for quick and easy processing of samples and eliminates the need for an experienced operator.

  12. Determination of sulphide by anion-exchange with lead iodate.

    PubMed

    Verma, K K; Gupta, D; Sanghi, S K; Jain, A

    1988-11-01

    A quick anion-exchange reaction, suitable for the determination of sulphide, has been found to occur on stirring a suspension of lead iodate (solubility product, K(s0) = 1.2 x 10(-13)) with sulphide solution at pH 5-8. After removal of the precipitates of lead iodate and lead sulphide (K(s0) = 3.4 x 10(-28)), the iodate released can be determined by its reaction with acidified iodide to give tri-iodide which is either titrated with thiosulphate or measured spectrophotometrically as its blue complex with starch. Chloride, bromide, iodide, fluoride, oxalate, sulphate, thiocyanate and phosphate do not interfere. Thiosulphate, sulphite, nitrite and thiols do not give an anion-exchange reaction but do interfere in the redox reaction of iodate with acidified iodide. However, this is avoided if they are first oxidized with bromine (the liberated iodate remains unaffected before iodometry.

  13. Highly Water Resistant Anion Exchange Membrane for Fuel Cells.

    PubMed

    Yang, Zhengjin; Hou, Jianqiu; Wang, Xinyu; Wu, Liang; Xu, Tongwen

    2015-07-01

    For anion exchange membranes (AEMs), achieving efficient hydroxide conductivity without excessive hydrophilicity presents a challenge. Hence, new strategies for constructing mechanically strengthened and hydroxide conductive (especially at controlled humidity) membranes are critical for developing better AEMs. Macromolecular modification involving ylide chemistry (Wittig reaction) for the fabrication of novel AEMs with an interpenetrating polymer network structure is reported. The macromolecular modification is cost effective, facile, and based on a one-pot synthesis. AEM water uptake is reduced to 3.6 wt% and a high hydroxide conductivity (69.7 mS cm(-1) , 90 °C) is achieved simultaneously. More importantly, the membrane exhibits similar tensile strength (>35 MPa) and comparable flexibility in both dry and wet states. These AEMs could find further applications within anion exchange membrane fuel cells with low humidity or photoelectric assemblies.

  14. New stationary phase for anion-exchange chromatography.

    PubMed

    Auler, Lúcia M L A; Silva, César R; Collins, Kenneth E; Collins, Carol H

    2005-05-06

    This work describes the preparation of an anion-exchange phase based on silica, using a two-step modification process. First, 10 microm Davisil silica particles were silanized with chloropropyltrimethoxysilane to yield chloropropyl silica. The modified silica was then reacted with pyridine to produce positively charged propylpyridinium groups on the surface, the anion-exchange sites. The phase was characterized by thermogravimetric analysis and infrared and solid state 13C and 29Si NMR spectroscopies. HPLC separations of common inorganic anions, including chloride, nitrite, bromide and nitrate, were performed using 150 x 3.9 HPLC columns packed with the phase, using a phthalate buffer solution as mobile phase with non-suppressed conductivity detection. Efficiency and resolution were calculated and the results show that the new phase has significant promise for the analysis of these anions in environmental samples.

  15. A method for production of new anion exchangers

    NASA Astrophysics Data System (ADS)

    Behrendt, G.; Hunger, H. D.

    1991-12-01

    The invention relates to a method for the production of new anion exchangers that can be used in molecular biology, genetic engineering, biotechnology, and phytopathology. According to the invention, halogen-containing polyurethanes are reacted with one or more tertiary amines. By the method, polyurethane shapes with positive surface charges are produced from preformed shapes, with preservation of the form and properties thereof. The products have thermally stable bonds with biomolecules together with high binding capacity.

  16. Mechanical Characterization of Anion Exchange Membranes Under Controlled Environmental Conditions

    DTIC Science & Technology

    2015-05-11

    membranes (AEM) have the potential to dramatically lower the cost of fuel cells by utilizing non-noble catalysts and a variety of fuel sources. Although...the cost of fuel cells by utilizing non-noble catalysts and a variety of fuel sources. Although chemical degradation typically dominates membrane...anion exchange membranes (AEM) have the potential to dramatically lower the cost of fuel cells by utilizing non-noble catalysts and a variety of

  17. Collection of ambient air phenols using an anion exchange membrane

    SciTech Connect

    Nishioka, M.; Burkholder, H.; Reynolds, S.; Burdick, N.; Pleil, J.

    1994-12-31

    The authors have previously demonstrated the feasibility of collecting vapor phase ambient air phenols by reversible chemical reaction with a solid sorbent. The authors report here enhanced detection limits for ambient phenols using an anion exchange membrane that allows high collection efficiency at 10 L/min sampling rate. The membrane consists of 5 {micro}m particles of the anion exchange resin enmeshed in a Teflon microfibril matrix. This membrane is similar to Empore membranes, with the addition of the anion exchange capacity. Sampling is accomplished using a 10.5 cm (diameter) membrane and a General Metal Works PS-1 sampler. A Teflon-coated glass fiber filter, spiked with deutered phenols, and placed ahead of the membrane, is used to deliver these surrogate recovery standards to the membrane during the sampling. Following sampling, membranes are shaken gently in an acidified mixture of methanol and dichloromethane. The extract is derivatized with BSTFA and analyzed using either GC/FID or EI GC/MS. Analytical methodology allows detection at the 0.02 ppbv level for 12 hrs of sampling ({approximately} 0.1 {micro}g/m{sup 3}).

  18. Comparison among three anion exchange chromatographic supports to capture erythropoietin from cell culture supernatant.

    PubMed

    Hernández, Lourdes; Stewart, Diobel; Zumalacárregui, Lourdes; Amaro, Daniel

    2015-06-01

    Affinity and ion exchange conventional chromatography have been used to capture erythropoietin (EPO) from mammalian cell culture supernatant. Currently, chromatographic adsorbent perfusion is available, however a limited number of applications have been found in the literature. In this work, three anion exchange chromatographic supports (gel, membrane and monolithic) were evaluated in the capture step of the recombinant erythropoietin purification process. The influences of load and flow rate on each support performance were analyzed. Also the purity of the EPO molecules was determined. A productivity analysis, as a decision tool for larger scale implementation, was done. As a conclusion, the evaluated supports are technically suitable to capture EPO with adequate recovery and good purity. However, the monolithic column admits high operating velocity, showing the highest adsorption capacity and productivity.

  19. [Separation of coagulation factor VIII with high activity using gigaporous anion exchange chromatography].

    PubMed

    Kang, Limei; Zhang, Yan; Luo, Jian; Li, You; Zhou, Yuefang; Yu, Rong; Su, Zhiguo

    2012-06-01

    A purification process to obtain coagulation factor VIII (F VIII) with high activity from human plasma was established. Based on the analysis of the size ratio between F VIII and matrix porous medium and its effect on the protein activity, a novel purification process designed was superporous ion exchange chromatography (IEC). The operating conditions of gigaporous and traditional anion exchange chromatography were optimized separately. The chromogenic substrate, gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to monitor the bioactivity and purity of the chromatographic products. The results showed that the superporous medium could not only protect structure of macro-protein but also enhance its mass transfer, finally giving FVIII product with high activity. The yield of F VIII in superporous chromatography was about five times of commercially agarose chromatography and the specific activity was up to 154 IU/mg protein. Furthermore, we studied the regeneration process of the superporous medium, washing the column with 5 column volumes of 1 mol/L NaOH at a low flow rate, to ensure the chromatographic stability. This purification process is simple, reproducible and suitable for large-scale production.

  20. Anion Exchange Membranes: Current Status and Moving Forward

    SciTech Connect

    Hickner, MA; Herring, AM; Coughlin, EB

    2013-10-29

    This short review is meant to provide the reader with highlights in anion exchange membrane research, describe current needs in the field, and point out promising directions for future work. Anion exchange membranes (AEMs) provide one possible route to low platinum or platinum-free fuel cells with the potential for facile oxidation of complex fuels beyond hydrogen and methanol. AEMs and related stable cationic polymers also have applications in energy storage and other electrochemical technologies such as water electrolyzers and redox flow batteries. While anion exchange membranes have been known for a long time in water treatment applications, materials for electrochemical technology with robust mechanical properties in thin film format have only recently become more widely available. High hydroxide and bicarbonate anion conductivity have been demonstrated in a range of AEM formats, but intrinsic stability of the polymers and demonstration of long device lifetime remain major roadblocks. Novel approaches to stable materials have focused on new types of cations that employ delocalization and steric shielding of the positive center to mitigate nucleophilic attack by hydroxide. A number of promising polymer backbones and membrane architectures have been identified, but limited device testing and a lack of understanding of the degradation mechanisms in operating devices is slowing progress on engineered systems with alkaline fuel cell technology. Our objective is to spur more research in this area to develop fuel cell systems that approach the costs of inexpensive batteries for large-scale applications. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1727-1735, 2013

  1. Preparation of pure, high titer, pseudoinfectious Flavivirus particles by hollow fiber tangential flow filtration and anion exchange chromatography.

    PubMed

    Mundle, Sophia T; Giel-Moloney, Maryann; Kleanthous, Harry; Pugachev, Konstantin V; Anderson, Stephen F

    2015-08-20

    Purification of enveloped viruses such as live flavivirus vaccine candidates poses a challenge as one must retain viral infectivity to preserve immunogenicity. Here we describe a laboratory-scale purification procedure for two replication defective (single-cycle) flavivirus variants for use in a pre-clinical setting. The two step purification scheme based on hollow fiber tangential flow filtration (TFF) followed by anion exchange chromatography using convective interaction media (CIM(®)) monoliths results in a ∼60% recovery of infectious virus titer and can be used to prepare nearly homogenous, highly purified vaccine viruses with titers as high as 1×10(9) focus forming units per mL. Flavivirus virions prepared by this method are 2 and 3 orders of magnitude more pure with respect to dsDNA and BHK host cell proteins, respectively, as compared to the raw feed stream.

  2. Anion-exchange nanospheres as titration reagents for anionic analytes.

    PubMed

    Zhai, Jingying; Xie, Xiaojiang; Bakker, Eric

    2015-08-18

    We present here anion-exchange nanospheres as novel titration reagents for anions. The nanospheres contain a lipophilic cation for which the counterion is initially Cl(-). Ion exchange takes place between Cl(-) in the nanospheres and a more lipophilic anion in the sample, such as ClO4(-) and NO3(-). Consecutive titration in the same sample solution for ClO4(-) and NO3(-) were demonstrated. As an application, the concentration of NO3(-) in spinach was successfully determined using this method.

  3. Determining gold in water by anion-exchange batch extraction

    USGS Publications Warehouse

    McHugh, J.B.

    1986-01-01

    This paper describes a batch procedure for determining gold in natural waters. It is completely adaptable to field operations. The water samples are filtered and acidified before they are equilibrated with an anion-exchange resin by shaking. The gold is then eluted with acetone-nitric acid solution, and the eluate evaporated to dryness. The residue is taken up in hydrobromic acid-bromine solution and the gold is extracted with methyl isobutyl ketone. The extract is electrothermally atomized in an atomic-absorption spectrophotometer. The limit of determination is 1 ng 1. ?? 1986.

  4. Regeneration of anion exchange resins by catalyzed electrochemical reduction

    DOEpatents

    Gu, Baohua; Brown, Gilbert M.

    2002-01-01

    Anion exchange resins sorbed with perchlorate may be regenerated by a combination of chemical reduction of perchlorate to chloride using a reducing agent and an electrochemical reduction of the oxidized reducing agent. Transitional metals including Ti, Re, and V are preferred chemical reagents for the reduction of perchlorate to chloride. Complexing agents such as oxalate are used to prevent the precipitation of the oxidized Ti(IV) species, and ethyl alcohol may be added to accelerate the reduction kinetics of perchlorate. The regeneration may be performed by continuously recycling the regenerating solution through the resin bed and an electrochemical cell so that the secondary waste generation is minimized.

  5. Trace adsorption of positively charged proteins onto Sepharose FF and Sepharose FF-based anion exchangers.

    PubMed

    Yu, Lin-Ling; Sun, Yan

    2012-08-31

    Agarose-based matrices have been widely used in ion exchange chromatography (IEC). We have herein observed that positively charged proteins (lysozyme and cytochrome c) are adsorbed on the agarose-based anion-exchangers (Q and DEAE Sepharose FF gels) in a capacity of 10-40 μg/mL. In contrast, negatively charged protein (bovine serum albumin) is not adsorbed to Sepharose FF and SP Sepharose FF gels. Elemental analysis of the gel indicated that the residual anionic sulfate groups in agarose would have worked as the cation exchange groups for the positively charged proteins. The trace adsorption behavior of lysozyme onto Sepharose FF and Sepharose FF-based anion exchangers was studied and the effects of NaCl concentration and cation group density on the adsorption were examined for better understanding of the trace adsorption in chromatographic processes. At NaCl concentrations less than 0.05 mol/L, which is the normal adsorption condition in IEC, the trace adsorption kept at a high level, so this trace adsorption cannot be avoided in the ionic strength range of routine IEC operations. Grafting poly(ethylenimine) (PEI) chain of 60 kDa to a cation group density of 700 mmol/L could reduce the adsorption capacity to about 20 μg/mL, but further reduction was not possible by increasing the cation group density to 1200 mmol/L. Therefore, attentions need to be paid to the phenomenon in protein purification practice using agarose-based matrices. The research is expected to call attentions to the trace adsorption on agarose-based matrices and to the importance in the selection of the suitable solid matrices in the production of high-purity protein products in large-scale bioprocesses.

  6. Bicarbonate-form anion exchange: affinity, regeneration, and stoichiometry.

    PubMed

    Rokicki, Christopher A; Boyer, Treavor H

    2011-01-01

    Magnetic ion exchange (MIEX) is an effective process for removing dissolved organic carbon (DOC) from natural waters, but its implementation has been limited due to production of waste sodium chloride solution (i.e., brine) from the regeneration process. Chloride is of concern because elevated concentrations can have adverse effects on engineered and natural systems. The goal of this research was to explore the efficacy of using anion exchange resin with bicarbonate as the mobile counter ion, which would produce a non-chloride regeneration solution. It was found that bicarbonate-form MIEX resin had a similar affinity as chloride-form MIEX resin for sulfate, nitrate, DOC, and ultraviolet-absorbing substances. Both bicarbonate-form and chloride-form MIEX resins showed the greatest removal efficiencies as fresh resin, and removal efficiency decreased with multiple regeneration cycles. Nevertheless, sodium bicarbonate solution was as effective as sodium chloride solution at regenerating MIEX resin. Regeneration of the bicarbonate-form MIEX resin was illustrated by sparging carbon dioxide gas in a water/resin slurry. This regeneration process would eliminate the need for the addition of salts such as sodium chloride or sodium bicarbonate. The stoichiometry of the bicarbonate-form resin revealed that the bicarbonate was deprotonating within the resin matrix leading to a mixture of both carbonate and bicarbonate mobile counter ions. This work makes an important contribution to ion exchange applications for water treatment by evaluating the affinity, regeneration, and stoichiometry of bicarbonate-form anion exchange.

  7. Synthesis of temperature-responsive anion exchanger via click reaction.

    PubMed

    Murakami, Kenji; Yu, Xue; Kato, Takahiro; Inoue, Yukihiko; Sugawara, Katsuyasu

    2012-06-15

    The temperature-responsive anion exchanger was synthesized by immobilizing the poly(N-isopropylacrylamide) (PNIPAM), a kind of the temperature-responsive polymer, on the external surface of mesoporous silica via click reaction. The structure of this synthesized composite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), elemental analysis, and nitrogen adsorption experiment. The amount of PNIPAM immobilized on the external surface of mesoporous silica, which was calculated from the weight loss measured by thermogravimetry, increased from 5.3 wt.% to 12.9 wt.% (dry) depending on the amount of PNIPAM added in the click reaction. The adsorption-desorption behavior of methyl orange (MO) ions in this synthesized anion exchanger was affected by the temperature of aqueous solution: the MO ions were adsorbed and desorbed reversibly and repeatedly with changing the pH of the solution at 25 °C, while the amount of adsorbed MO ions remained nearly constant at about 0.05 mmol/g independent of the pH of the solution at 40 °C. Also, the amount of PNIPAM immobilized on the mesoporous silica influenced the adsorption rate of MO ions, suggesting that the adsorption rate in this composite is controlled by the diffusion of MO ions through the PNIPAM layer.

  8. ANION EXCHANGE METHOD FOR SEPARATION OF METAL VALUES

    DOEpatents

    Hyde, E.K.; Raby, B.A.

    1959-02-10

    A method is described for selectively separating radium, bismuth, poloniums and lead values from a metallic mixture of thc same. The mixture is dissolved in aqueous hydrochloric acid and the acidity is adjusted to between 1 to 2M in hydrochloric acid to form the anionic polychloro complexes of polonium and bismuth. The solution is contacted with a first anion exchange resin such as strong base quaternary ammonia type to selectively absorb the polonium and bismuth leaving the radium and lead in the effluent. The effluent, after treatment in hydrochloric acid to increase the hydrochloric acid concentration to 6M is contacted with a second anion exchange iesin of the same type as the above to selectively adsorb the lead leaving the radium in the effluent. Radium is separately recovered from the effluent from the second exchange column. Lead is stripped from the loaded resin of the second column by treatment with 3M hydrochloric acid solution. The loaded resin of the first column is washed with 8M hydrochloric acid solution to recover bismuth and then treated with strong nitric acid solution to recover polonium.

  9. A Novel Methodology to Synthesize Highly Conductive Anion Exchange Membranes

    NASA Astrophysics Data System (ADS)

    He, Yubin; Pan, Jiefeng; Wu, Liang; Zhu, Yuan; Ge, Xiaolin; Ran, Jin; Yang, Zhengjin; Xu, Tongwen

    2015-08-01

    Alkaline polyelectrolyte fuel cell now receives growing attention as a promising candidate to serve as the next generation energy-generating device by enabling the use of non-precious metal catalysts (silver, cobalt, nickel et al.). However, the development and application of alkaline polyelectrolyte fuel cell is still blocked by the poor hydroxide conductivity of anion exchange membranes. In order to solve this problem, we demonstrate a methodology for the preparation of highly OH- conductive anion exchange polyelectrolytes with good alkaline tolerance and excellent dimensional stability. Polymer backbones were grafted with flexible aliphatic chains containing two or three quaternized ammonium groups. The highly flexible and hydrophilic multi-functionalized side chains prefer to aggregate together to facilitate the formation of well-defined hydrophilic-hydrophobic microphase separation, which is crucial for the superior OH- conductivity of 69 mS/cm at room temperature. Besides, the as-prepared AEMs also exhibit excellent alkaline tolerance as well as improved dimensional stability due to their carefully designed polymer architecture, which provide new directions to pursue high performance AEMs and are promising to serve as a candidate for fuel cell technology.

  10. Evaluation of a new, macroporous polyvinylpyridine resin for processing plutonium using nitrate anion exchange

    SciTech Connect

    Marsh, S.F.

    1989-04-01

    Anion exchange in nitric acid is the major aqueous process used to recover and purify plutonium from impure scrap materials. Most strong-base anion exchange resins incorporate a styrene-divinylbenzene copolymer. A newly available, macroporous anion exchange resin based on a copolymer of 1-methyl-4-vinylpyridine and divinylbenzene has been evaluated. Comparative data for Pu(IV) sorption kinetics and capacity are presented for this new resin and two other commonly used anion exchange resins. The new resin offers high capacity and rapid sorption kinetics for Pu(IV) from nitric acid, as well as greatly stability to chemical and radiolytic degradation. 8 refs., 14 figs.

  11. Alkaline direct alcohol fuel cells using an anion exchange membrane

    NASA Astrophysics Data System (ADS)

    Matsuoka, Koji; Iriyama, Yasutoshi; Abe, Takeshi; Matsuoka, Masao; Ogumi, Zempachi

    Alkaline direct alcohol fuel cells using an OH-form anion exchange membrane and polyhydric alcohols were studied. A high open circuit voltage of ca. 800 mV was obtained for a cell using Pt-Ru/C (anode) and Pt/C (cathode) at 323 K, which was about 100-200 mV higher than that for a DMFC using Nafion ®. The maximum power densities were in the order of ethylene glycol > glycerol > methanol > erythritol > xylitol. Silver catalysts were used as a cathode catalyst to fabricate alkaline fuel cells, since silver catalyst is almost inactive in the oxidation of polyhydric alcohols. Alkaline direct ethylene glycol fuel cells using silver as a cathode catalyst gave excellent performance because higher concentrations of fuel could be supplied to the anode.

  12. Hydrothermal carbonaceous sphere based stationary phase for anion exchange chromatography.

    PubMed

    Zhao, Qiming; Wu, Shuchao; Zhang, Peimin; Zhu, Yan

    2017-01-15

    Monodisperse carbonaceous spheres produced by the hydrothermal carbonization of sucrose were first applied as green stationary phase for ion chromatography after quaternization. Depending on the polycondensation of methylamine and 1,4-butanediol diglycidyl ether, polymer containing quaternary ammonium groups were facilely grafted onto the surfaces of hydrothermal carbonaceous spheres (HCSs). The quaternized HCSs with different number of polyelectrolyte layers were characterized by scanning electron microscopy, brunauer-emmett-teller, fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and elemental analysis. The measurements of breakthrough curves demonstrated that more layers of grafted polyelectrolyte resulted in higher anion exchange capacity of stationary phase. With good stability, common inorganic anions, monocarboxylic acids, polarizable anions and carbohydrates were effectively separated on the stationary phases, respectively. The high hydrophilicity of HCS surface afforded excellent peak symmetry for all analytes. Furthermore, high-capacity HCSs stationary phase was successfully applied to detect fluoride in tea samples.

  13. Dual transport properties of anion exchanger 1: the same transmembrane segment is involved in anion exchange and in a cation leak.

    PubMed

    Barneaud-Rocca, Damien; Borgese, Franck; Guizouarn, Hélène

    2011-03-18

    Previous results suggested that specific point mutations in human anion exchanger 1 (AE1) convert the electroneutral anion exchanger into a monovalent cation conductance. In the present study, the transport site for anion exchange and for the cation leak has been studied by cysteine scanning mutagenesis and sulfhydryl reagent chemistry. Moreover, the role of some highly conserved amino acids within members of the SLC4 family to which AE1 belongs has been assessed in AE1 transport properties. The results suggest that the same transport site within the AE1 spanning domain is involved in anion exchange or in cation transport. A functioning mechanism for this transport site is proposed according to transport properties of the different studied point mutations of AE1.

  14. Optimized anion exchange membranes for vanadium redox flow batteries.

    PubMed

    Chen, Dongyang; Hickner, Michael A; Agar, Ertan; Kumbur, E Caglan

    2013-08-14

    In order to understand the properties of low vanadium permeability anion exchange membranes for vanadium redox flow batteries (VRFBs), quaternary ammonium functionalized Radel (QA-Radel) membranes with three ion exchange capacities (IECs) from 1.7 to 2.4 mequiv g(-1) were synthesized and 55-60 μm thick membrane samples were evaluated for their transport properties and in-cell battery performance. The ionic conductivity and vanadium permeability of the membranes were investigated and correlated to the battery performance through measurements of Coulombic efficiency, voltage efficiency and energy efficiency in single cell tests, and capacity fade during cycling. Increasing the IEC of the QA-Radel membranes increased both the ionic conductivity and VO(2+) permeability. The 1.7 mequiv g(-1) IEC QA-Radel had the highest Coulombic efficiency and best cycling capacity maintenance in the VRFB, while the cell's voltage efficiency was limited by the membrane's low ionic conductivity. Increasing the IEC resulted in higher voltage efficiency for the 2.0 and 2.4 mequiv g(-1) samples, but the cells with these membranes displayed reduced Coulombic efficiency and faster capacity fade. The QA-Radel with an IEC of 2.0 mequiv g(-1) had the best balance of ionic conductivity and VO(2+) permeability, achieving a maximum power density of 218 mW cm(-2) which was higher than the maximum power density of a VRFB assembled with a Nafion N212 membrane in our system. While anion exchange membranes are under study for a variety of VRFB applications, this work demonstrates that the material parameters must be optimized to obtain the maximum cell performance.

  15. Ether cleavage-triggered degradation of benzyl alkylammonium cations for polyethersulfone anion exchange membranes.

    PubMed

    Miyanishi, Shoji; Yamaguchi, Takeo

    2016-04-28

    Anion exchange membranes are of increasing interest due to their applications in many electrochemical devices such as solid-state alkaline fuel cells. However, their practical applications remain limited compared to proton exchange membranes as they have been found to degrade in alkaline media. This degradation is believed to be derived from the instability of the anion exchange group under alkaline conditions. Consequently, much effort has been focused on the development of an anion exchange group that is stable in alkaline media, allowing for application in membranes. Herein, we analyze the detailed alkaline degradation mechanism of a generally applied anion exchange membrane, composed of quaternary ammonium-modified polyethersulfone, using several model compounds. We found that decomposition of the anion exchange group was not derived from the instability of the ionic group itself, as commonly believed; rather, ether cleavage triggered the degradation of the ionic group. The mechanism proposed herein indicates that improvement of the backbone stability is much more important than optimization of the anion exchange group in developing a durable anion exchange membrane. Furthermore, careful analysis is necessary to precisely evaluate the stability of the anion exchange group in the membrane.

  16. Hetero-Epitaxial Anion Exchange Yields Single-Crystalline Hollow Nanoparticles

    SciTech Connect

    Park, Jungwon; Zheng, Haimei; Jun, Young-wook; Alivisatos, A. Paul

    2009-08-26

    Anion exchange with S was performed on ZnO colloidal nanoparticles. The resulting hollow ZnS nanoparticles are crystal whose shape is dictated by the initial ZnO. Crystallographic and elemental analyses provide insight into the mechanism of the anion exchange.

  17. Polyethyleneimine precipitation versus anion exchange chromatography in fractionating recombinant beta-glucuronidase from transgenic tobacco extract.

    PubMed

    Holler, Chris; Vaughan, David; Zhang, Chenming

    2007-02-16

    Tobacco has been studied as a possible host for the production of recombinant proteins. In this report, recombinant beta-glucuronidase (rGUS) was used as a model protein to study the feasibility of using polyethyleneimine (PEI) precipitation to fractionate acidic recombinant proteins from transgenic tobacco. Results showed that rGUS was preferentially precipitated when the PEI dosage was beyond 200mg PEI/g total protein. At 700-800 mg PEI/g total protein, nearly 100% rGUS was precipitated with less than 40% native tobacco proteins co-precipitated. Approximately 85-90% of the rGUS activity could be recovered from the precipitation pellet for an enrichment ratio of 2.7-3.4. As a comparison, anion exchange chromatography (AEX) yielded similar results to PEI precipitation with 66-90% rGUS activity recovered and an enrichment ratio of 1.8-3.1. The rGUS was further purified by an additional hydrophobic interaction chromatographic (HIC) step after precipitation or AEX. Similar results in terms of rGUS activity recovered and enrichment were obtained. The major interfering protein at the end of all purification steps is most likely the Fraction 1 protein ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco). The presence of this protein is likely the cause for the varying and somewhat low enrichment ratios, but it may be later removed via a size-exclusion chromatography step. PEI precipitation offers the advantage of allowing significant sample concentration prior to subsequent purification techniques such as chromatography and is much less expensive than chromatographic methods as well. Through direct comparison, this study shows that PEI may be used as an initial fractionation step in replacement of AEX to facilitate the purification of acidic recombinant proteins from transgenic tobacco.

  18. The role of polymer nanolayer architecture on the separation performance of anion-exchange membrane adsorbers: I. Protein separations.

    PubMed

    Bhut, Bharat V; Weaver, Justin; Carter, Andrew R; Wickramasinghe, S Ranil; Husson, Scott M

    2011-11-01

    This contribution describes the preparation of strong anion-exchange membranes with higher protein binding capacities than the best commercial resins. Quaternary amine (Q-type) anion-exchange membranes were prepared by grafting polyelectrolyte nanolayers from the surfaces of macroporous membrane supports. A focus of this study was to better understand the role of polymer nanolayer architecture on protein binding. Membranes were prepared with different polymer chain graft densities using a newly developed surface-initiated polymerization protocol designed to provide uniform and variable chain spacing. Bovine serum albumin and immunoglobulin G were used to measure binding capacities of proteins with different size. Dynamic binding capacities of IgG were measured to evaluate the impact of polymer chain density on the accessibility of large size protein to binding sites within the polyelectrolyte nanolayer under flow conditions. The dynamic binding capacity of IgG increased nearly linearly with increasing polymer chain density, which suggests that the spacing between polymer chains is sufficient for IgG to access binding sites all along the grafted polymer chains. Furthermore, the high dynamic binding capacity of IgG (>130 mg/mL) was independent of linear flow velocity, which suggests that the mass transfer of IgG molecules to the binding sites occurs primarily via convection. Overall, this research provides clear evidence that the dynamic binding capacities of large biologics can be higher for well-designed macroporous membrane adsorbers than commercial membrane or resin ion-exchange products. Specifically, using controlled polymerization leads to anion-exchange membrane adsorbers with high binding capacities that are independent of flow rate, enabling high throughput. Results of this work should help to accelerate the broader implementation of membrane adsorbers in bioprocess purification steps.

  19. Preparation of a dibenzylated 1,4-diazacyclohexane-derived strong anion-exchange stationary phase.

    PubMed

    Ruan, Juxiang; Zuo, Xiongjun; Lang, Qiwei; Zeng, Zhijian; Li, Chao

    2013-07-05

    This paper reports the preparation of a novel, silica-based, strong anion-exchange stationary phase from a 1,4-diazacyclohexane derivative. To prepare the difunctional strong anion-exchange stationary phase, activated silica beads were first bonded with 3-chloropropyltriethoxysilane and then reacted with 1-methylpiperazine followed by benzyl chloride. The silica beads, the strong anion-exchange stationary phase and its precusors were instrumentally characterized. Aromatic acids were separated with non-aqueous anion-exchange chromatography. After elution with eluant prepared in mixed solvents of water and methanol, the resulting 1,4-diazacyclohexane-derived, difunctional, strong anion-exchange stationary phase exhibited good separation and selectivity for the aromatic acids investigated. The effects of eluant pH, eluant ion concentration and solvent composites on the separations were investigated. Organic acids with different substituents were eluted in order of decreasing dissociation coefficients, with no observable peak shape differences.

  20. Simultaneous determination of NH4+, NO2(-) and NO3(-) by ion-exclusion/anion-exchange chromatography on a strongly basic anion-exchange resin with basic eluent.

    PubMed

    Mori, Masanobu; Hironaga, Takahiro; Itabashi, Hideyuki; Nakatani, Nobutake; Kozaki, Daisuke; Tanaka, Kazuhiko

    2012-04-01

    Ion-exclusion/anion-exchange chromatography (IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH(-)-form with basic eluent has been developed. The separation mechanism is based on the ion-exclusion/penetration effect for cations and the anion-exchange effect for anions to anion-exchange resin phase. This system is useful for simultaneous separation and determination of ammonium ion (NH4+), nitrite ion (NO2(-)), and nitrate ion (NO3(-)) in water samples. The resolution of analyte ions can be manipulated by changing the concentration of base in eluent on a polystyrene-divinylbenzene based strongly basic anion-exchange resin column. In this study, several separation columns, which consisted of different particle sizes, different functional groups and different anion-exchange capacities, were compared. As the results, the separation column with the smaller anion-exchange capacity (TSKgel Super IC-Anion) showed well-resolved separation of cations and anions. In the optimization of the basic eluent, lithium hydroxide (LiOH) was used as the eluent and the optimal concentration was concluded to be 2 mmol/L, considering the resolution of analyte ions and the whole retention times. In the optimal conditions, the relative standard deviations of the peak areas and the retention times of NH4+, NO2(-), and NO3(-) ranged 1.28% - 3.57% and 0.54% - 1.55%, respectively. The limits of detection at signal-to-noise of 3 were 4.10 micromol/L for NH4+, 1.87 micromol/L for NO2(-) and 2.83 micromol/L for NO3(-).

  1. Ion-exchange equilibrium of N-acetyl-D-neuraminic acid on a strong anionic exchanger.

    PubMed

    Wu, Jinglan; Ke, Xu; Zhang, Xudong; Zhuang, Wei; Zhou, Jingwei; Ying, Hanjie

    2015-09-15

    N-acetyl-D-neuraminic acid (Neu5Ac) is a high value-added product widely applied in the food industry. A suitable equilibrium model is required for purification of Neu5Ac based on ion-exchange chromatography. Hence, the equilibrium uptake of Neu5Ac on a strong anion exchanger, AD-1 was investigated experimentally and theoretically. The uptake of Neu5Ac by the hydroxyl form of the resin occurred primarily by a stoichiometric exchange of Neu5Ac(-) and OH(-). The experimental data showed that the selectivity coefficient for the exchange of Neu5Ac(-) with OH(-) was a non-constant quantity. Subsequently, the Saunders' model, which took into account the dissociation reactions of Neu5Ac and the condition of electroneutrality, was used to correlate the Neu5Ac sorption isotherms at various solution pHs and Neu5Ac concentrations. The model provided an excellent fit to the binary exchange data for Cl(-)/OH(-) and Neu5Ac(-)/OH(-), and an approximate prediction of equilibrium in the ternary system Cl(-)/Neu5Ac(-)/OH(-). This basic information combined with the general mass transfer model could lay the foundation for the prediction of dynamic behavior of fixed bed separation process afterwards.

  2. Development of a modular virus clearance package for anion exchange chromatography operated in weak partitioning mode.

    PubMed

    Iskra, Timothy; Sacramo, Ashley; Gallo, Chris; Godavarti, Ranga; Chen, Shuang; Lute, Scott; Brorson, Kurt

    2015-01-01

    Anion exchange chromatography (AEX) operated under weak partitioning mode has been proven to be a powerful polishing step as well as a robust viral clearance step in Pfizer's monoclonal antibody (mAb) platform purification process. A multivariate design of experiment (DoE) study was conducted to understand the impact of operating parameters and feedstream impurity levels on viral clearance by weak partitioning mode AEX. Bacteriophage was used initially as a surrogate for neutral and acidic isoelectric point mammalian viruses (e.g., retrovirus and parvovirus). Five different mAbs were used in the evaluation of process parameters such as load challenge (both product and impurities), load pH, load conductivity, and contact time (bed height and flow-rate). The operating ranges obtained from phage clearance studies and Pfizer's historical data were used to define an appropriate operating range for a subsequent clearance study with model retrovirus and parvovirus. Both phage and virus clearance evaluations included feedstreams containing different levels of impurities such as high molecular mass species (HMMS), host cell proteins (HCPs), and host cell DNA. For all the conditions tested, over 5 log10 of clearance for both retrovirus and parvovirus was achieved. The results demonstrated that weak partitioning mode AEX chromatography is a robust step for viral clearance and has the potential to be included as part of the modular viral clearance approach.

  3. Modeling of protein-anion exchange resin interaction for the human growth hormone charge variants.

    PubMed

    Lapelosa, Mauro; Patapoff, Thomas W; Zarraga, Isidro E

    2015-12-01

    Modeling ion exchange chromatography (IEC) behavior has generated significant interest because of the wide use of IEC as an analytical technique as well as a preparative protein purification process; indeed there is a need for better understanding of what drives the unique behavior of protein charge variants. We hypothesize that a complex protein molecule, which contains both hydrophobic and charged moieties, would interact strongly with an in silico designed resin through charged electrostatic patches on the surface of the protein. In the present work, variants of recombinant human growth hormone that mimic naturally-occurring deamidation products were produced and characterized in silico. The study included these four variants: rhGH, N149D, N152D, and N149D/N152D. Poisson-Boltzmann calculations were used to determine surface electrostatic potential. Metropolis Monte Carlo simulations were carried out with the resulting variants to simulate IEC systems, examining the free energy of the interaction of the protein with an in silico anion exchange column represented by polylysine polypeptide. The results show that the charge variants have different average binding energies and the free energy of interaction can be used to predict the retention time for the different variants.

  4. Preparation of high purity egg phosvitin using anion exchange chromatography.

    PubMed

    Ren, Jiandong; Wu, Jianping

    2014-09-01

    Egg yolk phosvitin serves as a warehouse to provide metal ions for embryo development. It is significant for mineral metabolism study and also of great potential to be developed into functional foods with mineral absorption promoting ability. In this study, phosvitin was first extracted from yolk granules using 10% NaCl, dialysed and then adjusted to various pHs to remove impurities. The purity of phosvitin extracts was increased from 54.5% to 63.7% at decreasing pH from 8.0 to 5.5, and started to decrease afterwards. Both the yield and recovery were significantly decreased at decreasing pHs, especially at pHs close to its pI (pH 4.0), indicating the occurrence of co-precipitation of phosvitin with HDL. The extract prepared at pH 8.0 showed the highest recovery of 82.7%; its purity was increased from 54.5% to 97.1% by anion exchange chromatography, with a recovery of 42.0%. This simple method could be scaled up for industrial production.

  5. Effects of arginine on multimodal anion exchange chromatography.

    PubMed

    Hirano, Atsushi; Arakawa, Tsutomu; Kameda, Tomoshi

    2015-12-01

    The effects of arginine on binding and elution properties of a multimodal anion exchanger, Capto adhere, were examined using bovine serum albumin (BSA) and a monoclonal antibody against interleukin-8 (mAb-IL8). Negatively charged BSA was bound to the positively charged Capto adhere and was readily eluted from the column with a stepwise or gradient elution using 1M NaCl at pH 7.0. For heat-treated BSA, small oligomers and remaining monomers were also eluted using a NaCl gradient, whereas larger oligomers required arginine for effective elution. The positively charged mAb-IL8 was bound to Capto adhere at pH 7.0. Arginine was also more effective for elution of the bound mAb-IL8 than was NaCl. The results imply that arginine interacts with the positively charged Capto adhere. The mechanism underlying the interactions of arginine with Capto adhere was examined by calculating the binding free energy between an arginine molecule and a Capto adhere ligand in water through molecular dynamics simulations. The overall affinity of arginine for Capto adhere is attributed to the hydrophobic and π-π interactions between an arginine side chain and the aromatic moiety of the ligand as well as hydrogen bonding between arginine and the ligand hydroxyl group, which may account for the characteristics of protein elution using arginine.

  6. Improved immunoadsorption procedure with anion-exchange bacterial cell columns.

    PubMed

    McKinney, R M; Thacker, L; Wong, M C; Hebert, G A

    1978-01-01

    Bacterial cell columns for immunoadsorption were prepared with Streptococcus cells and triethylaminoethyl cellulose (Cellex-T) matrix material as a model system. Good column flow properties and satisfactory retention of the cells were obtained with ratios as high as 2 ml of packed cells/3 g dry weight of cellulose. Anion-exchange fractionation of whole serum by the Cellex-T was prevented by using 0.25 M NaCl in the developing buffer. Antibodies were adsorbed directly from whole serum and recovered in high yield by desorption at pH 2.3. Pre-exposing bacterial cells to formalin and washing them with acetone was necessary to ensure that they remained on the columns. One strain of Streptococcus salivarius (SS 908) was satisfactorily retained on a column only after cells were labeled with fluorescein isothiocyanate and washed with acetone. The means by which Cellex-T retains bacterial cells appears to be a combination of electronic attraction and physical entrapment.

  7. Hydroxide Solvation and Transport in Anion Exchange Membranes.

    PubMed

    Chen, Chen; Tse, Ying-Lung Steve; Lindberg, Gerrick E; Knight, Chris; Voth, Gregory A

    2016-01-27

    Understanding hydroxide solvation and transport in anion exchange membranes (AEMs) can provide important insight into the design principles of these new membranes. To accurately model hydroxide solvation and transport, we developed a new multiscale reactive molecular dynamics model for hydroxide in aqueous solution, which was then subsequently modified for an AEM material. With this model, we investigated the hydroxide solvation structure and transport mechanism in the membrane. We found that a relatively even separation of the rigid side chains produces a continuous overlapping region for hydroxide transport that is made up of the first hydration shell of the tethered cationic groups. Our results show that hydroxide has a significant preference for this overlapping region, transporting through it and between the AEM side chains with substantial contributions from both vehicular (standard diffusion) and Grotthuss (proton hopping) mechanisms. Comparison of the AEM with common proton exchange membranes (PEMs) showed that the excess charge is less delocalized in the AEM than the PEMs, which is correlated with a higher free energy barrier for proton transfer reactions. The vehicular mechanism also contributes considerably more than the Grotthuss mechanism for hydroxide transport in the AEM, while our previous studies of PEM systems showed a larger contribution from the Grotthuss mechanism than the vehicular mechanism for proton transport. The activation energy barrier for hydroxide diffusion in the AEM is greater than that for proton diffusion in PEMs, implying a more significant enhancement of ion transport in the AEM at elevated temperatures.

  8. Hydroxide Solvation and Transport in Anion Exchange Membranes

    SciTech Connect

    Chen, Chen; Tse, Ying-Lung Steve; Lindberg, Gerrick E.; Knight, Chris; Voth, Gregory A.

    2016-01-27

    Understanding hydroxide solvation and transport in anion exchange membranes (AEMs) can provide important insight into the design principles of these new membranes. To accurately model hydroxide solvation and transport, we developed a new multiscale reactive molecular dynamics model for hydroxide in aqueous solution, which was then subsequently modified for an AEM material. With this model, we investigated the hydroxide solvation structure and transport mechanism in the membrane. We found that a relatively even separation of the rigid side chains produces a continuous overlapping region for hydroxide transport that is made up of the first hydration shell of the tethered cationic groups. Our results show that hydroxide has a significant preference for this overlapping region, transporting through it and between the AEM side chains with substantial contributions from both vehicular (standard diffusion) and Grotthuss (proton hopping) mechanisms. Comparison of the AEM with common proton exchange membranes (PEMs) showed that the excess charge is less delocalized in the AEM than the PEMs, which is correlated with a higher free energy barrier for proton transfer reactions. The vehicular mechanism also contributes considerably more than the Grotthuss mechanism for hydroxide transport in the AEM, while our previous studies of PEM systems showed a larger contribution from the Grotthuss mechanism than the vehicular mechanism for proton transport. The activation energy barrier for hydroxide diffusion in the AEM is greater than that for proton diffusion in PEMs, implying a more significant enhancement of ion transport in the AEM at elevated temperatures.

  9. Anion-exchange resin-based desulfurization process

    SciTech Connect

    Sheth, A.C.; Strevel, S.D.; Dharmapurikar, R.

    1992-01-01

    Under the current grant, the University of Tennessee Space Institute (UTSI) will carry out the bench scale evaluation and further development of the anion-exchange resin-based desulfurization concept to desulfurize alkali metal sulfates. This concept has been developed and patented by UTSI under US Patent No. 4,917,874. The developmental program proposed under this DOE grant includes screening of commercially available resins to select three candidate resins for further study. These three resins will undergo a series of experiments designed to test the resins' performance under different process conditions (including the use of spent MHD seed material). The best of these resins will be used in optimizing the regeneration step and in testing the effects of performance enhancers. The process schematic developed from the results will be used to estimate the related economics. During this reporting period, October 1, 1991 to September 30, 1992, analysis of batch mode screening experiments was completed to select three candidate resins for process variables study in the fixed-bed set-up. This setup was modified and the experiments were carded out to evaluate effects of major process variables. The analysis of fixed-bed experiments is going on and we have also started simple batch mode experiments to identify desirable conditions for resin regeneration step. We have also started simple process engineering type calculations to determine the trade-off between the solution concentration and the resulting evaporation/concentration load.

  10. Fouling of an anion exchange chromatography operation in a monoclonal antibody process: Visualization and kinetic studies

    PubMed Central

    Close, Edward J; Salm, Jeffrey R; Iskra, Timothy; Sørensen, Eva; Bracewell, Daniel G

    2013-01-01

    Fouling of chromatographic resins over their operational lifetimes can be a significant problem for commercial bioseparations. In this article, scanning electron microscopy (SEM), batch uptake experiments, confocal laser scanning microscopy (CLSM) and small-scale column studies were applied to characterize a case study where fouling had been observed during process development. The fouling was found to occur on an anion exchange (AEX) polishing step following a protein A affinity capture step in a process for the purification of a monoclonal antibody. Fouled resin samples analyzed by SEM and batch uptake experiments indicated that after successive batch cycles, significant blockage of the pores at the resin surface occurred, thereby decreasing the protein uptake rate. Further studies were performed using CLSM to allow temporal and spatial measurements of protein adsorption within the resin, for clean, partially fouled and extensively fouled resin samples. These samples were packed within a miniaturized flowcell and challenged with fluorescently labeled albumin that enabled in situ measurements. The results indicated that the foulant has a significant impact on the kinetics of adsorption, severely decreasing the protein uptake rate, but only results in a minimal decrease in saturation capacity. The impact of the foulant on the kinetics of adsorption was further investigated by loading BSA onto fouled resin over an extended range of flow rates. By decreasing the flow rate during BSA loading, the capacity of the resin was recovered. These data support the hypothesis that the foulant is located on the particle surface, only penetrating the particle to a limited degree. The increased understanding into the nature of the fouling can help in the continued process development of this industrial example. Scanning electron microscopy (SEM), batch uptake experiments, confocal laser scanning microscopy (CLSM) and small-scale column experiments were applied to characterize a

  11. High-capacity anion exchangers based on poly (glycidylmethacrylate-divinylbenzene) microspheres for ion chromatography.

    PubMed

    Liu, Junwei; Wang, Yong; Cheng, Heli; Wang, Nani; Wu, Shuchao; Zhang, Peimin; Zhu, Yan

    2016-10-01

    Poly (glycidylmethacrylate-divinylbenzene) microspheres were prepared by the two-staged swelling and polymerization method and applied to prepare anion exchange stationary phases. Methylamine, dimethylamine, trimethylamine, diethylamine and triethylamine were selected to prepare the quaternary ammonium groups of anion exchangers, respectively. The diameters and surface characteristics of microspheres were measured by scanning electron microscope and nitrogen adsorption-desorption measurements. The anion exchangers were characterized by Fourier transform infrared spectrum, elemental analysis and breakthrough curve methods. The chromatographic performances of anion exchangers were illustrated by separating conventional anions, organic weak acids and carbohydrates. The results indicated that the anion exchange capacities were controllable by changing either the content of glycidylmethacrylate in microspheres or the number of bonded quaternary ammonium layer. Meanwhile, the substituents of quaternary ammonium groups greatly influenced the separation properties of anion exchangers. Finally, the three-layer methylamine-quaternized anion exchanger was successfully applied for the determination of fluoride in tea sample. The content of fluoride was detected to be 0.13mgg(-1) without the interference of acetate and formate.

  12. The Protein Maker: an automated system for high-throughput parallel purification

    PubMed Central

    Smith, Eric R.; Begley, Darren W.; Anderson, Vanessa; Raymond, Amy C.; Haffner, Taryn E.; Robinson, John I.; Edwards, Thomas E.; Duncan, Natalie; Gerdts, Cory J.; Mixon, Mark B.; Nollert, Peter; Staker, Bart L.; Stewart, Lance J.

    2011-01-01

    The Protein Maker is an automated purification system developed by Emerald BioSystems for high-throughput parallel purification of proteins and antibodies. This instrument allows multiple load, wash and elution buffers to be used in parallel along independent lines for up to 24 individual samples. To demonstrate its utility, its use in the purification of five recombinant PB2 C-terminal domains from various subtypes of the influenza A virus is described. Three of these constructs crystallized and one diffracted X-rays to sufficient resolution for structure determination and deposition in the Protein Data Bank. Methods for screening lysis buffers for a cytochrome P450 from a pathogenic fungus prior to upscaling expression and purification are also described. The Protein Maker has become a valuable asset within the Seattle Structural Genomics Center for Infectious Disease (SSGCID) and hence is a potentially valuable tool for a variety of high-throughput protein-purification applications. PMID:21904043

  13. Removal of Pu238 from Neptunium Solution by Anion Exchange

    SciTech Connect

    KYSER, EDWARD

    2003-12-01

    A new anion flowsheet for use in HB-Line was tested in the lab with Reillex{trademark} HPQ for removal of Pu{sup 238} contamination from Np. Significant rejection of Pu{sup 238} was observed by washing with 6 to 12 bed volumes (BV) of reductive wash containing reduced nitric acid concentration along with both ferrous sulfamate (FS) and hydrazine. A shortened-height column was utilized in these tests to match changes in the plant equipment. Lab experiments scaled to plant batch sizes of 1500 to 2200 g Np were observed with modest losses for up-flow washing. Down-flow washing was observed to have high losses. The following are recommended conditions for removing Pu{sup 238} from Np solutions by anion exchange in HB-Line: (1) Feed conditions: Up-flow 6.4-8 M HNO{sub 3}, 0.02 M hydrazine, 0.05 M excess FS, less than 5 days storage of solution after FS addition. (2) Reductive Wash conditions: Up-flow 6-12 BV of 6.4 M HNO{sub 3}, 0.05 M FS, 0.05 M hydrazine. 1.8 mL/min/cm{sup 2} flowrate. (3) Decontamination Wash conditions: Up-flow 1-2 BV of 6.4-8 M HNO{sub 3}, no FS, no hydrazine. (4) Elution conditions: Down-flow 0.17 M HNO{sub 3}, 0.05 M hydrazine, no FS.

  14. Anion exchanger 2 is essential for spermiogenesis in mice

    PubMed Central

    Medina, Juan F.; Recalde, Sergio; Prieto, Jesús; Lecanda, Jon; Sáez, Elena; Funk, Colin D.; Vecino, Paola; van Roon, Marian A.; Ottenhoff, Roelof; Bosma, Piter J.; Bakker, Conny T.; Elferink, Ronald P. J. Oude

    2003-01-01

    Na+-independent anion exchangers (AE) mediate electroneutral exchange of Cl- for \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{HCO}}_{3}^{-}\\end{equation*}\\end{document} ions across cell membranes, being involved in intracellular pH and cell volume regulation and in transepithelial hydroionic fluxes. Bicarbonate activation of adenylyl cyclase is known to be necessary for sperm motility and sperm capacitation, and a few studies have suggested a possible role of AE carriers in reproduction. Among the four AE genes identified in mammals thus far, only Ae2 (Slc4a2) has been determined to be expressed in the male reproductive system, especially in developing spermatozoa and in epididymal epithelium. Most AE genes drive alternative transcription, which in mouse Ae2 results in several Ae2 isoforms. Here, we generated mice carrying a targeted disruption of Ae2 that prevents the expression of the three AE2 isoforms (Ae2a, Ae2b1, and Ae2b2) normally found in mouse testes. Male Ae2-/- mice (but not female Ae2-/- mice) are infertile. Histopathological analysis of Ae2-/- testes shows an interruption of spermiogenesis, with only a few late spermatids and a complete absence of spermatozoa in the seminiferous tubules. The number of apoptotic bodies is increased in the seminiferous tubules and in the epididymis, which also shows squamous metaplasia of the epididymal epithelium. Our findings reveal an essential role of Ae2 in mouse spermiogenesis and stress the recently postulated involvement of bicarbonate in germ-cell differentiation through the bicarbonate-sensitive soluble-adenylyl-cyclase pathway. PMID:14673081

  15. Ionic resistance and permselectivity tradeoffs in anion exchange membranes.

    PubMed

    Geise, Geoffrey M; Hickner, Michael A; Logan, Bruce E

    2013-10-23

    Salinity gradient energy technologies, such as reverse electrodialysis (RED) and capacitive mixing based on Donnan potential (Capmix CDP), could help address the global need for noncarbon-based energy. Anion exchange membranes (AEMs) are a key component in these systems, and improved AEMs are needed in order to optimize and extend salinity gradient energy technologies. We measured ionic resistance and permselectivity properties of quaternary ammonium-functionalized AEMs based on poly(sulfone) and poly(phenylene oxide) polymer backbones and developed structure-property relationships between the transport properties and the water content and fixed charge concentration of the membranes. Ion transport and ion exclusion properties depend on the volume fraction of water in the polymer membrane, and the chemical nature of the polymer itself can influence fine-tuning of the transport properties to obtain membranes with other useful properties, such as chemical and dimensional stability. The ionic resistance of the AEMs considered in this study decreased by more than 3 orders of magnitude (i.e., from 3900 to 1.6 Ω m) and the permselectivity decreased by 6% (i.e., from 0.91 to 0.85) as the volume fraction of water in the polymer was varied by a factor of 3.8 (i.e., from 0.1 to 0.38). Water content was used to rationalize a tradeoff relationship between the permselectivity and ionic resistance of these AEMs whereby polymers with higher water content tend to have lower ionic resistance and lower permselectivity. The correlation of ion transport properties with water volume fraction and fixed charge concentration is discussed with emphasis on the importance of considering water volume fraction when interpreting ion transport data.

  16. 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.

  17. Controlled optical properties of water-soluble CdTe nanocrystals via anion exchange.

    PubMed

    Li, Jing; Jia, Jianguang; Lin, Yuan; Zhou, Xiaowen

    2016-02-01

    We report a study on anion exchange reaction of CdTe nanocrystals with S(2-) in aqueous solution under ambient condition. We found that the optical properties of CdTe nanocrystals can be well tuned by controlling the reaction conditions, in which the reaction temperature is crucially important. At low reaction temperature, the product nanocrystals showed blue-shifts in both absorption and PL spectra, while the photoluminescence quantum yield (PLQY) was significantly enhanced. When anion exchanges were carried out at higher reaction temperature, on the other hand, obvious red shifts in absorption and PL spectra accompanied by a fast increase followed by gradual decrease in PLQY were observed. On variation of S(2-) concentration, it was found that the overall kinetics of Te(2-) for S(2-) exchanges depends also on [S(2-)] when anion exchanges were performed at higher temperature. A possible mechanism for anion exchanges in CdTe NCs was proposed.

  18. A step-wise approach to define binding mechanisms of surrogate viral particles to multi-modal anion exchange resin in a single solute system.

    PubMed

    Brown, Matthew R; Johnson, Sarah A; Brorson, Kurt A; Lute, Scott C; Roush, David J

    2017-01-21

    Multi-modal anion exchange resins combine properties of both anion exchange and hydrophobic interaction chromatography for commercial protein polishing and may provide some viral clearance as well. From a regulatory viral clearance claim standpoint, it is unclear if multi-modal resins are truly orthogonal to either single-mode anion exchange or hydrophobic interaction columns. To answer this, a strategy of solute surface assays and High Throughput Screening of resin in concert with a scale-down model of large scale chromatography purification was employed to determine the predominant binding mechanisms of a panel of bacteriophage (i.e., PR772, PP7, and ϕX174) to multi-modal and single mode resins under various buffer conditions. The buffer conditions were restricted to buffer environments suggested by the manufacturer for the multi-modal resin. Each phage was examined for estimated net charge expression and relative hydrophobicity using chromatographic based methods. Overall, PP7 and PR772 bound to the multimodal resin via both anionic and hydrophobic moieties, while ϕX174 bound predominantly by the anionic moiety. Biotechnol. Bioeng. 2017;9999: 1-8. © 2017 Wiley Periodicals, Inc.

  19. CATALYTIC PROMOTION OF THE ADSORPTION OF VANADIUM ON AN ANIONIC EXCHANGE RESIN

    DOEpatents

    Bailes, R.H.; Ellis, D.A.

    1958-08-26

    An improvement in the process for the recovery of vanadium from acidic phosphatic solutions is presented. In this process the vanadium is first oxidized to the pentavaleat state, and is then separated by contacting such solutions with an anion exchange resin whereby adsorption of the complexed pentavalent vanadium is effected. The improvement lies in the fact that adsorp tion of the vanadium complex by the anion exchange resin is promoted and improved by providing fiuoride ions in solution to be contacted.

  20. Active yeast ribosome preparation using monolithic anion exchange chromatography.

    PubMed

    Munoz, Antonio M; Yourik, Paul; Rajagopal, Vaishnavi; Nanda, Jagpreet S; Lorsch, Jon R; Walker, Sarah E

    2017-02-01

    In vitro studies of translation provide critical mechanistic details, yet purification of large amounts of highly active eukaryotic ribosomes remains a challenge for biochemists and structural biologists. Here, we present an optimized method for preparation of highly active yeast ribosomes that could easily be adapted for purification of ribosomes from other species. The use of a nitrogen mill for cell lysis coupled with chromatographic purification of the ribosomes results in 10-fold-increased yield and less variability compared with the traditional approach, which relies on sedimentation through sucrose cushions. We demonstrate that these ribosomes are equivalent to those made using the traditional method in a host of in vitro assays, and that utilization of this new method will consistently produce high yields of active yeast ribosomes.

  1. Active yeast ribosome preparation using monolithic anion exchange chromatography

    PubMed Central

    Munoz, Antonio M.; Yourik, Paul; Rajagopal, Vaishnavi; Lorsch, Jon R.

    2017-01-01

    ABSTRACT In vitro studies of translation provide critical mechanistic details, yet purification of large amounts of highly active eukaryotic ribosomes remains a challenge for biochemists and structural biologists. Here, we present an optimized method for preparation of highly active yeast ribosomes that could easily be adapted for purification of ribosomes from other species. The use of a nitrogen mill for cell lysis coupled with chromatographic purification of the ribosomes results in 10-fold-increased yield and less variability compared with the traditional approach, which relies on sedimentation through sucrose cushions. We demonstrate that these ribosomes are equivalent to those made using the traditional method in a host of in vitro assays, and that utilization of this new method will consistently produce high yields of active yeast ribosomes. PMID:27981882

  2. Anion exchanger and the resistance against thermal haemolysis.

    PubMed

    Ivanov, I T; Zheleva, A; Zlatanov, I

    2011-01-01

    4,4'-Diiso-thiocyanato stilbene-2,2'-disulphonic acid (DIDS) is a membrane-impermeable, highly specific covalent inhibitor and powerful thermal stabiliser of the anion exchanger (AE1), the major integral protein of erythrocyte membrane (EM). Suspensions of control and DIDS-treated (15 µM, pH 8.2) human erythrocytes were heated from 20° to 70°C using various but constant heating rates (1-8°C/min). The cellular electrolyte leakage exhibited a sigmoidal response to temperature as detected by conductometry. The critical midpoint temperature of leakage, T(mo), extrapolated to low heating rate (0.5°C/min) was used as a measure for EM thermostability. T(mo) was greater for DIDS-treated erythrocytes, 63.2° ± 0.3°C, than for intact erythrocytes, 60.7° ± 0.2°C. The time, t(1/2), for 50% haemolysis of erythrocytes, exposed to 53°C was used as a measure for the resistance of erythrocytes against thermal haemolysis. The t(1/2) was also greater for DIDS-treated erythrocytes, 63 ± 3 min, than for intact erythrocytes, 38 ± 2 min. The fluorescent label N-(3-pyrenyl)maleimide and EPR spin label 3-maleimido-proxyl, covalently bound to sulphydryl groups of major EM proteins, were used to monitor the changes in molecular motions during transient heating. Both labels reported an intensification of the motional dynamics at the denaturation temperatures of spectrin (50°C) and AE1 (67°C), and, surprisingly, immobilisation of a major EM protein, presumably the AE1, at T(mo). The above results are interpreted in favour of the possible involvement of a predenaturational rearrangement of AE1 copies in the EM thermostability and the resistance against thermal haemolysis.

  3. Automated Purification of Recombinant Proteins: Combining High-throughput with High Yield

    SciTech Connect

    Lin, Chiann Tso; Moore, Priscilla A.; Auberry, Deanna L.; Landorf , Elizabeth V.; Peppler , Teresa; Victry, Kristin D.; Collart, Frank R.; Kery, Vladimir

    2006-05-01

    Protein crystallography, mapping protein interactions and other approaches of current functional genomics require not only purifying large numbers of proteins but also obtaining sufficient yield and homogeneity for downstream high-throughput applications. There is a need for the development of robust automated high-throughput protein expression and purification processes to meet these requirements. We developed and compared two alternative workflows for automated purification of recombinant proteins based on expression of bacterial genes in Escherichia coli: First - a filtration separation protocol based on expression of 800 ml E. coli cultures followed by filtration purification using Ni2+-NTATM Agarose (Qiagen). Second - a smaller scale magnetic separation method based on expression in 25 ml cultures of E.coli followed by 96-well purification on MagneHisTM Ni2+ Agarose (Promega). Both workflows provided comparable average yields of proteins about 8 ug of purified protein per unit of OD at 600 nm of bacterial culture. We discuss advantages and limitations of the automated workflows that can provide proteins more than 90 % pure in the range of 100 ug – 45 mg per purification run as well as strategies for optimization of these protocols.

  4. Strategies for developing design spaces for viral clearance by anion exchange chromatography during monoclonal antibody production.

    PubMed

    Strauss, Daniel M; Cano, Tony; Cai, Nick; Delucchi, Heather; Plancarte, Magdalena; Coleman, Daniel; Blank, Gregory S; Chen, Qi; Yang, Bin

    2010-01-01

    The quality-by-design (QbD) regulatory initiative promotes the development of process design spaces describing the multidimensional effects and interactions of process variables on critical quality attributes of therapeutic products. However, because of the complex nature of production processes, strategies must be devised to provide for design space development with reasonable allocation of resources while maintaining highly dependable results. Here, we discuss strategies for the determination of design spaces for viral clearance by anion exchange chromatography (AEX) during purification of monoclonal antibodies. We developed a risk assessment for AEX using a formalized method and applying previous knowledge of the effects of certain variables and the mechanism of action for virus removal by this process. We then use design-of-experiments (DOE) concepts to perform a highly fractionated factorial experiment and show that varying many process parameters simultaneously over wide ranges does not affect the ability of the AEX process to remove endogenous retrovirus-like particles from CHO-cell derived feedstocks. Finally, we performed a full factorial design and observed that a high degree of viral clearance was obtained for three different model viruses when the most significant process parameters were varied over ranges relevant to typical manufacturing processes. These experiments indicate the robust nature of viral clearance by the AEX process as well as the design space where removal of viral impurities and contaminants can be assured. In addition, the concepts and methodology presented here provides a general approach for the development of design spaces to assure that quality of biotherapeutic products is maintained.

  5. Structural and performance characteristics of representative anion exchange resins used for weak partitioning chromatography.

    PubMed

    Zhang, Shaojie; Iskra, Tim; Daniels, William; Salm, Jeffrey; Gallo, Christopher; Godavarti, Ranga; Carta, Giorgio

    2016-12-20

    Weak partitioning chromatography (WPC) has been proposed for the purification of monoclonal antibodies using an anion exchange (AEX) resin to simultaneously remove both acidic and basic protein impurities. Despite potential advantages, the relationship between resin structure and WPC performance has not been evaluated systematically. In this work, we determine the structure of representative AEX resins (Fractogel® EMD TMAE HiCap, Q Sepharose FF, and POROS 50 HQ) using transmission electron microscopy and inverse size exclusion chromatography and characterize protein interactions while operating these resins under WPC conditions using two mAb monomers, a mAb dimer, mAb multimers, and BSA as model products and impurities. We determine the isocratic elution behavior of the weakly bound monomer and dimer species and the adsorptive and mass transfer properties of the strongly bound multimers and BSA by confocal laser scanning microscopy. The results show that for each resin, using the product Kp value as guidance, salt, and pH conditions can be found where mAb multimers and BSA are simultaneously removed. Isocratic elution and adsorption mechanisms are, however, different for each resin and for the different components. Under WPC conditions, the Fractogel resin exhibited very slow diffusion of both mAb monomer and dimer species but fast adsorption for both mAb multimers and BSA with high capacity for BSA, while the Sepharose resin, because of its small pore size, was unable to effectively remove mAb multimers. The POROS resin was instead able to bind both multimers and BSA effectively, while exhibiting a greater resolution of mAb monomer and dimer species. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 2017.

  6. Acute and chronic influence of temperature on red blood cell anion exchange.

    PubMed

    Jensen, F B; Wang, T; Brahm, J

    2001-01-01

    Unidirectional (36)Cl(-) efflux via the red blood cell anion exchanger was measured under Cl(-) self-exchange conditions (i.e. no net flow of anions) in rainbow trout Oncorhynchus mykiss and red-eared freshwater turtle Trachemys scripta to examine the effects of acute temperature changes and acclimation temperature on this process. We also evaluated the possible adaptation of anion exchange to different temperature regimes by including our previously published data on other animals. An acute temperature increase caused a significant increase in the rate constant (k) for unidirectional Cl(-) efflux in rainbow trout and freshwater turtle. After 3 weeks of temperature acclimation, 5 degrees C-acclimated rainbow trout showed only marginally higher Cl(-) transport rates than 15 degrees C-acclimated trout when compared at the same temperature. Apparent activation energies for red blood cell Cl(-) exchange in trout and turtle were lower than values reported in endothermic animals. The Q(10) for red blood cell anion exchange was 2.0 in trout and 2.3 in turtle, values close to those for CO(2) excretion, suggesting that, in ectothermic animals, the temperature sensitivity of band-3-mediated anion exchange matches the temperature sensitivity of CO(2) transport (where red blood cell Cl(-)/HCO(3)(-) exchange is a rate-limiting step). In endotherms, such as man and chicken, Q(10) values for red blood cell anion exchange are considerably higher but are no obstacle to CO(2) transport, because body temperature is normally kept constant at values at which anion exchange rates are high. When compared at constant temperature, red blood cell Cl(-) permeability shows large differences among species (trout, carp, eel, cod, turtle, alligator, chicken and man). Cl(-) permeabilities are, however, remarkable similar when compared at preferred body temperatures, suggesting an appropriate evolutionary adaptation of red blood cell anion exchange function to the different thermal niches occupied

  7. Determination of cyanuric acid in milk powder by anion-exchange chromatography.

    PubMed

    Wang, Hui; Hou, Shengjie; Ding, Mingyu; Zhang, Jinghua

    2010-01-01

    An anion-exchange chromatographic method has been developed for simultaneous analysis of cyanuric acid (CA) and five inorganic anions (F(-), Cl(-), NO(3)(-), HPO(4)(2-) and SO(4)(2-)) in milk powder. The separation was achieved within 15 min on an anion-exchange column with simple elution of Na(2)CO(3)/NaHCO(3) buffer as mobile phase. Furthermore, the effect of the total concentration of Na(2)CO(3)/NaHCO(3) buffer on the retention of five inorganic anions was more obvious than that on CA retention, which indicated that CA retention on anion-exchange column depends not only on anion-exchange interaction but also on hydrophobic interactions between CA and anion-exchange column. The linear range of the calibration curve for CA was 0.1-100 mg L(-1). The detection limit calculated at S/N = 3 was 0.083 mg L(-1). The method was successfully applied to the analysis of CA in milk powder.

  8. Removal of dissolved organic matter by anion exchange: Effect of dissolved organic matter properties

    USGS Publications Warehouse

    Boyer, T.H.; Singer, P.C.; Aiken, G.R.

    2008-01-01

    Ten isolates of aquatic dissolved organic matter (DOM) were evaluated to determine the effect that chemical properties of the DOM, such as charge density, aromaticity, and molecular weight, have on DOM removal by anion exchange. The DOM isolates were characterized asterrestrial, microbial, or intermediate humic substances or transphilic acids. All anion exchange experiments were conducted using a magnetic ion exchange (MIEX) resin. The charge density of the DOM isolates, determined by direct potentiometric titration, was fundamental to quantifying the stoichiometry of the anion exchange mechanism. The results clearly show that all DOM isolates were removed by anion exchange; however, differences among the DOM isolates did influence their removal by MIEX resin. In particular, MIEX resin had the greatest affinity for DOM with high charge density and the least affinity for DOM with low charge density and low aromaticity. This work illustrates that the chemical characteristics of DOM and solution conditions must be considered when evaluating anion exchange treatment for the removal of DOM. ?? 2008 American Chemical Society.

  9. Automated genomic DNA purification options in agricultural applications using MagneSil paramagnetic particles

    NASA Astrophysics Data System (ADS)

    Bitner, Rex M.; Koller, Susan C.

    2002-06-01

    The automated high throughput purification of genomic DNA form plant materials can be performed using MagneSil paramagnetic particles on the Beckman-Coulter FX, BioMek 2000, and the Tecan Genesis robot. Similar automated methods are available for DNA purifications from animal blood. These methods eliminate organic extractions, lengthy incubations and cumbersome filter plates. The DNA is suitable for applications such as PCR and RAPD analysis. Methods are described for processing traditionally difficult samples such as those containing large amounts of polyphenolics or oils, while still maintaining a high level of DNA purity. The robotic protocols have ben optimized for agricultural applications such as marker assisted breeding, seed-quality testing, and SNP discovery and scoring. In addition to high yield purification of DNA from plant samples or animal blood, the use of Promega's DNA-IQ purification system is also described. This method allows for the purification of a narrow range of DNA regardless of the amount of additional DNA that is present in the initial sample. This simultaneous Isolation and Quantification of DNA allows the DNA to be used directly in applications such as PCR, SNP analysis, and RAPD, without the need for separate quantitation of the DNA.

  10. A simple halide-to-anion exchange method for heteroaromatic salts and ionic liquids.

    PubMed

    Alcalde, Ermitas; Dinarès, Immaculada; Ibáñez, Anna; Mesquida, Neus

    2012-04-02

    A broad and simple method permitted halide ions in quaternary heteroaromatic and ammonium salts to be exchanged for a variety of anions using an anion exchange resin (A(-) form) in non-aqueous media. The anion loading of the AER (OH(-) form) was examined using two different anion sources, acids or ammonium salts, and changing the polarity of the solvents. The AER (A(-) form) method in organic solvents was then applied to several quaternary heteroaromatic salts and ILs, and the anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Relying on the hydrophobicity of the targeted ion pair for the counteranion swap, organic solvents with variable polarity were used, such as CH(3)OH, CH(3)CN and the dipolar nonhydroxylic solvent mixture CH(3)CN:CH(2)Cl(2) (3:7) and the anion exchange was equally successful with both lipophilic cations and anions.

  11. Cr(VI) removal via anion exchange on a silver-triazolate MOF.

    PubMed

    Li, Li-Li; Feng, Xiao-Quan; Han, Run-Ping; Zang, Shuang-Quan; Yang, Guang

    2017-01-05

    Gram-scale synthesis of a silver-triazolato framework - {[Ag8(tz)6](NO3)2·6H2O}n (1-NO3; tz(-)=3,5-diphenyl-1,2,4-triazolate) - has been achieved, enabling the systematic investigation of its anion-exchange properties. Our experimental results show that the anion-exchange pattern of 1-NO3 conforms to the so-called Hofmeister bias, which has been correlated to the hydrophobic nature of the MOF pores, and can be understood by considering the difference between the hydration energies of the exchanging anions. Furthermore, 1-NO3 displays a fast, efficient, and reversible adsorption of HCrO4(-) (via anion-exchange) from Cr(VI)-containing aqueous solution (Qmax=37.0 Cr mg/g, 303K), rendering it a promising prototype of a recyclable MOF for Cr(VI) removal.

  12. Quaternized poly (styrene-co-vinylbenzyl chloride) anion exchange membranes for alkaline water electrolysers

    NASA Astrophysics Data System (ADS)

    Vengatesan, S.; Santhi, S.; Jeevanantham, S.; Sozhan, G.

    2015-06-01

    In this study, poly (ST-co-VBC) based anion exchange membranes with different styrene to VBC ratios (1: 0.16, 1: 0.33 and 1: 1) have been prepared via chloromethylation-free synthetic route using aromatic vinyl monomers. The synthesized co-polymers are identified by FTIR and 1H-NMR analysis. Hydroxide (OH-) ion conductivity of the anion exchange membrane with styrene to VBC ratio of 1: 0.33 is as high as 6.8 × 10-3 S cm-1 in de-ionised water at 25 °C. The membrane also acquires the ion-exchange capacity of 2.14 meq. g-1, and the water uptake of 127%. Membrane-electrode-assembly (MEA) using the anion exchange membrane and Ni - foam catalyst demonstrate the current density of 40 mA cm-2 at 2.3 V in a water electrolyser cell.

  13. Measurement of the distribution of anion exchange function in normal human red cells.

    PubMed Central

    Raftos, J E; Bookchin, R M; Lew, V L

    1997-01-01

    1. The aim of the present work was to investigate cell-to-cell variation in anion exchange turnover in normal human red cells. Red cells permeabilized to protons and K+ dehydrate extremely rapidly by processes that are rate-limited by the induced K+ permeability or by anion exchange turnover. Conditions were designed to render dehydration rate-limited by anion exchange turnover. Cell-to-cell variation in anion exchange function could then be measured from the distribution of delay times required for dehydrating cells to attain resistance to haemolysis in a selected hypotonic medium. 2. Red cells were suspended at 10% haematocrit in a low-K+ solution and, after a brief preincubation with 20 microM SITS at 4 degrees C, were warmed to 24 degrees C, and the protonophore CCCP was added (20 microM) followed 2 min later by valinomycin (60 microM). Delay times for cells to become resistant to lysis were measured from the instant of valinomycin addition by sampling suspension aliquots into thirty volumes of 35 mM NaCl. After centrifugation the per cent lysis was estimated by measuring the haemoglobin concentration in the supernatant. Typical median delay times with this standardized method were 4-5 min. 3. The statistical parameters of the delay time distributions report the population spread in the transport function that was limiting to dehydration. In the absence of SITS and CCCP, dehydration was limited by the diffusional Cl- permeability (PCl). Delay time distributions for PCl- and anion exchange-limited dehydration were measured in red cells from three normal donors. For both distributions, the coefficients of variation ranged between 13.0 and 15.2%, indicating a high degree of uniformity in PCl and anion exchange function among individual red cells. PMID:9061637

  14. Nitrosamine, dimethylnitramine, and chloropicrin formation during strong base anion-exchange treatment.

    PubMed

    Kemper, Jerome M; Westerhoff, Paul; Dotson, Aaron; Mitch, William A

    2009-01-15

    Strong base anion-exchange resins represent an important option for water utilities and homeowners to address growing concerns with nitrate, arsenate, and perchlorate contamination of source waters. Most commercially available anion-exchange resins employ quaternary amine functional groups. Previous research has provided contradictory evidence regarding whether these resins serve as sources of nitrosamines, considered as highly carcinogenic nitrogenous disinfection byproducts (N-DBPs), even without disinfectants. For three common varieties of commercial anion-exchange resins, we evaluated the importance of releases of nitrosamines, and two other N-DBPs (dimethylnitramine and chloropicrin), when the resins were subjected to typical column flow conditions with and without free chlorine or chloramine application upstream or downstream of the columns. In the absence of disinfectants, fresh trimethylamine- and tributylamine-based type 1 and dimethylethanolamine-based type 2 anion-exchange resins usually released 2-10 ng/L nitrosamines, likely due to shedding of manufacturing impurities, with excursions of up to 20 ng/L following regeneration. However, the lack of significant nitrosamine release in a full-scale anion-exchange treatment system after multiple regeneration cycles indicates that releases may eventually subside. Resins also shed organic precursors that might contribute to nitrosamine formation within distribution systems when chloramines are applied downstream. With free chlorine or chloramine application upstream, nitrosamine concentrations were more significant, at 20-100 ng/L for the type 1 resins and approximately 400 ng/L for the type 2 resin. However, chloropicrin formation was lowest for the type 2 resin. Dimethylnitramine formation was significant with free chlorine application upstream but negligible with chloramines. Although no N-DBPs were detected in cation-exchange-based consumer point-of-use devices exposed to chlorinated or chloraminated waters

  15. Semi-automated protocol for purification of Mycobacterium leprae from tissues using the gentleMACS™ Octo Dissociator

    PubMed Central

    Williams, Diana L.; Adams, Linda B.; Lahiri, Ramanuj

    2014-01-01

    Mycobacterium leprae, etiologic agent of leprosy, is propagated in athymic nude mouse footpads (FPs). The current purification protocol is tedious and physically demanding. A simpler, semi-automated protocol was developed using gentleMACS™ Octo Dissociator. The gentleMACS protocol provided a very effective means for purification of highly viable M. leprae from tissue. PMID:25019518

  16. Semi-automated protocol for purification of Mycobacterium leprae from tissues using the gentleMACS™ Octo Dissociator.

