High Concentrations Of Polyethylene Glycol Research Articles

The efficiency and competitiveness of three Mesorhizobium sp. strains nodulating Acacia senegal (L.) Willd. under water deficiency conditions in the greenhouse

The combined effects of drought and salinity were investigated on the growth, efficiency and competitiveness of three Mesorhizobium sp. strains (ORS 3416, ORS 3428 and ORS 3437) isolated from Acacia senegal (L.) Willd. Sixteen combinations of polyethylene glycol (PEG) 6000 (0, 6, 12, 20%, w/v) and NaCl (0.005, 0.5, 1, 1.5%, w/v) were used to study rhizobial strains growth in screw-capped tubes containing yeast extract mannitol liquid medium. Whatever the combination, the strains grew. However, high concentrations of PEG 6000 and NaCl were depressed on rhizobial growth but strain ORS 3428 was the most tolerant. The effect of rhizobial inoculation on growth of A. senegal plants was also examined under non-limited (100% of water holding capacity, WHC) and water-limited conditions (50% WHC) in the greenhouse for 4 months on non-sterile sandy soil. A significant decrease in the nodulation rate, nodule dry weight, plant height and shoot dry weight was observed under water-limited conditions. Nevertheless, inoculation with the three selected Mesorhizobium strains significantly improved nodulation and A. senegal plant growth under water-limited conditions. Whatever the irrigation condition, strains ORS 3428 and ORS 3437 were more competitive than ORS 3416. These rhizobial strains may prove valuable for inoculation of Acacia senegal plants grown for transplantation to dry saline habitats.

Perturbation of solute transport at a liquid–liquid interface by polyethylene glycol (PEG): implications for PEG-induced biomembrane fusion

The effect of polyethylene glycol 400 (PEG) dissolved at various concentrations (0-40% v/v) in water, on the interfacial transport of methyl nicotinate across an aqueous-isopropyl myristate interface was investigated with a rotating diffusion cell. At four temperatures studied (20-37 °C), the presence of PEG decreased the rate of solute transfer both into and out of the organic phase in a concentration-dependent fashion. The bulk partition coefficient of the solute (organic/aqueous) increased with increasing PEG in the aqueous phase. Analysis of the temperature dependence of the interfacial transfer kinetics allowed thermodynamic activation energy parameters for the phase transport process to be determined. Although the free energy of activation (ΔG(≠)) for transfer was not affected by PEG, the relative enthalpic and entropic contributions were dramatically altered. At PEG concentrations of 10-40% v/v the enthalpic portion of ΔG(≠) was decreased by about a factor of two, while the entropic contribution (which is large and positively favorable in the absence of PEG) was reduced considerable such that it was totally eliminated at higher PEG levels. These observations suggest novel and direct experimental evidence for the concept that high PEG concentrations substantially alter water structure at an aqueous solution-organic liquid biomembrane model interface. The results support the hypothesis that the critically important function of PEG in inducing cell-cell and liposome-liposome fusion is to remove the hydration layer that impedes the close apposition of converging phospholipid bilayers.

Effects of Seed Priming on Germination and Seedling Growth Under Water Stress in Rice

For disclosing the effects of seed priming with water and polyethylene glycol (PEG) on physiological characteristics in rice ( Oryza sativa L.), the seeds of 4 rice cultivars were treated with H 2O and different concentrations of PEG before germination. Primed or nonprimed (control) seeds were then germinated under drought stress conditions simulated with PEG in a serious of concentrations. The contents of proline, soluble protein (SP), total soluble sugar (SS), malonicdialdehyde (MDA), and the activities of phenylalanine ammonia lyase (PAL), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in the seeds or seedlings after 10-day stress were tested, and the indices for seed germination and seedling characteristics were determined. In seeds with priming treatments, the contents of proline and SP were significantly higher than those in the corresponding controls, and the contents of SS and MDA were significantly lower than those in the controls. Seed priming accelerated the process of glucose metabolism, enhanced the activities of PAL, SOD, CAT, and POD in the stressed seeds of all cultivars. Compared to hydro-priming, priming with PEG in a proper concentration had a better effect on seed germination and seedling growth under drought stress, and the optimal priming concentrations of PEG were 20% for Gangyou 527 ( indica hybrid rice) and 10%–15% for Nongken 57 (conventional japonica rice). Even higher concentrations of PEG had negative effects on seed germination. Moderate priming intensity improved metabolism of rice seed, germination indices, seedling quality, and drought tolerance of seedlings under drought stress for all cultivars. However, such effects had limited capability, and severe drought stress inhibited germination and caused damages of rice seedlings. Rice cultivars had significant impact on priming effect, and indica rice showed better performance than japonica rice.

