Extraction Chromatographic Resin Research Articles

Rapid sample digestion by fusion and chemical separation of Hf for isotopic analysis by MC-ICPMS

A new method for rapid sample digestion and efficient chemical separation of Hf and REE from rock samples for precise isotopic analysis is presented. Samples are digested by fusion in the presence of a lithium borate flux at 1100 °C and dissolved whilst molten in dilute nitric or hydrochloric acid. Prior to chemical separation using ion exchange techniques, Li and B from the flux material and Si from the sample are separated from the remaining major elements, REE and high field strength elements (HFSE) in the sample by Fe-hydroxide co-precipitation. The chemical separation of Hf is a two-stage procedure designed to first remove the remaining matrix elements (e.g. Fe, Ba) in the sample using standard cation exchange techniques, followed by separation of Hf from the REE and HFSE on TEVA extraction chromatographic resin. Hf yields are >90% and total procedural blanks are ca. 50 pg. Hf isotope ratios of a synthetic standard solution and replicate digestions of international rock standards BHVO-1 and BCR-1 measured on multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) reproduce similarly to ≤50 ppm (2 S.D.). The following elemental ratios are routinely obtained for elements, which interfere isobarically or may affect the ionisation and/or fractionation behaviour of Hf during analysis: 176Yb/ 176Hf<0.0001; 176Lu/ 176Hf<0.00001; Ti/Hf<0.05. This technique also provides a means of separating Nd from the REE fraction for isotopic analysis and, potentially, may be adapted for measurement of Lu/Hf ratios by isotope dilution techniques.

The development of flow injection technique for rapid uranium determination in urine samples

Today much attention has been paid to precise determination of actinide elements in various biological samples. The importance of actinide bioassay is caused by their radiological hazard due to the internal exposure. The present research is devoted to the development of a flow injection extraction chromatography (FI-EC) as an analytical procedure for rapid determination of uranium in urine by ICP-MS. The developed FI-EC-ICPMS system includes automated radiochemical separation based on the use of UTEVASpec extraction chromatography resin followed by immediate ICP-MS measurement. Microwave digestion is applied to decompose urine samples prior to the FI-EC-ICPMS measurement. The system automatically removes matrix substances, thus, overcomes problem of matrix effect during ICP-MS measurement. Only few cm3 of urine are required for a single uranium analysis because of a low detection limit of the ICP-MS method. The developed FI-EC-ICPMS system is fully automated and virtually does not require handwork. By the FI-EC-ICPMS method uranium determination could be performed within 8 min per urine sample.

The use of extraction chromatography resins to concentrate actinides and strontium from soil for radiochromatographic analyses

An analytical technique utilizing selective extractant resins to concentrate strontium and actinides from soil followed by separation with radiochromatography was evaluated. The technique was tested using uncontaminated soil samples spiked with a radionuclide tracer solution that were either microwave-aided acid digested or leached with a strong acid. Extraction of the strontium and actinides from the acidified solution was accomplished using a serial arrangement of Sr–Resin and TRU–Resin columns. The combined eluate solutions from the extraction resins were treated with HNO 3 and H 2O 2 to oxidize residual extractant and eluates prior to separation and analysis of the radionuclides by radiochromatography. Chromatograms obtained with larger soil mass loadings resulted in either incomplete peak resolution of the tracers or had highly variable peak elution times, indicative of an ionic interfering constituent(s). Better separations (e.g., chromatograms that resolved all radioactive constituents) were obtained when the sample mass loading was decreased, but with a concurrent decreased sensitivity for the radionuclides. Elemental analyses of the soil were conducted to provide data on the ionic constituents in unprocessed soil and post-processed soil samples. These results identified aluminum as an interfering contributor to the poor performance exhibited by the radiochromatographic separations.

Sequential analysis of Sr, Pu, Am and Cm: Low-level liquid radioactive effluents

A new sequential procedure for the analysis of Pu, Am, Cm and Sr in low-level liquid radioactive effluents is presented. The proposed method utilises an actinide specific extraction chromatographic resin (TRU- Resin) for the isolation and separation of the actinides. 90 Sr determination is accomplished via analysis of its progeny 'Y, which is purified with TBP extraction. The proposed method is simpler, faster and more robust than traditional ion exchange, extraction and precipitation methods used in routine analysis of actinides and 'Sr. The chemical yield of all analytes, when analysing 200 ml low-level effluent, is between 80-95%. 239 - 240 Pu is performed using standard separation procedures The low-level liquid waste at IFE originates from the operation of a small (thermal output 2 MW) research reactor and the production of radiopharmaceuticals. The waste from different locations at IFE is collected in large drums to allow the decay of the shortest living radionuclides before an evaluation on the discharge of the liquid is undertaken. Representative samples from the drums are then analysed for a-, P- and y-emirters. The composition of the liquid and the radionuclide content varies with the activities at the specific time. The general level of some radionuclides in the liquid is shown in Table 1. : Activities of some radionuclides in the low-level waste from IFE.