    PubMed

    Williams, Diana L; Adams, Linda B; Lahiri, Ramanuj

    2014-10-01

    Mycobacterium leprae, etiologic agent of leprosy, is propagated in athymic nude mouse footpads (FPs). The current purification protocol is tedious and physically demanding. A simpler, semi-automated protocol was developed using gentleMACS™ Octo Dissociator. The gentleMACS protocol provided a very effective means for purification of highly viable M. leprae from tissue.

  17. Radiation stability of anion-exchange resins based on epichlorohydrin and vinylpyridines

    SciTech Connect

    Zainutdinov, S.S.; Dzhalilov, A.T.; Askarov, M.A.

    1983-02-01

    The vigorous development of nuclear technology and atomic energy and the hydrometallurgy of the rare and radioactive metals has made it necessary to create and use ion-exchange materials possessing a high resistance to the action of ionizing radiations and the temperature. In view of this, the necessity has arisen for obtaining ion-exchange materials possessing adequate radiation stability. The results of an investigation of the radiation stability of anion-exchange resins based on the products of spontaneous polymerization in the interaction of epichlorohydrin with vinylpyridines show that they possess higher radiation resistance than the industrial anion-exchange resin AN-31 used at the present time.

  18. Development of (126)Sn separation method by means of anion exchange resin and gamma spectroscopy.

    PubMed

    Dulanská, Silvia; Remenec, Boris; Bilohuščin, Ján; Mátel, Ľubomír; Bujdoš, Marek

    2017-05-01

    This paper describes a method employing anion exchange resin for determination of (126)Sn in radioactive waste. The method is suitable for the separation of (126)Sn isotope from hydrochloric and hydrofluoric acid solution. The separation is based on precipitation of tin with ammonium sulfide in 0.5molL(-1) HCl, dissolution of the precipitate in concentrated HCl, loading in 2molL(-1) HCl onto anion exchange resin column and elution with 2molL(-1) HNO3. (126)Sn was measured by gamma spectrometry.

  19. Separation of thorium and uranium in nitric acid solution using silica based anion exchange resin.

    PubMed

    Chen, Yanliang; Wei, Yuezhou; He, Linfeng; Tang, Fangdong

    2016-09-30

    To separate thorium and uranium in nitric acid solution using anion exchange process, a strong base silica-based anion exchange resin (SiPyR-N4) was synthesized. Batch experiments were conducted and the separation factor of thorium and uranium in 9M nitric acid was about 10. Ion exchange chromatography was applied to separate thorium and uranium in different ratios. Uranium could be eluted by 9M nitric acid and thorium was eluted by 0.1M nitric acid. It was proved that thorium and uranium can be separated and recovered successfully by this method.

  20. Generator breakthrough and radionuclidic purification in automated synthesis of 68Ga-DOTANOC.

    PubMed

    Belosi, Francesca; Cicoria, Gianfranco; Lodi, Filippo; Malizia, Claudio; Fanti, Stefano; Boschi, Stefano; Marengo, Mario

    2013-06-06

    68Ga labeled radiopharmaceuticals, like 68Ga-DOATNOC and other similar peptides, are gaining relevance in PET-CT, thanks to relatively easy local generator production, that do not requires an installed cyclotron. However, generator produced 68Ga is typically of suboptimal purity, mainly due to the breakthrough of the parent radionuclide 68Ge. Modern automated synthesis modules adopt both fractionation methods and purification methods in order to get rid of 68Ge breakthrough. Purification methods are mainly based on based on cationic prepurification even if anionic purification has been adopted as well. This work studies the efficacy of cationic prepurification using commercial STRATA-X-C, as well as distribution of the 68Ge contaminant during all steps of the synthesis of labeled peptides. Generator waste, STRATA-X-C purification cartridge, synthesis waste and the final product are quantitatively analyzed by means of high resolution gamma ray spectrometry. Our results show that current method of purification is highly effective; initial 68Ge breakthrough of the order of 1 kBq is decreased by a factor greater than 100, with removal of about 61% of the contaminant 68Ge in the first purification passage; this allow an efficient labeling, since removal of the remaining impurity happens during chelation in the reactor vessel. In conclusion, the synthesis with modular automated system resulted to reliably produce 68Ga-DOTANOC, with limited if any user intervention. 68Ge content in the final formulation results lower than 2x10(-7)%, avoiding unjustified patient irradiation due to radionuclidic impurities and satisfying quality prerequisites for radiopharmaceutical preparations.

  1. Anion-exchange synthesis of nanoporous FeP nanosheets as electrocatalysts for hydrogen evolution reaction.

    PubMed

    Xu, You; Wu, Rui; Zhang, Jingfang; Shi, Yanmei; Zhang, Bin

    2013-07-28

    Nanoporous FeP nanosheets are successfully synthesized via the anion-exchange reaction of inorganic-organic hybrid Fe18S25-TETAH (TETAH = protonated triethylenetetramine) nanosheets with P ions. The as-prepared nanoporous FeP nanosheets exhibit high electrochemical hydrogen evolution reaction activity in acidic medium.

  2. Separation of the rare earths by anion-exchange in the presence of lactic acid

    NASA Technical Reports Server (NTRS)

    Faris, J. P.

    1969-01-01

    Investigation of adsorption of rare earths and a few other elements to an anion-exchange resin from mixed solvents containing lactic acid shows that the lanthanides are absorbed more strongly than from the alpha-hydroxyisobutryric acid system, but with less separation between adjacent members of the series.

  3. OXIDATIVE STRESS ACTIVATES ANION EXCHANGE PROTEIN 2 AND AP-1 IN AIRWAY EPITHELIAL CELLS

    EPA Science Inventory

    Anion exchange protein 2 (AE2) is a membrane-bound protein that mediates chloride-bicarbonate exchange. In addition to regulating intracellular pH and cell volume, AE2 exports superoxide (O.) to the extracellular matrix in an HCO-dependent process. Given this ability to export O....

  4. Anion exchange resins as a source of nitrosamines and nitrosamine precursors.

    PubMed

    Flowers, Riley C; Singer, Philip C

    2013-07-02

    Anion exchange resins are important tools for the removal of harmful anionic contaminants from drinking water, but their use has been linked to the presence of carcinogenic nitrosamines in treated drinking water. In bench-scale batch and column experiments, anion exchange resins from a large, representative group were investigated as sources of the nitrosamines N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), and N-nitrosodi-n-butylamine (NDBA) and their precursors. Several resins were found to release high levels (up to >2000 ng/L, orders of magnitude above drinking water regulatory levels) of nitrosamines upon initial rinsing with lab-grade water, with levels subsiding within 50-100 bed volumes of rinsing. Resins released similarly high levels of nitrosamine precursors, with spikes in precursor release triggered by regeneration of resins with sodium chloride or by interruptions in flow resulting in prolonged contact times. Free chlorine or preformed monochloramine in feedwater led to the production of nitrosamines. Resins released different nitrosamines and precursors depending on their functional groups, with some resins releasing as many as three different nitrosamines and their precursors. These findings have significant implications for the pretreatment and appropriate use of anion exchange resins by drinking water utilities and for the production of anion exchange resins by manufacturers.

  5. DEMINERALIZER BUILDING, TRA608. CATION AND ANION EXCHANGERS LINE UP ALONG ...

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

    DEMINERALIZER BUILDING, TRA-608. CATION AND ANION EXCHANGERS LINE UP ALONG NORTH WALL ON CONCRETE PLATFORMS. INL NEGATIVE NO. 2527. Unknown Photographer, 6/12/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  6. Comparison of automated and manual purification of total RNA for mRNA-based identification of body fluids.

    PubMed

    Akutsu, Tomoko; Kitayama, Tetsushi; Watanabe, Ken; Sakurada, Koichi

    2015-01-01

    Silica column-based RNA purification procedures have widespread use in mRNA profiling for body fluid identification in forensic samples. Also, automated RNA purification systems employing magnetic bead technology have recently become available. In this preliminary study, to ascertain which RNA purification technology is more suitable for the identification of body fluids by real-time reverse transcription polymerase chain reaction (RT-PCR), comparative analyses of the yield and quality of total RNA were performed between automated purification using an EZ1 Advanced Instrument and manual purification using an RNeasy Mini Kit. The yield and size distribution of total RNA were compared by gene expression analysis of two different sized fragments of the β-actin gene. In addition, the relative amounts of several target genes were compared between the purification methods, and the integrity of total RNA was determined by chip-based electrophoresis. The results of this study suggest that RNeasy can purify higher-quality RNA as compared with automated purification using EZ1. The sensitivity of the RT-PCR analysis, however, was higher in the EZ1-purified samples, likely due to the relative efficiency of EZ1 in extracting short-length RNA from degraded samples. We also show that the quantification of relative levels of body fluid-specific genes could be influenced by the purification procedure. Our results indicate that although use of high-quality RNA is generally required for reproducible results in gene expression analysis, the forensic relevance of short RNA fragments in highly degraded samples cannot be ruled out. Furthermore, our results suggest that automated purification procedures as well as silica column-based manual purification procedures can be used for mRNA-based body fluid identification in forensic samples.

  7. Automated centrifugal-microfluidic platform for DNA purification using laser burst valve and coriolis effect.

    PubMed

    Choi, Min-Seong; Yoo, Jae-Chern

    2015-04-01

    We report a fully automated DNA purification platform with a micropored membrane in the channel utilizing centrifugal microfluidics on a lab-on-a-disc (LOD). The microfluidic flow in the LOD, into which the reagents are injected for DNA purification, is controlled by a single motor and laser burst valve. The sample and reagents pass successively through the micropored membrane in the channel when each laser burst valve is opened. The Coriolis effect is used by rotating the LOD bi-directionally to increase the purity of the DNA, thereby preventing the mixing of the waste and elution solutions. The total process from the lysed sample injection into the LOD to obtaining the purified DNA was finished within 7 min with only one manual step. The experimental result for Salmonella shows that the proposed microfluidic platform is comparable to the existing devices in terms of the purity and yield of DNA.

  8. Role of urea on recombinant Apo A-I stability and its utilization in anion exchange chromatography.

    PubMed

    Angarita, Monica; Arosio, Paolo; Müller-Späth, Thomas; Baur, Daniel; Falkenstein, Roberto; Kuhne, Wolfgang; Morbidelli, Massimo

    2014-08-08

    Apolipoprotein A-I (Apo A-I) is an important lipid-binding protein involved in the transport and metabolism of cholesterol. High protein purity, in particular with respect to endotoxins is required for therapeutic applications. The use of urea during the purification process of recombinant Apo A-I produced in Escherichia coli has been suggested so as to provide high endotoxin clearance. In this work, we show that urea can be used as a sole modifier during the ion exchange chromatographic purification of Apo A-I and we investigate the molecular mechanism of elution by correlating the effect of urea on self-association, conformation and adsorption equilibrium properties of a modified model Apo A-I. In the absence of urea the protein was found to be present as a population of oligomers represented mainly by trimers, hexamers and nonamers. The addition of urea induced oligomer dissociation and protein structure unfolding. We correlated the changes in protein association and conformation with variations of the adsorption equilibrium of the protein on a strong anion exchanger. It was confirmed that the adsorption isotherms, described by a Langmuir model, were dependent on both protein and urea concentrations. Monomers, observed at low urea concentration (0.5M), were characterized by larger binding affinity and adsorption capacity compared to both protein oligomers (0M) and unfolded monomers (2-8M). The reduction of both the binding strength and maximum adsorption capacity at urea concentrations larger than 0.5M explains the ability of urea of inducing elution of the protein from the ion exchange resin. The dissociation of the protein complexes occurring during the elution could likely be the origin of the effective clearance of endotoxins originally trapped inside the oligomers.

  9. Anion-Exchange Properties of Trifluoroacetate and Triflate Salts of N-Alkylammonium Resorcinarenes.

    PubMed

    Pan, Fangfang; Beyeh, Ngong Kodiah; Bertella, Stefania; Rissanen, Kari

    2016-03-04

    The synthesis of N-benzyl- and N-cyclohexylammonium resorcinarene trifluoroacetate (TFA) and triflate (OTf) salt receptors was investigated. Solid-state analysis by single-crystal X-ray diffraction revealed that the N-alkylammonium resorcinarene salts (NARSs) with different upper substituents had different cavity sizes and different affinities for anions. Anion-exchange experiments by mixing equimolar amounts of N-benzylammonium resorcinarene trifluoroacetate and N-cyclohexylammonium resorcinarene triflate, as well as N-benzylammonium resorcinarene triflate and N-cyclohexylammonium resorcinarene trifluoroacetate showed that the NARS with flexible benzyl groups preferred the larger OTf anion, whereas the rigid cyclohexyl groups preferred the smaller TFA anions. The anion-exchange processes were confirmed in the solid state by single-crystal and powder X-ray diffraction experiments and in the gas phase by electrospray ionization mass spectrometry.

  10. Mechanism of Polysulfone-Based Anion Exchange Membranes Degradation in Vanadium Flow Battery.

    PubMed

    Yuan, Zhizhang; Li, Xianfeng; Zhao, Yuyue; Zhang, Huamin

    2015-09-02

    The stability of hydrocarbon ion exchange membranes is one of the critical issues for a flow battery. However, the degradation mechanism of ion exchange membranes has been rarely investigated especially for anion exchange membranes. Here, the degradation mechanism of polysulfone based anion exchange membranes, carrying pyridine ion exchange groups, under vanadium flow battery (VFB) medium was investigated in detail. We find that sp(2) hybrid orbital interactions between pyridinic-nitrogen in 4,4'-bipyridine and benzylic carbon disrupt the charge state balance of pristine chloromethylated polysulfone. This difference in electronegativity inversely induces an electrophilic carbon center in the benzene ring, which can be attacked by the lone pair electron on the vanadium(V) oxygen species, further leading to the degradation of polymer backbone, while leaving the 4,4'-bipyridine ion exchange groups stable. This work represents a step toward design and construction of alternative type of chemically stable hydrocarbon ion exchange membranes for VFB.

  11. Crystal structure of the anion exchanger domain of human erythrocyte band 3.

    PubMed

    Arakawa, Takatoshi; Kobayashi-Yurugi, Takami; Alguel, Yilmaz; Iwanari, Hiroko; Hatae, Hinako; Iwata, Momi; Abe, Yoshito; Hino, Tomoya; Ikeda-Suno, Chiyo; Kuma, Hiroyuki; Kang, Dongchon; Murata, Takeshi; Hamakubo, Takao; Cameron, Alexander D; Kobayashi, Takuya; Hamasaki, Naotaka; Iwata, So

    2015-11-06

    Anion exchanger 1 (AE1), also known as band 3 or SLC4A1, plays a key role in the removal of carbon dioxide from tissues by facilitating the exchange of chloride and bicarbonate across the plasma membrane of erythrocytes. An isoform of AE1 is also present in the kidney. Specific mutations in human AE1 cause several types of hereditary hemolytic anemias and/or distal renal tubular acidosis. Here we report the crystal structure of the band 3 anion exchanger domain (AE1(CTD)) at 3.5 angstroms. The structure is locked in an outward-facing open conformation by an inhibitor. Comparing this structure with a substrate-bound structure of the uracil transporter UraA in an inward-facing conformation allowed us to identify the anion-binding position in the AE1(CTD), and to propose a possible transport mechanism that could explain why selected mutations lead to disease.

  12. Tuning the Optical Properties of Cesium Lead Halide Perovskite Nanocrystals by Anion Exchange Reactions

    PubMed Central

    2015-01-01

    We demonstrate that, via controlled anion exchange reactions using a range of different halide precursors, we can finely tune the chemical composition and the optical properties of presynthesized colloidal cesium lead halide perovskite nanocrystals (NCs), from green emitting CsPbBr3 to bright emitters in any other region of the visible spectrum, and back, by displacement of Cl– or I– ions and reinsertion of Br– ions. This approach gives access to perovskite semiconductor NCs with both structural and optical qualities comparable to those of directly synthesized NCs. We also show that anion exchange is a dynamic process that takes place in solution between NCs. Therefore, by mixing solutions containing perovskite NCs emitting in different spectral ranges (due to different halide compositions) their mutual fast exchange dynamics leads to homogenization in their composition, resulting in NCs emitting in a narrow spectral region that is intermediate between those of the parent nanoparticles. PMID:26214734

  13. Tuning the Optical Properties of Cesium Lead Halide Perovskite Nanocrystals by Anion Exchange Reactions.

    PubMed

    Akkerman, Quinten A; D'Innocenzo, Valerio; Accornero, Sara; Scarpellini, Alice; Petrozza, Annamaria; Prato, Mirko; Manna, Liberato

    2015-08-19

    We demonstrate that, via controlled anion exchange reactions using a range of different halide precursors, we can finely tune the chemical composition and the optical properties of presynthesized colloidal cesium lead halide perovskite nanocrystals (NCs), from green emitting CsPbBr3 to bright emitters in any other region of the visible spectrum, and back, by displacement of Cl(-) or I(-) ions and reinsertion of Br(-) ions. This approach gives access to perovskite semiconductor NCs with both structural and optical qualities comparable to those of directly synthesized NCs. We also show that anion exchange is a dynamic process that takes place in solution between NCs. Therefore, by mixing solutions containing perovskite NCs emitting in different spectral ranges (due to different halide compositions) their mutual fast exchange dynamics leads to homogenization in their composition, resulting in NCs emitting in a narrow spectral region that is intermediate between those of the parent nanoparticles.

  14. Facile surface modification of anion-exchange membranes for improvement of diffusion dialysis performance.

    PubMed

    Kim, Do-Hyeong; Park, Han-Sol; Seo, Seok-Jun; Park, Jin-Soo; Moon, Seung-Hyeon; Choi, Young-Woo; Jiong, Young Su; Kim, Dong Hee; Kang, Moon-Sung

    2014-02-15

    In this study, a facile membrane modification method by spin-coating of pyrrole (Py) monomers dissolved in a volatile solvent followed by an interfacial polymerization is proposed. The surface of a commercial anion-exchange membrane (i.e., Neosepta-AFX, Astom Corp., Japan) was successfully modified with polypyrrole (Ppy) to improve the acid recovery performance in diffusion dialysis (DD). The result of DD experiments revealed that both the acid and metal ion transports are significantly influenced by the surface modification. The metal crossover through the membranes was largely reduced while mostly maintaining the acid permeability by introducing a thin Ppy layer with excellent repelling property to cations on the membrane surface. As a result, the anion-exchange membrane modified with the optimum content of Py monomer (5 vol.%) exhibited excellent acid dialysis coefficient (KAcid) and selectivity (KAcid/KMetal) which is approximately twice as high as that of the pristine membrane.

  15. Radioactive iodine waste treatment using electrodialysis with an anion exchange paper membrane.

    PubMed

    Inoue, Hiroyoshi; Kagoshima, Mayumi; Yamasaki, Mariko; Honda, Yoko

    2004-12-01

    In order to simply and safely treat radioactive iodine waste, a study of the removal of iodide ion from radioactive waste using electrodialysis with an anion exchange paper membrane, in which trimethylhydroxylpropylammonium groups were homogeneously dispersed with high density. In Na125I and Na36Cl concentration-cell system, electric ion and water conductances, phenomenological coefficients, have been experimentally determined on basis of nonequilibrium thermodynamics. Prepared paper membrane had higher permselectivity of 125I ion than 36Cl ions by approximately 21%. On the other hand, water flux that was accompanied by an ionic transference in prepared paper membrane was greatly larger than that in typical synthesized membrane. It is suggested that a depression of water mobility is important to practice an ideal radioactive iodide waste electrodialysis system with a novel anion exchange paper membrane.

  16. Evaluation of automated and manual DNA purification methods for detecting Ricinus communis DNA during ricin investigations.

    PubMed

    Hutchins, Anne S; Astwood, Michael J; Saah, J Royden; Michel, Pierre A; Newton, Bruce R; Dauphin, Leslie A

    2014-03-01

    In April of 2013, letters addressed to the President of United States and other government officials were intercepted and found to be contaminated with ricin, heightening awareness about the need to evaluate laboratory methods for detecting ricin. This study evaluated commercial DNA purification methods for isolating Ricinus communis DNA as measured by real-time polymerase chain reaction (PCR). Four commercially available DNA purification methods (two automated, MagNA Pure compact and MagNA Pure LC, and two manual, MasterPure complete DNA and RNA purification kit and QIAamp DNA blood mini kit) were evaluated. We compared their ability to purify detectable levels of R. communis DNA from four different sample types, including crude preparations of ricin that could be used for biological crimes or acts of bioterrorism. Castor beans, spiked swabs, and spiked powders were included to simulate sample types typically tested during criminal and public health investigations. Real-time PCR analysis indicated that the QIAamp kit resulted in the greatest sensitivity for ricin preparations; the MasterPure kit performed best with spiked powders. The four methods detected equivalent levels by real-time PCR when castor beans and spiked swabs were used. All four methods yielded DNA free of PCR inhibitors as determined by the use of a PCR inhibition control assay. This study demonstrated that DNA purification methods differ in their ability to purify R. communis DNA; therefore, the purification method used for a given sample type can influence the sensitivity of real-time PCR assays for R. communis.

  17. Regulation of intracellular pH in rat lactotrophs: involvement of anionic exchangers.

    PubMed

    Garcia, L; Boué-Grabot, E; Garret, M; Sartor, P

    1997-10-01

    Regulation of the intracellular pH (pHi) of normal rat lactotrophs was studied. As this cell type, cultured with 10% FCS, can achieve a relatively alkaline pHi (7.3-7.5), we investigated the presence of a mechanism based on Cl-/HCO3- exchange. Using the pHi-sensitive probe SNARF-1 (seminaphtorodafluor) in its permeant form, SNARF-1/AM, we studied pHi recovery after acidic loading in individual cells with a microspectrofluorometric approach. We showed the involvement of anionic exchange in lactotroph cell pHi regulation. Acute CO2-bicarbonate cell acidic loading combined with external Cl- depletion induces the activation of a Cl-/HCO3- exchange. This exchange is 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid sensitive and corresponds to the type 3 anionic exchanger (AE3). However, after nigericin acidification, Na+/H+ exchange can also participate in recovery. In addition, incubation experiments strongly suggest that a 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid-insensitive anionic exchanger (type 2 anionic exchanger or AE2) is present in rat lactotrophs. The presence and involvement of carbonic anhydrase in pHi regulation have been demonstrated. Finally, using Northern blot and reverse transcription-PCR techniques, messenger RNAs for both AE2 and AE3 were identified in anterior pituitary cell extracts. We concluded that in normal rat lactotrophs, pHi regulation is achieved by a complex system in which Cl-/HCO3- exchange has a pivotal role.

  18. The dynamics of sorption of sulfuric acid by weakly basic polyacrylic anion exchangers

    NASA Astrophysics Data System (ADS)

    Mamchenko, A. V.; Kushnir, T. V.

    2009-05-01

    The nonequilibrium dynamics of sorption of sulfuric acid by free base forms of Amberlite IRA-67 and Lewatite VP.OC.1072 weakly basic anion exchangers is studied. It is established that, in hydrodynamic regimes of filtration, which are typical of OH filters of the first stage of water-desalting plants, the limiting stage of sorption kinetics is inside diffusion. It is concluded that the process is correctly described by an asymptotic solution to the inside-diffusion model of sorption dynamics.

  19. Removal and recovery of vanadium from alkaline steel slag leachates with anion exchange resins.

    PubMed

    Gomes, Helena I; Jones, Ashley; Rogerson, Mike; Greenway, Gillian M; Lisbona, Diego Fernandez; Burke, Ian T; Mayes, William M

    2017-02-01

    Leachable vanadium (V) from steel production residues poses a potential environmental hazard due to its mobility and toxicity under the highly alkaline pH conditions that characterise these leachates. This work aims to test the efficiency of anion exchange resins for vanadium removal and recovery from steel slag leachates at a representative average pH of 11.5. Kinetic studies were performed to understand the vanadium sorption process. The sorption kinetics were consistent with a pseudo-first order kinetic model. The isotherm data cannot differentiate between the Langmuir and Freundlich models. The maximum adsorption capacity (Langmuir value qmax) was 27 mg V g(-1) resin. In column anion exchange, breakthrough was only 14% of the influent concentration after passing 90 L of steel slag leachate with 2 mg L(-1) V through the column. When eluting the column 57-72% of vanadium was recovered from the resin with 2 M NaOH. Trials on the reuse of the anion exchange resin showed it could be reused 20 times without loss of efficacy, and on average 69% of V was recovered during regeneration. The results document for the first time the use of anion exchange resins to remove vanadium from steel slag leachate. As an environmental contaminant, removal of V from leachates may be an obligation for long-term management requirements of steel slag repositories. Vanadium removal coupled with the recovery can potentially be used to offset long-term legacy treatment costs.

  20. Anion exchangers with branched functional ion exchange layers of different hydrophilicity for ion chromatography.

    PubMed

    Shchukina, O I; Zatirakha, A V; Smolenkov, A D; Nesterenko, P N; Shpigun, O A

    2015-08-21

    Novel polystyrene-divinylbenzene (PS-DVB) based anion exchangers differing from each other in the structure of the branched functional ion exchange layer are prepared to investigate the role of linker and functional site on ion exchange selectivity. The proposed method of synthesis includes the obtaining of aminated PS-DVB particles by means of their acylation with following reductive amination with methylamine. Further modification of the obtained secondary aminogroups is provided by the alkylation with either 1,4-butanediol diglycidyl ether (1,4-BDDGE) or resorcinol diglycidyl ether (RDGE), which form the linkers of different hydrophobicity, and amination of terminal epoxide rings with trimethylamine (TMA), dimethylethanolamine (DMEA), methyldiethanolamine (MDEA) or triethanolamine (TEA). The variation of the structure and hydrophobicity of the linker and terminal quaternary ammonium sites in the functional layer allows the alteration of selectivity and separation efficiency of the obtained adsorbents. The ion exchange selectivity and separation efficiency of the anion exchangers are evaluated using the model mixtures of anions (F(-), HCOO(-), Cl(-), NO2(-), Br(-), NO3(-), HPO4(2-) and SO4(2-)) in potassium hydroxide eluents. The adsorbents show the decrease of selectivity with increasing the hydrophilicity of the terminal functional site. The anion exchangers having more flexible and hydrophilic 1,4-BDDGE linker provide smaller separation factors for most of the analytes as compared with RDGE-containing adsorbents with the same terminal ion exchange sites, but are characterized with higher column efficiencies and better peak symmetry for polarizable anions. In case of 1,4-BDDGE-modified anion exchangers of the particle size of 3.3μm functionalized with DMEA and MDEA the calculated values of column efficiencies for polarizable NO3(-) and Br(-) are up to 49,000 and 53,000N/m, respectively, which is almost twice higher than the values obtained for the RDGE

  1. Anion exchangers with negatively charged functionalities in hyperbranched ion-exchange layers for ion chromatography.

    PubMed

    Uzhel, Anna S; Zatirakha, Alexandra V; Smirnov, Konstantin N; Smolenkov, Alexandr D; Shpigun, Oleg A

    2017-01-27

    Novel pellicular poly(styrene-divinylbenzene)-based (PS-DVB) anion exchangers with covalently-bonded hyperbranched functional ion-exchange layers containing negatively charged functionalities are obtained and examined. The hyperbranched coating is created on the surface of aminated PS-DVB substrate by repeating the modification cycles including alkylation with 1,4-butanediol diglycidyl ether (1,4-BDDGE), and amination of the terminal epoxide rings with methylamine (MA) or glycine (Gly). The influence of the position and the number of the layers with glycine, as well as of the total number of the layers of amine in the coating on the chromatographic properties of the obtained stationary phases is investigated. Chromatographic performance of the obtained stationary phases is evaluated using the model mixtures of inorganic and organic anions with hydroxide eluent. It is shown that the best selectivity toward weakly retained organic acids and oxyhalides is possessed by the anion exchanger obtained after 5 modification cycles, with glycine being used in the first one. Such anion exchanger packed in 25-cm long column is capable of separating 22 anions in 58min including 7 standard anions, mono-, di- and trivalent organic acids, oxyhalides, and some other double- and triple-charged anions.

  2. Kinetic study of the mass transfer of bovine serum albumin in anion-exchange chromatography.

    PubMed

    Miyabe, K; Guiochon, G

    2000-01-14

    A kinetic study was made on the mass transfer phenomena of bovine serum albumin (BSA) in two different anion-exchange columns (Resource-Q and TSK-GEL-DEAE-5PW). The analysis of the concentration dependence of the lumped mass transfer rate coefficient (km,L) provided the information about the kinetics of the several mass transfer processes in the columns and the anion exchangers, i.e., the axial dispersion, the fluid-to-particle mass transfer, the intraparticle diffusion, and the adsorption/desorption. In the Resource-Q column, the intraparticle diffusion had a dominant contribution to the band broadening compared with those of the other processes. The surface diffusion coefficient (Ds) of BSA showed a positive concentration dependence, by which the linear dependence of km,L on the BSA concentration seemed to be interpreted. On the other hand, in the TSK-GEL-DEAE-5PW column, the contribution of the adsorption/desorption was also important and almost same as that due to the intraparticle diffusion. There are some differences between the intrinsic properties of the mass transfer kinetics inside the two anion exchangers. It was likely that the positive concentration dependence of Ds was explained by the heterogeneous surface model.

  3. Integrating tunable anion exchange with reverse osmosis for enhanced recovery during inland brackish water desalination.

    PubMed

    Smith, Ryan C; SenGupta, Arup K

    2015-05-05

    For inland brackish water desalination by reverse osmosis or RO, concentrate or reject disposal poses a major challenge. However, enhanced recovery and consequent reduction in the reject volume using RO processes is limited by the solubility of ions present in the feedwater. One of the most common and stubborn precipitate formed during desalination is calcium sulfate. Reducing or eliminating the presence of sulfate would allow the process to operate at higher recoveries without threat to membrane scaling. In this research, this goal is accomplished by using an appropriate mixture of self-regenerating anion exchange resins that selectively remove and replace sulfate by chloride prior to the RO unit. Most importantly, the mixed bed of anion exchange resins is self-regenerated with the reject brine from the RO process, thus requiring no addition of external chemicals. The current work demonstrates the reversibility of the hybrid ion exchange and RO (HIX-RO) process with 80% recovery for a brackish water composition representative of groundwater in San Joaquin Valley in California containing approximately 5200 mg/L of total dissolved solids or TDS. Consequently, the reject volume can be reduced by 50% without the threat of sulfate scaling and use of antiscaling chemicals can be eliminated altogether. By appropriately designing or tuning the mixed bed of anion exchange resins, the process can be extended to nearly any composition of brackish water for enhanced recovery and consequent reduction in the reject volume.

  4. Preparation, Characterization and Anion Exchange Properties of Polypyrrole/Carbon Nanotube Nanocomposite

    SciTech Connect

    Cui, Xiaoli; Engelhard, Mark H.; Lin, Yuehe

    2006-02-01

    In this study, polypyrrole (PPy) thin film was electrodeposited on carbon nanotube (CNT) backbones by applying a constant deposition potential in solution with 0.1 M pyrrole with different electrolytes such as NaCl, NaNO3, or NaClO4. The hybrid films were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry. SEM images revealed the nanostructrure of PPy film generated on CNTs surface. The electrochemical and anion exchange properties of PPy-CNT composite film have been investigated. Nanostructured composite thin films of polypyrrole/CNTs were studied by cyclic voltammetry between 0.4 and -0.8 V in aqueous solution to evaluate their cycling stability and capacity for electrically switched anion exchange. It is found that the PPy/CNTs nanocomposites can improve the anion exchange capacity and stability of the PPy-CNTs composite film, which may be attributed to the nanostructure of the polypyrrole film, which offer the high aspect ratio of the film and ease of diffusion of anions in the nanostructured film, and the interaction between CNTs and PPy.

  5. Optimization of SHINE Process: Design and Verification of Plant-Scale AG 1 Anion-Exchange Concentration Column and Titania Sorbent Pretreatment

    SciTech Connect

    Stepinski, Dominique C.; Abdul, Momen; Youker, Amanda J.; Rotsch, David A.; Tkac, Peter; Chemerisov, Sergey; Vandegrift, George F.

    2016-06-01

    Argonne National Laboratory has developed a Mo-recovery and -purification system for the SHINE medical technologies process, which uses a uranyl sulfate solution for the accelerator-driven production of Mo-99. The objective of this effort is to reduce the processing time for the acidification of the Mo-99 product prior to loading onto a concentration column and concentration of the Mo-99 product solution. Two methods were investigated: (1) the replacement of the titania concentration column by an anion-exchange column to decrease processing time and increase the radioiodine-decontamination efficiency and (2) pretreatment of the titania sorbent to improve its effectiveness for the Mo-recovery and -concentration columns. Promising results are reported for both methods.

  6. Hydration and sorption characteristics of a polyfunctional weak-base anion exchanger after the sorption of vanillin and ethylvanillin

    NASA Astrophysics Data System (ADS)

    Rodionova, D. O.; Voronyuk, I. V.; Eliseeva, T. V.

    2016-07-01

    Features of the sorption of substituted aromatic aldehydes by a weak-base anion exchanger under equilibrium conditions are investigated using vanillin and ethylvanillin as examples. Analysis of the sorption isotherms of carbonyl compounds at different temperatures allows us to calculate the equilibrium characteristics of their sorption and assess the entropy and enthalpy contributions to the energy of the process. Hydration characteristics of the macroporous weak-base anion exchanger before and after the sorption of aromatic aldehydes are compared.

  7. High-throughput sequential injection method for simultaneous determination of plutonium and neptunium in environmental solids using macroporous anion-exchange chromatography, followed by inductively coupled plasma mass spectrometric detection.

    PubMed

    Qiao, Jixin; Hou, Xiaolin; Roos, Per; Miró, Manuel

    2011-01-01

    This paper reports an automated analytical method for rapid and simultaneous determination of plutonium and neptunium in soil, sediment, and seaweed, with detection via inductively coupled plasma mass spectrometry (ICP-MS). A chromatographic column packed with a macroporous anion exchanger (AG MP-1 M) was incorporated in a sequential injection (SI) system for the efficient retrieval of plutonium, along with neptunium, from matrix elements and potential interfering nuclides. The sorption and elution behavior of plutonium and neptunium onto AG MP-1 M resin was compared with a commonly utilized AG 1-gel-type anion exchanger. Experimental results reveal that the pore structure of the anion exchanger plays a pivotal role in ensuring similar separation behavior of plutonium and neptunium along the separation protocol. It is proven that plutonium-242 ((242)Pu) performs well as a tracer for monitoring the chemical yield of neptunium when using AG MP-1 M resin, whereby the difficulties in obtaining a reliable and practicable isotopic neptunium tracer are overcome. An important asset of the SI setup is the feasibility of processing up to 100 g of solid substrates using a small-sized (ca. 2 mL) column with chemical yields of neptunium and plutonium being ≥79%. Analytical results of three certified/standard reference materials and two solid samples from intercomparison exercises are in good agreement with the reference values at the 0.05 significance level. The overall on-column separation can be completed within 3.5 h for 10 g of soil samples. Most importantly, the anion-exchange mini-column suffices to be reused up to 10-fold with satisfactory chemical yields (>70%), as demanded in environmental monitoring and emergency scenarios, making the proposed automated assembly well-suited for unattended and high-throughput analysis.

  8. Removal of fluorescent dissolved organic matter in biologically treated textile effluents by NDMP anion exchange process: efficiency and mechanism.

    PubMed

    Li, Wen-Tao; Xu, Zi-Xiao; Shuang, Chen-Dong; Zhou, Qing; Li, Hai-Bo; Li, Ai-Min

    2016-03-01

    The efficiency and mechanism of anion exchange resin Nanda Magnetic Polymer (NDMP) for removal of fluorescent dissolved organic matter in biologically treated textile effluents were studied. The bench-scale experiments showed that as well as activated carbon, anion exchange resin could efficiently remove both aniline-like and humic-like fluorescent components, which can be up to 40 % of dissolved organic matter. The humic-like fluorescent component HS-Em460-Ex3 was more hydrophilic than HS-Em430-Ex2 and contained fewer alkyl chains but more acid groups. As a result, HS-Em460-Ex3 was eliminated more preferentially by NDMP anion exchange. However, compared with adsorption resins, the polarity of fluorescent components had a relatively small effect on the performance of anion exchange resin. The long-term pilot-scale experiments showed that the NDMP anion exchange process could remove approximately 30 % of the chemical oxygen demand and about 90 % of color from the biologically treated textile effluents. Once the issue of waste brine from resin desorption is solved, the NDMP anion exchange process could be a promising alternative for the advanced treatment of textile effluents.

  9. Retention behavior of C1-C6 aliphatic monoamines on anion-exchange and polymethacrylate resins with heptylamine as eluent.

    PubMed

    Ohta, Kazutoku; Ohashi, Masayoshi; Jin, Ji-Ye; Takeuchi, Toyohide; Fujimoto, Chuzo; Choi, Seong-Ho; Ryoo, Jae Jeong; Lee, Kwang-Pill

    2004-06-11

    Retention behavior of C1-C6, aliphatic monoamines (methylamine, ethylamine, propylamine, butylamine, amylamine and hexylamine) on columns (150 mm x 6 mm i.d.) packed with various anion-exchange resins (styrene-divinylbenzene (PS-DVB) copolymer-based strongly basic anion-exchange resin: TSKgel SAX, polymethacrylate-based strongly basic anion-exchange resin: TSKgel SuperQ-5PW and polymethacrylate-based weakly basic anion-exchange resin: TSKgel DEAE-5PW) and unfunctionized polymethacrylate resins (TSKgel G5000PW and TSKgel G3000PWXL) was investigated with basic solutions (sodium hydroxide and heptylamine) as the eluents. Due to strongly electrostatic repulsion (ion-exclusion effect) between these anion-exchange resins and these amines, peak resolution between these amines on these anion-exchange resin columns was unsatisfactory with both sodium hydroxide and heptylamine as the eluents. In contrast, these polymethacrylate resins were successfully applied as the stationary phases for the separation of these C1-C6 amines with heptylamine as eluent, because of both small hydrophobicity and small cation-exchange ability of these resins. Excellent simultaneous separation, highly sensitive conductimetric detection and symmetrical peaks for these C1-C6 amines were achieved on the TSKgel G3000PWXL column in 35 min with 5 mM heptylamine at pH 11.1 as the eluent.

  10. Mono- and polyprotic buffer systems in anion exchange chromatography of influenza virus particles.

    PubMed

    Vajda, Judith; Weber, Dennis; Stefaniak, Sabine; Hundt, Boris; Rathfelder, Tanja; Müller, Egbert

    2016-05-27

    Different ions typically used in downstream processing of biologicals are evaluated for their potential in anion exchange chromatography of an industrially produced, pandemic influenza H1N1 virus. Capacity, selectivity and recovery are investigated based on single step elution parallel chromatography experiments. The inactivated H1N1 feedstream is produced in Madin-Darby Bovine Kidney cells. Interesting effects are found for sodium phosphate and sodium citrate. Both anions are triprotic kosmotropes. Anion exchange chromatography generally offers high scalability to satisfy sudden demands for vaccines, which may occur in case of an emerging influenza outbreak. Appropriate pH conditions for H1N1 adsorption are determined by Zeta potential measurements. The dynamic binding capacity of a salt tolerant polyamine-type resin is up to 6.4 times greater than the capacity of a grafted Q-type resin. Pseudo-affinity interactions of polyamines with the M2 protein of influenza may contribute to the obtained capacity increase. Both resins achieve greater capacity in sodium phosphate buffer compared to Tris/HCl. A recovery of 67% and DNA clearance close to 100% without DNAse treatment are achieved for the Q-type resin. Recovery of the virus from the salt tolerant resin requires the use of polyprotic acids in the elution buffer. 85% of the DNA and 60% of the proteins can be removed by the salt tolerant resin. The presence of sodium phosphate during anion exchange chromatography seems to support stability of the H1N1 particles in presence of hydrophobic cations.

  11. Anion exchange through band 3 protein in canine leishmaniasis at different stages of disease.

    PubMed

    Morabito, Rossana; Remigante, Alessia; Cavallaro, Mauro; Taormina, Alessandro; La Spada, Giuseppina; Marino, Angela

    2017-04-05

    Band 3 protein efficiency in mediating Cl(-)/HCO3(-) exchange through erythrocytes membrane is reduced by oxidative stress. The aim of the present study was to verify whether and how anion transport through band 3 protein may be useful in monitoring canine leishmaniasis (Leishmania infantum) development, a disease associated to membrane protein degradation and oxidative stress. To accomplish this aim, serological analysis to determine IFAT (immunofluorescence antibody test) titers against leishmaniasis has been performed and 1:160 and 1:540 titers, determined at diagnosis and after 6 months, were considered for experiments. Oxidative conditions have been assessed by estimating MDA (malondialdehyde) plasma levels, intracellular GSH (reduced glutathione) content, and membrane -SH groups. Band 3 protein anion exchange capability was evaluated by measuring the rate constant for SO4(=) uptake, and its expression levels, along with those of P-Tyr (phosphorylated tyrosine), involved in pathways underlying band 3 protein function, have been also determined. Our results show that, in infected dogs with 1:160 IFAT titer, high MDA plasma levels and oxidation of -SH groups are associated to increased P-Tyr expression levels, leading to a reduction in anion exchange capability throughout 6 months of diagnosis. On the other hand, infected dogs with 1:540 IFAT titer, exhibited oxidative conditions associated to an impaired anion exchange capability at diagnosis, were ameliorated after 6 months. Such findings suggest that (1) band 3 protein-mediated anion transport is reduced by oxidative conditions associated to leishmaniasis, putatively via phosphorylative pathways; (2) band 3 protein efficiency may account for canine leishmaniasis development; and (3) the assessment of band 3 protein function may represent an additional tool for canine leishmaniasis diagnosis and monitoring of its development, with potential application to humans, either in case of leishmaniasis or other

  12. Kinetically controlled patterning of highly cross-linked phosphonium photopolymers using simple anion exchange.

    PubMed

    Guterman, Ryan; Gillies, Elizabeth R; Ragogna, Paul J

    2015-05-12

    A phosphonium salt possessing three methacrylate groups has been incorporated into a photopolymeric system to generate highly cross-linked polyelectrolyte networks. Emergent chemical and physical properties in the polymers were observed and attributed to the tandem increase in cross-link density and ion-content upon incorporation of the self-cross-linking cation. Anion-exchange with bis(trifluoromethylsulfonyl)imide or dodecylbenzenesulfonate resulted in significant differences in wettability and ion-exchange behavior. The passivating effects of dodecylbenzenesulfonate were utilized to selectively pattern fluorescein dye into the polymer network, highlighting a new patterning procedure using ionic-bond forming reactions.

  13. Determination of traces of silver in waters by anion exchange and atomic absorption spectrophotometry

    USGS Publications Warehouse

    Chao, T.T.; Fishman, M. J.; Ball, J.W.

    1969-01-01

    A method has been developed for the accurate determination of 0.1-1 ??g of silver per liter of water. The method permits stabilization of silver in water without loss to container walls. Optimum conditions have been established for the complete recovery of silver from water with an anion-exchange column, for quantitative elution of silver from the resin, and for measurement of silver by atomic absorption spectrophotometry after chelation with ammonium pyrrolidine dithiocarbamate and extraction of the chelate with MIBK. Silver in the 1-10 ??g 1 range can be determined by extraction without pre-concentration on an ion-exchange resin. ?? 1969.

  14. Bifunctional anion-exchange resins with improved selectivity and exchange kinetics

    DOEpatents

    Alexandratos, Spiro D.; Brown, Gilbert M.; Bonnesen, Peter V.; Moyer, Bruce A.

    2000-01-01

    Disclosed herein are a class of anion exchange resins containing two different exchange sites with improved selectivity and sorptive capability for chemical species in solution, such as heptavalent technetium (as pertechnetate anion, TcO.sub.4.sup.-). The resins are prepared by first reacting haloalkylated crosslinked copolymer beads with a large tertiary amine in a solvent in which the resin beads can swell, followed by reaction with a second, smaller, tertiary amine to more fully complete the functionalization of the resin. The resins have enhanced selectivity, capacity, and exchange kinetics.

  15. TREATMENT FOR IMPROVING THE OPERATION OF STRONG BASE ANION EXCHANGE RESINS

    DOEpatents

    Stevenson, P.C.

    1960-11-29

    A process is offered for improving quaternary ammonium type strongly basic anion exchange resins so that centain zinc and cadmium residues, which normally stick to and "poison" this type of resin, can be removed by elution. Specifically, the resin as obtained commercially is treated with an aqueous solution of sodium hydroxide of about 1 to 4 M concentration by heating therein and periodically adding small amounts of oxidizing agent selected from hydrogen peroxide, sodium peroxide and hypochlorite. Zinc and cadmium values may then be adsorbed onto the resin from a 0.1 to 3 M HCl and thereafter eluted therefrom with very dilute HCl solutions.

  16. Relationships of anion-exchange sorption of boron from natural thermal-spring water

    SciTech Connect

    Meichik, N.R.; Leikin, Yu.A.; Antipov, M.A.; Goryacheva, N.V.; Klimenko, I.S.; Medvedev, S.A.; Galitskaya, N.B.

    1988-02-20

    Boric acid is one of the characteristic components of Kamchatka waters. Extraction of boron from thermal waters for production of potable water is closely linked with current problems of multiproduct utilization of resources and protection of the environment. The authors have investigated the possibilities of using ion exchange for extraction of boron from natural waters, and studied the sorption relationships by a dynamic method. They synthesized a macroporous anion-exchanger based on a copolymer of styrene with divinylbenzene, containing N-methylglucamine groups (ANB-11 resin). ANB-11 resin had high sorption capacity for boron anions during sorption from thermal-spring water. The experimental data were described by Elkins equation.

  17. New Gel-Like Polymers as Selective Weak-Base Anion Exchangers

    PubMed Central

    Gierczyk, Błażej; Cegłowski, Michał; Zalas, Maciej

    2015-01-01

    A group of new anion exchangers, based on polyamine podands and of excellent ion-binding capacity, were synthesized. The materials were obtained in reactions between various poly(ethyleneamines) with glycidyl derivatives of cyclotetrasiloxane. The final polymeric, strongly cross-linked materials form gel-like solids. Their structures and interactions with anions adsorbed were studied by spectroscopic methods (CP-MAS NMR, FR-IR, UV-Vis). The sorption isotherms and kinetic parameters were determined for 29 anions. Materials studied show high ion capacity and selectivity towards some important anions, e.g., selenate(VI) or perrhenate. PMID:25946220

  18. Donnan dialysis of transition metal ions using anion exchange membrane modified with Xylenol Orange

    SciTech Connect

    Sawicka, B.; Brajter, K.; Trojanowicz, M.; Kado, B. )

    1991-01-01

    A chelating ion-exchange membrane was obtained by modification of a PTFE-based anion-exchange membrane with Xylenol Orange. Its utility for dialysis of Cu(II), Ni(II), Mn(II), and Zn(II) was investigated by using receiver solutions without and with iminodiacetate. 1,2-diaminocyclohexanetetraacetic acid, and tetraethylenepentamine. In comparison to commercial PTFE cation-exchange membranes, modified chelating membranes exhibit for the metal ions investigated a larger differentiation of retention in the membrane phase and transport-to-receiver solution depending on the modifier used and the composition of the receiver solution.

  19. Removal of fluoride from water using anion-exchange membrane under Donnan dialysis condition.

    PubMed

    Tor, Ali

    2007-03-22

    The transport of fluoride through Neosepta-ACM anion-exchange membrane has been studied as a function of feed phase and receiver phase concentration and co-existence anions under Donnan dialysis condition. It was observed that the transport of fluoride was maximum at pH 6 of feed phase and at pH 1 of receiver phase. Moreover, transport of fluoride increased with increase of feed and receiver phase concentration and decreased in the presence of other co-existence anions in the feed phase. The transport of fluoride was also correlated with the flux data and explained according to structure of membrane.

  20. Bifunctional anion-exchange resins with improved selectivity and exchange kinetics

    SciTech Connect

    Alexandratos, S.D.; Brown, G.M.; Bonnesen, P.V.; Moyer, B.A.

    2000-05-09

    Disclosed herein are a class of anion exchange resins containing two different exchange sites with improved selectivity and sorptive capability for chemical species in solution, such as heptavalent technetium as pertechnetate anion, TcO{sub 4}{sup {minus}}. The resins are prepared by first reacting haloalkylated crosslinked copolymer beads with a large tertiary amine in a solvent in which the resin beads can swell, followed by reaction with a second, smaller, tertiary amine to more fully complete the functionalization of the resin. The resins have enhanced selectivity, capacity, and exchange kinetics.

  1. Anion-exchange method for determination of phytate in foods: collaborative study.

    PubMed

    Harland, B F; Oberleas, D

    1986-01-01

    Phytate, a naturally occurring organic compound found in plant seeds, roots, and tubers, was determined in a collaborative study using a modified anion-exchange method. Seven samples (peanut flour, oats, rice, isolated soybean protein, a vegetarian diet composite, wheat bran, and whole wheat bread), supplied as blind duplicate samples, were analyzed in triplicate by 7 collaborators. Phytate concentrations in the samples ranged from 2.38 to 46.70 mg/g. Relative standard deviations (RSD = CV) for repeatability ranged from 2.5 to 10.1%, and for reproducibility, from 4.5 to 11.0%. The method has been adopted official first action.

  2. An instrument for automated purification of nucleic acids from contaminated forensic samples.

    PubMed

    Broemeling, David J; Pel, Joel; Gunn, Dylan C; Mai, Laura; Thompson, Jason D; Poon, Hiron; Marziali, Andre

    2008-02-01

    Forensic crime scene sample analysis, by its nature, often deals with samples in which there are low amounts of nucleic acids, on substrates that often lead to inhibition of subsequent enzymatic reactions such as PCR amplification for STR profiling. Common substrates include denim from blue jeans, which yields indigo dye as a PCR inhibitor, and soil, which yields humic substances as inhibitors. These inhibitors frequently co-extract with nucleic acids in standard column or bead-based preps, leading to frequent failure of STR profiling. We present a novel instrument for DNA purification of forensic samples that is capable of highly effective concentration of nucleic acids from soil particulates, fabric, and other complex samples including solid components. The novel concentration process, known as SCODA, is inherently selective for long charged polymers such as DNA, and therefore is able to effectively reject known contaminants. We present an automated sample preparation instrument based on this process, and preliminary results based on mock forensic samples.

  3. Automated forensic DNA purification optimized for FTA card punches and identifiler STR-based PCR analysis.

    PubMed

    Tack, Lois C; Thomas, Michelle; Reich, Karl

    2007-03-01

    Forensic labs globally face the same problem-a growing need to process a greater number and wider variety of samples for DNA analysis. The same forensic lab can be tasked all at once with processing mixed casework samples from crime scenes, convicted offender samples for database entry, and tissue from tsunami victims for identification. Besides flexibility in the robotic system chosen for forensic automation, there is a need, for each sample type, to develop new methodology that is not only faster but also more reliable than past procedures. FTA is a chemical treatment of paper, unique to Whatman Bioscience, and is used for the stabilization and storage of biological samples. Here, the authors describe optimization of the Whatman FTA Purification Kit protocol for use with the AmpFlSTR Identifiler PCR Amplification Kit.

  4. Anion exchange strategy to synthesis of porous NiS hexagonal nanoplates for supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Zhongchun; Yu, Xuewei; Gu, Aijun; Tang, Huang; Wang, Liangbiao; Lou, Zhengsong

    2017-02-01

    A facile anion exchange strategy was applied to the synthesis of porous NiS hexagonal nanoplates (NiS HNPs) as an electrode material for supercapacitors. It was found that Na2S concentration is a key factor to achieve porous NiS hexagonal nanoplates with well-defined architecture. Porous NiS hexagonal nanoplates exhibited a specific capacitance of 1897 F g-1 at a current density of 1 A g-1. NiS HNPs//activated carbon (AC) asymmetric supercapacitor (ASC) shows a long cycle lifespan (about 100% capacity retention after 4000 cycles at a current density of 3 A g-1) with a maximum energy density of 11.6 Wh kg-1 at a large loading mass of about 30 mg. Impressively, two NiS HNPs//AC ASCs in series could light up a red LED for about 30 min. The remarkable electrochemical performance of NiS HNPs is ascribed to their unique hierarchical porous architectures. The anion exchange method is a facile and versatile strategy for the synthesis of metal sulfides with high performance for energy storage.

  5. Highly conductive anion exchange membrane for high power density fuel-cell performance.

    PubMed

    Ren, Xiaoming; Price, Samuel C; Jackson, Aaron C; Pomerantz, Natalie; Beyer, Frederick L

    2014-08-27

    Anion exchange membrane fuel cells (AEMFCs) are regarded as a new generation of fuel cell technology that has the potential to overcome many obstacles of the mainstream proton exchange membrane fuel cells (PEMFCs) in cost, catalyst stability, efficiency, and system size. However, the low ionic conductivity and poor thermal stability of current anion exchange membranes (AEMs) have been the key factors limiting the performance of AEMFCs. In this study, an AEM made of styrenic diblock copolymer with a quaternary ammonium-functionalized hydrophilic block and a cross-linkable hydrophobic block and possessing bicontinuous phases of a hydrophobic network and hydrophilic conduction paths was found to have high ionic conductivity at 98 mS cm(-1) and controlled membrane swelling with water uptake at 117 wt % at 22 °C. Membrane characterizations and fuel cell tests of the new AEM were carried out together with a commercial AEM, Tokuyama A201, for comparison. The high ionic conductivity and water permeability of the new membrane reported in this study is attributed to the reduced torturosity of the ionic conduction paths, while the hydrophobic network maintains the membrane mechanical integrity, preventing excessive water uptake.

  6. Anion exchange nanofiber materials activated by daylight with a dual antibacterial effect.

    PubMed

    Plíštil, L; Henke, P; Kubát, P; Mosinger, J

    2014-09-01

    Anion exchange polystyrene nanofiber materials (AE) were prepared by electrospinning followed by two-step functionalization of the nanofiber surface by chlorosulfonic acid and ethylendiamine. The photoactive character of these materials was introduced through adsorption of the tetra-anionic 5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrin photosensitizer (TPPS-AE) on the nanofiber surface or by encapsulation of the nonpolar 5,10,15,20-tetraphenylporphyrin photosensitizer (AE(TPP)) into the nanofibers. Anion exchange nanofiber materials with porphyrins are characterized by a high ion-exchange capacity, photogeneration of singlet oxygen O2((1)Δg), and singlet oxygen-sensitized delayed fluorescence. Due to the photogeneration of cytotoxic O2((1)Δg), the nanofibers exhibited oxidation of the external substrates in aqueous solution and an efficient antibacterial effect when activated by simulated daylight. Adsorption of both TPPS and I(-) on the surface of AE led to the formation of more efficient I-TPPS-AE materials. Rapid photooxidation of I(-) by O2((1)Δg), and the formation of another cytotoxic species, I3(-), on the surface of the nanofibers were responsible for the increased antibacterial properties of I-TPPS-AE and the prolonged antibacterial effect in the dark.

  7. A green approach for preparing anion exchange membrane based on cardo polyetherketone powders

    NASA Astrophysics Data System (ADS)

    Hu, Jue; Zhang, Chengxu; Zhang, Xiaodong; Chen, Longwei; Jiang, Lin; Meng, Yuedong; Wang, Xiangke

    2014-12-01

    Anion exchange membranes (AEMs) have attracted great attention due to their irreplaceable role in platinum-free fuel cell applications. The majority of AEM preparations have been performed in two steps: the grafting of functional groups and quaternization. Here, we adopted a simpler, more eco-friendly approach for the first time to prepare AEMs by atmospheric-pressure plasma-grafting. This approach enables the direct introduction of anion exchange groups (benzyltrimethylammonium groups) into the polymer matrix, overcoming the need for toxic chloromethyl ether and quaternization reagents. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and 1H NMR spectroscopy results demonstrate that benzyltrimethylammonium groups have been successfully grafted into the cardo polyetherketone (PEK-C) matrix. Thermogravimetric analysis reveals that the plasma-grafting technique is a facile and non-destructive method able to improve the thermal stability of the polymer matrix due to the strong preservation of the PEK-C backbone structure and the cross-linking of the grafted side chains. The plasma-grafted PG-NOH membrane, which shows satisfactory alcohol resistance (ethanol permeability of 6.3 × 10-7 cm2 s-1), selectivity (1.2 × 104 S s cm-3), thermal stability (safely used below 130 °C), chemical stability, anion conductivity (7.7 mS cm-1 at 20 °C in deionized water) and mechanical properties is promising for the construction of high-performance fuel cells.

  8. Enhanced removal of fluoride by polystyrene anion exchanger supported hydrous zirconium oxide nanoparticles.

    PubMed

    Pan, Bingcai; Xu, Jingsheng; Wu, Bing; Li, Zhigang; Liu, Xitong

    2013-08-20

    Here we fabricated a novel nanocomposite HZO-201, an encapsulated nanosized hydrous zirconium oxide (HZO) within a commercial porous polystyrene anion exchanger D201, for highly efficient defluoridation of water. HZO-201 exhibited much higher preference than activated alumina and D201 toward fluoride removal when competing anions (chloride, sulfate, nitrate, and bicarbonate) coexisted at relatively high levels. Fixed column adsorption indicated that the effective treatable volume of water with HZO-201 was about 7-14 times as much as with D201 irrespective of whether synthetic solution or groundwater was the feeding solution. In addition, HZO-201 could treat >3000 BV of the acidic effluent (around 3.5 mg F(-)/L) per run at pH 3.5, compared to only ∼4 BV with D201. The exhausted HZO-201 could be regenerated by NaOH solution for repeated use without any significant capacity loss. Such attractive performance of HZO-201 resulted from its specific hybrid structure, that is, the host anion exchanger D201 favors the preconcentration of fluoride ions inside the polymer based on the Donnan principle, and the encapsulated nanosized HZO exhibits preferable sequestration of fluoride through specific interaction, as further demonstrated by XPS spectra. The influence of solution pH, competitive anions, and contact time was also examined. The results suggested that HZO-201 has a great potential in efficient defluoridation of groundwater and acidic mine drainage.

  9. Phosphorus recovery from microbial biofuel residual using microwave peroxide digestion and anion exchange.

    PubMed

    Gifford, McKay; Liu, Jianyong; Rittmann, Bruce E; Vannela, Raveender; Westerhoff, Paul

    2015-03-01

    Sustainable production of microalgae for biofuel requires efficient phosphorus (P) utilization, which is a limited resource and vital for global food security. This research tracks the fate of P through biofuel production and investigates P recovery from the biomass using the cyanobacterium Synechocystis sp. PCC 6803. Our results show that Synechocystis contained 1.4% P dry weight. After crude lipids were extracted (e.g., for biofuel processing), 92% of the intracellular P remained in the residual biomass, indicating phospholipids comprised only a small percentage of cellular P. We estimate a majority of the P is primarily associated with nucleic acids. Advanced oxidation using hydrogen peroxide and microwave heating released 92% of the cellular P into orthophosphate. We then recovered the orthophosphate from the digestion matrix using two different types of anion exchange resins. One resin impregnated with iron nanoparticles adsorbed 98% of the influent P through 20 bed volumes, but only released 23% during regeneration. A strong-base anion exchange resin adsorbed 87% of the influent P through 20 bed volumes and released 50% of it upon regeneration. This recovered P subsequently supported growth of Synechocystis. This proof-of-concept recovery process reduced P demand of biofuel microalgae by 54%.

  10. Removal of tartrazine from aqueous solutions by strongly basic polystyrene anion exchange resins.

    PubMed

    Wawrzkiewicz, Monika; Hubicki, Zbigniew

    2009-05-30

    The removal of tartrazine from aqueous solutions onto the strongly basic polystyrene anion exchangers of type 1 (Amberlite IRA-900) and type 2 (Amberlite IRA-910) was investigated. The experimental data obtained at 100, 200, 300 and 500 mg/dm(3) initial concentrations at 20 degrees C were applied to the pseudo-first order, pseudo-second order and Weber-Morris kinetic models. The calculated sorption capacities (q(e,cal)) and the rate constant of the first order adsorption (k(1)) were determined. The pseudo-second order kinetic constants (k(2)) and capacities were calculated from the plots of t/q(t) vs. t, 1/q(t) vs. 1/t, 1/t vs. 1/q(t) and q(t)/t vs. q(t) for type 1, type 2, type 3 and type 4 of the pseudo-second order expression, respectively. The influence of phase contact time, solution pH and temperature on tartrazine removal was also discussed. The FTIR spectra of pure anion exchangers and those loaded with tartrazine were recorded, too.

  11. Bioregeneration of spent anion exchange resin for treatment of nitrate in water.

    PubMed

    Meng, Xiaoyang; Vaccari, David A; Zhang, Jianfeng; Fiume, Antonio; Meng, Xiaoguang

    2014-01-01

    Anion exchange resin treatment is a commonly used technique for removal of nitrate from water. However, spent anion exchange resins are themselves regenerated using brine solution, which produces spent solution containing a high concentration of nitrate and salt. The present study developed a bioregeneration technique for conversion of nitrate on the spent resins to nitrogen gas while eliminating the use of brine solutions. Batch experiments were conducted to investigate the effect of biomass content, pH, salinity, and molar ratio of exogenous organic carbon to nitrate on the kinetics of bioregeneration. The bioregeneration rate decreased when pH increased from 7 to 10. It increased with increasing microbial concentration from 8.3 to 13.8 g/L as volatile suspended solid (VSS) and with decreasing conductivity of the regeneration suspension from 31 to 9 mS/cm. Spent exchange resins were effectively regenerated within 5 h under the optimal conditions and the regenerated resins could be used repeatedly for filtration removal of nitrate from water. A desorption-denitrification model was developed to describe bioregeneration kinetics. Modeling results indicated that the bioregeneration was through desorption of nitrate from the spent resin and subsequent denitrification of the soluble nitrate. Denitrification was the rate-limiting process. This research demonstrated the feasibility of using a biological process to regenerate nitrate-saturated resins.

  12. A novel self-adaptive microalgae photobioreactor using anion exchange membranes for continuous supply of nutrients.

    PubMed

    Fu, Qian; Chang, Hai-Xing; Huang, Yun; Liao, Qiang; Zhu, Xun; Xia, Ao; Sun, Ya-Hui

    2016-08-01

    A novel self-adaptive microalgae photobioreactor using anion exchange membranes (AEM-PBR) for continuous supply of nutrients was proposed to improve microalgae biomass production. The introduction of anion exchange membranes to the PBR can realize continuous supply of nutrients at desired rates, which is beneficial to the growth of microalgae. The results showed that the maximum biomass concentration obtained in the AEM-PBR under continuous supply of nitrogen at an average rate of 19.0mgN/L/d was 2.98g/L, which was 129.2% higher than that (1.30g/L) in a PBR with all the nitrogen supplied in batch at initial. In addition, the feeding rates of nitrogen and phosphorus were optimized in the AEM-PBR to maximize biomass production. The maximum biomass concentration of 4.38g/L was obtained under synergistic regulation of nitrogen and phosphorus feeding rates at 19.0mgN/L/d and 4.2mgP/L/d. The AEM-PBR demonstrates a promising approach for high-density cultivation of microalgae.

  13. Microcalorimetric study of adsorption of glycomacropeptide on anion-exchange chromatography adsorbent.

    PubMed

    Lira, Rafael A; Minim, Luis A; Bonomo, Renata C F; Minim, Valéria P R; da Silva, Luis H M; da Silva, Maria C H

    2009-05-15

    The adsorption of glycomacropeptide (GMP) from cheese whey on an anion-exchange adsorbent was investigated using isothermal titration microcalorimetry to measure thermodynamic information regarding such processes. Isotherms data were measured at temperatures of 25 and 45 degrees C, pH 8.2 and various ionic strengths (0-0.08 molL(-1) NaCl). The equilibrium data were fit using the Langmuir model and the process was observed to be reversible. Temperature was observed to positively affect the interaction of the protein and adsorbent. Microcalorimetric studies indicated endothermic adsorption enthalpy in all cases, except at 45 degrees C and 0.0 molL(-1) NaCl. The adsorption process was observed to be entropically driven at all conditions studied. It was concluded that the increase in entropy, attributed to the release of hydration waters as well as bounded ions from the adsorbent and protein surface due to interactions of the protein and adsorbent, was a major driving force for the adsorption of GMP on the anion-exchange adsorbent. These results could allow for design of more effective ion-exchange separation processes for proteins.

  14. Sorption of uranium(VI) ions from hydrochloric acid and ammonium chloride solutions by anion exchangers

    SciTech Connect

    Pakholkov, V.S.; Denisova, L.A.; Rychkov, V.N.; Kurnosenko, N.A.

    1988-01-01

    The sorption of macroscopic quantities of uranium from solutions of UO/sub 2/Cl/sub 2/ containing HCl and NH/sub 4/Cl in concentrations from 0.0 to 6.0 M by the AV-17 x 8, AV-16G, EDE-10P, AN-31, AN-2F, AN22, and AN-251 anion exchangers has been investigated under static conditions. The sorption isotherms are described by an equation similar to Freundlich's equation: K/sub d/ = K tilde x C/sub eq/sup 1/z/ or log K/sub d/ = log K tilde + 1/z x log C/sub eq/. Equations describing the dependence of the sorbability (or K/sub d/) on the equilibrium concentration of uranium in the solution have been obtained with the aid of the least-squares method. Conclusions regarding the chemistry of the exchange of uranium ions on anion exchangers in chloride solutions have been drawn on the basis of the UV spectra of the original solutions and the IR spectra of the ion exchangers obtained in this work, as well as the established general laws governing sorption.

  15. The recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor.

    PubMed

    Ren, Xiulian; Wei, Qifeng; Hu, Surong; Wei, Sijie

    2010-09-15

    This paper reports the optimization of the process parameters for recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor. The experiments were carried out in an ammoniacal ammonium chloride system. The influence of composition of electrolytes, pH, stirring rate, current density and temperature, on cathodic current efficiency, specific power consumption and anodic dissolution of Zn were investigated. The results indicate that the cathode current efficiency increases and the hydrogen evolution decreased with increasing the cathode current density. The partial current for electrodeposition of Zn has liner relationship with omega(1/2) (omega: rotation rate). The highest current efficiency for dissolving zinc was obtained when NH(4)Cl concentration was 53.46 g L(-1) and the anodic dissolution of zinc was determined by mass transfer rate at stirring rate 0-300 r min(-1). Increase in temperature benefits to improve CE and dissolution of Zn, and reduce cell voltage. Initial pH of electrolytes plays an important role in the deposition and anodic dissolution of Zn. The results of single factor experiment show that about 50% energy consumption was saved for electrodeposition of Zn in the anion-exchange membrane electrolysis reactor.

  16. Controlling Disorder and Superconductivity in Titanium Oxynitride Nanoribbons with Anion Exchange.

    PubMed

    Sluban, Melita; Umek, Polona; Jagličić, Zvonko; Buh, Jože; Šmitek, Petra; Mrzel, Aleš; Bittencourt, Carla; Guttmann, Peter; Delville, Marie-Helene; Mihailović, Dragan; Arčon, Denis

    2015-10-27

    In recent years, conversion chemical reactions, which are driven by ion diffusion, emerged as an important concept for formation of nanoparticles. Here we demonstrate that the slow anion diffusion in anion exchange reactions can be efficiently used to tune the disorder strength and the related electronic properties of nanoparticles. This paradigm is applied to high-temperature formation of titanium oxynitride nanoribbons, Ti(O,N), transformed from hydrogen titanate nanoribbons in an ammonia atmosphere. The nitrogen content, which determines the chemical disorder through random O/N occupancy and ion vacancies in the Ti(O,N) composition, increases with the reaction time. The presence of disorder has paramount effects on resistivity of Ti(O,N) nanoribbons. Atypically for metals, the resistivity increases with decreasing temperature due to the weak localization effects. From this state, superconductivity develops below considerably or completely suppressed critical temperatures, depending on the disorder strength. Our results thus establish the remarkable versatility of anion exchange for tuning of the electronic properties of Ti(O,N) nanoribbons and suggest that similar strategies may be applied to a vast number of nanostructures.

  17. Topology of the membrane domain of human erythrocyte anion exchange protein, AE1.

    PubMed

    Fujinaga, J; Tang, X B; Casey, J R

    1999-03-05

    Anion exchanger 1 (AE1) is the chloride/bicarbonate exchange protein of the erythrocyte membrane. By using a combination of introduced cysteine mutants and sulfhydryl-specific chemistry, we have mapped the topology of the human AE1 membrane domain. Twenty-seven single cysteines were introduced throughout the Leu708-Val911 region of human AE1, and these mutants were expressed by transient transfection of human embryonic kidney cells. On the basis of cysteine accessibility to membrane-permeant biotin maleimide and to membrane-impermeant lucifer yellow iodoacetamide, we have proposed a model for the topology of AE1 membrane domain. In this model, AE1 is composed of 13 typical transmembrane segments, and the Asp807-His834 region is membrane-embedded but does not have the usual alpha-helical conformation. To identify amino acids that are important for anion transport, we analyzed the anion exchange activity for all introduced cysteine mutants, using a whole cell fluorescence assay. We found that mutants G714C, S725C, and S731C have very low transport activity, implying that this region has a structurally and/or catalytically important role. We measured the residual anion transport activity after mutant treatment with the membrane-impermeant, cysteine-directed compound, sodium (2-sulfonatoethyl)methanethiosulfonate) (MTSES). Only two mutants, S852C and A858C, were inhibited by MTSES, indicating that these residues may be located in a pore-lining region.

  18. Incorporation of multi-walled carbon nanotubes in microspheres used as anion exchange resin via suspension polymerization

    NASA Astrophysics Data System (ADS)

    Fathy, Mahmoud; Abdel Moghny, Th.; Awadallah, Ahmed E.; El-Bellihi, Abdel-Hameed A.-A.

    2014-06-01

    Amination of vinylbenzyl chloride-divinylbenzene (VBC-DVB) copolymers is an effective method for preparation of anion-exchange resins. Conventionally, the starting polymer is produced by chloromethylation of a styrene-divinylbenzene copolymer that utilizes chloromethyl methyl ether, a known carcinogen. An alterative approach is to copolymerize vinylbenzyl chloride with divinylbenzene to generate the necessary VBC-DVB. This method provides precise control over the density of the ion-exchange groups. The regiochemistry of the vinylbenzyl chloride methods was realized using solvent-ion exchange groups. These resulting anion-exchange polymers were characterized by a variety of techniques such as analytical titrations, transform infrared spectroscopy and thermal gravimetric analysis. Testing of these copolymers for breakthrough was performed. The results indicate that these anion exchangers have a meaningful increase in thermal stability over commercial anionic exchange beads. Resins containing MWCNTs achieved anion exchange capacity value of 323.6 meq/100 g over than that of copolymer resins and that useful in water desalination or treatment.

  19. Automated hydrophobic interaction chromatography column selection for use in protein purification.

    PubMed

    Murphy, Patrick J M; Stone, Orrin J; Anderson, Michelle E

    2011-09-21

    In contrast to other chromatographic methods for purifying proteins (e.g. gel filtration, affinity, and ion exchange), hydrophobic interaction chromatography (HIC) commonly requires experimental determination (referred to as screening or "scouting") in order to select the most suitable chromatographic medium for purifying a given protein (1). The method presented here describes an automated approach to scouting for an optimal HIC media to be used in protein purification. HIC separates proteins and other biomolecules from a crude lysate based on differences in hydrophobicity. Similar to affinity chromatography (AC) and ion exchange chromatography (IEX), HIC is capable of concentrating the protein of interest as it progresses through the chromatographic process. Proteins best suited for purification by HIC include those with hydrophobic surface regions and able to withstand exposure to salt concentrations in excess of 2 M ammonium sulfate ((NH(4;))(2;)SO(4;)). HIC is often chosen as a purification method for proteins lacking an affinity tag, and thus unsuitable for AC, and when IEX fails to provide adequate purification. Hydrophobic moieties on the protein surface temporarily bind to a nonpolar ligand coupled to an inert, immobile matrix. The interaction between protein and ligand are highly dependent on the salt concentration of the buffer flowing through the chromatography column, with high ionic concentrations strengthening the protein-ligand interaction and making the protein immobile (i.e. bound inside the column) (2). As salt concentrations decrease, the protein-ligand interaction dissipates, the protein again becomes mobile and elutes from the column. Several HIC media are commercially available in pre-packed columns, each containing one of several hydrophobic ligands (e.g. S-butyl, butyl, octyl, and phenyl) cross-linked at varying densities to agarose beads of a specific diameter (3). Automated column scouting allows for an efficient approach for determining

  20. Automated sample preparation facilitated by PhyNexus MEA purification system for oligosaccharide mapping of glycoproteins.

    PubMed

    Prater, Bradley D; Anumula, Kalyan R; Hutchins, Jeff T

    2007-10-15

    A reproducible high-throughput sample cleanup method for fluorescent oligosaccharide mapping of glycoproteins is described. Oligosaccharides are released from glycoproteins using PNGase F and labeled with 2-aminobenzoic acid (anthranilic acid, AA). A PhyNexus MEA system was adapted for automated isolation of the fluorescently labeled oligosaccharides from the reaction mixture prior to mapping by HPLC. The oligosaccharide purification uses a normal-phase polyamide resin (DPA-6S) in custom-made pipette tips. The resin volume, wash, and elution steps involved were optimized to obtain high recovery of oligosaccharides with the least amount of contaminating free fluorescent dye in the shortest amount of time. The automated protocol for sample cleanup eliminated all manual manipulations with a recycle time of 23 min. We have reduced the amount of excess AA by 150-fold, allowing quantitative oligosaccharide mapping from as little as 500 ng digested recombinant immunoglobulin G (rIgG). This low sample requirement allows early selection of a cell line with desired characteristics (e.g., oligosaccharide profile and high specific productivity) for the production of glycoprotein drugs. In addition, the use of Tecan or another robotic platform in conjunction with this method should allow the cleanup of 96 samples in 23 min, a significant decrease in the amount of time currently required to process such a large number of samples.