Investigation of PEG Crystallization in Frozen PEG–Sucrose–Water Solutions: II. Characterization of the Equilibrium Behavior During Freeze-Thawing

Our objective was to characterize, by DSC and XRD, the equilibrium thermal behavior of frozen aqueous solutions containing polyethylene glycol (PEG) and sucrose. Aqueous solutions of (i) PEG (2.5-50% w/w), (ii) sucrose (10% w/v) with different concentrations of PEG (1-20% w/v), and (iii) PEG (2% or 10% w/v) with different concentrations of sucrose (2-20% w/v), were cooled to -70 ° C at 5 ° C/min and heated to 25 ° C at 2 ° C/min in a DSC. Annealing was performed for 2 or 6 h at temperatures, ranging from -50 to -20 ° C. Experiments under similar conditions, on select compositions, were also performed in a powder X-ray diffractometer. Two endotherms, observed during heating of a frozen PEG solution (10% w/v), were attributed to PEG-ice eutectic melting and ice melting, and were confirmed by XRD. At higher PEG concentrations (≥ 37.5% w/w), only the endotherm attributed to the PEG-ice eutectic melting was observed. Inclusion of sucrose decreased both PEG-ice melting and ice melting temperatures. In unannealed systems with a fixed sucrose concentration (10% w/v), the PEG-ice melting event was not observed at PEG concentration ≤ 5% w/v. Annealing for 2-6 h facilitated PEG crystallization. In unannealed systems with a fixed PEG concentration (10% w/v), an increase in the sucrose concentration increased the devitrification but decreased the PEG-ice melting temperature. The PEG-ice melting temperatures obtained by DSC and XRD were in good agreement. In ternary systems at a fixed PEG to sucrose ratio, the T' g as well as the PEG-ice melting temperature were unaffected by the total solute concentration. XRD confirmed the absence of a PEG-sucrose-ice ternary eutectic. When the PEG to sucrose ratio was systematically varied, the PEG-ice and ice melting temperatures decreased with an increase in the sucrose concentration. However, at a fixed PEG to sucrose ratio, the PEG-ice melting temperature, was unaffected by the total solute concentration.

Crystallization and preliminary diffraction analysis of an engineered cephalosporin acylase.

Crystallization conditions are reported for an engineered cephalosporin acylase based on the sequence of glutaryl-7-aminocephalosporanic acid acylase from Pseudomonas strain N176. Initial crystals were grown using polyethylene glycol as a crystallizing agent; however, these crystals diffracted poorly and exhibited high mosaicity. A dehydration procedure in which crystals were transferred to a solution containing a higher concentration of polyethylene glycol as well as glycerol improved the diffraction quality such that a 1.57 A diffraction data set could be obtained.

Insights of the effects of polyethylene glycol 400 on mammalian and avian nerve terminals

Polyethylene glycol (PEG) has been widely used as a solvent among other applications. An ideal solvent is one that does not interfere with an in vitro biological system, unless it is a bioactive agent. Herein, a facilitatory neurotransmission effect was exhibited by PEG (20 microM) in mammalian (67 +/- 12.5%, n = 4) and avian (74 +/- 6.8%, n = 6) neuromuscular preparations. In curarized preparations, PEG did not reverse the neurotransmission blockade induced by D-tubocurarine (D-Tc, 5.8 microM, n = 6) as promoted by neostigmine (12 microM, n = 4). A possible presynaptic action of PEG was ruled out, because quantal acetylcholine (ACh) content was similar to the control Tyrode-incubated mammalian preparation. PEG showed improved sarcolemmal sensitivity, both under direct (sarcolemma) and indirect stimulation (motor axon), because it was able to release calcium from the sarcoplasmic reticulum, even when 30 microM dantrolene (n = 5) was previously applied. Neurotransmission decreased at a higher PEG concentration (100 microM, n = -6) in the depolarized membrane, but it did not alter normal muscle fiber morphology. In addition, it partially recovered twitch tension amplitude (55 +/- 5.7%) after washing the preparations. More than a simple solvent, we suggest that PEG 400 is able to act on the sarcolemmal membrane, probably at the triad level, which is in line with its well-known ability as drug carrier.