Development of rapid bioassay method for plutonium

For the internal dosimetry of plutonium, a urine bioassay method is very useful but requires several days to obtain the result of the analysis. To shorten the time required for the urine bioassay, a rapid method for plutonium analysis using the ICP-MS system was developed. In this chemical procedure, a microwave oven was applied for sample digestion, and an extraction chromatography resin was used for the separation of plutonium. The measurement time was extremely reduced by application of the ICP-MS as compared to alpha-spectrometry. The total analysis time was about 12 hours and the detection limit was 0.3 mBq/sample. The short analysis time and the low detection limit indicate that this method is useful not only for special monitoring but also for routine monitoring.

Development of novel composite sorbents for the removal of actinides from environmental and analytical solutions

A novel approach to preparing granular sorbents for the separation of actinides has been developed, where the extractant is directly immobilized in an inert matrix. This allows substantially higher extractant loadings in the sorbent than for conventional extraction chromatography resins. This approach utilizes polyacrylonitrile (PAN) as the inert matrix material. The well-known actinide extractant octyl (phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) has been loaded into sorbent granules at extractant loadings from 20 to 33 wt.% CMPO. The porosity of the PAN matrix allows the active material to have rapid and complete access to the solution containing the impurities, resulting in improved kinetics and higher sorption capacities. Sorbents containing CMPO were prepared using PAN as a binding matrix, and tested against commercially available actinide extraction chromatography resins. Direct comparative batch contact tests performed with TRU-ResinO and CMPO-PAN using an INEEL tank waste simulant, resulting in distribution coefficient (Kd) values for Am approximately 2-90 times higher for CMPO-PAN than for TRU-ResinŇ. Batch distribution coefficient (Kd) values for Pu were approximately 60-150 times higher for CMPO-PAN than for the TRU-ResinŇ. Acid dependency curves were generated for Am and Pu with CMPO-PAN over a concentration range of 1 mM to 5M HNO3.

223Ra for endoradiotherapeutic applications prepared from an immobilized227Ac/227Th source

A method is described for the production of223Ra (t1/2=11.4 d) in a quality useful for endoradiotherapeutic applications. The method is based on a long term operating generator with a source of227Ac (t1/2=21.7 years), from which223Ra is eluted. The227Ac was isolated from a231Pa source using the f-element selective extraction chromatographic material TRU-resin. The purified227Ac/227Th source was subsequently applied to another extraction chromatographic resin, containing the extractant P,P′-di(2-ethylhexyl)methanediphosphonic acid on silica (Dipex-2) and used as a generator for223Ra. From the generator column, the yield of223Ra was about 60 kBq per 100 kBq of227Ac with a highly effective separation of223Ra from the precursors. In production runs, the activity of227Ac was found to be 6×10-6relative to the eluted activity of223Ra. By using a second column of Dipex-2 for additional purification, the activity of Ac was reduced to below 7×10-8relative to223Ra with nearly quantitative recovery of223Ra. The described procedure resulted in a high purity223Ra preparation, potentially useful in,e.g., targeted radiotherapy of tumors.

An improved extraction chromatographic resin for the separation of uranium from acidic nitrate media

The preparation and characterization of a new extraction chromatographic resin exhibiting extraordinarily strong retention of hexavalent uranyl ion over a wide range of nitric acid concentrations and very high selectivity for U(VI) over Fe(III) and numerous other cations is described. This new material (designated U/TEVA-2) comprises a novel liquid stationary phase consisting of an equimolar mixture of diamyl amylphosphonate (DA[AP]) and Cyanex 923 ® (a commercially available trialkyl-phosphine oxide, TRPO) sorbed on silanized silica or Amberchrom CG-71. Cyanex 923 is shown to be preferable to a related TRPO, Cyanex 925 ®, due to its lower viscosity and higher selectivity for U(VI) over Fe(III). The retention of uranyl nitrate by the U/TEVA-2 resin, as measured by the k′ values (number of free column values to peak maximum) is >5000 from approximately 0.1 to 8 M HNO 3. The ability of the new resin to strongly and selectively retain U(VI) from such a wide range of acid concentrations, along with its favorable physical properties, make it a good candidate for application in the separation and preconcentration of U(VI) from complex environmental, biological, and nuclear waste samples for subsequent determination.