  1. A rapid method for manual or automated purification of fluorescently labeled nucleic acids for sequencing, genotyping, and microarrays.

    PubMed

    Springer, Amy L; Booth, Lisa R; Braid, Michael D; Houde, Christiane M; Hughes, Karin A; Kaiser, Robert J; Pedrak, Casandra; Spicer, Douglas A; Stolyar, Sergey

    2003-03-01

    Fluorescent dyes provide specific, sensitive, and multiplexed detection of nucleic acids. To maximize sensitivity, fluorescently labeled reaction products (e.g., cycle sequencing or primer extension products) must be purified away from residual dye-labeled precursors. Successful high-throughput analyses require that this purification be reliable, rapid, and amenable to automation. Common methods for purifying reaction products involve several steps and require processes that are not easily automated. Prolinx, Inc. has devel oped RapXtract superparamagnetic separation technology affording rapid and easy-to-perform methods that yield high-quality product and are easily automated. The technology uses superparamagnetic particles that specifically remove unincorporated dye-labeled precursors. These particles are efficiently pelleted in the presence of a magnetic field, making them ideal for purification because of the rapid separations that they allow. RapXtract-purified sequencing reactions yield data with good signal and high Phred quality scores, and they work with various sequencing dye chemistries, including BigDye and near-infrared fluorescence IRDyes. RapXtract technology can also be used to purify dye primer sequencing reactions, primer extension reactions for genotyping analysis, and nucleic acid labeling reactions for microarray hybridization. The ease of use and versatility of RapXtract technology makes it a good choice for manual or automated purification of fluorescently labeled nucleic acids.

  2. Anion exchange selectivity of surfactant modified clinoptilolite-rich tuff for environmental remediation.

    PubMed

    de Gennaro, Bruno; Catalanotti, Lilia; Bowman, Robert S; Mercurio, Mariano

    2014-09-15

    Lately, the functionalization of industrial minerals with high technological properties, such as natural zeolites, is shaping as a promising approach in environmental sphere. In fact, under the specific conditions, the surface functionalization via adsorption of cationic surfactants reverses the surface charge of the mineral, enabling zeolites to simultaneously interact either with organic contaminants or inorganic anions. This aspect allows zeolites to be used in the remediation of contaminated fluids. The present research shed new light on some still not fully understood aspects concerning exchange kinetics such as anion-exchange mechanisms and selectivity of surface modified minerals. For this purpose the mineralogical characterization and the surface properties evaluation (X Ray Powder Diffraction, chemical analysis, thermal analysis, ECEC and AEC) of a clinoptilolite-rich tuff were performed, and the anion exchange isotherms of the sample, modified with hexadecyltrimethylammonium chloride or bromide (HDTMA-Cl/-Br), were determined. Ion-exchange equilibrium data of uni-uni valent reaction were obtained by solutions containing Br(-), Cl(-), NO3(-) or ClO4(-). Liquid phase was analysed via high performance liquid chromatography. Thermodynamic quantities (Ka and ΔG(0)) were determined and compared with the Hofmeister series. The value of the ECEC, calculated in batch conditions, was about 137 mmol/kg, in good agreement with that evaluated in dynamic conditions, while the AEC data were different for the SMNZ-Br and -Cl samples, amounting to 137 and 106 mmol/kg, respectively, thus indicating a different compactness of the bilayer formed in the two cases. Moreover, the anion isotherm results and the mathematical evaluation of the thermodynamic parameters, demonstrated the good affinity of SMNZ-Br towards chloride, nitrate and perchlorate, and of SMNZ-Cl for nitrate and perchlorate, also endorsing the possibility of using the same thermodynamic approach developed to

  3. Diclofenac removal in urine using strong-base anion exchange polymer resins.

    PubMed

    Landry, Kelly A; Boyer, Treavor H

    2013-11-01

    One of the major sources of pharmaceuticals in the environment is wastewater effluent of which human urine contributes the majority of pharmaceuticals. Urine source separation has the potential to isolate pharmaceuticals at a higher concentration for efficient removal as well as produce a nutrient byproduct. This research investigated the efficacy of using strong-base anion exchange polymer resins to remove the widely detected and abundant pharmaceutical, diclofenac, from synthetic human urine under fresh and ureolyzed conditions. The majority of experiments were conducted using a strong-base, macroporous, polystyrene resin (Purolite A520E). Ion-exchange followed a two-step removal rate with rapid removal in 1 h and equilibrium removal in 24 h. Diclofenac removal was >90% at a resin dose of 8 mL/L in both fresh and ureolyzed urine. Sorption of diclofenac onto A520E resin was concurrent with desorption of an equivalent amount of chloride, which indicates the ion-exchange mechanism is occurring. The presence of competing ions such as phosphate and citrate did not significantly impact diclofenac removal. Comparisons of three polystyrene resins (A520E, Dowex 22, Dowex Marathon 11) as well as one polyacrylic resin (IRA958) were conducted to determine the major interactions between anion exchange resin and diclofenac. The results showed that polystyrene resins provide the highest level of diclofenac removal due to electrostatic interactions between quaternary ammonium functional groups of resin and carboxylic acid of diclofenac and non-electrostatic interactions between resin matrix and benzene rings of diclofenac. Diclofenac was effectively desorbed from A520E resin using a regeneration solution that contained 4.5% (m/m) NaCl in an equal-volume mixture of methanol and water. The greater regeneration efficiency of the NaCl/methanol-water mixture over the aqueous NaCl solution supports the importance of non-electrostatic interactions between resin matrix and benzene rings

  4. Automated high-throughput protein purification using an ÄKTApurifier and a CETAC autosampler.

    PubMed

    Yoo, Daniel; Provchy, Justin; Park, Cynthia; Schulz, Craig; Walker, Kenneth

    2014-05-30

    As the pace of drug discovery accelerates there is an increased focus on screening larger numbers of protein therapeutic candidates to identify those that are functionally superior and to assess manufacturability earlier in the process. Although there have been advances toward high throughput (HT) cloning and expression, protein purification is still an area where improvements can be made to conventional techniques. Current methodologies for purification often involve a tradeoff between HT automation or capacity and quality. We present an ÄKTA combined with an autosampler, the ÄKTA-AS, which has the capability of purifying up to 240 samples in two chromatographic dimensions without the need for user intervention. The ÄKTA-AS has been shown to be reliable with sample volumes between 0.5 mL and 100 mL, and the innovative use of a uniquely configured loading valve ensures reliability by efficiently removing air from the system as well as preventing sample cross contamination. Incorporation of a sample pump flush minimizes sample loss and enables recoveries ranging from the low tens of micrograms to milligram quantities of protein. In addition, when used in an affinity capture-buffer exchange format the final samples are formulated in a buffer compatible with most assays without requirement of additional downstream processing. The system is designed to capture samples in 96-well microplate format allowing for seamless integration of downstream HT analytic processes such as microfluidic or HPLC analysis. Most notably, there is minimal operator intervention to operate this system, thereby increasing efficiency, sample consistency and reducing the risk of human error.

  5. Anion-exchange separation of Pt and Pd using perchloric and hydrochloric acid solutions

    USGS Publications Warehouse

    Petrie, R.K.; Morgan, J.W.

    1982-01-01

    On Biorad Ag-1X8 anion-exchange resin (200-400 mesh), Pd and Pt may be separated from one another by elution with 0.2M HClO4, and 5M HClO4, respectively. If present, Au may be retained by making the elutriants 0.003M in HCl. Alternatively, reduction by H2SO3 enables elution of Pt2+ with 6M HCl before recovery of Pd2+ with 0.2M HClO4??Ir4+ is reduced to Ir3+ by H2SO3 and may be eluted ahead of Pt2+ by 2M HCl. ?? 1982 Akade??miai Kiado??.

  6. Fouling of anion exchange resin by fluorescence analysis in advanced treatment of municipal wastewaters.

    PubMed

    Li, Haibo; Li, Aimin; Shuang, Chendong; Zhou, Qing; Li, Wentao

    2014-12-01

    The application of anion exchange resins (AERs) has been limited by the critical problem of resin fouling, which increases the volume of the desorption concentrate and decreases treatment efficiency. To date, resin fouling has not been well studied and is poorly understood compared to membrane fouling. To reflect the resin fouling level, a resin fouling index (RFI) was established in this work according to the decrease of DOC removal after regeneration of the resin for the advanced treatment of municipal wastewater. Comparing the linear fitting results between the RFI and the fluorescence intensity indicated that the resin fouling was related to the protein-like substances with fluorescence peak T in the region of excitation wavelength <250 nm and emission wavelength <380 nm. Using their fluorescent characteristics as a label, the protein-like substances causing the fouling were further identified as hydrophilic components with molecular weights greater than 6500 Da.

  7. Magnetic graphitic carbon nitride anion exchanger for specific enrichment of phosphopeptides.

    PubMed

    Zhu, Gang-Tian; He, Xiao-Mei; Chen, Xi; Hussain, Dilshad; Ding, Jun; Feng, Yu-Qi

    2016-03-11

    Anion-exchange chromatography (AEX) is one of the chromatography-based methods effectively being used for phosphopeptide enrichment. However, the development of AEX materials with high specificity toward phosphopeptides is still less explored as compared to immobilized metal affinity chromatography (IMAC) or metal oxide affinity chromatography (MOAC). In this work, magnetic graphitic carbon nitride (MCN) was successfully prepared and introduced as a promising AEX candidate for phosphopeptide enrichment. Due to the extremely abundant content of nitrogen with basic functionality on the surface, this material kept excellent retention for phosphopeptides at pH as low as 1.8. Benefiting from the large binding capacity at such low pH, MCN showed remarkable specificity to capture phosphopeptides from tryptic digests of standard protein mixtures as well as nonfat milk and human serum. In addition, MCN was also applied to selective enrichment of phosphopeptides from the tryptic digests of rat brain lysate and 2576 unique phosphopeptides were successfully identified.

  8. Thermally Cross-Linked Anion Exchange Membranes from Solvent Processable Isoprene Containing Ionomers

    SciTech Connect

    Tsai, Tsung-Han; Ertem, S. Piril; Maes, Ashley M.; Seifert, Soenke; Herring, Andrew M; Coughlin, E. Bryan

    2015-01-28

    Random copolymers of isoprene and 4-vinylbenzyl chloride (VBCl) with varying compositions were synthesized via nitroxide-mediated polymerization. Subsequent quaternization afforded solvent processable and cross-linkable ionomers with a wide range of ion exchange capacities (IECs). Solution cast membranes were thermally cross-linked to form anion exchange membranes. Cross-linking was achieved by taking advantage of the unsaturations on the polyisoprene backbone, without added cross-linkers. A strong correlation was found between water uptake and ion conductivity of the membranes: conductivities of the membranes with IECs beyond a critical value were found to be constant related to their high water absorption. Environmentally controlled small-angle X-ray scattering experiments revealed a correlation between the average distance between ionic clusters and the ion conductivity, indicating that a well-connected network of ion clusters is necessary for efficient ion conduction and high ion conductivity.

  9. Synthesis of Composition Tunable and Highly Luminescent Cesium Lead Halide Nanowires through Anion-Exchange Reactions.

    PubMed

    Zhang, Dandan; Yang, Yiming; Bekenstein, Yehonadav; Yu, Yi; Gibson, Natalie A; Wong, Andrew B; Eaton, Samuel W; Kornienko, Nikolay; Kong, Qiao; Lai, Minliang; Alivisatos, A Paul; Leone, Stephen R; Yang, Peidong

    2016-06-15

    Here, we demonstrate the successful synthesis of brightly emitting colloidal cesium lead halide (CsPbX3, X = Cl, Br, I) nanowires (NWs) with uniform diameters and tunable compositions. By using highly monodisperse CsPbBr3 NWs as templates, the NW composition can be independently controlled through anion-exchange reactions. CsPbX3 alloy NWs with a wide range of alloy compositions can be achieved with well-preserved morphology and crystal structure. The NWs are highly luminescent with photoluminescence quantum yields (PLQY) ranging from 20% to 80%. The bright photoluminescence can be tuned over nearly the entire visible spectrum. The high PLQYs together with charge transport measurements exemplify the efficient alloying of the anionic sublattice in a one-dimensional CsPbX3 system. The wires increased functionality in the form of fast photoresponse rates and the low defect density suggest CsPbX3 NWs as prospective materials for optoelectronic applications.

  10. Anion exchange kinetics of nanodimensional layered metal hydroxides: use of isoconversional analysis.

    PubMed

    Majoni, Stephen; Hossenlopp, Jeanne M

    2010-12-16

    Anion exchange reactions of nanodimensional layered metal hydroxide compounds are utilized to create materials with targeted physical and chemical properties and also as a means for controlled release of intercalated anions. The kinetics of this important class of reaction are generally characterized by model-based approaches. In this work, a different approach based on isothermal, isoconversional analysis was utilized to determine effective activation energies with respect to extent of reaction. Two different layered metal hydroxide materials were chosen for reaction with chloride anions, using a temperature range of 30-60 °C. The concentrations of anions released into solution and the changes in polycrystalline solid phases were evaluated using model-based (Avrami-Erofe'ev nucleation-growth model) and model-free (integral isoconversional) methods. The results demonstrate the utility of the isoconversional approach for identifying when fitting to a single model is not appropriate, particularly for characterizing the temperature dependence of the reaction kinetics.

  11. Regeneration of strong-base anion-exchange resins by sequential chemical displacement

    DOEpatents

    Brown, Gilbert M.; Gu, Baohua; Moyer, Bruce A.; Bonnesen, Peter V.

    2002-01-01

    A method for regenerating strong-base anion exchange resins utilizing a sequential chemical displacement technique with new regenerant formulation. The new first regenerant solution is composed of a mixture of ferric chloride, a water-miscible organic solvent, hydrochloric acid, and water in which tetrachloroferrate anion is formed and used to displace the target anions on the resin. The second regenerant is composed of a dilute hydrochloric acid and is used to decompose tetrachloroferrate and elute ferric ions, thereby regenerating the resin. Alternative chemical displacement methods include: (1) displacement of target anions with fluoroborate followed by nitrate or salicylate and (2) displacement of target anions with salicylate followed by dilute hydrochloric acid. The methodology offers an improved regeneration efficiency, recovery, and waste minimization over the conventional displacement technique using sodium chloride (or a brine) or alkali metal hydroxide.

  12. Hydrothermal carbon nanosphere-based agglomerated anion exchanger for ion chromatography.

    PubMed

    Zhao, Qiming; Wu, Shuchao; Zhang, Kai; Lou, Chaoyan; Zhang, Peiming; Zhu, Yan

    2016-10-14

    This work reports the application of hydrothermal carbon nanospheres (HCNSs) as stationary phases in ion chromatography. HCNSs were facilely quaternized through polycondensation of methylamine and 1,4-butanediol diglycidyl ether. The quaternization was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Owing to the electrostatic interaction, quaternized HCNSs were equably attached onto the surface of sulfonated polystyrene-divinylbenzene (PS-DVB) beads to construct the anion exchangers. The aggregation was verified by scanning electron microscopy and elemental analysis. Common anions, aliphatic monocarboxylic acids, polarizable anions, and aromatic acids were well separated on the stationary phases with good stability and symmetry. The prepared column was further applied to detect phosphate content in Cola drink samples. The limit of detection (S/N=3) was 0.09mg/L, and the relative standard deviation (n=10) of retention time was 0.31%. The average recovery was 99.58%.

  13. Mg/Al double-metal hydroxide regeneration of anion exchange resin by electric field intensification.

    PubMed

    Wang, Ying; Li, Zhun; Li, Yansheng; Liu, Zhigang

    2017-03-01

    Fouled anion exchange resins were regenerated by electric field intensification of Mg/Al double-metal hydroxides. Regenerative experiments were performed with varying voltages (10-30 V) and dosages of Mg/Al hydroxides (0.045-0.135 mol and 0.015-0.045 mol, respectively) for 1-5 h. Optimal results were obtained under the following regenerative conditions: 20 V, 4 h, and 0.09/0.03 mol of Mg/Al hydroxides. The maximum regenerative capacity of resins was increased to 41.07%. The regenerative mechanism was presented by Fourier-transform infrared spectrum of resins and Mg/Al hydroxides, and the regenerative degree was analyzed with respect to conductivity, pH value, and electric current. Mg/Al hydroxides were also recycled after the regeneration. This method was proven to be cost-effective and environmentally friendly.

  14. Chromatographic separation of vanadium, tungsten and molybdenum with a liquid anion-exchanger.

    PubMed

    Fritz, J S; Topping, J J

    1971-09-01

    In acidic solution only molybdenum(VI), tungsten(VI), vanadium(V), niobium(V) and tantalum(V) form stable, anionic complexes with dilute hydrogen peroxide. This fact has been used in developing an analytical method of separating molybdenum(VI), tungsten(VI) and vanadium(V) from other metal ions and from each other. Preliminary investigations using reversed-phase paper chromatography and solvent extraction led to a reversed-phase column Chromatographic separation technique. These metal-peroxy anions are retained by a column containing a liquid anion-exchanger (General Mills Aliquat 336) in a solid support. Then molybdenum(VI), tungsten(VI) and vanadium(V) are selectively eluted with aqueous solutions containing dilute hydrogen peroxide and varying concentrations of sulphuric acid.

  15. Water uptake, ionic conductivity and swelling properties of anion-exchange membrane

    NASA Astrophysics Data System (ADS)

    Duan, Qiongjuan; Ge, Shanhai; Wang, Chao-Yang

    2013-12-01

    Water uptake, ionic conductivity and dimensional change of the anion-exchange membrane made by Tokuyama Corporation (A201 membrane) are investigated at different temperatures and water activities. Specifically, the amount of water taken up by membranes exposed to water vapor and membranes soaked in liquid water is determined. The water uptake of the A201 membrane increases with water content as well as temperature. In addition, water sorption data shows Schroeder's paradox for the AEMs investigated. The swelling properties of the A201 membrane exhibit improved dimensional stability compared with Nafion membrane. Water sorption of the A201 membrane occurs with a substantial negative excess volume of mixing. The threshold value of hydrophilic fraction in the A201 membrane for ionic conductivity is around 0.34, above which, the conductivity begins to rise quickly. This indicates that a change in the connectivity of the hydrophilic domains occurs when hydrophilic fraction approaches 0.34.

  16. NASA Li/CF(x) cell problem analysis: Anion exchange chromatography analysis

    NASA Astrophysics Data System (ADS)

    Bytella, Joseph

    1991-05-01

    An analysis was made of wiper samples used to wipe down lithium/chlorine fluorine battery components and production equipment. These components and equipment were potentially exposed to thionyl chloride vapors. In the presence of moisture, thionyl chloride decomposes to sulfur dioxide and hydrogen chloride. The wiper samples were analyzed for soluble chlorides and fluorides by anion exchange chromatography. During the examination of the test chromatographs, fluoride contamination was discovered in wiper samples from the test equipment. An analytical method to determine fluoride was developed. The first 3 extracts from the potentially exposed and clean wiper samples were tested, and the total fluoride from both groups determined. A comparison of the results from both groups was made to determine the extent of fluoride contamination.

  17. Controllable Synthesis of Mn6+ Doped Nanoparticles by a Facile Anion Exchange Method

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaowen; Li, Yang; Liao, Chenxing; Chen, Zhi; Qiu, Jianrong

    2017-01-01

    Fluorescence imaging in the second near-infrared window (NIR-II, 1000-1400 nm) is attracting extensive attention. Mn6+ doped BaSO4 with broadband emission from 900 nm to 1400 nm is emerging as a new class of NIR phosphor for fluorescence imaging. Manganese has diverse valence states, thus it is difficult to prevent valence change of Mn6+ during traditional synthesis process. In this work, BaSO4:Mn6+ nanoparticles with uniform size and morphology were first successfully prepared through a fast liquid-solid solution route at room temperature. The nanoparticles exhibit broadband NIR emission from Mn6+ when excited by 808 nm lasers. This convenient strategy, based on an efficient anion exchange reaction, is proved effective for synthesizing nano-sized materials. The results reveal that our strategy has great potential in fabricating special valence state ion doped nanomaterials.

  18. Chemical treatment of plutonium with hydrogen peroxide before nitrate anion exchange processing. [Reduction to (IV)

    SciTech Connect

    Marsh, S.F.; Gallegos, T.D.

    1987-05-01

    The major aqueous process used to recover and purify plutonium at the Los Alamos Plutonium Facility is anion exchange in nitric acid. This process is highly selective for plutonium; however, all plutonium must be as Pu(IV) to form the strongly sorbed anionic nitrato complex. The previous ''full-reduction treatment'' used at Los Alamos to obtain Pu(IV) results in a three- to fourfold increase in the feed solution volume and the introduction of kilogram quantities of extraneous salts immediately before a process whose function is to remove such impurities. That treatment has been successfully replaced by a single reagent, hydrogen peroxide, which converts all plutonium to Pu(IV), minimally increases the feed volume, and introduces no residual impurities. Safety aspects of this revised chemical treatment are addressed.

  19. NASA Li/CF(x) cell problem analysis: Anion exchange chromatography analysis

    NASA Technical Reports Server (NTRS)

    Bytella, Joseph

    1991-01-01

    An analysis was made of wiper samples used to wipe down lithium/chlorine fluorine battery components and production equipment. These components and equipment were potentially exposed to thionyl chloride vapors. In the presence of moisture, thionyl chloride decomposes to sulfur dioxide and hydrogen chloride. The wiper samples were analyzed for soluble chlorides and fluorides by anion exchange chromatography. During the examination of the test chromatographs, fluoride contamination was discovered in wiper samples from the test equipment. An analytical method to determine fluoride was developed. The first 3 extracts from the potentially exposed and clean wiper samples were tested, and the total fluoride from both groups determined. A comparison of the results from both groups was made to determine the extent of fluoride contamination.

  20. Enhancement of anion-exchange chromatography of DNA using compaction agents

    NASA Technical Reports Server (NTRS)

    Murphy, Jason C.; Fox, George E.; Willson, Richard C.

    2003-01-01

    The use of adsorptive chromatography for preparative nucleic acid separations is often limited by low capacity. The possibility that the adsorbent surface area sterically accessible to nucleic acid molecules could be increased by reducing their radius of gyration with compaction agents has been investigated. The equilibrium adsorption capacity of Q Sepharose anion-exchange matrix for plasmid DNA at 600 mM NaCl was enhanced by up to ca. 40% in the presence of 2.5 mM spermine. In addition, compaction agent selectivity has been demonstrated. Spermine, for example, enhances the adsorption of both plasmid and genomic DNA, spermidine enhances binding only of plasmid, and hexamine cobalt enhances only the binding of genomic DNA. Compaction may be generally useful for enhancing adsorptive separations of nucleic acids.

  1. Perchlorate Selectivity of Anion Exchange Resins as Evaluated Using Ion-Selective Electrodes.

    PubMed

    Yamamoto, Kenji; Mitsuda, Shin'ya; Ohtake, Naomi; Murashige, Natsuki; Ohmuro, Satoshi; Yuchi, Akio

    2017-01-01

    The selectivity coefficients reported for perchlorate of the high selectivity on anion exchange resins (AXRs) have not been consistent with one another. Possible errors by the unique use of four parameters (concentrations of two anions in two phases) were experimentally verified. The concentrations of perchlorate buffered at low levels (10(-6) - 10(-4) mol L(-1)) by two forms of AXRs were successfully determined by potentiometry with a perchlorate ion-selective electrode. This gave reasonable coefficients. The coefficients for perchlorate on several AXRs were independent of the relative exchange (RE), in contrast to the previous reports. On the other hand, the coefficients for fluoride of the low selectivity that were examined for comparison decreased with an increase in RE, and the dependency was more remarkable for the resins of large exchange capacity.

  2. Kinetics of sorption of niobium ions by anion-exchangers from mixed chloride-fluoride solutions

    SciTech Connect

    Rychkov, V.N.; Pakholkov, V.S.; Kuznetsova, L.D.

    1987-08-10

    The authors showed earlier on the basis of experimental and calculated data obtained in studies of ion-exchange equilibrium that the sorbability and composition of sorbed niobium ions are determined by the content of hydrofluoric acid in mixed chloride-fluoride solutions. Variation of the ionic state of niobium in these solutions should also influence the rate of ion exchange. In this communication they examine the results of a study of the kinetics of exchange of niobium ions on AV-17 x 8, EDE-10P, and AN-2F anion-exchange resins in fluoride-containing solutions. Kinetic curves for sorption of niobium ions and the results of their evaluation are presented.

  3. Multigram group separation of actinide and lanthanide elements by LiCl-based anion exchange

    SciTech Connect

    Collins, E.D.; Benker, D.E.; Chattin, F.R.; Orr, P.B.; Ross, R.G.

    1980-01-01

    The laboratory-scale LiCl AIX process has been successfully adapted to the multigram scale and has been used effectively in transuranium element production campaigns to separate the lanthanide fission products from the transplutonium actinides and to partition americium and curium from the heavier elements. Corrosion of the tantalum and glass equipment has been negligible. Although radiolytic gas generation has not caused a problem, radiation exposure of the Dowex 1-X10 anion exchange resin does occur significantly. However, the 1.3-L resin bed can be used successfully to process up to 3 batches, each containing 19 g of /sup 244/Cm (54 W of decay heat). The chromatographic elution process is controlled by use of an alpha detector in the column effluent line and by periodic measurement of the neutron profile of the column. The development and use of feed pretreatment and operating methods has enabled effective and dependable operation.

  4. Evaluating of arsenic(V) removal from water by weak-base anion exchange adsorbents.

    PubMed

    Awual, M Rabiul; Hossain, M Amran; Shenashen, M A; Yaita, Tsuyoshi; Suzuki, Shinichi; Jyo, Akinori

    2013-01-01

    Arsenic contamination of groundwater has been called the largest mass poisoning calamity in human history and creates severe health problems. The effective adsorbents are imperative in response to the widespread removal of toxic arsenic exposure through drinking water. Evaluation of arsenic(V) removal from water by weak-base anion exchange adsorbents was studied in this paper, aiming at the determination of the effects of pH, competing anions, and feed flow rates to improvement on remediation. Two types of weak-base adsorbents were used to evaluate arsenic(V) removal efficiency both in batch and column approaches. Anion selectivity was determined by both adsorbents in batch method as equilibrium As(V) adsorption capacities. Column studies were performed in fixed-bed experiments using both adsorbent packed columns, and kinetic performance was dependent on the feed flow rate and competing anions. The weak-base adsorbents clarified that these are selective to arsenic(V) over competition of chloride, nitrate, and sulfate anions. The solution pH played an important role in arsenic(V) removal, and a higher pH can cause lower adsorption capacities. A low concentration level of arsenic(V) was also removed by these adsorbents even at a high flow rate of 250-350 h(-1). Adsorbed arsenic(V) was quantitatively eluted with 1 M HCl acid and regenerated into hydrochloride form simultaneously for the next adsorption operation after rinsing with water. The weak-base anion exchange adsorbents are to be an effective means to remove arsenic(V) from drinking water. The fast adsorption rate and the excellent adsorption capacity in the neutral pH range will render this removal technique attractive in practical use in chemical industry.

  5. Sulfate transport mediated by the mammalian anion exchangers in reconstituted proteoliposomes.

    PubMed

    Sekler, I; Lo, R S; Mastrocola, T; Kopito, R R

    1995-05-12

    The kinetic properties of sulfate transport mediated by the anion exchangers AE1 and AE2 have been examined. Microsomes isolated from HEK cells transiently overexpressing either protein were reconstituted in unilamellar, 200-600-nm diameter proteoliposomes. Transport mediated by the exchangers was monitored by loading the reconstituted proteoliposomes with the slowly transportable anion SO4(2-) using [35S]SO4(2-) as a tracer and performing [35S]SO4(2-)/SO4(2-) exchange. The following data suggest that AE1 and AE2 have been functionally reconstituted: (i) the rate of SO4(2-) transport in AE1 and AE2 containing proteoliposomes was 10-20 times higher than in proteoliposomes derived from control microsomes; (ii) the transport of SO4(2-) was strongly dependent on the presence of a trans anion; and (iii) the anion exchanger inhibitors, 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) and 4,4'-dinitrostilbene-2,2'-di-sulfonate (DIDS) totally abolished SO4(2-) transport. furthermore, DIDS inhibits SO4(2-) transport only when occluded inside the vesicles, indicating a uniform, asymmetrical, inside-out orientation of the reconstituted exchangers. The Ki values of the stilbene disulfonate compound DNDS were 2.5 and 4 microM for AE1 and AE2, respectively, suggesting that the two exchangers possess similar high affinity sites for stilbene compounds. Both AE1 and AE2 showed the same steep pH dependence of sulfate transport, which was maximal at pH 5.5 and reduced to less than 10% (of the value at pH 5.5) at pH 8.5, suggesting that an acidic residue shared by AE1 and AE2 participates in the pH regulation of sulfate transport.

  6. Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell Membranes

    NASA Technical Reports Server (NTRS)

    Narayan, Sri R.; Yen, Shiao-Ping S.; Reddy, Prakash V.; Nair, Nanditha

    2012-01-01

    Polymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrene-based quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells. Imidazolium salts are known to be electrochemically stable over wide potential ranges. By controlling the relative ratio of imidazolium groups in polystyrene-imidazolium salts, their physiochemical properties could be modulated. Alkaline anion exchange membranes based on polystyrene-imidazolium hydroxide materials have been developed. The first step was to synthesize the poly(styrene-co-(1-((4-vinyl)methyl)-3- methylimidazolium) chloride through a free-radical polymerization. Casting of this material followed by in situ treatment of the membranes with sodium hydroxide solutions provided the corresponding hydroxide salts. Various ratios of the monomers 4-chloromoethylvinylbenzine (CMVB) and vinylbenzine (VB) provided various compositions of the polymer. The preferred material, due to the relative ease of casting the film, and its relatively low hygroscopic nature, was a 2:1 ratio of CMVB to VB. Testing confirmed that at room temperature, the new membranes outperformed commercially available membranes by a large margin. With fuel cells now in use at NASA and in transportation, and with defense potential, any improvement to fuel cell efficiency is a significant development.

  7. Possibility of separating toxins from bacteria associated with sudden infant death syndrome using anion exchange chromatography.

    PubMed Central

    Drucker, D B; Aluyi, H A; Morris, J A; Telford, D R; Oppenheim, B A; Crawley, B A

    1992-01-01

    AIMS: To develop techniques for the characterisation of toxins elaborated by a strain of Escherichia coli associated with sudden infant death syndrome (SIDS). METHODS: E coli SIDS 04, isolated from the nasopharynx of a case of SIDS, was studied. Cell-free toxin preparations were standardised, their protein measured, and analytical separation of proteins achieved using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Acetone precipitation of proteins was required prior to Coomassie blue staining of bands. Preparative separation was achieved on an anion exchange column using a programmed concentration gradient of NaCl in TRIS buffer. Fractions were tested individually or pooled for presence of lethal toxin including endotoxin. Lethal toxin was detected with the chick embryo test system. Endotoxin was measured using a chromogenic modification of the Limulus amoebocyte assay. RESULTS: Twenty one peaks were detected by chromatography. Ten individual, or pooled, fractions were assayed for endotoxin which ranged from 27-33 pg/ml. Much greater variation was found when the same fractions were assayed in chick embryos. E coli fractions varied considerably in lethal toxicity, from 0/10 to 10/10 chick embryos killed/tested. Certain E coli fractions tested individually (lethality four out of 10 to eight out of 10) proved more lethal (10 out of 10) if pooled prior to testing. CONCLUSIONS: In E coli infection associated with SIDS relatively low concentrations of extracellular protein are lethally toxigenic for the chick embryo model of SIDS. These proteins can be separated analytically by SDS-PAGE and preparatively by anion exchange chromatography. Toxicity of individual fractions is not correlated with endotoxin concentrations in samples tested. PMID:1401212

  8. Design and performance evaluation of a microfluidic ion-suppression module for anion-exchange chromatography.

    PubMed

    Wouters, Sam; Wouters, Bert; Jespers, Sander; Desmet, Gert; Eghbali, Hamed; Bruggink, Cees; Eeltink, Sebastiaan

    2014-08-15

    A microfluidic membrane suppressor has been constructed to suppress ions of alkaline mobile-phases via an acid-base reaction across a sulfonated poly(tetrafluoroethylene)-based membrane and was evaluated for anion-exchange separations using conductivity detection. The membrane was clamped between two chip substrates, accommodating rectangular microchannels for the eluent and regenerant flow, respectively. Additionally, a clamp-on chip holder has been constructed which allows the alignment and stacking of different chip modules. The response and efficacy of the microfluidic chip suppressor was assessed for a wide range of eluent (KOH) concentrations, using 127 and 183μm thick membranes, while optimizing the flow rate and concentration of the regenerant solution (H2SO4). The optimal operating eluent flow rate was determined at 5μL/min, corresponding to the optimal van-Deemter flow velocity of commercially-available column technology, i.e. a 0.4mm i.d.×250mm long column packed with 7.5μm anion-exchange particles. When equilibrated at 10mM KOH, a 99% decrease in conductivity signal could be obtained within 5min when applying 10mM H2SO4 regenerant at 75μL/min. A background signal as low as 1.2μS/cm was obtained, which equals the performance of a commercially-available electrolytic hollow-fiber suppressor. When increasing the temperature of the membrane suppressor from 15 to 20°C, ion suppression was significantly improved allowing the application of 75mM KOH. The applicability of the chip suppressor has been demonstrated with an isocratic baseline separation of a mixture of seven inorganic ions, yielding plate numbers between 5300 and 10,600 and with a gradient separation of a complex ion mixture.

  9. Removal of chloride ion from aqueous solution by ZnAl-NO(3) layered double hydroxides as anion-exchanger.

    PubMed

    Lv, Liang; Sun, Peide; Gu, Zhengyu; Du, Hangeng; Pang, Xiangjun; Tao, Xiaohong; Xu, Rufeng; Xu, Lili

    2009-01-30

    The layered double hydroxides (LDHs) containing nitrate as the interlayer anion has a high anion-exchange capacity in the presence of appropriate anions. In the light of this, ZnAl-NO(3) LDHs have been employed to remove chloride ion from aqueous solution in a batch mode. The influences of conditions for chloride ion uptake, including dosage of LDHs, pH of aqueous solution, and temperature on anion-exchange have been investigated, respectively. The thermodynamic parameters including Gibbs free energy (DeltaG(0)), standard enthalpy change (DeltaH(0)), and standard entropy change (DeltaS(0)) for the process were calculated using the Langmuir constants. It was found from kinetics test that the pseudo-second order kinetics model could be used to well describe the uptake process. An E(a) value of 10.27 kJ/mol provides evidence the anion-exchange process. The explanation of anion-exchange phenomenon has also been supported by X-ray diffraction and FT-IR spectra.

  10. Mechanism of sorption sulpho-derivative organic chelating agents on strong base anion exchanger Amberlite IRA-402 by FT-IR/PAS and DRS methods

    NASA Astrophysics Data System (ADS)

    Wronski, G.; Pasieczna-Patkowska, S.; Hubicki, Z.

    2008-02-01

    In the paper, strong base anion exchanger Amberlite IRA-402 was modified by using sulpho-derivative organic chelating agents as: Brilliant Yellow, Xylenol Orange, Bromophenyl Blue. The investigations exhibited, that anion exchanger Amberlite IRA-402 is modified very simply by organic chelating agents (working capacity 0.25 0.5 g/cm3).

  11. Borate-aided anion exchange high-performance liquid chromatography of uridine diphosphate-sugars in brain, heart, adipose and liver tissues.

    PubMed

    Oikari, Sanna; Venäläinen, Tuula; Tammi, Markku

    2014-01-03

    In this paper we describe a method optimized for the purification of uridine diphosphate (UDP)-sugars from liver, adipose tissue, brain, and heart, with highly reproducible up to 85% recoveries. Rapid tissue homogenization in cold ethanol, lipid removal by butanol extraction, and purification with a graphitized carbon column resulted in isolation of picomolar quantities of the UDP-sugars from 10 to 30mg of tissue. The UDP-sugars were baseline separated from each other, and from all major nucleotides using a CarboPac PA1 anion exchange column eluted with a gradient of acetate and borate buffers. The extraction and purification protocol produced samples with few unidentified peaks. UDP-N-acetylglucosamine was a dominant UDP-sugar in all the rat tissues studied. However, brain and adipose tissue showed high UDP-glucose levels, equal to that of UDP-N-acetylglucosamine. The UDP-N-acetylglucosamine showed 2.3-2.7 times higher levels than UDP-N-acetylgalactosamine in all tissues, and about the same ratio was found between UDP-glucose and UDP-galactose in adipose tissue and brain (2.6 and 2.8, respectively). Interestingly, the UDP-glucose/UDP-galactose ratio was markedly lower in liver (1.1) and heart (1.7). The UDP-N-acetylglucosamine/UDP-glucuronic acid ratio was also constant, between 9.7 and 7.7, except in liver with the ratio as low as 1.8. The distinct UDP-glucose/galactose ratio, and the abundance of UDP-glucuronic acid may reflect the specific role of liver in glycogen synthesis, and metabolism of hormones and xenobiotics, respectively, using these UDP-sugars as substrates.

  12. ANIONIC EXCHANGE PROCESS FOR THE RECOVERY OF URANIUM AND VANADIUM FROM CARBONATE SOLUTIONS

    DOEpatents

    Bailes, R.H.; Ellis, D.A.; Long, R.S.

    1958-12-16

    Uranium and vanadium can be economically purified and recovered from non- salt roast carbonate leach liquors by adsorption on a strongly basic anionic exchange resin and subsequent selective elution by one of three alternative methods. Method 1 comprises selectively eluting uranium from the resin with an ammonium sulfate solution followed by eluting vanadium from the resin with either 5 M NaCl, saturated (NH/sub 4/)/sub 2/CO/sub 3/, saturated NaHCO/sub 3/, 1 M NaOH, or saturated S0/sub 2/ solutions. Method II comprises selectively eluting vanadium from the resin with either concentrated NaCl or S0/sub 2/ solutions subsequent to pretreatment of the column with either S0/sub 2/ gas, 1 N HCl, or 0.1 N H/sub 2/8O/sub 4/ followed by eluting uranium from the resin with solutions containing 0.9 M NH/sub 4/Cl or NaCl and 0.1 Cl. Method III comprises flowing the carbonate leac solutlon through a first column of a strongly basic anlonlc exchange resin untll vanadium breakthrough occurs, so that the effluent solution is enriched ln uranium content and the vanadium is chiefly retalned by the resln, absorbing the uranlum from the enriched effluent solution on a second column of a strongly basic anionic exchange resin, pretreating the first column with either 0.1 N HCl, 0.1 H/sub 2/SO/sub 4/, C0/sub 2/ gas, or ammonium sulfate, selectively eluting the vanadlum from the column with saturated S0/sub 2/ solution, pretreatlng the second column with either 0.1 N HCl or S0/sub 2/ gas, selectively eluting residual vanadium from the column with saturated S0/sub 2/ solution, and then eluting the uranium from the column with either 0.1 N HCl and 1 N NaCl orO.l N HCl and 1 N NH/sub 4/Cl.

  13. Grafting glycidyl methacrylate to Sepharose gel for fabricating high-capacity protein anion exchangers.

    PubMed

    Wang, Qianqian; Yu, Linling; Sun, Yan

    2016-04-22

    To develop ion exchangers of high protein adsorption capacity, we have herein introduced atom transfer radical polymerization (ATRP) method to graft glycidyl methacrylate (GMA) onto Sepharose FF gel. GMA-grafted Sepharose FF resins of four grafting densities and different grafting chain lengths were obtained by adjusting reaction conditions. The epoxy groups on the grafted chains were functionalized by modification with diethylamine (DEA), leading to the fabrication of Sepharose-based anion exchangers of 14 different grafting densities and/or grafting chain lengths. The resins were first characterized for the effects of grafting density, chain length and ionic strength on pore sizes by inverse size exclusion chromatography. Then, the resins were evaluated by adsorption equilibria of bovine serum albumin (BSA) as a function of ionic capacity (IC) (chain length) at individual grafting densities. It was observed that at each grafting density there was a specific IC value (chain length) that offered the maximum equilibrium capacity. Of the resins with maximum values at individual grafting densities, the resin of the second grafting density with an IC value of 330 mmol/L (denoted as FF-Br2-pG-D330) showed the highest capacity, 264 mg/mL, about two times higher than that of the traditional ungrafted resin Q Sepharose FF (137 mg/mL). This resin also showed the most favorable uptake kinetics among the resins of similar IC values but different grafting densities, or of the same grafting density but different IC values. Effects of ionic strength showed that the capacities of FF-Br2-pG-D330 were much higher than Q Sepharose FF at a wide range of NaCl concentrations (0-200 mmol/L), and the uptake rates of the two resins were similar in the ionic strength range. Therefore, the dynamic binding capacity values of BSA on FF-Br2-pG-D330 were much higher than Q Sepharose FF as demonstrated at different residence times and ionic strengths. Taken together, the research has proved the

  14. Effect of Oxalate on the Recycle of Neptunium Filtrate Solution by Anion Exchange

    SciTech Connect

    Kyser, E

    2004-11-18

    A series of laboratory column runs has been performed that demonstrates the recovery of neptunium (Np) containing up to 0.05 M oxalate. Np losses were generally less than one percent to the raffinate for feed solutions that contained 2 to 10 g Np/L. Up to 16 percent Np losses were observed with lower Np feed concentrations, but those losses were attributed to the shortened residence times rather than the higher oxalate to Np ratios. Losses in the plant are expected to be significantly less due to the lower cross-section flowrate possible with existing plant pumps. Elimination of the permanganate treatment of filtrates appears to be reasonable since the amount of Np in those filtrates does not appear to be practical to recover. Combination of untreated filtrates with other actinide rich solutions is not advisable as precipitation problems are likely. If untreated filtrates are kept segregated from other actinide rich streams, the recovery of the remaining Np is probably still possible, but could be limited due to the excessively high oxalate to Np ratio. The persistence of hydrazine/hydrazoic acid in filtrate solutions dictates that the nitrite treatment be retained to eliminate those species from the filtrates prior to transfer to the canyon. Elimination of the permanganate treatment of precipitator flushes and recovery by anion exchange does not appear to be limited by the oxalate effect on anion exchange. Np from solutions with higher oxalate to Np molar ratios than expected in precipitator flushes was recovered with low to modest losses. Solubility problems appear to be unlikely when the moles of oxalate involved are less than the total number of moles of Np due to complexation effects. The presence of significant concentrations of iron (Fe) in the solutions will further decrease the probability of Np oxalate precipitation due the formation of Fe oxalate complexes. Np oxalate solubility data in 8 M HNO{sub 3} with from one to six times as much oxalate as Np have

  15. Large Scale Solid Phase Synthesis of Peptide Drugs: Use of Commercial Anion Exchange Resin as Quenching Agent for Removal of Iodine during Disulphide Bond Formation.

    PubMed

    Reddy, K M Bhaskara; Kumari, Y Bharathi; Mallikharjunasarma, Dokka; Bulliraju, Kamana; Sreelatha, Vanjivaka; Ananda, Kuppanna

    2012-01-01

    The S-acetamidomethyl (Acm) or trityl (Trt) protecting groups are widely used in the chemical synthesis of peptides that contain one or more disulfide bonds. Treatment of peptides containing S-Acm protecting group with iodine results in simultaneous removal of the sulfhydryl protecting group and disulfide formation. However, the excess iodine needs to be quenched or adsorbed as quickly as possible after completion of the disulfide bond formation in order to minimize side reactions that are often associated with the iodination step. We report here a simple method for simultaneous quenching and removal of iodine and isolation of disulphide bridge peptides. The use of excess inexpensive anion exchange resin to the oxidized peptide from the aqueous acetic acid/methanol solution affords quantitative removal of iodine and other color impurities. This improves the resin life time of expensive chromatography media that is used in preparative HPLC column during the purification of peptide using preparative HPLC. Further, it is very useful for the conversion of TFA salt to acetate in situ. It was successfully applied commercially, to the large scale synthesis of various peptides including Desmopressin, Oxytocin, and Octreotide. This new approach offers significant advantages such as more simple utility, minimal side reactions, large scale synthesis of peptide drugs, and greater cost effectiveness.

  16. Large Scale Solid Phase Synthesis of Peptide Drugs: Use of Commercial Anion Exchange Resin as Quenching Agent for Removal of Iodine during Disulphide Bond Formation

    PubMed Central

    Reddy, K. M. Bhaskara; Kumari, Y. Bharathi; Mallikharjunasarma, Dokka; Bulliraju, Kamana; Sreelatha, Vanjivaka; Ananda, Kuppanna

    2012-01-01

    The S-acetamidomethyl (Acm) or trityl (Trt) protecting groups are widely used in the chemical synthesis of peptides that contain one or more disulfide bonds. Treatment of peptides containing S-Acm protecting group with iodine results in simultaneous removal of the sulfhydryl protecting group and disulfide formation. However, the excess iodine needs to be quenched or adsorbed as quickly as possible after completion of the disulfide bond formation in order to minimize side reactions that are often associated with the iodination step. We report here a simple method for simultaneous quenching and removal of iodine and isolation of disulphide bridge peptides. The use of excess inexpensive anion exchange resin to the oxidized peptide from the aqueous acetic acid/methanol solution affords quantitative removal of iodine and other color impurities. This improves the resin life time of expensive chromatography media that is used in preparative HPLC column during the purification of peptide using preparative HPLC. Further, it is very useful for the conversion of TFA salt to acetate in situ. It was successfully applied commercially, to the large scale synthesis of various peptides including Desmopressin, Oxytocin, and Octreotide. This new approach offers significant advantages such as more simple utility, minimal side reactions, large scale synthesis of peptide drugs, and greater cost effectiveness. PMID:23118772

  17. Single particle electron microscopy analysis of the bovine anion exchanger 1 reveals a flexible linker connecting the cytoplasmic and membrane domains.

    PubMed

    Jiang, Jiansen; Magilnick, Nathaniel; Tsirulnikov, Kirill; Abuladze, Natalia; Atanasov, Ivo; Ge, Peng; Narla, Mohandas; Pushkin, Alexander; Zhou, Z Hong; Kurtz, Ira

    2013-01-01

    Anion exchanger 1 (AE1) is the major erythrocyte membrane protein that mediates chloride/bicarbonate exchange across the erythrocyte membrane facilitating CO₂ transport by the blood, and anchors the plasma membrane to the spectrin-based cytoskeleton. This multi-protein cytoskeletal complex plays an important role in erythrocyte elasticity and membrane stability. An in-frame AE1 deletion of nine amino acids in the cytoplasmic domain in a proximity to the membrane domain results in a marked increase in membrane rigidity and ovalocytic red cells in the disease Southeast Asian Ovalocytosis (SAO). We hypothesized that AE1 has a flexible region connecting the cytoplasmic and membrane domains, which is partially deleted in SAO, thus causing the loss of erythrocyte elasticity. To explore this hypothesis, we developed a new non-denaturing method of AE1 purification from bovine erythrocyte membranes. A three-dimensional (3D) structure of bovine AE1 at 2.4 nm resolution was obtained by negative staining electron microscopy, orthogonal tilt reconstruction and single particle analysis. The cytoplasmic and membrane domains are connected by two parallel linkers. Image classification demonstrated substantial flexibility in the linker region. We propose a mechanism whereby flexibility of the linker region plays a critical role in regulating red cell elasticity.

  18. Single Particle Electron Microscopy Analysis of the Bovine Anion Exchanger 1 Reveals a Flexible Linker Connecting the Cytoplasmic and Membrane Domains

    PubMed Central

    Abuladze, Natalia; Atanasov, Ivo; Ge, Peng; Narla, Mohandas; Pushkin, Alexander; Zhou, Z. Hong; Kurtz, Ira

    2013-01-01

    Anion exchanger 1 (AE1) is the major erythrocyte membrane protein that mediates chloride/bicarbonate exchange across the erythrocyte membrane facilitating CO2 transport by the blood, and anchors the plasma membrane to the spectrin-based cytoskeleton. This multi-protein cytoskeletal complex plays an important role in erythrocyte elasticity and membrane stability. An in-frame AE1 deletion of nine amino acids in the cytoplasmic domain in a proximity to the membrane domain results in a marked increase in membrane rigidity and ovalocytic red cells in the disease Southeast Asian Ovalocytosis (SAO). We hypothesized that AE1 has a flexible region connecting the cytoplasmic and membrane domains, which is partially deleted in SAO, thus causing the loss of erythrocyte elasticity. To explore this hypothesis, we developed a new non-denaturing method of AE1 purification from bovine erythrocyte membranes. A three-dimensional (3D) structure of bovine AE1 at 2.4 nm resolution was obtained by negative staining electron microscopy, orthogonal tilt reconstruction and single particle analysis. The cytoplasmic and membrane domains are connected by two parallel linkers. Image classification demonstrated substantial flexibility in the linker region. We propose a mechanism whereby flexibility of the linker region plays a critical role in regulating red cell elasticity. PMID:23393575

  19. Diels Alder polyphenylene anion exchange membrane for nonaqueous redox flow batteries

    DOE PAGES

    Small, Leo J.; Pratt, III, Harry D.; Fujimoto, Cy H.; ...

    2015-10-23

    Here highly conductive, solvent-resistant anionic Diels Alder polyphenylene (DAPP) membranes were synthesized with three different ionic contents and tested in an ionic liquid-based nonaqueous redox flow battery (RFB). These membranes display 3–10× increase in conductivity in propylene carbonate compared to some commercially available (aqueous) anion exchange membranes. The membrane with an ion content of 1.5 meq/g (DAPP1.5) proved too brittle for operation in a RFB, while the membrane with an ion content of 2.5 meq/g (DAPP2.5) allowed excessive movement of solvent and poor electrochemical yields (capacity fade). Despite having lower voltage efficiencies compared to DAPP2.5, the membrane with an intermediatemore » ion content of 2.0 meq/g (DAPP2.0) exhibited higher coulombic efficiencies (96.4% vs. 89.1%) and electrochemical yields (21.6% vs. 10.9%) after 50 cycles. Crossover of the electroactive species was the primary reason for decreased electrochemical yields. Analysis of the anolyte and catholyte revealed degradation of the electroactive species and formation of a film at the membrane-solution interface. Increases in membrane resistance were attributed to mechanical and thermal aging of the membrane; no chemical change was observed. As a result, improvements in the ionic selectivity and ionic conductivity of the membrane will increase the electrochemical yield and voltage efficiency of future nonaqueous redox flow batteries.« less

  20. Diels Alder polyphenylene anion exchange membrane for nonaqueous redox flow batteries

    SciTech Connect

    Small, Leo J.; Pratt, III, Harry D.; Fujimoto, Cy H.; Anderson, Travis M.

    2015-10-23

    Here highly conductive, solvent-resistant anionic Diels Alder polyphenylene (DAPP) membranes were synthesized with three different ionic contents and tested in an ionic liquid-based nonaqueous redox flow battery (RFB). These membranes display 3–10× increase in conductivity in propylene carbonate compared to some commercially available (aqueous) anion exchange membranes. The membrane with an ion content of 1.5 meq/g (DAPP1.5) proved too brittle for operation in a RFB, while the membrane with an ion content of 2.5 meq/g (DAPP2.5) allowed excessive movement of solvent and poor electrochemical yields (capacity fade). Despite having lower voltage efficiencies compared to DAPP2.5, the membrane with an intermediate ion content of 2.0 meq/g (DAPP2.0) exhibited higher coulombic efficiencies (96.4% vs. 89.1%) and electrochemical yields (21.6% vs. 10.9%) after 50 cycles. Crossover of the electroactive species was the primary reason for decreased electrochemical yields. Analysis of the anolyte and catholyte revealed degradation of the electroactive species and formation of a film at the membrane-solution interface. Increases in membrane resistance were attributed to mechanical and thermal aging of the membrane; no chemical change was observed. As a result, improvements in the ionic selectivity and ionic conductivity of the membrane will increase the electrochemical yield and voltage efficiency of future nonaqueous redox flow batteries.

  1. Quaternized dimethylaminoethyl methacrylate strong base anion exchange fibers for As(V) adsorption

    NASA Astrophysics Data System (ADS)

    Kavaklı, Cengiz; Akkaş Kavaklı, Pınar; Turan, Burcu Dila; Hamurcu, Aslı; Güven, Olgun

    2014-09-01

    N,N-Dimethylaminoethyl methacrylate (DMAEMA) grafted polyethylene/polypropylene (PE/PP) nonwoven fibers (DMAEMA-g-PE/PP) was prepared by radiation-induced graft polymerization. DMAEMA graft chains on nonwoven fibers were quaternized with dimethyl sulfate solution for the preparation of strong base anion exchange fibers (QDMAEMA-g-PE/PP). Fiber structures were characterized by FTIR, XPS and SEM techniques. The effect of solution pH, contact time, initial As(V) ion concentration and coexisting ions on the As(V) adsorption capacity of the QDMAEMA-g-PE/PP fibers were investigated by performing batch adsorption experiments. The adsorption of As(V) by QDMAEMA-g-PE/PP fibers was found to be independent on solution pH in the range 4.00-10.00. Kinetic experiments show that the As(V) adsorption rate was rapid and As(V) adsorption follows pseudo second-order kinetic model. As(V) adsorption equilibrium data were analyzed using Langmuir and Freundlich adsorption isotherm model equations. Langmuir and Freundlich adsorption isotherm models fitted the experimental data well. The maximum adsorption capacity (qmax) calculated from Langmuir isotherm was found to be 83.33 mg As(V)/g polymer at pH 7.00. The adsorbent was used for three cycles without significant loss of adsorption capacity. The adsorbed As(V) ions were desorbed effectively by a 0.1 M NaOH solution.

  2. Analysis of diffusion models for protein adsorption to porous anion-exchange adsorbent.

    PubMed

    Chen, Wei-Dong; Dong, Xiao-Yan; Sun, Yan

    2002-07-12

    The ion-exchange adsorption kinetics of bovine serum albumin (BSA) and gamma-globulin to an anion exchanger, DEAE Spherodex M, has been studied by batch adsorption experiments. Various diffusion models, that is, pore diffusion, surface diffusion, homogeneous diffusion and parallel diffusion models, are analyzed for their suitabilities to depict the adsorption kinetics. Protein diffusivities are estimated by matching the models with the experimental data. The dependence of the diffusivities on initial protein concentration is observed and discussed. The adsorption isotherm of BSA is nearly rectangular, so there is little surface diffusion. As a result, the surface and homogeneous diffusion models do not fit to the kinetic data of BSA adsorption. The adsorption isotherm of gamma-globulin is less favorable, and the surface diffusion contributes greatly to the mass transport. Consequently, both the surface and homogeneous diffusion models fit to the kinetic data of gamma-globulin well. The adsorption kinetics of BSA and gamma-globulin can be very well fitted by parallel diffusion model, because the model reflects correctly the intraparticle mass transfer mechanism. In addition, for both the favorably bound proteins, the pore diffusion model fits the adsorption kinetics reasonably well. The results here indicate that the pore diffusion model can be used as a good approximate to depict protein adsorption kinetics for protein adsorption systems from rectangular to linear isotherms.

  3. Accounting for host cell protein behavior in anion-exchange chromatography.

    PubMed

    Swanson, Ryan K; Xu, Ruo; Nettleton, Daniel S; Glatz, Charles E

    2016-11-01

    Host cell proteins (HCP) are a problematic set of impurities in downstream processing (DSP) as they behave most similarly to the target protein during separation. Approaching DSP with the knowledge of HCP separation behavior would be beneficial for the production of high purity recombinant biologics. Therefore, this work was aimed at characterizing the separation behavior of complex mixtures of HCP during a commonly used method: anion-exchange chromatography (AEX). An additional goal was to evaluate the performance of a statistical methodology, based on the characterization data, as a tool for predicting protein separation behavior. Aqueous two-phase partitioning followed by two-dimensional electrophoresis provided data on the three physicochemical properties most commonly exploited during DSP for each HCP: pI (isoelectric point), molecular weight, and surface hydrophobicity. The protein separation behaviors of two alternative expression host extracts (corn germ and E. coli) were characterized. A multivariate random forest (MVRF) statistical methodology was then applied to the database of characterized proteins creating a tool for predicting the AEX behavior of a mixture of proteins. The accuracy of the MVRF method was determined by calculating a root mean squared error value for each database. This measure never exceeded a value of 0.045 (fraction of protein populating each of the multiple separation fractions) for AEX. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1453-1463, 2016.

  4. Synthesis and Characterization of Imidazolium Linear Bisphenol Polycarbonate Hydroxides for Anion Exchange Membrane.

    PubMed

    Jang, Hohyoun; Hossain, Md Awlad; Lee, Soonho; Ha, Jaesung; Yoo, Jihoo; Kim, Kyungchul; Kim, Whangi

    2015-11-01

    A novel anion exchange membrane of imidazolium functionalized bisphenol polycarbonate was prepared for application in alkaline fuel cell. Di-imidazolium polycarbonate anionic membrane was synthesized by sequential interfacial polymerization, chloromethylation, substitution with 1-methylimidazole and ion exchange with 1.0 M KOH. Chloromethylation reaction was quantitative to achieve a high content of hydroxide ions. Introduction of conjugated imidazole ring in polymer plays an important role to improve both thermal and chemical stability. Bisphenol polycarbonate is a flexible polymer and shows a good solubility in polar organic solvent. The alkaline imidazolium bisphenol polycarbonate rendered an elevated molecular weight with excellent solubility in polar aprotic solvent. Different levels of substitution and ion exchange were investigated; the resulting membranes showed high ion exchange capacities (IECs) of up to 2.15 mmol g(-1). The imidazolium-functionalized copolymer membranes showed lower water affinity (14.2-42.8% at 30 degrees C) that satisfied an essential criterion for fuel cell application. The chemical structure of the imidazolium functionalized polycarbonate membrane was confirmed by 1H NMR spectroscopy, and also the membrane properties were evaluated by thermogravimetric analysis (TGA) and water uptake (WU), IEC and conductivity assessment. They exhibited hydroxide conductivity above 10(-2) S cm(-1) at room temperature and good chemical stability for up to five days without significant losses of ion conductivity.

  5. Influence of Hydration Level on Polymer and Water Dynamics in Alkaline Anion Exchange Fuel Cell Membranes

    NASA Astrophysics Data System (ADS)

    Tarver, Jacob; Kim, Jenny; Tyagi, Madhu; Soles, Christopher; Tsai, Tsung-Han; Coughlin, Bryan

    2015-03-01

    Triblock copolymers based on poly(chloromethylstyrene)-b-poly(ethylene)-b-poly(chloromethylstyrene) can be quaternized to different extents to yield anion exchange membranes for alkaline fuel cells. In the absence of moisture, these membranes demonstrate bilayer lamellar morphology. Upon high levels of hydration, however, in-situ small angle neutron scattering reveals the emergence of higher-order diffraction peaks. This phenomena has previously been observed in analogous diblock copolymer-based membranes and has been attributed to the induction of a multilayer lamellar morphology in which selective striping of water occurs in the center of the ion-rich domain. By conducting humidity-resolved quasielastic neutron scattering (QENS) measurements using deuterated water, we are able to isolate differences in the pico- to nanosecond timescale dynamics of the hydrogenated membrane upon hydration. QENS measurements in the presence of a hydrogenated water source subsequently permit deconvolution and isolation of the translational and rotational dynamics of water as a function of relative humidity, revealing spatial and temporal changes in polymer and water motion at high levels of hydration.

  6. Synthesis and Structure-Property Relationships of Poly(sulfone)s for Anion Exchange Membranes

    SciTech Connect

    Yan, JL; Moore, HD; Hibbs, MR; Hickner, MA

    2013-10-05

    Membranes based on cationic polymers that conduct anions are important for enabling alkaline membrane fuel cells and other solid-state electrochemical devices that operate at high pH. Anion exchange membranes with poly(arylene ether sulfone) backbones are demonstrated by two routes: chloromethylation of commercially available poly(sulfone)s or radical bromination of benzylmethyl moieties in poly(sulfone)s containing tetramethylbisphenol A monomer residues. Polymers with tethered trimethylbenzyl ammonium moieties resulted from conversion of the halomethyl groups by quaternization with trimethyl amine. The water uptake of the chloromethylated polymers was dependent on the type of poly(sulfone) backbone for a given IEC. Bisphenol A-based Udel (R) poly(sulfone) membranes swelled in water to a large extent while membranes from biphenol-based Radel (R) poly(sulfone), a stiffer backbone than Udel, only showed moderate water uptake. The water uptake of cationic poly(sulfone)s was further reduced by synthesizing tetramethylbisphenol A and 4,4-biphenol-containing poly(sulfone) copolymers where the ionic groups were clustered on the tetramethylbisphenol A residues. The conductivity of all samples scaled with the bulk water uptake. The hydration number of the membranes could be increased by casting membranes from the ionic form polymers versus converting the halomethyl form cast polymers to ionic form in the solid state. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1790-1798, 2013

  7. Synthesis, characterisation and anion exchange properties of copper, magnesium, zinc and nickel hydroxy nitrates

    SciTech Connect

    Biswick, Timothy; Jones, William . E-mail: wj10@cam.ac.uk; Pacula, Aleksandra; Serwicka, Ewa

    2006-01-15

    Anion exchange reactions of four structurally related hydroxy salts, Cu{sub 2}(OH){sub 3}NO{sub 3}, Mg{sub 2}(OH){sub 3}NO{sub 3}, Ni{sub 2}(OH){sub 3}NO{sub 3} and Zn{sub 3}(OH){sub 4}(NO{sub 3}){sub 2} are compared and trends rationalised in terms of the strength of the covalent bond between the nitrate group and the matrix cation. Powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and elemental analysis are used to characterise the materials. Replacement of the nitrate anions in the zinc and copper salts with benzoate anions is possible although exchange of the zinc salt is accompanied by modification of the layer structure from one where zinc is exclusively six-fold coordinated to a structure where there is both six- and four-fold zinc coordination. Magnesium and nickel hydroxy nitrates, on the other hand, hydrolyse to their respective metal hydroxides. -- Graphical abstract: PXRD patterns of exchange products of (a) Zn{sub 3}(OH){sub 4}(NO{sub 3}){sub 2} (b) Zn{sub 5}(OH){sub 8}(NO{sub 3}){sub 2}.2H{sub 2}O and (c) Cu{sub 2}(OH){sub 3}NO{sub 3} with benzoate anions.

  8. Reversible air electrodes integrated with an anion-exchange membrane for secondary air batteries

    NASA Astrophysics Data System (ADS)

    Fujiwara, Naoko; Yao, Masaru; Siroma, Zyun; Senoh, Hiroshi; Ioroi, Tsutomu; Yasuda, Kazuaki

    Reversible air electrodes integrated with a polymer electrolyte membrane have been proposed for use in rechargeable metal-air batteries or unitized regenerative fuel cells to reduce the impact of atmospheric carbon dioxide. Reversible air electrodes were prepared with an anion-exchange membrane (AEM) as a polymer electrolyte membrane and platinum-based catalysts. The AEM at the interface between the alkaline electrolyte and the air electrode layer plays major roles in AEM-type air electrodes as follows: it blocks (a) the permeation of cations in the alkaline electrolyte into the air electrode layer to prevent carbonate precipitation, (b) penetration of the alkaline solution itself, and (c) neutralization of the alkaline electrolyte by carbon dioxide, all of which prevent performance degradation of oxygen reactions. Catalysts for decreasing the overvoltage of oxygen reactions were also investigated with the AEM-type air electrode, and the overall efficiency was improved due to a remarkable decrease in the potential for the oxygen evolution reaction with Pt-Ir catalysts.

  9. High performance ion chromatography of haloacetic acids on macrocyclic cryptand anion exchanger.

    PubMed

    Bruzzoniti, Maria Concetta; De Carlo, Rosa Maria; Horvath, Krisztian; Perrachon, Daniela; Prelle, Ambra; Tófalvi, Renáta; Sarzanini, Corrado; Hajós, Péter

    2008-04-11

    A new high performance ion chromatographic method has been developed for the separation of the nine chlorinated-brominated haloacetic acids (HAAs) that are the disinfection by-products of chlorination of drinking water, using a macrocycle-based adjustable-capacity anion-exchange separator column (IonPac Cryptand A1). A gradient method based on theoretical and experimental considerations has been optimized in which 10 mM NaOH-LiOH step gradient was performed at the third minute of the analysis. The optimized method allowed us to separate the nine HAAs and seven possibly interfering inorganic anions in less than 25 min with acceptable resolution. The minimum concentrations detectable for HAAs were between 8.0 (MBA) and 210 (TBA) microg L(-1), with linearity included between 0.9947 (TBA) and 0.9998 (MBA). To increase sensitivity, a 25-fold preconcentration step on a reversed phase substrate (LiChrolut EN) has been coupled. Application of this method to the analysis of haloacetic acids in real tap water samples is illustrated.

  10. Poly(phenyl sulfone) anion exchange membranes with pyridinium groups for vanadium redox flow battery applications

    NASA Astrophysics Data System (ADS)

    Zhang, Bengui; Zhang, Enlei; Wang, Guosheng; Yu, Ping; Zhao, Qiuxia; Yao, Fangbo

    2015-05-01

    To develop high performance and cost-effective membranes with low permeability of vanadium ions for vanadium redox flow battery (VRFB) application, poly(phenyl sulfone) anion exchange membranes with pyridinium groups (PyPPSU) are prepared and first investigated for VRFB application. PyPPSU membranes show much lower vanadium ions permeability (0.07 × 10-7-0.15 × 10-7 cm2 min-1) than that of Nafion 117 membrane (31.3 × 10-7 cm2 min-1). As a result, the self-discharge duration of the VRFB cell with PyPPSU membrane (418 h) is about four times longer than that of VRFB cell with Nafion 117 membrane (110 h). Furthermore, the VRFB cell with PyPPSU membrane exhibits higher battery efficiency (coulombic efficiency of 97.8% and energy efficiency of 80.2%) compare with that of VRFB cell with Nafion 117 membrane (coulombic efficiency of 96.1% and energy efficiency of 77.2%) at a high current density of 100 mA cm-2. In addition, PyPPSU membrane exhibits stable performance in 100-cycle test. The results indicate that PyPPSU membrane is high performance and low-cost alternative membrane for VRFB application.

  11. Understanding and modeling removal of anionic organic contaminants (AOCs) by anion exchange resins.

    PubMed

    Zhang, Huichun; Shields, Anthony J; Jadbabaei, Nastaran; Nelson, Maurice; Pan, Bingjun; Suri, Rominder P S

    2014-07-01

    Ionic organic contaminants (OCs) are a growing concern for water treatment and the environment and are removed inefficiently by many existing technologies. This study examined removal of anionic OCs by anion exchange resins (AXRs) as a promising alternative. Results indicate that two polystyrene AXRs (IRA910 and IRA96) have higher sorption capacities and selectivity than a polyacrylate resin (A860). For the polystyrene resins, selectivity follows: phenolates ≥ aromatic dicarboxylates > aromatic monocarboxylates > benzenesulfonate > aliphatic carboxylates. This trend can be explained based on hydration energy, the number of exchange groups, and aromaticity and hydrophobicity of the nonpolar moiety (NPM) of the anions. For A860, selectivity only varies within a narrow range (0.13-1.64). Despite the importance of the NPM of the anions, neutral solutes were sorbed much less, indicating synergistic combinations of electrostatic and nonelectrostatic interactions in the overall sorption. By conducting multiple linear regression between Abraham's descriptors and nature log of selectivity, induced dipole-related interactions and electrostatic interactions were found to be the most important interaction forces for sorption of the anions, while solute H-bond basicity has a negative effect. A predictive model was then developed for carboxylates and phenolates based on the poly parameter linear free energy relationships established for a diverse range of 16 anions and 5 neutral solutes, and was validated by accurate prediction of sorption of five test solutes within a wide range of equilibrium concentrations and that of benzoate at different pH.

  12. PLUTONIUM LOADING CAPACITY OF REILLEX HPQ ANION EXCHANGE COLUMN - AFS-2 PLUTONIUM FLOWSHEET FOR MOX

    SciTech Connect

    Kyser, E.; King, W.; O'Rourke, P.

    2012-07-26

    Radioactive plutonium (Pu) anion exchange column experiments using scaled HB-Line designs were performed to investigate the dependence of column loading performance on the feed composition in the H-Canyon dissolution process for plutonium oxide (PuO{sub 2}) product shipped to the Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF). These loading experiments show that a representative feed solution containing {approx}5 g Pu/L can be loaded onto Reillex{trademark} HPQ resin from solutions containing 8 M total nitrate and 0.1 M KF provided that the F is complexed with Al to an [Al]/[F] molar ratio range of 1.5-2.0. Lower concentrations of total nitrate and [Al]/[F] molar ratios may still have acceptable performance but were not tested in this study. Loading and washing Pu losses should be relatively low (<1%) for resin loading of up to 60 g Pu/L. Loading above 60 g Pu/L resin is possible, but Pu wash losses will increase such that 10-20% of the additional Pu fed may not be retained by the resin as the resin loading approaches 80 g Pu/L resin.

  13. Enhanced performance of anion exchange membranes via crosslinking of ion cluster regions for fuel cells

    NASA Astrophysics Data System (ADS)

    Lai, Ao Nan; Guo, Dong; Lin, Chen Xiao; Zhang, Qiu Gen; Zhu, Ai Mei; Ye, Mei Ling; Liu, Qing Lin

    2016-09-01

    Development of anion exchange membranes (AEMs) with high hydroxide conductivity, good dimensional and alkaline stabilities is still a challenge for the practical application of AEM fuel cells. In this study, we report a new strategy to prepare high-performance AEMs with crosslinked ionic regions. A series of phenolphthalein-containing poly(arylene ether sulfone)s crosslinked AEMs was synthesized by grafting ion groups selectively and densely on the phenolphthalein units to form ion clusters that are further crosslinked to generate the hydrophilic ionic regions. The crosslinking reaction not only improved the dimensional stability of the AEMs, but also increased the aggregation of the ion clusters leading to the formation of hydrophilic/hydrophobic phase-separated morphology and ion-conducting channels. As a result, enhancements in both ion conductivity and dimensional stability can be achieved. The crosslinked AEMs showed high hydroxide conductivities in the range of 52.2-143.4 mS cm-1 from 30 to 80 °C and a superb ratio of relative conductivity to relative swelling at 80 °C. Furthermore, the crosslinked AEMs also exhibited good mechanical properties, thermal and alkaline stabilities and desirable single cell performance. This work presents a promising strategy for the synthesis of high-performance AEMs for fuel cells.

  14. Tunable High Performance Cross-Linked Alkaline Anion Exchange Membranes for Fuel Cell Applications

    SciTech Connect

    Robertson, Nicholas J.; Kostalik, IV, Henry A.; Clark, Timothy J.; Mutolo, Paul F.; Abruña, Héctor D.; Coates, Geoffrey W.

    2010-02-23

    Fuel cells are energy conversion devices that show great potential in numerous applications ranging from automobiles to portable electronics. However, further development of fuel cell components is necessary for them to become commercially viable. One component critical to their performance is the polymer electrolyte membrane, which is an ion conductive medium separating the two electrodes. While proton conducting membranes are well established (e.g., Nafion), hydroxide conducting membranes (alkaline anion exchange membranes, AAEMs) have been relatively unexplored by comparison. Operating under alkaline conditions offers significant efficiency benefits, especially for the oxygen reduction reaction; therefore, effective AAEMs could significantly advance fuel cell technologies. Here we demonstrate the use of ring-opening metathesis polymerization to generate new cross-linked membrane materials exhibiting high hydroxide ion conductivity and good mechanical properties. Cross-linking allows for increased ion incorporation, which, in turn supports high conductivities. This facile synthetic approach enables the preparation of cross-linked materials with the potential to meet the demands of hydrogen-powered fuel cells as well as direct methanol fuel cells.

  15. Anion exchange chromatographic separation of inositol phosphates and their quantification by gas chromatography.

    PubMed

    Heathers, G P; Juehne, T; Rubin, L J; Corr, P B; Evers, A S

    1989-01-01

    The direct measurement of mass of inositol trisphosphate from biologic samples is described. Separation of inositol monophosphate, bisphosphate, trisphosphate, and inositol tetrakisphosphate was achieved using anion exchange chromatography with a sodium sulfate gradient. In addition, separation of the isomers of each inositol phosphate was performed using HPLC procedures. The individual inositol phosphate fractions were subsequently dephosphorylated and desalted. The myo-inositol from each fraction was then derivatized to the hexatrimethylsilyl derivative and the myo-inositol derivatives were quantified by a novel gas chromatographic analysis using the hexatrimethylsilyl derivative of chiro-inositol as an internal concentration reference. This method is a reproducible and relatively rapid procedure for the direct quantification of inositol phosphate mass which overcomes many of the problems associated with the use of radiolabeled precursors. The method is a significant improvement over existing procedures for the quantitative determination of the mass of inositol phosphate by virtue of improved recovery, sensitivity, and technical simplicity. The applicability of this method is illustrated by the quantitative determination of inositol trisphosphate in response to norepinephrine stimulation of adult canine myocytes and cerebral cortical brain slices and by measurement of the isomers of inositol trisphosphate in isolated myocytes.

  16. Polyphenylene sulfide based anion exchange fiber: synthesis, characterization and adsorption of Cr(VI).

    PubMed

    Huang, Jiajia; Zhang, Xin; Bai, Lingling; Yuan, Siguo

    2012-01-01

    A fibrous strong base anion exchanger (QAPPS) was prepared for the first time via chloromethylation and quaternary amination reaction of polyphenylene sulfide fiber (PPS), and its physical-chemical structure and adsorption behavior for Cr(VI) were characterized by FTIR, Energy Dispersive Spectrometry, TG-DTG, elemental analysis and batch adsorptive technique, respectively. The novel fibrous adsorbent could effectively adsorb Cr(VI) over the pH range 1-12, the maximum adsorption capacity was 166.39 mg/g at pH 3.5, and the adsorption behavior could be described well by Langmuir isotherm equation model. The adsorption kinetics was studied using pseudo first-order and pseudo second-order models, and the t1/2 and equilibrium adsorption time were 5 and 20 min respectively when initial Cr(VI) concentration was 100 mg/L. The saturated fibers could be regenerated rapidly by a mixed solution of 0.5 mol/L NaOH and 0.5 mol/L NaCl, and the adsorption capacity was well maintained after six adsorption-desorption cycles.

  17. Multilayer chitosan-based open tubular capillary anion exchange column with integrated monolithic capillary suppressor.

