Extraction Chromatographic Separation Research Articles

Development and optimization of high-performance extraction chromatography method for separation of rare earth elements

The effectiveness of commonly used extractants for chromatographic separation of rare earth elements (REEs) was compared. Columns loaded with similar molar concentrations of tributyl phosphate (TBP), di-(2-ethylhexyl) phosphoric acid (HDEHP), and N-Methyl-N, N, N-tri-octyl-ammonium chloride (Aliquat-336), with mineral acid as eluent were evaluated. Retention factors were determined, and separation efficiency was assessed based on the resolution data of the REEs acquired under the same elution conditions for each column. HDEHP demonstrated the best separation efficiency for the entire REE series (mean Rs = 2.76), followed by TBP (mean Rs = 1.52), while Aliquat-336 exhibited the lowest performance (mean Rs = 1.42). The HDEHP-coated column was then used to optimize the extraction chromatographic separation of the REEs. The primary challenge was to completely elute the heavy REEs (Tb – Lu) while maintaining adequate separation of the light REEs (La – Gd) within a reasonably short time. The stepwise gradient elution procedure improved the resolution between adjacent REEs, allowing the complete separation of the entire REE series within 25 minutes. Better separation efficiency for light REEs was achieved at higher column temperatures and a mobile phase flow rate of 1.5 mL/min in the tested domain of 20–60 °C, and 0.5–2.0 mL/min, respectively, resulting in plate heights (H) ranging from 0.011 to 0.027 mm.

Assessment of Radioecologically Relevant Radionuclides 14C, 99Tc, and 129I in Vitrified High-Level Nuclear Wastes from Spent Fuel Reprocessing

A method is proposed for quantifying the specific activities of radioecologically significant radionuclides, including 14C, 99Tc, and 129I, in vitrified high-level wastes. The conditions for the separation and purification of these radionuclides from potential interfering components are optimized and the yield coefficients and purification factors are determined. The quantification of 14C entails a three-fold distillation in CO2 followed by the measurement of the 14C counting rate in the purified solution by liquid scintillation spectrometry. 129I was determined by dissolving a sample in HNO3, five-fold extraction, and the subsequent measurement of the 129I counting rate in the purified solution using liquid scintillation spectrometry. The determination of 99Тс included dissolving a sample in the presence of ClO–, double extraction-chromatographic separation of 99Тс with an adsorbent impregnated with methyltrioctylammonium nitrate, followed by the determination of its activity by inductively coupled plasma–mass spectrometry. We have applied this approach to a simulator of vitrified high-level waste, labeled with radionuclides, and achieved satisfactory results. This approach will be instrumental in the analysis of the accumulated vitrified high-level wastes at the “Mayak” Production Association (Mayak PA). The results will be important for modeling the engineering safety barriers of a deep disposal site for radioactive wastes.

Stability of composite polymeric beads containing a calix[4]arene-mono-crown-6 ligand for radio-cesium separation

Bis-octyloxy-calix[4]arene-mono-crown-6 (BOCMC) is a selective ligand for Cs(I) cation, and has been used in solvent extraction method for its separation from acidic feed. Looking at the various advantages and ease of extraction chromatography separation method, an attempt was made to prepare stable composite beads containing BOCMC entrapped in a suitable polymeric matrix. Therefore, an attempt was made to prepare a series of composite polymeric beads containing BOCMC in polysulfone (PS), polyether sulfone (PES) and sodium alginate polymeric matrix. Preparations of the beads were attempted by dissolving the solid BOCMC in the polymer solution, and also by using the ligand solution in isodecanol/dodecane and ionic liquids and then mixing in the polymeric solution. Every attempt failed to get the desired quality of beads in PES and sodium alginate matrix. However, very good quality and stable beads were obtained when 25 mM ligand solution dissolved in C8mim.Tf2N ionic liquid was used in PS matrix. Detail study for the extraction chromatography separation of Cs(I) was studied with BOCMC/C8mim.Tf2N/PS composite beads. Detail investigations on the preparation, characterization, reusability and radiation stability of these beads have been studied and reported in details.