Simultaneous determination of Cd(II), Cu(II) and Pb(II) in surface waters by solid phase extraction and flow injection analysis with spectrophotometric detection.

A method for heavy metal monitoring using spectrophotometric detection is presented. Traces of Cu(II), Pb(II) and Cd(II) at the low microg l(-1) level can be determined simultaneously after both selective removal of metal interferences and preconcentration using 'extraction chromatographic resins'. Lewatit TP807'84, which contains di(2,4,4-trimethylpentyl)phosphinic acid as active component, was used as solid adsorbent. Two minicolumns containing this resin were used: one at pH 3.2 for the removal of interferences, such as Zn(II) and Fe(III), and the other at pH 5.5 for the selective preconcentration of the target analytes. Spectrophotometric determination used FIA methodology with sulfarsazene as chromogenic reagent and partial least-squares multivariate calibration. The method was successfully applied to the analysis of surface waters from the Llobregat river and ground water samples from wells in the Guadiamar basin. Accuracy, expressed in terms of recoveries, was in the range 80-120% and relative standard deviations were below 10%.

ICP-MS determination of Re at ultra trace levels in rock and soil samples

In order to prepare a sample for Re determination in rock and soil by inductively coupled plasma mass spectrometry (ICP-MS), an extraction chromatographic resin (TEVA resin, Eichrom Industry Inc.) was used. This resin extraction step satisfactorily separated Re from sample matrices and trace elements that cause isobaric interference during ICP-MS measurements. Total recoveries were compared using two other sets of samples to which elevated concentrations of Re spike of natural isotopic composition were added. The recoveries obtained for both sets of samples agreed very well with an average of 94 ± 3%. Total procedural blanks for Re in the course of this study ranged from 2.1–7.9 pg g−1. The method was applied to several standard rock samples and soil samples. For 0.5–1 g samples, the measured values ranged from 0.05 to 4.0 ng g−1.

Americium separations from nitric acid process effluent streams

Plutonium recovery operations offer several points at which americium removal may be attempted, and we are evaluating two classes of materials targeted at different steps in the process. Extraction chromatography resin materials loaded with three different alkylcarbamoyl phosphinates and phosphine oxides are assessed for Am removal efficiency and Am/Fe selectivity from 1–7M nitric acid solutions. Commercial and experimental anion exchange resins are evaluated for total alpha-activity removal from post-evaporator solutions whose composition, relative to the original nitric acid effluent, is reduced in acid and greatly increased in total salt content. With both classes of materials, americium and/or total-alpha reduction is sufficient to meet regulatory requirements even under sub-optimal conditions. Batch distribution coefficients and column performance data are presented.

Combined extraction chromatography and scintillation detection for off-line and on-line monitoring of strontium in aqueous solutions

This paper presents the application of a new sensor materials, whichcombine extraction chromatography and scintillation detection. The resultantsensor embodies the simultaneous dual functionality of selective extractionand radiation detection, which has been applied towards off-line and on-linemonitoring of radiostrontium in aqueous solutions. The sensor materials are(1) a mixture of commercially available Sr-selective extraction chromatographicresin and granular scintillator, (2) bis-4,4'(5')-tert-butylcyclohexano-18-crown-6(DtBuCH18C6) in 1-octanol coated on the surface of a scintillating glass and(3) inert chromatographic resin impregnated with the organic fluors, 2,5 diphenyloxazole,(PPO) and 1-4 bis(4- methyl-5-phenyloxazol-2-yl) benzene, (DM-POPOP) and eitherDtBuCH18C6 in 1-octanol or a proprietary extractant. For off-line measurements,the sensor materials are used in the same manner as the commercially availableextraction chromatographic resin, but rather than eluting the activity fromthe column, the scintillating extraction column is placed in a scintillationvial and counted without the introduction of liquid scintillation cocktail.For on-line measurements, the sensor materials are used in conjunction witha flow-cell scintillation detection system to assess the activity retainedby the extractant in real-time. Characterization of the detection efficiencyand regeneration capability of the extractive scintillator materials is evaluated.

