Convection-aided collection of metal ions using chelating porous flat-sheet membranes

Chelating porous membranes were prepared by radiation-induced graft polymerization of an epoxy-group-containing monomer onto a polyethylene flat sheet and subsequent conversion of the epoxy group to an iminodiacetate group as a chelate-forming group. The chelating group density on the resultant porous flat-sheet membrane of 1.0 mol/kg was comparable to that of commercially available chelating beads. The pure water permeability of the membrane was 40% that of the trunk porous membrane, which was used for microfiltration. During the permeation of a copper chloride solution through the membrane, diffusional mass-transfer resistance of copper ion was negligible, since the ion was transported by convective flow through the pore. The tensile strength and elongation at break of the membranes were measured as a function of dose of electron-beam irradiation, the degree of grafting, and the chelating group density to determine an applicable range for practical use.     

Separation of U and Pu in spent nuclear fuel sample using anion-exchange-group-introduced porous polymer sheet for ICP-MS determination

Anion-exchange porous sheets were prepared by radiation-induced graft polymerization and subsequent chemical modifications. A diethylamino (DEA) group as an anion-exchange group was introduced into the polymer chain grafted onto a porous sheet. The DEA group-introduced porous sheet was cut into disks 13 mm in diameter and 3 mm in thickness to fit an empty cylindrical cartridge (DEA cartridge). The DEA sheet had a DEA group of 3.4 mol/kg of the DEA-group-containing porous sheet and a linear velocity of 46 m/h at a permeation pressure of 0.1 MPa at 298 K. The adsorption capacity of the DEA cartridge for FeCl₄⁻ as a model ion in equilibrium with 1 g-Fe(III)/L in 10 M HCl was 0.17 mmol-Fe(III)/DEA cartridge. No Pu leakage during the permeation of 5 mL of 10 M HCl-0.1 M HNO₃ containing Pu ionic species through the DEA cartridge was observed irrespective of the permeation rate ranging from 0.3 to 80 mL/min. A solution containing known amounts of ²³³U, ²⁴⁰Pu, and ²⁴¹Am in 10 M HCl-0.1 M HNO₃ was loaded onto the DEA cartridge. U and Pu were retained on the DEA cartridge, while Am was allowed to pass through the DEA cartridge. Subsequently, 7 M HNO₃ and 1 M HCl as eluents were permeated to elute U and Pu from the DEA cartridge, respectively. The decontamination factor of U in a Pu fraction, defined by dividing the activity of U in the feed solution by that of U in the Pu fraction, was 2.7 × 10⁵, which is desirable for the highly accurate ICP-MS determination of Pu for samples containing both U and Pu. The method using the DEA cartridge was validated by measuring isotopic compositions and quantities of U and Pu in a spent nuclear fuel sample by double-focusing magnetic sector ICP-MS.     

Preparation of an extractant-impregnated porous membrane for the high-speed separation of a metal ion

A novel impregnation method of extractants into a porous polymeric support is described. Bis(2-ethylhexyl)phosphate (HDEHP) was impregnated onto an n-octadecylamino group of the polymer chain grafted onto the pore surface of a porous hollow-fiber membrane. First, an epoxy-group-containing polymer chain was appended onto the porous membrane by radiation-induced graft polymerization of glycidyl methacrylate (GMA). Second, n-octadecylamine was added to the graft chain via an epoxy-ring opening reaction to yield a hydrophobic group density of 3.0 mmol/g of the GMA-grafted fiber. Finally, HDEHP was impregnated to the n-octadecylamino group. The amount of impregnated HDEHP of 2.1 mmol/g of the GMA-grafted fiber was attained while retaining the liquid permeability of the porous membrane. An yttrium solution was forced to permeate through the pores of the HDEHP-impregnated porous hollow-fiber membrane. The higher permeation rate of the yttrium solution led to the higher adsorption rate of yttrium because of a negligible diffusional mass-transfer resistance. In addition, a high stability of impregnated HDEHP was observed after the repeated use of adsorption with 50 mg-Y/L yttrium solution and elution with 7 M nitric acid.     