Accelerated Fibrillation of α-Synuclein Induced by the Combined Action of Macromolecular Crowding and Factors Inducing Partial Folding

To better model the characteristics of crowded intracellular environments, we examined the effect of several factors known to induce partial folding and accelerated fibrillation of alpha-synuclein in dilute solutions, on the fibrillation of this protein in a crowded milieu. We found that low pH, certain metals and pesticides, polyanions, polycations and low concentrations of organic solvents cause a significant acceleration of alpha-synuclein fibrillation in the presence of high concentrations of polyethylene glycol. This suggests that the fibril-promoting effects of factors inducing partial folding of alpha-synuclein and the fibril-stimulating effects of macromolecular crowding are relatively independent and thus might act additively or even synergistically.

Prevalence of increased serum creatine kinase activity due to macro-creatine kinase and experience of screening programmes in district general hospitals

Macro creatine kinase type 1 (MCK1) may be the cause of elevated total serum CK activity, which can lead to diagnostic confusion. There is evidence that this problem is poorly recognized perhaps due to a lack of information on its prevalence. Precipitation with polyethylene glycol (PEG) has been described for the detection of MCK1 but has not been fully evaluated. We introduced a screening programme to detect elevated serum total CK due to MCK1 and determine the prevalence of this problem using PEG precipitation with confirmation by gel filtration chromatography (GFC). The results were compared with those from a laboratory which selected samples for further investigation during the clinical validation process. We also studied characteristics of the PEG precipitation test including sensitivity and specificity when compared with GFC. Over 2 years we screened 368 patients. In 17 cases the proportion of CK activity precipitated by PEG was relatively high and the presence of MCK1 was confirmed in seven by GFC. In a second laboratory, over a period of 5 years, 11 samples were selected during the clinical validation process for further study and MCK1 was the cause of the elevated CK activity in six cases. PEG precipitates a proportion of normal, uncomplexed CK and this is increased by increasing serum globulin concentration and by higher concentrations of PEG. The prevalence of elevated serum CK activity due to MCK1 was approximately 2%. Laboratories should consider introducing a systematic screening programme based on PEG precipitation.

Optimisation of aqueous two-phase extraction of human antibodies

The purification of human antibodies in an aqueous two-phase system (ATPS) composed of polyethylene glycol (PEG) 6000 and phosphate was optimised by surface response methodology. A central composite design was used to evaluate the influence of phosphate, PEG and NaCl concentration and of the pH on the purity and extraction yield of IgG from a simulated serum medium. The conditions that maximise the partition of IgG into the upper phase were determined to be high concentrations of NaCl and PEG, low concentrations of phosphate and low pH values. An ATPS composed of 12% PEG, 10% phosphate, 15% NaCl at pH 6 was further used to purify human monoclonal antibodies from a Chinese Hamster Ovary (CHO) concentrated cell culture supernatant with a recovery yield of 88% in the upper PEG-rich phase and a purification factor of 4.3. This ATPS was also successfully used to purify antibodies from a hybridoma cell culture supernatant with a recovery yield of 90% and a purification factor of 4.1.

Technical improvement in the purification of enzymes from red algae using an aqueous two-phase partitioning system

SUMMARY The effective elimination of phycobiliproteins from crude enzyme preparation of the red alga Caloglossa continua (Okamura) King et Puttock (Ceramiales, Florideophyceae) was investigated in an aqueous two-phase partitioning system (ATPS) by changing the concentrations of polyethylene glycol (PEG) and ammonium sulfate (AS). The phycobiliproteins shifted from the AS-rich lower phase to the PEG-rich upper phase in high PEG and AS concentrations. The best ATPS condition for the elimination of phycobiliproteins from the lower phase was obtained by the combination of 20% (weight/volume; w/v) PEG and 16% (w/v) AS. However, the recovery of aldolase and mannitol-1-phos-phatase activities was significantly reduced. For purification of the enzymes, a combination of 15% (w/v) PEG and 16% (w/v) AS was the best ATPS condition, because a high specific activity and recovery of the enzymes were obtained. Under these conditions, 98% of the phycobiliproteins were removed from the lower phase. Therefore, the ATPS proved to be a very useful method as a first step in the purification of enzymes from red algae.