Efficient preconcentration and separation of actinide elements from large soil and sediment samples

Large (approximately 10 g) soil and sediment samples are often required for analysis of low-level man-made actinides for monitoring environmental radioactivity. However, use of large environmental samples often results in significant chemical losses during chemical separations due to matrix interferences. We present a technique based on the ion-exchange resin Diphonix which selectively collects actinides and lanthanides into a common form, which then behaves uniformly and predictably during subsequent separation schemes. Diphonix is attractive for this purpose because it has an extremely high affinity for actinides and a low affinity for most common ions and is resistant to hydrofluoric acid. After being adsorbed onto Diphonix resin in a column mode at a pH approximately 1, actinides are completely eluted with 0.5 M 1-hydroxyethylidene-diphosphonic acid (HEDPA). After destruction of the HEDPA by ozonation or use of Fenton's reagent, Am, Pu, U, and Th are separated from each other and the remaining matrix by use of extraction chromatographic resins. We obtained high and consistent chemical recoveries (mean, 85%), as well as excellent chemical separations, for Am, Pu, U, and Th through the entire procedure for several 10-g soil and sediment samples.

Applications of Extraction Chromatography in the Development of Radionuclide Generator Systems for Nuclear Medicine

Numerous methods have been described for the separation and purification of radionuclides for application in diagnostic and therapeutic nuclear medicine, among them ion exchange, solvent extraction, and various forms of chromatography. Although extraction chromatography has previously been shown to provide a means of performing a number of separations of potential use in radionuclide generator systems, the application of the technique to generator development has thus far been limited. Recent work directed at improved methods for the determination of radionuclides in biological and environmental samples has led to the development of a series of novel extraction chromatographic resins exhibiting enhanced metal ion retention from strongly acidic media and excellent selectivity, among them materials suitable for the isolation of 212Bi, 90Y, and 213Bi. These resins, along with extraction chromatographic materials employing functionalized supports to improve their physical stability or metal ion retention prop...

Radiopharmaceutical and Hydrometallurgical Separations of Perrhenate Using Aqueous Biphasic Systems and the Analogous Aqueous Biphasic Extraction Chromatographic Resins

Poly(ethylene glycol) (PEG)-based aqueous biphasic systems (ABS) and the analogous aqueous biphasic extraction chromatographic (ABEC) resins have been investigated for the separation of perrhenate (ReO4-) from tungstate (WO42-) in alkaline tungstate media for radiopharmaceutical application and for the separation of perrhenate from molybdate (MoO42-) in hydrometallurgical application. Salts of the water-structuring anions OH-, WO42-, and MoO42- form ABS by salting-out PEG, while chaotropic anions such as ReO4- and the similar TcO4- quantitatively partition to the PEG-rich phase in such ABS. Perrhenate can thus be separated from solutions high in WO42- and OH- concentration, and the separation factors improve with an increase in the tungstate or hydroxide concentration. In addition, the ReO4- anion can be separated from load solutions high in MoO42- and SO42-. Perrhenate can also be separated under similar conditions using ABEC resins in both batch and chromatographic modes. The retained ReO4- can be eluted from the column with a simple water strip. The chromatographic separation of ReO4- from WO42- provided 97% of the loaded ReO4- in 20 mL. Unlike traditional technetium generators which are adversely affected by high parent ion concentrations, higher concentrations of the parent anion improve the retention of ReO4- onto ABEC resins. After exposure of the ABEC resins to radiation doses as high as 500 Mrad, an acceptable level of performance was maintained, although degradation of the resin (monitored using differential scanning calorimetry) was obvious.

Separation of Tc-99 in soil and plant samples collected around the Chernobyl reactor using a Tc-selective chromatographic resin and determination of the nuclide by ICP-MS

Technetium (Tc) is known to have high mobility in a soil–water system and also high bioavailability for plants, because the most stable form of Tc in natural surface environment is thought to be TcO−4 which is highly soluble. The chemical form of Tc, however, changes with environmental conditions. Thus, it is necessary, for realistic assessment, to obtain transfer parameters, such as transfer factors, under natural conditions. However, it is difficult to obtain these parameters using global fallout 99Tc in actual fields due to its low concentration. In this study, 99Tc concentrations in surface soil and plant leaf samples collected from forest sites within the 30-km zone around the Chernobyl reactor were measured for the first time. In the case of soil samples, a simple and rapid analytical method for determination of 99Tc is used which consists of volatilizing and trapping Tc in a combustion apparatus, purifying the Tc with an extraction chromatographic resin, and measuring it by inductively coupled plasma mass spectrometry (ICP-MS). For plant samples, a wet digestion method in combination with the resin is applied and the 99Tc is measured by ICP-MS. Concentrations of 99Tc in organic soil samples and leaves of strawberry (Fragaria vesca) range from 1.1–14.8 Bq kg−1 dry weight and 0.2–6.0 Bq kg−1 dry weight, respectively. Our results indicate that soil-to-plant transfer factors for Tc are similar to those for Cs.