    PubMed

    Huang, Xiaojia; Foss, Frank W; Dasgupta, Purnendu K

    2011-11-30

    We describe a multilayered open tubular anion exchange column fabricated by alternately pumping solutions of chitosan and glutaraldehyde. The column is terminated in an integrally bonded monolithic suppressor cast around a mandrel of a tungsten wire, composed of an acrylic acid (AA)-ethylene dimethacrylate (EDMA) monolith that is made with sufficient porogen for the monolith to function as a membrane. For a 4.5m long 75 μm bore column coated with 24 successive layers of the condensation polymer (estimated to contain ~72 molecular layers) and coupled to 1cm length of a suppressor fabricated with 55-60% AA, effective separation of several common anions (F(-), Cl(-), NO(2)(-), Br(-), NO(3)(-), average number of theoretical plates ~12,000) and adequate suppression of 1 mM KOH used as eluent was observed at a flow rate of 800 nL min(-1) to obtain sub-picomol detection limits at an operating pressure of ~1 bar. The separation is not time efficient but the system can be meritorious in unique niche applications where a small form factor is desired and liquid volume and power consumption are more important than separation speed.

  18. The structure and organization of the human erythroid anion exchanger (AE1) gene

    SciTech Connect

    Sahr, K.E.; Taylor, W.M.; Daniels, B.P.

    1994-12-01

    The AE1 (anion exchanger, band 3) protein is expressed in erythrocytes and in the A-type intercalated cells of the kidney distal collecting tubule. In both cell types it mediates the electroneutral transport of chloride and bicarbonate ions across the lipid bilayer, and, in erythrocytes, it also serves as the critical attachment site of the peripheral membrane skeleton. We have characterized the human AE1 gene using overlapping clones isolated from a phage library of human genomic DNA. The gene spans {approximately}20 kb and consists of 20 exons separated by 19 introns. The structure of the human AE1 gene corresponds closely with that of the previously characterized mouse AE1 gene, with a high degree of conservation of exon/intron junctions, as well as exon and intron nucleotide sequences. The putative upstream and internal promoter sequences of the human AE1 gene used in erythroid and kidney cells, respectively, are described. We also report the nucleotide sequence of the entire 3{prime} noncoding region of exon 20, which was lacking in the published cDNA sequences. In addition, we have characterized 9 Alu repeat elements found within the body of the human AE1 gene that are members of 4 related subfamilies that appear to have entered the genome at different times during primate evolution. 59 refs., 5 figs., 2 tabs.

  19. Perchlorate adsorption and desorption on activated carbon and anion exchange resin.

    PubMed

    Yoon, In-Ho; Meng, Xiaoguang; Wang, Chao; Kim, Kyoung-Woong; Bang, Sunbaek; Choe, Eunyoung; Lippincott, Lee

    2009-05-15

    The mechanisms of perchlorate adsorption on activated carbon (AC) and anion exchange resin (SR-7 resin) were investigated using Raman, FTIR, and zeta potential analyses. Batch adsorption and desorption results demonstrated that the adsorption of perchlorate by AC and SR-7 resin was reversible. The reversibility of perchlorate adsorption by the resin was also proved by column regeneration test. Solution pH significantly affected perchlorate adsorption and the zeta potential of AC, while it did not influence perchlorate adsorption and the zeta potential of resin. Zeta potential measurements showed that perchlorate was adsorbed on the negatively charged AC surface. Raman spectra indicated the adsorption resulted in an obvious position shift of the perchlorate peak, suggesting that perchlorate was associated with functional groups on AC at neutral pH through interactions stronger than electrostatic interaction. The adsorbed perchlorate on the resin exhibited a Raman peak at similar position as the aqueous perchlorate, indicating that perchlorate was adsorbed on the resin through electrostatic attraction between the anion and positively charged surface sites.

  20. Organic-inorganic hybrid anion exchange hollow fiber membranes: a novel device for drug delivery.

    PubMed

    Wang, Na; Wu, Cuiming; Cheng, Yiyun; Xu, Tongwen

    2011-04-15

    The clinical use of nonsteroidal anti-inflammatory drugs (NSAIDs) (such as sodium salicylate (NaSA)) for the treatment of chronic arthritis is limited due to the adverse effects and patient non-compliance. In order to solve these problems, anion exchange hollow fiber membranes (AEHFMs) are proposed for the first time here as potential drug carriers. Brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) is used as the starting membrane material. In-situ sol-gel process of γ-methacryloxypropyl trimethoxysilane (γ-MPS) in BPPO matrix is operated so as to enhance the membranes' thermal and dimensional stability. The performances of the membranes in controlled release of the drug (NaSA as the model drug) are improved accordingly. Loading and release experiments illustrate that the hybrid AEHFM can bind salicylate (SA⁻) at a high loading efficiency (28.4%), and the retention of the drug on the membrane matrix is significantly prolonged (drug released in 7 days under physiological condition: 51.9%, neglecting the drug bound by protein). Meanwhile, the membrane is biocompatible and can support the adherence, growth, and survival of human cells. Overall, the prepared AEHFM is a promising scaffolding material for drug delivery and tissue engineering.

  1. Stomatin modulates the activity of the Anion Exchanger 1 (AE1, SLC4A1)

    PubMed Central

    Genetet, Sandrine; Desrames, Alexandra; Chouali, Youcef; Ripoche, Pierre; Lopez, Claude; Mouro-Chanteloup, Isabelle

    2017-01-01

    Anion Exchanger 1 (AE1) and stomatin are integral proteins of the red blood cell (RBC) membrane. Erythroid and kidney AE1 play a major role in HCO3− and Cl− exchange. Stomatins down-regulate the activity of many channels and transporters. Biochemical studies suggested an interaction of erythroid AE1 with stomatin. Moreover, we previously reported normal AE1 expression level in stomatin-deficient RBCs. Here, the ability of stomatin to modulate AE1-dependent Cl−/HCO3− exchange was evaluated using stopped-flow methods. In HEK293 cells expressing recombinant AE1 and stomatin, the permeabilities associated with AE1 activity were 30% higher in cells overexpressing stomatin, compared to cells with only endogenous stomatin expression. Ghosts from stomatin-deficient RBCs and controls were resealed in the presence of pH- or chloride-sensitive fluorescent probes and submitted to inward HCO3− and outward Cl− gradients. From alkalinization rate constants, we deduced a 47% decreased permeability to HCO3− for stomatin-deficient patients. Similarly, kinetics of Cl− efflux, followed by the probe dequenching, revealed a significant 42% decrease in patients. In situ Proximity Ligation Assays confirmed an interaction of AE1 with stomatin, in both HEK recombinant cells and RBCs. Here we show that stomatin modulates the transport activity of AE1 through a direct protein-protein interaction. PMID:28387307

  2. Water uptake, ionic conductivity and swelling properties of anion-exchange membrane

    SciTech Connect

    Duan, QJ; Ge, SH; Wang, CY

    2013-12-01

    Water uptake, ionic conductivity and dimensional change of the anion-exchange membrane made by Tokuyama Corporation (A201 membrane) are investigated at different temperatures and water activities. Specifically, the amount of water taken up by membranes exposed to water vapor and membranes soaked in liquid water is determined. The water uptake of the A201 membrane increases with water content as well as temperature. In addition, water sorption data shows Schroeder's paradox for the AEMs investigated. The swelling properties of the A201 membrane exhibit improved dimensional stability compared with Nafion membrane. Water sorption of the A201 membrane occurs with a substantial negative excess volume of mixing. The threshold value of hydrophilic fraction in the A201 membrane for ionic conductivity is around 0.34, above which, the conductivity begins to rise quickly. This indicates that a change in the connectivity of the hydrophilic domains occurs when hydrophilic fraction approaches 0.34. (C) 2013 Elsevier B.V. All rights reserved.

  3. Characterisation of gunshot residue from three ammunition types using suppressed anion exchange chromatography.

    PubMed

    Gilchrist, Elizabeth; Jongekrijg, Fleur; Harvey, Laura; Smith, Norman; Barron, Leon

    2012-09-10

    Gunshot residue (GSR) is commonly analysed in forensic casework using either scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) or gas chromatography-mass spectrometry (GC-MS). Relatively little work has been reported on the post-discharge GSR content of non-metallic inorganic or low molecular weight organic anions to distinguish between different ammunition types. The development of an analytical method using suppressed micro-bore anion exchange chromatography (IC) is presented for the analysis of GSR. A hydroxide gradient was optimised for the separation of 19 forensically relevant organic and inorganic anions in <23min and sensitivities of the order of 0.12-3.52ng of anion detected for all species were achieved. Along with an optimised extraction procedure, this method was applied to the analysis of post-ignition residues from three selected ammunition types. By profiling and comparing the anionic content in each ammunition residue, the possibility to distinguish between each type using their anionic profiles and absolute weight is presented. The potential for interference is also discussed with respect to sample types which are typically problematic in the analysis of GSR using SEM-EDX and GC-MS. To the best of our knowledge this represents the first study on the analysis of inorganic anions in GSR using suppressed ion chromatography.

  4. Characterisation of brewpub beer carbohydrates using high performance anion exchange chromatography coupled with pulsed amperometric detection.

    PubMed

    Arfelli, Giuseppe; Sartini, Elisa

    2014-01-01

    High performance anion exchange chromatography (HPAEC) coupled with pulsed amperometric detection (PAD) was optimised in order to quantify mannose, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose and maltoheptaose content of beer. The method allows the determination of above mentioned oligosaccharides, in a single chromatographic run, without any pre-treatment. Limit of detection and limit of quantification were suitable for beer. Accuracy and repeatability were good for the entire amount considered. Once optimised HPAEC PAD for the specific matrix, the second goal of this research was to verify the possibility to discriminate beers, depending on their style. The carbohydrates content of brewpub commercial beers was very variable, ranging from 19.3 to 1469mg/L (mannose), 34.5 to 2882mg/L (maltose), 141.9 to 20731mg/L (maltotriose), 168.5 to 7650mg/L (maltotetraose), 20.1 to 2537mg/L (maltopentaose), 22.9 to 3295mg/L (maltohexaose), 8.5 to 2492mg/L (maltoeptaose), even in the same style of beer. However, the carbohydrates content was useful, jointed with other compounds amount, to discriminate different styles of beer. As a matter of fact, principal component analysis put in evidence beer differences considering some fermentation conditions and colour.

  5. Transport of some strong incompletely dissociated acids through anion-exchange membrane.

    PubMed

    Palatý, Zdenek; Záková, Alena

    2003-12-01

    Nitric and sulfuric acids belong among strong incompletely dissociated acids, so that in the description of their transport through an ion-exchange membrane, ionic equilibria have to be taken into account. The paper presents the determination of ionic mobilities and diffusivity of nondissociated form of these acids. For that purpose, data on the dialysis experiments with nitric and sulfuric acids in a batch mixed cell with an anion-exchange membrane NEOSEPTA-AFN, which have been completed by those on the membrane conductivity, have been used. The dependencies of the ionic mobilities and the diffusivity of nondissociated form of nitric acid upon the acid concentration in the membrane have been approximated by second degree polynomials. Their coefficients have been determined by numerical integration of the partial differential equation describing the concentration fields of the acids in the membrane and liquid films on both sides of the membrane, followed by an optimizing procedure. The model used is based on the Nernst-Planck electrodiffusion equation. Using all the experimental data obtained at various acid concentrations and rotational speeds of the stirrers, it has been found that ionic mobility is strongly affected by the acid concentration in the membrane and decreases in the series H(3)O(+), SO(2-)(4), NO(-)(3), HSO(-)(4).

  6. Nature identification and morphology characterization of anion-exchange membrane fouling during conventional electrodialysis.

    PubMed

    Ayala-Bribiesca, Erik; Pourcelly, Gérald; Bazinet, Laurent

    2007-04-01

    The aim of this work was to study the effect on the fouling of anion-exchange membranes (AEM) of (1) the pH value of the concentrate solution and (2) the composition in calcium, carbonate, and protein of the diluate solution to be treated by conventional electrodialysis. It appeared that after demineralization of solutions containing CaCl(2) using a concentrate solution maintained at a pH value of 7 or 12, mineral fouling appeared on the AEM surface in contact with the concentrate. The mineral deposits presented a cylindrical filament shape for conditions with a concentrate solution pH value of 7, while, for a pH value of 12, the mineral deposit had a crumbly and spongy texture formed by irregular aggregates. The nature of the fouling was identified as a calcium phosphate with or without calcium hydroxide. In addition, gel-like protein fouling was detected on the AEM surface in contact with the diluate after demineralization procedures using a concentrate pH value of 2 or 7, regardless of the mineral composition of the diluate.

  7. Performance testing of grout-based waste forms for the solidification of anion exchange resins

    SciTech Connect

    Morgan, I.L.; Bostick, W.D.

    1990-10-01

    The solidification of spent ion exchanges resins in a grout matrix as a means of disposing of spent organic resins produced in the nuclear fuel cycle has many advantages in terms of process simplicity and economy, but associated with the process is the potential for water/cement/resins to interact and degrade the integrity of the waste form solidified. Described in this paper is one possible solution to preserving the integrity of these solidified waste forms: the encapsulation of beaded anion exchange resins in grout formulations containing ground granulated blast furnace slag, Type I-II (mixed) portland cement, and additives (clays, amorphous silica, silica fume, and fly ash). The results of the study reported herein show the cured waste form tested has a low leach rate for nitrate ion from the resin (and a low leach rate is inferred for Tc-99) and acceptable durability as assessed by the water immersion and freezing/thawing test protocols. The results also suggest a tested surrogate waste form prepared in vinyl ester styrene binder performs satisfactorily against the wetting/drying criterion, and it should offer additional insight into future work on the solidification of spent organic resins. 26 refs., 4 figs., 5 tabs.

  8. Phosphate removal from wastewaters using a weak anion exchanger prepared from a lignocellulosic residue.

    PubMed

    Anirudhan, T S; Noeline, B F; Manohar, D M

    2006-04-15

    Surface modifications of lignocellulosic residues has become increasingly important for improving their applications as adsorbents. In this study a new adsorbent system (BS-DMAHP) containing dimethylaminohydroxypropyl (DMAHP) weak base groups was prepared by the reaction of banana stem (BS), a lignocellulosic residue with epichlorohydrin and dimethylamine followed by treatment of hydrochloric acid. The original BS and BS-DMAHP were characterized with the help of surface area analyzer, infrared spectroscopy (IR) and scanning electron microscopy (SEM). Surface charge density of the samples as a function of pH was investigated using potentiometric titrations. Adsorbent exhibits very high adsorption potential for phosphate and more than 99.0% removal was achieved in the pH range of 5.0-7.0. Adsorption has been found to be concentration dependent and endothermic and follows a reversible second-order kinetics. The Langmuir and Freundlich isotherm models were applied to describe the equilibrium data. Equilibrium data agreed very well with the Langmuir model. Adsorption experiments were conducted using a commercial chloride form Duolite A-7, a weak base anion exchanger. The removal efficiency was tested using fertilizer industry wastewater. Adsorbed phosphate on BS-DMAHP can be recovered by treating with 0.1 M NaOH solution. A stability test operated for four cycles indicate a capacity loss of < 12.0%.

  9. Weak anion exchange chromatographic profiling of glycoprotein isoforms on a polymer monolithic capillary.

    PubMed

    Liu, Jing; Ren, Lianbing; Liu, Yunchun; Li, Hengye; Liu, Zhen

    2012-03-09

    High resolution separation of intact glycoproteins, which is essential for many aspects such as finger-print profiling, represents a great challenge because one glycoprotein can exhibit many isoforms with close physicochemical properties. Monolithic columns are important separation media for the separation of intact proteins due to its significant advantages such as easy preparation, high column efficiency and high permeability. However, there are few reports on high resolution profiling of intact glycoproteins. Herein, we presented a polymeric weak anion exchange (WAX) monolithic capillary for high resolution separation of glycoprotein isoforms. A base monolith was first prepared through ring-opening polymerization between tris(2,3-epoxypropyl)isocyanurate and tri(2-aminoethyl), and then modified through reacting with ammonia aqueous solution to convert the unreacted epoxide moieties into primary amino groups. The prepared monolithic capillary was characterized in terms of morphology, pore size, hydrophilicity and reproducibility. The obtained WAX monolithic capillary exhibited desired through-pores and mesopore size, stable skeleton and hydrophilic nature. The performance of the capillary was evaluated using several typical glycoproteins such as α(1)-acid glycoprotein (AGP) as mode analytes. Effects of the experimental parameters on the glycoform resolution were investigated. Under the optimized separation conditions, the tested glycoproteins were all resolved into distinct glycoforms. A comparative investigation with capillary zone electrophoresis (CZE) revealed that this WAX column provided better selectivity as more isoforms were observed, although the resolution of some glycoprotein isoforms decreased.

  10. High-Resolution Coarse-Grained Model of Hydrated Anion-Exchange Membranes that Accounts for Hydrophobic and Ionic Interactions through Short-Ranged Potentials.

    PubMed

    Lu, Jibao; Jacobson, Liam C; Perez Sirkin, Yamila A; Molinero, Valeria

    2017-01-10

    parametrized to reproduce multiple properties of interest for hydrated polyelectrolyte membranes. The CG model of hydrated PPO/TMACl water is about 100 times faster than the reference atomistic GAFF-TIP4P/2005 model. The strategy implemented here can be used in the parametrization of CG models for other substances, such as biomolecular systems and membranes for desalination, water purification, and redox flow batteries. We anticipate that the large spatial and temporal simulations made possible by the CG model will advance the quest for anion-exchange membranes with improved transport and mechanical properties.

  11. Multi-modal applicability of a reversed-phase/weak-anion exchange material in reversed-phase, anion-exchange, ion-exclusion, hydrophilic interaction and hydrophobic interaction chromatography modes.

    PubMed

    Lämmerhofer, Michael; Nogueira, Raquel; Lindner, Wolfgang

    2011-06-01

    We recently introduced a mixed-mode reversed-phase/weak anion-exchange type separation material based on silica particles which consisted of a hydrophobic alkyl strand with polar embedded groups (thioether and amide functionalities) and a terminal weak anion-exchange-type quinuclidine moiety. This stationary phase was designed to separate molecules by lipophilicity and charge differences and was mainly devised for peptide separations with hydroorganic reversed-phase type elution conditions. Herein, we demonstrate the extraordinary flexibility of this RP/WAX phase, in particular for peptide separations, by illustrating its applicability in various chromatographic modes. The column packed with this material can, depending on the solute character and employed elution conditions, exploit attractive or repulsive electrostatic interactions, and/or hydrophobic or hydrophilic interactions as retention and selectivity increments. As a consequence, the column can be operated in a reversed-phase mode (neutral compounds), anion-exchange mode (acidic compounds), ion-exclusion chromatography mode (cationic solutes), hydrophilic interaction chromatography mode (polar compounds), and hydrophobic interaction chromatography mode (e.g., hydrophobic peptides). Mixed-modes of these chromatographic retention principles may be materialized as well. This allows an exceptionally flexible adjustment of retention and selectivity by tuning experimental conditions. The distinct separation mechanisms will be outlined by selected examples of peptide separations in the different modes.

  12. Formation of periodic interfacial misfit dislocation array at the InSb/GaAs interface via surface anion exchange

    NASA Astrophysics Data System (ADS)

    Jia, Bo Wen; Tan, Kian Hua; Loke, Wan Khai; Wicaksono, Satrio; Yoon, Soon Fatt

    2016-07-01

    The relationship between growth temperature and the formation of periodic interfacial misfit (IMF) dislocations via the anion exchange process in InSb/GaAs heteroepitaxy was systematically investigated. The microstructural and electrical properties of the epitaxial layer were characterized using atomic force microscope, high-resolution x-ray diffraction, transmission electron microscopy, and Hall resistance measurement. The formation of interfacial misfit (IMF) dislocation arrays depended on growth temperature. A uniformly distributed IMF array was found in a sample grown at 310 °C, which also exhibited the lowest threading dislocation density. The analysis suggested that an incomplete As-for-Sb anion exchange process impeded the formation of IMF on sample grown above 310 °C. At growth temperature below 310 °C, island coalescence led to the formation of 60° dislocations and the disruption of periodic IMF array. All samples showed higher electron mobility at 300 K than at 77 K.

  13. Magnetic cellulose ionomer/layered double hydroxide: An efficient anion exchange platform with enhanced diclofenac adsorption property.

    PubMed

    Hossein Beyki, Mostafa; Mohammadirad, Mosleh; Shemirani, Farzaneh; Saboury, Ali Akbar

    2017-02-10

    Polymeric ionomers with anion exchange capability are considered to be classes of environmentally friendly compounds as combination of them with anionic layered hydroxides constitute emerging advance materials. Biosorption by polymeric ionomer - layered double hydroxide (LDH) hybrid material exhibits an attractive green, low cost and low toxic - clean way. As a result, a novel anion exchange platform has been developed by the reaction of CaAl - LDH with Fe(2+), cellulose solution, epichlorohydrin and pyridine. Magnetite cellulose - LDH (MCL) and the ionomer were used for efficient biosorption of diclofenac sodium (DF). Results showed that ionomer has more efficiency for DF adsorption relative to MCL. Magnetite ionomer showed fast equilibrium time (2min) with maximum uptake of 268mgg(-1). Isotherm and Kinetic models were also studied. Regeneration of the sorbent was performed with a mixture of methanol -NaOH (2.0molL(-1)) solution.

  14. A dication cross-linked composite anion-exchange membrane for all-vanadium flow battery applications.

    PubMed

    Zhang, Fengxiang; Zhang, Huamin; Qu, Chao

    2013-12-01

    We report the fabrication and properties of a high-performance, inexpensive, composite, anion-exchange membrane (AEM) for an all-vanadium flow battery (VFB) application. The AEM was fabricated by dication cross-linking without the involvement of trimethylamine, and shows well-balanced anion conductivity and robustness due to imidazolium and imidazolium-ammonium functionalities, as well as a concomitantly achieved semi-interpenetrating network structure. The VFB single cell yielded a Coulombic efficiency of 99 % and an energy efficiency of 84 % at 80 mA cm(-2) , and operated for over 900 charge/discharge cycles. This work demonstrates the combined use of several favorable AEM design rationales, such as incorporating abundant and efficient anion-exchange groups, constructing a swelling- and oxidation-resistant structure, and facile fabrication; it provides an effective way of developing high-performance, low-cost AEMs for VFB applications.

  15. Solid phase extraction of lactic acid from fermentation broth by anion-exchangeable silica confined ionic liquids.

    PubMed

    Bi, Wentao; Zhou, Jun; Row, Kyung Ho

    2011-01-15

    Three anion-exchangeable, silica-confined ionic liquids were synthesized for solid phase extraction of lactic acid from fermentation broth, followed by high-performance liquid chromatography coupled to ultraviolet detection. By comparing the adsorption isotherms of lactic acid on different silica-confined ionic liquids, interactions between the lactic acid and sorbents were investigated. The adsorbed amounts were then fitted into different adsorption isotherm equations; finally, the Langmuir equation was selected. Then the imidazolium silica with the highest adsorption capacity of lactic acid was packed into a cartridge for solid phase extraction. The loading volume of the cartridge was optimized by the Langmuir equation and geometry. After washing with distilled water and eluting with 0.25 mol L(-1) of an HCl solution, the lactic acid was separated from interference with a recovery yield of 91.9%. Furthermore, this kind of anion-exchangeable material exhibited potential for industrial applications and separation of other anionic bioactive compounds.

  16. Preparation and Characterization of an Alkaline Anion Exchange Membrane from Chlorinated Poly(propylene) Aminated with Branched Poly(ethyleneimine)

    DTIC Science & Technology

    2013-01-01

    was produced through amination of chlorinated poly(propylene) (PP) with poly(ethyleneimine) (PEI) and quaternized with iodoethane. The synthesis of...PP) with poly(ethyleneimine) (PEI) and quaternized with iodoethane. The synthesis of the new polymer is confirmed by FTIR 1 H and 13 C NMR. The...Article history : Received 4 December 2012 Received in revised form 29 March 2013 Accepted 2 April 2013 Available online Keywords: Anion exchange

  17. Extraction of Carbon Dioxide From Seawater by Ion Exchange Resin. Part 2. Using Strong Base Anion Exchange Resin

    DTIC Science & Technology

    2009-09-29

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6180--09-9211 Extraction of Carbon Dioxide from Sea water by Ion Exchange Resin Part...STRONG BASE ANION EXCHANGE RESIN 1.0 BACKGROUND The Ocean Thermal Energy Conversion (OTEC) process converts solar thermal energy absorbed by the ocean...into electrical power [1,2]. During the OTEC process dissolved carbon dioxide (CO2) in ocean water is liberated as a gas. Since CO2 is implicated in

  18. Synthesis of blue-photoluminescent graphene quantum dots/polystyrenic anion-exchange resin for Fe(III) detection

    NASA Astrophysics Data System (ADS)

    Zhang, Wenjun; Gan, Jie

    2016-05-01

    A novel solid fluorescent sensor with millimeter size, based on graphene quantum dots/polystyrenic anion-exchange resin (GQDs/PS-AER) was obtained for the detection of Fe3+. The linear response range of Fe3+ was obtained from 1 μM to 7 μM and the detection limit was as low as 0.65 μM. In addition, the sensor could be regenerated by adding complexing agent EDTA and be separated by using simple filtration.

  19. Mass transfer of single- and double-charged anions through an MA-41L anion-exchange membrane

    SciTech Connect

    Kulikova, O.M.; Sharkova, O.V.; Kulikov, S.M.

    1995-02-20

    Selective anion transfer through an MA-41L anion-exchange membrane in the Cl{sup -}-F{sup -}, Cl{sup -}-SO{sub 4}{sup 2-}, F{sup -}-SO{sub 4}{sup 2-}, and F{sup -}-CO{sub 3}{sup 2-} systems has been studied. The feasibility of partial anion separation in the chloride-sulfate system has been demonstrated. The separation of fluoride ions from accompanying anions was found to be practically impossible.

  20. Macroporous poly(glycidyl methacrylate-triallyl isocyanurate-divinylbenzene) matrix as an anion-exchange resin for protein adsorption.

    PubMed

    Yu, Y; Sun, Y

    1999-09-03

    A novel macroporous poly(glycidyl methacrylate-triallyl isocyanurate-divinylbenzene) matrix was prepared by a radical suspension copolymerization. The matrix contained epoxy groups, so diethylaminohydroxypropyl groups were coupled to the matrix, leading to an anion-exchange resin. We studied the components, surface and pore structures of the anion-exchange resin by Fourier transform infared spectroscopy and scanning electron microscopy (SEM). SEM observations showed that the resin abounded in macropores as large as 3 to 8 microns both in the surface and the interior. The back-pressure of the column packed with the resin was modest even at a high flow-rate (60.2 cm/min). Then, bovine serum albumin (BSA) was used as a model protein to examine the adsorption properties of the anion-exchange resin. The results showed that under optimum conditions the resin had a capacity as high as 22.8 mg BSA/g wet resin, or 68.7 mg/g dry resin. The adsorbed protein could be desorbed by increasing the liquid phase ionic strength. Most importantly, the matrix had little nonspecific adsorption for BSA before introducing the ion-exchange groups.

  1. Human kidney anion exchanger 1 interacts with kinesin family member 3B (KIF3B)

    SciTech Connect

    Duangtum, Natapol; Junking, Mutita; Sawasdee, Nunghathai; Cheunsuchon, Boonyarit; Limjindaporn, Thawornchai; Yenchitsomanus, Pa-thai

    2011-09-16

    Highlights: {yields} Impaired trafficking of kAE1 causes distal renal tubular acidosis (dRTA). {yields} The interaction between kAE1 and kinesin family member 3B (KIF3B) is reported. {yields} The co-localization between kAE and KIF3B was detected in human kidney tissues. {yields} A marked reduction of kAE1 on the cell membrane was observed when KIF3B was knockdown. {yields} KFI3B plays an important role in trafficking of kAE1 to the plasma membrane. -- Abstract: Impaired trafficking of human kidney anion exchanger 1 (kAE1) to the basolateral membrane of {alpha}-intercalated cells of the kidney collecting duct leads to the defect of the Cl{sup -}/HCO{sub 3}{sup -} exchange and the failure of proton (H{sup +}) secretion at the apical membrane of these cells, causing distal renal tubular acidosis (dRTA). In the sorting process, kAE1 interacts with AP-1 mu1A, a subunit of AP-1A adaptor complex. However, it is not known whether kAE1 interacts with motor proteins in its trafficking process to the plasma membrane or not. We report here that kAE1 interacts with kinesin family member 3B (KIF3B) in kidney cells and a dileucine motif at the carboxyl terminus of kAE1 contributes to this interaction. We have also demonstrated that kAE1 co-localizes with KIF3B in human kidney tissues and the suppression of endogenous KIF3B in HEK293T cells by small interfering RNA (siRNA) decreases membrane localization of kAE1 but increases its intracellular accumulation. All results suggest that KIF3B is involved in the trafficking of kAE1 to the plasma membrane of human kidney {alpha}-intercalated cells.

  2. Physical and functional links between anion exchanger-1 and sodium pump.

    PubMed

    Su, Ya; Al-Lamki, Rafia S; Blake-Palmer, Katherine G; Best, Alison; Golder, Zoe J; Zhou, Aiwu; Karet Frankl, Fiona E

    2015-02-01

    Anion exchanger-1 (AE1) mediates chloride-bicarbonate exchange across the plasma membranes of erythrocytes and, via a slightly shorter transcript, kidney epithelial cells. On an omnivorous human diet, kidney AE1 is mainly active basolaterally in α-intercalated cells of the collecting duct, where it is functionally coupled with apical proton pumps to maintain normal acid-base homeostasis. The C-terminal tail of AE1 has an important role in its polarized membrane residency. We have identified the β1 subunit of Na(+),K(+)-ATPase (sodium pump) as a binding partner for AE1 in the human kidney. Kidney AE1 and β1 colocalized in renal α-intercalated cells and coimmunoprecipitated (together with the catalytic α1 subunit of the sodium pump) from human kidney membrane fractions. ELISA and fluorescence titration assays confirmed that AE1 and β1 interact directly, with a Kd value of 0.81 μM. GST-AE1 pull-down assays using human kidney membrane proteins showed that the last 11 residues of AE1 are important for β1 binding. siRNA-induced knockdown of β1 in cell culture resulted in a significant reduction in kidney AE1 levels at the cell membrane, whereas overexpression of kidney AE1 increased cell surface sodium pump levels. Notably, membrane staining of β1 was reduced throughout collecting ducts of AE1-null mouse kidney, where increased fractional excretion of sodium has been reported. These data suggest a requirement of β1 for proper kidney AE1 membrane residency, and that activities of AE1 and the sodium pump are coregulated in kidney.

  3. Separation of boric acid in liquid waste with anion exchange membrane contactor

    SciTech Connect

    Park, J.K.; Lee, K.J.

    1995-12-31

    In order to separate boric acid in liquid waste, some possible technologies were investigated and the membrane contactor without dispersion and density differences was selected. The separation experiments on a Celgard 3401{reg_sign} hydrophilic microporous membrane contactor were first performed to obtain the basic data and to determine the properties of the contactor. The experimental conditions were as follows: boric acid concentrations up to 2.0 M, pH 7.0, temperatures of 25 and 55 C, and flow rates of 100, 300, 500, and 800 cm{sup 3}/min. Secondly, an AFN{reg_sign} anion exchange membrane contactor was tested at temperatures of 40 and 55 C and flow rate 400 cm{sup 3}/min. Boric acid solutions were prepared by the same method as that for Celgard 3401{reg_sign} but contained 5.0{times}10{sup {minus}4} M cobalt chloride (CoCl{sub 2}). To simulate membrane contractors, parameters such as the differential diffusion coefficients of boric acid and the mass transfer coefficients in the AFN membrane were measured, and regression models estimating the diffusion coefficient at several conditions were developed. The Celgard 3401{reg_sign} membrane contactor was simulated and compared with experimental data. Simulation results agreed with the experimental data well when a proper correction factor was utilized. The correction factor was independent of the solution temperature and was 8.75 at the flow rates of 300--800 cm{sup 3}/min. This correction factor was also applied to simulate the AFN{reg_sign} resulted in a good agreement with experiment at 40 C, but not 55 C. The retention on cobalt was also better at 40 c than 55 C. The simulating computer program was also applied to a life size contactor designed conceptually.

  4. Studies on the batch adsorption of plasmid DNA onto anion-exchange chromatographic supports.

    PubMed

    Ferreira, G N; Cabral, J M; Prazeres, D M

    2000-01-01

    The adsorption of a supercoiled 4.8 kbp plasmid onto quaternary ammonium anion-exchangers was studied in a finite bath. Equilibrium experiments were performed with pure plasmid, at 25 degrees C, using commercial Q-Sepharose matrices differing in particle diameter (High Performance, 34 microm; Fast Flow, 90 microm; and Big Beads, 200 microm) and a recently commercialized ion-exchanger, Streamline QXL (d(p) = 200 microm) at different salt concentrations (0.5, 0.7, and 1 M NaCl). Plasmid adsorption was found to follow second-order kinetics (Langmuir isotherm) with average association constants K(A) = 0.32+/-0.12 mL microg(-)(1) and K(A) = 0.25+/-0.15 mL microg(-1) at 0.5 and 0.7 M Nacl, respectively. The maximum binding capacities were not dependent on the ionic strength in the range 0.5-0.7 M but decreased with increasing particle diameter, suggesting that adsorption mainly occurs at the surface of the particles. No adsorption was found at 1 M NaCl. A nonporous model was applied to describe the uptake rate of plasmid onto Streamline QXL at 0.5 M NaCl. The overall process rate was controlled by mass transfer in the regions of low relative amounts of adsorbent (initial stages) and kinetically controlled in the later stages of the process for high relative amounts of adsorbent. The forward reaction rate constant (k(1) = 0.09+/-0.01 mL mg(-1) s(-1)) and film mass transfer coefficient (K(f) = (6 +/- 2) x 10(-4) cm s(-1)) were calculated. Simulations were performed to study the effect of the relative amount of adsorbent on the overall process rate, yield, and media capacity utilization.

  5. Anion exchange SPE and liquid chromatography-tandem mass spectrometry in GHB analysis.

    PubMed

    Elian, Albert A; Hackett, Jeffery

    2011-12-01

    In this study, the extraction of γ-hydroxybutyrate (GHB) from urine using solid-phase extraction (SPE) is described. SPE was performed on anion exchange columns after samples of urine had been diluted with de-ionized water. After application of the diluted samples containing GHB-d(6) as an internal standard, the sorbent was washed with deionized water and methanol and dried. The GHB was eluted from the SPE column with a solvent consisting of methanol containing 6% glacial acetic acid. The eluent was collected, evaporated to dryness, and dissolved in mobile phase (100 μL) for analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in negative multiple reaction monitoring (MRM) mode. Liquid chromatography was performed in gradient mode employing a biphenyl column and a mobile phase consisting of acetontitrile (containing 0.1% formic acid) and 0.1% aqueous formic acid. The total run time for each analysis was less than 5 min. The limits of detection/quantification for this method were determined to be 50 and 100 ng/mL, respectively. The method was found to be linear from 500 ng/mL to 10,000 ng/mL (r(2)>0.995). The recovery of GHB was found to be greater than 75%. In this report, results of authentic urine samples analyzed for GHB by this method are presented. GHB concentrations in these samples were found to be range from less than 500 ng/mL to 5110 ng/mL.

  6. Removing hexavalent chromium from subsurface waters with anion-exchange resin

    SciTech Connect

    Torres, R.A.

    1995-06-01

    Some subsurface waters at Lawrence Livermore National Laboratory (LLNL) are contaminated with volatile organic compounds (VOCs). Hexavalent chromium, Cr(VI), is also present in the ground water; however, the source of the Cr(VI) may be natural. The Cr(VI) still must be treated if brought to the surface because its concentration exceeds discharge standards. We are planning facilities for removing the VOCs and Cr(VI) to a level below the discharge standards. The planned treatment includes the following steps: (1) Pumping the water to the surface facility. (2) Purging the VOCs with air and absorbing them on activated carbon. The VOCs in LLNL`s subsurface waters are primarily chlorinated organic solvents, such as dichloroethylene (DCE), trichloroethylene (TCE), perchloroethylene (PCE), and chloroform (CHCl{sub 3}). Contamination levels range from tens to thousands of parts per billion. (3) Filtering the water. (4) Passing the water through anion-exchange resin to remove the Cr. The Cr in LLNL subsurface waters occurs almost entirely as Cr(VI), which exists as the chromate anion, CrO{sub 4}{sup 2-}, at environmental pH. Cr levels range from tens to hundreds of parts per billion. (5) Discharging the treated water into the local arroyos. The relevant discharge criteria are 5 ppb total VOCs, 11 ppb Cr(VI), and pH between 6.5 and 8.5, inclusive. This report describes laboratory experiments undertaken to learn how the proposed treatment facility can be expected to operate. The laboratory results are expected to supply vendors with the detailed performance specifications needed to prepare bids on the Cr removal portion of the treatment facility. The treatment facility is expected to process 60 gallons per minute (gpm) of water by stripping VOCs with 720 standard cubic feet per minute (scfm) of air and removing Cr(VI) with 60 ft{sup 3} of resin.

  7. Selective removal of phosphate from wastewater using hydrated metal oxides dispersed within anionic exchange media.

    PubMed

    Acelas, Nancy Y; Martin, Benjamin D; López, Diana; Jefferson, Bruce

    2015-01-01

    Hydrated ferric oxide (HFeO), hydrated zirconium oxide (HZrO) and hydrated copper oxide (HCuO) were immobilized within a microporous anion exchange resin (IRA-400), forming hybrid media for enhanced phosphate removal from aqueous systems. Empirical data from batch kinetic trials fitted the pseudo second order mechanism for chemical adsorption and each media was rate limited by intraparticle diffusion overall. These models were also used to predict the adsorption rate constants and the equilibrium adsorption capacities, which ranged from 26.51 to 30.44 mgP g(-1), and from 24.15 to 27.90 mgP g(-1) of media for the calculated and experimental capacities, respectively. The phosphate adsorption behavior by the hybrid materials fit both the Langmuir and Freundlich adsorption isotherms (R(2)>0.94), and the maximum adsorption capacities were 111.1 mgP g(-1) for HFeO, 91.74 mgP g(-1) for HZrO and 74.07 mgP g(-1) for HCuO. The effect of competing ions such as sulfate reduced these capacities to 18.52 mgP g(-1) for HFeO and 18.97 mgP g(-1) for HZrO. Despite this decrease, HFeO was capable of reducing the phosphate in a real wastewater matrix by 83%, and the HZrO media was able to reduce it by 86%, suggesting that such hybrid media have the potential for application at full scale.

  8. Anion Exchanger 2 Regulates Dectin-1-Dependent Phagocytosis and Killing of Candida albicans

    PubMed Central

    Urso, Katia; Charles, Julia F.; Shull, Gary E.; Aliprantis, Antonios O.; Balestrieri, Barbara

    2016-01-01

    Anion exchanger 2 (Ae2; gene symbol, Slc4a2) is a plasma membrane Cl-/HCO3- exchanger expressed in the gastrointestinal tract, kidney and bone. We have previously shown that Ae2 is required for the function of osteoclasts, bone resorbing cells of the macrophage lineage, to maintain homeostatic cytoplasmic pH and electroneutrality during acid secretion. Macrophages require endosomal acidification for pathogen killing during the process known as phagocytosis. Chloride is thought to be the principal ion responsible for maintaining electroneutrality during organelle acidification, but whether Cl-/HCO3- exchangers such as Ae2 contribute to macrophage function is not known. In this study we investigated the role of Ae2 in primary macrophages during phagocytosis. We find that Ae2 is expressed in macrophages where it regulates intracellular pH and the binding of Zymosan, a fungal cell wall derivative. Surprisingly, the transcription and surface expression of Dectin-1, the major phagocytic receptor for Candida albicans (C. albicans) and Zymosan, is reduced in the absence of Ae2. As a consequence, Zymosan-induced Tnfα expression is also impaired in Ae2-deficient macrophages. Similar to Ae2 deficiency, pharmacological alkalinization of lysosomal pH with bafilomycin A decreases both Dectin-1 mRNA and cell surface expression. Finally, Ae2-deficient macrophages demonstrate defective phagocytosis and killing of the human pathogenic fungus C. albicans. Our results strongly suggest that Ae2 is a critical factor in the innate response to C. albicans. This study represents an important contribution to a better understanding of how Dectin-1 expression and fungal clearance is regulated. PMID:27391897

  9. Towards high conductivity in anion-exchange membranes for alkaline fuel cells.

    PubMed

    Li, Nanwen; Guiver, Michael D; Binder, Wolfgang H

    2013-08-01

    Quaternized poly(2,6-dimethylphenylene oxide) materials (PPOs) containing clicked 1,2,3-triazoles were first prepared through Cu(I) -catalyzed "click chemistry" to improve the anion transport in anion-exchange membranes (AEMs). Clicked 1,2,3-triazoles incorporated into AEMs provided more sites to form efficient and continuous hydrogen-bond networks between the water/hydroxide and the triazole for anion transport. Higher water uptake was observed for these triazole membranes. Thus, the membranes showed an impressive enhancement of the hydroxide diffusion coefficient and, therefore, the anion conductivities. The recorded hydroxide conductivity was 27.8-62 mS cm(-1) at 20 °C in water, which was several times higher than that of a typical PPO-based AEM (TMA-20) derived from trimethylamine (5 mS cm(-1) ). Even at reduced relative humidity, the clicked membrane showed superior conductivity to a trimethylamine-based membrane. Moreover, similar alkaline stabilities at 80 °C in 1 M NaOH were observed for the clicked and non-clicked membranes. The performance of a H2 /O2 single cell assembled with a clicked AEM was much improved compared to that of a non-clicked TMA-20 membrane. The peak power density achieved for an alkaline fuel cell with the synthesized membrane 1a(20) was 188.7 mW cm(-2) at 50 °C. These results indicated that clicked AEM could be a viable strategy for improving the performance of alkaline fuel cells.

  10. Chemical separation of Mo and W from terrestrial and extraterrestrial samples via anion exchange chromatography.

    PubMed

    Nagai, Yuichiro; Yokoyama, Tetsuya

    2014-05-20

    A new two-stage chemical separation method was established using an anion exchange resin, Eichrom 1 × 8, to separate Mo and W from four natural rock samples. First, the distribution coefficients of nine elements (Ti, Fe, Zn, Zr, Nb, Mo, Hf, Ta, and W) under various chemical conditions were determined using HCl, HNO3, and HF. On the basis of the obtained distribution coefficients, a new technique for the two-stage chemical separation of Mo and W, along with the group separation of Ti-Zr-Hf, was developed as follows: 0.4 M HCl-0.5 M HF (major elements), 9 M HCl-0.05 M HF (Ti-Zr-Hf), 9 M HCl-1 M HF (W), and 6 M HNO3-3 M HF (Mo). After the chemical procedure, Nb remaining in the W fraction was separated using 9 M HCl-3 M HF. On the other hand, Nb and Zn remaining in the Mo fraction were removed using 2 M HF and 6 M HCl-0.1 M HF. The performance of this technique was evaluated by separating these elements from two terrestrial and two extraterrestrial samples. The recovery yields for Mo, W, Zr, and Hf were nearly 100% for all of the examined samples. The total contents of the Zr, Hf, W, and Mo in the blanks used for the chemical separation procedure were 582, 9, 29, and 396 pg, respectively. Therefore, our new separation technique can be widely used in various fields of geochemistry, cosmochemistry, and environmental sciences and particularly for multi-isotope analysis of these elements from a single sample with significant internal isotope heterogeneities.

  11. Palmitoylation is not required for trafficking of human anion exchanger 1 to the cell surface.

    PubMed Central

    Cheung, Joanne C; Reithmeier, Reinhart A F

    2004-01-01

    AE1 (anion exchanger 1) is a glycoprotein found in the plasma membrane of erythrocytes, where it mediates the electroneutral exchange of chloride and bicarbonate, a process important in CO2 removal from tissues. It had been previously shown that human AE1 purified from erythrocytes is covalently modified at Cys-843 in the membrane domain with palmitic acid. In this study, the role of Cys-843 in human AE1 trafficking was investigated by expressing various AE1 and Cys-843Ala (C843A) mutant constructs in transiently transfected HEK-293 cells. The AE1 C843A mutant was expressed to a similar level to AE1. The rate of N-glycan conversion from high-mannose into complex form in a glycosylation mutant (N555) of AE1 C843A, and thus the rate of trafficking from the endoplasmic reticulum to the Golgi, were comparable with that of AE1 (N555). Like AE1, AE1 C843A could be biotinylated at the cell surface, indicating that a cysteine residue at position 843 is not required for cell-surface expression of the protein. The turnover rate of AE1 C843A was not significantly different from AE1. While other proteins could be palmitoylated, labelling of transiently transfected HEK-293 cells or COS7 cells with [3H]palmitic acid failed to produce any detectable AE1 palmitoylation. These results suggest that AE1 is not palmitoylated in HEK-293 or COS7 cells and can traffic to the plasma membrane. PMID:14640982

  12. New Anion-Exchange Resins for Improved Separations of Nuclear Materials

    SciTech Connect

    Bartsch, Richard A.; Barr, Mary E.

    2001-04-30

    Improved separations of nuclear materials will have a significant impact upon a broad range of DOE activities. DOE-EM Focus Areas and Crosscutting Programs have identified improved methods for the extraction and recovery of radioactive metal ions from process, waste, and environmental waters as critical needs for the coming years. We propose to develop multifunctional anion-exchange resins that facilitate anion uptake by carefully controlling the structure of the anion receptor site. Our new ion-exchange resins interface the field of ion-specific chelating ligands with robust, commercial ion-exchange technology to provide materials which exhibit superior selectivity and kinetics of sorption and desorption. The following Focus Areas and Crosscutting Programs have described needs that would be favorably impacted by the new material: Efficient Separations and Processing - radionuclide removal from aqueous phases; Plutonium - Pu, Am or total alpha removal to meet regulatory requirement s before discharge to the environment; Plumes - U and Tc in groundwater, U, Pu, Am, and Tc in soils; Mixed Waste - radionuclide partitioning; High-Level Tank Waste - actinide and Tc removal from supernatants and/or sludges. The basic scientific issues which need to be addressed are actinide complex speciation along with modeling of metal complex/functional site interactions in order to determine optimal binding-site characteristics. Synthesis of multifunctionalized extractants and ion-exchange materials that implement key features of the optimized binding site, and testing of these materials, will provide feedback to the modeling and design activities. Resin materials which actively facilitate the uptake of actinide complexes from solution should display both improved selectivity and kinetic properties. The long-range implications of this research, however, go far beyond the nuclear complex. This new methodology of ''facilitated uptake'' could revolutionize ion-exchange technology

  13. Tailor-made anion-exchange membranes for salinity gradient power generation using reverse electrodialysis.

    PubMed

    Guler, Enver; Zhang, Yali; Saakes, Michel; Nijmeijer, Kitty

    2012-11-01

    Reverse electrodialysis (RED) or blue energy is a non-polluting, sustainable technology for generating power from the mixing of solutions with different salinity, that is, seawater and river water. A concentrated salt solution (e.g., seawater) and a diluted salt solution (e.g., river water) are brought into contact through an alternating series of polymeric anion-exchange membranes (AEMs) and cation-exchange membranes (CEMs), which are either selective for anions or cations. Currently available ion-exchange membranes are not optimized for RED, whereas successful RED operation notably depends on the used ion-exchange membranes. We designed such ion-exchange membranes and for the first time we show the performance of tailor-made membranes in RED. More specifically, we focus on the development of AEMs because these are much more complex to prepare. Herein we propose a safe and more environmentally friendly method and use halogenated polyethers, such as polyepichlorohydrin (PECH) as the starting material. A tertiary diamine (1,4-diazabicyclo[2.2.2]octane, DABCO) was used to introduce the ion-exchange groups by amination and for simultaneous cross-linking of the polymer membrane. Area resistances of the series of membranes ranged from 0.82 to 2.05 Ω cm² and permselectivities from 87 to 90 %. For the first time we showed that tailor-made ion-exchange membranes can be applied in RED. Depending on the properties and especially membrane thickness, application of these membranes in RED resulted in a high power density of 1.27 W m⁻², which exceeds the power output obtained with the commercially available AMX membranes. This shows the potential of the design of ion-exchange membranes for a viable blue energy process.

  14. Adsorption of polyethylene-glycolated bovine serum albumin on macroporous and polymer-grafted anion exchangers.

    PubMed

    Zhu, Mimi; Carta, Giorgio

    2014-01-24

    The chromatographic and adsorptive properties of BSA and BSA conjugated with 10 and 30kDa PEG polymers are determined for a macroporous anion exchanger (UNOsphere™ Diol Q) and for a polymer-grafted material having the same backbone matrix (Nuvia Q™). Chromatographic retention, adsorption capacity, and adsorption kinetics are enhanced in the polymer-grafted resin for both BSA and 10kDa PEG-BSA as a result of interactions with the grafted polymers. However, the difference between the two resins diminishes for 30kDa PEG-BSA indicating that size exclusion effects strongly affect binding in the polymer-grafted material for this larger conjugate. Images of intraparticle concentration profiles obtained by confocal scanning laser microscopy show that the transport mechanisms of both BSA and PEGylated BSA are very different in the two resins. The protein binding kinetics are dominated by ordinary pore diffusion and are essentially independent of the direction of transport for UNOsphere Diol Q as a result of its large pore size. Thus, for this material, displacement of PEGylated BSA by BSA is clearly evident at the intraparticle scale. On the other hand, the protein binding kinetics in Nuvia Q are consistent with a solid diffusion mechanism driven by the adsorbed protein concentration. For this material, protein transport is very fast for one component or two-component co-adsorption of BSA and PEGylated BSA but slows down dramatically for sequential adsorption of these species as a result of heightened diffusional hindrance when the two components counterdiffuse within the resin.

  15. A Robust and Fully-Automated Chromatographic Method for the Quantitative Purification of Ca and Sr for Isotopic Analysis

    NASA Astrophysics Data System (ADS)

    Smith, H. B.; Kim, H.; Romaniello, S. J.; Field, P.; Anbar, A. D.

    2014-12-01

    High throughput methods for sample purification are required to effectively exploit new opportunities in the study of non-traditional stable isotopes. Many geochemical isotopic studies would benefit from larger data sets, but these are often impractical with manual drip chromatography techniques, which can be time-consuming and demand the attention of skilled laboratory staff. Here we present a new, fully-automated single-column method suitable for the purification of both Ca and Sr for stable and radiogenic isotopic analysis. The method can accommodate a wide variety of sample types, including carbonates, bones, and teeth; silicate rocks and sediments; fresh and marine waters; and biological samples such as blood and urine. Protocols for these isotopic analyses are being developed for use on the new prepFAST-MCTM system from Elemental Scientific (ESI). The system is highly adaptable and processes up to 24-60 samples per day by reusing a single chromatographic column. Efficient column cleaning between samples and an all Teflon flow path ensures that sample carryover is maintained at the level of background laboratory blanks typical for manual drip chromatography. This method is part of a family of new fully-automated chromatographic methods being developed to address many different isotopic systems including B, Ca, Fe, Cu, Zn, Sr, Cd, Pb, and U. These methods are designed to be rugged and transferrable, and to allow the preparation of large, diverse sample sets via a highly repeatable process with minimal effort.

  16. Automated high-throughput purification of genomic DNA from whole blood using Promega's MagneSilTM paramagnetic particles with either the Max Yield or MagneSilTM ONE normalized purification methods

    NASA Astrophysics Data System (ADS)

    Bitner, Rex M.; Koller, Susan C.; Sankbeil, Jacqui

    2003-07-01

    Two different methods of automated high throughput purification of genomic DNA from human whole blood in 96 well plates are described. One method uses MagneSilTM paramagnetic particles to purify a maximal amount of the DNA present in the sample. Another method, the MagnesilTM ONE system, allows for the purification of a predetermined amount of DNA from human whole blood. Protocols for the purification of 100 ng or, alternatively 1 ug, of human genomic DNA from whole blood using MagneSilTM paramagnetic particles and a Beckman BioMekTM FX robot are described. With the maximal yield purification system, typical DNA yields fall in the range of 4-9 ug of DNA from 200ul of human whole blood, depending upon the white cell content of donor sample. For situations where DNA achiving is desired, or when the number of downstream sample applications is not clearly defined (e.g. multiple SNP analyses) the maximal yield method is usually preferred. However, in situations with a defined downstream application (e.g. criminal databasing or use of a defined set of amplifications) where purifying DNA in a narrow concentrate range streamlines the high throughput purification and analysis process, the automated MagneSilTM ONE purification system is the method of choice. DNA from either method is suitable for applications such as PCR, STR, READITTM SNP analysis, and multiplexed PCR systems such as Promega's Y-chromosome deletion detection system.

  17. Selective Anion Exchange Resins for the Removal of Perchlorate [(CIO{sub 4}{sup -})] from Groundwater

    SciTech Connect

    Gu, B.

    1999-05-20

    The primary objective of this project was to evaluate a novel bifunctional anion exchange resin for the cost-effective, in situ treatment of groundwater contaminated with perchlorate (ClO{sub 4}{sup -}). Both laboratory and field studies were performed to determine the selectivity and capacity of the bifunctional synthetic resins to sorb ClO{sub 4}{sup -} from simulated or actual contaminated groundwater. A number of synthetic bifunctional resins, including two commercial versions made by Purolite International and three commercially available, mono-functional resins, were tested. Initial laboratory batch and column breakthrough studies determined the best synthetic resins and the optimal conditions for the field experiment. Laboratory results indicated that the bifunctional synthetic resins, D-3696 and RO-02-119 were highly selective toward ClO{sub 4}{sup -} and performed {approx}5 times better than the best commercial nitrate resin (Purolite{reg_sign} A-520E) and more than an order of magnitude better than some nonselective commercial resins (e.g. Amberlite{reg_sign} IRA-900). The bifunctional resins were particularly effective in removing trace quantities of ClO{sub 4}{sup -} in groundwater to below the detection limit ({approx} 3 {micro}g/L). A field trial demonstrated that the bifunctional resin (D-3696) was able to treat {approx} 110,000 bed volumes of groundwater before a 10% breakthrough of ClO{sub 4}{sup -} occurred under the column flow-through conditions (running at {approx} 2 bed volumes per minute). On the other hand, the Purolite{reg_sign} A-520E resin was able to treat {approx} 23,000 bed volumes of groundwater under the same experimental conditions. No pretreatment was needed to remove either dissolved organic matter or other competing anions (such as SO{sub 4}{sup 2-} or NO{sub 3}{sup -}) in the groundwater, and the treatment process did not alter the water quality by removing or adding secondary by-products because of the high selectivity of the

  18. Understanding ion and solvent transport in anion exchange membranes under humidified conditions

    NASA Astrophysics Data System (ADS)

    Sarode, Himanshu

    Anion exchange membranes (AEM) have been studied for more than a decade for potential applications in low temperature fuel cells and other electrochemical devices. They offer the advantage of faster reaction kinetics under alkaline conditions and ability to perform without costly platinum catalyst. Inherently slow diffusion of hydroxide ions compared to protons is a primary reason for synthesizing and studying the ion transport properties in AEMs. The aim of this thesis is to understand ion transport in novel AEMs using Pulse Gradient stimulated Spin Echo Nuclear Magnetic Resonance technique (PGSE NMR), water uptake, ionic conductivity, Small Angle X-ray Scattering (SAXS) etc. All experiments were performed under humidified conditions (80--95% relative humidity) and fuel cell operating temperatures of 30--90°C. In this work, the NMR tube design was modified for humidifying the entire NMR tube evenly from our previous design. We have developed a new protocol for replacing caustic hydroxide with harmless fluoride or bicarbonate ions for 19F and 13 C NMR diffusion experiments. After performing these NMR experiments, we have obtained in-depth understanding of the morphology linked ion transport in AEMs. We have obtained the highest fluoride self-diffusion coefficient of > 1 x 10-5 cm2/sec ( 55°C) for ETFE-g-PVBTMA membrane which is a result of low tortuosity of 1 obtained for the membrane. This faster fluoride transport combined with low tortuosity of the membrane resulted in > 100mS/cm hydroxide conductivity for the membrane. Polycyclooctene (PCOE) based triblock copolymers are also studied for in-depth understanding of molecular weight, IEC, mechanical and transport properties. Effect of melting temperature of PCOE has favorable effect on increasing ion conductivity and lowering activation energy. Mechanical properties of these types of membranes were studied showing detrimental effect of water plasticization which results in unsuitable mechanical properties

  19. Strategies for automated sample preparation, nucleic acid purification, and concentration of low-target-number nucleic acids in environmental and food processing samples

    NASA Astrophysics Data System (ADS)

    Bruckner-Lea, Cynthia J.; Holman, David A.; Schuck, Beatrice L.; Brockman, Fred J.; Chandler, Darrell P.

    1999-01-01

    The purpose of this work is to develop a rapid, automated system for nucleic acid purification and concentration from environmental and food processing samples. Our current approach involves off-line filtration and cell lysis (ballistic disintegration) functions in appropriate buffers followed by automated nucleic acid capture and purification on renewable affinity matrix microcolumns. Physical cell lysis and renewable affinity microcolumns eliminate the need for toxic organic solvents, enzyme digestions or other time- consuming sample manipulations. Within the renewable affinity microcolumn, we have examined nucleic acid capture and purification efficiency with various microbead matrices (glass, polymer, paramagnetic), surface derivitization (sequence-specific capture oligonucleotides or peptide nucleic acids), and DNA target size and concentration under variable solution conditions and temperatures. Results will be presented comparing automated system performance relative to benchtop procedures for both clean (pure DNA from a laboratory culture) and environmental (soil extract) samples, including results which demonstrate 8 minute purification and elution of low-copy nucleic acid targets from a crude soil extract in a form suitable for PCR or microarray-based detectors. Future research will involve the development of improved affinity reagents and complete system integration, including upstream cell concentration and cell lysis functions and downstream, gene-based detectors. Results of this research will ultimately lead to improved processes and instrumentation for on-line, automated monitors for pathogenic micro-organisms in food, water, air, and soil samples.

  20. Anion exchange of organic carboxylate by soils responsible for positive Km-fc relationship from methanol mixture.

    PubMed

    Kim, Minhee; Han, Junho; Hyun, Seunghun

    2013-09-01

    The cosolvency model was not applicable for predicting the sorption of organic carboxylic acids. The reason of inapplicability was investigated by analyzing the solubility (Sm) and sorption (Km) of benzoic acid, 2,4-dichlorophenoxyacetic acid (2,4-D), and 2,4,6-trichlorophenol (2,4,6-TCP). The Sm and Km by two iron-rich soils was measured as a function of methanol volume fraction (fc), electrolyte compositions, and pH(app). For 2,4,6-TCP, the Km of both neutral and anion species was well-explainable by the cosolvency model, exemplifying the knowledge of cosolvency power (σ) being sufficient to describe its sorption. However, for benzoic acid and 2,4-D, the Km of organic anions increased with fc, illustrating the organic carboxylate to be responsible for the deviation. The Sm of organic anions was not affected by the ionic valence (Ca(2+) vs. K(+)) of liquid phase. Among hydrophilic quantities of the 2,4-D sorption, the fraction of anion exchange increased with fc while the fraction of Ca-bridge decreased in the same range. Adding solvent in soil-water system is likely to render soil surface charge more positive, fortifying the anion exchange, but opposing the formation of Ca-bridging. Therefore, it can be concluded that the positive Km-fc relationship is due to the anion exchange of organic carboxylate with positively charged soil surface, whose contribution is >50% of overall sorption at solvent-free system and becomes greater with fc up to 82%.

  1. Evidence for the presence of three different anion exchangers in a red cell. Functional expression studies in Xenopus oocytes.

    PubMed

    Guizouarn, H; Musch, M W; Goldstein, L

    2003-05-15

    Anion exchangers (AE) are transmembrane proteins catalyzing electroneutral exchange of Cl(-) for HCO3-. To date, three different genes coding for this protein, AE1, AE2 and AE3, have been identified in many species. AE1 is considered to be the unique anion exchanger expressed in erythrocytes. In this paper we propose the presence of three different AEs in skate erythrocytes, a skAE1, a skAE2 and a skAE3, cloned by RT-PCR (reverse-transcriptase polymerase chain reaction). These three skAE have a similar predicted secondary structure. All three skAE are divided in two main domains: a hydrophilic cytoplasmic N-terminal domain and a C-terminal domain crossing the lipid bilayer at least 12 times. The greatest similarity is found in the membrane-spanning domain of the three skAE. The size as well as the amino-acid sequence of the cytoplasmic domain differ significantly among three anion exchangers. Functional expression studies in Xenopus oocytes led to the conclusion that skAE-1 and -2 share some functional features (Cl-dependence and DIDS sensitivity). The skAE3 could not be expressed in Xenopus oocytes. These data are in agreement with expression data obtained with AEs of different species utilizing the oocyte system. It is highly probable that these three new AE sequences come from three different genes, thus suggesting for the first time the presence of the three AE genes in Chondrichthyes.

  2. Role of anion exchangers in Cl- and HCO3- secretion by the human airway epithelial cell line Calu-3.

    PubMed

    Kim, Dusik; Kim, Juyeon; Burghardt, Beáta; Best, Len; Steward, Martin C

    2014-07-15

    Despite the importance of airway surface liquid pH in the lung's defenses against infection, the mechanism of airway HCO3- secretion remains unclear. Our aim was to assess the contribution of apical and basolateral Cl-/HCO3- exchangers to Cl- and HCO3- transport in the Calu-3 cell line, derived from human airway submucosal glands. Changes in intracellular pH (pHi) were measured following substitution of Cl- with gluconate. Apical Cl- substitution led to an alkalinization in forskolin-stimulated cells, indicative of Cl-/HCO3- exchange. This was unaffected by the anion exchange inhibitor DIDS but inhibited by the CFTR blocker CFTRinh-172, suggesting that the HCO3- influx might occur via CFTR, rather than a solute carrier family 26 (SLC26) exchanger, as recently proposed. The anion selectivity of the recovery process more closely resembled that of CFTR than an SLC26 exchanger, and quantitative RT-PCR showed only low levels of SLC26 exchanger transcripts relative to CFTR and anion exchanger 2 (AE2). For pHi to rise to observed values (∼7.8) through HCO3- entry via CFTR, the apical membrane potential must reverse to at least +20 mV following Cl- substitution; this was confirmed by perforated-patch recordings. Substitution of basolateral Cl- evoked a DIDS-sensitive alkalinization, attributed to Cl-/HCO3- exchange via AE2. This appeared to be abolished in forskolin-stimulated cells but was unmasked by blocking apical efflux of HCO3- via CFTR. We conclude that Calu-3 cells secrete HCO3- predominantly via CFTR, and, contrary to previous reports, the basolateral anion exchanger AE2 remains active during stimulation, providing an important pathway for basolateral Cl- uptake.

  3. Production of 61Cu using natural cobalt target and its separation using ascorbic acid and common anion exchange resin.

    PubMed

    Das, Sujata Saha; Chattopadhyay, Sankha; Barua, Luna; Das, Malay Kanti

    2012-02-01

    (61)Cu was produced by (nat)Co(α, xn)(61)Cu reaction. (61)Cu production yield was 89.5 MBq/μAh (2.42 mCi/μAh) at the end of irradiation (EOI). A simple radiochemical separation method using anion exchange resin and ascorbic acid has been employed to separate the product radionuclide from inactive target material and co-produced non-isotopic impurities. The radiochemical separation yield was about 90%. Radiochemical purity of (61)Cu was >99% 1 h after EOI. Final product was suitable for making complex with N(2)S(2) type of ligands.

  4. Anion-exchange high-performance liquid chromatography with conductivity detection for the analysis of phytic acid in food.

    PubMed

    Talamond, P; Doulbeau, S; Rochette, I; Guyot, J P

    2000-02-25

    A sensitive method for the accurate determination of phytic acid in food samples is described. The proposed procedure involves the anion-exchange liquid chromatography with conductivity detection. Initially, two methods of determination of phytic acid were compared: absorptiometry and high-performance ion chromatography (HPIC) with chemically suppressed conductivity detector. Unlike most conventional methods involving precipitation by FeCl3, the simpler and more reliable HPIC assay avoids the numerous assumptions inherent in the iron precipitation and the accuracy is independent of the phytate content. The protocol was also applied to a survey of phytic acid concentration in some cereal, oil and legume seeds.

  5. Flavourzyme, an Enzyme Preparation with Industrial Relevance: Automated Nine-Step Purification and Partial Characterization of Eight Enzymes.

    PubMed

    Merz, Michael; Eisele, Thomas; Berends, Pieter; Appel, Daniel; Rabe, Swen; Blank, Imre; Stressler, Timo; Fischer, Lutz

    2015-06-17

    Flavourzyme is sold as a peptidase preparation from Aspergillus oryzae. The enzyme preparation is widely and diversely used for protein hydrolysis in industrial and research applications. However, detailed information about the composition of this mixture is still missing due to the complexity. The present study identified eight key enzymes by mass spectrometry and partially by activity staining on native polyacrylamide gels or gel zymography. The eight enzymes identified were two aminopeptidases, two dipeptidyl peptidases, three endopeptidases, and one α-amylase from the A. oryzae strain ATCC 42149/RIB 40 (yellow koji mold). Various specific marker substrates for these Flavourzyme enzymes were ascertained. An automated, time-saving nine-step protocol for the purification of all eight enzymes within 7 h was designed. Finally, the purified Flavourzyme enzymes were biochemically characterized with regard to pH and temperature profiles and molecular sizes.

  6. Disposable and removable nucleic acid extraction and purification cartridges for automated flow-through systems

    DOEpatents

    Regan, John Frederick

    2014-09-09

    Removable cartridges are used on automated flow-through systems for the purpose of extracting and purifying genetic material from complex matrices. Different types of cartridges are paired with specific automated protocols to concentrate, extract, and purifying pathogenic or human genetic material. Their flow-through nature allows large quantities sample to be processed. Matrices may be filtered using size exclusion and/or affinity filters to concentrate the pathogen of interest. Lysed material is ultimately passed through a filter to remove the insoluble material before the soluble genetic material is delivered past a silica-like membrane that binds the genetic material, where it is washed, dried, and eluted. Cartridges are inserted into the housing areas of flow-through automated instruments, which are equipped with sensors to ensure proper placement and usage of the cartridges. Properly inserted cartridges create fluid- and air-tight seals with the flow lines of an automated instrument.

  7. Determination of mercurial species in fish by inductively coupled plasma mass spectrometry with anion exchange chromatographic separation.

    PubMed

    Chen, Xiaopan; Han, Chao; Cheng, Heyong; Liu, Jinhua; Xu, Zigang; Yin, Xuefeng

    2013-09-24

    This work demonstrated the feasibility of mercury speciation analysis by anion exchange chromatographic separation with inductively coupled plasma mass spectrometry detection. For the first time, by complexing with the mobile phase containing 3-mercapto-1-propanesulfonate into negatively charged complexes, fast separation of inorganic mercury (Hg(2+)), monomethylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg) was achieved within 5 min on a 12.5-mm strong anion exchange column. The detection limits for Hg(2+), MeHg, EtHg and PhHg were 0.008, 0.024, 0.029 and 0.034 μg L(-1), respectively. The relative standard deviations of peak height and peak area (5.0 μg L(-1) for each Hg species) were all below 3%. The determined contents of Hg(2+), MeHg and total Hg in a certified reference material of fish tissue by the proposed method were in good accordance with the certified values with satisfactory recoveries. The relative errors for determining MeHg and total mercury were -2.4% and -1.2%, respectively, with an acceptable range for spike recoveries of 94-101%. Mercury speciation in 11 fish samples were then analyzed after the pretreated procedure. The mercury contents in all fish samples analyzed were found compliant with the criteria of the National Standards of China.

  8. Degradation of imidazolium- and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone) anion exchange membranes.

    PubMed

    Chen, Dongyang; Hickner, Michael A

    2012-11-01

    Imidazolium and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone)s were synthesized successfully with the same degree of cationic functionalization and identical polymer backbones for a comparative study of anion exchange membranes (AEMs) for solid-state alkaline membrane fuel cells (AMFCs). Both anion exchange membranes were synthesized using a new methyl-containing monomer that avoided the use of toxic chloromethylation reagents. The polymer chemical structures were confirmed by ¹H NMR and FTIR. The derived AEMs were fully characterized by water uptake, anion conductivity, stability under aqueous basic conditions, and thermal stability. Interestingly, both the cationic groups and the polymer backbone were found to be degraded in 1 M NaOH solution at 60 °C over 48 h as measured by changes of ion exchange capacity and intrinsic viscosity. Imidazolium-functionalized poly(fluorenyl ether ketone sulfone)s had similar aqueous alkaline stability to quaternary ammonium-functionalized materials at 60 °C but much lower stability at 80 °C. This work demonstrates that quaternary ammonium and imidazolium cationic groups are not stable on poly(arylene ether sulfone) backbones under relatively mild conditions. Additionally, the poly(arylene ether sulfone) backbone, which is one of the most common polymers used in ion exchange membrane applications, is not stable in the types of molecular configurations analyzed.

  9. Effects of substituents and substitution positions on alkaline stability of imidazolium cations and their corresponding anion-exchange membranes.

    PubMed

    Si, Zhihong; Qiu, Lihua; Dong, Huilong; Gu, Fenglou; Li, Youyong; Yan, Feng

    2014-03-26

    Imidazolium cations with butyl groups at various substitution positions (N1-, C2-, and N3-), 1-butyl-2,3-dimethylimidazolium ([N1-BDMIm](+)), 2-butyl-1,3-dimethylimidazolium ([C2-BDMIm](+)), and 3-butyl-1,2-dimethylimidazolium ([N3-BDMIm](+)), were synthesized. Quantitative (1)H NMR spectra and density functional theory calculation were applied to investigate the chemical stability of the imidazolium cations in alkaline solutions. The results suggested that the alkaline stability of the imidazolium cations was drastically affected by the C2-substitution groups. The alkaline stability of imidazolium cations with various substitution groups at the C2-position, including 2-ethyl-1-butyl-3-methylimidazolium ([C2-EBMIm](+)), 1,2-dibutyl-3-methylimidazolium ([C2-BBMIm](+)), and 2-hydroxymethyl-1-butyl-3-methylimidazolium ([C2-HMBMIm](+)), was further studied. The butyl group substituted imidazolium cation ([C2-BBMIm](+)) exhibited the highest alkaline stability at the elevated temperatures. The synthesized anion-exchange membranes based on the [C2-BBMIm](+) cation showed promising alkaline stability. These observations should pave the way to the practical application of imidazolium-based anion exchange membrane fuel cells.

  10. Degradation of Imidazolium- and Quaternary Ammonium-Functionalized Poly(fluorenyl ether ketone sulfone) Anion Exchange Membranes

    SciTech Connect

    Chen, DY; Hickner, MA

    2012-11-01

    Imidazolium and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone)s were synthesized successfully with the same degree of cationic functionalization and identical polymer backbones for a comparative study of anion exchange membranes (AEMs) for solid-state alkaline membrane fuel cells (AMFCs). Both anion exchange membranes were synthesized using a new methyl-containing monomer that avoided the use of toxic chloromethylation reagents. The polymer chemical structures were confirmed by H-1 NMR and FTIR. The derived AEMs were fully characterized by water uptake, anion conductivity, stability under aqueous basic conditions, and thermal stability. Interestingly, both the cationic groups and the polymer backbone were found to be degraded in 1 M NaOH solution at 60 degrees C over 48 h as measured by changes of ion exchange capacity and intrinsic viscosity. Imidazolium-functionalized poly(fluorenyl ether ketone sulfone)s had similar aqueous alkaline stability to quaternary ammonium-functionalized materials at 60 degrees C but much lower stability at 80 degrees C. This work demonstrates that quaternary ammonium and imidazolium cationic groups are not stable on poly(arylene ether sulfone) backbones under relatively mild conditions. Additionally, the poly(arylene ether sulfone) backbone, which is one of the most common polymers used in ion exchange membrane applications, is not stable in the types of molecular configurations analyzed.

  11. Feasibility and kinetics study on the direct bio-regeneration of perchlorate laden anion-exchange resin.

    PubMed

    Wang, Chao; Lippincott, Lee; Meng, Xiaoguang

    2008-11-01

    Anion exchange is one of the most promising treatment technologies for the removal of low levels of perchlorate. The spent anion-exchange resins, however, need to be disposed of or regenerated because they contain high contents of perchlorate. This study investigated the feasibility and kinetics of a direct bio-regeneration method. The method accomplished resin regeneration and biological perchlorate destruction concurrently, by directly contacting the spent resin with the perchlorate-reducing bacteria (PRB). The results indicated that the method was effective in regeneration of perchlorate and nitrate loaded resin and the resin could be repeatedly regenerated with the method. The regenerated resin was effective, stable, and durable in the filtration treatment of perchlorate in well water from the Saddle River area, NJ. Moreover, the method was also effective in regeneration of the spent A-530E resin, which had high perchlorate affinity and was yet very difficult for regeneration with the conventional brine desorption technique. Besides, the results further suggested that the perchlorate and nitrate desorption from the loaded resin coupling with their subsequent biological reduction could be the direct bio-regeneration mechanism. No biofilm was formed on the regenerated resin surface according to a scanning electron microscopy (SEM) analysis.

  12. Speciation of trace elements in human serum by micro anion exchange chromatography coupled with inductively coupled plasma mass spectrometry.

    PubMed

    Malavolta, Marco; Piacenza, Francesco; Basso, Andrea; Giacconi, Robertina; Costarelli, Laura; Pierpaoli, Sara; Mocchegiani, Eugenio

    2012-02-01

    Speciation analysis of essential trace elements in human serum provides important information on nutritional status and homeostatic mechanisms regulating transport processes, acute phase reactions, and protection against oxidative damage. Anion exchange high-performance liquid chromatography (HPLC) combined with inductively coupled plasma mass spectrometry (ICP-MS) has proved to be a useful tool in speciation. Here we describe a fast method that can be applied to carry out the speciation of Fe, Cu, Zn, and Se in as little as 1 microl [corrected] of serum. The method employs monolithic anion exchange micro columns installed on a tandem HPLC system coupled on-line with an ICP-MS detector. The chromatographic separation is similar to those reported previously but with considerable gain in terms of time and sample requirement. Reproducibility is acceptable for most species. Using our method, we were able to find species-specific differences between different commercially available trace element reference materials. Because the method chosen to collect blood might interfere with speciation, the proposed methodology was used to compare heparinized plasma, ethylenediaminetetraacetic acid (EDTA) plasma, and serum from adult healthy volunteers. As expected, EDTA strongly affects speciation analysis (especially for Fe and Zn), whereas changes due to the use of lithium-heparin (Li-He) as anticoagulant appear to be minimized.