Application of Impregnated Resins for the Recovery of Actinides from Alpha Contaminated Solid Waste

AbstractAn extraction chromatographic separation scheme has been developed using impregnated resin for the processing of actual plutonium contaminated solid analytical assorted waste. The effluent obtained on anion exchange chromatography during plutonium purification step was processed by tri‐n‐butyl phosphate (TBP) and tetra 2‐ethylhexyl diglycolamide (T2EHDGA) augmented XAD‐4 resin to remove uranium and americium, respectively, while Ag ion was electrochemically separated further. The augmentation of TBP and T2EHDGA functionalities on XAD‐4 have been evidenced by FTIR spectroscopy, TG and DSC analysis. The modification in surface morphology on augmentation has been investigated by SEM, while elemental mapping and EDS heteroatom analysis indicated the successful functionalization/impregnation of the resin. In case of U removal by TBP augmented XAD‐4 resin, starting from 3 gL−1 feed in 7.2 M HNO3, a maximum of 93 % U was found to be loaded on the column, which can quantitatively be back extracted by 0.01 M HNO3. Despite ∼10 % reduction in loading capacity during the 3rd consecutive cycle, the efficacy of this column chromatographic separation of U has been demonstrated successfully. The raffinate of this step was used as feed for Am3+ separation using T2EHDGA‐XAD‐4. A maximum of 98 % loading and almost quantitative elution have been observed during this step and the performance recyclability has been checked for three consecutive cycles. The loading of U and Eu (Am analogue) has been evidenced by elemental mapping and energy‐dispersive X‐ray spectroscopy (EDS)analyses of loaded resin.

Secondary Metabolites with Anti-Inflammatory from the Roots of Cimicifuga taiwanensis.

The genus Cimicifuga is one of the smallest genera in the family Ranunculaceae. Cimicifugae Rhizoma originated from rhizomes of Cimicifuga simplex, and C. dahurica, C. racemosa, C. foetida, and C. heracleifolia have been used as anti-inflammatory, analgesic and antipyretic remedies in Chinese traditional medicine. Inflammation is related to many diseases. Cimicifuga taiwanensis was often used in folk therapy in Taiwan for inflammation. Phytochemical investigation and chromatographic separation of extracts from the roots of Cimicifuga taiwanensis has led to the isolation of six new compounds: cimicitaiwanins A–F (1–6, respectively). The structures of the new compounds were unambiguously elucidated on the basis of extensive spectroscopic data analysis (1D- and 2D-NMR, MS, and UV) and comparison with the literature data. The effect of some isolates on the inhibition of NO production in lipopolysaccharide-activated RAW 264.7 murine macrophages was evaluated. Of the isolates, 3–6 exhibited potent anti-NO production activity, with IC50 values ranging from 6.54 to 24.58 μM, respectively, compared with that of quercetin, an iNOS inhibitor with an IC50 value of 34.58 μM. This is the first report on metabolite from the endemic Taiwanese plant-C. taiwanensis.

Secondary Metabolites with Anti-Inflammatory Activities from One Actinobacteria Amycolatopsis taiwanensis.

Phytochemical investigation and chromatographic separation of extracts from one new actinobacteria strain Amycolatopsis taiwanensis that was isolated from soil of Yilan township, in the north of Taiwan, led to the isolation of nine new compounds, amycolataiwanensins A–I (1–9, resp.), and one new natural product, namely amycolataiwanensin J (10). The structures of the new compounds were unambiguously elucidated on the basis of extensive spectroscopic-data analysis (1D- and 2D-NMR, MS, and UV) and comparison with literature data. The effect of some isolates on the inhibition of NO production in lipopolysaccharide-activated RAW 264.7 murine macrophages was evaluated. Of the isolates, 3, 5, 7 and 8 exhibited potent anti-NO production activity, with IC50 values of 17.52, 12.31, 17.81 and 13.32 μM, respectively, compared to that of quercetin, an iNOS inhibitor with an IC50 value of 35.94 μM. This is the first report on indole metabolite from the genus Amycolatopsis.

Analysis of the Processes of Extraction–Chromatographic Separation in a Cascade of Mixing–Settling Extractors

Analysis of the Processes of Extraction–Chromatographic Separation in a Cascade of Mixing–Settling Extractors

Saccharpiscinols A-C: Flavans with Potential Anti-Inflammatory Activities from One Actinobacteria Saccharomonospora piscinae.