Mapping of functional sites on the primary structure of the contractile tail sheath protein of bacteriophage T4 by mutation analysis

In order to determine the functional roles of amino acid residues in gp18 (gp: gene product), the contractile tail sheath protein of bacteriophage T4, the mutation sites and amino acid replacements of available and newly created missense mutants with distinct phenotypes were determined. Amber mutants were also utilized for amino acid insertion by host amber suppressor cell strains. It was found that mutants that gave rise to a particular phenotype were mapped in a particular region along the polypeptide chain. Namely, all amino acid replacements in the cold-sensitive mutants (cs, which grows at 37 °C, but not at 25 °C) and the heat-sensitive mutant (hs, lose viability by incubation at 55 °C for 30 min) except for one hs mutant were mapped in a limited region in the C-terminal domain. On the other hand, all the temperature-sensitive mutants (ts, grow at 30 °C, but not at 42 °C) and carbowax mutants (CBW, can adsorb to the host bacterium in the presence of high concentrations of polyethylene glycol, where wild-type phage cannot) were mapped in the N-terminal protease-resistant domain, except for one ts mutant. The results suggested that the C-terminal region of gp18 is important for contraction and assembly, whereas the N-terminal protease-resistant domain constitutes the protruding part of the tail sheath.

Distribution of Macropores in Silica Particles Prepared by Using Multiple Emulsions

The distribution of macropores in silica particles prepared by the hydrolysis and condensation of TEOS in a hexane/water/decyl alcohol (O 1/W/O 2) multiple emulsion was investigated. To stabilize the emulsion structure, hydroxypropyl cellulose (HPC) was added into the O 2 phase and polyethylene glycol (PEG) was added into the water phase. Without HPC, the particles have an irregular shape and hardly have particulate forms. As the concentration of HPC increases, the shape of particles becomes more and more spherical and the size decreases. The size of silica particles was varied from 5 to 1 μm as the concentration of HPC increased from 0.5 to 0.7 wt%. The number and size of the macropores in silica particles were affected by PEG polymer concentration. With the variation in the concentration of PEG, macropores in silica particles were located at the surface of or inside the particles. At high concentrations of PEG, the macropores in particles were located inside the particles, but at low concentrations of PEG the macropores were located at the surfaces of particles. Interestingly, the particles of dimpled surfaces were formed when the molar ratio of water to TEOS ( R w) was 4.0 and the concentrations of PEG and HPC were 2.0 and 0.7 wt% respectively. The surface areas of dimpled silica particles and completely spherical particles, measured by the BET method, were 409 and 433 m 2/g respectively.

Vapor diffusion, nucleation rates and the reservoir to crystallization volume ratio.

In a classical vapor diffusion crystallization, the protein solution is mixed in a 1:1 ratio with the reservoir solution, containing one or more precipitant species, after which the two are placed in an enclosed chamber. As the vapor pressure is lower for the reservoir solution, due to its higher solute concentration, there is a net transfer of water through the vapor phase from the protein droplet to the reservoir. In theory, the initial conditions in the droplet are such that the protein is in either a metastable or undersaturated state with respect to crystal nucleation. The loss of water serves to both concentrate the protein and the precipitant concentrations within the drop, bringing the protein past the metastable point to nucleation. The equilibration rate is a function of the precipitant(s) used, their concentration, the temperature, the distance between the two surfaces, and the droplet to reservoir volume ratio. For a given reservoir volume smaller droplets equilibrate faster, the rate being inversely linear with the droplet volume. In attempts to maximize the number of crystallization trials, and as crystals in the 100 - 200 micro m size range are sufficient, it has currently become standard practice to use starting droplet volumes of 2 - 4 micro l, with reservoir volumes typically in the 200 to 500 micro l range. The equilibration rates are maximized, and for most common salt concentrations and higher concentrations of polyethylene glycol (PEG) and 2-methyl-2,4-pentanediol (MPD) one can reasonably estimate that equilibration has occurred within 3 to 6 days at room temperature. Crystals appearing after this time are essentially grown under batch conditions. We experimentally find that altering the reservoir to droplet volume ratio, by changing the reservoir volume, from 50:1 (high ratio) to 5:1 (low ratio), on average increases the equilibration time by approximately 50 % when tested with solutions of 50% MPD, 1.5 M NaCl, or 30 % PEG 400. However, experiments with two proteins, chicken egg white lysozyme and concanavalin a, showed an unexpected trend of slightly faster nucleation and larger crystals in the lowest ratio experiments.

X-ray structure of junctional adhesion molecule: structural basis for homophilic adhesion via a novel dimerization motif.