  13. Boric acid increases the expression levels of human anion exchanger genes SLC4A2 and SLC4A3.

    PubMed

    Akbas, F; Aydin, Z

    2012-04-03

    Boron is an important micronutrient in plants and animals. The role of boron in living systems includes coordinated regulation of gene expression, growth and proliferation of higher plants and animals. There are several well-defined genes associated with boron transportation and tolerance in plants and these genes show close homology with human anion exchanger genes. Mutation of these genes also characterizes some genetic disorders. We investigated the toxic effects of boric acid on HEK293 cells and mRNA expression of anion exchanger (SLC4A1, SLC4A2 and SLC4A3) genes. Cytotoxicity of boric acid at different concentrations was tested by using the methylthiazolyldiphenyl-tetrazolium bromide assay. Gene expression profiles were examined using quantitative real-time PCR. In the HEK293 cells, the nontoxic upper concentration of boric acid was 250 μM; more than 500 μM caused cytotoxicity. The 250 μM boric acid concentration increased gene expression level of SLC4A2 up to 8.6-fold and SLC4A3 up to 2.6-fold, after 36-h incubation. There was no significant effect of boric acid on SLC4A1 mRNA expression levels.

  14. Investigation of Anion-Exchange and Immunoaffinity Particle-Loaded Membranes for the Isolation of Charged Organic Analytes from Water

    USGS Publications Warehouse

    Dombrowski, T.R.; Wilson, G.S.; Thurman, E.M.

    1998-01-01

    Anion-exchange and immunoaffinity particle loaded membranes (PLMs) were investigated as a mechanism for the isolation of charged organic analytes from water. Kinetic properties determined theoretically included dynamic capacity, pressure drop (??P), residence and diffusion times (Tr, Td), and total membrane porosity (???T). These properties were confirmed through experimental evaluation, and the PLM method showed significant improvement over conventional solid-phase extraction (SPE) and ion-exchange formats. Recoveries of more than 90% were observed for a variety of test compounds at flow rates up to 70 mL/min (equipment-limited maximum flow rate). A fast-flow immunoaffinity column was developed using antibodies (Abs) attached to the PLMs. Reproducible recoveries (88% ?? 4%) were observed at flow rates up to 70 mL/min for the antibody (Ab)-loaded PLMs. Findings indicate increased selectivity over anion-exchange PLMs and conventional SPE or ion-exchange methods and rapid Ab-antigen binding rates given the excellent mass-transfer characteristics of the PLMs.

  15. Adsorptive removal of emerging polyfluoroalky substances F-53B and PFOS by anion-exchange resin: A comparative study.

    PubMed

    Gao, Yanxin; Deng, Shubo; Du, Ziwen; Liu, Kai; Yu, Gang

    2017-02-05

    Chrome plating is an important emission source of perfluorinated compounds (PFCs) industrial uses in China, where two commercial products potassium 2-(6-chloro-1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyloxy) (F-53B) and perfluorooctane sulfonate (PFOS) are applied as mist suppressant, causing non-negligible environmental risk. In this paper, anion-exchange resin IRA67 was evaluated for F-53B and PFOS removal from simulated and actual wastewater. Adsorption kinetics exhibited higher adsorption velocity and capacity of IRA67 for PFOS than F-53B due to their difference in molecular structures. Adsorption isotherms demonstrated the adsorption capacity of F-53B and PFOS on IRA67 was 4.2mmol/g and 5.5mmol/g, respectively. Because of the deprotonating of amine groups, solution pH had significant effect on IRA67 at pH>10. The results indicated that besides anion exchange other interactions including hydrophobic interaction and the formation of micelles or hemi-micelles were all involved in adsorption process. Coexisting sulfate and chromate in wastewater decreased adsorption capacities of F-53B and PFOS. The spent resin could be regenerated by the NaCl/NaOH and methanol mixed solution. In the mixed system and actual wastewater IRA67 can simultaneously remove F-53B and PFOS without obvious preference but the removal percent can be affected by competitive effect.

  16. Determination of light rare earth elements in apatite by x-ray fluorescence spectrometry after anion exchange extraction

    SciTech Connect

    Roelandts, I.

    1981-04-01

    The results of an investigation, the purpose of which was to study the feasibility of analysis of La, Ce, Pr, and Nd in apatite minerals, utilizing x-ray fluorescence spectrometry (XRF), are discussed. After sample dissolution in HNO/sub 3/, rare-earth elements (REEs) are separated by a mixed solvent anion exchange using the batch extraction technique. The anion exchanger employed is the strongly basic resin Dowex 1X8, 100 to 200 mesh (nitrate form). REEs are fixed on the resin from a medium consisting of 95% CH/sub 3/OH-5% 7 M HNO/sub 3/ (v/v). The dried resin is uniformly spread over a disk of self-adhesive foil backed with a cellulose support. The thin resin film formed is then used for XRF analysis. Synthetic standards prepared following the same procedure are employed for calibration. Analytical results of two apatite samples are presented. Good correlation is obtained between XRF and neutron activation analysis data. Limits of detection, precision, and accuracy of the results are discussed.

  17. Preparation of a weak anion exchange/hydrophobic interaction dual-function mixed-mode chromatography stationary phase for protein separation using click chemistry.

    PubMed

    Zhao, Kailou; Yang, Fan; Xia, Hongjun; Wang, Fei; Song, Qingguo; Bai, Quan

    2015-03-01

    In this study, 3-diethylamino-1-propyne was covalently bonded to the azide-silica by a click reaction to obtain a novel dual-function mixed-mode chromatography stationary phase for protein separation with a ligand containing tertiary amine and two ethyl groups capable of electrostatic and hydrophobic interaction functionalities, which can display hydrophobic interaction chromatography character in a high-salt-concentration mobile phase and weak anion exchange character in a low-salt-concentration mobile phase employed for protein separation. As a result, it can be employed to separate proteins with weak anion exchange and hydrophobic interaction modes, respectively. The resolution and selectivity of the stationary phase were evaluated in both hydrophobic interaction and ion exchange modes with standard proteins, respectively, which can be comparable to that of conventional weak anion exchange and hydrophobic interaction chromatography columns. Therefore, the synthesized weak anion exchange/hydrophobic interaction dual-function mixed-mode chromatography column can be used to replace two corresponding conventional weak anion exchange and hydrophobic interaction chromatography columns to separate proteins. Based on this mixed-mode chromatography stationary phase, a new off-line two-dimensional liquid chromatography technology using only a single dual-function mixed-mode chromatography column was developed. Nine kinds of tested proteins can be separated completely using the developed method within 2.0 h.

  18. Chromatographic evaluation of reversed-phase/anion-exchange/cation-exchange trimodal stationary phases prepared by electrostatically driven self-assembly process.

    PubMed

    Liu, Xiaodong; Pohl, Christopher; Woodruff, Andrew; Chen, Jinhua

    2011-06-03

    This work describes chromatographic properties of reversed-phase/cation-exchange/anion-exchange trimodal stationary phases. These stationary phases were based on high-purity porous spherical silica particles coated with nano-polymer beads using an electrostatically driven self-assembly process. The inner-pore area of the material was modified covalently with an organic layer that provided both reversed-phase and anion-exchange properties while the outer surface was coated with nano-sized polymer beads with strong cation-exchange characteristics. This design ensured spatial separation of the anion-exchange and the cation-exchange regions, and allowed reversed-phase, anion-exchange and cation-exchange retention mechanisms to function simultaneously. Chromatographic evaluation of ions and small molecules suggested that retention of ionic analytes was influenced by the ionic strength, pH, and mobile phase organic solvent content, and governed by both ion-exchange and hydrophobic interactions. Meanwhile, neutral analytes were retained by hydrophobic interaction and was mainly affected by mobile phase organic solvent content. Depending on the specific application, selectivity could be optimized by adjusting the anion-exchange/cation-exchange capacity ratio (selectivity), which was achieved experimentally by using porous silica particles with different surface areas.

  19. Catalytic activity for decomposition of hydrogen peroxide by metal complexes of water-soluble thiacalix[4]arenetetrasulfonate on the modified anion-exchangers.

    PubMed

    Odo, Junichi; Yamaguchi, Hanae; Ohsaki, Hirotaka; Ohmura, Noriyoshi

    2004-02-01

    The catalytic activity for the decomposition of hydrogen peroxide by anion-exchangers modified with metal complexes of thiacalix[4]arenetetrasulfonate (Me(n+)-TCAS[4], Me(n+)=Mn(3+), Mn(2+), Fe(3+), Co(3+), Co(2+), Cu(2+), Zn(2+) and Ni(2+)) was investigated. As a reference, calix[4]arenetetrasulfonate, calix[6]arenehexasulfonate and calix[8]areneoctasulfonate were also examined. Mn(3+)- and Fe(3+)-TCAS[4] on the modified anion-exchangers showed high catalytic activity in alkaline buffer solutions among metal complexes tested. Mn(3+)- and Fe(3+)-TCAS[4] on the modified anion-exchangers exhibited high and constant levels of catalytic activity even after having been used 5 times, and showed catalytic activity in the presence of an excess of H(2)O(2) over Mn(3+)- and Fe(3+)-TCAS[4] on the modified anion-exchangers. Only Mn(3+)-TCAS[4] on the modified anion-exchangers exhibited high catalytic activity at around a neutral pH.

  20. On-line two-dimensional capillary strong anion exchange/reversed phase liquid chromatography-tandem mass spectrometry for comprehensive lipid analysis.

    PubMed

    Bang, Dae Young; Moon, Myeong Hee

    2013-10-04

    An on-line two-dimensional liquid chromatography method was developed for comprehensive lipid profiling by coupling strong anion exchange (SAX) and nanoflow reversed-phase liquid chromatography (nRPLC) prior to electrospray ionization-tandem mass spectrometry (2D-SAX/nRPLC-ESI-MS/MS). Lipids can be classified into four different types according to the electrical propensities of the lipids: anionic, weak anionic, neutral polar, and special lipids. In 2D-SAX/nRPLC, various lipids can be fractionated in the first dimension (SAX: 5 μm to 100 Å, 5.0 cm × 75 μm i.d.) by step elution (methanol and salt solution), followed by the molecular separation of lipids in the second dimension (RP: 3 μm to 100 Å, 7.0 cm × 75 μm i.d.) with binary gradient LC. Since the elution of lipids from SAX can be achieved with a very small volume of eluent delivered from an autosampler, it can be simply implemented with an LC-ESI-MS instrument for full automation, and the salt step elution, including the two-step injection procedure, can be used for the selective analysis of the desired lipid fraction. For nRPLC-ESI-MS/MS run in either positive or negative ion mode, a common ionization modifier (0.05% ammonium hydroxide with 5mM ammonium formate) was introduced into the binary mobile phase solutions so that 2D-LC-MS could be operated in both ion modes without changing the mobile phase solutions. The developed on-line 2D-SAX/nRPLC-ESI-MS/MS was evaluated with 22 different standard lipids for the optimization of the salt step elution and was applied to a healthy human plasma lipid extract, resulting in the identification of a total of 303 plasma lipids, including 14 different classes.

  1. Chiral anion exchangers applied to capillary electrochromatography enantioseparation of oppositely charged chiral analytes: investigation of stationary and mobile phase parameters.

    PubMed

    Lämmerhofer, M; Tobler, E; Lindner, W

    2000-07-28

    Weak anion-exchange (WAX) type chiral stationary phases (CSPs) based on tert.-butyl carbamoyl quinine as chiral selector (SO) and different types of silica particles (porous and non-porous) as chromatographic support are evaluated in packed capillary electrochromatography (CEC). Their ability to resolve the enantiomers of negatively charged chiral analytes, e.g., N-derivatized amino acids, in the anion-exchange mode and their electrochromatographic characteristics are described in dependence of several mobile phase parameters (pH, buffer type and concentration, organic modifier type and concentration) and other experimental variables (electric field strength, capillary temperature). The inherent "zwitterionic" surface character of such silica-based WAX type CSPs (positively charged SO and negatively charged residual silanols) allows the reversal of the electroosmotic flow (EOF) towards the anode at pH values below the isoelectric point (pI) of the modified surface, whereas a cathodic EOF results at pH values above the pI. Since for negatively charged analytes also an electrophoretic transport increment has to be considered, which can be either in or against the EOF direction, several distinct modes of elution have been observed under different stationary phase and mobile phase conditions: (i) co-electrophoretic elution of the negatively charged solutes with the anodic EOF in the negative polarity mode, (ii) counter-electrophoretic elution with the cathodic EOF in the positive polarity mode, and (iii) electrophoretically dominated elution in the negative polarity mode with a cathodic EOF directed to the injection end of the capillary. Useful enantioseparations of chiral acids have been obtained with all three modes. Enantioselectivity values as high as under pressure-driven conditions and theoretical plate numbers up to 120000 per meter could be achieved under electrically driven conditions. A repeatability study yielded RSD values below 2% for retention times and

  2. Separation of Uncharged Oligodeoxynucleotide Analogs by Anion-Exchange Chromatography at High pH

    NASA Technical Reports Server (NTRS)

    Schmidt, Jurgen G.; Nielsen, Peter E.; Orgel, Leslie

    1996-01-01

    Ion-exchange chromatography is a well-established method for the analysis and purification of phosphodiester-linked oligonucleotides. If elution is carried out under alkaline conditions, the secondary structure of G- and C-rich oligomers is disrupted. Furthermore, elution times become more sensitive to the G and T content of the oligomer, because G and T are deprotonated at pH 10. In recent work on peptide-nucleic acids (PNAs) we noted that mixtures of PNA oligomers G(sub 4), G(Sub 6), G(sub 8), and G(sub 10) are readily separated by elution at pH 12 on an RPC-5 column. Here we show that this separation method is more generally applicable.

  3. Separation of 'Uncharged' Oligodeoxynucleotide Analogs by Anion-Exchange Chromatography at High pH

    NASA Technical Reports Server (NTRS)

    Schmidt, Jurgen G.; Orgel, Leslie E.; Nielsen, Peter E.

    1996-01-01

    Ion-exchange chromatography is a well-established method for the analysis and purification of phosphodiester-linked oligonucleotides. If elution is carried out under alkaline conditions, the secondary structure of G- and C-rich oligomers is disrupted. Furthermore, elution times become more sensitive to the G and T content of the oligomer, because G and T are deprotonated at pH 10. In recent work on peptide-nucleic acids (PNAs) we noted that mixtures of PNA oligomers G(sub 4), G(sub 6), G(sub 8), and G9(sub 10) are readily separated by elution at pH 12 on an RPC-5 column. Here we show that this separation method is more generally applicable.

  4. Automated two-column purification of iminobiotin and BrdU-labeled PCR products for rapid cloning: application to genes synthesized by polymerase chain assembly.

    PubMed

    TerMaat, Joel R; Mamedov, Tarlan G; Pienaar, Elsje; Whitney, Scott E; Subramanian, Anuradha

    2010-02-01

    Polymerase chain assembly (PCA) is a powerful tool for basic biological research and biotechnology applications. During the last several years, major advances have been made in de novo gene synthesis. However, there is still a need for fast and reproducible methods to automatically purify the synthesized genes. Upon completion of PCA, the subsequent PCR-amplified product mixture still contains undesired shorter DNA fragments that hinder cloning efforts. To avoid tedious gel purification, an automated two-column purification has been developed and used in conjunction with rapid PCA. The system enables fast synthesis and isolation of the full-length DNA of interest, important for facile cloning of desired DNA fragments. During the PCR amplification step, forward and reverse primers tagged with iminobiotin and bromodeoxyuridine labels, respectively, were used. The automated purification was then performed on the PCR mixture using two affinity/immunocapture columns in series to isolate only the desired full-length product. The procedure has been applied to the pUC19 beta-lactamase gene (929 bp). Follow-up PCR of the purified product, cloning, and sequencing demonstrated the technique's effectiveness in obtaining the pure full-length gene. The purification has also been performed on other synthesized genes, indicating its utility as a general approach.

  5. Novel simple process for tocopherols selective recovery from vegetable oils by adsorption and desorption with an anion-exchange resin.

    PubMed

    Hiromori, Kousuke; Shibasaki-Kitakawa, Naomi; Nakashima, Kazunori; Yonemoto, Toshikuni

    2016-03-01

    A novel and simple low-temperature process was used to recover tocopherols from a deodorizer distillate, which is a by-product of edible oil refining. The process consists of three operations: the esterification of free fatty acids with a cation-exchange resin catalyst, the adsorption of tocopherols onto an anion-exchange resin, and tocopherol desorption from the resin. No degradation of tocopherols occurred during these processes. In the tocopherol-rich fraction, no impurities such as sterols or glycerides were present. These impurities are commonly found in the product of the conventional process. This novel process improves the overall recovery ratio and the mass fraction of the product (75.9% and 51.0wt%) compared with those in the conventional process (50% and 35wt%).

  6. Highly sensitive determination of ectoine and other compatible solutes by anion-exchange chromatography and pulsed amperometric detection.

    PubMed

    Riis, Volker; Maskow, Thomas; Babel, Wolfgang

    2003-09-01

    In saline media prokaryotes compensate for the osmotic pressure of the surrounding medium by producing osmolytes. Although these osmolytes or osmoprotectors have quite diverse structures, most of them can be determined by anion-exchange chromatography combined with integrated pulsed amperometric detection. This technique offers the advantages of very high sensitivity and new opportunities to determine ectoine and 5-hydroxyectoine-two important osmolytes -after hydrolytic cleavage of the pyrimidine ring. It can even be used to screen bacterial colonies on agar for compatible solutes. Furthermore, it allows amino acids and osmolytes of this type to be determined without derivatization. To test the method we applied it to two halotolerant bacterial strains: Stenotrophomonas rhizophila DSM 14405(T) and Halomonas elongata DSM 2581(T). The first strain produced trehalose and glucosylglycerol, and the second ectoine, as the main osmotic counterweight. The relationship between the content of these osmolytes in the bacterial biomass and the external salinity is described.

  7. Chiral separation of 2-hydroxyglutaric acid on cinchonan carbamate based weak chiral anion exchangers by high-performance liquid chromatography.

    PubMed

    Calderón, Carlos; Horak, Jeannie; Lämmerhofer, Michael

    2016-10-07

    d- and l-2-Hydroxyglutaric acid (d- and l-2-HG, respectively) are metabolites related to some diseases (2-hydroxyglutaric aciduria, cancer), which make their identification and analysis crucially important for diagnostic purposes. Chiral stationary phases (CSP) based on tert-butylcarbamoyl-quinine and -quinidine (Chiralpak QN-AX and QD-AX), and the corresponding zwitterionic derivatives (Chiralpak ZWIX(+) and Chiralpak ZWIX(-)) were employed in a weak anion-exchange mechanism to perform the enantiomer separation of d- and l-2-HG without derivatization. QD-AX CSP showed the most promising separation and therefore optimization of eluent, additives, and temperature, required for the baseline separation of solutes was carried out. Depending on experimental conditions resolution values ranged up to 2.0 with run times <20min and MS-compatible conditions. Inversion on the elution order of d- and l-2-HG was possible by using the pseudo-enantiomeric QN-AX CSP.

  8. Selenium speciation by high-performance anion-exchange chromatography-post-column UV irradiation coupled with atomic fluorescence spectrometry.

    PubMed

    Liang, Lina; Mo, Shumin; Zhang, Ping; Cai, Yaqi; Mou, Shifen; Jiang, Guibin; Wen, Meijuan

    2006-06-16

    A technique for the speciation of selenomethylcysteine (SeMeCys), selenocystine (SeCys), selenite [Se(IV)] and selenomethionine (SeMet) was established in this paper using high-performance anion-exchange chromatography coupled with atomic fluorescence spectrometry (HPAEC-AFS). Analytes were separated on an AminoPac PA10 column and then digested by on-line ultraviolet (UV) irradiation, which destroyed organic compound structure. Hydride generation was used as an available sample introduction technique for atomic fluorescence detection. The detection limits of four compounds were 1-5 microg/L (250 microL injection, 10 times of the baseline noise). The relative standard deviations (RSDs), calculated from seven consecutive injections of 100 microg/L standard mixtures, were from 2 to 4%. Selenious yeast tablet, which had been proposed as selenium supplement, and human urine collected from a volunteer were analyzed. Good spiked recoveries from 86 to 103% were obtained.

  9. The comparative effects of gamma radiation and in situ alpha particles on five strong-base anion exchange resins

    SciTech Connect

    Marsh, S.F.

    1991-01-01

    The effects of external gamma radiation and in situ alpha particles were measured on a recently available, macroporous, strong-base polyvinylpyridine resin and on four strong-base polystyrene anion exchange resins. Each resin was irradiated in 7 M nitric acid to 1--10 megaGray of gamma radiation from external {sup 60}Co, or to 5--14 megaGray of alpha particles from sorbed {sup 238}Pu. Each irradiated resin was measured for changes in dry weight, wet volume, weak-base and strong-base chloride exchange capacities, and exchange capacities for Pu(4) from nitric acid. Alpha-induced resin damage was significantly less than that caused by an equivalent dose of gamma radiation. The polyvinylpyridine resin offers the greatest resistance to damage from gamma radiation and from alpha particles. 5 refs., 1 figs. 5 tabs.

  10. Stable and selective scintillating anion-exchange sensors for quantification of 99TcO4- in natural freshwaters.

    PubMed

    Seliman, Ayman F; Helariutta, Kerttuli; Wiktorowicz, Szymon J; Tenhu, Heikki; Harjula, Risto

    2013-12-01

    New dual functionality scintillating anion-exchange resins were developed for selective determination of (99)TcO4(-) in various natural freshwater samples. Stable scintillating particles were formed by preparing the vinyl monomer 2-[4-(4'-vinylbiphenylyl)]-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (vPBD), starting with the commercial organic flour TBut-PBD and its subsequent copolymerization with styrene, divinylbenzene, and p-chloromethylstyrene mixture. To integrate the radiochemical separation and radiometric detection steps within the same bead, the chloromethyl groups of the scintillating resins were subjected to amination reactions with dioctylamine (DOA) and trioctylamine (TOA). On-line quantification of (99)TcO4(-) was achieved by packing the scintillating anion-exchange resin into Teflon tubing for quantification by a flow scintillation analyzer (FSA). The two functionalized resins were selective for pertechnetate over the common anions in natural freshwaters, especially Cl(-) and SO4(2-) with up to 1000 ppm and with up to 10 ppm I(-) and Cr2O7(2-). The uptake efficiency of the TOA sensor decreased from 97.88% to 85.08% in well water and river water, respectively, while the counting efficiency was almost constant (69.50%). The DOA performance showed lower efficiency in the two water types relative to TOA. On the other hand, the DOA sensor could be regenerated by 5 M HNO3 for reuse at least four times without losing its chemical or optical performance. The detection limit was 1.45 Bq which could be achieved by loading 45 mL from well and tap water containing the maximum contaminant level (MCL) of (99)Tc (33 Bq/L).

  11. Potential of chiral anion-exchangers operated in various subcritical fluid chromatography modes for resolution of chiral acids.

    PubMed

    Pell, Reinhard; Lindner, Wolfgang

    2012-07-06

    Anion-exchange-type chiral stationary phases (CSPs) derived from quinine or quinidine were applied in subcritical fluid chromatography (SFC) for the direct separation of chiral acidic compounds. Employing subcritical (sc) mobile phase modes (CO₂ + methanol as co-solvent and acids and bases as additives) first the influence of type and amount of acidic and basic additives on separation performance was investigated. Secondly, water was tested as a neutral additive and the influence of temperature variation on enantioselectivity was studied. Thirdly, we could chromatographically confirm that the often verbalized "inherent acidity" of sc CO₂ + methanol is manifested by the in situ formation of methylcarbonic acids in the sc mobile phase and thus functioning as acidic additive. Accordingly the dissociated methylcarbonic acid, acting as a counterion, enables an anion exchange mechanism between the cationic CSP and the corresponding acidic analyte. In the absence of a dissociable acid in the mobile phase such an ion exchange mode would not work following a stoichiometric displacement model. This finding is further corroborated by the use of ammonia in methanol as co-solvent thus generating in situ the ammonium salt of methylcarbonic acid. In summary, we report on ion-exchange mediated chromatographic separations in SFC modes by merely using (i) sc CO₂ and MeOH, (ii) sc CO₂ and ammonia in MeOH, and (iii) sc CO₂ and MeOH plus acids and bases as additives. Comparisons to HPLC mode have been undertaken to evaluate merits and limitations. This mode exhibits high potential for preparative chromatography of chiral acids combining pronounced enantioselectivity with high column loadability and avoiding possibly troublesome mobile phase additives, as the in situ formed methylcarbonic acid disintegrates to CO₂ and methanol upon pressure release.

  12. Human kidney anion exchanger 1 interacts with adaptor-related protein complex 1 {mu}1A (AP-1 mu1A)

    SciTech Connect

    Sawasdee, Nunghathai; Junking, Mutita; Ngaojanlar, Piengpaga; Sukomon, Nattakan; Ungsupravate, Duangporn; Limjindaporn, Thawornchai; Akkarapatumwong, Varaporn; Noisakran, Sansanee; Yenchitsomanus, Pa-thai

    2010-10-08

    Research highlights: {yields} Trafficking defect of kAE1 is a cause of dRTA but trafficking pathway of kAE1 has not been clearly described. {yields} Adaptor-related protein complex 1 {mu}1A (AP-1 mu1A) was firstly reported to interact with kAE1. {yields} The interacting site for AP-1 mu1A on Ct-kAE1 was found to be Y904DEV907, a subset of YXXO motif. {yields} AP-1 mu1A knockdown showed a marked reduction of kAE1 on the cell membrane and its accumulation in endoplasmic reticulum. {yields} AP-1 mu1A has a critical role in kAE1 trafficking to the plasma membrane. -- Abstract: Kidney anion exchanger 1 (kAE1) mediates chloride (Cl{sup -}) and bicarbonate (HCO{sub 3}{sup -}) exchange at the basolateral membrane of kidney {alpha}-intercalated cells. Impaired trafficking of kAE1 leads to defect of the Cl{sup -}/HCO{sub 3}{sup -} exchange at the basolateral membrane and failure of proton (H{sup +}) secretion at the apical membrane, causing a kidney disease - distal renal tubular acidosis (dRTA). To gain a better insight into kAE1 trafficking, we searched for proteins physically interacting with the C-terminal region of kAE1 (Ct-kAE1), which contains motifs crucial for intracellular trafficking, by a yeast two-hybrid (Y2H) system. An adaptor-related protein complex 1 {mu}1A (AP-1 mu1A) subunit was found to interact with Ct-kAE1. The interaction between either Ct-kAE1 or full-length kAE1 and AP-1 mu1A were confirmed in human embryonic kidney (HEK) 293T by co-immunoprecipitation, affinity co-purification, co-localization, yellow fluorescent protein (YFP)-based protein fragment complementation assay (PCA) and GST pull-down assay. The interacting site for AP-1 mu1A on Ct-kAE1 was found to be Y904DEV907, a subset of YXXO motif. Interestingly, suppression of endogenous AP-1 mu1A in HEK 293T by small interfering RNA (siRNA) decreased membrane localization of kAE1 and increased its intracellular accumulation, suggesting for the first time that AP-1 mu1A is involved in the kAE1

  13. Selectivity control in synergistic liquid-liquid anion exchange of univalent anions via structure-specific cooperativity between quaternary ammonium cations and anion receptors.

    PubMed

    Borman, Christopher J; Bonnesen, Peter V; Moyer, Bruce A

    2012-10-02

    Two anion receptors enhance liquid-liquid anion exchange when added to quaternary alkylammonium chloride anion exchangers, but with a striking dependence on the structure of the alkylammonium cation that suggests a supramolecular cooperative effect. Two anion receptors were investigated, meso-octamethylcalix[4]pyrrole (C4P) and the bisthiourea tweezer 1,1'-(propane-1,3-diyl)bis(3-(4-sec-butylphenyl)thiourea (BTU). Whereas synergism is comparatively weak when either methyltri(C(8,10))alkylammonium chloride (Aliquat 336) or tetraheptylammonium chloride is used with the BTU receptor, synergism between C4P and Aliquat 336 is so pronounced that anion exchange prefers chloride over more extractable nitrate and trifluoroacetate, effectively overcoming the ubiquitous Hofmeister bias. A thermochemical analysis of synergistic anion exchange has been provided for the first time, resulting in the estimation of binding constants for C4P with the ion pairs of A336(+) with Cl(-), Br(-), OAc(F3)(-), NO(3)(-), and I(-).

  14. Comparison of reversed-phase/cation-exchange/anion-exchange trimodal stationary phases and their use in active pharmaceutical ingredient and counterion determinations.

    PubMed

    Liu, Xiaodong; Pohl, Christopher A

    2012-04-06

    This study involved three commercial reversed-phase (RP)/anion-exchange (AEX)/cation-exchange (CEX) trimodal columns, namely Acclaim Trinity P1 (Thermo Fisher Scientific), Obelisc R (SIELC Technologies) and Scherzo SM-C18 (Imtakt). Their chromatographic properties were compared in details with respect to hydrophobicity, anion-exchange capacity, cation-exchange capacity, and selectivity, by studying retention behavior dependency on organic solvent, buffer concentration and pH. It was found that their remarkably different column chemistries resulted in distinctive chromatography properties. Trinity P1 exhibited strong anion-exchange and cation-exchange interactions but low RP retention while Scherzo SM-C18 showed strong reversed-phase retention with little cation-exchange and anion-exchange capacities. For Obelisc R, its reversed-phase capacity was weaker than Scherzo SM-C18 but slightly higher than Trinity P1, and its ion-exchange retentions were between Trinity P1 and Scherzo SM-C18. In addition, their difference in selectivity was demonstrated by examples of determining the active pharmaceutical ingredient (API) and counterion of drug products.

  15. Application of cellulose anion-exchangers to separation of palladium from platinum or iridium with glycine as complexing agent and atomic-absorption spectrometry for detection.

    PubMed

    Brajter, K; Słonawska, K

    1983-07-01

    The use of glycine as complexing agent for chromatographie separation of palladium from platinum, or palladium from iridium, on cellulose anion-exchangers has been investigated and found possible over a wide range of concentration ratios. The method can be used for analysis of Pd-Ir alloys. The nature of the complexes taking part in the ion-exchange has been identified.

  16. Preparation of high-capacity, weak anion-exchange membranes by surface-initiated atom transfer radical polymerization of poly(glycidyl methacrylate) and subsequent derivatization with diethylamine

    NASA Astrophysics Data System (ADS)

    Qian, Xiaolei; Fan, Hua; Wang, Chaozhan; Wei, Yinmao

    2013-04-01

    Ion-exchange membrane is of importance for the development of membrane chromatography. In this work, a high-capacity anion-exchange membrane was prepared by grafting of glycidyl methacrylate (GMA) onto the surface of regenerated cellulose (RC) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequent derivatization with diethylamine. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to characterize changes in the chemical functionality, surface topography and pore morphology of the modified membranes. The static capacity of the prepared anion-exchange membrane was evaluated with bovine serum albumin (BSA) as a model protein. The results indicated that the anion-exchange membrane which could reach a maximum capacity of 96 mg/mL for static adsorption possesses a higher adsorption capacity, and the adsorption capacity increases with the polymerization time. The effect of pH and salt concentration confirmed that the adsorption of BSA followed ion-exchange mechanism. The established method would have potential application in the preparation of anion-exchange membrane.

  17. A new anion-exchange/hydrophobic monolith as stationary phase for nano liquid chromatography of small organic molecules and inorganic anions.

    PubMed

    Aydoğan, Cemil

    2015-05-01

    In this study, an anion-exchange/hydrophobic polymethacrylate-based stationary phase was prepared for nano-liquid chromatography of small organic molecules and inorganic anions. The stationary phase was synthesized by in situ polymerization of 3-chloro-2-hydroxypropylmethacrylate and ethylene dimethacrylate inside silanized 100 μm i.d. fused silica capillary. The porogen mixture consisted of toluene and dodecanol. The pore size distrubution profiles of the resulting monolith were determined by mercury intrusion porosimetry and the morphology of the prepared monolith was investigated by scanning electron microscope. Good permeability, stability and column efficiency were observed on the monolithic column with nano flow. The produced monolithic column, which contains reactive chloro groups, was then modified by reaction with N,N-dimethyl-N-dodecylamine to obtain an anion-exchange/hydrophobic monolithic stationary phase. The functionalized monolith contained ionizable amine groups and hydrophobic groups that are useful of anion-exchange/hydrophobic mixed-mode chromatography. The final monolithic column performance with respect to anion-exchange and hydrophobic interactions was assesed by the separation of alkylbenzene derivatives, phenolic compounds and inorganic anions, respectively. Theoretical plate numbers up to 23,000 plates/m were successfully achieved in the separation of inorganic anions.

  18. A general halide-to-anion switch for imidazolium-based ionic liquids and oligocationic systems using anion exchange resins (A- form).

    PubMed

    Alcalde, Ermitas; Dinarès, Immaculada; Ibáñez, Anna; Mesquida, Neus

    2011-03-21

    Further studies on the application of an AER (A(-) form) method broadened the anion exchange scope of representative ionic liquids and bis(imidazolium) systems. Depending on the hydrophobicity nature of the targeted imidazolium species and counteranions, different organic solvents were used to swap halides for assorted anions, proceeding in excellent to quantitative yields.

  19. Facile modification of multi-walled carbon nanotubes-polymeric ionic liquids-coated solid-phase microextraction fibers by on-fiber anion exchange.

    PubMed

    Feng, Juanjuan; Sun, Min; Bu, Yanan; Luo, Chuannan

    2015-05-08

    In situ anion exchange has been proved to be an efficient method for facile modification of polymeric ionic liquids (PILs)-based stationary phases. In this work, an on-fiber anion exchange process was utilized to tune the extraction performance of a multi-walled carbon nanotubes (MWCNTs)-poly(1-vinyl-3-octylimidazolium bromide) (poly(VOIm(+)Br(-)))-coated solid-phase microextraction (SPME) fiber. MWCNTs were first coated onto the stainless steel wire through a layer-by-layer fabrication method and then the PILs were coated onto the MWCNTs physically. Anion of the MWCNTs-poly(VOIm(+)Br(-)) fiber was changed into bis(triflroromethanesulfonyl)imide (NTf2(-)) and 2-naphthalene-sulfonate (NapSO3(-)) by on-fiber anion exchange. Coupled to gas chromatography, the MWCNTs-poly(VOIm(+)Br(-)) fiber showed acceptable extraction efficiency for hydrophilic and hydrogen-bonding-donating alcohols, with limits of detection (LODs) in the range of 0.005-0.05μgmL(-1); after the anion exchange with NTf2(-), the obtained MWCNTs-poly(VOIm(+)NTf2(-)) fiber brought wide linear ranges for hydrophobic n-alkanes with correlation coefficient (R) ranging from 0.994 to 0.997; aromatic property of the fiber was enhanced by aromatic NapSO3(-) anions to get sufficient extraction capacity for phthalate esters and halogenated aromatic hydrocarbons. The MWCNTs-poly(VOIm(+)NapSO3(-)) fiber was finally applied to determine several halogenated aromatic hydrocarbons in groundwater of industrial park.

  20. High-Throughput, Automated Protein A Purification Platform with Multiattribute LC-MS Analysis for Advanced Cell Culture Process Monitoring.

    PubMed

    Dong, Jia; Migliore, Nicole; Mehrman, Steven J; Cunningham, John; Lewis, Michael J; Hu, Ping

    2016-09-06

    The levels of many product related variants observed during the production of monoclonal antibodies are dependent on control of the manufacturing process, especially the cell culture process. However, it is difficult to characterize samples pulled from the bioreactor due to the low levels of product during the early stages of the process and the high levels of interfering reagents. Furthermore, analytical results are often not available for several days, which slows the process development cycle and prevents "real time" adjustments to the manufacturing process. To reduce the delay and enhance our ability to achieve quality targets, we have developed a low-volume, high-throughput, and high-content analytical platform for at-line product quality analysis. This workflow includes an automated, 96-well plate protein A purification step to isolate antibody product from the cell culture fermentation broth, followed by rapid, multiattribute LC-MS analysis. We have demonstrated quantitative correlations between particular process parameters with the levels of glycosylated and glycated species in a series of small scale experiments, but the platform could be used to monitor other attributes and applied across the biopharmaceutical industry.

  1. Simultaneous determination of 13 carbohydrates using high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry.

    PubMed

    Zhao, Dan; Feng, Feng; Yuan, Fei; Su, Jin; Cheng, Yan; Wu, Hanqiu; Song, Kun; Nie, Bo; Yu, Lian; Zhang, Feng

    2017-02-28

    A simple, accurate, and highly sensitive method was developed for the determination of 13 carbohydrates in polysaccharide of spirulina platensis based on high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry. Samples were extracted with deionized water using ultrasonic-assisted extraction, and the ultrasound-assisted extraction conditions were optimized by Box-Behnken design. Then the extracted polysaccharide was hydrolyzed by adding 1 mol/L trifluoroacetic acid before determination by high-performance anion-exchange chromatography coupled with pulsed amperometric detection and confirmed by high-performance anion-exchange chromatography coupled with mass spectrometry. The high-performance anion-exchange chromatography coupled with pulsed amperometric detection method was performed on a CarboPac PA20 column by gradient elution using deionized water, 0.1 mol/L sodium hydroxide solution and 0.4 mol/L sodium acetate solution. Excellent linearity was observed in the range of 0.05-10 mg/L. The average recoveries ranged from 80.7 to 121.7%. The limits of detection and limits of quantification for 13 carbohydrates were 0.02-0.10 and 0.2-1.2  μg/kg, respectively. The developed method has been successfully applied to ambient samples, and the results indicated that high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry could provide a rapid and accurate method for the simultaneous determination of carbohydrates.

  2. Microcalorimetric study of adsorption and disassembling of virus-like particles on anion exchange chromatography media.

    PubMed

    Yu, Mengran; Zhang, Songping; Zhang, Yan; Yang, Yanli; Ma, Guanghui; Su, Zhiguo

    2015-04-03

    Chromatographic purification of virus-like particles (VLPs) is important to the development of modern vaccines. However, disassembly of the VLPs on the solid-liquid interface during chromatography process could be a serious problem. In this study, isothermal titration calorimetric (ITC) measurements, together with chromatography experiments, were performed on the adsorption and disassembling of multi-subunits hepatitis B virus surface antigen virus-like particles (HB-VLPs). Two gigaporous ion-exchange chromatography (IEC) media, DEAE-AP-280 nm and DEAE-POROS, were used. The application of gigaporous media with high ligand density led to significantly increased irreversible disassembling of HB-VLPs and consequently low antigen activity recovery during IEC process. To elucidate the thermodynamic mechanism of the effect of ligand density on the adsorption and conformational change of VLPs, a thermodynamic model was proposed. With this model, one can obtain the intrinsic molar enthalpy changes related to the binding of VLPs and the accompanying conformational change on the liquid-solid interface during its adsorption. This model assumes that, when intact HB-VLPs interact with the IEC media, the total adsorbed proteins contain two states, the intact formation and the disassembled formation; accordingly, the apparent adsorption enthalpy, ΔappH, which can be directly measured from ITC experiments, presents the sum of three terms: (1) the intrinsic molar enthalpy change associated to the binding of intact HB-VLPs (ΔbindHintact), (2) the intrinsic molar enthalpy change associated to the binding of HB-VLPs disassembled formation (ΔbindHdis), and (3) the enthalpy change accompanying the disassembling of HB-VLPs (ΔconfHdis). The intrinsic binding of intact HB-VLPs and the disassembled HB-VLPs to both kinds of gigaporous media (each of which has three different ligand densities), were all observed to be entropically driven as indicated by positive values of

  3. Determination of niacin in infant formula by solid-phase extraction and anion-exchange liquid chromatography.

    PubMed

    LaCroix, D E; Wolf, W R; Porter, E; Cantellops, D; Chase, G W; Woollard, D

    2001-01-01

    A peer-verified, solid-phase extraction (SPE)/anion exchange liquid chromatographic method is presented for the determination of niacin in milk-based and soy-based infant formula. Analysis is in 3 steps: test sample digestion, extraction/cleanup, and liquid chromatography (LC). Digestion uses a standard AOAC digestion procedure that involves autoclaving at 121 degrees C for 45 min in (1 + 1) H2SO4 to free endogenous niacin from protein and to convert added niacinamide to niacin. The digest solution is adjusted to pH 6.5 with 7.5M NaOH. Acidification to pH <1.0 with (1 + 1) H2SO4 precipitates the protein. The clarified solution is then filtered, and the filtrate is brought to volume. SPE of niacin is accomplished by passing an aliquot of the digest solution through an aromatic sulfonic acid-SPE (ArSCX-SPE) column. After the column is washed with methanol and water to remove extraneous material, the niacin is eluted with 0.25M sodium acetate/acetic acid buffer at pH 5.6. An anion-exchange polystyrene-divinylbenzene column with 0.1 M sodium acetate/acetic acid buffer at pH 4.0 is used for LC. Niacin is determined by UV detection at 260 nm. A standard curve is prepared by passing known amounts of niacin through the ArSCX-SPE columns used for niacin extraction. The following values for x and relative standard deviation (RSD) were obtained for National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1846 Infant Formula with a certified value for niacin of 63.3 +/- 7.6 microg/g: Submitting laboratory.-- x = 59.7 +/- 4.0 microg/g; RSD = >6.7%; confidence interval (CI) = +/- 1.4 microg/g; n = 27. Peer laboratory.--x = 56.6 +/- 6.6 microg/g; RSD = >11.7%; CI =+/- 4.1 microg/g; n = 8.

  4. Sulfate secretion and chloride absorption are mediated by the anion exchanger DRA (Slc26a3) in the mouse cecum.

    PubMed

    Whittamore, Jonathan M; Freel, Robert W; Hatch, Marguerite

    2013-07-15

    Inorganic sulfate (SO₄²⁻) is essential for a multitude of physiological processes. The specific molecular pathway has been identified for uptake from the small intestine but is virtually unknown for the large bowel, although there is evidence for absorption involving Na⁺-independent anion exchange. A leading candidate is the apical chloride/bicarbonate (Cl⁻/HCO₃⁻) exchanger DRA (down-regulated in adenoma; Slc26a3), primarily linked to the Cl⁻ transporting defect in congenital chloride diarrhea. The present study set out to characterize transepithelial ³⁵SO₄²⁻ and ³⁶Cl⁻ fluxes across the isolated, short-circuited cecum from wild-type (WT) and knockout (KO) mice and subsequently to define the contribution of DRA. The cecum demonstrated simultaneous net SO₄²⁻ secretion (-8.39 ± 0.88 nmol·cm⁻²·h⁻¹) and Cl⁻ absorption (10.85 ± 1.41 μmol·cm⁻²·h⁻¹). In DRA-KO mice, SO₄²⁻ secretion was reversed to net absorption via a 60% reduction in serosal to mucosal SO₄²⁻ flux. Similarly, net Cl⁻ absorption was abolished and replaced by secretion, indicating that DRA represents a major pathway for transcellular SO₄²⁻ secretion and Cl⁻ absorption. Further experiments including the application of DIDS (500 μM), bumetanide (100 μM), and substitutions of extracellular Cl⁻ or HCO₃⁻/CO₂ helped to identify specific ion dependencies and driving forces and suggested that additional anion exchangers were operating at both apical and basolateral membranes supporting SO₄²⁻ transport. In conclusion, DRA contributes to SO₄²⁻ secretion via DIDS-sensitive HCO₃⁻/SO₄²⁻ exchange, in addition to being the principal DIDS-resistant Cl⁻/HCO₃⁻ exchanger. With DRA linked to the pathogenesis of other gastrointestinal diseases extending its functional characterization offers a more complete picture of its role in the intestine.

  5. The human erythrocyte anion-transport protein. Partial amino acid sequence, conformation and a possible molecular mechanism for anion exchange.

    PubMed Central

    Brock, C J; Tanner, M J; Kempf, C

    1983-01-01

    The N-terminal 72 residues of an integral membrane fragment, P5, of the human erythrocyte anion-transport protein, which is known to be directly involved in the anion-exchange process, was shown to have the following amino acid sequence: Met-Val-Pro-Lys-Pro-Gln-Gly-Pro-Leu-Pro-Asn-Thr-Ala-Leu-Leu-Ser-Leu-Val-Leu-Met -Ala-Gly-Thr-Phe-Phe-Phe-Ala-Met-Met-Leu-Arg-Lys-Phe-Lys-Asn-Ser-Ser-Tyr-Phe-Pro-Gly-Lys-Leu-Arg-Arg-Val-Ile-Gly-Asp-Phe-Gly-Val-Pro-Ile-Ser-Ile-Leu-Ile-Met-Val-Leu-Val-Asp-Phe-Phe-Ile-Gln-Asp-Thr-Tyr-Thr-Gln- The structure of this fragment was analysed, with account being taken of the constraints that apply to the folding of integral membrane proteins and the topographical locations of various sites in the sequence. It was concluded that this sequence forms two transmembrane alpha-helices. These are probably part of a cluster of amphipathic transmembrane alpha-helices, which could comprise that part of the protein responsible for transport activity. The presently available evidence relating to the anion-exchange process was considered with the structural features noted in this study and a possible molecular mechanism is proposed. In this model the rearrangement of a network of intramembranous charged pairs mediates the translocation of an anion between anion-binding regions at each surface of the membrane, which are composed of clusters of positively charged amino acids. This model imposes a sequential exchange mechanism on the system. Supplementary material, including Tables and Figures describing the compositions of peptides determined by amino acid analysis and sequence studies, quantitative and qualitative data that provide a residue-by-residue justification for the sequence assignment and a description of modifications to and use of the solid-phase sequencer has been deposited as Supplementary Publication SUP 50123 (12 pages) with the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be

  6. Effect of Fe2+ Oxidation on the Removal of 238Pu from Neptunium Solution by Anion Exchange

    SciTech Connect

    KYSER, EDWARD

    2004-06-01

    The effect of ferrous sulfamate (FS) oxidation and variation in nitric acid concentration on the removal of {sup 238}Pu contamination from Np by the HB-Line anion exchange flowsheet has been tested. Significant rejection of {sup 238}Pu was observed by washing with a reductive wash solution containing 6.0 to 6.8 M nitric acid (HNO{sub 3}) with as little as 30% of the Fe{sup 2+} from the FS remaining in its reduced form. To achieve the desired 30% removal of {sup 238}Pu from the process, conditions should be controlled to maintain the Fe{sup 2+}/Fe{sup 3+} ratio in the reductive wash to be greater than 60%/40% (or 1.5). Since Fe{sup 2+} oxidation is strongly affected by temperature and nitric acid concentration, these parameters (as well as time after FS addition) need to be controlled to ensure predictable results. A shortened-height column was utilized in these tests to match changes in the plant equipment. Lab experiments scaled to plant batch sizes of 2000 g Np were observed with modest losses for ''up-flow'' washing. The following are recommended conditions for removing {sup 238}Pu from Np solutions by anion exchange in HB-Line: (1) Feed conditions: ''Up-flow'' 6.4-8.0 M HNO{sub 3}, 0.02 M hydrazine (N{sub 2}H{sub 4}), 0.05 M excess FS. (2) Reductive Wash conditions: ''Up-flow'' 6 Bed volumes (BV) of 6.4 M HNO{sub 3}, 0.05 M FS (minimum 0.03M Fe{sup 2+} during wash cycle), 0.05 M hydrazine, less than 1.8 mL/min/cm{sup 2} flowrate. (3) Decontamination Wash conditions: ''Up-flow'' 1-2 BV of 6.4-8.0 M HNO{sub 3}, no FS, no hydrazine, less than 1.8 mL/min/cm{sup 2} flowrate. (4) Elution conditions: ''Down-flow'' 0.17 M HNO{sub 3}, 0.05 M hydrazine, no FS.

  7. Separation of oligo/polymers of 5-N-acetylneuraminic acid, 5-N-glycolylneuraminic acid, and 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid by high-performance anion-exchange chromatography with pulsed amperometric detector.

    PubMed

    Zhang, Y; Inoue, Y; Inoue, S; Lee, Y C

    1997-08-01

    A sensitive and efficient method to analyze oligo/ poly-sialic acids containing alpha2-8-linked 5-N-acetylneuraminic acid (Neu5Ac), 5-N-glycolylneuraminic acid (Neu5Gc), and deaminated neuraminic acid (KDN) using high-performance anion-exchange chromatography (HPAEC) with a pulsed amperometric detector (PAD-2) has been developed. Using a CarboPac PA-100 column and sodium nitrate as the pushing agent, polymers in colominic acid with degree of polymerization (DP) up to 80 were separated in 68 min. A similar DP-based resolution was also obtained on a CarboPac PA-1 column. The elution ladders of the Neu5Ac, Neu5Gc, and KDN series were sufficiently different to be used as diagnostic indices. This technique was applied to identification of the sialic acid components in a polysialoglycoprotein (PSGP) sample as well as monitoring the oligo/poly-KDN-containing fractions during the purification of KDN-containing glycoprotein (KDN-gp). The maximum DPs of oligo-Neu5Gc and oligo-KDN that can be detected in PSGP and KDN-gp hydrolysates were 11 and 8, respectively. The high sensitivity of this method was demonstrated by the quantification of Neu5Ac oligomers. Distributions of the monomer and oligo/polymers in the acid and enzymatic hydrolysates of colominic acid and PSGP under different conditions were also studied.

  8. Centrifugal LabTube platform for fully automated DNA purification and LAMP amplification based on an integrated, low-cost heating system.

    PubMed

    Hoehl, Melanie M; Weißert, Michael; Dannenberg, Arne; Nesch, Thomas; Paust, Nils; von Stetten, Felix; Zengerle, Roland; Slocum, Alexander H; Steigert, Juergen

    2014-06-01

    This paper introduces a disposable battery-driven heating system for loop-mediated isothermal DNA amplification (LAMP) inside a centrifugally-driven DNA purification platform (LabTube). We demonstrate LabTube-based fully automated DNA purification of as low as 100 cell-equivalents of verotoxin-producing Escherichia coli (VTEC) in water, milk and apple juice in a laboratory centrifuge, followed by integrated and automated LAMP amplification with a reduction of hands-on time from 45 to 1 min. The heating system consists of two parallel SMD thick film resistors and a NTC as heating and temperature sensing elements. They are driven by a 3 V battery and controlled by a microcontroller. The LAMP reagents are stored in the elution chamber and the amplification starts immediately after the eluate is purged into the chamber. The LabTube, including a microcontroller-based heating system, demonstrates contamination-free and automated sample-to-answer nucleic acid testing within a laboratory centrifuge. The heating system can be easily parallelized within one LabTube and it is deployable for a variety of heating and electrical applications.

  9. Intercalation chemistry in a LDH system: anion exchange process and staging phenomenon investigated by means of time-resolved, in situ X-ray diffraction.

    PubMed

    Taviot-Guého, Christine; Feng, Yongjun; Faour, Azzam; Leroux, Fabrice

    2010-07-14

    Using time-resolved, in situ energy-dispersive X-ray diffraction (EDXRD), the formation of interstratified LDH structures, with alternate interlayer spaces occupied by different anions, have been demonstrated during anion exchange reactions. Novel hybrid LDH nanostructures can thus be prepared, combining the physicochemical properties of two intercalated anions plus those of the LDH host. A general trend is that inorganic-inorganic anion exchange reactions occur in a one-step process while inorganic-organic exchanges may proceed via a second-stage intermediate, suggesting that staging occurs partly as a result of organic-inorganic separation. Yet, other influencing parameters must be considered such as LDH host composition, LDH affinity for different anions and LDH particle size as well as extrinsic parameters like the reaction temperature. Hence, a correlation between the occurrence of staging phenomenon and the difficulty of the exchange of the initial anion is observed, suggesting that staging is needed to overcome the energy barrier in the case of the exchange by organic anions. Notwithstanding the LiAl(2) system, staging has mainly been observed with Zn(2)Cr LDH host so far, a peculiar LDH composition with a unique Zn/Cr ratio of two and a local order of the cations within the hydroxide layers. The formation of a higher order-staged intermediate than stage two, observed during the exchange reaction of CO(3)(2-) or SO(4)(2-) anions with Zn(2)Cr-tartrate, is in favour of a Daumas-Herold model although this model implies a bending of LDH layers. The analysis of the X-ray powder diffraction pattern of Zn(2)Cr-Cl/tartrate second-stage intermediate, isolated almost as a pure phase during the exchange of Cl(-) with tartrate anions in Zn(2)Cr LDH, indicates a disorder in the stacking sequence and a relative proportion of the two kinds of interlayers slightly different from 50/50. Besides, the microstructural analysis of the XRD pattern reveals a great reduction of the

  10. Progress in automated extraction and purification of in situ 14C from quartz: Results from the Purdue in situ 14C laboratory

    NASA Astrophysics Data System (ADS)

    Lifton, Nathaniel; Goehring, Brent; Wilson, Jim; Kubley, Thomas; Caffee, Marc

    2015-10-01

    Current extraction methods for in situ 14C from quartz [e.g., Lifton et al., (2001), Pigati et al., (2010), Hippe et al., (2013)] are time-consuming and repetitive, making them an attractive target for automation. We report on the status of in situ 14C extraction and purification systems originally automated at the University of Arizona that have now been reconstructed and upgraded at the Purdue Rare Isotope Measurement Laboratory (PRIME Lab). The Purdue in situ 14C laboratory builds on the flow-through extraction system design of Pigati et al. (2010), automating most of the procedure by retrofitting existing valves with external servo-controlled actuators, regulating the pressure of research purity O2 inside the furnace tube via a PID-based pressure controller in concert with an inlet mass flow controller, and installing an automated liquid N2 distribution system, all driven by LabView® software. A separate system for cryogenic CO2 purification, dilution, and splitting is also fully automated, ensuring a highly repeatable process regardless of the operator. We present results from procedural blanks and an intercomparison material (CRONUS-A), as well as results of experiments to increase the amount of material used in extraction, from the standard 5 g to 10 g or above. Results thus far are quite promising with procedural blanks comparable to previous work and significant improvements in reproducibility for CRONUS-A measurements. The latter analyses also demonstrate the feasibility of quantitative extraction of in situ 14C from sample masses up to 10 g. Our lab is now analyzing unknowns routinely, but lowering overall blank levels is the focus of ongoing research.

  11. Polystyrene-divinylbenzene stationary phases agglomerated with quaternized multi-walled carbon nanotubes for anion exchange chromatography.

    PubMed

    Huang, Zhongping; Wu, Hongwei; Wang, Fengli; Yan, Wenwu; Guo, Weiqiang; Zhu, Yan

    2013-06-14

    This work explores the potential of multi-walled carbon nanotubes as an agglomerated material for ion chromatography stationary phases for the separation of inorganic anions. Polyelectrolytes with quaternary ammonium groups were introduced onto the carbon nanotube surface, based on condensation polymerization of 1,4-butanediol diglycidyl ether (BDDE) and methylamine (MA). Quaternized multi-walled carbon nanotubes (Q-MWCNTs) were electrostatically adsorbed onto the surface of sulfonated polystyrene-divinylbenzene (PS-DVB) beads to generate the anion exchanger, which were confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). A 100mm×4.0mm i.d. column was packed with Q-MWCNTs agglomerated PS-DVB particles, with a capacity of 56μequiv./column. Separation of inorganic anions, such as F(-), Cl(-), NO2(-), Br(-), NO3(-), SO4(2-) and PO4(3-) were performed. The stationary phase was rigid, chemically stable and showed good ion-exchange characteristics.

  12. Monitoring and preparation of neoagaro- and agaro-oligosaccharide products by high performance anion exchange chromatography systems.

    PubMed

    Kazłowski, Bartosz; Pan, Chorng Liang; Ko, Yuan Tih

    2015-05-20

    A series of neoagaro-oligosaccharides (NAOS) were prepared by β-agarase digestion and agaro-oligosaccharides (AOS) by HCl hydrolysis from agarose with defined quantity and degree of polymerization (DP). Chain-length distribution in the crude product mixtures were monitored by two high performance anion exchange chromatography systems coupled with a pulsed amperometric detector. Method 1 utilized two separation columns: a CarboPac(™) PA1 and a CarboPac(™) PA100 connected in series and method 2 used the PA100 alone. Method 1 resolved the product in size ranges consisting of DP 1-46 for NAOS and DP 1-32 for AOS. Method 2 clearly resolved saccharide product sizes within DP 26. The optimized system utilizing a semi-preparative CarboPac(™) PA100 column was connected with a fraction collector to isolate and quantify individually separated products. This study established systems for the preparation and qualitative and quantitative measurements as well as for the isolation of various sizes of oligomers generated from agarose.

  13. Isolation of immunoglobulin G from bovine milk whey by poly(hydroxyethyl methacrylate)-based anion-exchange cryogel.

    PubMed

    Dong, Shasha; Chen, Liang; Dai, Bin; Johnson, Wilfred; Ye, Jialei; Shen, Shaochuan; Yun, Junxian; Yao, Kejian; Lin, Dong-Qiang; Yao, Shan-Jing

    2013-08-01

    Bovine milk whey contains several bioactive proteins such as α-lactalbumin, β-lactoglobulin, and immunoglobulin G (IgG). Chromatographic separation of these proteins has received much attention in the past few years. In this work, we provide a chromatographic method for the efficient isolation of IgG from bovine milk whey using a poly(2-hydroxyethyl methacrylate)-based anion-exchange cryogel. The monolithic cryogel was prepared by grafting 2-(dimethylamino) ethyl methacrylate onto the poly(2-hydroxyethyl methacrylate)-based cryogel matrix and then employed to separate IgG under various buffer pH and salt elution conditions. The results showed that the buffer pH and the salt concentration in the step elution have remarkable influences on the purity of IgG, while the IgG recovery depended mainly on the loading volume of whey for a given cryogel bed. High purity IgG (more than 95%) was obtained using the phosphate buffer with pH of 5.8 as the running buffer and the salt solution in as the elution liquid. With suitable loading volume of whey, the maximum IgG recovery of about 94% was observed. The present separation method is thus a potential choice for the isolation of high-purity IgG from bovine milk whey.

  14. Simultaneous separation and detection of anions and thiophilic cations using capillary-size anion exchange chromatography with suppressed conductivity detection.

    PubMed

    Sötz, Veronika Anna; Kochmann, Sven

    2015-05-01

    In this fundamental study, the simultaneous separation and detection of anions and thiophilic cations in anion exchange chromatography with suppressed conductivity detection is investigated. Mercury(II) and cadmium(II) served as model analytes. Separation and detection was performed by introducing 2-mercaptoethanesulfonate, which forms complexes with both mercury and cadmium with a strong metal-sulfur bond, into the KOH eluent. Additional to the separation on the column, these complexes were able to pass the suppressor. Subsequently, they could be detected as negative peaks. A simple model for the separation mechanism was developed based on these results. Furthermore, the effect of the eluent concentration on the retention factors of both cation complexes and standard anions was examined and quantified. It revealed that the concentration of 2-mercaptoethanesulfonate has more influence on the cations than the KOH concentration. Also, 2.0 mM of 2-mercaptoethanesulfonate had about the same effect on the anion separation as 60 mM KOH. Finally, selectivity and detection limits were investigated. The detection limits were 4.9 μM for mercury and 2.2 μM for cadmium.

  15. Statins, fibrates, nicotinic acid, cholesterol absorption inhibitors, anion-exchange resins, omega-3 fatty acids: which drugs for which patients?

    PubMed

    Drexel, Heinz

    2009-12-01

    Classes of lipid lowering drugs differ strongly with respect to the types of lipids or lipoproteins they predominantly affect. Statins inhibit the de-novo synthesis of cholesterol. Consequently, the liver produces less VLDL, and the serum concentration primarily of LDL cholesterol (but, to a lesser extent, also of triglycerides) is lowered. Further, statins somewhat increase HDL cholesterol. There is abundant evidence that statins lower the rate of cardiovascular events. Cardiovascular risk reduction is the better, the lower the LDL cholesterol values achieved with statin therapy are. Some evidence is available that anion exchange resins which also decrease LDL cholesterol decrease vascular risk, too. This is not the case for the ezetimibe, which strongly lowers LDL cholesterol: its potential to decrease vascular risk remains to be proven. In contrast evidence for cardiovascular risk reduction through the mainly triglyceride lowering fibrates as well as for niacin is available. Niacin is the most potent HDL increasing drug currently available and besides increasing HDL cholesterol efficaciously lowers triglycerides and LDL cholesterol. Large ongoing trials address the decisive question whether treatment with fibrates and niacin provides additional cardiovascular risk reduction when given in addition to statin treatment.

  16. Framework Cationization by Preemptive Coordination of Open Metal Sites for Anion-Exchange Encapsulation of Nucleotides and Coenzymes.

    PubMed

    Zhao, Xiang; Mao, Chengyu; Luong, Karen Tu; Lin, Qipu; Zhai, Quan-Guo; Feng, Pingyun; Bu, Xianhui

    2016-02-18

    Cationic frameworks can selectively trap anions through ion exchange, and have applications in ion chromatography and drug delivery. However, cationic frameworks are much rarer than anionic or neutral ones. Herein, we propose a concept, preemptive coordination (PC), for targeting positively charged metal-organic frameworks (P-MOFs). PC refers to proactive blocking of metal coordination sites to preclude their occupation by neutralizing ligands such as OH(-) . We use 20 MOFs to show that this PC concept is an effective approach for developing P-MOFs whose high stability, porosity, and anion-exchange capability allow immobilization of anionic nucleotides and coenzymes, in addition to charge- and size-selective capture or separation of organic dyes. The CO2 and C2 H2 uptake capacity of 117.9 cm(3)  g(-1) and 148.5 cm(3)  g(-1) , respectively, at 273 K and 1 atm, is exceptionally high among cationic framework materials.

  17. Mitigating arsenic crisis in the developing world: role of robust, reusable and selective hybrid anion exchanger (HAIX).

    PubMed

    German, Michael; Seingheng, Hul; SenGupta, Arup K

    2014-08-01

    In trying to address the public health crisis from the lack of potable water, millions of tube wells have been installed across the world. From these tube wells, natural groundwater contamination from arsenic regularly puts at risk the health of over 100 million people in South and Southeast Asia. Although there have been many research projects, awards and publications, appropriate treatment technology has not been matched to ground level realities and water solutions have not scaled to reach millions of people. For thousands of people from Nepal to India to Cambodia, hybrid anion exchange (HAIX) resins have provided arsenic-safe water for up to nine years. Synthesis of HAIX resins has been commercialized and they are now available globally. Robust, reusable and arsenic-selective, HAIX has been in operation in rural communities over numerous cycles of exhaustion-regeneration. All necessary testing and system maintenance is organized by community-level water staff. Removed arsenic is safely stored in a scientifically and environmentally appropriate manner to prevent future hazards to animals or people. Recent installations have shown the profitability of HAIX-based arsenic treatment, with capital payback periods of only two years in ideal locations. With an appropriate implementation model, HAIX-based treatment can rapidly scale and provide arsenic-safe water to at-risk populations.

  18. Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane.

    PubMed

    Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

    2016-11-17

    A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl(-)/SO4(2-) separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl(-)/SO4(2-) permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm(2) 30 minutes later.

  19. Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane

    PubMed Central

    Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

    2016-01-01

    A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl−/SO42− separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl−/SO42− permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later. PMID:27853255

  20. Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

    2016-11-01

    A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl‑/SO42‑ separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl‑/SO42‑ permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later.

  1. Anion exchange polymer coated graphite granule electrodes for improving the performance of anodes in unbuffered microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Li, Dengfeng; Mao, Xuhui; Yu, Eileen Hao; Scott, Keith; Zhang, Enren; Wang, Dihua

    2016-10-01

    In this paper, graphite granule composite electrodes are prepared for microbial fuel cells (MFCs) by coating commercial graphite granules with the mixture of quaternary DABCO polysulfone or Nafion ion exchange polymer and carbon black. The results of electrochemical impedance spectroscopy (EIS) suggest that the addition of carbon black could significantly improve the electrical conductivity of graphite granule anodes. When phosphate buffer solution (PBS) is replaced by NaCl solution, the current densities of the pristine anode, 0.08 g Nafion coated anode and 0.16 g QDPSU coated anode decrease by 52.6%, 20.6% and 10.3% at -0.2 V (vs. Ag/AgCl), respectively. The solution resistance of ion exchange polymer coated anodes is more stable in comparison with that of pristine anode. After 40 operational days, the performance drop of 0.16 g QDPSU coated anode when switching the solution from PBS to NaCl is still smaller than that of pristine anode. However, 0.08 g Nafion coated anode shows the similar performance in NaCl solution to the pristine anode after long term operation. This study reveals that QDPSU anion exchange polymer is more suitable for the anode modification. The QDPSU coated anode promises a great potential for three-dimensional anode based MFCs to treat domestic wastewater.

  2. Formation of carbon nanosheets via simultaneous activation and catalytic carbonization of macroporous anion-exchange resin for supercapacitors application.

    PubMed

    Peng, Hui; Ma, Guofu; Sun, Kanjun; Mu, Jingjing; Zhang, Zhe; Lei, Ziqiang

    2014-12-10

    Two-dimensional mesoporous carbon nanosheets (CNSs) have been prepared via simultaneous activation and catalytic carbonization route using macroporous anion-exchange resin (AER) as carbon precursor and ZnCl2 and FeCl3 as activating agent and catalyst, respectively. The iron catalyst in the skeleton of the AER may lead to carburization to form a sheetlike structure during the carbonization process. The obtained CNSs have a large number of mesopores, a maximum specific surface area of 1764.9 m(2) g(-1), and large pore volume of 1.38 cm(3) g(-1). As an electrode material for supercapacitors application, the CNSs electrode possesses a large specific capacitance of 283 F g(-1) at 0.5 A g(-1) and excellent rate capability (64% retention ratio even at 50 A g(-1)) in 6 mol L(-1) KOH. Furthermore, CNSs symmetric supercapacitor exhibits specific energies of 17.2 W h kg(-1) at a power density of 224 W kg(-1) operated in the voltage range of 0-1.8 V in 0.5 mol L(-1) Na2SO4 aqueous electrolyte, and outstanding cyclability (retains about 96% initial capacitance after 5000 cycles).

  3. Renal peroxiredoxin 6 interacts with anion exchanger 1 and plays a novel role in pH homeostasis

    PubMed Central

    Johnstone, Duncan B.; Frankl, Fiona E. Karet

    2015-01-01

    Peroxiredoxin 6 (PRDX6) is one of six members of the PRDX family, which have peroxidase and antioxidant activity. PRDX6 is unique, containing only one conserved cysteine residue (C47) rather than the two found in other PRDXs. A yeast two-hybrid screen found PRDX6 to be a potential binding partner of the C-terminal tail of anion exchanger 1 (AE1), a Cl−/HCO3− exchanger basolaterally expressed in renal α-intercalated cells. PRDX6 immunostaining in human kidney was both cytoplasmic and peripheral and co-localized with AE1. Analysis of native protein showed it was largely monomeric, whereas expressed tagged protein was more dimeric. Two methionine oxidation sites were identified. In vitro and ex vivo pulldowns and immunoprecipitation assays confirmed interaction with AE1, but mutation of the conserved cysteine resulted in loss of interaction. Prdx6 knockout mice had a baseline acidosis with a major respiratory component and greater AE1 expression than wild type animals. After an oral acid challenge, PRDX6 expression increased in wild type mice, with preservation of AE1. However, AE1 expression was significantly decreased in knockout animals. Kidneys from acidified mice showed widespread proximal tubular vacuolation in wild type but not knockout animals. Knockdown of PRDX6 by siRNA in mammalian cells reduced both total and cell membrane AE1 levels. Thus, PRDX6-AE1 interaction contributes to maintenance of AE1 during cellular stress such as during metabolic acidosis. PMID:26398495

  4. Anion-exchange resin-based desulfurization process. Annual technical progress report, October 1, 1991--September 30, 1992

    SciTech Connect

    Sheth, A.C.; Strevel, S.D.; Dharmapurikar, R.

    1992-12-31

    Under the current grant, the University of Tennessee Space Institute (UTSI) will carry out the bench scale evaluation and further development of the anion-exchange resin-based desulfurization concept to desulfurize alkali metal sulfates. This concept has been developed and patented by UTSI under US Patent No. 4,917,874. The developmental program proposed under this DOE grant includes screening of commercially available resins to select three candidate resins for further study. These three resins will undergo a series of experiments designed to test the resins` performance under different process conditions (including the use of spent MHD seed material). The best of these resins will be used in optimizing the regeneration step and in testing the effects of performance enhancers. The process schematic developed from the results will be used to estimate the related economics. During this reporting period, October 1, 1991 to September 30, 1992, analysis of batch mode screening experiments was completed to select three candidate resins for process variables study in the fixed-bed set-up. This setup was modified and the experiments were carded out to evaluate effects of major process variables. The analysis of fixed-bed experiments is going on and we have also started simple batch mode experiments to identify desirable conditions for resin regeneration step. We have also started simple process engineering type calculations to determine the trade-off between the solution concentration and the resulting evaporation/concentration load.

  5. Oxygen evolution reaction characteristics of synthetic nickel-cobalt-oxide electrodes for alkaline anion-exchange membrane water electrolysis

    NASA Astrophysics Data System (ADS)

    Koo, Tae Woo; Park, ChanSu; Kim, Yang Do; Lee, Dooyong; Park, Sungkyun; Lee, Jae Ho; Choi, Sung Mook; Choi, Chul Young

    2015-11-01

    A polymer electrolyte membrane water electrolysis system can produce high-purity hydrogen gases in a highly efficient manner. However, the level of hydrogen gas production is still small. In addition, noble-metal catalysts for the reaction in acidic environments, as well as an additional drying step to remove water contained in the hydrogen, are required. Therefore, water electrolysis system with high efficiency and lower cost, an alkaline anion-exchange membrane system that can produce high-purity hydrogen without a noble-metal catalyst, is needed. Nano-size NiCo2O4 powders were prepared by using a sol-gel method to achieve an efficient and economical water electrolysis system. When the powder was calcined at 450 °C, the crystallinity and the cyclic voltammogram measurement showed the best values. In addition, the 15-wt.% polytetrafluoroethylene mixed NiCo2O4 powders exhibited the largest cyclic voltammetry active area and the highest oxygen evolution reaction activity with the appropriate stability.

  6. Catalytic activity of thiacalix[4]arenetetrasulfonate metal complexes on modified anion-exchangers for ascorbic acid oxidation.

    PubMed

    Odo, Junichi; Hirashima, Tomomi; Hayashida, Tomoko; Miyauchi, Asuka; Minemoto, Mami; Iuchi, Masato; Inoguchi, Masahiko

    2013-01-01

    The catalysis of ascorbic acid (AsA) oxidation by anion-exchangers modified with metal complexes of thiacalix[4]arenetetrasulfonate (Me-TCAS[4]A-500, Me=Mn(3+), Fe(3+), Co(3+), Ce(4+), Cu(2+), Zn(2+), Ni(2+), and H2) were investigated. Me-TCAS[4]A-500 (Me=Mn(3+), Fe(3+), Ce(4+), and Cu(2+)) all exhibited the ability to catalyze the oxidative reaction of AsA to dehydroascorbic acid. However, in the presence of high concentrations of AsA, only Cu(2+)-TCAS[4]A-500 was capable of complete oxidation of the acid. Moreover, after six repeat uses, Cu(2+)-TCAS[4]A-500 maintained high and relatively constant catalytic activity. Prior treatment of glucose solutions with Cu(2+)-TCAS[4]A-500, even in the presence of high AsA concentrations, enabled the satisfactory determination of glucose without interference by AsA. Cu(2+)-TCAS[4]A-500 will therefore be applicable as an artificial substitute for ascorbate oxidase, and may be useful as a means to eliminate AsA interference during the analysis of vital compounds such as glucose and uric acid.

  7. Determination of 129I in environmental samples by AMS and NAA using an anion exchange resin disk

    NASA Astrophysics Data System (ADS)

    Suzuki, Takashi; Banba, Shigeru; Kitamura, Toshikatsu; Kabuto, Shoji; Isogai, Keisuke; Amano, Hikaru

    2007-06-01

    We have developed a new extraction method for the measurement of 129I by accelerator mass spectrometry (AMS) utilizing an anion exchange resin disk. In comparison to traditional methods such as solvent extraction and ion exchange, this method provides for simple and quick sample handling. This extraction method was tested on soil, seaweed and milk samples, but because of disk clogging, the milk samples and some of the seaweed could not be applied successfully. Using this new extraction method to prepare samples for AMS analysis produced isotope ratios of iodine in good agreement with neutron activation analysis (NAA). The disk extraction method which take half an hour is faster than previous techniques, such as solvent extraction or ion exchange which take a few hours. The combination of the disk method and the AMS measurement is a powerful tool for the determination of 129I. Furthermore, these data will be available for the environmental monitoring before and during the operation of a new nuclear fuel reprocessing plant in Japan.

  8. Assemblies of protective anion exchange membrane on air electrode for its efficient operation in aqueous alkaline electrolyte

    NASA Astrophysics Data System (ADS)

    Bertolotti, Bruno; Chikh, Linda; Vancaeyzeele, Cédric; Alfonsi, Séverine; Fichet, Odile

    2015-01-01

    Aqueous alkaline metal-air batteries represent promising energy storage devices when supplied with atmospheric air. However, under this condition, the air electrode shows a very short life time (i.e. 50 h of operation in 5 M LiOH at -10 mA cm-2), mainly due to the precipitation of carbonates inside the electrode porosity. The air electrode can then be protected by an anion exchange membrane on the electrolyte side. In this paper, we demonstrate that the efficiency of this protective membrane depends on the assembly method on the electrode. When a modified poly(epichlorohydrin) (PECH) network is synthesized directly on the electrode, the polymer seeps inside the electrode porosity, and a suitable interface inducing negligible additional polarization in comparison with classical pressure-assembled membranes is obtained. This protected electrode shows improved stability of up to 160 h of operation in 5 M LiOH. This performance is improved to 350 h by adjusting the conductivity and the ionic exchange capacity. Finally, the interest of interpenetrating polymer network (IPN) architecture compared to a single network is confirmed. Indeed, an electrode protected with a PECH/poly(2-hydroxyethyl methacrylate) (PHEMA) IPN is stable for 650 h in 5 M LiOH. In addition, degradation process becomes reversible since the assembly can be regenerated, which is not possible for the bare electrode.

  9. In and ex situ characterization of an anion-exchange membrane for alkaline direct methanol fuel cell (ADMFC)

    NASA Astrophysics Data System (ADS)

    Santasalo-Aarnio, Annukka; Hietala, Sami; Rauhala, Taina; Kallio, Tanja

    2011-08-01

    Anion exchange membrane fumasep® FAA-2 was characterized with ex and in situ methods in order to estimate the membranes' suitability as an electrolyte for an alkaline direct methanol fuel cell (ADMFC). The interactions of this membrane with water, hydroxyl ions and methanol were studied with both calorimetry and NMR and compared with the widely used proton exchange membrane Nafion® 115. The results indicate that FAA-2 has a tighter structure and more homogeneous distribution of ionic groups in contrast to the clustered structure of Nafion, moreover, the diffusion of OH- ions through this membrane is clearly slower compared to water molecules. The permeability of methanol through the FAA-2 membrane was found to be an order of magnitude lower than for Nafion. Fuel cell experiments in 1 mol dm-3 methanol with FAA-2 resulted in OCV of 0.58 V and maximum power density of 0.32 mW cm-2. However, even higher current densities were obtained with highly concentrated fuels. This implies that less water is needed for fuel dilution, thereby decreasing the mass of the fuel cell system. In addition, electrochemical impedance spectroscopy for the ADMFC was used to determine ohmic resistance of the cell facilitating the further membrane development.