Phytochemical investigation and chromatographic separation of extracts from the actinobacteria strain Saccharomonospora piscinae that was isolated from dried fishpond sediment of Kouhu township, in the south of Taiwan, led to the isolation of three new compounds, saccharpiscinols A–C (1–3, respectively), and three new natural products, namely (2S)-5,7,3′,4′-tetrahydroxy-6,8-dimethylflavanone (4), methyl-4-hydroxy-2-methoxy-6-methylbenzoate (5), and (±)-7-acetyl-4,8-dihydroxy-6-methyl-1-tetralone (6). Compounds 4–6 were reported before as synthesized products, herein, they are reported from nature for the first time. The structures of the new compounds were unambiguously elucidated on the basis of extensive spectroscopic data analysis (1D- and 2D-NMR, MS, and UV) and comparison with literature data. The effect of some isolates on the inhibition of NO production in lipopolysaccharide-activated RAW 264.7 murine macrophages was evaluated. Saccharpiscinol A showed inhibitory activities against LPS-induced NO production.

Theoretical Analysis of Periodic Processes of Extraction-Chromatographic Separation in a Closed Cascade of Apparatuses

Theoretical Analysis of Periodic Processes of Extraction-Chromatographic Separation in a Closed Cascade of Apparatuses

Extraction chromatographic separation of thorium by silica gel impregnated with cyanex 923

Solvent impregnated silica gel material was prepared for thorium recovery from its aqueous nitrate solutions using the neutral phosphine oxide extractant, cyanex-923 in toluene. This was achieved by adsorption of the extractant onto the solid phase in three steps. The obtained adsorbent was characterized by means of Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The relevant factors of extraction such as influence of acid concentration, flow rate and impregnated cyanex 923 amount were optimized by equilibrium column experiments. The results revealed that thorium loaded on 0.5 g cyanex-silica achieved with about 99.6% efficiency. Selective elution of the loaded thorium was carried out in two steps using both sulfuric and hydrochloric acids after volume optimization. Based on the obtained optimum factors, validation of the studied impregnated solid phase occurred on three certified granite samples where the practical applicability was then examined upon two geological samples bearing Th(IV) collected from Abu Zeneima mineralization, South-Western Sinai.

Rapid method for sequential determination of Pu and Am in soil and sediment samples by sector-field inductively coupled plasma mass spectrometry

New method was developed to analyze Pu and Am sequentially for soil and sediment by inductively coupled plasma mass spectrometry (ICPMS). The developed method uses conc. HNO3 to leach Pu and Am, Fe(OH)3 coprecipitation to remove alkali and alkaline metals, extraction chromatographic separation using UTEVA, DGA and TEVA resins to remove interfering elements (IEs) and separate Pu and Am from each other, and sector field-ICPMS to measure Pu and Am. The analysis of four standard reference materials showed that both Pu isotopes and 241Am were accurately determined by this method, as a result of its excellent decontamination ability of IEs. Especially the high decontamination factor of Pu [DF(Pu), 4.2 × 102] in Am fraction and high DF(Am) (7.0 × 103) in Pu fraction sufficiently eliminated the cross interference between 241Pu and 241Am in ICPMS measurement. In addition, stable and high chemical recoveries were achieved for Pu (71–91%) and Am (70–88%). The low LODs of Pu isotopes, short analytical time (14 h) and high DFs of IEs allows this method to sequentially analyze Pu and Am, for both global fallout and nuclear accident sourced samples.

New C,O-Glycosylflavones from the Genus Silene

Chromatographic separation of extracts from the aerial parts of three Silene species (Caryophyllaceae) isolated 26 flavonoids including the four new C,O-glycosylflavones acacetin-6-C-(2″-O-β-D-glucopyranosyl)-β-D-glucopyranoside-7-O-β-D-glucopyranoside (sileneside D, 1) from S. jeniseensis Willd., apigenin-6-C-(2″-O-β-D-glucopyranosyl)-β-D-glucopyranoside-8-C-α-L-arabinopyranoside (sileneside E, 2) and genkwanin-6-C-(2″-O-β-D-glucopyranosyl)-β-D-glucopyranoside-8-C-α-L-arabinopyranoside (sileneside F, 3) from S. italica (L.) Pers., and apigenin-6-C-(2″-O-β-D-xylopyranosyl)-β-D-glucopyranoside-7-O-(6″″-O-feruloyl)-β-D-glucopyranoside (sileneside G, 4) from S. dioica (L.) Clairv. The structures of 1–4 were studied using UV, IR, and NMR spectroscopy and mass spectrometry.