氮氧自由基配合物[Cu(NIT4Py)(IDA)]_n的合成与晶体结构(英文)

A novel one-dimensional (1D) Cu(Ⅱ) nitronyl nitroxide complex bridged by iminodiacetate dianion [Cu(NIT4Py)(IDA)]n,where NIT4Py=2-(4'-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and IDA= iminodiacetate dianion,was synthesized and structurally characterized by X-ray diffraction. It crystallizes in monoclinic,space group P21/c with a=0.921 09(10) nm,b=0.780 09(9) nm,c=2.486 3(3) nm,β=96.826(2)°. The Cu(Ⅱ) ion is five-coordinated with a distorted square-pyramidal geometry. Each iminodiacetate dianion bridges two Cu(Ⅱ) ions via a monodentate-tridentate mode into a 1D chain,and these 1D chains are further linked into a 2D network via hydrogen-bonding interactions.     

Macroreticular chelating ion-exchangers

Two macroreticular chelating ion-exchangers have been prepared and characterized. One contains the iminodiacetate group and the second contains the arsonate group as the ion-exchanging site. The macroreticular resins show selectivities among metal ions similar to those of the commercially available naicroreticular chelating resins. Chromatographie separations on the new resins are rapid and sharp.     

Chelating resins: Sorption characteristics in chloride media

The chelating resins Dowex A1 and its purified form, Chelex 100, contain the iminodiacetate functional group. The resins can exchange cations from solutions of high pH and anions from low pH solutions. Further, the iminodiacetate functional group provides chelating capability leading to special selectivity for multivalent ions such as Sb(V) and Hg(II). A systematic study of the sorption characteristics of Chelex 100 was initiated in our laboratory. Distribution coefficient values (K_d) were measured for Zn(II), Cd(II), Sn(IV), Sb(V) and Hg(II) as a function of HCl concentration and for Cu(II) and Pb(II) as a function of pH. The results obtained thus far indicate that Sb(V) and Hg(II) have high K_d values in acid chloride solutions. A radiochemical separation procedure was developed for the determination of Hg by neutron activation analysis using sorption onto Chelex 100.     

Multielement determination of trace metals in seawater by ICP-MS with aid of down-sized chelating resin-packed minicolumn for preconcentration

The multielement determination of trace metals in seawater was carried out by inductively coupled plasma mass spectrometry (ICP-MS) with aid of a down-sized chelating resin-packed minicolumn for preconcentration. The down-sized chelating resin-packed minicolumn was constructed with two syringe filters (DISMIC 13HP and Millex-LH) and an iminodiacetate chelating resin (Chelex 100, 200-400 mesh), with which trace metals in 50 mL of original seawater sample were concentrated into 0.50 mL of 2 M nitric acid, and then 100-fold preconcentration of trace metals was achieved. Then, 0.50 mL analysis solution was subjected to the multielement determination by ICP-MS equipped with a MicroMist nebulizer for micro-sampling introduction. The preconcentration and elution parameters such as the sample-loading flow rate, the amount of 1 M ammonium acetate for elimination of matrix elements, and the amount of 2 M nitric acid for eluting trace metals were optimized to obtain good recoveries and analytical detection limits for trace metals. The analytical results for V, Mn, Co, Ni, Cu, Zn, Mo, Cd, Pb, and U in three kinds of seawater certified reference materials (CRMs; CASS-3, NASS-4, and NASS-5) agreed well with their certified values. The observed values of rare earth elements (REEs) in the above seawater CRMs were also consistent with the reference values. Therefore, the compiled reference values for the concentrations of REEs in CASS-3, NASS-4, and NASS-5 were proposed based on the observed values and reference data for REEs in these CRMs.     

On-line preconcentration method for the determination of trace metals in water samples using a fully automated pretreatment system coupled with ICP-AES.