  10. Cross-linked anion exchange membranes with pendent quaternary pyrrolidonium salts for alkaline polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lan, Chunhua; Fang, Jun; Guan, Yingjie; Zhou, Huili; Zhao, Jinbao

    2015-11-01

    Novel anion-exchange membranes based on two kinds of pyrrolidonium type ionic liquids, N-methyl-N-vinyl-pyrrolidonium (NVMP) and N-ethyl-N-vinyl-pyrrolidonium (NVEP), have been synthesized via polymerization and crosslinking treatment, followed by membrane casting. The covalent cross-linked structures of these membranes are confirmed by FT-IR. The obtained membranes are also characterized in terms of water uptake, ion exchange capacity (IEC), ionic conductivity as well as thermal, dimensional and chemical stability. The membranes display hydroxide conductivity of above 10-2 S cm-1 at 25 °C. Excellent thermal stability with onset degradation temperature above 235 °C, good alkaline stability in 6 mol L-1 NaOH at 60 °C for 168 h and remarkable dimensional stability of the resulting membranes have been proved. H2/air single fuel cells employed membrane M3 and N3 show the open-circuit voltage (OCV) of 0.953 V and 0.933 V, and the maximum power density of 88.90 mW cm-2 and 81.90 mW cm-2 at the current density of 175 mA cm-2 and 200 mA cm-2 at 65 °C, respectively.

  11. Synthesis and performance of novel anion exchange membranes based on imidazolium ionic liquids for alkaline fuel cell applications

    NASA Astrophysics Data System (ADS)

    Fang, Jun; Lyu, Ming; Wang, Xin; Wu, Yongbin; Zhao, Jinbao

    2015-06-01

    Novel anion exchange membranes (AEMs) based on two types of imidazolium ionic liquids, 1-vinyl-3-methylimidazolium iodide [VMI]I and 1-vinyl-3-butylimidazolium bromide [VBI]Br, have been synthesized by copolymerization. The obtained membranes are characterized in terms of water uptake, ion exchange capacity (IEC), ionic conductivity as well as thermal and chemical stability. The conductivity reaches 0.0226 Scm-1 at 30 °C. All the membranes show excellent thermostability. The membranes are stable in 10 mol L-1 NaOH solution at 60 °C for 120 h without obvious changes in ion conductivity. Fuel cell performance using the resulting membrane has been investigated. The open circuit voltage (OCV) of the H2/O2 fuel cell is 1.07 V. A peek power density of 116 mW cm-2 is obtained at a current density of 230 mA cm-2 at 60 °C. The results demonstrate the brilliant prospect of the developed membranes for alkaline fuel cell applications.

  12. A semi-interpenetrating network approach for dimensionally stabilizing highly-charged anion exchange membranes for alkaline fuel cells.

    PubMed

    He, Steve S; Strickler, Alaina L; Frank, Curtis W

    2015-04-24

    There is a delicate balance between ion exchange capacity (IEC), conductivity, and dimensional stability in anion exchange membranes as higher charge content can lead to increased water uptake, causing excessive swelling and charge dilution. Using highly-charged benzyltrimethylammonium polysulfone (IEC=2.99 mEq g(-1) ) as a benchmark (which ruptured in water even at room temperature), we report the ability to dramatically decrease water uptake using a semi-interpenetrating network wherein we reinforced the linear polyelectrolyte with a crosslinked poly(styrene-co-divinylbenzene) network. These membranes show enhanced dimensional stability as a result of lower water uptake (75 % vs. 301 % at 25 °C) while maintaining excellent hydroxide conductivity (up to 50 mS cm(-1) at 25 °C). These improvements produced an enhanced alkaline fuel cell capable of generating 236 mW cm(-2) peak power density at 80 °C. This method is easily adaptable and can be a viable strategy for stabilizing existing systems.

  13. Highly stable pyridinium-functionalized cross-linked anion exchange membranes for all vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Zeng, L.; Zhao, T. S.; Wei, L.; Zeng, Y. K.; Zhang, Z. H.

    2016-11-01

    It has recently been demonstrated that the use of anion exchange membranes (AEMs) in vanadium redox flow batteries (VRFBs) can reduce the migration of vanadium ions through the membrane due to the Donnan exclusion effect among the positively charged functional groups and vanadium ions. However, AEMs are plagued by low chemical stability in harsh chemical environments. Here we propose and fabricate a pyridinium-functionalized cross-linked AEM for VRFBs. The pyridinium-functionalized bromomethylated poly (2,6-dimethyl-1,4-phenylene oxide) exhibits a superior chemical stability as a result of the strengthened internal cross-linking networks and the chemical inertness of the polymer backbone. Therefore, the membrane exhibits littler decay in a harsh environment for 20 days during the course of an ex situ immersion test. A cycling test also demonstrates that the VRFB assembled with the membrane enable to retain 80% of the initial discharge capacity over 537 cycles with a capacity decay rate of 0.037% cycle-1. Meanwhile, the membrane also shows a low vanadium permeability and a reasonably high conductivity in supporting electrolytes. Hence, all the measurements and performance tests reported in this work suggest that the membrane is a promising AEM for redox flow batteries to achieve excellent cycling stability and superior cell performance.

  14. Quantitative determination of saccharides in dietary glyconutritional products by anion-exchange liquid chromatography with integrated pulsed amperometric detection.

    PubMed

    Eberendu, Alexis R; Booth, Christy; Luta, Gabriela; Edwards, Joshua A; McAnalley, Bill H

    2005-01-01

    A new technique for the assay of carbohydrates is described in which separation and quantification of neutral saccharides, aminosaccharides, glycuronic acids, and disaccharides may be accomplished in less than 50 min of total run time. This method involves optimized anion-exchange liquid chromatography coupled with integrated pulse amperometric detection. Complex carbohydrates from various sources, including dietary supplements, were hydrolyzed in a dilute solution of trifluoroacetic acid, freeze-dried, and reconstituted in water containing 2-deoxygalactose as the internal standard. The solution was filtered and separated on CarboPac PA20 column. The eluted saccharides were detected by oxidation on a gold electrode with quadruple-pulsed integrated amperometry. The calibration plots for the saccharides were linear with an average correlation coefficient of 0.999. Method precision regarding peak retention time and resolution used in the peak identifications was verified. With this method, previously difficult-to-separate saccharides, such as galactosamine, glucosamine, and N-acetylglucosamine, were successfully resolved from the neutral saccharides rhamnose, arabinose, and galactose. Mannose was also resolved from xylose, and de-acetylation of aminosaccharides prior to separation was not necessary. This technique provides an accurate and efficient means to assay carbohydrates in dietary supplements, which new federal regulations will soon mandate.

  15. Assay for inorganic pyrophosphate in chondrocyte culture using anion-exchange high-performance liquid chromatography and radioactive orthophosphate labeling

    SciTech Connect

    Prins, A.P.; Kiljan, E.; v.d. Stadt, R.J.; v.d. Korst, J.K.

    1986-02-01

    A method is described for determination of inorganic pyrophosphate (PPi) in cell culture medium and in rabbit articular chondrocytes grown in the presence of radioactive orthophosphate (/sup 32/Pi). Intra- and extracellular /sup 32/PPi formed was measured using high-performance liquid chromatographic (HPLC) separation of the PPi from orthophosphate (Pi) and other phosphate-containing compounds. The chromatographic separation on a weak anion-exchange column is based on the extent to which various phosphate compounds form complexes with Mg2+ at low pH and the rate at which such formation occurs. These complexes are eluted more readily than the uncomplexed compounds. Best results were obtained using a simultaneous gradient of Mg2+ ions and ionic strength. In this case separation of small amounts of PPi from a large excess of Pi was possible without prior removal of Pi or extraction of the PPi fraction. The assay is also useful for measurement of inorganic pyrophosphatase activity. The sensitivity of the assay depends on the specific activity of the added /sup 32/Pi and on the culture conditions, but is comparable with the most sensitive of the enzymatic assays. Sample preparation, particularly deproteinization, proved to be of importance. The losses of PPi which occur during procedures of this sort due to hydrolysis and coprecipitation were quantitated.

  16. Improvement of sugar analysis sensitivity using anion-exchange chromatography-electrospray ionization mass spectrometry with sheath liquid interface.

    PubMed

    Xu, Xian-Bing; Liu, Ding-Bo; Guo, Xiao Ming; Yu, Shu-Juan; Yu, Pei

    2014-10-31

    A novel interface that enables high-performance anion-exchange chromatography (HPAEC) to be coupled with electrospray ionization (ESI) mass spectrometry (MS) is reported. A sheath liquid consisting of 50mM NH4Ac in isopropanol with 0.05% acetic acid, infused at a flow rate of 3μL/min at the tip of the electrospray probe, requires less ESI source cleaning and promotes efficient ionization of mono- and di-carbohydrates. The results suggest that use of a sheath liquid interface rather than a T-joint allows volatile ammonium salts to replace non-volatile metal salts as modifiers for improving sugar ESI signals. The efficient ionization of mono- and di-carbohydrates in the ESI source is affected by the sheath liquid properties such as buffer concentration and type of organic solvent. HPAEC-ESI-MS was used for the analysis of monocarbohydrates in pectins, particularly co-eluted sugars, and the performance was evaluated. Addition of a make-up solution through the sheath liquid interface proved to be an efficient tool for enhancing the intensities of sugars analyzed using HPAEC-ESI-MS.

  17. Determination of saccharides in atmospheric aerosol using anion-exchange high-performance liquid chromatography and pulsed-amperometric detection.

    PubMed

    Caseiro, Alexandre; Marr, Iain L; Claeys, Magda; Kasper-Giebl, Anne; Puxbaum, Hans; Pio, Casimiro A

    2007-11-09

    An improved method is described for the quantification of primary sugars, sugar alcohols and anhydrosugars in atmospheric aerosols, making use of separation by high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection (PAD). Quartz fibre filters from high-volume samplers were extracted with water and the extract injected directly. Repeatability is typically 4% RSD, for e.g. levoglucosan at 50 ng m(-3) in air, better for winter levels around 700 ng m(-3). Limits of detection for individual sugars are in the range 0.02-0.05 microg mL(-1) in solution, corresponding to 2-5 ng m(-3) from a 20 m(3) air sample. The overlap of arabitol and levogluocosan is overcome by using a Dionex PA-1 column, with appropriate control of eluent composition, and peak deconvolution software, allowing quantification of both sugars in difficult summer samples containing low-levels of levoglucosan. Analysis of a set of ambient aerosol samples by both GC-flame ionization detection and HPAEC-PAD shows good agreement. The new method has the advantage of requiring no sample pretreatment or derivatization and is thus well suited to handling large numbers of samples.

  18. Arsenic(V) removal from aqueous solutions using an anion exchanger derived from coconut coir pith and its recovery.

    PubMed

    Anirudhan, T S; Unnithan, Maya R

    2007-01-01

    The performance of a new anion exchanger (AE) prepared from coconut coir pith (CP), for the removal of arsenic(V) [As(V)] from aqueous solutions was evaluated in this study. The adsorbent (CP-AE) carrying dimethylaminohydroxypropyl weak base functional group was synthesized by the reaction of CP with epichlorohydrin and dimethylamine followed by treatment of hydrochloric acid. IR spectroscopy results confirm the presence of -NH(+)(CH(3))(2)Cl(-) group in the adsorbent. XRD studies confirm the decrease of crystallinity in CP-AE compared to CP, and it favours the protrusion of the functional group into the aqueous medium. Batch experiments were conducted to examine the efficiency of the adsorbent on As(V) removal. Maximum removal of 99.2% was obtained for an initial concentration of 1 mgl(-1) As(V) at pH 7.0 and an adsorbent dose of 2 gl(-1). The kinetics of sorption of As(V) onto CP-AE was described using the pseudo-second-order model. The equilibrium isotherms were determined for different temperatures and the results were analysed using the Langmuir equation. The temperature dependence indicates an exothermic process. Utility of the adsorbent was tested by removing As(V) from simulated groundwater. Regeneration studies were performed using 0.1N HCl. Batch adsorption-desorption studies illustrate that CP-AE could be used to remove As(V) from ground water and other industrial effluents.

  19. Removal of Cr(VI) and As(V) ions from aqueous solutions by polyacrylate and polystyrene anion exchange resins

    NASA Astrophysics Data System (ADS)

    Jachuła, Justyna; Hubicki, Zbigniew

    2013-09-01

    The sorption of Cr(VI) and As(V) from the aqueous solutions with the polyacrylate anion exchangers of the strong base functional groups Amberlite IRA 458 and Amberlite IRA 958 was studied. The studies were carried out by the static-batch method. The concentration of Cr(VI) and As(V) ions in the aqueous solution was determined by the UV-VIS spectrophotometer. The influence of several parameters was studied with respect to sorption equilibrium. The phase contact time and the concentration affect the sorption process. The equilibrium state was established already after 15 min of phase contact time. Maximum uptake of Cr(VI) and As(V) occurred at pH 5 and 10, respectively. The determined kinetic parameters imply that the sorption process proceeds according to the equation type of pseudo second-order. Sorption equilibrium data were correlated with the Langmuir and Freundlich isotherms. Removal of As(V) ions on macroporous Amberlite IRA 900 decreased about 12 % in presence of other anions (Cl-, NO3 -, SO4 2-) in the solution. The sorption was temperature dependent.

  20. Quantification of genetically modified soya using strong anion exchange chromatography and time-of-flight mass spectrometry.

    PubMed

    Chang, Po-Chih; Reddy, P Muralidhar; Ho, Yen-Peng

    2014-09-01

    Stable-isotope dimethyl labeling was applied to the quantification of genetically modified (GM) soya. The herbicide-resistant gene-related protein 5-enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) was labeled using a dimethyl labeling reagent, formaldehyde-H2 or -D2. The identification and quantification of CP4 EPSPS was performed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The CP4 EPSPS protein was separated from high abundance proteins using strong anion exchange chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Then, the tryptic peptides from the samples and reference were labeled with formaldehyde-H2 and formaldehyde-D2, respectively. The two labeled pools were mixed and analyzed using MALDI-MS. The data showed a good correlation between the peak ratio of the H- and D-labeled peptides and the GM soya percentages at 0.5, 1, 3, and 5 %, with R (2) of 0.99. The labeling reagents are readily available. The labeling experiments and the detection procedures are simple. The approach is useful for the quantification of GM soya at a level as low as 0.5 %.

  1. The oxidative degradation of polystyrene resins on the removal of Cr(VI) from wastewater by anion exchange.

    PubMed

    Xiao, Ke; Xu, Fuyuan; Jiang, Linhua; Dan, Zhigang; Duan, Ning

    2016-08-01

    Cr(VI) is a powerful oxidant and is capable of oxidizing most of the organic materials. Therefore, it is possible for Cr(VI) to oxidize the polymeric resins and change the sorption properties of the resins on the removal of Cr(VI) from wastewater by anion exchange. In this study, three polystyrene resins (D201, D202, and D301) with different functional groups (-N(+)(CH3)3, -N(+)(CH3)2(C2H4OH), and N(CH3)2) were assessed on oxidation stability for Cr(VI) removal from wastewater in fixed-bed column experiments. After a 10-cycle operation, due to the oxidation of the resin, the sorption capacity of D201, D202, and D301 resins decreased by 23.5, 29.3, and 17.3%, when approximately 20-34%, 31-50%, and 18-30% of Cr(VI) was reduced to Cr(III) during each cycle respectively. The results of the Fourier transform infrared spectroscopy (FT-IR) showed that both the cleavage of CN and the formation of CO bonds occurred on the polystyrene resins during the Cr(VI) removal process. The resin simulation experiments further validated the oxidation of CC and CN bonds connected with phenethyl groups. Based upon the results from column operations and the resin simulated experiments, the oxidation mechanism of the polystyrene resin was proposed.

  2. Effect of dissolved organic matter on nitrate-nitrogen removal by anion exchange resin and kinetics studies.

    PubMed

    Song, Haiou; Yao, Zhijian; Wang, Mengqiao; Wang, Jinnan; Zhu, Zhaolian; Li, Aimin

    2013-01-01

    The effects of dissolved organic matter (DOM) on the removal of nitrate-nitrogen from the model contaminated water have been investigated utilizing the strong base anion exchange resins. With the increase of gallic acid concentration from 0 to 400 mg/L, the adsorption amount of nitrate-nitrogen on the commercial resins, including D201, Purolite A 300 (A300) and Purolite A 520E (A520E), would significantly decrease. However, the presence of tannin acid has little impact on nitrate-nitrogen adsorption on them.Compared to D201 and A300 resins, A520E resin exhibited more preferable adsorption ability toward nitrate-nitrogen in the presence of competing organic molecules, such as gallic acid and tannin acid at greater levels in aqueous solution. Attractively, the equilibrium data showed that the adsorption isotherm of nitrate-nitrogen on A520E resin was in good agreement with Langmuir and Freundlich equations. The rate parameters for the intra particle diffusion have been estimated for the different initial concentrations. In batch adsorption processes, nitrate-nitrogen diffuse in porous adsorbent and rate process usually depends on t1/2 rather than the contact time. The pseudo first- and the second-order kinetic models fit better for nitrate-nitrogen adsorption onto A520E resin. The observations reported herein illustrated that A520E resin will be an excellent adsorbent for enhanced removal of nitrate-nitrogen from contaminated groundwater.

  3. Electrochemical and fuel cell evaluation of Co based catalyst for oxygen reduction in anion exchange polymer membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Mamlouk, M.; Kumar, S. M. Senthil; Gouerec, Pascal; Scott, Keith

    Co based catalyst were evaluated for oxygen reduction (ORR) in liquid KOH and alkaline anion exchange membrane fuel cells (AAEMFCs). In liquid KOH solution the catalyst exhibited good performance with an onset potential 120 mV more negative than platinum and a Tafel slope of ca. 120 mV dec -1. The hydrogen peroxide generated, increased from 5 to 50% as the electrode potential decreased from 175 to -300 mV vs. SHE. In an AAEMFC environment, one catalyst (GP2) showed promising performance for ORR, i.e. at 50 mA cm -2 the differences in cell potential between the stable performance for platinum (more positive) and cobalt cathodes with air and oxygen, were only 45 and 67 mV respectively. The second catalyst (GP4) achieved the same stable power density as with platinum, of 200 and 145 mW cm -2, with air at 1 bar (gauge) pressure and air (atm) cathode feed (60 °C), respectively. However the efficiency was lower (i.e. cell voltage was lower) i.e. 40% in comparison to platinum 47.5%.

  4. Quaternized adamantane-containing poly(aryl ether ketone) anion exchange membranes for vanadium redox flow battery applications

    NASA Astrophysics Data System (ADS)

    Zhang, Bengui; Zhang, Shouhai; Weng, Zhihuan; Wang, Guosheng; Zhang, Enlei; Yu, Ping; Chen, Xiaomeng; Wang, Xinwei

    2016-09-01

    Quaternized adamantane-containing poly(aryl ether ketone) anion exchange membranes (QADMPEK) are prepared and investigated for vanadium redox flow batteries (VRFB) application. The bulky, rigid and highly hydrophobic adamantane segment incorporated into the backbone of membrane material makes QADMPEK membranes have low water uptake and swelling ratio, and the as-prepared membranes display significantly lower permeability of vanadium ions than that of Nafion117 membrane. As a consequence, the VRFB cell with QADMPEK-3 membrane shows higher coulombic efficiency (99.4%) and energy efficiency (84.0%) than those for Nafion117 membrane (95.2% and 80.5%, respectively) at the current density of 80 mA cm-2. Furthermore, at a much higher current density of 140 mA cm-2, QADMPEK membrane still exhibits better coulombic efficiency and energy efficiency than Nafion117 membrane (coulombic efficiency 99.2% vs 96.5% and energy efficiency 76.0% vs 74.0%). Moreover, QADMPEK membranes show high stability in in-situ VRFB cycle test and ex-situ oxidation stability test. These results indicate that QADMPEK membranes are good candidates for VRFB applications.

  5. Vacancy ion-exclusion/adsorption chromatography of aliphatic amines on a polymethacrylate-based weakly basic anion-exchange column.

    PubMed

    Mori, Masanobu; Helaleh, Murad I H; Xu, Qun; Hu, Wenzhi; Ikedo, Mikaru; Ding, Ming-Yu; Taoda, Hiroshi; Tanaka, Kazuhiko

    2004-06-11

    Vacancy ion-exclusion/adsorption chromatography has been applied to investigate the separation behavior of five aliphatic amines (ethylamine, propylamine, butylamine, pentylamine and hexylamine) on a polymethacrylate-based weakly basic anion-exchange column (Tosoh TSKgel DEAE-5PW). This system is consisted of analytes as a mobile phase and water as an injected sample. In the vacancy ion-exclusion/adsorption chromatography, the elution order was as follows: ethylamine < propylamine < butylamine < pentylamine < hexylamine, depending on their hydrophobicity. The retention times of the amines were decreased with decreasing their concentrations in the mobile phase. The retention times and resolutions of the amines were increased by adding a basic compound (e.g., lithium hydroxide or heptylamine) and by increasing the pH of mobile phase (pH > 11). This was because the dissociations of amine samples in the mobile phase were suppressed and thus the hydrophobic adsorption effects were enhanced. The linearity of calibration graphs could be obtained from the peak areas of the amine samples injected to the 0.05, 0.5 and 5 mM of amine mobile phase at pH 11 by heptylamine. The detection limits of aliphatic amines as injected samples were around 1 microM for five aliphatic amines at three different amine mobile phases. From these results, the retention behaviors of aliphatic amines on vacancy ion-exclusion/adsorption chromatography were concluded to be governed by the hydrophobic adsorption effect.

  6. Improved electrical power production of thermally regenerative batteries using a poly(phenylene oxide) based anion exchange membrane

    NASA Astrophysics Data System (ADS)

    Rahimi, Mohammad; Zhu, Liang; Kowalski, Kelly L.; Zhu, Xiuping; Gorski, Christopher A.; Hickner, Michael A.; Logan, Bruce E.

    2017-02-01

    Thermally regenerative ammonia-based batteries (TRABs) can be used to harvest low-grade waste heat as electrical power. To improve TRAB performance, a series of benzyltrimethyl quaternary ammonium-functionalized poly(phenylene oxide) anion exchange membranes (BTMA-AEMs) were examined for their impact on performance relative to a commercial AEM (Selemion AMV). The synthesized AEMs had different degrees of functionalization (DF; 25% and 40%), and thicknesses (50, 100 and 150 μm). Power and energy densities were shown to be a function of both DF and membrane thickness. The power density of TRAB increased by 31% using a BTMA-AEM (40% DF, 50 μm thick; 106 ± 7 W m-2) compared to the Selemion (81 ± 5 W m-2). Moreover, the energy density increased by 13% when using a BTMA-based membrane (25% DF, 150 μm thick; 350 Wh m-3) compared to the Selemion membrane (311 Wh m-3). The thermal-electric conversion efficiency improved to 0.97% with the new membrane compared to 0.86% for the Selemion. This energy recovery was 7.0% relative to the Carnot efficiency, which was 1.8 times greater than the highest previously reported value of a system used to capture low-grade waste heat as electricity.

  7. Chitosan Derivatives as Important Biorefinery Intermediates. Quaternary Tetraalkylammonium Chitosan Derivatives Utilized in Anion Exchange Chromatography for Perchlorate Removal

    PubMed Central

    Sayed, Shakeela; Jardine, Anwar

    2015-01-01

    There has recently been great interest in the valorization of biomass waste in the context of the biorefinery. The biopolymer chitosan, derived from chitin, is present in large quantities of crustacean waste. This biomass can be converted into value-added products with applications in energy, fuel, chemicals and materials manufacturing. The many reported applications of this polymer can be attributed to its unique properties, such as biocompatibility, chemical versatility, biodegradability and low toxicity. Cost effective water filters which decontaminate water by removal of specific impurities and microbes are in great demand. To address this need, the development of ion exchange resins using environmentally friendly, renewable materials such as biopolymers as solid supports was evaluated. The identification and remediation of perchlorate contaminated water using an easy, inexpensive method has come under the spotlight recently. Similarly, the use of a low cost perchlorate selective solid phase extraction (SPE) cartridge that can be rapidly employed in the field is desirable. Chitosan based SPE coupled with colorimetric analytical methods showed promise as a renewable anion exchange support for perchlorate analysis or removal. The polymers displayed perchlorate retention comparable to the commercial standard whereby the quaternized iron loaded polymer TMC-Fe(III) displayed the best activity. PMID:25915024

  8. Kinetics and Mechanism of the Sorption of Some Aromatic Amines onto Amberlite IRA-904 Anion-Exchange Resin.

    PubMed

    Zaki; El-Sheikh; Evans; El-Safty

    2000-01-01

    The kinetics of the sorption of aromatic amines such as o-aminophenol (o-AP), o-phenylenediamine (o-PDA), and p-phenylenediamine (p-PDA) onto Amberlite anion-exchange resin in chloride form was investigated in batch experiments spectrophotometrically at different temperatures. The sorption rate is zero order in all amines sorbed, increasing directly in the order: p-PDA

  9. How pulse modes affect proton-barriers and anion-exchange membrane mineral fouling during consecutive electrodialysis treatments.

    PubMed

    Cifuentes-Araya, Nicolás; Pourcelly, Gérald; Bazinet, Laurent

    2013-02-15

    Mineral fouling of cation-exchange membrane (CEM) was recently reduced by pulsed electric fields (PEFs) during the electrodialysis (ED) of solutions containing high Mg(2+)/Ca(2+) ratios. However, a fouling layer appeared on the diluate side of anion-exchange membrane (AEM) once the pause lapse surpassed certain duration. Recent studies presented a multilayer mineral growth on CEM, but the case of AEM needs yet to be cleared. The current study reveals the mechanisms involved in AEM fouling growth when applying pulse modes of current in comparison with dc current. The results showed that dc current generated steady proton barriers given by water splitting at AEM interfaces that impeded fouling on both membrane sides. The higher frequency of PEF ratio 1 (Ton/Toff=10s/10s) acted removing completely an initial mineral deposit on the concentrate side of AEM, keeping it clean after two and three consecutive runs. Particularly, an undesirable brucite layer was formed on the AEM-diluate side for longer pause lapses as for a PEF ratio 0.3 (Ton/Toff=10s/33.3s) current regime. This structure caused violent water splitting resulting in amorphous magnesium hydroxide formation and consequently in fouling precipitation on the concentrate side during a third run through current exaltation.

  10. Dissolved organic matter removal using magnetic anion exchange resin treatment on biological effluent of textile dyeing wastewater.

    PubMed

    Fan, Jun; Li, Haibo; Shuang, Chendong; Li, Wentao; Li, Aimin

    2014-08-01

    This study investigated the removal of dissolved organic matter (DOM) from real dyeing bio-treatment effluents (DBEs) with the use of a novel magnetic anion exchange resin (NDMP). DOMs in two typical DBEs were fractionized using DAX-8/XAD-4 resin and ultrafiltration membranes. The hydrophilic fractions and the low molecular weight (MW) (<3kDa) DOM fractions constituted a major portion (>50%) of DOMs for the two effluents. The hydrophilic and low MW fractions of both effluents were the greatest contributors of specific UV254 absorbance (SUVA254), and the SUVA254 of DOM fractions decreased with hydrophobicity and MW. Two DBEs exhibited acute and chronic biotoxicities. Both acute and chronic toxicities of DOM fractions increased linearly with the increase of SUVA254 value. Kinetics of dissolved organic carbon (DOC) removal via NDMP treatment was performed by comparing it with that of particle active carbon (PAC). Results indicated that the removal of DOC from DBEs via NDMP was 60%, whereas DOC removals by PAC were lower than 15%. Acidic organics could be significantly removed with the use of NDMP. DOM with large MW in DBE could be removed significantly by using the same means. Removal efficiency of NDMP for DOM decreased with the decrease of MW. Compared with PAC, NDMP could significantly reduce the acute and chronic bio-toxicities of DBEs. NaCl/NaOH mixture regenerants, with selected concentrations of 10% NaCl (m/m)/1% NaOH (m/m), could improve desorption efficiency.

  11. Removal of radioactive caesium from low level radioactive waste (LLW) streams using cobalt ferrocyanide impregnated organic anion exchanger.

    PubMed

    Valsala, T P; Roy, S C; J G Shah; Gabriel, J; Raj, Kanwar; Venugopal, V

    2009-07-30

    The volumes of low level waste (LLW) generated during the operation of nuclear reactor are very high and require a concentration step before suitable matrix fixation. The volume reduction (concentration) is achieved either by co-precipitating technique or by the use of highly selective sorbents and ion exchange materials. The present study details the preparation of cobalt ferrocyanide impregnated into anion exchange resin and its evaluation with respect to removal of Cs in LLW streams both in column mode and batch mode operations. The Kd values of the prepared exchanger materials were found to be very good in actual reactor LLW solutions also. It was observed that the exchanger performed very well in the pH range of 3-9. A batch size of 6 g l(-1) of the exchanger was enough to give satisfactory decontamination for Cs in actual reactor LLW streams. The lab scale and pilot plant scale performance of the exchanger material in both batch mode and column mode operations was very good.

  12. [Simultaneous analysis of trehalose, glucose and maltose in biotransformation samples by high performance anion exchange chromatography with pulsed ampere detection].

    PubMed

    Xu, Ying; Zang, Ying; Jiang, Ting; Zheng, Zhaojuan; Quyang, Jia

    2014-12-01

    An analytical method for the determination of trehalose, maltose, and glucose in biotransformation samples was developed by using high performance anion exchange chromatography coupled with pulsed ampere detection (HPAEC-PAD). The analysis was performed on a CarboPac™ 10 column (250 mm x 2 mm) with the gradient elution of NaOH-NaAc as the mobile phase. The column temperature was set at 30 °C, the flow rate was 0. 30 mL/min. The results showed that trehalose, maltose, and glucose in biotransformation system were completely separated and determined in 15 min. The linear ranges and the working curves were determined by using standard samples. The correlation coefficients of three kinds of carbohydrates were over 0. 9998 . The detection limits (LODs) were 0. 010 - 0. 100 mg/L. Under the optimized separation conditions, the recoveries of saccharides in the transformation system at three different spiked levels ranged from 89. 4% to 103. 2%. In biotransformation system, 50 IU trehalose synthase were added into 200 g/L maltose for reaction of 8 h at 37 °C, pH 8. 0. Under the above conditions, the concentration of trehalose in biotransformation sample was 101. 084 g/L, and the conversion rate of trehalose reached 50. 5%. The method can be applied to determine the composition in the transformation system with the advantages of simplicity and convenience.

  13. Characterization of At- species in simple and biological media by high performance anion exchange chromatography coupled to gamma detector.

    PubMed

    Sabatié-Gogova, A; Champion, J; Huclier, S; Michel, N; Pottier, F; Galland, N; Asfari, Z; Chérel, M; Montavon, G

    2012-04-06

    Astatine is a rare radioelement belonging to the halogen group. Considering the trace amounts of astatine produced in cyclotrons, its chemistry cannot be evaluated by spectroscopic tools. Analytical tools, provided that they are coupled with a radioactive detection system, may be an alternative way to study its chemistry. In this research work, high performance anion exchange chromatography (HPAEC) coupled to a gamma detector (γ) was used to evaluate astatine species under reducing conditions. Also, to strengthen the reliability of the experiments, a quantitative analysis using a reactive transport model has been done. The results confirm the existence of one species bearing one negative charge in the pH range 2-7.5. With respect to the other halogens, its behavior indicates the existence of negative ion, astatide At(-). The methodology was successfully applied to the speciation of the astatine in human serum. Under fixed experimental conditions (pH 7.4-7.5 and redox potential of 250 mV) astatine exists mainly as astatide At(-) and does not interact with the major serum components. Also, the method might be useful for the in vitro stability assessment of (211)At-labeled molecules potentially applicable in nuclear medicine.

  14. Optimization of RNA Purification and Analysis for Automated, Pre-Symptomatic Disease Diagnostics

    SciTech Connect

    Vaidya, A; Nasarabadi, S; Milanovich, F

    2005-06-28

    When diagnosing disease, time is often a more formidable enemy than the pathogen itself. Current detection methods rely primarily on post-symptomatic protein production (i.e. antibodies), which does not occur in noticeable levels until several weeks after infection. As such, a major goal among researchers today is to expedite pre-symptomatic disease recognition and treatment. Since most pathogens are known to leave a unique signature on the genetic expression of the host, one potential diagnostic tool is host mRNA. In my experiments, I examined several methods of isolating RNA and reading its genetic sequence. I first used two types of reverse transcriptase polymerase chain reactions (using commercial RNA) and examined the resultant complementary DNA through gel electrophoresis. I then proceeded to isolate and purify whole RNA from actual human monocytes and THP-1 cells using several published methods, and examined gene expression on the RNA itself. I compared the two RT-PCR methods and concluded that a double step RT-PCR is superior to the single step method. I also compared the various techniques of RNA isolation by examining the yield and purity of the resultant RNA. Finally, I studied the level of cellular IL-8 and IL-1 gene expression, two genes involved in the human immune response, which can serve as a baseline for future genetic comparison with LPS-exposed cells. Based on the results, I have determined which conditions and procedures are optimal for RNA isolation, RT-PCR, and RNA yield assessment. The overall goal of my research is to develop a flow-through system of RNA analysis, whereby blood samples can be collected and analyzed for disease prior to the onset of symptoms. The Pathomics group hopes to automate this process by removing the human labor factor, thereby decreasing the procedure's cost and increasing its availability to the general population. Eventually, our aim is to have an autonomous diagnostic system based on RNA analysis that would

  15. M8L12 cubic cages with all facial Δ or facial Λ configuration: effects of surface anions on the occupancy of the cage and anion exchange.

    PubMed

    Yang, Jing; Chang, Xiao-Yong; Sham, Kiu-Chor; Yiu, Shek-Man; Kwong, Hoi-Lun; Che, Chi-Ming

    2016-05-01

    M8L12 cubic cages (M = Mn(II), Zn(II) or Cd(II)), with all eight metal ions having all facial Δ or facial Λ configurations and having an encapsulated anion, were prepared by the self-assembly of m-xylene-bridged imidazolyl-imine ligands and MX2 (X = PF6(-), SbF6(-), TfO(-)) salts; the encapsulated anion exchange with different anions (SbF6(-), Tf2N(-), NO3(-), TsO(-)) was studied and the results with NO3(-) and TsO(-) indicate that anions on the cage surfaces affect the encapsulated anion exchange and the occupancy of the cage.

  16. Effect of magnesium/calcium ratios in solutions treated by electrodialysis: morphological characterization and identification of anion-exchange membrane fouling.

    PubMed

    Casademont, Christophe; Pourcelly, Gérald; Bazinet, Laurent

    2008-06-01

    The present study aimed the characterization of the fouling formed on anion-exchange membrane during electrodialysis treatment of model salt solutions at different Mg/Ca ratio (0, 1/20, 1/10, 1/5 and 2/5). The membrane fouling was characterized by membrane parameters (membrane thickness and electrical conductivity) and identified by membrane surface analysis (elemental analysis and X-ray diffraction). The mineral deposit was identified as Ca(OH)2 when no magnesium was present in the model salt. As soon as magnesium was present in the model salt solution for neutral pH((concentrate)) conditions a mix between CaCO3 and Ca(OH)2 was formed. This study is the first one to report the influence of magnesium in solution on the formation of CaCO3 fouling at the interface of anion-exchange membrane during electrodialysis.

  17. Kinetics and mechanism of exogenous anion exchange in FeFbpA-NTA: significance of periplasmic anion lability and anion binding activity of ferric binding protein A.

    PubMed

    Heymann, Jared J; Gabricević, Mario; Mietzner, Timothy A; Crumbliss, Alvin L

    2010-02-01

    The bacterial transferrin ferric binding protein A (FbpA) requires an exogenous anion to facilitate iron sequestration, and subsequently to shuttle the metal across the periplasm to the cytoplasmic membrane. In the diverse conditions of the periplasm, numerous anions are known to be present. Prior in vitro experiments have demonstrated the ability of multiple anions to fulfill the synergistic iron-binding requirement, and the identity of the bound anion has been shown to modulate important physicochemical properties of iron-bound FbpA (FeFbpA). Here we address the kinetics and mechanism of anion exchange for the FeFbpA-nitrilotriacetate (NTA) assembly with several biologically relevant anions (citrate, oxalate, phosphate, and pyrophosphate), with nonphysiologic NTA serving as a representative synergistic anion/chelator. The kinetic data are consistent with an anion-exchange process that occurs in multiple steps, dependent on the identity of both the entering anion and the leaving anion. The exchange mechanism may proceed either as a direct substitution or through an intermediate FeFbpA-X* assembly based on anion (X) identity. Our kinetic results further develop an understanding of exogenous anion lability in the periplasm, as well as address the final step of the iron-free FbpA (apo-FbpA)/Fe(3+) sequestration mechanism. Our results highlight the kinetic significance of the FbpA anion binding site, demonstrating a correlation between apo-FbpA/anion affinity and the FeFbpA rate of anion exchange, further supporting the requirement of an exogenous anion to complete tight sequestration of iron by FbpA, and developing a mechanism for anion exchange within FeFbpA that is dependent on the identity of both the entering anion and the leaving anion.

  18. Mechanism for binding site diversity on ankyrin. Comparison of binding sites on ankyrin for neurofascin and the Cl-/HCO3- anion exchanger.

    PubMed

    Michaely, P; Bennett, V

    1995-12-29

    Ankyrins are a family of spectrin-binding proteins that associate with at least seven distinct membrane proteins, including ion transporters and cell adhesion molecules. The membrane-binding domain of ankyrin is comprised of a tandem array of 24 ANK repeats organized into four 6-repeat folding domains. Tandem arrays of ANK repeats have been proposed to mediate protein interactions in a variety of proteins including factors involved in the regulation of transcription and the cell cycle. This report provides several new insights into the versatility of ANK repeats of ankyrin in protein recognition, using neurofascin and the Cl-/HCO3- anion exchanger as model ligands and ankyrinR as the prototypic ankyrin. Different combinations of ANK repeat domains from this ankyrin form two distinct, high affinity binding sites for neurofascin. One site requires both repeat domains 3 and 4. The other site involves both repeat domains 2 and 3, although domain 2 has significant activity alone. The sites appear to be independent with Kd values of 3 and 14 nM, respectively. Both the Cl-/HCO3- anion exchanger and neurofascin can interact simultaneously with repeat domains 3 and 4, because neurofascin is unable to displace binding of the anion exchanger cytoplasmic domain to domains 3 and 4, despite having a 3-5-fold higher affinity. These results demonstrate two levels of diversity in the binding sites on ankyrin: one resulting from different combinations of ANK repeat domains and another from different determinants within the same combination of repeat domains. One consequence of this diversity is that ankyrin can accommodate two neurofascin molecules as well as the anion exchanger through interactions mediated by ANK repeats. The ability of ankyrin to simultaneously associate with multiple types of membrane proteins is an unanticipated finding with implications for the assembly of integral membrane proteins into specialized regions of the plasma membrane.

  19. Anion-exchange high-performance liquid chromatography with post-column detection for the analysis of phytic acid and other inositol phosphates

    NASA Technical Reports Server (NTRS)

    Rounds, M. A.; Nielsen, S. S.; Mitchell, C. A. (Principal Investigator)

    1993-01-01

    The use of gradient anion-exchange HPLC, with a simple post-column detection system, is described for the separation of myo-inositol phosphates, including "phytic acid" (myo-inositol hexaphosphate). Hexa-, penta-, tetra-, tri- and diphosphate members of this homologous series are clearly resolved within 30 min. This method should facilitate analysis and quantitation of "phytic acid" and other inositol phosphates in plant, food, and soil samples.

  20. Anion-exchange high-performance liquid chromatography with post-column detection for the analysis of phytic acid and other inositol phosphates.

    PubMed

    Rounds, M A; Nielsen, S S

    1993-10-29

    The use of gradient anion-exchange HPLC, with a simple post-column detection system, is described for the separation of myo-inositol phosphates, including "phytic acid" (myo-inositol hexaphosphate). Hexa-, penta-, tetra-, tri- and diphosphate members of this homologous series are clearly resolved within 30 min. This method should facilitate analysis and quantitation of "phytic acid" and other inositol phosphates in plant, food, and soil samples.

  1. Experimental and theoretical study of anion-exchange preparative chromatography for neptunium: the first application to thorium(IV) and its equilibrium and kinetics.

    PubMed

    Yamamura, Tomoo; Miyakoshi, Takeshi; Shiokawa, Yoshinobu; Mitsugashira, Toshiaki

    2007-10-26

    In order to study equilibrium and kinetic parameters in anion-exchange chromatography for preparatory purpose, a quantitative model for nonlinear anion-exchange chromatography in porous media was constructed, by paying special attention to interstitial length along void structure (cm) distinguished from apparent length (cm*). Langmuir-type adsorption isotherm for thorium(IV), as a natural substitution for neptunium(IV), in 6 mol dm(-3) nitric acid to anion-exchanger MSA-1 (200-400 mesh) was investigated in batch-wise and chromatographic experiments. The equilibrium parameters determined by batch-wise experiments determined as k=2.4x10(2) mol(-1) dm3 s(-1) and s0=0.5 mol dm(-3) agrees very well with the values of k=222 mol(-1) dm3 s(-1) and s0=0.5 mol dm(-3) derived from fitting by the numerical calculation. Kinetic parameters of ks and D affect band profile similarly, thereby maximum value of each parameter was evaluated as ks=1.3 mol(-1) dm3 s(-1) and D=9x10(-4) cm2 s(-1) by the numerical calculations.

  2. Fast Anion-Exchange in Highly Luminescent Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I)

    PubMed Central

    2015-01-01

    Postsynthetic chemical transformations of colloidal nanocrystals, such as ion-exchange reactions, provide an avenue to compositional fine-tuning or to otherwise inaccessible materials and morphologies. While cation-exchange is facile and commonplace, anion-exchange reactions have not received substantial deployment. Here we report fast, low-temperature, deliberately partial, or complete anion-exchange in highly luminescent semiconductor nanocrystals of cesium lead halide perovskites (CsPbX3, X = Cl, Br, I). By adjusting the halide ratios in the colloidal nanocrystal solution, the bright photoluminescence can be tuned over the entire visible spectral region (410–700 nm) while maintaining high quantum yields of 20–80% and narrow emission line widths of 10–40 nm (from blue to red). Furthermore, fast internanocrystal anion-exchange is demonstrated, leading to uniform CsPb(Cl/Br)3 or CsPb(Br/I)3 compositions simply by mixing CsPbCl3, CsPbBr3, and CsPbI3 nanocrystals in appropriate ratios. PMID:26207728

  3. Fast Anion-Exchange in Highly Luminescent Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I).

    PubMed

    Nedelcu, Georgian; Protesescu, Loredana; Yakunin, Sergii; Bodnarchuk, Maryna I; Grotevent, Matthias J; Kovalenko, Maksym V

    2015-08-12

    Postsynthetic chemical transformations of colloidal nanocrystals, such as ion-exchange reactions, provide an avenue to compositional fine-tuning or to otherwise inaccessible materials and morphologies. While cation-exchange is facile and commonplace, anion-exchange reactions have not received substantial deployment. Here we report fast, low-temperature, deliberately partial, or complete anion-exchange in highly luminescent semiconductor nanocrystals of cesium lead halide perovskites (CsPbX3, X = Cl, Br, I). By adjusting the halide ratios in the colloidal nanocrystal solution, the bright photoluminescence can be tuned over the entire visible spectral region (410-700 nm) while maintaining high quantum yields of 20-80% and narrow emission line widths of 10-40 nm (from blue to red). Furthermore, fast internanocrystal anion-exchange is demonstrated, leading to uniform CsPb(Cl/Br)3 or CsPb(Br/I)3 compositions simply by mixing CsPbCl3, CsPbBr3, and CsPbI3 nanocrystals in appropriate ratios.

  4. Anion Exchange Behavior Of Ti, Zr, Hf, Nb And Ta As Homologues Of Rf And Db In Mixed HF--Acetone Solutions

    SciTech Connect

    Aksenov, N. V.; Bozhikov, G. A.; Starodub, G. Ya.; Dmitriev, S. N.; Filosofov, D. V.; Sun Jin, Jon; Radchenko, V. I.; Lebedev, N. A.; Novgorodov, A. F.

    2010-04-30

    We studied in detail the sorption behavior of Ti, Zr, Hf, Nb and Ta on AG 1 anion exchange resin in HF-acetone mixed solutions as a function of organic cosolvent and acid concentrations. Anion exchange behavior was found to be strongly acetone concentration dependent. The distribution coefficients of Ti, Zr, Hf and Nb increased and those of Ta decreased with increasing content of acetone in HF solutions. With increasing HF concentration anion exchange equilibrium analysis indicated the formation of fluoride complexes of group 4 elements with charge-3 and Ta---2. For Nb the slope of-2 increased up to-5. Optimal conditions for separation of the elements using AIX chromatography were found. Group 4 elements formed MF{sub 7}{sup 3-} (M = Ti, Zr, Hf) complexes whose sorption decreased Ti>Hf>Zr in reverse order of complex stability. This fact is of particular interest for studying ion exchange behavior of Rf compared to Ti. The advantages of studying chemical properties of Rf and Db in aqueous HF solutions mixed with organic solvents are briefly discussed.

  5. Tracking the Superefficient Anion Exchange of a Dynamic Porous Material Constructed by Ag(I) Nitrate and Tripyridyltriazole via Multistep Single-Crystal to Single-Crystal Transformations.

    PubMed

    Li, Cheng-Peng; Liu, Bo-Lan; Wang, Lei; Liu, Yue; Tian, Jia-Yue; Liu, Chun-Sen; Du, Miao

    2017-03-01

    To avoid the instability and inefficiency for anion-exchange resins and layered double-hydroxides materials, we present herein a flexible coordination network [Ag(L(243))](NO3)(H2O)(CH3CN) (L(243) = 3-(2-pyridyl)-4-(4-pyridyl)-5-(3-pyridyl)-1,2,4-triazole) with superefficient trapping capacity for permanganate, as a group-7 oxoanion model for radiotoxic pertechnetate pollutant. Furthermore, a high-throughput screening strategy has been developed based on concentration-gradient design principle to ascertain the process and mechanism for anion exchange. Significantly, a series of intermediates can be successfully isolated as the qualified crystals for single-crystal X-ray diffraction. The result evidently indicates that such a dynamic material will show remarkable breathing effect of the three-dimensional host framework upon anion exchange, which mostly facilitates the anion trapping process. This established methodology will provide a general strategy to discover the internal secrets of complicated solid-state reactions in crystals at the molecular level.

  6. The separation of platinum, palladium and gold from silicate rocks by the anion exchange separation of chloro complexes after a sodium peroxide fusion: an investigation of low recoveries.

    PubMed

    Enzweiler, J; Potts, P J

    1995-10-01

    A series of experiments was undertaken to measure the recovery efficiency of platinum, palladium and gold from silicate rocks using a sodium peroxide fusion followed by anion exchange separation of the analytes as chloro complexes. Results obtained by graphite furnace atomic absorption spectrometric analysis of standard solutions prepared in dilute HCl or HCl-acidified sodium peroxide solution showed that recoveries were near quantitative. However, when standard solutions were added to an alkaline sodium peroxide solution, which was then acidified, low results were obtained for platinum and gold (46% and 76% respectively). Low and variable results were also obtained when standard solutions were added to a peridotite sample that had been dissolved by the state procedure, and in the analysis of the South African Bureau of Standards certified reference material, SARM 7. Various experiments were undertaken to investigate these low recoveries, but the reason proposed here is the formation of hydroxychloro compounds in alkaline solution which are not, on acidification with HCl, converted quantitatively to the chloro complex necessary for quantitative anion exchange separation. It is concluded that a sodium peroxide fusion followed by an anion-exchange separation does not appear to form the basis of a successful technique for the determination of platinum, palladium and gold in silicate rocks.

  7. Prefractionation of intact proteins by reversed-phase and anion-exchange chromatography for the differential proteomic analysis of Saccharomyces cerevisiae.

    PubMed

    Stobaugh, Jordan T; Fague, Kaitlin M; Jorgenson, James W

    2013-02-01

    The need for multidimensional separations for bottom-up proteomic analyses has been well demonstrated by many over the past decade. The vast majority of reported approaches has focused primarily on improving the separation once the sample has already been digested. The work presented in this study shows an improvement in multidimensional approaches by prefractionation of intact proteins prior to digestion and separation of the peptides. Two modes of intact protein separation were compared, anion-exchange and reversed-phase, to assess the utility of each mode for the purpose of fractionation. Each of the samples was then enzymatically digested and analyzed by RP-UPLC-MS(E). To assess the validity of each approach, baker's yeast (Saccharomyces cerevisiae) was grown on two different carbon sources, glycerol and dextrose. More proteins were identified by the reversed-phase prefractionation approach (546) than were found by the anion-exchange method (262). As a result, there was much greater coverage of the metabolic pathways of interest for the reversed-phase method than for the anion-exchange method.

  8. Production and partial purification of Salmonella enterotoxin.

    PubMed Central

    Sedlock, D M; Koupal, L R; Deibel, R H

    1978-01-01

    By using a strain of Salmonella typhimurium, we detected the presence of an enterotoxin, as determined by the rabbit ileal loop assay, in various complex and defined media. The enterotoxin was concentrated by ultrafiltration of culture supernatant fluids and eluted in and adjacent to the void volume of a Sephadex G-100 column. This suggested that the enterotoxic factor was of a relatively high molecular weight, and additional evidence indicated it was heterogeneous in size. Further chromatography, using a diethylaminoethyl-cellulose anion exchanger, facilitated at least a 50-fold purification of the Salmonella enterotoxin. PMID:352941

  9. Determination of propofol glucuronide from hair sample by using mixed mode anion exchange cartridge and liquid chromatography tandem mass spectrometry.

    PubMed

    Kwak, Jae-Hwan; Kim, Hye Kyung; Choe, Sanggil; In, Sangwhan; Pyo, Jae Sung

    2016-03-15

    The main objective of this study was to develop and validate a simpler and less time consuming analytical method for determination of propofol glucuronide from hair sample, by using mixed mode anion exchange cartridge and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The study uses propofol glucuronide, a major metabolite of propofol, as a marker for propofol abuse. The hair sample was digested in sodium hydroxide solution and loaded in mixed-mode anion cartridge for solid phase extraction. Water and ethyl acetate were used as washing solvents to remove interfering substances from the hair sample. Consequently, 2% formic acid in ethyl acetate was employed to elute propofol glucuronide from the sorbent of mixed-mode anion cartridge, and analyzed by LC-MS/MS. The method validation parameters such as selectivity, specificity, LOD, LLOQ, accuracy, precision, recovery, and matrix effect were also tested. The linearity of calibration curves showed good correlation, with correlation coefficient 0.998. The LOD and LLOQ of the propofol glucuronide were 0.2 pg/mg and 0.5 pg/mg, respectively. The intra and inter-day precision and accuracy were acceptable within 15%. The mean values of recovery and matrix effect were in the range of 91.7-98.7% and 87.5-90.3%, respectively, signifying that the sample preparation, washing and extraction procedure were efficient, and there was low significant hair matrix effect for the extraction of propofol glucuronide from hair sample on the mixed mode anion cartridge. To evaluate the suitability of method, the hair of propofol administered rat was successfully analyzed with this method.

  10. A new anionic exchange stir bar sorptive extraction coating based on monolithic material for the extraction of inorganic anion.

    PubMed

    Huang, Xiaojia; Lin, Jianbing; Yuan, Dongxing

    2010-07-23

    A novel anionic exchange stir bar sorptive extraction (SBSE) coating based on poly(2-(methacryloyloxy)ethyltrimethylammonium chloride-co-divinylbenzene) monolithic material for the extraction of inorganic anion was prepared. The effect of preparation conditions such as ratio of functional monomer to cross-linker, content of porogenic solvent on the extraction efficiencies were investigated in detailed. The monolithic material was characterized by elemental analysis, scanning electron microscopy and infrared spectroscopy. In order to investigate the extraction capacity of the new coating for inorganic anion, the new SBSE was combined with ionic chromatography with conductivity detection, Br-, NO3-, PO4(3-) and SO4(2-) were selected as detected solutes. Several extractive parameters, including pH value and ionic strength in sample matrix, desorption solvent, extraction and desorption time were optimized. The results showed that strongly ionic strength did not favor the extraction of anlaytes. Under the optimum experimental conditions, low detection limits (S/N=3) and quantification limits (S/N=10) of the proposed method for the target anions were achieved within the range of 0.92-2.62 and 3.03-9.25 microg/L, respectively. The method also showed good linearity, simplicity, practicality and low cost for the extraction inorganic anions. Finally, the proposed method was successfully used to detect the two different trademarks of commercial purified water with satisfactory recovery in the range of 70.0-92.6%. To the best of our knowledge, this is the first to use SBSE to enrich inorganic anions.

  11. Polyethylenimine modified poly(ethylene terephthalate) capillary channeled-polymer fibers for anion exchange chromatography of proteins.

    PubMed

    Jiang, Liuwei; Jin, Yi; Marcus, R Kenneth

    2015-09-04

    Native poly(ethylene terephthalate) (PET) capillary-channeled polymer (C-CP) fibers have been previously studied as stationary phases for reversed phase and affinity protein separations. In this study, surface modified PET C-CP fibers were evaluated for the anion exchange separation of proteins. The native PET C-CP fibers were aminated using polyethylenimine (PEI) followed by a 1,4-butanediol diglycidyl ether (BUDGE) cross-linking step. Subsequent PEI/BUDGE treatments can be employed to further develop the polyamine layer on the fiber surfaces. The PEI densities of the modified fibers were quantified through the ninhydrin reaction, yielding values of 0.43-0.89μmolg(-1). The surface modification impact on column permeability was found to be 0.66×10(-11) to 1.33×10(-11)m(2), depending on the modification time and conditions. The dynamic binding capacities of the modified fiber media were determined to be 1.99-8.54mgmL(-1) bed volume, at linear velocities of 88-438cmmin(-1) using bovine serum albumin as the model protein. It was found that increasing the mobile phase linear velocity (up to 438cmmin(-1)) had no effect on the separation quality for a synthetic protein mixture, reflecting the lack of van Deemter C-term effects for the C-CP fiber phase. The low-cost, easy modification method and the capability of fast protein separation illustrate great potential in the use of PEI/BUDGE-modified PET C-CP fibers for high-throughput protein separation and downstream processing.

  12. Molecular mechanisms of epithelial cell-specific expression and regulation of the human anion exchanger (pendrin) gene.

    PubMed

    Adler, Lior; Efrati, Edna; Zelikovic, Israel

    2008-05-01

    Pendrin, a Cl(-)/anion exchanger encoded by the gene PDS, is highly expressed in the kidney, thyroid, and inner ear epithelia and is essential for bicarbonate secretion, iodide accumulation, and endolymph ion balance, respectively. This study aimed to define promoter regulatory elements essential for renal, thyroid, and inner ear epithelial cell-specific expression of human PDS (hPDS) and to explore the effect of ambient pH and aldosterone on hPDS promoter activity. Endogenous pendrin mRNA and protein were detected in renal HEK293, thyroid LA2, and inner ear VOT36 epithelial cell lines, but not in the fibroblast cell line, NIH3T3. A 4.2-kb hPDS 5'-flanking DNA sequence and consecutive 5'-deletion products were cloned into luciferase reporter vectors and transiently transfected into the above cell lines. Distinct differences in expression/activity of deduced positive/negative regulatory elements within the hPDS promoter between HEK293, LA2, and VOT36 cells were demonstrated, with only basal activity in NIH3T3 cells. Acidic pH (7.0-7.1) decreased and alkaline pH (7.6-7.7) increased hPDS promoter activity in transfected HEK293 and VOT36, but not in LA2 cells. Aldosterone (10(-8) M) reduced hPDS promoter activity in HEK293 but had no effect in LA2 and VOT36 cells. These pH and aldosterone-induced effects on the hPDS promoter occurred within 96-bp and 89-bp regions, respectively, which likely contain distinct response elements to these modulators. Acidic pH and aldosterone decreased, and alkaline pH increased, endogenous pendrin mRNA level in HEK293 cells. In conclusion, pendrin-mediated HCO3(-) secretion in the renal tubule and anion transport in the endolymph may be regulated transcriptionally by systemic pH and aldosterone.

  13. Study on adsorption properties of QCS/PS-G8-2-8 anion exchange membrane for Rhodamine B

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Wang, Jilin; Wang, Lulu; Feng, Ruijiang; Zhang, Fan

    2015-06-01

    A series of novel anion exchange composite membrane (QCS/PS-G8-2-8) were synthesized based on the quaternized chitosan (QCS, DQ = 89.20 (±3.50)%) blended with block polymer of polystyrene (PS) and G8-2-8 (maleic acid diethyl brace base pairs [octyl dimethyl chloride/ammonium bromide]). Then the QCS was cross-linked by glutaraldehyde (GA). The parameters including adsorption time (t), pH, and initial concentration of Rhodamine B (C0), temperature (T), the mass fraction of G8-2-8 and GA (WGA) on the adsorption were investigated to determine the optimum condition for the removal of RB. The kinetic and thermodynamic properties of the adsorption process were also discussed. The optimum adsorption condition was that the adsorption time was 100 min, pH was 4, the initial concentration of RB was 100 mg L-1, the mass fraction of G8-2-8 was 5.0 wt%, the mass fraction of GA was 2.0 wt%, the temperature was 40 °C. Thus, RB optimum adsorption capacity (q) of the composite membrane QCS/PS-G8-2-8 (5.0%) (G8-2-8 mass content (wt.%) was 5.0%) was 17.04 mg g-1. The adsorption isotherm of the RB on the composite membrane can be well fitted with the Temkin equation. The adsorption kinetics can be well described by the pseudo-second-order kinetics model. The values of ΔG, ΔH and ΔS indicated that the adsorption of RB onto QCS/PS-G8-2-8 was spontaneous and exothermic.

  14. Use of niflumic acid to determine the nature of the asymmetry of the human erythrocyte anion exchange system

    PubMed Central

    1984-01-01

    Niflumic acid is a noncompetitive inhibitor of chloride exchange, which binds to a site different from the transport or modifier sites. When the internal Cl- concentration is raised, at constant extracellular Cl- , the inhibitory potency of niflumic acid increases. This effect cannot be attributed to changes in membrane potential, but rather it suggests that niflumic acid binds to the anion exchange protein band 3 only when the transport site faces outward. When the chloride gradient is reversed, with Clo greater than Cli , the inhibitory potency of niflumic acid decreases greatly, which indicates that the affinity of niflumic acid for band 3 with the transport site facing inward is almost 50 times less than when the transport site faces outward. Experiments in which Cli = Clo show no significant change in the inhibition by niflumic acid when Cl- is lowered from 150 to 10 mM. These data suggest that the intrinsic dissociation constants for Cl- at the two sides of the membrane are nearly equal. Thus, the chloride- loaded transport sites have an asymmetric orientation like that of the unloaded transport sites, with approximately 15 times more sites facing the inside than the outside. The asymmetry reflects an approximately 1.5 kcal/mol free energy difference between the inward-facing and outward-facing chloride-loaded forms of band 3. High concentrations of chloride (with Cli = Clo), which partially saturate the modifier site, have no effect on niflumic acid inhibition, which indicates that chloride binds equally well to the modifier site regardless of the orientation of the transport site. PMID:6736917

  15. Chloride transport in red blood cells of lamprey Lampetra fluviatilis: evidence for a novel anion-exchange system.

    PubMed

    Bogdanova AYu; Sherstobitov, A O; Gusev, G P

    1998-03-01

    The existence of a furosemide-sensitive Cl- transport pathway activated by external Ca2+ and Mg2+ has been demonstrated previously in studies of Cl- influx across the lamprey erythrocyte membrane. The aim of the present study was to characterize further specific Cl- transport pathways, especially those involved in Cl- efflux, in the red blood cell membrane of Lampetra fluviatilis. Cl- efflux was inhibited by 0.05 mmol l-1 dihydroindenyloxyalkanoic acid (DIOA) (81%), 1 mmol l-1 furosemide (76%) and 0.1 mmol l-1 niflumic acid (54%). Bumetanide (100 mumol l-1) and DIDS (100 mumol l-1) had no effect effect on Cl- efflux. Substitution of external Cl- by gluconate, but not by NO3-, led to a gradual decline of Cl- efflux. In addition, the removal of external Ca2+ resulted in a significant reduction in the rate of Cl- efflux. Membrane depolarization caused by increasing external K+ concentration or by inhibiting K+ channels with 1 mmol l-1 Ba2+ did not affect Cl- efflux. The furosemide-sensitive component of Cl- influx was a saturable function of external [Cl-] with an apparent K(m) of approximately 92 mmol l-1 and Vmax of approximately 17.8 mmol l-1 cells-1 h-1. Furosemide did not affect intracellular Cl- concentration (57.6 +/- 5.2 mmol l-1 cell water), measured using an ion-selective Cl- electrode, showing that a furosemide-sensitive pathway is not involved in net Cl- movement. A gradual fall (from 28.1 +/- 1.4 to 15.0 +/- 1.3 mmol l-1 cells-1 h-1) in unidirectional Cl- influx with time was observed within 3 h of cell preincubation in the standard physiological medium. These data provide evidence for the existence for an electroneutral furosemide-sensitive anion-exchange pathway in the lamprey erythrocyte membrane that accepts chloride and nitrate, but not bicarbonate or bromide.

  16. Use of niflumic acid to determine the nature of the asymmetry of the human erythrocyte anion exchange system.

    PubMed

    Knauf, P A; Mann, N A

    1984-05-01

    Niflumic acid is a noncompetitive inhibitor of chloride exchange, which binds to a site different from the transport or modifier sites. When the internal Cl- concentration is raised, at constant extracellular Cl-, the inhibitory potency of niflumic acid increases. This effect cannot be attributed to changes in membrane potential, but rather it suggests that niflumic acid binds to the anion exchange protein band 3 only when the transport site faces outward. When the chloride gradient is reversed, with Clo greater than Cli , the inhibitory potency of niflumic acid decreases greatly, which indicates that the affinity of niflumic acid for band 3 with the transport site facing inward is almost 50 times less than when the transport site faces outward. Experiments in which Cli = Clo show no significant change in the inhibition by niflumic acid when Cl- is lowered from 150 to 10 mM. These data suggest that the intrinsic dissociation constants for Cl- at the two sides of the membrane are nearly equal. Thus, the chloride-loaded transport sites have an asymmetric orientation like that of the unloaded transport sites, with approximately 15 times more sites facing the inside than the outside. The asymmetry reflects an approximately 1.5 kcal/mol free energy difference between the inward-facing and outward-facing chloride-loaded forms of band 3. High concentrations of chloride (with Cli = Clo), which partially saturate the modifier site, have no effect on niflumic acid inhibition, which indicates that chloride binds equally well to the modifier site regardless of the orientation of the transport site.

  17. Assessing Gibberellins Oxidase Activity by Anion Exchange/Hydrophobic Polymer Monolithic Capillary Liquid Chromatography-Mass Spectrometry

    PubMed Central

    Liu, Jiu-Feng; Wu, Yan; Feng, Yu-Qi; Yuan, Bi-Feng

    2013-01-01

    Bioactive gibberellins (GAs) play a key regulatory role in plant growth and development. In the biosynthesis of GAs, GA3-oxidase catalyzes the final step to produce bioactive GAs. Thus, the evaluation of GA3-oxidase activity is critical for elucidating the regulation mechanism of plant growth controlled by GAs. However, assessing catalytic activity of endogenous GA3-oxidase remains challenging. In the current study, we developed a capillary liquid chromatography – mass spectrometry (cLC-MS) method for the sensitive assay of in-vitro recombinant or endogenous GA3-oxidase by analyzing the catalytic substrates and products of GA3-oxidase (GA1, GA4, GA9, GA20). An anion exchange/hydrophobic poly([2-(methacryloyloxy)ethyl]trimethylammonium-co-divinylbenzene-co-ethylene glycol dimethacrylate)(META-co-DVB-co-EDMA) monolithic column was successfully prepared for the separation of all target GAs. The limits of detection (LODs, Signal/Noise = 3) of GAs were in the range of 0.62–0.90 fmol. We determined the kinetic parameters (Km) of recombinant GA3-oxidase in Escherichia coli (E. coli) cell lysates, which is consistent with previous reports. Furthermore, by using isotope labeled substrates, we successfully evaluated the activity of endogenous GA3-oxidase that converts GA9 to GA4 in four types of plant samples, which is, to the best of our knowledge, the first report for the quantification of the activity of endogenous GA3-oxidase in plant. Taken together, the method developed here provides a good solution for the evaluation of endogenous GA3-oxidase activity in plant, which may promote the in-depth study of the growth regulation mechanism governed by GAs in plant physiology. PMID:23922762

  18. Formation of Semimetallic Cobalt Telluride Nanotube Film via Anion Exchange Tellurization Strategy in Aqueous Solution for Electrocatalytic Applications.

    PubMed

    Patil, Supriya A; Kim, Eun-Kyung; Shrestha, Nabeen K; Chang, Jinho; Lee, Joong Kee; Han, Sung-Hwan

    2015-11-25

    Metal telluride nanostructures have demonstrated several potential applications particularly in harvesting and storing green energy. Metal tellurides are synthesized by tellurization process performed basically at high temperature in reducing gas atmosphere, which makes the process expensive and complicated. The development of a facile and economical process for desirable metal telluride nanostructures without complicated manipulation is still a challenge. In an effort to develop an alternative strategy of tellurization, herein we report a thin film formation of self-standing cobalt telluride nanotubes on various conducting and nonconducting substrates using a simple binder-free synthetic strategy based on anion exchange transformation from a thin film of cobalt hydroxycarbonate nanostructures in aqueous solution at room temperature. The nanostructured films before and after ion exchange transformation reaction are characterized using field emission scanning electron microscope, energy dispersive X-ray analyzer, X-ray photoelectron spectroscopy, thin film X-ray diffraction technique, high resolution transmission electron microscope, and selected area electron diffraction analysis technique. After the ion exchange transformation of nanostructures, the film shows conversion from insulator to highly electrical conductive semimetallic characteristic. When used as a counter electrode in I3(-)/I(-) redox electrolyte based dye-sensitized solar cells, the telluride film exhibits an electrocatalytic reduction activity for I3(-) with a demonstration of solar-light to electrical power conversion efficiency of 8.10%, which is highly competitive to the efficiency of 8.20% exhibited by a benchmarked Pt-film counter electrode. On the other hand, the telluride film electrode also demonstrates electrocatalytic activity for oxygen evolution reaction from oxidation of water.

  19. Sorption and desorption of perchlorate and U(VI) by strong-base anion-exchange resins.

    PubMed

    Gu, Baohua; Ku, Yee-Kyoung; Brown, Gilbert M

    2005-02-01

    This study investigated the sorption affinity and capacity of six strong-base anion-exchange (SBA) resins for both uranium [U(VI)] and perchlorate (ClO4-) in simulated groundwater containing varying concentrations of sulfate (SO4(2-)). Additionally, desorption of U(VI) from spent resins was studied to separate U(VI) from resins with sorbed ClO4- for waste segregation and minimization. Results indicate that all SBA resins investigated in this study strongly sorb U(VI). The gel-type polyacrylic resin (Purolite A850) showed the highest sorption affinity and capacityfor U(VI) butwasthe least effective in sorbing ClO4-. The presence of SO4(2-) had little impact on the sorption of U(VI) but significantly affected the sorption of ClO4-, particularly on monofunctional SBA resins. A dilute acid wash was found to be effective in desorbing U(VI) but ineffective in desorbing ClO4- from bifunctional resins (Purolite A530E and WBR109). A single wash removed approximately 75% of sorbed U(VI) but only approximately 0.1% of sorbed ClO4- from the bifunctional resins. On the other hand, only 21.4% of sorbed U(VI) but approximately 34% of sorbed ClO4- was desorbed from the Purolite A850 resin. This study concludes that bifunctional resins could be used effectively to treatwater contaminated with ClO4- and traces of U(VI), and dilute acid washes could minimize hazardous wastes by separating sorbed U(VI) from ClO4- prior to the regeneration of the spent resin loaded with ClO4-.

  20. The noncompetitive inhibitor WW781 senses changes in erythrocyte anion exchanger (AE1) transport site conformation and substrate binding.

    PubMed

    Knauf, P A; Raha, N M; Spinelli, L J

    2000-02-01

    WW781 binds reversibly to red blood cell AE1 and inhibits anion exchange by a two-step mechanism, in which an initial complex (complex 1) is rapidly formed, and then there is a slower equilibration to form a second complex (complex 2) with a lower free energy. According to the ping-pong kinetic model, AE1 can exist in forms with the anion transport site facing either inward or outward, and the transition between these forms is greatly facilitated by binding of a transportable substrate such as Cl(-). Both the rapid initial binding of WW781 and the formation of complex 2 are strongly affected by the conformation of AE1, such that the forms with the transport site facing outward have higher affinity than those with the transport site facing inward. In addition, binding of Cl(-) seems to raise the free energy of complex 2 relative to complex 1, thereby reducing the equilibrium binding affinity, but Cl(-) does not compete directly with WW781. The WW781 binding site, therefore, reveals a part of the AE1 structure that is sensitive to Cl(-) binding and to transport site orientation, in addition to the disulfonic stilbene binding site. The relationship of the inhibitory potency of WW781 under different conditions to the affinities for the different forms of AE1 provides information on the possible asymmetric distributions of unloaded and Cl(-)-loaded transport sites that are consistent with the ping-pong model, and supports the conclusion from flux and nuclear magnetic resonance data that both the unloaded and Cl(-)-loaded sites are very asymmetrically distributed, with far more sites facing the cytoplasm than the outside medium. This asymmetry, together with the ability of WW781 to recruit toward the forms with outward-facing sites, implies that WW781 may be useful for changing the conformation of AE1 in studies of structure-function relationships.

  1. Novel quaternized poly(arylene ether sulfone)/Nano-ZrO₂ composite anion exchange membranes for alkaline fuel cells.

    PubMed

    Li, Xiuhua; Yu, Yingfeng; Meng, Yuezhong

    2013-02-01

    A series of composite anion exchange membranes based on novel quaternized poly(arylene ether sulfone)/nanozirconia (QPAES/nano-ZrO₂) composites are prepared using a solution casting method. The QPAES/nano-ZrO₂ composite membranes are characterized by FTIR, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDX). The ion exchange capacity (IEC), water uptake, swelling ratio, hydroxide ion conductivity, mechanical properties, thermal stability, and chemical stability of the composite membranes are measured to evaluate their applicability in fuel cells. The introduction of nano-ZrO₂ induces the crystallization of the matrix and enhances the IEC of the composite membranes. The modification with nano-ZrO₂ improves water uptake, dimension stability, hydroxide ion conductivity, mechanical properties, and thermal and chemical stabilities of the composite membranes. The QPAES/nano-ZrO₂ composite membranes show hydroxide ion conductivities over 25.7 mS cm⁻¹ at a temperature above 60 °C. Especially, the QPAES/nano-ZrO₂ composite membranes with the nano-ZrO₂ content above 7.5% display hydroxide ion conductivities over 41.4 mS cm⁻¹ at 80 °C. The E(a) values of the QPAES/nano-ZrO₂ composite membranes with the nano-ZrO₂ content above 5% are lower than 11.05 kJ mol⁻¹. The QPAES/7.5% nano-ZrO₂ composite membrane displays the lowest E(a) value and the best comprehensive properties and constitutes a good potential candidate for alkaline fuel cells.

  2. Raman spectroscopic study of the aging and nitration of actinide processing anion-exchange resins in concentrated nitric acid

    SciTech Connect

    Buscher, C. T.; Donohoe, R. J.; Mecklenburg, S. L.; Berg, J. M.; Tait, C. D.; Morris, D. E. [Chemical Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545

    1999-08-01

    Degradation of two types of anion exchange resins, Dowex 11 and Reillex HPQ, from the action of concentrated nitric acid (4 to 12 M) and radiolysis [from depleted uranium as UO{sub 2}{sup 2+} nitrate species and {sup 239}Pu as Pu(IV) nitrate species] was followed as a function of time with Raman vibrational spectroscopy. Elevated temperatures ({approx}50 degree sign C) were used in the absence of actinide metal loading to simulate longer exposures of the resin to a HNO{sub 3} process stream and waste storage conditions. In the absence of actinide loading, only minor changes in the Dowex resin at acid concentrations {<=}10 M were observed, while at 12 M acid concentration, the emergence of a Raman peak at 1345 cm-1 indicates the addition of nitro functional groups to the resin. Similar studies with the Reillex resin show it to be more resistant to nitric acid attack at all acid concentrations. Incorporation of weakly radioactive depleted uranium as the UO{sub 2}{sup 2+} nitrate species to the ion-exchange sites of Dowex 11 under differing nitric acid concentrations (6 to 12 M) at room temperature showed no Raman evidence of resin degradation or nitration, even after several hundred days of contact. In contrast, Raman spectra for Dowex 11 in the presence of {sup 239}Pu as Pu(IV) nitrate species reveal numerous changes indicating resin alterations, including a new mode at 1345 cm-1 consistent with a Pu(IV)-nitrate catalyzed addition of nitro groups to the resin backbone. (c) 2000 Society for Applied Spectroscopy.

  3. Selective colorimetric determination of TNT partitioned between an alkaline solution and a strongly basic Dowex 1-X8 anion exchanger.

    PubMed

    Uzer, Ayşem; Erçağ, Erol; Apak, Reşat

    2008-01-30

    The Meisenheimer anions formed from TNT in KOH solutions in alcohol or acetone were used in screening tests for TNT among possible nitro-explosives. The same reaction was used for the spectrophotometric assay of TNT in soil by CRREL (Cold Regions Research & Engineering Laboratory of the U.S. Army) method, also known as Jenkins' method, but the color stability was too dependent on the solution composition and the water tolerance was low, necessitating complete drying of soil samples (which may cause partial analyte decomposition) prior to analysis. This study reports the development of a colorimetric method based on the solid phase extraction (SPE) of the Meisenheimer anion formed from TNT and aqueous NaOH into a strongly basic anion exchange resin Dowex 1-X8 (OH(-) form). The orange-red color that developed both in the solid resin and solution phases was persistent for at least 1h. The resin was let to swell in alcohol, washed first with 1M aqueous NaOH, and then with H(2)O before use. To 5 mL of 4-400 ppm TNT solutions in 1:1 (v/v) acetone-water, 0.5 mL of 5% NaOH was added, diluted to 50 mL with 1:1 acetone-water, and the resulting solutions (containing the orange-red Meisenheimer anion of TNT) were agitated at room temperature with 0.9 g resin for < or =50 min. TNT exhibited a reasonably constant distribution coefficient between the resin and aqueous phases. The absorbance of the filtered solutions was measured against a reagent blank at 500nm. The TNT-loaded resins were regenerated with 1M HCl containing sodium sulfite. The calibration line of filtrate absorbance versus analytical concentration was linear over two orders of magnitude between 0.4 and 40 ppm TNT in final solution. Unlike Jenkins' method, the method was tolerant to 100-fold (by mass) of common soil anions like sulfate, nitrate, and chloride. The basic advantages of the developed colorimetric method over the similar CRREL/Jenkins' method may be summarized as color stability, water and common ion

  4. Carbon nanotube supported PdAg nanoparticles for electrocatalytic oxidation of glycerol in anion exchange membrane fuel cells

    DOE PAGES

    Benipal, Neeva; Qi, Ji; Liu, Qi; ...

