Mixed-bed Ion Exchange Research Articles

Pitfalls in the use of commercial nonionic detergents for the solubilization of integral membrane proteins: Sulfhydryl oxidizing contaminants and their elimination

For studies of isolated integral membrane proteins, nonionic detergents are an essential class of chemicals. A serious handicap, however, is that purified detergents which have been chemically analyzed are not available commercially. One type of contaminant that complicates studies of membrane-bound proteins acts as a sulfhydryl oxidizing agent. We have developed a convenient spectrophotometric assay to detect sulfhydryl oxidizing agents and have examined a number of nonionic detergents frequently used in biochemical studies. The method involves incubation of 1% detergent solutions with a known amount of dithiothreitol for 20 h followed by back-titration of unreacted dithiothreitol with 5,5′-dithiobis(2-nitrobenzoic acid). Many of the detergents assayed were found to contain significant amounts of oxidizing agents. The amount varied between different lots of the detergent and increased upon standing in aqueous solution, presumably due to peroxide formation initiated by light and oxygen. A method for purifying commercial nonionic detergents is proposed in which sulfhydryl oxidizing contaminants are eliminated by reaction with sodium borohydride followed by silica gel column chromatography and passage through a mixed bed ion-exchange resin.

Effects of Acidification on Mobilization of Heavy Metals and Radionuclides from the Sediments of a Freshwater Lake

Large (10 m) diameter enclosures were sealed to the sediments in 2–2.5 m of water in Lake 223. Two tubes were held at control pH (6.7–6.8), one was lowered to pH 5.7 and one to pH 5.1, using H2SO4. Aluminum, manganese, zinc, and iron were released from lake sediments at pH 5 and 6. Concentrations of zinc in the overlying water column exceeded 300 μg∙L−1. Radioisotopes of several heavy metals added to the water of the enclosure showed the following: all metals were removed from the water at log-linear rates, with half-times of 5–25 d. Acidification caused several metals to become more soluble, including Fe-59, Co-60, Mn-54, and Zn-65. Solubility of V-48 and Hg-203 decreased with increasing acidity. Acidification also slowed the loss to sediments of Mn-54 and Zn-65. Losses of Ba-133, Se-75, Cs-134, and V-48 were more rapid under acid conditions. The fractions of any isotope retained by a 0.45-μm filter, activated charcoal and mixed-bed ion exchange resin remained constant throughout the experiment at any given pH.Key words: sediment–water interactions, heavy metals, radionuclides, lake acidification

The surface chemistry of polystyrene latices initiated by the persulfate/bisulfite/iron system

A series of polystyrene colloids in water was prepared by emulsion polymerization using the PBI initiator system [persulfate/bisulfite/iron (III)] and SDS surfactant (sodium dodecyl sulfate). In one case no surfactant was used. In some, divinyl benzene was employed as a crosslinking agent. The colloids were purified and converted to the surface acid form by a combination of continuous hollow fiber dialysis and ion exchange. The kinetics of the autocatalyzed hydrolysis of certain surface acid groups, presumably RSO 4H, were determined at 70, 86, and 100°C by conductometric titration. Hydrolysis also occurred during dialysis and ion exchange. A residuum of nonhydrolyzable surface acid, presumably RSO 3H, was always found. Mixed bed ion-exchange resins could be used to clean the colloids only after exhaustive purification, even though separate cation and anion resins appeared always to contaminate the latex surface. Dialysis alone was unsatisfactory.

Characterization of surface charge on polystyrene latices

To get information about the surface charge, potentiometric and conductometric titrations have been carried out on monodisperse latices. Using these methods, strong acidic groups were detected for latices prepared in the presence of strong acid soaps. Similarly, for latices prepared with weak acid soaps, weak acidic groups were observed even after several purifications with mixed-bed ion exchange resins used in a batch procedure. The influence of the soap chain length on the surface charge has been investigated. An increase of the hydrophobic part of the soap leads to higher surface charges. Furthermore, surface charge-ionic strength relationships were established, which allowed us to calculate the surface dissociation constant of the weak acidic groups. The problem of the origin of surface charge has also been considered by comparison between the aforementioned data and information from molecular weight distribution of the polystyrene chains obtained by gel permeation chromatography. Other latices prepared in the same experimental conditions as for emulsion polymerization but without any soap were also studied.

Effect of infusing selected chemical compounds on dentinal fluid movement in the rat.

Intra-arterial infusion of carbamyl phosphate or of carbamyl-DL-aspartic acid into rats on a cariogenic diet greatly stimulated the movement of fluid through the odontoblastic processes. The infusion of sodium cyanate also stimulated fluid movement. Guanidine HCL and L-asparagine were active at higher concentrations. Purifying the urea on a mixed-bed ion exchange resin virtually removed its stimulatory effect on dentinal fluid movement. The action of urea is apparently attributable to contamination with sodium cyanate.

Inhibition of Vascular Blockage and Extension of Vase Life in Cut Roses with an Ion Exchange Column1

Abstract Effects of a mixed bed ion exchange resin column on vascular blockage and vase life were studied in cut roses (Rosa hybrida L. cv. Red American beauty) by measuring blockage rates in excised stem sections and by determining water uptake, fresh weight retention, and longevity of cut roses held in distilled water. The ion exchange column inhibited vascular blockage in excised stem segments. Water uptake and retention of fresh weight of cut roses were enhanced significantly by the ion exchange column treatment, and early wilting, known as “bent neck” was inhibited.