Development of a radiochemical method for extraction chromatographic separation of Pb and Bi radioisotopes of forensic and environmental interest

Abstract This work describes the purification and separation of some radionuclides of 210Pb and/or 210Bi that might be used in calibration of nuclear spectroscopic instruments for forensic purposes and environmental studies. The retention and desorption investigations have been done by Dowex HCR-S/S resin as the cationic exchanger by batch mode. Full retention of metal ions was achieved in 0.1 M HNO3 solution after an equilibration period of 2 h at room temperature. The uptake of Pb and Bi is reached to more than 95 and 85%, respectively. Desorption studies by several reagents indicated that 1 M citric acid and ammonium acetate are efficient to elute and separate Bi and Pb. Taking into consideration all the above obtained results, column applications packed by the Dowex HCR-S/S resin were carried out to separate 214,210Pb and 214Bi radionuclides either in TENORM-concentrate or old certified reference of 226Ra solution. The column application results revealed that the recovery of Pb and Bi radionuclides was ∼93%. In the radiochemical part, the eluted Bi was impure due to presence of 23% Pb. In contrast, 70% of pure Pb was obtained. Thus, the radionuclides 210Pb can be recovered from several waste resources by this method. It can be concluded that the Dowex HCR resin can be an alternative economic material that could be used to produce 210Pb from the TENORM wastes generated from some strategic industries.

Automated extraction chromatographic radionuclide separation system for analysis of 90Sr in seawater

After the Fukushima Dai-ichi nuclear power plant disaster, the demand for a rapid method for the detection of environmental radioactivity increased drastically. Since the development of extraction chromatography using resins, analytical methods have advanced significantly in terms of simplicity and required labor. Herein, a home-made automated separation system that is applicable radio-extraction chromatographic separation techniques is reported. A simple, rapid, and high-throughput method was developed using this home-made automated separation system to analyze radiostrontium in seawater in emergency and routine situations. For emergency situations, radiostrontium in seawater is pre-concentrated on a cation exchange resin and consecutively purified using the Sr-resin. Fifty minutes are required for the purification of 90Sr in four samples (100 ml). The minimum detectable activity (MDA) for 90Sr is 0.2 Bq kg−1 at 100 min counting, with a recovery of 70% and counting efficiency of 95% in the scintillation mode. For routine monitoring, 90Y that is in equilibrium with 90Sr is first separated from the sample matrix using DGA. Treatment of 30 L of each seawater sample requires ~2 h. The MDA for this method is 0.3 mBq kg−1 at 400 min counting with a recovery of 70% and counting efficiency of 67% in the Cerenkov mode. By employing the developed method, the measured 90Sr in seawater collected from the coastal area of Korea is 0.92 ± 0.18 mBq kg−1, which is comparable to that reported previously. The measurements were obtained using a liquid scintillation counter, and the entire separation process was performed by employing the home-made separation system.

A Survey of Extraction Chromatographic f-Element Separations Developed by E. P. Horwitz

ABSTRACTAn extensive suite of f-element extraction chromatographic (EXC) resins was developed by E. Philip Horwitz and his groups at Argonne National Laboratory, PG Research Foundation, and Eichrom Technologies, Inc. The separation character of the specific resins is largely determined by the extractant physisorbed on the solid support. Modelled after solvent extraction systems employing the same extractants, TEVA, UTEVA, TRU, DGA, Actinide, and the LN family of resins have become benchmarks for research comparisons and are available for commercial applications. The f-elements separations community has applied these resins in a multitude of analytical fields from nuclear medicine isotope production to environmental analysis. As the field of extraction chromatography begins to explore innovative solid supports and ingenuity in the applicability of the EXC resins themselves, the tremendous contributions of Horwitz must be considered. This review examines the EXC materials developed by Horwitz, specifically for f-elements, and discusses separation schemes and process development.