An automated on-line sample-preparation method using a computer-controlled pretreatment system (Auto-Pret AES system) coupled with ICP-AES was developed. In this work, an iminodiacetate chelating resin, packed in a mini-column and installed in the system was employed for the collection/concentration of 13 trace metals, including such toxic metals as Be, Cd, Cr, Cu and Pb. The limits of detection of the proposed method for trace metals were in the range of 0.001 (Be) -0.18 (Pb) ng mL-1. The enrichment factors for metal ions were about 19 times, when 5 mL of samples were used. The sample throughput was 11 h-1. The accuracy and the precision of the method were evaluated using river-water reference materials, SLRS-4 from NRCC, JSAC 0301-1 and JSAC 0302 from the Japan Society for Analytical Chemistry. The proposed method can be favorably applied to the collection/concentration of trace metals in natural water samples.     

Radiation-induced graft polymerization and sulfonation of glycidyl methacrylate on to porous hollow-fiber membranes with different pore sizes

An epoxy group containing monomer, glycidyl methacrylate, was grafted on to a porous hollow-fiber membrane, made of polyethylene, whose different pore sizes ranged from 0.2 to 0.5 μm. The resulting epoxy group was converted into a sulfonic acid group as a cation-exchange group to capture metal ions. The porous network was retained after grafting and subsequent sulfonation because the poly-GMA chains invaded the polymer matrix. An increase in the SO₃H group density of the graft chain decreased the permeability of pure water because the graft chains expanded toward the pore interior due to their mutual electrostatic repulsion. The ion-exchange adsorption of Pb ions during the permeation of a Pb(NO₃)₂ solution through the pores edged by the cation-exchange graft chains was observed with a negligible diffusional mass-transfer resistance.     

Arsenic speciation in water samples containing high levels of copper: removal of copper interference affecting arsine generation by continuous flow solid phase chelation

A simple continuous flow method is proposed to eliminate copper interference in arsenic speciation by hydride generation, based on the selective retention of this interfering ion in an iminodiacetate chelating resin previous to the hydride generation process. The arsines generated were cold trapped and measured by ICP/OES. The proposed method allows about 98% of the copper present in the samples to be removed. Minor co-retention of As(V) was observed as a result of electrostatic interaction between the arsenate anion and the nitrogen of the iminodiacetate group of the chelating resin Muromac A-1, the charge distribution of which is modified when copper is chelated. The species As(III), MMA and DMA were not retained in the microcolumn, probably because these species are mainly in the molecular form at the working pH value (4.5). In synthetic samples containing 50 g l^–1 of each arsenic species together with 100 mg l^–1 copper, the recoveries obtained were: As(V) 97.6%, As(III) 100%, MMA 99.8%, and DMA 99.9%. The method was applied to arsenic speciation in river water samples containing high levels of copper.     

IDA型Cu~(2 )-螯合亲和膜色谱法对牛肝过氧化氢酶纯化的研究(英文)

首次采用以改性纤维素为基质、亚氨二乙酸（ＩＤＡ）为取代配基的铜离子螯合膜色谱法对牛肝过氧化氢酶（ＢＬＣ）的分离纯化进行了研究。缓冲液的ｐＨ值对ＢＬＣ与螯合配基的结合影响显著。在选定的色谱条件下，ＢＬＣ粗酶液经ＩＤＡ型Ｃｕ２＋－螯合膜色谱柱一步纯化，比活性平均提高４．７倍，回收率为６７．７％。金属螯合膜色谱柱可用含０．２ｍｏｌ／Ｌ的咪唑或５０ｍｍｏｌ／ＬＥＤＴＡ－１ｍｏｌ／ＬＮａＣｌ的缓冲液再生，反复使用，后者比前者对柱子的再生效果更好。     

Separation of chitosan oligomers by immobilized metal affinity chromatography

A novel approach for chitosan oligosaccharide (COS) separation by immobilized metal affinity chromatography (IMAC) based on the differences in the interactions of chelated copper (II) ions with various COS (dimers, trimers, tetramers) is described. Polyhydroxylic chromatographic supports (agarose CL-6B and silica) were functionalized with various chelating functions such as iminodiacetate (IDA), carboxymethyl-aspartate (CM-Asp) and tris(carboxymethyl)ethylenediamine (TED). The COS retention capacities of the columns were between 2 and 6 mg/cm(3), depending on the chelating group. The COS were separated and/or enriched up to 95% for dimer and trimer and 90% for the tetramer, with yields of 60-95%.     