    2017-03-10

    Electro-oxidation of alcohol is the key reaction occurring at the anode of a direct alcohol fuel cell (DAFC), in which both reaction kinetics (rate) and selectivity (to deep oxidation products) need improvement to obtain higher power density and fuel utilization for a more efficient DAFC. We recently found that a PdAg bimetallic nanoparticle catalyst is more efficient than Pd for alcohol oxidation: Pd can facilitate deprotonation of alcohol in a base electrolyte, while Ag can promote intermediate aldehyde oxidation and cleavage of C-single bondC bond of C3 species to C2 species. Furthermore, a combination of the two active sites (Pdmore » and Ag) with two different functions, can simultaneously improve the reaction rates and deeper oxidation products of alcohols. In this continuing work, Pd, Ag mono, and bimetallic nanoparticles supported on carbon nanotubes (Ag/CNT, Pd/CNT, Pd1Ag1/CNT, and Pd1Ag3/CNT) were prepared using an aqueous-phase reduction method; they served as working catalysts for studying electrocatalytic oxidation of glycerol in an anion-exchange membrane-based direct glycerol fuel cell. Combined XRD, TEM, and HAADF-STEM analyses performed to fully characterize as-prepared catalysts suggested that they have small particle sizes: 2.0 nm for Pd/CNT, 2.3 nm for PdAg/CNT, 2.4 nm for PdAg3/CNT, and 13.9 nm for Ag/CNT. XPS further shows that alloying with Ag results in more metal state Pd presented on the surface, and this may be related to their higher direct glycerol fuel cell (DGFC) performances. Single DGFC performance and product analysis results show that PdAg bimetallic nanoparticles can not only improve the glycerol reaction rate so that higher power output can be achieved, but also facilitate deep oxidation of glycerol so that a higher faradaic efficiency and fuel utilization can be achieved along with optimal reaction conditions (increased base-to-fuel ratio). Half-cell electrocatalytic activity measurement and single fuel cell product analysis

  5. Semi-Automated Hydrophobic Interaction Chromatography Column Scouting Used in the Two-Step Purification of Recombinant Green Fluorescent Protein

    PubMed Central

    Murphy, Patrick J. M.

    2014-01-01

    Background Hydrophobic interaction chromatography (HIC) most commonly requires experimental determination (i.e., scouting) in order to select an optimal chromatographic medium for purifying a given target protein. Neither a two-step purification of untagged green fluorescent protein (GFP) from crude bacterial lysate using sequential HIC and size exclusion chromatography (SEC), nor HIC column scouting elution profiles of GFP, have been previously reported. Methods and Results Bacterial lysate expressing recombinant GFP was sequentially adsorbed to commercially available HIC columns containing butyl, octyl, and phenyl-based HIC ligands coupled to matrices of varying bead size. The lysate was fractionated using a linear ammonium phosphate salt gradient at constant pH. Collected HIC eluate fractions containing retained GFP were then pooled and further purified using high-resolution preparative SEC. Significant differences in presumptive GFP elution profiles were observed using in-line absorption spectrophotometry (A395) and post-run fluorimetry. SDS-PAGE and western blot demonstrated that fluorometric detection was the more accurate indicator of GFP elution in both HIC and SEC purification steps. Comparison of composite HIC column scouting data indicated that a phenyl ligand coupled to a 34 µm matrix produced the highest degree of target protein capture and separation. Conclusions Conducting two-step protein purification using the preferred HIC medium followed by SEC resulted in a final, concentrated product with >98% protein purity. In-line absorbance spectrophotometry was not as precise of an indicator of GFP elution as post-run fluorimetry. These findings demonstrate the importance of utilizing a combination of detection methods when evaluating purification strategies. GFP is a well-characterized model protein, used heavily in educational settings and by researchers with limited protein purification experience, and the data and strategies presented here may aid in

  6. High-performance liquid chromatography - Ultraviolet method for the determination of total specific migration of nine ultraviolet absorbers in food simulants based on 1,1,3,3-Tetramethylguanidine and organic phase anion exchange solid phase extraction to remove glyceride.

    PubMed

    Wang, Jianling; Xiao, Xiaofeng; Chen, Tong; Liu, Tingfei; Tao, Huaming; He, Jun

    2016-06-17

    The glyceride in oil food simulant usually causes serious interferences to target analytes and leads to failure of the normal function of the RP-HPLC column. In this work, a convenient HPLC-UV method for the determination of the total specific migration of nine ultraviolet (UV) absorbers in food simulants was developed based on 1,1,3,3-tetramethylguanidine (TMG) and organic phase anion exchange (OPAE) SPE to efficiently remove glyceride in olive oil simulant. In contrast to the normal ion exchange carried out in an aqueous solution or aqueous phase environment, the OPAE SPE was performed in the organic phase environments, and the time-consuming and challenging extraction of the nine UV absorbers from vegetable oil with aqueous solution could be readily omitted. The method was proved to have good linearity (r≥0.99992), precision (intra-day RSD≤3.3%), and accuracy(91.0%≤recoveries≤107%); furthermore, the lower limit of quantifications (0.05-0.2mg/kg) in five types of food simulants(10% ethanol, 3% acetic acid, 20% ethanol, 50% ethanol and olive oil) was observed. The method was found to be well suited for quantitative determination of the total specific migration of the nine UV absorbers both in aqueous and vegetable oil simulant according to Commission Regulation (EU) No. 10/2011. Migration levels of the nine UV absorbers were determined in 31 plastic samples, and UV-24, UV-531, HHBP and UV-326 were frequently detected, especially in olive oil simulant for UV-326 in PE samples. In addition, the OPAE SPE procedure was also been applied to efficiently enrich or purify seven antioxidants in olive oil simulant. Results indicate that this procedure will have more extensive applications in the enriching or purification of the extremely weak acidic compounds with phenol hydroxyl group that are relatively stable in TMG n-hexane solution and that can be barely extracted from vegetable oil.

  7. Anion exchange membrane adsorbers for flow-through polishing steps: Part II. Virus, host cell protein, DNA clearance, and antibody recovery.

    PubMed

    Weaver, Justin; Husson, Scott M; Murphy, Louise; Wickramasinghe, S Ranil

    2013-02-01

    Anion exchange membrane adsorbers are used for contaminant removal in flow-through polishing steps in the manufacture of biopharmaceuticals. This contribution describes the clearance of minute virus of mice, DNA, and host cell proteins by three commercially available anion-exchange membranes: Sartobind Q, Mustang Q, and ChromaSorb. The Sartobind Q and Mustang Q products contain quaternary amine ligands; whereas, ChromaSorb contains primary amine based ligands. Performance was evaluated over a range of solution conditions: 0-200 mM NaCl, pH 6.0-9.0, and flow rates of 4-20 membrane volumes/min in the presence and absence of up to 50 mM phosphate and acetate. In addition contaminant clearance was determined in the presence and absence of 5 g/L monoclonal antibody. The quaternary amine based ligands depend mainly on Coulombic interactions for removal of negatively charged contaminants. Consequently, performance of Sartobind Q and Mustang Q was compromised at high ionic strength. Primary amine based ligands in ChromaSorb enable high capacities at high ionic strength due to the presence of secondary, hydrogen bonding interactions. However, the presence of hydrogen phosphate ions leads to reduced capacity. Monoclonal antibody recovery using primary amine based anion-exchange ligands may be lower if significant binding occurs due to secondary interactions. The removal of a specific contaminant is affected by the level of removal of the other contaminants. The results of this study may be used to help guide selection of commercially available membrane absorbers for flow-through polishing steps.

  8. Sodium citrate-assisted anion exchange strategy for construction of Bi{sub 2}O{sub 2}CO{sub 3}/BiOI photocatalysts

    SciTech Connect

    Song, Peng-Yuan; Xu, Ming; Zhang, Wei-De

    2015-02-15

    Highlights: • Heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/BiOI microspheres were prepared via anion exchange. • Sodium citrate-assisted anion exchange for construction of composite photocatalysts. • Bi{sub 2}O{sub 2}CO{sub 3}/BiOI composites show high visible light photocatalytic activity. - Abstract: Bi{sub 2}O{sub 2}CO{sub 3}/BiOI heterojuncted photocatalysts were constructed through a facile partial anion exchange strategy starting from BiOI microspheres and urea with the assistance of sodium citrate. The content of Bi{sub 2}O{sub 2}CO{sub 3} in the catalysts was regulated by modulating the amount of urea as a precursor, which was decomposed to generate CO{sub 3}{sup 2−} in the hydrothermal process. Citrate anion plays a key role in controlling the morphology and composition of the products. The Bi{sub 2}O{sub 2}CO{sub 3}/BiOI catalysts display much higher photocatalytic activity than pure BiOI and Bi{sub 2}O{sub 2}CO{sub 3} towards the degradation of rhodamine B (RhB) and bisphenol A (BPA). The enhancement of photocatalytic activity of the heterojuncted catalysts is attributed to the formation of p–n junction between p-BiOI and n-Bi{sub 2}O{sub 2}CO{sub 3}, which is favorable for retarding the recombination of photoinduced electron-hole pairs. Moreover, the holes are demonstrated to be the main active species for the degradation of RhB and BPA.

  9. High Throughput Identification, Purification and Structural Characterization of Water Soluble Protein Complexes in Desulfovibrio vulgaris

    SciTech Connect

    Dong,, Ming; Han, Bong-Gyoon; Liu, Hui-Hai; Malik, J.; Geller, Jil; Yang, Li; Choi, M.; Chandonia, John-Marc; Arbelaez, Pablo; Sterling, H. J.; Typke, Dieter; Shatsky, Max; Brenner, Steve; Fisher, Susan; Williams, Evan; Szakal, Evelin; Allen, S.; Hall, S. C.; Hazen, Terry; Witkowska, H. E.; Jin, Jiming; Glaeser, Robert; Biggin, Mark

    2010-05-17

    Our scheme for the tagless purification of water soluble complexes. 10 g of protein from a crude bacterial extract is first fractionated by ammonium sulfate precipitation and then by a series of chromatographic steps: anion exchange (IEX), hydrophobic interaction (HIC), and finally size exclusion (Gel Filtration). Fractions from the last chromatography step are trypsin digested and peptides labeled with iTRAQ reagents to allow multiplexing and quantitation during mass spectrometric analysis. Elution profiles of identified proteins are then subjected to clustering analysis.

  10. Long-term performance of bicarbonate-form anion exchange: removal of dissolved organic matter and bromide from the St. Johns River, FL, USA.

    PubMed

    Walker, Krystal M; Boyer, Treavor H

    2011-04-01

    The goal of this research was to evaluate the long-term performance of magnetic ion exchange (MIEX) treatment using bicarbonate as the mobile counter ion (i.e., MIEX-HCO(3)) and sodium bicarbonate for regeneration. This work is important because there are many unknowns concerning the affinity and regeneration efficiency of bicarbonate-form anion exchange, whereas chloride-form anion exchange (i.e., MIEX-Cl resin) is well-studied. Raw water samples were collected approximately two times per month for one year from a single location on the St. Johns River (SJR), FL, USA. The SJR is characterized by high concentrations of dissolved organic carbon (DOC; 12-26 mg C/L) and bromide (550-1100 μg/L), and is being considered as an alternative drinking water supply. Jar tests were conducted using MIEX-HCO(3) resin, and MIEX-Cl resin was used as a baseline for comparison. The same batch of MIEX-HCO(3) and MIEX-Cl resin was used for the entire study, which was accomplished by regenerating the resins after each jar test in concentrated solutions of sodium bicarbonate and sodium chloride, respectively, and resulted in 21 regeneration cycles. Maximum removal efficiency was achieved with fresh MIEX-HCO(3) resin and virgin MIEX-Cl resin. Both forms of fresh/virgin MIEX resin also had the same affinity sequence with sulfate ≈ UV-absorbing substance > DOC > bromide. The removal efficiency of both forms of MIEX resin decreased as the number of regeneration cycles increased, with MIEX-HCO(3) resin showing 7-18% lower removals than MIEX-Cl resin after 21 regeneration cycles. The affinity sequence of regenerated MIEX-HCO(3) and MIEX-Cl resins differed from fresh resin with UV-absorbing substances > DOC > sulfate > bromide. Scanning electron microscopy and simulated MIEX-HCO(3) treatment under rapidly changing water quality were also used to improve the understanding of bicarbonate-form anion exchange. The major contribution of this research is a systematic study of the extended use of

  11. Preparation of Microvolume Anion-Exchange Cartridge for Inductively Coupled Plasma Mass Spectrometry-Based Determination of (237)Np Content in Spent Nuclear Fuel.

    PubMed

    Asai, Shiho; Hanzawa, Yukiko; Konda, Miki; Suzuki, Daisuke; Magara, Masaaki; Kimura, Takaumi; Ishihara, Ryo; Saito, Kyoichi; Yamada, Shinsuke; Hirota, Hideyuki

    2016-03-15

    Microvolume anion-exchange porous polymer disk-packed cartridges were prepared for Am/Np separation, which is required prior to the measurement of Neptunium-237 ((237)Np) with inductively coupled plasma mass spectrometry (ICPMS). Disks with a volume of 0.08 cm(3) were cut out from porous sheets having anion-exchange-group-containing polymer chains densely attached on the pore surface. Four different amine-based groups, N,N-dimethylaminoethyl methacrylate, trimethylammonium, diethylamine, and triethylenediamine (TEDA), were selected as the anion-exchange groups to be introduced into the porous sheets. The separation performances of Am/Np were evaluated using a standard solution of (243)Am, which had the same activity as its daughter nuclide (239)Np in secular equilibrium. (239)Np recovery of close to 100% with practically no contamination of (243)Am was achieved using the TEDA-introduced disk-packed cartridge. The time to elute (239)Np from the cartridge was approximately 40 s. The TEDA-introduced disk-packed cartridge was applied to the separation of Np from a spent nuclear fuel sample to confirm its separation performance. A known amount of (243)Am ((239)Np) was added to the spent nuclear fuel sample solution to monitor the chemical yield of Np. The chemical yield of Np calculated from a measured concentration of (239)Np was 90.4%. Am leakage in the Np-eluted solution was less than 1 ppt, corresponding to 0.001% of the original Am concentration in the sample. This indicates that no additional (239)Np was produced by the decay of the (243)Am remaining in the Np-eluted solution, thus providing a reliable chemical yield. U, which can cause a serious spectral interference involving the peak tail from the mass spectrum of (238)U, was thoroughly removed with the TEDA cartridge, providing interference-free measurement of (237)Np. The concentration of (237)Np obtained by ICPMS was 718 ± 12 ng/mg-U, which agrees well with the theoretically calculated value. Compared with

  12. Rapid formation of AgnX(X = S, Cl, PO4, C2O4) nanotubes via an acid-etching anion exchange reaction

    NASA Astrophysics Data System (ADS)

    Li, Jingjing; Yang, Wenlong; Ning, Jiqiang; Zhong, Yijun; Hu, Yong

    2014-05-01

    This work presents a rapid nanotube fabrication method for a series of silver compounds AgnX, such as Ag2S, AgCl, Ag3PO4, and Ag2C2O4, from pregrown Ag2CO3 nanorod templates. The anion exchange process involved takes place in non-aqueous solutions just at room temperature and completes within 10 minutes. An acid-etching anion exchange reaction mechanism has been proved underneath the transformation process from Ag2CO3 nanorods to AgnX nanotubes by the observation of an intermediate yolk-shell nanostructure. It has been found that the final structure of the products can be conveniently controlled by simply varying the concentration of HnX acids, and the organic solvents employed play a vital role in the formation of the nanotubes by effectively controlling the diffusion rates of different species of reacting ions. As a demonstration, the as-prepared AgCl and Ag3PO4 nanotubes exhibit enhanced photocatalytic activity and favorable recyclability for the photodegradation of rhodamine B (RhB) under visible-light irradiation.This work presents a rapid nanotube fabrication method for a series of silver compounds AgnX, such as Ag2S, AgCl, Ag3PO4, and Ag2C2O4, from pregrown Ag2CO3 nanorod templates. The anion exchange process involved takes place in non-aqueous solutions just at room temperature and completes within 10 minutes. An acid-etching anion exchange reaction mechanism has been proved underneath the transformation process from Ag2CO3 nanorods to AgnX nanotubes by the observation of an intermediate yolk-shell nanostructure. It has been found that the final structure of the products can be conveniently controlled by simply varying the concentration of HnX acids, and the organic solvents employed play a vital role in the formation of the nanotubes by effectively controlling the diffusion rates of different species of reacting ions. As a demonstration, the as-prepared AgCl and Ag3PO4 nanotubes exhibit enhanced photocatalytic activity and favorable recyclability for the

  13. Separation of small inorganic anions using methacrylate-based anion-exchange monolithic column prepared by low temperature UV photo-polymerization.

    PubMed

    Takahashi, Mutsumi; Hirano, Tomohiko; Kitagawa, Shinya; Ohtani, Hajime

    2012-04-06

    A methacrylate-based anion-exchange monolithic column was prepared by a single-step UV photo-copolymerization of [2-(methacryloyloxy)ethyl]-trimethyl ammonium chloride, butylmethacrylate, and ethylene dimethacrylate at a low temperature of -15 °C. The anion-exchange column exhibited good separation efficiency for the small inorganic anions of NO(2)(-), Br(-), NO(3)(-), and I(-) in the isocratic mode. Under the conditions optimized using a mobile phase of 50% ACN containing 100mM of NaCl, the theoretical plate heights of the anions were within the range of 12.2-15.6 μm (N, 64,000-82,000 m(-1); k, 0.2-1.6); and a value of 9.4 μm (N, 110,000 m(-1)) was achieved for t(0). The flow resistance of the column was acceptably low with a permeability of 2.7 × 10(-13) m(2). Fast gradient elution at a flow rate of 32 mm/s resulted in rapid and precise separation of the inorganic anions of IO(3)(-), NO(2)(-), Br(-), NO(3)(-), and I(-) within 20s.

  14. Vinylbenzyl quaternary ammonium-based polymeric monolith with hydrophilic interaction/strong anion exchange mixed-mode for pressurized capillary electrochromatography.

    PubMed

    Lin, Xucong; Feng, Shuhui; Jia, Wenchao; Ding, Kang; Xie, Zenghong

    2013-11-05

    A novel polymeric monolith with hydrophilic interaction and strong anion-exchange mixed-mode has been fabricated for pressurized capillary electrochromatography by an in situ copolymerization of vinylbenzyl trimethylammonium chloride (VBTA) and bisphenol A glycerolate dimethacrylate (BisGMA). The optimization of the polymerization mixture composition has been investigated, and column characteristics in terms of mechanical stability, permeability and reproducibility have been studied in detail. Linear responses between back pressure and flow rate have been achieved in different solvents. The absolute value of swelling propensity (SP) factor for poly(VBTA-co-BisGMA) monolith is 0.41, and the degree of permeability drop from pure ACN to water is about 45%. An acceptable mechanical stability of the column is obtained. The suitable reproducibility is also measured with the RSD for day-to-day (n=3) of retention time and column efficiency less than 3.3%, and the RSD for batch-to-batch (n=3) less than 5.3%, respectively. Under the optimum conditions, the mixed-mode of hydrophilic interaction and strong anion-exchange has been carried out, and efficient electrochromatography profiling of various polar compounds including neutral phenols, negatively charged benzoic acids and positively charged nucleic acid bases and nucleosides are achieved, respectively.

  15. Simultaneous separation of inorganic anions and cations by using anion-exchange and cation-exchange columns connected in tandem in ion chromatography.

    PubMed

    Karim, Khairil Juhanni Binti Abd; Jin, Ji-Ye; Takeuchi, Toyohide

    2003-05-02

    Inorganic anions and cations in environmental waters were determined by ion chromatography. Stationary and mobile phases were examined for the simultaneous separation of both anions and cations. Cations detection by UV detection requires a mobile phase with a UV absorbing additive, which indirectly visualizes cations as negative peaks. Simultaneous separation of anions and cations were achieved when using an eluent that consists of inorganic acid with weak basic amino acid as additives. It was convenient to separate both anions and cations by coupling anion-exchange and cation-exchange columns in tandem. The order of the separation columns connected affected the elution profiles. When the eluent comprises of multiple anions and a single cation, the anion-exchange column should be connected in the upper stream, whereas when the eluent comprises multiple cations and a single anion, the cation-exchange column should be connected in the upper stream. Use of switching valves also allowed simultaneous separation of anions and cations in a single chromatographic run. In the present work, operating conditions were optimized for the simultaneous separation of anions and cations.

  16. Combination of Na-modified zeolite and anion exchange resin for advanced treatment of a high ammonia-nitrogen content municipal effluent.

    PubMed

    Zhang, Haiyun; Li, Aimin; Zhang, Wei; Shuang, Chendong

    2016-04-15

    In this study, the exchange equilibrium and kinetic experiments of ammonia-nitrogen on the Na-form zeolite were conducted. The results indicated that the presence of humic acid have a negative effect on the equilibrium exchange capacity but have limited influence on the equilibrium time except shorten the sole intra-particle diffusion control time. The exchange equilibrium data could be well fitted by Freundlich model in the absence of humic acid but Langmuir model in the presence of humic acid. While the exchange kinetic data could be well described by pseudo-second-order kinetic model in both situations. An anion exchange resin exhibited high removal efficiency to humic acid and dissolved organic matter through kinetic results and fluorescence excitation-emission matrix (EEM) spectroscopy results. The use of the anion exchange resin prior to the Na-form zeolite improved the ammonia-nitrogen removal efficiency from 78% to 95% and increased the treatment volume of the Na-form zeolite from 51 BV (bed volume) to 76 BV. Both the resin and the Na-form zeolite could be successfully regenerated by the combination of alkaline and sodium chloride. Complete elution of ammonia-nitrogen was achieved when the mass percentage of sodium chloride and alkaline was 10% and 0.6% respectively.

  17. Monitoring of enzymatic hydrolysis of starch by microdialysis sampling coupled on-line to anion exchange chromatography and integrated pulsed electrochemical detection using post-column switching.

    PubMed

    Torto, N; Gorton, L; Marko-Varga, G; Emnéus, J; Akerberg, C; Zacchi, G; Laurell, T

    1997-12-05

    A quantitative evaluation of the hydrolysis of wheat starch using Termamyl, a thermostable alpha-amylase (endo-1,4-alpha-d-glucan, glucanohydrolase; EC 3.2.1.78), is reported. Data from the monitoring of the hydrolysis of wheat starch indicated that, after 1 h, glucose and maltooligosaccharides up to DP 7 were the main hydrolysis products and thus enabled optimization of a liquefication step during the production of L-lactic acid. The monitoring system used, both in the on- and off-line mode, was based on continuous flow microdialysis sampling (CFMS) coupled to anion exchange chromatography and integrated pulsed electrochemical detection (IPED). A microdialysis probe equipped with a 5-mm polysulfone (SPS 4005) membrane, with a molecular-weight cut-off of 5 kDa, was used to sample the hydrolysis products of native wheat starch at 90 degrees C. Characteristic fingerprint separations were achieved by anion exchange chromatography after enzymatic hydrolysis. Post-column switching improved the detection and, consequently, also quantification of the hydrolysates as fouling of the electrode could be reduced. Maltooligosaccharide standards were used for quantification and to verify the elution of the hydrolysates by spiking the off-line samples. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 546-554, 1997.

  18. Heterodimers formed through a partial anionic exchange process: scanning tunneling spectroscopy to monitor bands across the junction vis-à-vis photoinduced charge separation.

    PubMed

    Bera, Abhijit; Saha, Sudip K; Pal, Amlan J

    2015-11-07

    We report controlled formation of heterodimers and their charge separation properties. CdS|CdTe heterodimers were formed through an anionic exchange process of CdS nanostructures. With control over the duration of the anionic exchange process, bulk|dot, bulk|bulk, and then dot|bulk phases of the semiconductors could be observed to have formed. A mapping of density of states as derived from scanning tunneling spectroscopy (STS) brought out conduction and valence band-edges along the nanostructures and heterodimers. The CdS|CdTe heterodimers evidenced a type-II band-alignment between the semiconductors along with the formation of a depletion region at the interface. The width (of the depletion region) and the energy-offset at the interface depended on the size of the semiconductors. We report that the width that is instrumental for photoinduced charge separation in the heterodimers has a direct correlation with the performance of hybrid bulk-heterojunction solar cells based on the nanostructures in a polymer matrix.

  19. Surface- vs Diffusion-Limited Mechanisms of Anion Exchange in CsPbBr3 Nanocrystal Cubes Revealed through Kinetic Studies.

    PubMed

    Koscher, Brent A; Bronstein, Noah D; Olshansky, Jacob H; Bekenstein, Yehonadav; Alivisatos, A Paul

    2016-09-21

    Ion-exchange transformations allow access to nanocrystalline materials with compositions that are inaccessible via direct synthetic routes. However, additional mechanistic insight into the processes that govern these reactions is needed. We present evidence for the presence of two distinct mechanisms of exchange during anion exchange in CsPbX3 nanocrystals (NCs), ranging in size from 6.5 to 11.5 nm, for transformations from CsPbBr3 to CsPbCl3 or CsPbI3. These NCs exhibit bright luminescence throughout the exchange, allowing their optical properties to be observed in real time, in situ. The iodine exchange presents surface-reaction-limited exchanges allowing all anionic sites within the NC to appear chemically identical, whereas the chlorine exchange presents diffusion-limited exchanges proceeding through a more complicated exchange mechanism. Our results represent the first steps toward developing a microkinetic description of the anion exchange, with implications not only for understanding the lead halide perovskites but also for nanoscale ion exchange in general.

  20. Use of a new tandem cation/anion exchange system with clinical-scale generators provides high specific volume solutions of technetium-99m and rhenium-188

    SciTech Connect

    Knapp, F.R. Jr.; Beets, A.L.; Mirzadeh, S.; Guhlke, S. |

    1998-03-01

    In this paper the authors describe the first application of a simple and inexpensive post elution tandem cation-anion exchange column system which is based on generator elution with salts of weak acids such as ammonium acetate instead of saline solution to provide very high specific volume solutions of technetium-99m and rhenium-188 from clinical scale molybdenum-99/technetium-99m generator prepared from low specific activity (n,y) molybdenum-99, and tungsten-188/rhenium-188 generators, respectively. Initial passage of the bolus through a strong cation exchange cartridge converts the ammonium acetate to acetic acid which is essentially not ionized at the acidic pH, allowing specific subsequent amine type (QMA SepPak{trademark}) anion exchange cartridge column trapping of the microscopic levels of the pertechnetate or perrhenate. Subsequent elution of the anion cartridge with a small volume (< 1 mL) of saline then provides high specific volume solutions of technetium-99m by concentration of the high eluant volumes obtained by elution of clinical-scale (1 Ci) generators. This new approach also works very effectively to obtain high specific volume solutions of rhenium-188 (> 500 mCi/mL) from the alumina-based tungsten-188/rhenium-188 generator.

  1. Single vial sample preparation of markers of nerve agents by dispersive solid-phase extraction using magnetic strong anion exchange resins.

    PubMed

    Singh, Varoon; Chinthakindi, Sridhar; Purohit, Ajay Kumar; Pardasani, Deepak; Tak, Vijay; Dubey, Devendra Kumar

    2015-05-22

    A sample preparation method involving extraction, enrichment and derivatization of acidic degradation products of nerve agents was developed using magnetic strong anion exchange resins (MSAX). The method was performed in a single vial involving magnetic dispersive solid phase extraction (MDSPE). Analytes were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) in the presence of resins. MSAX were custom synthesized using Fe3O4 nanoparticles as core, 4-vinylpyridine-co-divinylbenzene as polymer shell and quaternary pyridinium function as anion-exchanger. Hydroxide ions were the counter-anions of MSAX to effectively capture the acidic alkyl alkylphosphonic acids (AAPAs) and alkylphosphonic acids (APAs). Quantitative measurements of analytes were performed in the selected ion monitoring mode of GC-MS. Full scan mode of analysis was followed for identifications. Under the optimized conditions analytes were recovered in the range of 39.7-98.8% (n=3, relative standard deviations (RSD) from 0.3 to 6.5%). Limits of detection (LODs) were in the range of 0.1-1.1ngmL(-1); and the linear dynamic range was 5-1000ngmL(-1) with r(2) of 0.9977-0.9769. Applicability of the method was tested with rain-, tap-, muddy-water and Organization for Prohibition of Chemical Weapons (OPCW) Proficiency Test samples.

  2. Spectroscopic characterization by photodiode array detection of human urinary and amniotic protein HC subpopulations fractionated by anion-exchange and size-exclusion high-performance liquid chromatography.

    PubMed

    Calero, M; Escribano, J; Soriano, F; Grubb, A; Brew, K; Méndez, E

    1996-01-05

    A procedure for spectroscopic characterization and partial fractionation of human protein HC populations by high-performance liquid chromatography-photodiode array ultraviolet-visible detection is reported. Human protein HC from urine or amniotic fluid fractionated by anion-exchange HPLC in a protein Pak DEAE 5PW appeared to be heterogeneous as judged by the asymmetric elution pattern, consisting of a continuous irregular broad peak with several shoulders distributed along the whole chromatogram. Selected fractions containing shoulders were rechromatographed and finally six symmetrical homogeneous peaks with different retention times were obtained from each protein HC preparation. The direct automatic absorption spectra analyses at each peak maximum, indicated that all of the homogeneous peaks seemed to be protein HC, all of them associated to the same chromophore although with different stoichiometry ratios. Isoelectric focusing showed that each peak was composed of a limited number of subpopulations of protein HC with different isoelectric points. Size microheterogeneity has been also demonstrated in both urinary and amniotic protein HC preparations by a combination of size-exclusion HPLC on a TSK 3000 SW6 column and photodiode array detection. Partial fractionation of human albumin on an analytical anion-exchange Mono-Q PC 1.6/5 column, has allowed the identification of heterogeneous chromophore-containing populations displaying significant absorption in the visible region in resemblance to that of protein HC.

  3. Evaluation of an anion exchange resin-based method for concentration of F-RNA coliphages (enteric virus indicators) from water samples.

    PubMed

    Pérez-Méndez, A; Chandler, J C; Bisha, B; Goodridge, L D

    2014-08-01

    Enteric viral contaminants in water represent a public health concern, thus methods for detecting these viruses or their indicator microorganisms are needed. Because enteric viruses and their viral indicators are often found at low concentrations in water, their detection requires upfront concentration methods. In this study, a strong basic anion exchange resin was evaluated as an adsorbent material for the concentration of F-RNA coliphages (MS2, Qβ, GA, and HB-P22). These coliphages are recognized as enteric virus surrogates and fecal indicator organisms. Following adsorption of the coliphages from 50ml water samples, direct RNA isolation and real time RT-PCR detection were performed. In water samples containing 10(5)pfu/ml of the F-RNA coliphages, the anion exchange resin (IRA-900) adsorbed over 96.7% of the coliphages present, improving real time RT-PCR detection by 5-7 cycles compared to direct testing. F-RNA coliphage RNA recovery using the integrated method ranged from 12.6% to 77.1%. Resin-based concentration of samples with low levels of the F-RNA coliphages allowed for 10(0)pfu/ml (MS2 and Qβ) and 10(-1)pfu/ml (GA and HB-P22) to be detected. The resin-based method offers considerable advantages in cost, speed, simplicity and field adaptability.

  4. The influence of plutonium concentration and solution flow rate on the effective capacity of macroporous anion exchange resin. [Lewatit MP-500-FK; Pu/sup +/

    SciTech Connect

    Marsh, S.F.; Gallegos, T.D.

    1987-07-01

    The principal aqueous process used to recover and purify plutonium at the Los Alamos Plutonium Facility is anion exchange in nitric acid. Previous studies with gel-type anion exchange resin have shown an inverse relationship between plutonium concentration in the feed solution and the optimum flow rate for this process. Because gel-type resin has been replaced with macroporous resin at Los Alamos, the relationship between plutonium concentration and solution flow rate was reexamined with the selected Lewatit MP-500-FK resin using solutions of plutonium in nitric acid and in nitric acid with high levels of added nitrate salts. Our results with this resin differ significantly from previous data obtained with gel-type resin. Flow-rate variation from 10 to 80 liters per hour had essentially no effect on the measured quantities of plutonium sorbed by the macroporous resin. However, the effect of plutonium concentration in the feed solutions was pronounced, as feed solutions that contained the highest concentrations of plutonium also produced the highest resin loadings. The most notable effect of high concentrations of dissolved nitrate salts in these solutions was an increased resin capacity for plutonium at low flow rates. 16 refs., 7 figs., 2 tabs.

  5. Synthesis, anion exchange, and delamination of Co-Al layered double hydroxide: assembly of the exfoliated nanosheet/polyanion composite films and magneto-optical studies.

    PubMed

    Liu, Zhaoping; Ma, Renzhi; Osada, Minoru; Iyi, Nobuo; Ebina, Yasuo; Takada, Kazunori; Sasaki, Takayoshi

    2006-04-12

    This paper describes a systematic study on the synthesis, anion exchange, and delamination of Co-Al layered double hydroxide (LDH), with the aim of achieving fabrication and clarifying the properties of LDH nanosheet/polyanion composite films. Co-Al-CO3 LDH hexagonal platelets of 4 mum in lateral size were synthesized by the urea method under optimized reaction conditions. The as-prepared CO3(2-)-LDH was converted to Cl- -LDH by treating with a NaCl-HCl mixed solution, retaining its high crystallinity and hexagonal platelike morphology. LDHs intercalated with a variety of anions (such as NO3-, ClO4-, acetate, lactate, dodecyl sulfate, and oleate) were further prepared from Cl- -LDH via an anion-exchange process employing corresponding salts. Exchanged products in various anion forms were found to show different delamination behaviors in formamide. Among them, best results were observed for NO3- -LDH in terms of the exfoliating degree and the quality of the exfoliated nanosheets. The delamination gave a pink transparent suspension containing well-defined nanosheets with lateral sizes of up to 2 microm. The resulting nanosheets were assembled layer-by-layer with an anionic polymer, poly(sodium styrene 4-sulfonate) (PSS), onto quartz glass substrates to produce composite films. Magnetic circular dichroism (MCD) measurements revealed that the assembled multilayer films exhibited an interesting magneto-optical response.

  6. Monitoring of enzymatic hydrolysis of starch by microdialysis sampling coupled on-line to anion exchange chromatography and integrated pulsed electrochemical detection using post-column switching

    SciTech Connect

    Torto, N.; Gorton, L.; Emneus, J.; Laurell, T.; Marko-Varga, G.; Akerberg, C.; Zacchi, G. |

    1997-12-05

    A quantitative evaluation of the hydrolysis of wheat starch using Termamyl, a thermostable {alpha}-amylase, is reported. Data from the monitoring of the hydrolysis of wheat starch indicated that, after 1 h, glucose and maltooligosaccharides up to DP 7 were the main hydrolysis products and thus enabled optimization of a liquefaction step during the production of L-lactic acid. The monitoring system used, both in the on- and off-line mode, was based on continuous flow microdialysis sampling (CFMS) coupled to anion exchange chromatography and integrated pulsed electrochemical detection (IPED). A microdialysis probe equipped with a 5-mm polysulfone (SPS 4005) membrane, with a molecular-weight cut-off of 5 kDa, was used to sample the hydrolysis products of native wheat starch at 90 C. Characteristic fingerpoint separations were achieved by anion exchange chromatography after enzymatic hydrolysis. Post-column switching improved the detection and, consequently, also quantification of the hydrolysates as fouling of the electrode could be reduced. Maltooligosaccharide standards were used for quantification and to verify the elution of the hydrolysates by spiking the off-line samples.

  7. Rapid formation of Ag(n)X(X = S, Cl, PO4, C2O4) nanotubes via an acid-etching anion exchange reaction.

    PubMed

    Li, Jingjing; Yang, Wenlong; Ning, Jiqiang; Zhong, Yijun; Hu, Yong

    2014-06-07

    This work presents a rapid nanotube fabrication method for a series of silver compounds AgnX, such as Ag2S, AgCl, Ag3PO4, and Ag2C2O4, from pregrown Ag2CO3 nanorod templates. The anion exchange process involved takes place in non-aqueous solutions just at room temperature and completes within 10 minutes. An acid-etching anion exchange reaction mechanism has been proved underneath the transformation process from Ag2CO3 nanorods to AgnX nanotubes by the observation of an intermediate yolk-shell nanostructure. It has been found that the final structure of the products can be conveniently controlled by simply varying the concentration of HnX acids, and the organic solvents employed play a vital role in the formation of the nanotubes by effectively controlling the diffusion rates of different species of reacting ions. As a demonstration, the as-prepared AgCl and Ag3PO4 nanotubes exhibit enhanced photocatalytic activity and favorable recyclability for the photodegradation of rhodamine B (RhB) under visible-light irradiation.

  8. Silica-based monolithic columns with mixed-mode reversed-phase/weak anion-exchange selectivity principle for high-performance liquid chromatography.

    PubMed

    Nogueira, Raquel; Lubda, Dieter; Leitner, Alexander; Bicker, Wolfgang; Maier, Norbert M; Lämmerhofer, Michael; Lindner, Wolfgang

    2006-05-01

    This article describes the synthesis, chromatographic characterization, and performance evaluation of analytical (100 x 4.6 mm id) and semipreparative (100 x 10 mm id) monolithic silica columns with mixed-mode RP/weak anion-exchange (RP/WAX) surface modification. The monolithic RP/WAX columns were obtained by immobilization of N-(10-undecenoyl)-3-aminoquinuclidine onto thiol-modified monolithic silica columns (Chromolith) by a radical addition reaction. Their chromatographic characterization by Engelhardt and Tanaka tests revealed slightly lower hydrophobic selectivities than C-8 phases, as well as higher polarity and also improved shape selectivity than RP-18e silica rods. The surface modification enabled separation by both RP and anion-exchange chromatography principles, and thus showed complementary selectivities to the RP-18e monoliths. The mixed-mode monoliths have been tested for the separation of peptides and turned out to be particularly useful for hydrophilic acidic peptides, which are usually insufficiently retained on RP-18e monolithic columns. Compared to a corresponding particulate RP/WAX column (5 microm, 10 nm pore diameter), the analytical RP/WAX monolith caused lower system pressure drops and showed, as expected, higher efficiency (e.g. by a factor of about 2.5 lower C-term for a tetrapeptide). The upscaling from the analytical to semipreparative column dimension was also successful.

  9. A novel surface-confined glucaminium-based ionic liquid stationary phase for hydrophilic interaction/anion-exchange mixed-mode chromatography.

    PubMed

    Qiao, Lizhen; Wang, Shuangyuan; Li, Hua; Shan, Yuanhong; Dou, Abo; Shi, Xianzhe; Xu, Guowang

    2014-09-19

    Glucaminium-based ionic liquids are a new class of recently developed ionic liquids and prepared by functionalizing the amine group of N-methyl-d-glucamine, which renders them good hydrophilicity due to the presence of the glucose structure and charged quaternary ammonium group. In the present study, a glucaminium-based ionic liquid N,N-diallyl-N-methyl-d-glucaminium bromide was synthesized and subsequently bonded to the surface of 3-mercaptopropyl modified silica materials through "thiol-ene" click chemistry. The obtained stationary phase was characterized by elemental analysis and infrared spectroscopy, and then packed as a HPLC column. A mixture of five nucleosides was used to characterize the separation performance of the obtained column under HILIC mode and the column efficiency was determined with cytidine as the test solute, reaching 80,000plates/m. Then, the retention behavior was evaluated by investigating the effect of various chromatographic factors on retention of different types of solutes, and the results revealed that the developed surface-confined glucaminium-based ionic liquid stationary phase exhibited a hydrophilic interaction/anion-exchange mixed-mode retention mechanism. Finally, two mixtures of nucleotides and flavonoids were separated on the glucaminium-based ionic liquid column, respectively under hydrophilic interaction and hydrophilic interaction/anion-exchange mixed-mode chromatography. In conclusion, the multimodal retention capabilities of the glucaminium-based ionic liquid column could offer a wider range of retention behavior and flexible selectivity toward polar and hydrophilic compounds.

  10. Ion-exchange chromatography: basic principles and application to the partial purification of soluble mammalian prolyl oligopeptidase.

    PubMed

    Cummins, Philip M; Dowling, Oonagh; O'Connor, Brendan F

    2011-01-01

    Ion-exchange chromatography (IEC) allows for the separation of ionizable molecules on the basis of differences in charge properties. Its large sample-handling capacity, broad applicability (particularly to proteins and enzymes), moderate cost, powerful resolving ability, and ease of scale-up and automation have led to it becoming one of the most versatile and widely used of all liquid chromatography (LC) techniques. In this chapter, we review the basic principles of IEC, as well as the broader criteria for selecting IEC conditions. By way of further illustration, we outline protocols necessary to partially purify a serine peptidase from bovine whole brain cytosolic fraction, covering crude tissue extract preparation through to partial purification of the target enzyme using anion-exchange chromatography. Protocols for assaying total protein and enzyme activity in both pre- and post-IEC fractions are also described. The target serine peptidase, prolyl oligopeptidase (POP, EC3.4.21.26), is an 80-kDa enzyme with endopeptidase activity towards peptide substrates of ≤30 amino acids. POP is a ubiquitous post-proline cleaving enzyme with particularly high expression levels in the mammalian brain, where it participates in the metabolism of neuroactive peptides and peptide-like hormones (e.g. thyroliberin, gonadotropin-releasing hormone).

  11. AUTOSEP, an automated system for the quantitative ion exchange separation of plutonium from impurities

    SciTech Connect

    Freeman, B.P.; Weiss, J.R.; Pietri, C.E.

    1981-08-01

    The anion exchange separation of interfering impurities from plutonium in the Dowex-1 8 N HNO/sub 3/ system is a reliable purification method. An automated system, AUTOSEP, based on this manual procedure has been developed for greater productivity. Samples, in groups of ten, each containing 5--10 mg of plutonium are processed automatically in this system. AUTOSEP incorporates a means of programming reagent delivery, adjustment of the sample to the plutonium (IV) oxidation state via Fe(II) reduction/HNO/sub 3/ oxidation, plutonium sorption on the resin in 8 N HNO/sub 3/, washing of the resin bed with 8 N HNO/sub 3/ to remove impurities, elution of the purified plutonium with 0.36 N HCl--0.01 N HF, and waste effluent disposal. The reagents are delivered by gravity from a module whose only moving parts are rotary valves. The eluted plutonium solutions are collected for subsequent controlled-potential coulometric analysis. The average recovery of plutonium determined by controlled-potential coulometry using this apparatus was 100.00% with a relative standard deviation of 0.10%.

  12. Qualitative and quantitative analysis of branches in dextran using high-performance anion exchange chromatography coupled to quadrupole time-of-flight mass spectrometry.

    PubMed

    Yi, Lin; Ouyang, Yilan; Sun, Xue; Xu, Naiyu; Linhardt, Robert J; Zhang, Zhenqing

    2015-12-04

    Dextran, a family of natural polysaccharides, consists of an α (1→6) linked-glucose main (backbone) chain having a number of branches. The determination of the types and the quantities of branches in dextran is important in understanding its various biological roles. In this study, a hyphenated method using high-performance anion exchange chromatography (HPAEC) in parallel with pulsed amperometric detection (PAD) and mass spectrometry (MS) was applied to qualitative and quantitative analysis of dextran branches. A rotary cation-exchange cartridge array desalter was used for removal of salt from the HPAEC eluent making it MS compatible. MS and MS/MS were used to provide structural information on the enzymatically prepared dextran oligosaccharides. PAD provides quantitative data on the ratio of enzyme-resistant, branched dextran oligosaccharides. Both the types and degree of branching found in a variety of dextrans could be simultaneously determined online using this method.

  13. Determination of sucralose in Splenda and a sugar-free beverage using high-performance anion-exchange chromatography with pulsed amperometric detection.

    PubMed

    Hanko, Valoran P; Rohrer, Jeffrey S

    2004-07-14

    Sucralose is a chlorinated carbohydrate nonnutritive sweetener of food and beverage products. The determination of sucralose in food and beverages is important to ensure consistency in product quality. Sucralose was determined in two commercial products without sample preparation using high-performance anion-exchange (HPAE) chromatography coupled with pulsed amperometric detection (PAD). Sucralose was determined with a 10 min isocratic separation. To determine sucralose and other carbohydrates (e.g., dextrose) simultaneously, a gradient separation was developed. The linear range of electrochemical response extended over 3 orders of magnitude, from 0.01 (LOD) to 40 microM (16 microg/mL; 25 microL injection). High precision, high spike recovery, and method ruggedness were observed for both samples.

  14. Preparation and evaluation of 2-methylimidazolium-functionalized silica as a mixed-mode stationary phase for hydrophilic interaction and anion-exchange chromatography.

    PubMed

    Yang, Beibei; Liu, Houmei; Chen, Jia; Guan, Ming; Qiu, Hongdeng

    2016-10-14

    In this paper, a novel 2-methylimidazolium-functionalized silica stationary phase was prepared and further used for hydrophilic interaction and anion-exchange mixed-mode chromatography. The stationary phase was characterized by elemental analysis and Fourier transform infrared spectrometry. The chromatographic properties of this stationary phase were investigated by hydrophilic chromatography for the separation of nucleosides, nucleobases, water soluble vitamins, sulfonamides and saccharides, and ion chromatography for the separation of inorganic anions. The effect of acetonitrile content, salt concentration and pH values of the mobile phase on the retention of the stationary phases was also investigated. Compared with 1-methylimidazolium-functionalized silica stationary phase, this new stationary phase demonstrated similar or better separation selectivity. This new column demonstrated good performance and separation selectivity even better than a commercial hydrophilic column. Besides, 2-methylimidazolium-functionalized silica is possible to be modified again and used as a precursor to derivate some new stationary phases from the 3-position nitrogen.

  15. [Effects and mechanism on removing organics and reduction of membrane fouling using granular macro-porous anion exchange resin in drinking water treatment].

    PubMed

    He, Huan; Dong, Bing-Zhi; Xu, Guang-Hong; Yan, Zhao-Hui

    2014-05-01

    A granular macro-porous anion exchange resin combined with coagulation was used as pretreatment of microfiltration membrane, and their effects and mechanism on removing organics and reduction of membrane fouling were evaluated. The results showed that resin could be effective in removing organics with medium and small molecular weight ( Mr) but ineffective in removing organics with large Mr, while couagulation could significantly remove organics with large Mr, with a limited removal for organics with medium and small Mr. Using resin alone as pretreatment could be effective in removal of organics but limited in reduction of membrane fouling. With combination of coagulation and resin as pretreatment of microfiltration, not only organics could be removed effectively, but also membrane fouling could be reduced.

  16. Band 3, the human red cell chloride/bicarbonate anion exchanger (AE1, SLC4A1), in a structural context.

    PubMed

    Reithmeier, Reinhart A F; Casey, Joseph R; Kalli, Antreas C; Sansom, Mark S P; Alguel, Yilmaz; Iwata, So

    2016-07-01

    The crystal structure of the dimeric membrane domain of human Band 3(1), the red cell chloride/bicarbonate anion exchanger 1 (AE1, SLC4A1), provides a structural context for over four decades of studies into this historic and important membrane glycoprotein. In this review, we highlight the key structural features responsible for anion binding and translocation and have integrated the following topological markers within the Band 3 structure: blood group antigens, N-glycosylation site, protease cleavage sites, inhibitor and chemical labeling sites, and the results of scanning cysteine and N-glycosylation mutagenesis. Locations of mutations linked to human disease, including those responsible for Southeast Asian ovalocytosis, hereditary stomatocytosis, hereditary spherocytosis, and distal renal tubular acidosis, provide molecular insights into their effect on Band 3 folding. Finally, molecular dynamics simulations of phosphatidylcholine self-assembled around Band 3 provide a view of this membrane protein within a lipid bilayer.

  17. Identification of PCR-amplified genetically modified organisms (GMOs) DNA by peptide nucleic acid (PNA) probes in anion-exchange chromatographic analysis.

    PubMed

    Rossi, Stefano; Lesignoli, Francesca; Germini, Andrea; Faccini, Andrea; Sforza, Stefano; Corradini, Roberto; Marchelli, Rosangela

    2007-04-04

    PCR products obtained by selective amplification of transgenic DNA derived from food samples containing Roundup Ready soybean or Bt-176 maize have been analyzed by anion-exchange HPLC. Peptide nucleic acids (PNAs), oligonucleotide analogues known to bind to complementary single-stranded DNA with high affinity and specificity, have been used as specific probes in order to assess the identity of the peaks observed. Two different protocols were adopted in order to obtain single-stranded DNA: amplification with an excess of one primer or digestion of one DNA strand. The single-stranded DNA was mixed with the PNA probe, and the presence of a specific sequence was revealed through detection of the corresponding PNA:DNA peak with significantly different retention time. Advantages and limits of this approach are discussed. The method was tested with reference materials and subsequently applied to commercial samples.

  18. Tuned synthesis of two coordination polymers of Cd(II) using substituted bent 3-pyridyl linker and succinate: structures and their applications in anion exchange and sorption properties.

    PubMed

    Maity, Dilip Kumar; Bhattacharya, Biswajit; Halder, Arijit; Ghoshal, Debajyoti

    2015-12-28

    Two new Cd(II) coordination polymers, namely [Cd(3-bpdh)2(ClO4)2]n (1) and {[Cd(3-bpdh)(suc)(H2O)]·3(H2O)}n (2), have been synthesized using a substituted bent N,N'-donor ligand 2,5-bis-(3-pyridyl)-3,4-diaza-2,4-hexadiene (3-bpdh) and aliphatic dicarboxylate disodium succinate (suc) with Cd(II) perchlorate salts at room temperature by a slow diffusion technique for the exploration of our previous reported work. Both the structures were determined by single-crystal X-ray diffraction analysis and also by other physicochemical methods. Structure analysis revealed that complex 1 is a 1D chain structure containing coordinated perchlorate with a metal centre, and complex 2 shows a porous 3D framework with encapsulation of lattice water molecules into the void along the crystallographic a-axis. The PXRD study shows the bulk purity of both the complexes and TGA analysis of 2 exhibits that the structure is thermally stable up to 250 °C. Complex 1 shows a nice anion exchange property with replacement of weakly coordinated perchlorate with the inclusion of new anions; and the anion exchanged solids were characterised by FT-IR, PXRD and photoluminescence properties. The desolvated framework of 2 exhibits sorption of CO2 and water vapor and surface adsorption of N2 corroborating with the nature of the pore environment present in 2. The photoluminescence study has been also done for both complexes in the solid state which exhibits ligand based emissions at room temperature.

  19. Sulfur geochemistry of hydrothermal waters in Yellowstone National Park, Wyoming, USA. III. An anion-exchange resin technique for sampling and preservation of sulfoxyanions in natural waters

    USGS Publications Warehouse

    Druschel, G.K.; Schoonen, M.A.A.; Nordstorm, D.K.; Ball, J.W.; Xu, Y.; Cohn, C.A.

    2003-01-01

    A sampling protocol for the retention, extraction, and analysis of sulfoxyanions in hydrothermal waters has been developed in the laboratory and tested at Yellowstone National Park and Green Lake, NY. Initial laboratory testing of the anion-exchange resin Bio-Rad??? AG1-X8 indicated that the resin was well suited for the sampling, preservation, and extraction of sulfate and thiosulfate. Synthetic solutions containing sulfate and thiosulfate were passed through AG1-X8 resin columns and eluted with 1 and 3 M KCl, respectively. Recovery ranged from 89 to 100%. Comparison of results for water samples collected from five pools in Yellowstone National Park between on-site IC analysis (U.S. Geological Survey mobile lab) and IC analysis of resin-stored sample at SUNY-Stony Brook indicates 96 to 100% agreement for three pools (Cinder, Cistern, and an unnamed pool near Cistern) and 76 and 63% agreement for two pools (Sulfur Dust and Frying Pan). Attempts to extract polythionates from the AG1-X8 resin were made using HCl solutions, but were unsuccessful. Bio-Rad??? AG2-X8, an anion-exchange resin with weaker binding sites than the AG1-X8 resin, is better suited for polythionate extraction. Sulfate and thiosulfate extraction with this resin has been accomplished with KCl solutions of 0.1 and 0.5 M, respectively. Trithionate and tetrathionate can be extracted with 4 M KCl. Higher polythionates can be extracted with 9 M hydrochloric acid. Polythionate concentrations can then be determined directly using ion chromatographic methods, and laboratory results indicate recovery of up to 90% for synthetic polythionate solutions using AG2-X8 resin columns. ?? The Royal Society of Chemistry and the Division of Geochemistry of the American Chemical Society 2003.

  20. Surface charge fine tuning of reversed-phase/weak anion-exchange type mixed-mode stationary phases for milder elution conditions.

    PubMed

    Zimmermann, Aleksandra; Horak, Jeannie; Sánchez-Muñoz, Orlando L; Lämmerhofer, Michael

    2015-08-28

    A series of new mixed-mode reversed-phase/weak anion-exchange (RP/WAX) phases have been synthesized by immobilization of N-undecenyl-3-α-aminotropane onto thiol-modified silica gel by thiol-ene click chemistry and subsequent introduction of acidic thiol-endcapping functionalities of different type and surface densities. Click chemistry allowed to adjust a controlled surface concentration of the RP/WAX ligand in such a way that a sufficient quantity of residual thiols remained unmodified which have been capped by thiol click with either 3-butenoic acid or allylsulfonic acid as co-ligands. In another embodiment, performic acid oxidation of N-undecenyl-3-α-aminotropane-derivatized thiol-modified silica gave a RP/WAX phase with high density of sulfonic acid end-capping groups. ζ-Potential determinations confirmed the fine-tuned pI of these mixed-mode stationary phases which was shifted from 9.5 to 8.2, 7.8, and 6.5 with 3-butenoic acid and allylsulfonic acid end-capping as well as performic acid oxidation. For acidic solutes, the co-ionic endcapping leads to strongly reduced retention times and clearly allowed elution of these analytes under lower ionic strength thus milder elution conditions. In spite of the acidic endcapping, the new mixed-mode phases maintained their hydrophobic and anion-exchange selectivity as well as their multimodal nature featuring RP and HILIC elution domains at acetonitrile percentages below and above 50%, respectively. Column classification by principal component analysis of an extended retention map in comparison to a set of polar commercial and in-house synthesized stationary phases confirmed complementarity of the new mixed-mode phases with respect to HILIC, polar RP, amino and commercial mixed-mode phases.

  1. The automated radiosynthesis and purification of the opioid receptor antagonist, [6-O-methyl-11C]diprenorphine on the GE TRACERlab FXFE radiochemistry module.

    PubMed

    Fairclough, Michael; Prenant, Christian; Brown, Gavin; McMahon, Adam; Lowe, Jonathan; Jones, Anthony

    2014-05-15

    [6-O-Methyl-(11)C]diprenorphine ([(11)C]diprenorphine) is a positron emission tomography ligand used to probe the endogenous opioid system in vivo. Diprenorphine acts as an antagonist at all of the opioid receptor subtypes, that is, μ (mu), κ (kappa) and δ (delta). The radiosynthesis of [(11)C]diprenorphine using [(11)C]methyl iodide produced via the 'wet' method on a home-built automated radiosynthesis set-up has been described previously. Here, we describe a modified synthetic method to [(11)C]diprenorphine performed using [(11)C]methyl iodide produced via the gas phase method on a GE TRACERlab FXFE radiochemistry module. Also described is the use of [(11)C]methyl triflate as the carbon-11 methylating agent for the [(11)C]diprenorphine syntheses. [(11)C]Diprenorphine was produced to good manufacturing practice standards for use in a clinical setting. In comparison to previously reported [(11)C]diprenorphine radiosyntheisis, the method described herein gives a higher specific activity product which is advantageous for receptor occupancy studies. The radiochemical purity of [(11)C]diprenorphine is similar to what has been reported previously, although the radiochemical yield produced in the method described herein is reduced, an issue that is inherent in the gas phase radiosynthesis of [(11)C]methyl iodide. The yields of [(11)C]diprenorphine are nonetheless sufficient for clinical research applications. Other advantages of the method described herein are an improvement to both reproducibility and reliability of the production as well as simplification of the purification and formulation steps. We suggest that our automated radiochemistry route to [(11)C]diprenorphine should be the method of choice for routine [(11)C]diprenorphine productions for positron emission tomography studies, and the production process could easily be transferred to other radiochemistry modules such as the TRACERlab FX C pro.

  2. Evaluation of Novel Wet Chemistry Separation and Purification Methods to Facilitate Automation of Astatine-­211 Isolation

    SciTech Connect

    Wilbur, Daniel Scott

    2016-07-19

    At solutions did not appear to change the percent capture, but may have an effect on the % extracted; There was some indication that the PEG-­Merrifield resins could be saturated (perhaps with Bi) resulting in lower capture percentages, but more studies need to be done to confirm that; A target dissolution chamber, designed and built at PNNL, works well with syringe pumps so it can be used in an automated system; Preliminary semi-­automated 211At isolation studies have been conducted with full scale target dissolution and 211At isolation using a PEG column on the Hamilton automated system gave low overall recoveries, but HNO3 was used (rather than HCl) for loading the 211At and flow rates were not optimized; Results obtained using PEG columns are high enough to warrant further development on a fully automated system; Results obtained also indicate that additional studies are warranted to evaluate other types of columns for 211At separation from bismuth, which allow use of HNO3/HCl mixtures for loading and NaOH for eluting 211At. Such a column could greatly simplify the overall isolation process and make it easier to automate.

  3. Determination of free sulfites (SO3-2) in dried fruits processed with sulfur dioxide by ion chromatography through anion exchange column and conductivity detection.

    PubMed

    Liao, Benjamin S; Sram, Jacqueline C; Files, Darin J

    2013-01-01

    A simple and effective anion ion chromatography (IC) method with anion exchange column and conductivity detector has been developed to determine free sulfites (SO3-2) in dried fruits processed with sulfur dioxide. No oxidation agent, such as hydrogen peroxide, is used to convert sulfites to sulfates for IC analysis. In addition, no stabilizing agent, such as formaldehyde, fructose or EDTA, is required during the sample extraction. This method uses aqueous 0.2 N NaOH as the solvent for standard preparation and sample extraction. The sulfites, either prepared from standard sodium sulfite powder or extracted from food samples, are presumed to be unbound SO3-2 in aqueous 0.2 N NaOH (pH > 13), because the bound sulfites in the sample matrix are released at pH > 10. In this study, sulfites in the standard solutions were stable at room temperature (i.e., 15-25 degrees C) for up to 12 days. The lowest standard of the linear calibration curve is set at 1.59 microg/mL SO3-2 (equivalent to 6.36 microg/g sample with no dilution) for analysis of processed dried fruits that would contain high levels (>1000 microg/g) of sulfites. As a consequence, this method typically requires significant dilution of the sample extract. Samples are prepared with a simple procedure of sample compositing, extraction with aqueous 0.2 N NaOH, centrifugation, dilution as needed, and filtration prior to IC. The sulfites in these sample extracts are stable at room temperature for up to 20 h. Using anion IC, the sulfites are eluted under isocratic conditions with 10 mM aqueous sodium carbonate solution as the mobile phase passing through an anion exchange column. The sulfites are easily separated, with an analysis run time of 18 min, regardless of the dried fruit matrix. Recoveries from samples spiked with sodium sulfites were demonstrated to be between 81 and 105% for five different fruit matrixes (apricot, golden grape, white peach, fig, and mango). Overall, this method is simple to perform and

  4. Interaction of amphiphiles with integral membrane proteins. II. A simple, minimal model for the nonspecific interaction of amphiphiles with the anion exchanger of the erythrocyte membrane.

    PubMed

    Gruber, H J

    1988-10-20

    In a previous paper we have reported on the structural perturbation of the erythrocyte membrane anion exchanger by a regular series of model amphiphiles, as shown by differential scanning calorimetry (Gruber, H.J. and Low, P.S., Biochim. Biophys. Acta, preceding article). Now the data are interpreted by a model in which the effects of amphiphile structure upon buffer-membrane partitioning are well separated from the dependence of the intrinsic potencies of membrane-bound amphiphiles upon amphiphile structure. The buffer-membrane partitioning situation was demonstrated to regularly change between extremes within a series of homologous amphiphiles, i.e. from a negligible to a predominant fraction of total amphiphile in the sample residing in the membrane. Based upon this demonstration a large number of reports on the chain length dependence of apparent potency could be reinterpreted in terms of chain length profiles of intrinsic potency, allowing for a comparison of the responses of various membrane proteins to homologous series of amphiphiles. The response patterns for chain length variation could be divided into three distinct classes: the intrinsic potency (i) can be independent of chain length over a very wide range of length, (ii) it can be rather independent up to a critical length where a sudden cut-off in potency occurs, or (iii) it can drop monotonically over a wide range of chain length. The intrinsic potency values of saturated fatty acids in destabilizing the anion exchanger were interpreted by very simple assumptions: only direct interactions between amphiphiles and target proteins and a simple amphiphile partition equilibrium between a pool of equivalent low affinity sites on the protein and the bulk lipid matrix. The observed monotonic decay of the intrinsic potency of saturated fatty acids with increasing chain length from C8 to C20 was translated into a constant increment of free energy by which each additional CH2 favors the transfer away from sites

  5. Mixed-mode isolation of triazine metabolites from soil and aquifer sediments using automated solid-phase extraction

    USGS Publications Warehouse

    Mills, M.S.; Thurman, E.M.

    1992-01-01

    Reversed-phase isolation and ion-exchange purification were combined in the automated solid-phase extraction of two polar s-triazine metabolites, 2-amino-4-chloro-6-(isopropylamino)-s-triazine (deethylatrazine) and 2-amino-4-chloro-6-(ethylamino)-s-triazine (deisopropylatrazine) from clay-loam and slit-loam soils and sandy aquifer sediments. First, methanol/ water (4/1, v/v) soil extracts were transferred to an automated workstation following evaporation of the methanol phase for the rapid reversed-phase isolation of the metabolites on an octadecylresin (C18). The retention of the triazine metabolites on C18 decreased substantially when trace methanol concentrations (1%) remained. Furthermore, the retention on C18 increased with decreasing aqueous solubility and increasing alkyl-chain length of the metabolites and parent herbicides, indicating a reversed-phase interaction. The analytes were eluted with ethyl acetate, which left much of the soil organic-matter impurities on the resin. Second, the small-volume organic eluate was purified on an anion-exchange resin (0.5 mL/min) to extract the remaining soil pigments that could foul the ion source of the GC/MS system. Recoveries of the analytes were 75%, using deuterated atrazine as a surrogate, and were comparable to recoveries by soxhlet extraction. The detection limit was 0.1 ??g/kg with a coefficient of variation of 15%. The ease and efficiency of this automated method makes it viable, practical technique for studying triazine metabolites in the environment.

  6. Impact of ozonation, anion exchange resin and UV/H2O2 pre-treatments to control fouling of ultrafiltration membrane for drinking water treatment.

    PubMed

    Pramanik, Biplob Kumar; Pramanik, Sagor Kumar; Sarker, Dipok Chandra; Suja, Fatihah

    2016-09-20

    The effects of ozonation, anion exchange resin (AER) and UV/H2O2 were investigated as a pre-treatment to control organic fouling (OF) of ultrafiltration membrane in the treatment of drinking water. It was found that high molecular weight (MW) organics such as protein and polysaccharide substances were majorly responsible for reversible fouling which contributed to 90% of total fouling. The decline rate increased with successive filtration cycles due to deposition of protein content over time. All pre-treatment could reduce the foulants of a Ultrafiltration membrane which contributed to the improvement in flux, and there was a greater improvement of flux by UV/H2O2 (61%) than ozonation (43%) which in turn was greater than AER (23%) treatment. This was likely due to the effective removal/breakdown of high MW organic content. AER gave greater removal of biofouling potential components (such as biodegradable dissolved organic carbon and assimilable organic carbon contents) compared to UV/H2O2 and ozonation treatment. Overall, this study demonstrated the potential of pre-treatments for reducing OF of ultrafiltration for the treatment of drinking water.

  7. High-performance anion-exchange chromatography coupled with diode array detection for the determination of dencichine in Panax notoginseng and related species.

    PubMed

    Qiao, Chun-Feng; Liu, Xiao-Mei; Cui, Xiu-Ming; Hu, De-Jun; Chen, Yi-Wen; Zhao, Jing; Li, Shao-Ping

    2013-08-01

    A high-performance anion-exchange chromatography coupled with diode array detection method was developed for the determination of dencichine in Panax notoginseng and related species. The analysis was performed on an Eprogen Synchropak WAX column (4.6 × 250 mm, 6 μm) with 50 mM NaH2 PO4 aqueous solution isocratic elution. The method was validated in terms of linearity, sensitivity, precision, stability, and accuracy. It was found that the calibration curve for dencichine showed good linearity (R(2) = 0.9999) within the test range. The LOD and LOQ were 0.77 and 3.06 ng, respectively. The RSD for intra- and interday repeatability was 0.2 and 0.5%, respectively. The test solution of dencichine is stable at least for three days at room temperature and for seven days at 4 °C. The mean recovery of dencichine was 102.0%. The established method was successfully applied to determine dencichine in the raw root of P. nogoginseng, P. ginseng, and P. quinquefolium as well as the steamed root of P. notoginseng. Compared with previous reports, this method is sensitive, selective, and accurate, which is helpful to evaluate the quality of P. notoginseng and related species.

  8. Anion exchange reaction potentials as approximate estimates of the relative thermodynamic stabilities of Mg/Al layered double hydroxides containing different anions.

    PubMed

    Prasad, Belavalli E; Kamath, P Vishnu; Vijayamohanan, K

    2011-11-15

    Coatings of hydrotalcite-like nitrate-intercalated Mg/Al layered double hydroxides are electrochemically deposited on a Pt electrode by electrogeneration of base by reduction of a mixed metal nitrate aqueous solution. As-prepared coatings are stable to workup and function as rugged electrodes. The voltammetric response generated by anion exchange of intercalated nitrate for dissolved anions from solution under equilibrium conditions is employed to estimate the thermodynamic stabilities of the Mg/Al layered double hydroxides comprising different anions relative to the nitrate-containing phase. Among monovalent anions, the most stable is the fluoride-containing LDH (ΔG° = -48.7 kJ mol(-1)) relative to the nitrate-containing LDH. The stability in aqueous phase decreases as F(-) > Cl(-) > Br(-) > NO(2)(-) > NO(3)(-), whereas, among divalent anions, SO(4)(2-) (ΔG° = -8.7 kJ mol(-1)) > CO(3)(2-) (ΔG° = 14.3 kJ mol(-1)). The results of monovalent ions match well with the Miyata series, whereas the divalent anion series is at variance with the commonly held belief that carbonate-LDHs are more stable than sulfate-LDHs.

  9. Anion-directed assemblies of cationic metal-organic frameworks based on 4,4'-bis(1,2,4-triazole): syntheses, structures, luminescent and anion exchange properties.

    PubMed

    Li, Xinxiong; Gong, Yaqiong; Zhao, Huaixia; Wang, Ruihu

    2014-11-17

    Three cationic metal-organic frameworks (MOFs), Ag(btr)·PF6·0.5CH3CN (1), Ag2(btr)2(H2O)·2CF3SO3·H2O (2), and Ag2(btr)2(NO3)·NO3 (3), were prepared from reaction of 4,4'-bis(1,2,4-triazole) (btr) with silver salts containing different anions. Complex 1 is a three-dimensional (3-D) framework constructed from tetrahedral-shaped nanoscale coordination cages with PF6(-) as counteranions. 2 and 3 are 3-D architectures containing 1-D channels, in which charge-balancing CF3SO3(-) and NO3(-) are located in their respective channels. Luminescent emission of 1-3 shows an obvious red shift compared with the btr ligand. Anion exchange studies show that 1 is able to selectively exchange MnO4(-) in aqueous solution with a modest capacity of 0.56 mol mol(-1); the luminescent emission of 1 is quickly quenched upon MnO4(-) exchange.

  10. Study of kinetic and fixed bed operation of removal of sulfate anions from an industrial wastewater by an anion exchange resin.

    PubMed

    Haghsheno, Reza; Mohebbi, Ali; Hashemipour, Hassan; Sarrafi, Amir

    2009-07-30

    Sulfate anions represent very important wastewater pollutants, which appear in the effluents discharged from copper mines. In this study, for the first time, an attempt has been made on the removal of sulfate anions by an ion exchange resin. This work is focused on the removal of sulfate anions from the Sarcheshmeh copper complex (Kerman province, Southeast of Iran) wastewater by an anion exchange resin. Batch experiments of sulfate anions adsorption on Lewatit K6362 resin were carried out to determine the adsorption equilibrium data and the relation of adsorption isotherms. Isothermal data can be fitted with Freundlich adsorption isotherms better than Langmuir equation. The results show that maximum removal of sulfate anions take places in the resin dosage of 1000 mg/100ml and the adsorption of sulfate anions on the resin follows reversible first-order kinetics. The overall adsorption rate constants were compared for different initial concentrations. Finally, the effects of parameters such as the flow rate, bed height and inlet adsorbate concentration on the breakthrough curve in a fixed bed column were studied in detail.

  11. Imidazolium-Based Porous Organic Polymers: Anion Exchange-Driven Capture and Luminescent Probe of Cr2O7(2.).

    PubMed

    Su, Yanqing; Wang, Yangxin; Li, Xiaoju; Li, Xinxiong; Wang, Ruihu

    2016-07-27

    A series of imidazolium-based porous organic polymers (POP-Ims) was synthesized through Yamamoto reaction of 1,3-bis(4-bromophenyl)imidazolium bromide and tetrakis(4-bromophenyl)ethylene. Porosities and hydrophilicity of such polymers may be well tuned by varying the ratios of two monomers. POP-Im with the highest density of imidazolium moiety (POP-Im1) exhibits the best dispersity in water and the highest efficiency in removing Cr2O7(2-). The capture capacity of 171.99 mg g(-1) and the removal efficiency of 87.9% were achieved using an equivalent amount of POP-Im1 within 5 min. However, no Cr2O7(2-) capture was observed using nonionic analogue despite its large surface area and abundant pores, suggesting that anion exchange is the driving force for the removal of Cr2O7(2-). POP-Im1 also displays excellent enrichment ability and remarkable selectivity in capturing Cr2O7(2-). Cr(VI) in acid electroplating wastewater can be removed completely using excess POP-Im1. In addition, POP-Im1 can serve as a luminescent probe for Cr2O7(2-) due to the incorporation of luminescent tetraphenylethene moiety.

  12. Preparing alkaline anion exchange membrane with enhanced hydroxide conductivity via blending imidazolium-functionalized and sulfonated poly(ether ether ketone)

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Jiang, Zhongyi; Tian, Huimin; Wang, Siwen; Zhang, Bei; Cao, Ying; He, Guangwei; Li, Zongyu; Wu, Hong

    2015-08-01

    The development of alkaline anion exchange membrane (AEM) with both high ion conductivity and stabilities is of great significance for fuel cell applications. In this study, a facile acid-base blending method is designed to improve AEM performances. Basic imidazolium-functionalized poly (ether ether ketone) with a high functionalization degree is employed as polymer matrix to pursue high ion-exchange capacity (IEC) as well as high hydroxide conductivity, meanwhile acidic sulfonated poly (ether ether ketone) (SPEEK) is employed as the cross-linking agent to enhance the stabilities of the blend membranes. Particularly, an in-situ Menshutkin/crosslinking method is exploited to prevent the flocculation in the preparation process of blend membranes. As a result, dense and defect-free blend membranes are obtained. The blend membranes exhibit high level of IEC up to 3.15 mmol g-1, and consequently possess elevated hydroxide conductivity up to 31.59 mS cm-1 at 30 °C. In addition, benefiting from the strong electrostatic interaction introduced by the acid-base blending, the stabilities and methanol resistance of blend membranes are enhanced.

  13. Analytical Method for Sugar Profile in Pet Food and Animal Feeds by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection.

    PubMed

    Ellingson, David J; Anderson, Phillip; Berg, Daniel P

    2016-01-01

    There is a need for a standardized, accurate, rugged, and consistent method to measure for sugars in pet foods and animal feeds. Many traditional standard sugar methods exist for other matrixes, but when applied in collaborative studies there was poor agreement and sources of error identified with those standard methods. The advancement in technology over the years has given us the ability to improve on these standard methods of analysis. A method is described here that addresses these common issues and was subjected to a single-laboratory validation to assess performance on a wide variety of pet foods and animal feeds. Of key importance to the method performance is the sample preparation before extraction, type of extraction solvent, postextraction cleanup, and, finally, optimized chromatography using high-performance anion exchange chromatography with pulsed amperometric detection. The results obtained from the validation demonstrate how typical issues seen with these matrixes can influence performance of sugar analysis. The results also demonstrate that this method is fit-for-purpose and can meet the challenges of sugar analysis in pet food and animal feeds to lay the foundation for a standardized method of analysis.

  14. Short-column anion-exchange chromatography for soil and peat humic substances profiling by step-wise gradient of high pH aqueous sodium ethylenediaminetetraacetate.

    PubMed

    Hutta, Milan; Ráczová, Janka; Góra, Róbert; Pessl, Juraj

    2015-08-21

    Novel anion-exchange liquid chromatographic method with step gradient of aqueous EDTA(4-) based mobile phase elution has been developed to profile available Slovak soil humic substances and alkaline extracts of various soils. The method utilize short glass column (30mm×3mm) filled in with hydrolytically stable particles (60μm diameter) Separon HEMA-BIO 1000 having (diethylamino)ethyl functional groups. Step gradient was programmed by mixing mobile phase composed of aqueous solution of sodium EDTA (pH 12.0; 5mmolL(-1)) and mobile phase constituted of aqueous solution of sodium EDTA (pH 12.0, 500mmolL(-1)). The FLD of HSs was set to excitation wavelength 480nm and emission wavelength 530nm (λem). Separation mechanism was studied by use of selected aromatic acids related to humic acids with the aid of UV spectrophotometric detection at 280nm. The proposed method benefits from high ionic strength (I=5molL(-1)) of the end mobile phase buffer and provides high recovery of humic acids (98%). Accurate and reproducible profiling of studied humic substances, alkaline extracts of various types of soils enables straightforward characterization and differentiation of HSs in arable and forest soils. Selected model aromatic acids were used for separation mechanism elucidation.