Junctional adhesion molecules (JAMs) are a family of immunoglobulin-like single-span transmembrane molecules that are expressed in endothelial cells, epithelial cells, leukocytes and myocardia. JAM has been suggested to contribute to the adhesive function of tight junctions and to regulate leukocyte trans migration. We describe the crystal structure of the recombinant extracellular part of mouse JAM (rsJAM) at 2.5 A resolution. rsJAM consists of two immunoglobulin-like domains that are connected by a conformationally restrained short linker. Two rsJAM molecules form a U-shaped dimer with highly complementary interactions between the N-terminal domains. Two salt bridges are formed in a complementary manner by a novel dimerization motif, R(V,I,L)E, which is essential for the formation of rsJAM dimers in solution and common to the known members of the JAM family. Based on the crystal packing and studies with mutant rsJAM, we propose a model for homophilic adhesion of JAM. In this model, U-shaped JAM dimers are oriented in cis on the cell surface and form a two-dimensional network by trans-interactions of their N-terminal domains with JAM dimers from an opposite cell surface.

Macroprolactin and the Roche Elecsys Prolactin Assay: Characteristics of the Reaction and Detection by Precipitation with Polyethylene Glycol

Prolactin occasionally is present in serum in a macromolecular complex. The most common form is macroprolactin, an antibody-antigen complex of prolactin (PRL) and immunoglobulin G with a molecular mass of 150–170 kDa (1)(2)(3)(4). The PRL component remains reactive (to various degrees) in immunoassays for PRL (5)(6)(7), and macroprolactin is cleared more slowly than PRL from the circulation, leading to apparent hyperprolactinemia (8). Macroprolactin is bioactive in vitro but has minimal bioactivity in vivo, probably because of the failure of the high-molecular mass complex to cross the capillary membrane to reach target PRL receptors (9). Hyperprolactinemia attributable to macroprolactin may cause diagnostic confusion and lead to inappropriate treatment, and it is important that laboratories characterize the response of their assay to macroprolactin and identify macroprolactin when this is a cause of hyperprolactinemia (1)(5). The Wallac Delfia immunofluorometric PRL assay reacts strongly with macroprolactin, and this response is well characterized (5)(6)(10)(11). High concentrations of polyethylene glycol (PEG) precipitate macroprolactin from serum, and this principle has been used in a screening test for the presence of macroprolactin validated with the Delfia assay (5). We studied the reaction of the PRL assay on …

Sensitive thyroid-stimulating antibody assay in whole serum containing five percent polyethylene glycol using porcine thyroid cells.

Previously we reported that the amounts of cyclic adenosine monophosphate (cAMP) production by polyethylene glycol (PEG) 22.5% precipitated fraction (PF) (crude immunoglobulin G [IgG]) from thyroid-stimulating antibody (TSAb)-positive serum were higher than those by PEG 12.5% PF, and that PEG (5%) augmented affinity purified TSAb-IgG-stimulated cAMP production in porcine thyroid cells (PTC) assay. In the present work, we studied sensitive TSAb assay using whole sera in the presence of high PEG concentrations in PTC assay. cAMP produced by TSAb-positive serum increased in proportion to serum amounts up to 0.05 mL, but gradually decreased in 0.075 mL. The maximal augmentative effect of PEG on TSAb-positive serum (0.05 mL)-stimulated cAMP production was found in 5% PEG (final). Thus, TSAb assay using whole serum (0.05 mL) in the absence of 5% PEG (serum method) and sensitive TSAb (sTSAb) assay using whole serum (0.05 mL) in the presence of 5% PEG (serum plus 5% PEG method) were performed. The sensitive thyroid-stimulating antibody (sTSAb) activities of Graves' sera showed significantly higher (twofold to sevenfold) compared to simple TSAb activity with sera. sTSAb and TSAb activities were positive in 91% (29/32) and 47% (15/32) of untreated Graves' patients with hyperthyroidism. The sTSAb activities by serum plus 5% PEG method were higher than that by PEG 12.5% precipitated fraction (PF) from test serum (0.2 mL) in many Graves' sera, but lower than that by PEG 22.5% PF from test serum (0.2 mL). PEG (5%) did not augment cAMP produced by high TSH serum (127-210 mU/L) in thyroiditis chronica. sTSAb activity was negative in adenomatous goiter, subacute thyroiditis, and thyroid cancer. sTSAb activity was also negative in TSH stimulation blocking antibody (TSBAb)-positive hypothyroidism (during thyroxine [T4] treatment), but was positive in Graves' sera with coexistence serum of TSAb and TSBAb because of augmentative effect of 5% PEG on TSAb activity. This assay in whole serum (0.05 mL) containing 5% PEG is less sensitive than sensitive TSAb assay using PEG 22.5% PF from test serum (0.2 mL), but this method can be available clinically as routine TSAb assay using whole serum because of the technical simplicity.