pH-induced reversible conformational and morphological regulation of polyleucine grafted polyallylamine assembly in solution

One of the essential parts in the molecular mechanism of biological properties is the structural changes of proteins induced by stimuli. An amphiphilic copolymer, poly(L-leucine) grafted polyallylamine as a simple model of proteins, has been prepared by NCA polymerization with free amino groups of polyallylamine as an initiator. Here, we report the pH-induced reversible conformational and morphological regulation of the amphiphilic copolymer, whose hydrophobic peptide graft chains have no pH-sensitive groups, in an aqueous solution containing 50 vol % trifluoroethanol. The conformation of the poly(L-leucine) graft chain was found to be strongly pH dependent. Under acidic conditions, where electrostatic repulsion existed between the neighboring protonated amine moieties of the polyallylamine main chain, the rapid aggregation of the poly(l-leucine) graft chains was disturbed, and the peptide graft chains formed a beta-sheet structure owing to the intramolecular hydrogen bonding among the graft chains. Under this condition, the amphiphilic polymer formed amyloid-like fibrils, and then the fibrils grew into a planer plate composed of staked beta-sheets. On the other hand, under basic conditions, the poly(L-leucine) graft chains showed conformational transitions from a beta-sheet structure to an alpha-helical conformation owing to a distortion of the regular arrangement of the peptide graft chains by the conformational change of the polyallylamine main chain, whose amino groups were deprotonated. The conformational transition resulted in a disturbance of the regular sheet assembly of the amphiphilic copolymer and induced morphological changes to the amorphous globular aggregates. The pH-induced conformational and morphological changes of the poly(L-leucine) graft polyallylamine were reversible and synchronized with the protonation of the polyallylamine main chain.     

Arsenic(V) Removal from Aqueous Solutions by Iron(III) Loaded Chelating Resin

A study of arsenic adsorption using iron(III) loaded chelating resin as adsorbent is presented. The experiments were carried out in batch mode by using aqueous solutions containing 1000 ppm As, and using an iron(III) loaded iminodiacetate resin (LEWATIT TP 207) with sorption capacity of 168 mg Fe/g resin. The equilibrium time for adsorption was found to be one hour under the experimental conditions used. The influence of pH was studied in the range of 0.8÷8.5. The highest arsenic adsorption was found at pH 1.7. Under these conditions the adsorption capacity for As was approximately 60 mg As/g resin.     

Rapid determination of chlorinated pesticides using CN-bonded cartridges followed by GC-ECD

Summary Gas chromatography of chlorinated pesticides in water is carried out after adsorption of a 50 mL sample using a cartridge containing 100 mg CN-bonded porous silica and extraction with 500 L pentane. The average recovery for eight organochloride pesticides at 1 ppb was >95%. The procedure described is simple, selective and reproducible.     

Removal of metallic impurities from mobile phases in reversed-phase high-performance liquid chromatography by the use of an in-line chelation column

An in-line stripper column packed with iminodiacetate chelation resin is placed between the pump and injection valve and shown to remove metallic impurities from an HPLC system. We used a test procedure based on assessing the relative peak asymmetries of 2,2'-bipyridyl, a chelating analyte and 4,4'-bipyridyl, a non-chelating analyte. Results from use of polyether ether ketone (PEEK) and stainless steel pumps are evaluated. Analytical columns with titanium/PEEK and stainless steel frits are used to assess the role of frits in metallic contamination. We demonstrated that although metal-free pumping systems contribute significantly lower metallic impurities than stainless steel systems, metal is nevertheless present in the mobile phase and the chelating stripper columns were found useful in protecting the analytical columns from contamination. The stainless steel frits were not found to be significant contributors to the contamination.     