  15. Simultaneous analysis of acetaminophen, p-aminophenol and aspirin metabolites by hydrophilic interaction and strong anion exchange capillary liquid chromatography coupled to amperometric detection.

    PubMed

    Zheng, Minmin; Wu, Yimin; Lu, Lanxiang; Ding, Kang; Tang, Fengxiang; Lin, Zian; Wu, Xiaoping

    2011-08-01

    A simple and sensitive method has been developed for the simultaneous determination of polar nonsteroidal pharmaceuticals and metabolites, including acetaminophen, p-aminophenol and several aspirin metabolites (salicylic acid, gentisic acid, salicyluric acid and 2,3-dihydroxybenzoic acid), by capillary liquid chromatography with amperometric detection. Using a capillary monolithic column with mixed mode stationary phases and a mobile phase composed of acetonitrile and Tris buffer, rapid separation of six polar analytes was achieved within 8 min, and a hydrophilic interaction and strong anion exchange separation mechanism were exhibited. Method detection limits of six analytes ranged from 10 to 50 ng/mL. In terms of precision, the intra- and interday relative standard deviation values in all analytes never exceeded 3.1% for migration time and 8.9% for peak areas, respectively. This method provided a simple, rapid and cost-effective approach for the analysis of polar pharmaceuticals. The applicability of the method in pharmacokinetics was verified by spiking human serum samples with the compounds and analyzing the recoveries.

  16. A Pd/C-CeO2 Anode Catalyst for High-Performance Platinum-Free Anion Exchange Membrane Fuel Cells.

    PubMed

    Miller, Hamish A; Lavacchi, Alessandro; Vizza, Francesco; Marelli, Marcello; Di Benedetto, Francesco; D'Acapito, Francesco; Paska, Yair; Page, Miles; Dekel, Dario R

    2016-05-10

    One of the biggest obstacles to the dissemination of fuel cells is their cost, a large part of which is due to platinum (Pt) electrocatalysts. Complete removal of Pt is a difficult if not impossible task for proton exchange membrane fuel cells (PEM-FCs). The anion exchange membrane fuel cell (AEM-FC) has long been proposed as a solution as non-Pt metals may be employed. Despite this, few examples of Pt-free AEM-FCs have been demonstrated with modest power output. The main obstacle preventing the realization of a high power density Pt-free AEM-FC is sluggish hydrogen oxidation (HOR) kinetics of the anode catalyst. Here we describe a Pt-free AEM-FC that employs a mixed carbon-CeO2 supported palladium (Pd) anode catalyst that exhibits enhanced kinetics for the HOR. AEM-FC tests run on dry H2 and pure air show peak power densities of more than 500 mW cm(-2) .

  17. Overview of the effect of salts on biphasic ionic liquid/water solvent extraction systems: anion exchange, mutual solubility, and thermomorphic properties.

    PubMed

    Dupont, David; Depuydt, Daphne; Binnemans, Koen

    2015-06-04

    Hydrophobic (water-immiscible) ionic liquids (ILs) are frequently used as organic phase in solvent extraction studies. These biphasic IL/water extraction systems often also contain metal salts or mineral acids, which can significantly affect the IL trough (un)wanted anion exchange and changes in the solubility of IL in the aqueous phase. In the case of thermomorphic systems, variations in the cloud point temperature are also observed. All these effects have important repercussions on the choice of IL, suitable for a certain extraction system. In this paper, a complete overview of the implications of metal salts on biphasic IL/water systems is given. Using the Hofmeister series as a starting point, a range of intuitive prediction models are introduced, supported by experimental evidence for several hydrophobic ILs, relevant to solvent extraction. Particular emphasis is placed on the IL betainium bis(trifluoromethylsulfonyl)imide [Hbet][Tf2N]. The aim of this work is to provide a comprehensive interpretation of the observed effects of metal salts, so that it can be used to predict the effect on any given biphasic IL/water system instead of relying on case-by-case reports. These prediction tools for the impact of metal salts can be useful to optimize IL synthesis procedures, extraction systems and thermomorphic properties. Some new insights are also provided for the rational design of ILs with UCST or LCST behavior based on the choice of IL anion.

  18. Development of a novel, sensitive amperometric-FIA glucose biosensor by packing up the amperometric cell with glucose oxidase modified anion exchange resin.

    PubMed

    Su, Yuhua; Huang, Weixiong; Hu, Rongzong; Ding, Haodong; Hu, Kangkang

    2009-04-15

    In this work, the anion exchange resin (AER) was modified with a layer of glucose oxidase (GOD) and poly(diallyldimethylammonium chloride) (PDDA), respectively, via layer-by-layer electrostatic self-assembling strategy. The PDDA and GOD modified AER (PDDA/GOD/AER) was then packed into a home-made amperometric cell for flow injection analysis (FIA) of glucose. This design simplified the setup by integrating the enzyme reactor into the amperometric cell. And the AER in the cell behaved bifunctional, it was not only the support of enzymes, but also an anti-interference tool due to its retention effect toward ascorbic acid (AA) and uric acid (UA). A platinum modified porous titanium (Pt/PTi) electrode was utilized in the cell as the working electrode (WE), due to its large effective surface area it could increase the response by 8.3 times as compared with the planar pure platinum electrode. The proposed biosensor was very sensitive (22.4 microA cm(-2) mM(-1)) in glucose quantification, and the linear range was from 1 micromol L(-1) to 2 mmol L(-1) with the detection limit of 0.8 micromol L(-1). The biosensor was used for serum glucose determination, and the result obtained was satisfying. This work may have provided a reference design of the amperometric cell which could be adopted in other enzymatic-FIA biosensors.

  19. Anion exchange membrane prepared from simultaneous polymerization and quaternization of 4-vinyl pyridine for non-aqueous vanadium redox flow battery applications

    NASA Astrophysics Data System (ADS)

    Maurya, Sandip; Shin, Sung-Hee; Sung, Ki-Won; Moon, Seung-Hyeon

    2014-06-01

    A simple, single step and environmentally friendly process is developed for the synthesis of anion exchange membrane (AEM) by simultaneous polymerization and quaternization, unlike the conventional membrane synthesis which consists of separate polymerization and quaternization step. The membrane synthesis is carried out by dissolving polyvinyl chloride (PVC) in cyclohexanone along with 4-vinyl pyridine (4VP) and 1,4-dibromobutane (DBB) in the presence of thermal initiator benzoyl peroxide, followed by film casting to get thin and flexible AEMs. The membrane properties such as ion exchange capacity, ionic conductivity and swelling behaviour are tuned by varying the degree of crosslinking. These AEMs exhibit low vanadium permeability, while retaining good dimensional and chemical stability in an electrolyte solution, making them appropriate candidates for non-aqueous vanadium acetylacetonate redox flow battery (VRFB) applications. The optimized membrane displays ion exchange capacity and ionic conductivity of 2.0 mequiv g-1 and 0.105 mS cm-1, respectively, whereas the efficiency of 91.7%, 95.7% and 87.7% for coulombic, voltage and energy parameter in non-aqueous VRFB, respectively. This study reveals that the non-aqueous VRFB performance is greatly influenced by membrane properties; therefore the optimal control over the membrane properties is advantageous for the improved performance.

  20. Synthesis and characterizations of anion exchange organic-inorganic hybrid materials based on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)

    SciTech Connect

    Zhang Shaoling; Wu Cuiming; Xu Tongwen . E-mail: twxu@ustc.edu.cn; Gong Ming; Xu Xiaolong

    2005-07-15

    A series of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based organic-inorganic hybrid materials for anion exchange were prepared through sol-gel process of polymer precursors PPO-Si(OCH{sub 3}){sub 3}. PPO-Si(OCH{sub 3}){sub 3} were obtained from the reaction of bromomethylated PPO with 3-aminopropyl-trimethoxysilane (A1110). These polymer precursors then underwent hydrolysis and condensation with additional A1110 to generate hybrid materials. The reaction to produce polymer precursors was identified by FTIR; while FTIR, TGA, XRD, SEM, as well as conventional ion exchange capacity (IEC) measurements were conducted for the structures and properties of the prepared hybrids. TGA results show that this series of hybrid materials possess high thermal stability; XRD and SEM indicate that the prepared hybrid materials are amorphous and the inorganic and organic contents show good compatibility if the ratio between them is proper. The IEC values of the hybrid materials due to the amine groups range from 1.13 mmol/gBPPO (material i) to 4.80 mmol/gBPPO (material iv)

  1. Kinetic study of the concentration dependence of the mass transfer rate coefficient in anion-exchange chromatography of bovine serum albumin

    SciTech Connect

    Miyabe, Kanji; Guiochon, G. |

    1999-07-01

    The experimental results of a previous study of the mass transfer kinetics of bovine serum albumin (BSA) in ion-exchange chromatography under nonlinear conditions are reevaluated. The analysis of the concentration dependence of the lumped mass-transfer rate coefficient (k{sub m,L}) provides information on the kinetics of axial dispersion, fluid-to-particle mass transfer, intraparticle mass transfer, and adsorption/desorption. The new analysis shows that the contribution of intraparticle mass transfer is the dominant one. Similar to k{sub m,L}, the surface diffusivity (D{sub s}) of BSA increases with increasing concentration. The linear concentration dependence of k{sub m,L} seems to originate in a similar dependence of D{sub s}. The use of a heterogeneous-surface model for the anion-exchange resin provides an explanation of the positive concentration dependence of D{sub s}. This work illustrates how frontal analysis data can be used for a detailed investigation of the kinetics of mass transfer between the phases of a chromatographic column, in addition to its conventional use in the determination of the thermodynamic characteristics of the phase equilibrium.

  2. Investigation of gamma radiation effect on the anion exchange resin Amberlite IRA-400 in hydroxide form by Fourier transformed infrared and 13C nuclear magnetic resonance spectroscopies.

    PubMed

    Traboulsi, A; Dupuy, N; Rebufa, C; Sergent, M; Labed, V

    2012-03-02

    Radiation-induced decomposition of the anion exchange resin Amberlite IRA-400 in hydroxide form by gamma radiolysis has been studied under different irradiation doses and irradiation atmospheres. In this work, we focused on the degradation of the solid part of the resin by Fourier transformed infrared (FTIR) and (13)C nuclear magnetic resonance (NMR) spectroscopies associated with chemometric treatments. FTIR and (13)C NMR techniques showed that only -CH(2)N(+)(CH(3))(3) groups were detached from the resin whereas the polystyrene divinylbenzene backbone remains intact. The quaternary ammonium groups were replaced by amine or carbonyl groups according to the irradiation atmosphere (with or without water or oxygen). Principal components analysis (PCA) was used to classify the degraded resins according to their irradiation conditions by separating the effect of the dose or the environment. The PCA loadings have shown spectral regions which discriminate the irradiated resins whereas SIMPLe-to-use Interactive Self-modeling Mixture Analysis (SIMPLISMA) allows to identify families of component characterizing the chemical structure of resins and estimate their relative contributions according to the irradiation atmospheres.

  3. On-line anion exchange solid-phase extraction coupled to liquid chromatography with fluorescence detection to determine quinolones in water and human urine.

    PubMed

    Lara, Francisco J; Del Olmo-Iruela, Monsalud; García-Campaña, Ana M

    2013-10-04

    An analytical method based on on-line solid-phase extraction coupled to liquid chromatography with fluorescence detection has been developed to determine quinolones in tap water and human urine. A home-made setup was used to percolate 10 mL of sample through a solid-phase extraction column. Analytes were retained onto the sorbent by an anion exchange mechanism which ensures an optimum compatibility with the subsequent chromatographic separation. A C-18 column containing core-shell particles (2.6 μm) was used to achieve peak efficiencies up to 200,000 plates/m, at a flow rate of 1.2 mL/min and without the need for special pumps. The method allowed the determination of 11 quinolones directly in tap water samples in less than 20 min and with limits of detection ranging between 7 and 110 ng/L. The sensitivity achieved made possible the direct determination of 9 quinolones in human urine without any sample treatment, just dilution with water. Relative recoveries between 94 and 109% were obtained meaning that the matrix effect in human urine is negligible after dilution. Satisfactory results were also obtained in terms of precision since relative standard deviations were always below 13%.

  4. Preparation of quaternary amine monolithic column for strong anion-exchange chromatography and its application to the separation of Enterovirus 71.

    PubMed

    Gu, Huimin; Yin, Dezhong; Ren, Jie; Zhang, Baoliang; Zhang, Qiuyu

    2016-10-15

    Large size virion is unable to diffuse into pores of conventional porous chromatography particles. Therefore, separation of virion by conventional column-packing materials is not quite efficient. To solve this problem, a monolithic column with large convective pores and quaternary amine groups was prepared and was applied to separate Enterovirus 71 (EV71, ≈5700-6000kDa). Cross-section, pore structure, hydrodynamic performance, adsorption property and dynamic binding capacity of prepared monolithic column were determined. Double-pore structures, macropore at 2472nm and mesopore at 5-60nm, were formed. The porosity was up to 63.3%, which enable higher permeability and lower back pressure of the monolithic column than commercial UNO™ Q1 column. Based on the breakthrough curves, the loading capacity of bovine serum albumin was calculated to be 42.0mg per column. In addition, prepared quaternary amine monolithic column was proved to be suitable for the separation of protein mixture by strong anion-exchange chromatography. As a practical application, prepared monolith column presents excellent performance to the separation of EV71 from virus-proteins mixture.

  5. Partially hydrolyzed guar gum characterization and sensitive quantification in food matrices by high performance anion exchange chromatography with pulsed amperometric detection--validation using accuracy profile.

    PubMed

    Mercier, G; Campargue, C

    2012-11-02

    Interest concerning functional ingredients and especially dietary fibres has been growing in recent years. At the same time, the variety of ingredient accepted as dietary fibres and their mixing at low level in complex matrices have considerably complicated their quantitative analysis by approved AOAC methods. These reasons have led to the specific development of an innovative analytical method performed by high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection (PAD) to detect and quantify partially hydrolyzed guar gum (PHGG) in fruit preparation and dairy matrices. The analytical methodology was divided in two steps which could be deployed separately or in conjunction. The first, consists in a complete characterization of PHGG by size exclusion chromatography (SEC) with multi-angle light scattering and refractive index detection and HPAEC-PAD to determine its physico-chemical properties and galactomannans content, and the second step is the development of a new HPAEC-PAD method for PHGG direct quantification in complex matrices (dairy product). Validation in terms of detection and quantification limits, linearity of the analytical range, average accuracy (recovery, trueness) and average uncertainty were statistically carried out with accuracy profile. Overall, this new chromatographic method has considerably improved the possibility to quantify without fractionation treatment, low level of dietary fibres emerging from specific galactomannans, in complex matrices and many foodstuffs.

  6. Monosaccharide composition of sweetpotato fiber and cell wall polysaccharides from sweetpotato, cassava, and potato analyzed by the high-performance anion exchange chromatography with pulsed amperometric detection method.

    PubMed

    Salvador, L D; Suganuma, T; Kitahara, K; Tanoue, H; Ichiki, M

    2000-08-01

    The cell wall materials (CWMs) from sweetpotato (Ipomoea batatas cv. Kokei 14), cassava (Manihot esculenta), and potato (Solanum tuberosum cv. Danshaku) and commercial sweetpotato fiber as well as their polysaccharide fractions were analyzed for sugar composition by the high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) method. The separation of arabinose and rhamnose, and xylose and mannose, by this method has been improved using a CarboPac PA 10 column. Pretreatment of the CWMs and cellulose fractions with 12 M H(2)SO(4) was required for complete hydrolysis to occur. Commercial sweetpotato fiber was found to be mainly composed of glucose (88.4%), but small amounts of other sugars were also detected. Among the root crops, sweetpotato CWM had the highest amount of pectin and galacturonic acid. Fucose was detected only in cassava CWM and its hemicellulose fraction, while galactose was present in the highest amount in potato CWM. Among the polysaccharide fractions, it was only in the hemicellulose fraction where significant differences in the sugar composition, especially in the galactose content, were observed among the root crops.

  7. The effects of ionizing radiation on Reillex trademark HPQ, a new macroporous polyvinylpyridine resin, and on four conventional polystyrene anion exchange resins

    SciTech Connect

    Marsh, S.F.

    1990-11-01

    This study compares the effects of ionizing radiation on Reillex{trademark} HPQ, a recently available macroporous copolymer of 1-methyl-4-vinylpyridine/divinylbenzene, and on four conventional strong-base polystyrene anion exchange resins. The polystyrene resins investigated included one gel type, Dowex{trademark} 1 {times} 4, and three macroporous resins: Dow{trademark} MSA-1, Amberlite{trademark} IRA-900, and Lewatit{trademark} MP-500-FK. Each resin, in 7 M nitric acid, was subjected to seven different levels of {sup 60}Co gamma radiation ranging from 100 to 1000 megarads. Irradiated resins were measured for changes in dry weight, wet volume, chloride and Pu(IV) exchange capacities, and thermal stability. In separate experiments, each resin was subjected to approximately 340 megarads of in situ alpha particles from sorbed plutonium. Resin damage from alpha particles was less than half that caused by gamma rays, which may be a consequence of different production rates of radiolytic nitrite and nitro radicals in the two systems. Reillex{trademark} HPQ resin provided the greatest radiation stability, whereas Lewatit{trademark} MP-500-FK was the least stable of the resins tested. Thermogravimetric analyses of dry, nitrate-form resin revealed that dry Reillex{trademark} HPQ resin offered the best thermal stability for absorbed gamma doses to 370 megarads, but the worst thermal stability after exposures of 550 megarads or more. 25 refs., 11 figs., 13 tabs.

  8. Anion-exchange engineering of cookie-like Bi2S3/Bi2MoO6 heterostructure for enhanced photocatalytic activities and gas-sensing properties.

    PubMed

    Pei, Yu; Li, Xiaoguang; Chu, Hang; Ge, Yuancai; Dong, Pei; Baines, Robert; Pei, Liyuan; Ye, Mingxin; Shen, Jianfeng

    2017-04-01

    Developing efficient visible-light-driven photocatalysts will advance alternative energy technologies, ultimately curbing the environmental pollution associated with fossil fuels. In this work, Bi2S3/Bi2MoO6 photocatalysts with a heterogeneous cookie-like structure were prepared for the first time by in-situ anion exchange at relatively low temperatures. The catalysts exhibited enhanced photocatalytic activity, which we attributed to the photocurrent response, a diminished recombination rate of photogenerated electron-hole pairs, and the existence of a large heterojunction interface. These governing factors were discerned by photoelectrochemical measurements, calculated energy band positions and photoluminescence spectra. Bi2S3/Bi2MoO6 nanocomposites also exhibit better performance in response to gas than bare Bi2MoO6 according to gas sensing tests. Our work, in relaying a feasible method to synthesize Bi2S3/Bi2MoO6-based heterojunction superstructures, and documents a universal preparation method of synthetic heterogeneous complexes, and provides necessary groundwork for the development of next generation semiconductor photocatalytic technology and gas sensor.

  9. Durability and performance of polystyrene- b -poly(vinylbenzyl trimethylammonium) diblock copolymer and equivalent blend anion exchange membranes

    SciTech Connect

    Vandiver, Melissa A.; Caire, Benjamin R.; Poskin, Zach; Li, Yifan; Seifert, Sönke; Knauss, Daniel M.; Herring, Andrew M.; Liberatore, Matthew W.

    2014-11-01

    Anion exchange membranes (AEM) are solid polymer electrolytes that facilitate ion transport in fuel cells. In this study, a polystyrene-b-poly(vinylbenzyl trimethylammonium) diblock copolymer was evaluated as potential AEM and compared with the equivalent homopolymer blend. The diblock had a 92% conversion of reactive sites with an IEC of 1.72 ± 0.05 mmol g-1, while the blend had a 43% conversion for an IEC of 0.80 ± 0.03 mmol g-1. At 50°C and 95% relative humidity, the chloride conductivity of the diblock was higher, 24–33 mS cm-1, compared with the blend, 1–6 mS cm-1. The diblock displayed phase separation on the length scale of 100 nm, while the blend displayed microphase separation (~10 μm). Mechanical characterization of films from 40 to 90 microns thick found that elasticity and elongation decreased with the addition of cations to the films. At humidified conditions, water acted as a plasticizer to increase film elasticity and elongation. While the polystyrene-based diblock displayed sufficient ionic conductivity, the films' mechanical properties require improvement, i.e., greater elasticity and strength, before use in fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41596.

  10. Interplay between water uptake, ion interactions, and conductivity in an e-beam grafted poly(ethylene-co-tetrafluoroethylene) anion exchange membrane

    SciTech Connect

    Pandey, Tara P.; Maes, Ashley M.; Sarode, Himanshu N.; Peters, Bethanne D.; Lavina, Sandra; Vezzù, Keti; Yang, Yuan; Poynton, Simon D.; Varcoe, John R.; Seifert, Soenke; Liberatore, Matthew W.; Di Noto, Vito; Herring, Andrew M.

    2014-12-23

    We demonstrate that the true hydroxide conductivity in an e-beam grafted poly(ethylene-co-tetrafluoroethylene) [ETFE] anion exchange membrane (AEM) is as high as 132 mS cm-1 at 80 °C and 95% RH, comparable to a proton exchange membrane, but with very much less water present in the film. To understand this behaviour we studied ion transport of hydroxide, carbonate, bicarbonate and chloride, as well as water uptake and distribution. Water uptake of the AEM in water vapor is an order of magnitude lower than when submerged in liquid water. In addition 19F pulse field gradient spin echo NMR indicates that there is little tortuosity in the ionic pathways through the film. A complete analysis of the IR spectrum of the AEM and the analyses of water absorption using FT-IR led to conclusion that the fluorinated backbone chains do not interact with water and that two types of water domains exist within the membrane. The reduction in conductivity was measured during exposure of the OH- form of the AEM to air at 95% RH and was seen to be much slower than the reaction of CO2 with OH- as the amount of water in the film determines its ionic conductivity and at relative wet RHs its re-organization is slow.

  11. Interplay between water uptake, ion interactions, and conductivity in an e-beam grafted poly(ethylene-co-tetrafluoroethylene) anion exchange membrane

    DOE PAGES

    Pandey, Tara P.; Maes, Ashley M.; Sarode, Himanshu N.; ...

    2014-12-23

    We demonstrate that the true hydroxide conductivity in an e-beam grafted poly(ethylene-co-tetrafluoroethylene) [ETFE] anion exchange membrane (AEM) is as high as 132 mS cm-1 at 80 °C and 95% RH, comparable to a proton exchange membrane, but with very much less water present in the film. To understand this behaviour we studied ion transport of hydroxide, carbonate, bicarbonate and chloride, as well as water uptake and distribution. Water uptake of the AEM in water vapor is an order of magnitude lower than when submerged in liquid water. In addition 19F pulse field gradient spin echo NMR indicates that there ismore » little tortuosity in the ionic pathways through the film. A complete analysis of the IR spectrum of the AEM and the analyses of water absorption using FT-IR led to conclusion that the fluorinated backbone chains do not interact with water and that two types of water domains exist within the membrane. The reduction in conductivity was measured during exposure of the OH- form of the AEM to air at 95% RH and was seen to be much slower than the reaction of CO2 with OH- as the amount of water in the film determines its ionic conductivity and at relative wet RHs its re-organization is slow.« less

  12. Application of the shock layer theory to the determination of the mass transfer rate coefficient and its concentration dependence for proteins on anion exchange columns

    SciTech Connect

    Sajonz, P. ||; Guan-Sajonz, H.; Zhong, G.; Guiochon, G. |

    1997-03-01

    The extension of the shock layer theory to systems having a slow mass transfer kinetics and a concentration-dependent rate coefficient is discussed. Experiments were carried out with bovine serum albumin on two anion exchanges, TSK-GEL-DEAE-5PW and Resource-Q. The adsorption isotherm data, determined by single-step frontal analysis, could be fitted to simplified bi-Langmuir equations with vary small residuals. A lumped kinetic model (solid film linear driving force model, with rate coefficient k{sub f}) was used to account for the mass transfer kinetics. The profile of each breakthrough curve (BC) was fitted to the curve calculated with this transport model and the rate coefficient k{sub f} obtained by identification. A linear dependence of k{sub f} on the average concentration of the step of the BC was found. The shock layer thicknesses (SLT) calculated for different relative concentrations agreed very well with the experimental results. This justifies the use of the SLT for the direct determination of rate coefficients. 19 refs., 9 figs., 2 tabs.

  13. Modeling, rate-limiting step investigation, and enhancement of the direct bio-regeneration of perchlorate laden anion-exchange resin.

    PubMed

    Wang, Chao; Lippincott, Lee; Yoon, In-Ho; Meng, Xiaoguang

    2009-01-01

    Anion-exchange with high perchlorate affinity resins is one of the most promising technologies for removing low levels of perchlorate. However, the traditional brine desorption technique is difficult and costly for regeneration of this type of resin. Previously, a direct bio-regeneration method by contacting the spent high perchlorate affinity resin with the perchlorate-reducing bacteria was proved feasible. This research is a further study of that method. Firstly, a direct bio-regeneration process model, based on the physicochemical and biological fundamentals, was developed and calibrated with experimental data. Thereafter, the rate-limiting step in regeneration of the high perchlorate affinity resin was investigated. Methods to enhance the regeneration efficiency were developed. The results indicated that the calibrated model well described the regeneration process. It thus might provide useful insights into the regeneration system. The results also demonstrated that the perchlorate desorption from the loaded resin could be the rate-limiting step. Addition of proper amount of counter anions such as chloride and sulfate improved the regeneration efficiency because these anions could promote both the extent and rate of perchlorate desorption from the loaded resin. These findings aided us in achieving good and efficient regeneration of high perchlorate affinity resins like the A-530E and SR-7 resins. The findings also suggested that the application of bacteria that could efficiently reduce perchlorate in highly saline solution would make the method more promising for the regeneration of high perchlorate affinity resins.

  14. Determination of U isotope ratios in sediments using ICP-QMS after sample cleanup with anion-exchange and extraction chromatography.

    PubMed

    Zheng, Jian; Yamada, Masatoshi

    2006-01-15

    The determination of uranium is important for environmental radioactivity monitoring, which investigates the releases of uranium from nuclear facilities and of naturally occurring radioactive materials by the coal, oil, natural gas, mineral, ore refining and phosphate fertilizer industries, and it is also important for studies on the biogeochemical behavior of uranium in the environment. In this paper, we describe a quadrupole ICP-MS (ICP-QMS)-based analytical procedure for the accurate determination of U isotope ratios ((235)U/(238)U atom ratio and (234)U/(238)U activity ratio) in sediment samples. A two-stage sample cleanup using anion-exchange and TEVA extraction chromatography was employed in order to obtain accurate and precise (234)U/(238)U activity ratios. The factors that affect the accuracy and precision of U isotope ratio analysis, such as detector dead time, abundance sensitivity, dwell time and mass bias were carefully evaluated and corrected. With natural U, a precision lower than 0.5% R.S.D. for (235)U/(238)U atom ratio and lower than 2.0% R.S.D. for (234)U/(238)U activity ratio was obtained with less than 90 ng uranium. The developed analytical method was validated using an ocean sediment reference material and applied to an investigation into the uranium isotopic compositions in a sediment core in a brackish lake in the vicinity of U-related nuclear facilities in Japan.

  15. X-ray Lithography on Perovskite Nanocrystals Films: From Patterning with Anion-Exchange Reactions to Enhanced Stability in Air and Water

    PubMed Central

    2015-01-01

    Films of colloidal CsPbX3 (X = I, Br or Cl) nanocrystals, prepared by solution drop-casting or spin-coating on a silicon substrate, were exposed to a low flux of X-rays from an X-ray photoelectron spectrometer source, causing intermolecular C=C bonding of the organic ligands that coat the surface of the nanocrystals. This transformation of the ligand shell resulted in a greater stability of the film, which translated into the following features: (i) Insolubility of the exposed regions in organic solvents which caused instead complete dissolution of the unexposed regions. This enabled the fabrication of stable and strongly fluorescent patterns over millimeter scale areas. (ii) Inhibition of the irradiated regions toward halide anion exchange reactions, when the films were exposed either to halide anions in solution or to hydrohalic vapors. This feature was exploited to create patterned regions of different CsPbIxBryClz compositions, starting from a film with homogeneous CsPbX3 composition. (iii) Resistance of the films to degradation caused by exposure to air and moisture, which represents one of the major drawbacks for the integration of these materials in devices. (iv) Stability of the film in water and biological buffer, which can open interesting perspectives for applications of halide perovskite nanocrystals in aqueous environments. PMID:26617344

  16. Ion distribution in quaternary-ammonium-functionalized aromatic polymers: effects on the ionic clustering and conductivity of anion-exchange membranes.

    PubMed

    Weiber, E Annika; Jannasch, Patric

    2014-09-01

    A series of copoly(arylene ether sulfone)s that have precisely two, three, or four quaternary ammonium (QA) groups clustered directly on single phenylene rings along the backbone are studied as anion-exchange membranes. The copolymers are synthesized by condensation polymerizations that involve either di-, tri-, or tetramethylhydroquinone followed by virtually complete benzylic bromination using N-bromosuccinimide and quaternization with trimethylamine. This synthetic strategy allows excellent control and systematic variation of the local density and distribution of QA groups along the backbone. Small-angle X-ray scattering of these copolymers shows extensive ionic clustering, promoted by an increasing density of QA on the single phenylene rings. At an ion-exchange capacity (IEC) of 2.1 meq g(-1), the water uptake decreases with the increasing local density of QA groups. Moreover, at moderate IECs at 20 °C, the Br(-) conductivity of the densely functionalized copolymers is higher than a corresponding randomly functionalized polymer, despite the significantly higher water uptake of the latter. Thus, the location of multiple cations on single aromatic rings in the polymers facilitates the formation of a distinct percolating hydrophilic phase domain with a high ionic concentration to promote efficient anion transport, despite probable limitations by reduced ion dissociation. These findings imply a viable strategy to improve the performance of alkaline membrane fuel cells.

  17. Analysis of nonstructural carbohydrates in storage organs of 30 ornamental geophytes by high-performance anion-exchange chromatography with pulsed amperometric detection.

    PubMed

    Ranwala, Anil P; Miller, William B

    2008-01-01

    A comprehensive analysis of nonstructural carbohydrates in storage organs (bulbs and corms) of 30 ornamental geophytes was conducted by employing a variety of extraction techniques followed by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD). Among species, starch, fructan, glucomannan and soluble sugars accounted for 50-80% of storage organ dry weight (DW). Starch ranged from 24 to 760 mg g(-1) DW, fructan (commonly occurring with starch) from 25 to 500 mg g(-1) DW, and glucomannan from 15 to 145 mg g(-1) DW. An acid hydrolysis protocol for concurrent determination of fructan and glucomannan was developed. The average degree of polymerization (DP) of ethanol and water-soluble fructan and the man : glu ratio of glucomannan also varied between species. The 80% ethanol fraction contained soluble sugars and short-chain fructans (< 25 DP), whereas water extracts contained soluble sugars, fructans (both short- and long-chain,

  18. Assembly of graphene and nickel nanoparticles on anion exchange resin microspheres for the amperometric detection of carbohydrates in combination with capillary electrophoresis.

    PubMed

    Zhang, Ren; Lu, Sijie; Zhang, Luyan; Chen, Gang

    2014-12-29

    Graphene and nickel nanoparticles (NiNPs) were assembled on anion exchange resin (AER) microspheres based on the electrostatic interaction between graphene oxide sheets and AER and the subsequent chemical reduction. The prepared AER@graphene-NiNP composite core-shell microspheres were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Moreover, they were embedded in the bores of pipette tips to fabricate electrodes. The performance of the novel electrodes was demonstrated by measuring sucrose, glucose and fructose in combination with capillary electrophoresis. The three analytes were well separated within 8min in a 40cm long capillary at a separation voltage of 12kV. The graphene-NiNP composite microsphere electrodes exhibited higher sensitivity (213.578-317.064nAmM(-1)), lower detection limits (0.75-1.05μM) and enhanced separation efficiency in the detection of these carbohydrates. The advantages of the electrodes include ease of fabrication, low cost and pronounced electrocatalytic activity toward carbohydrates, indicating great promise for a wide range of applications.

  19. Advanced treatment of textile dyeing secondary effluent using magnetic anion exchange resin and its effect on organic fouling in subsequent RO membrane.

    PubMed

    Yang, Cheng; Li, Li; Shi, Jialu; Long, Chao; Li, Aimin

    2015-03-02

    Strict regulations are forcing dyeing factory to upgrade existing waste treatment system. In this study, advanced treatment of dyeing secondary effluent by magnetic anion exchange resin (NDMP) was investigated and compared with ultrafiltration (UF); NDMP as a pre-treatment of reverse osmosis (RO) was also studied. NDMP resin (20 mL/L) gave higher removal of dissolved organic carbon (DOC) (83.9%) and colority (94.9%) than UF with a cut-off of 10 kDa (only 48.6% and 44.1%, respectively), showing that NDMP treatment was effective to meet the stringent discharge limit of DOC and colority. Besides, NDMP resin (20 mL/L) as a pretreatment of RO increased the permeate flux by 12.5% and reduced irreversible membrane fouling by 6.6%, but UF pretreatment did not mitigate RO membrane fouling. The results of excitation-emission matrix fluorescence spectra and resin fractions showed that NDMP had more efficient removal than UF for transphilic acid and hydrophilic fraction, such as protein-like organic matters and soluble microbial products, which contributed to a significant proportion of RO membrane fouling. In sum, NDMP resin treatment not only gave effective removal of DOC and colority of dyeing secondary effluent, but exhibited some improvement for RO membrane flux and irreversible fouling.

  20. Novel quaternary ammonium microblock poly (p-phenylene-co-aryl ether ketone)s as anion exchange membranes for alkaline fuel cells

    NASA Astrophysics Data System (ADS)

    Dong, Xue; Xue, Boxin; Qian, Huidong; Zheng, Jifu; Li, Shenghai; Zhang, Suobo

    2017-02-01

    Using cation compounds as raw materials, three quaternized microblock poly(p-phenylene-co-aryl ether ketone)s (s-, m-, and l-QPP-co-PAEK) were synthesized using a nickel (0)-catalyzed coupling reaction. Hydrophilic and hydrophobic moieties were affixed using cationic quaternary ammonium (QA) groups attached to poly(p-phenylene) by a three-carbon interstitial spacer and nonionic dichloride monomers of various lengths, respectively. The morphology, water uptake, swelling ratio, mechanical properties, thermal stability, hydroxide conductivity and alkaline stability of these new membranes were investigated. Experimental results indicated that the membrane with the longest hydrophobic microblock exhibited high hydroxide conductivity (37.6 mS cm-1 at 80 °C) resulting from the aggregation of ionic clusters observed using TEM. The copolymers with longer hydrophobic nonionic segments exhibited improved alkaline stability, suggesting that the hydrophobic chain shields the QA groups and that the polymer chains pack in a manner that restricts rotation. Controlling the distribution of QA groups in poly(p-phenylene) moieties and tuning the block length of nonionic segments are demonstrated to be effective methods for improving the hydroxide conductivity and alkaline stability of anion exchange membranes.

  1. Improving the separation of Cu(II) from Zn(II) based on an anion exchanger for the preparation a 62Zn/62Cu generator.

    PubMed

    El-Azony, K M

    2011-09-01

    A separation procedure of (64,67)Cu(II) from (65)Zn(II) was studied for serving (62)Zn/(62)Cu generator preparation. The distribution coefficients of (65)Zn(II) and (64,67)Cu(II) ions from homogeneous medium of hydrochloric acid and acetone onto De-Acidite FF anion exchanger were investigated. Both hydrochloric acid and acetone concentrations are important factors that affect the separation process. Effects of decreasing the HCl concentration from 0.2 to 0.04 M, increasing the acetone concentration from 5% to 80% and different acetone concentrations (5-97%) in 0.2M HCl were also studied on the separation of (64,67)Cu(II) from (65)Zn(II). The exchange capacity of Zn(II) on the De-Acidite FF matrix was obtained as 3.8 meq/g and the(64,67)Cu(II) elution efficiency was 92.5% using 20 ml of 0.2M HCl-60% acetone with flow rate of 2 ml/min.The radionuclidic purity and radiochemical purity of the eluted (64,67)Cu(II) were examined.

  2. Imidazolium-Functionalized Poly(arylene ether sulfone) Anion-Exchange Membranes Densely Grafted with Flexible Side Chains for Fuel Cells.

    PubMed

    Guo, Dong; Lai, Ao Nan; Lin, Chen Xiao; Zhang, Qiu Gen; Zhu, Ai Mei; Liu, Qing Lin

    2016-09-28

    With the intention of optimizing the performance of anion-exchange membranes (AEMs), a set of imidazolium-functionalized poly(arylene ether sulfone)s with densely distributed long flexible aliphatic side chains were synthesized. The membranes made from the as-synthesized polymers are robust, transparent, and endowed with microphase segregation capability. The ionic exchange capacity (IEC), hydroxide conductivity, water uptake, thermal stability, and alkaline resistance of the AEMs were evaluated in detail for fuel cell applications. Morphological observation with the use of atomic force microscopy and small-angle X-ray scattering reveals that the combination of high-local-density-type and side-chain-type architectures induces distinguished nanophase separation in the AEMs. The as-prepared membranes have advantages in effective water management and ionic conductivity over traditional main-chain polymers. Typically, the conductivity and IEC were in the ranges of 57.3-112.5 mS cm(-1) and 1.35-1.84 mequiv g(-1) at 80 °C, respectively. Furthermore, the membranes exhibit good thermal and alkaline stability and achieve a peak power density of 114.5 mW cm(-2) at a current density of 250.1 mA cm(-2). Therefore, the present polymers containing clustered flexible pendent aliphatic imidazolium promise to be attractive AEM materials for fuel cells.

  3. Survey of inorganic arsenic in marine animals and marine certified reference materials by anion exchange high-performance liquid chromatography-inductively coupled plasma mass spectrometry.

    PubMed

    Sloth, Jens J; Larsen, Erik H; Julshamn, Kåre

    2005-07-27

    A method for the determination of inorganic arsenic in seafood samples using high-performance liquid chromatography-inductively coupled plasma mass spectrometry is described. The principle of the method relied on microwave-assisted alkaline dissolution of the sample, which at the same time oxidized arsenite [As(III)] to arsenate [As(V)], whereby inorganic arsenic could be determined as the single species As(V). Anion exchange chromatography using isocratic elution with aqueous ammonium carbonate as the mobile phase was used for the separation of As(V) from other coextracted organoarsenic compounds, including arsenobetaine. The stability of organoarsenic compounds during the sample pretreatment was investigated, and no degradation/conversion to inorganic arsenic was detected. The method was employed for the determination of inorganic arsenic in a variety of seafood samples including fish, crustaceans, bivalves, and marine mammals as well as a range of marine certified reference materials, and the results were compared to values published in the literature. For fish and marine mammals, the results were in most cases below the limit of detection. For other sample types, inorganic arsenic concentrations up to 0.060 mg kg(-)(1) were found. In all samples, the inorganic arsenic content constituted less than 1% of the total arsenic content.

  4. Short communication: Quantification of carbohydrates in whey permeate products using high-performance anion-exchange chromatography with pulsed amperometric detection.

    PubMed

    Lee, Hyeyoung; de MeloSilva, Vitor Luiz; Liu, Yan; Barile, Daniela

    2015-11-01

    A method was developed for the characterization and quantification of the disaccharide lactose and 3 major bovine milk oligosaccharides (BMO) in dairy streams. Based on high-performance anion-exchange chromatography-pulsed amperometric detection (HPAE-PAD), this method is advantageous because it requires minimal sample preparation and achieves good chromatographic separation of oligosaccharide isomers within 30min. The linear dynamic range and limit of detection were 0.1 to 10mg/L and 0.03 to 0.22mg/L, respectively. Mean recoveries of the BMO were excellent and ranged from 98.4 to 100.4%. Without complicated sample preparation procedures, this HPAE-PAD method measured BMO [3'-sialyllactose (3'SL), 6'-sialyllactose (6'SL), and 6'-sialyllactosamine (6'SLN)] and lactose using a single instrument, therefore increasing the accuracy of the measurement and applicability for the dairy industry. In colostrum whey permeate, 3'SL, 6'SL, and 6'SLN were 94, 29, and 46mg/L, respectively. This work is the first to demonstrate that some commercial products, currently marketed for supporting a healthy immune system, contain significant amounts of bioactive BMO and therefore, carry additional bioactivities.

  5. Anion-Exchange Induced Strong π-π Interactions in Single Crystalline Naphthalene Diimide for Nitroexplosive Sensing: An Electronic Prototype for Visual on-Site Detection.

    PubMed

    Kalita, Anamika; Hussain, Sameer; Malik, Akhtar Hussain; Barman, Ujjwol; Goswami, Namami; Iyer, Parameswar Krishnan

    2016-09-28

    A new derivative of naphthalene diimide (NDMI) was synthesized that displayed optical, electrical, and visual changes exclusively for the most widespread nitroexplosive and highly water-soluble toxicant picric acid (PA) due to strong π-π interactions, dipole-charge interaction, and a favorable ground state electron transfer process facilitated by Coulombic attraction. The sensing mechanism and interaction between NDMI with PA is demonstrated via X-ray diffraction analysis, (1)H NMR studies, cyclic voltammetry, UV-visible/fluorescence spectroscopy, and lifetime measurements. Single crystal X-ray structure of NDMI revealed the formation of self-assembled crystalline network assisted by noncovalent C-H···I interactions that get disrupted upon introducing PA as a result of anion exchange and strong π-π stacking between NDMI and PA. Morphological studies of NDMI displayed large numbers of single crystalline microrods along with some three-dimensional (3D) daisy-like structures which were fabricated on Al-coated glass substrate to construct a low-cost two terminal sensor device for realizing vapor mode detection of PA at room temperature and under ambient conditions. Furthermore, an economical and portable electronic prototype was developed for visual and on-site detection of PA vapors under exceptionally realistic conditions.

  6. PDLIM5 links kidney anion exchanger 1 (kAE1) to ILK and is required for membrane targeting of kAE1

    PubMed Central

    Su, Ya; Hiemstra, Thomas F.; Yan, Yahui; Li, Juan; Karet, Hannah I.; Rosen, Lawrence; Moreno, Pablo; Frankl, Fiona E. Karet

    2017-01-01

    Anion exchanger 1 (AE1) mediates Cl−/HCO3− exchange in erythrocytes and kidney intercalated cells where it functions to maintain normal bodily acid-base homeostasis. AE1’s C-terminal tail (AE1C) contains multiple potential membrane targeting/retention determinants, including a predicted PDZ binding motif, which are critical for its normal membrane residency. Here we identify PDLIM5 as a direct binding partner for AE1 in human kidney, via PDLIM5’s PDZ domain and the PDZ binding motif in AE1C. Kidney AE1 (kAE1), PDLIM5 and integrin-linked kinase (ILK) form a multiprotein complex in which PDLIM5 provides a bridge between ILK and AE1C. Depletion of PDLIM5 resulted in significant reduction in kAE1 at the cell membrane, whereas over-expression of kAE1 was accompanied by increased PDLIM5 levels, underscoring the functional importance of PDLIM5 for proper kAE1 membrane residency, as a crucial linker between kAE1 and actin cytoskeleton-associated proteins in polarized cells. PMID:28045035

  7. Analysis of crude heparin by (1)H NMR, capillary electrophoresis, and strong-anion-exchange-HPLC for contamination by over sulfated chondroitin sulfate.

    PubMed

    Keire, David A; Trehy, Michael L; Reepmeyer, John C; Kolinski, Richard E; Ye, Wei; Dunn, Jamie; Westenberger, Benjamin J; Buhse, Lucinda F

    2010-03-11

    We previously published a strong-anion-exchange-high performance liquid chromatography (SAX-HPLC) method for the detection of the contaminant over sulfated chondroitin sulfate (OSCS) in heparin sodium active pharmaceutical ingredient (API). While APIs have been processed to remove impurities, crude heparins contain insoluble material, chondroitin sulfates, heparan sulfate, and proteins that may interfere with the recovery and measurement of OSCS. We examined 500MHz (1)H NMR, capillary electrophoresis (CE), and SAX-HPLC to quantify OSCS in crude heparin. Using our standard API protocol on OSCS spiked crude heparin samples; we observed a weight percent LOD and LOQ for the NMR approach of 0.1% and 0.3%, respectively, while the SAX-HPLC method gave values of 0.03% and 0.09%, respectively. CE data was not amenable to quantitative measurement of OSCS in crude heparin. We developed a modified HPLC sample preparation protocol using crude dissolved at the 100mg/mL level with a 2.5M NaCl solution. This SAX-HPLC approach gave a weight percent LOD of 0.02% and a LOQ of 0.07% and had better performance characteristics than that of the protocol used for APIs.

  8. Studies of removal of platinum(IV) ion microquantities from the model solutions of aluminium, copper, iron, nickel and zinc chloride macroquantities on the anion exchanger Duolite S 37.

    PubMed

    Hubicki, Z; Wójcik, G

    2006-08-25

    Platinum has been widely applied in catalytic industry and the recovery of noble metals from industrial wastes becomes an economic issue. The laboratory studies of platinum(IV) microquantities removal from 1M aluminium, copper, iron, nickel and zinc chloride solutions in 0.1M hydrochloric acid solutions on the anion exchanger Duolite S 37 of the functional secondary and tertiary amine groups were carried out. For this anion exchanger the fraction extracted values (%E, Pt(IV)) as well as the sorption isotherms were determined depending on the kind of aqueous phase and phase contact time. Moreover, the bed and weight distribution coefficients as well as working and total ion-exchange capacities were calculated from the platinum(IV) breakthrough curves. Kinetic parameters were determined.

  9. A combination of ion exchange and electrochemical reduction for nitrate removal from drinking water. Part I: nitrate removal using a selective anion exchanger in the bicarbonate form with reuse of the regenerant solution.

    PubMed

    Jelínek, Ludek; Parschová, Helena; Matejka, Zdenek; Paidar, Martin; Bouzek, Karel

    2004-01-01

    The process of selective nitrate removal from drinking water by means of ion exchange was studied. A commercial strong base anion exchanger with triethylammonium (-N+Et3) functional groups was used in the bicarbonate (HCO3-) and carbonate (CO3(2-)) form. The aim of this study was to optimize ion-exchanger regeneration in view of the subsequent electrochemical reduction of nitrates in the spent regenerant solution. The effects of ion-exchanger form, concentration of regenerant solution, and presence of nitrates, chlorides, and sulphates in the regenerant solution were studied. The strong base anion exchanger in HCO3- form that was investigated was able to treat 270 bed volumes of model water solution containing 124 mg dm(-3) nitrates. To achieve adequate regeneration of the saturated anion exchanger, it is necessary to use approximately 30 bed volumes of fresh 1-M sodium bicarbonate (NaHCO3) regenerant solution. The presence of residual 50-mg dm(-3) nitrates in the regenerant solution, treated by electrolysis, resulted in an increase in the dose of regenerant solution to 35 bed volumes and a decrease in the subsequent sorption run of approximately 13%. The volume of applied regenerant solution was high, but the consumption of NaHCO3 for regeneration was low.

  10. Solvent-extraction purification of neptunium

    SciTech Connect

    Kyser, E.A.; Hudlow, S.L.

    2008-07-01

    The Savannah River Site (SRS) has recovered {sup 237}Np from reactor fuel that is currently being processed into NpO{sub 2} for future production of {sup 238}Pu. Several purification flowsheets have been utilized. An oxidizing solvent-extraction (SX) flowsheet was used to remove Fe, sulfate ion, and Th while simultaneously {sup 237}Np, {sup 238}Pu, u, and nonradioactive Ce(IV) was extracted into the tributyl phosphate (TBP) based organic solvent. A reducing SX flowsheet (second pass) removed the Ce and Pu and recovered both Np and U. The oxidizing flowsheet was necessary for solutions that contained excessive amounts of sulfate ion. Anion exchange was used to perform final purification of Np from Pu, U, and various non-actinide impurities. The Np(IV) in the purified solution was then oxalate-precipitated and calcined to an oxide for shipment to other facilities for storage and future target fabrication. Performance details of the SX purification and process difficulties are discussed. (authors)

  11. Ethanol precipitation for purification of recombinant antibodies.

    PubMed

    Tscheliessnig, Anne; Satzer, Peter; Hammerschmidt, Nikolaus; Schulz, Henk; Helk, Bernhard; Jungbauer, Alois

    2014-10-20

    Currently, the golden standard for the purification of recombinant humanized antibodies (rhAbs) from CHO cell culture is protein A chromatography. However, due to increasing rhAbs titers alternative methods have come into focus. A new strategy for purification of recombinant human antibodies from CHO cell culture supernatant based on cold ethanol precipitation (CEP) and CaCl2 precipitation has been developed. This method is based on the cold ethanol precipitation, the process used for purification of antibodies and other components from blood plasma. We proof the applicability of the developed process for four different antibodies resulting in similar yield and purity as a protein A chromatography based process. This process can be further improved using an anion-exchange chromatography in flowthrough mode e.g. a monolith as last step so that residual host cell protein is reduced to a minimum. Beside the ethanol based process, our data also suggest that ethanol could be replaced with methanol or isopropanol. The process is suited for continuous operation.

  12. Role of adaptor proteins and clathrin in the trafficking of human kidney anion exchanger 1 (kAE1) to the cell surface.

    PubMed

    Junking, Mutita; Sawasdee, Nunghathai; Duangtum, Natapol; Cheunsuchon, Boonyarit; Limjindaporn, Thawornchai; Yenchitsomanus, Pa-thai

    2014-07-01

    Kidney anion exchanger 1 (kAE1) plays an important role in acid-base homeostasis by mediating chloride/bicarbornate (Cl-/HCO3-) exchange at the basolateral membrane of α-intercalated cells in the distal nephron. Impaired intracellular trafficking of kAE1 caused by mutations of SLC4A1 encoding kAE1 results in kidney disease - distal renal tubular acidosis (dRTA). However, it is not known how the intracellular sorting and trafficking of kAE1 from trans-Golgi network (TGN) to the basolateral membrane occurs. Here, we studied the role of basolateral-related sorting proteins, including the mu1 subunit of adaptor protein (AP) complexes, clathrin and protein kinase D, on kAE1 trafficking in polarized and non-polarized kidney cells. By using RNA interference, co-immunoprecipitation, yellow fluorescent protein-based protein fragment complementation assays and immunofluorescence staining, we demonstrated that AP-1 mu1A, AP-3 mu1, AP-4 mu1 and clathrin (but not AP-1 mu1B, PKD1 or PKD2) play crucial roles in intracellular sorting and trafficking of kAE1. We also demonstrated colocalization of kAE1 and basolateral-related sorting proteins in human kidney tissues by double immunofluorescence staining. These findings indicate that AP-1 mu1A, AP-3 mu1, AP-4 mu1 and clathrin are required for kAE1 sorting and trafficking from TGN to the basolateral membrane of acid-secreting α-intercalated cells.

  13. Effect of long-term organic removal on ion exchange properties and performance during sewage tertiary treatment by conventional anion exchange resins.

    PubMed

    Sun, Jian; Li, Xiaofeng; Quan, Ying; Yin, Yunjun; Zheng, Shaokui

    2015-10-01

    This study evaluated the long-term dissolved organic matter (DOM), phosphorus and nitrogen removal performance of a commercially available conventional anion exchange resin (AER) from actual secondary effluent (SE) in a sewage treatment plant based on a pilot-scale operation (2.2 m(3) d(-1), 185 cycles, 37,000 bed volume, 1.5 years). Particular emphasis was given to the potential effect of DOM fouling on the ion exchange properties and performance during the long-term operation. Despite the large range of COD (15.6-33.5 mg L(-1)), BOD5 (3.0-5.6 mg L(-1)), DOC (6.5-24.2 mg L(-1)), and UV254 (UV absorption at 254 nm) (0.108-0.229 cm(-1)) levels in the SE, the removal efficiencies of the AER for the aforementioned parameters were 43±12%, 46±15%, 45±9%, and 72±4%, respectively. Based on three-dimensional fluorescence excitation-emission matrix data, i.e., the fluorescence intensities of four regions (peaks A-D), all organic components of the SE were effectively removed (peak A 74%, peak B 48%, peak C 55%, and peak D 45%) following the adsorption. The AER effluent still has considerable polycyclic aromatic hydrocarbons' ecological hazard on freshwater fishes when they were significantly removed from SE. The obvious DOM fouling on the AER, identified by color change, had no significant influence on the long-term removal of the representative inorganic anions (averaging 95±4% phosphate, 100±0% SO4(2-), and 62±17% NO3(-)) and AER properties (including total exchange capacity, moisture content, and true density). The conventional AER can produce high quality reclaimed water from SE at a low operational cost.

  14. Effects of the exchange capacity and cross-linking degree on the hydration states of anions in quantitative loading onto strongly basic anion-exchange resins.

    PubMed

    Yuchi, Akio; Kuroda, Shigeo; Takagi, Mayuu; Watanabe, Yuuya; Nakao, Satoshi

    2010-10-15

    The water content was determined for five strongly basic anion-exchange resins (trimethyammonium type having different exchange capacities and cross-linking degrees by divinylbenzene) in definite anionic forms (ten singly, three doubly, one triply, and one quadruply charged) dried at 25 °C and at a relative humidity of 50%. Incorporation of the results of the previous research on the conventional resins by X-ray absorption fine structure and diffraction methods indicated that the present method gave the number of intrinsic water molecules strongly interacting with an anion. The hydration numbers of weakly hydrating anions (Cl⁻, Br⁻, and ClO₄⁻) and a small anion (F⁻) were independent of the exchange capacity and slightly decreased with an increase in cross-linking, especially at 8%. The small and strongly hydrating ion F⁻ kept the in-water hydration structure to form a water-separated ion pair in the resins, while the other weakly hydrating ions were appreciably dehydrated to form a contact ion pair. The hydration number of a strongly hydrating ion, H₂PO₄⁻, appreciably decreased with increases in both the exchange capacity and cross-linking degree accompanied by intermolecular hydrogen bonding between the anions. This may be related to other characteristics of the H₂PO₄⁻ form resin, such as a higher concentration required for quantitative exchange, a systematic change in infrared spectra on the degree of exchange, and facile thermal dehydration, giving H₂P₂O₇²⁻. In contrast, multivalent anions were exchanged without dehydration, due to the larger space allowed for in the resins and the stronger interaction with water compared to those of monovalent anions.

  15. Integrated one-pot enrichment and immobilization of styrene monooxygenase (StyA) using SEPABEAD EC-EA and EC-Q1A anion-exchange carriers.

    PubMed

    Ruinatscha, Reto; Karande, Rohan; Buehler, Katja; Schmid, Andreas

    2011-07-18

    A straightforward one-pot procedure combining enrichment and immobilization of recombinantely expressed FADH₂ dependent styrene monooxygenase (StyA) directly from Escherichia coli cell extracts was investigated. Sepabeads EC-EA and EC-Q1A anion-exchange carriers were employed to non-covalently adsorb StyA from the cell extracts depending on basic parameters such as varying initial protein concentrations and pH. The protein fraction of the cell extract contained around 25% StyA. At low initial protein concentrations (2.5 mg mL⁻¹) and pH 6, the enzyme could be enriched up to 52.4% on Sepabeads EC-EA and up to 46.0% on Sepabeads EC-Q1A, accounting for an almost complete StyA adsorption from the cell extracts. Higher initial protein concentrations were necessary to exploit the high loading capacity of the beads. At 20 mg mL⁻¹, up to 37.6% of the theoretical bead loading capacity could be utilized for StyA binding using Sepabeads EC-EA, and 34.0% using Sepabeads EC-Q1A. For both carriers, protein leakage under reaction conditions could be reduced to less than 2%. During assays, the FADH₂ cofactor necessary for StyA activity was supplied by the NADH-FAD reductase component styrene monooxygenase B (StyB). StyA immobilized on Sepabeads EC-Q1A displayed twice as high styrene epoxidation rates (0.2 U mg(StyA)⁻¹) as compared to Sepabeads EC-EA. This activity could be increased to 0.7 U mg(StyA)⁻¹ by co-immobilizing StyB on Sepabeads EC-Q1A, which corresponds to 33% of the soluble StyA activity.

  16. A fabrication strategy for nanosized zero valent iron (nZVI)-polymeric anion exchanger composites with tunable structure for nitrate reduction.

    PubMed

    Jiang, Zhenmao; Zhang, Shujuan; Pan, Bingcai; Wang, Wenfeng; Wang, Xiaoshu; Lv, Lu; Zhang, Weiming; Zhang, Quanxing

    2012-09-30

    To reveal how the distribution of nanoscale zero-valent iron (nZVI) affect their reduction efficiency of its polymer-based composites and to further develop a simple strategy to tune the structure of the composites, we prepared four nZVI-polymerstyrene anion exchanger composites with similar nZVI loadings (13.5-14.4 Fe % in mass) but different distributions just through varying the concentration of NaBH(4) (0.9, 1.8, 3.6, and 7.2% in mass) solution during reduction of nZVI precursor (FeCl(4)(-) anions). As observed by SEM-EDX images, increasing the NaBH(4) concentration resulted in a more uniform nZVI distribution within the polymer, and thereto higher NH(4)(+)N production, faster reaction rate and more gaseous products during its reduction of nitrate and nitrite. nZVI distribution of the composites was suggested to greatly depend upon two processes, the hydrolyzation of anionic FeCl(4)(-) into cationic Fe(3+) and the reduction of both Fe(III) species by NaBH(4). Higher NaBH(4) concentration favored its faster diffusion into the inside polymer and in situ reduction of Fe(III) species into nZVI, causing a more uniform nZVI distribution. The results reported herein suggest that adjusting the NaBH(4) concentration was a simple and effective method to control the nZVI distribution in the supporting polymers, and indirectly tune the reactivity of the resultant nZVI hybrids.

  17. Improvements to in-line desalting of oligosaccharides separated by high-pH anion exchange chromatography with pulsed amperometric detection.

    PubMed

    Thayer, J R; Rohrer, J S; Avdalovic, N; Gearing, R P

    1998-02-15

    High-pH anion exchange chromatography with pulsed amperometric detection (HPAEC/PAD) (1) is routinely used to separate neutral and charged oligosaccharides differing by branch, linkage, and positional isomerism. Oligosaccharides are eluted in 0.1 M NaOH with gradients of sodium acetate (up to 0.25 M). Analyses of HPAEC/PAD-purified oligosaccharides generally require neutralization and removal of eluent salts. To facilitate the process, we designed and produced a cation-exchange system to remove sodium ions (Na+) from the eluent after oligosaccharide detection [the Carbohydrate Membrane Desalter (CMD), with a volatile regenerant]. Exchange of >99.5% of eluent Na+ for hydronium ions (H3O+) within the CMD generates dilute acetic acid (removable by vacuum evaporation). The exchange process desalts up to 0.35 M Na+ at 1.0 ml/min. Oligosaccharides collected after on-line desalting, evaporated and resuspended in their original volume of deionized water contained < or = 350 muM residual Na+ when the eluting sodium concentration was 300 mM. This represents a desalting efficiency of >99.8%. Recovery of neutral and sialylated oligosaccharides under these conditions ranged from 75 to 100%. With the CMD system and postcollection evaporation, HPAEC/PAD can purify oligosaccharides ready for further characterization. As a proof test, oligosaccharides from a human monoclonal antibody were separated by HPAEC/PAD, desalted with the CMD system, dried, and analyzed by matrix-assisted laser desorption-ionization, time-of-flight mass spectrometry.

  18. Use of strong anion exchange resins for the removal of perfluoroalkylated substances from contaminated drinking water in batch and continuous pilot plants.

    PubMed

    Zaggia, Alessandro; Conte, Lino; Falletti, Luigi; Fant, Massimo; Chiorboli, Andrea

    2016-03-15

    In recent years abnormally high levels of perfluoroalkylated substances (PFAS) have been detected both in surface and underground water sampled in an area covering approximately 150 square kilometers in the Veneto region (Italy) indicating the presence of a pollution point source (fluorochemicals production plant). Adsorption on granular activated carbon is an emergency measure which is poorly effective requiring frequent replacement. This work focuses on the application of three strong anion exchange resins (Purolite® A520E, A600E and A532E) for the removal of traces of PFOA, PFOS, PFBA and PFBS (concentration of hundreds of ng L(-1)) from drinking water. This technology is attractive for the possibility of reusing resins after an in-situ regeneration step. A strong relationship between the hydrophobicity of the exchange functional group of the resin and its capacity in removing PFAS exists. A600E (non hydrophobic) and A520E (fairly hydrophobic) show a reduced sorption capacity compared to A532E (highly hydrophobic). While A600E and A520E can be regenerated with solvent-less dilute solutions of non-toxic NH4Cl and NH4OH, A532E requires concentrated solutions of methanol or ethanol and 1% NH4Cl and for the sake of this work it was regarded as non-regenerable. The volume of regeneration effluents requiring incineration can be efficiently reduced by more than 96.5% by using reverse osmosis coupled with under-vacuum evaporation. Transmission electron analysis on saturated resins showed that large molecular macro-aggregates of PFAS can form in the intraparticle pores of resin indicating that ion exchange is not the only mechanism involved in PFAS removal.

  19. Determination of carbohydrates, sugar alcohols, and glycols in cell cultures and fermentation broths using high-performance anion-exchange chromatography with pulsed amperometric detection.

    PubMed

    Hanko, V P; Rohrer, J S

    2000-08-01

    Cell cultures and fermentation broths are complex mixtures of organic and inorganic compounds. Many of these compounds are synthesized or metabolized by microorganisms, and their concentrations can impact the yields of desired products. Carbohydrates serve as carbon sources for many microorganisms, while sugar alcohols (alditols), glycols (glycerol), and alcohols (methanol and ethanol) are metabolic products. We used high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD) to simultaneously analyze for carbohydrates, alditols, and glycerol in growing yeast (Saccharomyces cerevisiae) cultures and their final fermentation broths. Both cultures were grown on complex undefined media, aliquots centrifuged to remove particulates, and the supernatants diluted and directly injected for analysis. Pulsed amperometry allowed a direct detection of the carbohydrates, alditols, and glycols present in the cultures and fermentation broths with very little interference from other matrix components. The broad linear range of three to four orders of magnitude allowed samples to be analyzed without multiple dilutions. Peak area RSDs were 2-7% for 2, 3-butanediol, ethanol, glycerol, erythritol, rhamnose, arabitol, sorbitol, galactitol, mannitol, arabinose, glucose, galactose, lactose, ribose, raffinose, and maltose spiked into a heat-inactivated yeast culture broth supernatant that was analyzed repetitively for 48 h. This method is useful for directly monitoring culture changes during fermentation. The carbohydrates in yeast cultures were monitored over 1 day. A yeast culture with medium consisting primarily of glucose and trace levels of trehalose and arabinose showed a drop in sugar concentration over time and an increase in glycerol. Yeast growing on a modified culture medium consisting of multiple carbohydrates and alditols showed preference for specific carbon sources and showed the ability to regulate pathways leading to catalysis of

  20. The role of polymer nanolayer architecture on the separation performance of anion-exchange membrane adsorbers: part II. DNA and virus separations.

    PubMed

    Bhut, Bharat V; Weaver, Justin; Carter, Andrew R; Wickramasinghe, S Ranil; Husson, Scott M

    2011-11-01

    The surface-initiated polymerization protocol developed in part I was used to prepare strong anion-exchange membranes with variable polymer chain graft densities and degrees of polymerization for DNA and virus particle separations. A focus of part II was to evaluate the role of polymer nanolayer architecture on DNA and virus binding. Salmon sperm-DNA (SS-DNA) was used as model nucleic acid to measure the dynamic-binding capacities at 10% breakthrough. The dynamic-binding capacity increases linearly with increasing poly ([2-(methacryloyloxy)ethyl]trimethylammonium chloride) chain density up to the highest chain density used in this study. The new membranes yielded threefold higher SS-DNA-binding capacity (30 mg/mL) than a leading commercial membrane with the same functional group chemistry. Elution of bound DNA yielded a sharp peak, and resulted in a 13-fold increase relative to the feed concentration. This concentration effect further demonstrates the highly favorable transport properties of the newly designed Q-type membranes. However, unlike findings in part I on protein binding, SS-DNA binding was not fully reversible. Minute virus of mice (MVM) was used as model virus to evaluate the virus clearance performance of newly designed Q-type membranes. Log reduction of virus (LRV) of MVM increased with increasing polymer chain density. Membranes exhibited >4.5 LRV for the given MVM impurity load and may be capable of higher LRV values, as the MVM concentration in the flow-through fraction of these samples was below the limit of detection of the assay.

  1. Strong anion exchange liquid chromatographic separation of protein amino acids for natural 13C-abundance determination by isotope ratio mass spectrometry.

    PubMed

    Abaye, Daniel A; Morrison, Douglas J; Preston, Tom

    2011-02-15

    Amino acids are the building blocks of proteins and the analysis of their (13)C abundances is greatly simplified by the use of liquid chromatography (LC) systems coupled with isotope ratio mass spectrometry (IRMS) compared with gas chromatography (GC)-based methods. To date, various cation exchange chromatography columns have been employed for amino acid separation. Here, we report strong anion exchange chromatography (SAX) coupled to IRMS with a Liquiface interface for amino acid δ(13)C determination. Mixtures of underivatised amino acids (0.1-0.5 mM) and hydrolysates of representative proteins (prawns and bovine serum albumin) were resolved by LC/IRMS using a SAX column and inorganic eluents. Background inorganic carbon content was minimised through careful preparation of alkaline reagents and use of a pre-injector on-line carbonate removal device. SAX chromatography completely resolved 11 of the 16 expected protein amino acids following acid hydrolysis in underivatised form. Basic and neutral amino acids were resolved with 35 mM NaOH in isocratic mode. Elution of the aromatic and acidic amino acids required a higher hydroxide concentration (180 mM) and a counterion (NO 3-, 5-25 mM). The total run time was 70 min. The average δ(13)C precision of baseline-resolved peaks was 0.75‰ (range 0.04 to 1.06‰). SAX is a viable alternative to cation chromatography, especially where analysis of basic amino acids is important. The technology shows promise for (13)C amino acid analysis in ecology, archaeology, forensic science, nutrition and protein metabolism.

  2. Effects of the transport site conformation on the binding of external NAP-taurine to the human erythrocyte anion exchange system: evidence for intrinsic asymmetry

    SciTech Connect

    Knauf, P.A.; Law, F.Y.; Tarshis, T.; Furuya, W.

    1984-05-01

    External N-(4-azido (NAP-taurine) inhibits human red cell chloride exchange by binding to a site that is distinct from the chloride transport site. Increases in the intracellular chloride concentration (at constant external chloride) cause an increase in the inhibitory potency of external NAP-taurine. This effect is not due to the changes in pH or membrane potential that usually accompany a chloride gradient, since even when these changes are reversed or eliminated the inhibitory potency remains high. According to the ping-pong model for anion exchange, such transmembrane effects of intracellular chloride on external NAP-taurine can be explained if NAP-taurine only binds to its site when the transport site is in the outward-facing (E/sub o/ or ECl/sub o/) form. Since NAP-taurine prevents the conformational change from ECl/sub o/ to ECl/sub i/, it must lock the system in the outward-facing form. NAP-taurine can therefore be used just like the competitive inhibitor H/sub 2/DIDS (4,4'-diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid) to monitor the fraction of transport sites that face outward. A quantitative analysis of the effects of chloride gradients on the inhibitory potency of NAP-taurine and H/sub 2/DIDS reveals that the transport system is intrinsically asymmetric, such that when Cl/sub i/ = Cl/sub o/, most of the unloaded transport sites face the cytoplasmic side of the membrane. 30 references, 7 figures, 3 tables.

  3. New reversed phase-high performance liquid chromatographic method for selective separation of yttrium from all rare earth elements employing nitrilotriacetate complexes in anion exchange mode.

    PubMed

    Dybczyński, Rajmund S; Kulisa, Krzysztof; Pyszynska, Marta; Bojanowska-Czajka, Anna

    2015-03-20

    Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8-3.5, and post column derivatization with Arsenazo III, yttrium is eluted in the region of light REE, between Nd and Sm and is base line separated from Nd and Sm and even from promethium. Simple model employing literature data on complex formation of REE with NTA and based on anion exchange mechanism was developed to foresee the order of elution of individual REE. The model correctly predicted that lanthanides up to Tb will be eluted in the order of increasing Atomic Number (At.No.) but all heavier REE will show smaller retention factors than Tb. Concurrent UV/VIS detection at 658nm and the use of radioactive tracers together with γ-ray spectrometric measurements made possible to establish an unique elution order of elution of REE: La, Ce, Pr, Nd, Pm, Y, Sm, Er, Ho, Tm, Yb, Eu, Lu, Dy+Gd, Tb, Sc. The real place of Y however, in this elution series differs from that predicted by the model (Y between Sm and Eu). The method described in this work enables selective separation of Y from La, Ce, Pr, Nd, Pm, Sm and all heavier REE treated as a group.

  4. Determination of amino acids in cell culture and fermentation broth media using anion-exchange chromatography with integrated pulsed amperometric detection.

    PubMed

    Hanko, Valoran P; Rohrer, Jeffrey S

    2004-01-01

    Cell culture and fermentation broth media are used in the manufacture of biotherapeutics and many other biological materials. Characterizing the amino acid composition in cell culture and fermentation broth media is important because deficiencies in these nutrients can reduce desired yields or alter final product quality. Anion-exchange (AE) chromatography using sodium hydroxide (NaOH) and sodium acetate gradients, coupled with integrated pulsed amperometric detection (IPAD), determines amino acids without sample derivatization. AE-IPAD also detects carbohydrates, glycols, and sugar alcohols. The presence of these compounds, often at high concentrations in cell culture and fermentation broth media, can complicate amino acid determinations. To determine whether these samples can be analyzed without sample preparation, we studied the effects of altering and extending the initial NaOH eluent concentration on the retention of 42 different carbohydrates and related compounds, 30 amino acids and related compounds, and 3 additional compounds. We found that carbohydrate retention is impacted in a manner different from that of amino acid retention by a change in [NaOH]. We used this selectivity difference to design amino acid determinations of diluted cell culture and fermentation broth media, including Bacto yeast extract-peptone-dextrose (yeast culture medium) broth, Luria-Bertani (bacterial culture medium) broth, and minimal essential medium and serum-free protein-free hybridoma medium (mammalian cell culture media). These media were selected as representatives for both prokaryotic and eukaryotic culture systems capable of challenging the analytical technique presented in this paper. Glucose up to 10mM (0.2%, w/w) did not interfere with the chromatography, or decrease recovery greater than 20%, for the common amino acids arginine, lysine, alanine, threonine, glycine, valine, serine, proline, isoleucine, leucine, methionine, histidine, phenylalanine, glutamate, aspartate

  5. Automated purification of Borrelia burgdorferi s.l. PCR products with KingFisher™ magnetic particle processor prior to genome sequencing

    NASA Astrophysics Data System (ADS)

    Mäkinen, Johanna; Marttila, Harri; Viljanen, Matti K.

    2001-01-01

    Borrelia burgdorferi sensu lato genospecies were differentiated by PCR-based sequencing of the borrelial flagellin gene. To evaluate the usefulness of KingFisher™ magnetic particle processor in PCR product purification, borrelia PCR products were purified with KingFisher™ magnetic particle processor prior to cycle sequencing and the quality of the sequence data received was analyzed. KingFisher was found to offer a rapid and reliable alternative for borrelial PCR product purification.

  6. Isolation and purification of monosialotetrahexosylgangliosides from pig brain by extraction and liquid chromatography.

    PubMed

    Bian, Liujiao; Yang, Jianting; Sun, Yu

    2015-10-01

    Monosialotetrahexosylganglioside (GM1), one of glycosphingolipids containing sialic acid, plays particularly important role in fighting against paralysis, dementia and other diseases caused by brain and nerve damage. In this work, a simple and highly efficient method with high yield was developed for isolation and purification of GM1 from pig brain. The method consisted of an extraction by chloroform-methanol-water and a two-step chromatographic separation by DEAE-Sepharose Fast Flow anion-exchange medium and Sephacryl S-100 HR size-exclusion medium. The purified GM1 was proved to be homogeneous and had a purity of >98.0% by high-performance anion-exchange and size-exclusion chromatography. The molecular weight was 30.0 kDa by high-performance size-exclusion chromatography and 1546.9 Da by electrospray ionization mass spectrometry. The chromogenic reaction by resorcinol-hydrochloric acid solution indicated that the purified GM1 showed a specific chromogenic reaction of sialic acid. Through this isolation and purification program, ~1.0 mg of pure GM1 could be captured from 500 g wet pig brain tissue and the yield of GM1 was around 0.022%, which was higher than the yields by other methods. The method may provide an alternative for isolation and purification of GM1 in other biological tissues.

  7. Studies on separation and purification of fission (99)Mo from neutron activated uranium aluminum alloy.

    PubMed

    Rao, Ankita; Kumar Sharma, Abhishek; Kumar, Pradeep; Charyulu, M M; Tomar, B S; Ramakumar, K L

    2014-07-01

    A new method has been developed for separation and purification of fission (99)Mo from neutron activated uranium-aluminum alloy. Alkali dissolution of the irradiated target (100mg) results in aluminum along with (99)Mo and a few fission products passing into solution, while most of the fission products, activation products and uranium remain undissolved. Subsequent purification steps involve precipitation of aluminum as Al(OH)3, iodine as AgI/AgIO3 and molybdenum as Mo-α-benzoin oxime. Ruthenium is separated by volatilization as RuO4 and final purification of (99)Mo was carried out using anion exchange method. The radiochemical yield of fission (99)Mo was found to be >80% and the purity of the product was in conformity with the international pharmacopoeia standards.

  8. Automated Water-Purification System

    NASA Technical Reports Server (NTRS)

    Ahlstrom, Harlow G.; Hames, Peter S.; Menninger, Fredrick J.

    1988-01-01

    Reverse-osmosis system operates and maintains itself with minimal human attention, using programmable controller. In purifier, membranes surround hollow cores through which clean product water flows out of reverse-osmosis unit. No chemical reactions or phase changes involved. Reject water, in which dissolved solids concentrated, emerges from outer membrane material on same side water entered. Flow controls maintain ratio of 50 percent product water and 50 percent reject water. Membranes expected to last from 3 to 15 years.

  9. The purification and properties of ferritin from human serum.

    PubMed Central

    Worwood, M; Dawkins, S; Wagstaff, M; Jacobs, A

    1976-01-01

    1. Ferritin has been isolated from the serum of four patients with iron overload by using two methods. 2. In method A, the serum was adjusted to pH 4.8 and heated to 70 degr