Trace element extraction by mixed ion exchange resins

Mixed-bed ion exchange resins have been employed to extract trace quantities of fission products and other elements from aqueous solutions. A slurry method was used in preference to column extraction and was found to be faster and as efficient. By using a 2:1 ratio of cation to anion resin, the pH of the solution could be kept low enough to minimize colloid formation and beaker adsorption. The pH variation for 1:1 mixtures is found to exhibit several interesting features, including an unexplained, long-period decline in pH value.

Filtration Capacity of Ion Exchange Columns

THE removal of particulate matter from water by mixed bed ion exchange resin columns has recently been the subject of some comment, in particular with regard to the removal of particles of iron1,2 and aluminium3 oxides from nuclear reactor loops containing water. We have been concerned with experiments with very dilute solutions, which necessitate the use of water free of suspended matter, and we have observed that this filtration can be extremely efficient. A simple intensity comparison of scattered light from ‘AnalaR’ water and from water from an ‘Elgastat’ mixed bed demineralizer, 60 cm long × 9 cm diameter, showed that at least 50 times more light was scattered from the ‘AnalaR’ water. The ratio of suspended solids in the two liquids is larger than 50, as there is present a background of scattered light which should be subtracted from the two intensities to obtain a true figure; it is very difficult to distinguish the very small amount of scattered light from the demineralized water from this background illumination.

Removal and Recovery of Cesium-137 from Swimming Pool Reactor Water

A process for recovering cesium-137 from the waterpurification system of a swimming pool reactor is based on the co-crystallization of cesium-137 alum with ammonium alum in aqueous effluents from a mixed-bed ion exchange. The use of an ethyl alcohol medium and a crystallization temperature of 29 deg C enabled recovery of 98 to 100% of the cesium with one precipitation.

New Columnar and Mixed-Bed Ion Exchange Methods for Surfactant Analysis and Purification

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew Columnar and Mixed-Bed Ion Exchange Methods for Surfactant Analysis and PurificationM. E. Ginn and C. L. ChurchCite this: Anal. Chem. 1959, 31, 4, 551–555Publication Date (Print):April 1, 1959Publication History Published online1 May 2002Published inissue 1 April 1959https://doi.org/10.1021/ac50164a028RIGHTS & PERMISSIONSArticle Views120Altmetric-Citations36LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (646 KB) Get e-Alerts Get e-Alerts

Conditioning of d2O in heavy water power reactors

AbstractThis report indicates the problems associated with the maintenance of the purity of the D2O in a pressurized heavy water power reactor and how these problems are handled.In a pressurized water power reactor, impurities will be introduced into the coolant and moderator from the corrosion of the steel system. These impurities are mainly particulate and colloidal in nature. They must be kept to a minimum since when circulated through the reactor they become activated by the neutron flux and when deposited throughout the system they make accessibility for maintenance difficult. Impurities may also be introduced into the water from fuel element ruptures. These also create maintenance problems since they are intensely radioactive.Heavy water systems require a constant guard against the introduction of light water which would degrade the D2O and make the operation of the reactor inefficient or perhaps impossible. The isotopic content of the heavy water must be checked constantly. Upgrading may be required periodically or continuously.The general purity of the water in the reactor is maintained by passing a fraction of the main circulating volume through a by‐pass containing a filter and a mixed bed ion exchange resin column. This column serves to remove ionic impurities as well as acting as an efficient filter itself. It is also used to maintain the pH of the water at the desired level whether neutral or alkaline. In the case of heavy water systems the resin must be deuterized before use to prevent degrading the D2O.

Mixed Bed Ion Exchange for the Removal of Radioactivity

Journal AWWAVolume 49, Issue 8 p. 1085-1102 Article Mixed Bed Ion Exchange for the Removal of Radioactivity H. Gladys Swope, H. Gladys SwopeSearch for more papers by this author H. Gladys Swope, H. Gladys SwopeSearch for more papers by this author First published: 01 August 1957 https://doi.org/10.1002/j.1551-8833.1957.tb16910.xCitations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume49, Issue8August 1957Pages 1085-1102 RelatedInformation

Correction - "Application of Mixed Bed Ion Exchange to Water Purification in Nuclear Reactors"

Correction - "Application of Mixed Bed Ion Exchange to Water Purification in Nuclear Reactors"

Application of Mixed Bed Ion Exchange to Water Purification in Nuclear Reactors

Application of Mixed Bed Ion Exchange to Water Purification in Nuclear Reactors

Paper electrophoresis of streptomycins.

MANNOSIDOSTREPTOMYCIN in some streptomycin preparations is conveniently detected by the paper chromatographic procedure of Winston and Eigen1. In the presence of high concentrations of salts such as in ion-exchange column eluates, or in fermentation broths, this procedure is not applicable: attempts to desalt such solutions, by mixed-bed ion-exchange, electrolytic de-ionization or solvent extraction, have proved unsuccessful. We have found it possible to separate streptomycin, mannosidostreptomycin and allied substances by paper electrophoresis, having developed (independently) a technique similar to that used for new antibiotic broths by Hosoya et al. 2, and King and Doery3.