Determination of 210Po in Reagent Samples by Alpha-Ray Spectrometry Using Extraction Chromatographic Resin

The determination of 210Po in phosphoric acid reagent by alpha-ray spectrometry using extraction chromatographic resin is presented. The decontamination factors of interference elements were measured. It was observed that HCl, HNO3, ascorbic acid, thioacetamide and Cu were free from 210Po but Pb contain small amounts of 210Po. 210Po in phosphoric acid samples was ranged from <8 to 2.4 Bq/l. The detection limit of 210Po in 50 ml of phosphoric acid is 8 mBq/l with a counting time of 1 day undercounting efficiency of 30%.

RADIOLYTIC STABILITY OF SOME RECENTLY DEVELOPED ION EXCHANGE AND EXTRACTION CHROMATOGRAPHIC RESINS CONTAINING DIPHOSPHONIC ACID GROUPS*

ABSTRACT The effect of 60Co irradiation on the Diphonix™, Diphosil and Diphonix-CS chelating ion exchange resins, and on two Dipex™ extraction chromatographic resins containing the P,P’-di(2-ethylhexyl) methanediphosphonic acid (H2DEH[MDP]) impregnated in the pores of a polymeric support (Dipex-1) and of silica (Dipex-2), respectively, has been investigated. The resins have been irradiated while in contact with HNO3 (Diphonix, Diphosil and Dipex resins) or NaOH (Diphonix-CS resin) up to an absorbed dose of about 200 Mrad. As a probe of the resin radiolytic degradation, metal uptake (both equilibrium and kinetics) and capacity measurements have been performed. Our results show that the Diphonix-CS resin properties are practically unaffected by irradiation under the experimental conditions used in this work. The Diphonix, Diphosil, and especially the Dipex resins suffer substantial capacity losses, but their affinity for actinide ions is not seriously compromised. On the other hand, the kinetics of metal uptake by the silica based Diphosil and Dipex-2 resins becomes substantially slower indicating that, from a radiolytic degradation standpoint, polymeric materials perform better than silica as supports for H2DEH[MDP] containing extraction chromatographic resins.

Determination of U isotopic ratios in environmental samples by ICP-MS

Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of trace elements in a variety of materials. For uranium, the concentration of 238U can be measured with a detection limit of less than 0.1 ppt in a few minutes. However, because of the extremely low 234U concentrations in environmental materials, it is necessary to separate U from the matrices and to remove interfering elements from the sample solution for measurement of the 238U/234U ratio by ICP-MS. In this study, a simple and rapid separation method for U with an extraction chromatographic resin (TEVA resin) was developed for ICP-MS and the U isotopic ratios in phosphogypsum samples, collected in Spain, were measured. The resin efficiently retained U in 6 M HCl medium and more than 98% of the U was easily eluted with the first 30 mL of 0.1 M HNO3. The separated solutions were free from most of the matrix elements and the concentrations of U in the solutions ranged from 35 to 70 ppb. The 238U/234U isotopic ratios in the solutions were measured by ICP-MS. Moreover, due to the presence of a higher number of 235U atoms in comparison with 234U, the 238U/235U isotopic ratios were also determined with high precision by ICP-MS. The results obtained agreed well with the ratios measured by alpha-spectrometry. The method for this determination is more rapid than alpha-spectrometry, and is considered to be more suitable for environmental monitoring.

Uptake of Metal Ions by Extraction Chromatography Using Dimethyl Dibutyl Tetradecyl-1,3-malonamide (DMDBTDMA) as the Stationary Phase

The uptake of several actinides and fission products such as U(VI), Pu(IV), Am(III), Eu(III), Cs(I), and Sr(II) from nitric acid solutions by a novel extraction chromatographic resin containing dimethyl dibutyl tetradecyl-1,3-malonamide (DMDBTDMA) has been investigated. The order of uptake follows the order Pu(IV) U(VI) Am(III) ∼ Eu(III) Sr(II) ∼ Cs(I). The possibility of this resin material sorbing trace concentrations of actinide ions from nitric acid solutions containing relatively larger amounts of Nd(III) and U(VI), as well as from simulated pressurized heavy water reactor (PHWR) waste solution, has been evaluated. The uptake of Am(III) in the presence of NaNO3, as well as in the presence of a macro concentration of Fe(III), has been investigated. The capacity of the resin for Am(III) and the elution behavior of the actinide ions from the resin were also studied.