Inductively coupled plasma mass spectrometric determination of heavy metals in sea-water samples after pre-treatment with a chelating resin disk by an on-line flow injection method

A new on-line flow injection (FI) pre-treatment system using a disk-type chelating resin (5 mm diameter, 0.5 mm thickness) was developed for the simultaneous multi-element determination of trace metals in sea-water samples by inductively coupled plasma mass spectrometry (ICP-MS). A chelating resin possessing an iminodiacetate (IDA) functional group was used for the collection of trace elements and the elimination of alkali and alkaline earth metals in highly concentrated salt solution. A 1 ml volume of a sea-water sample (pH 5.5) was applied to the chelating resin disk. Considering the removal efficiency for Ca, 50 mM ammonium acetate buffer solution (pH 5.5) was chosen as a sample carrier. The enriched trace metals were eluted with 0.1 M nitric acid and the eluate flowed into the ICP-MS system. The processing time for one sample was < 6 min (350 s). One of the important observations is the possibility of working with a low recovery, even lower than 50%. For example, several elements such as Mn, Cr, As, Mo, Ba and U, the recovery of which was < 50% in a batch-wise method, showed good linearity and reproducibility. The proposed method was evaluated by analyzing two kinds of sea-water certified reference materials, CASS-4 and NASS-5. Analytical data for eight heavy metals, V, Mn, Co, Ni, Cu, Mo, Cd and U, obtained from the present study agreed well with the certified values.     

Removal of Endotoxin from Human Serum Albumin Solutions by Hydrophobic and Cationic Charged Membrane

Removal of end6toxin from medicine injection is very important, becauseendotoxin withpotential biological activity causes pyrogenic and shock reactions in' mammals-'on...intravenous injection even as law as "an6gram amounts. Endotoxin, a constituent ofpotential contaminant of physiological fluids and aqueous solutions 'and very stable atextreme temperature and PH values. For removing endotoxin from solutions ofbiomolecules, such as HSA, adsorption techniques are usedl.' Many methods forendot…     

On-line preconcentration and determination of Au(III) in various environmental/industrial samples by flame atomic absorption spectrometry

A rapid and simple on-line method is described for the determination of Au(III) in various samples. The method is based on the sorption of gold(III) on Lewatit MonoPlus TP207 chelating resin including the iminodiacetate group, which is used as sorbent material and packed in a minicolumn. The chemical variables such as the pH of the sample solution, eluent type, interfering ions and concentrations of reagents, and instrumental variables such as sample loading volume, reagents flow rates, and tubing length, which affect the efficiency of the method were studied and optimised. Au(III) was sorbed on the chelating resin, from which it could be eluted with 3 mol L^?1 HCl, and then introduced directly to the nebuliser-burner system of FAAS. The limit of detection of the method was 0.2 µg L^?1 while the relative standard deviation was <4.0% for 20 µg L^?1 Au(III) concentration. The preconcentration factor was found to be 106 while the optimised sample volume was 15.3 mL. The accuracy of the method was verified by analysing the certified reference material. The developed method was applied successfully for the determination of gold in different samples with satisfactory results.     

Analysis of a basic drug by on-line solid-phase extraction liquid chromatography/tandem mass spectrometry using a mixed mode sorbent

Two on-line configurations using multiple 6- and 10-port valves were investigated for high-flow on-line extraction of a basic drug in rat plasma and human urine using a reversed-phase and a cation-exchange SPE sorbent. The first configuration studied was a single reversed-phase extraction cartridge (2.1 x 20 mm, 25 microm) using an optimized washing protocol. The results showed that up to 1.5 mL of sample (urine or plasma diluted 1:1) can be injected with limits of quantification (LOQs) as low as 100 pg/mL. The second configuration studied was the combination of a cation exchanger and a reversed-phase cartridge using at-column dilution. The results showed better LOQs than those obtained with the single cartridge at 10 pg/mL with the same injection volume. The mass spectrometer was operated in the multiple reaction monitoring (MRM) mode. All calibration curves gave an average of 5% relative standard deviation (RSD).