Germination, seedling growth, some organic solutes and peroxidase expression of different Vicia faba lines as influenced by water sterss

The effect of water stress on the germination, seedling growth, organic solutes, peroxidase pattern and peroxidase activity of different Vicia faba lines was studied. Studies on germination in polyethylene glycol and in soil indicated that lines such as Line 2/4 which were able to germinate under water stress caused by high concentrations of polyethylene glycol, were also able to germinate and grow in soil with a low water content. While the fresh and dry masses of all the lines were markedly decreased as the water stress level increased, Line 2/4 exhibited higher dry matter than the other lines tested. Pigment contents were more or less unchanged in some lines (102, 159 and 2/4) but increased in others (67 and 103) as the stress level increased. In general, the soluble sugar, soluble protein, free amino acid and proline contents in the shoots and roots of all the tested lines progressively increased as the stress level increased. These values were higher in the plant shoots than in the roots except for Line 2/4, which was the only one that could be grown at 30 % field capacity, and which accumulated soluble sugars and free amino acids in the roots rather than in the shoots Differences in the peroxidase (POX) pattern were found among the roots and shoots of the tested lines. Under drought stress, the number and staining intensity of the POX bands as well as the POX activity were lower in the shoots than in the corresponding unstressed control plants, especially in the sensitive line (159). In the plant roots, while the number of peroxidase isoenzymes and peroxidase activity were reduced in the sensitive line, they were unaffected in the resistant line (2/4).

A light and X-ray scattering study of the acid catalyzed silica synthesis in the presence of polyethylene glycol

Acid catalyzed silica sol–gel reactions were studied by means of small angle X-ray scattering (SAXS) and dynamic light scattering (DLS). Emphasis was given as to how different concentrations and molecular weights of polyethylene glycol (PEG) influence the fractal dimension ( d f) and particle size distribution during and after the sol–gel reaction. From these measurements a reaction mechanism was determined for both stable and phase separated samples. The structure the material attained was dependent of the reaction mechanism. Both high and low concentrations of PEG produced stable reactions. At higher concentrations steric stabilization of the sol occurred. The mechanism for the stable samples was determined to be diffusion limited cluster–cluster aggregation (DLCCA), reaction limited cluster–cluster aggregation (RLCCA) and reaction limited cluster–cluster aggregation with rearrangements, depending on the molecular weight and concentration of PEG and the time of reaction. Bridging flocculation occurred between the organic and inorganic polymers in the phase separated samples, but only after the particles had attained a specific size. Lower fractal dimensions were observed for these samples, because the reaction did not follow a percolation growth mechanism.

Strontium and cesium extraction into hydrocarbons using alkyl cobalt dicarbollide and polyethylene glycols

The extraction of strontium and cesium ions from high ionic strength acid, base, and salt solutions into an organic extractant consisting of alkyl cobalt dicarbollide and polyethylene glycol (PEG) in diethylbenzene was investigated. Adding hexaethylene glycol or PEG-400 improved the strontium extraction ≥100-fold, while cesium extraction was decreased at high PEG concentrations. The extractions are rapid and selective, even in the presence of molar concentrations of sodium ion, suggesting that alkyl cobalt dicarbollide extractants are useful for the treatment of alkaline nuclear wastes. A method for the synthesis of tetra-n-hexyl(cobalt dicarbollide) is described.

Electromigration behavior of metal ions in the presence of complexing polymer

Electromigration behavior of metal ions in the presence of high concentrations of polyethylene glycol as a complexing agent was investigated under acidic non-buffered conditions. Simulation of the isotachophoretic steady state of the system containing the neutral polymer was performed. Both the complexation and the influence of viscosity on the electrophoretic mobility were taken into account. Good agreement between the calculated results and the experimentally obtained values was achieved. Based on the theoretical model, a new approach for the estimation of polymer–metal stability constants from experimental isotachophoretic data was proposed. Stability constants of Li +, Na +, Cs +, Mg 2+, Sr 2+, Mn 2+, Co 2+, Ni 2+, Zn 2+, Pb 2+, Lu 3+ and Y 3+ ions with polyethylene glycol were determined.