New phenolics from Dianella ensifolia

Phytochemical investigation and chromatographic separation of extracts from the aerial parts of Dianella ensifolia (L.) DC. (synonym Dianella nemorosa Lam. Ex. Schiler f.) led to the isolation of 10 compounds, the structures of which were determined by HR-ESI-MS and 1 D- and 2 D-NMR spectroscopies, and by comparisons with published studies. Among the isolated compounds were three flavans, a biflavan, a biflavone, a tetralone, a naphthalen glycoside, an aromatic compound, and two steroids. Six of these were known chemicals, while three were identified as new compounds: 7-acetyl-4R,8-dihydroxy-6-methyl-1-tetralone, 2(S),2′,4′-dihydroxy-7-methoxyflavan, and diaensi-biflavan. 2(S),7,4’-dimethoxy flavan was obtained for the first time as a natural product.

Analysis of Extraction Chromatographic Separation of a Binary Mixture in a Series of Multistage Columns

Two processes of multistage extraction chromatographic separation of components (with and without recycling) are theoretically studied under various conditions of loading of a mixture to be separated to the apparatus. A mathematical description of the separation processes is presented. It is shown that the separation of components in the process with recycling requires an order of magnitude fewer equilibrium stages than separation in the process without recycling. Moreover, the productivity of the process with recycling, which is determined by the duration of loading to the apparatus, is an order of magnitude higher.

Investigation into the Extraction–Chromatographic Separation of a Binary Mixture in a Series of Multistage Columns

The semibatch multistage extraction chromatographic separation of a binary system of components has been experimentally studied under various conditions of loading of the mixture to the apparatus. An acceptable fit of the previously developed mathematical model of the process to the experimental results is determined.

Adaptation of an Analytical Procedure for Concurrent Determination of Np and Pu in clay samples

AbstractNp and Pu are two important actinides of concern for the safe long-term disposal of nuclear waste. Both actinides are, in addition, constituents of global nuclear fallout. Investigation of their environmental behavior requires ultra-sensitive analytical methods, but current methods for a concurrent determination in clay minerals are lacking. In the present study, a Pu isotope was investigated for use as a non-isotopic yield tracer for Np in extraction, purification, and mass spectrometric determination of Np and Pu isotopes in clay materials. Inductively coupled plasma mass spectrometry was used in this developmental study, but the method is intended for future ultra-trace analysis of global-fallout Np and Pu in clay-rich soil materials by the more sensitive accelerator mass spectrometry. Another field of application may be the investigation of diffusion patterns of actinides in compacted clay liners and potential host rocks for radioactive waste disposal. The analytical procedure includes the following steps: (1) extraction of Np and Pu from clay samples; (2) adjustment of Np and Pu to Np(IV) and Pu(III); (3) pre-concentration of Np and Pu by co-precipitation with iron hydroxide; (4) adjustment of Pu to Pu(IV); (5) extraction chromatographic separation of Pu and Np from iron and matrix elements; and (6) determination of Np and Pu by mass spectrometry. The analytical procedure was applied successfully to spiked montmorillonite and illite test portions of up to 1 g. High chemical yields near 90% were obtained for both Np and Pu. The suitability of Pu as a non-isotopic tracer for Np was indicated by Np/Pu chemical yield ratios close to unity. Accurate pH adjustment during the reductive co-precipitation and short processing times are vital to obtain high chemical yields and Np/Pu yield ratios close to unity.

Separation of f-elements by resins impregnated with amides of pyridine-2,6-dicarboxylic acid

Chemistries of trivalent lanthanides and actinides under aqueous processing conditions are so similar that their satisfying separation is extremely challenging. Preparation of a functionalized solid material by impregnation of a support resin with an organic extraction phase is one of possible routes for novel materials development. The ortho- and para-dialkyl-diaryl-pyridine-2,6-dicarboxyamides were impregnated into two macroporous matrices (PS-DVB and PMA). Influence of the diamide structure, matrix type and conditions for effective extraction chromatography separation of Am(III) from Eu(III) was studied in dynamic conditions. The prepared sorbents exhibited more strong adsorptions of Am(III) to compare with Eu(III). Maximal separation factor (~ 90) was achieved with use of citrate ion as complexing eluent.