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[Ion exchange resins].

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Ion Exchange Resins↗
PubMed1994

A simple method for classification of antibiotics using ion exchange resins added to agar plates.

Using two different ion-exchange resins (Dowex 50W-X4 as cation and Dowex 1-X4 as anion) added directly to assay plates seeded with Bacillus subtilis or Micrococcus luteus, the size of the inhibitory zone produced by 36 antimicrobial agents around a disc or cup was characterized into various types, such as acidic, basic or amphoteric. An increase of the inhibition zone following addition of 15% Dowex 50W-X4 was evident in penicillins except for ampicillin and penicillin-G, and polyethers. Aminoglycosides, macrolides and colistin, lincomycin, and sulphonamides on assay medium treated with Dowex 1-X4 showed a similar effect on the inhibition zone. Tetracyclines, virginiamycin, oxolinic acid and furazoridone revealed no effects on the inhibition zone with either of the resins. These antibiotics could be divided into various groups on the basis of their chemical structure. This simple and rapid method may be useful for routine laboratory testing of residual antibiotics in meat.

Anion Exchange Resins↗
PubMed2003

Kinetics of removal of chromium from water and electronic process wastewater by ion exchange resins: 1200H, 1500H and IRN97H.

The removal of chromium from aqueous solution by an ion exchange resin is described. Ion exchange resins 1200H, 1500H and IRN97H show a remarkable increase in sorption capacity for chromium, compared to other adsorbents. The adsorption process, which is pH dependent show maximum removal of chromium in the pH range 2-6 for an initial chromium concentration of 10mg/l. The metal ion adsorption obeyed linear, Langmuir and Freundlich isotherms. The adsorption of chromium on these cation exchange resins follows first-order reversible kinetics and pseudo-first-order kinetics. The intraparticle diffusion of chromium on ion exchange resins represents the rate-limiting step. The uptake of chromium by the ion exchange resins was reversible and thus have good potential for the removal/recovery of chromium from aqueous solutions. We conclude that such ion exchange resins can be used for the efficient removal of chromium from water and wastewater.

Adsorption↗
PubMed2006

Chromate (CrO(4)(2-)) and copper (Cu2+) adsorption by dual-functional ion exchange resins made from agricultural by-products.

Ion exchange resins commonly have a single functionality for either cations or anions. Resins that have a dual functionality for both cations and anions are uncommon. The objective of this study was to create dual-functional ion exchange resins derived from soybean hulls, sugarcane bagasse and corn stover. Dual-functional resins were prepared by two separate two-step processes. In the first two-step process, by-products were reacted with a solution of citric acid in order to impart additional negative charge, and then reacted with the cross-linking reagent dimethyloldihydroxyethylene urea (DMDHEU) and a quaternary amine (choline chloride) to add positive charge to the lignocellulosic material. In the second two-step process, the order of reaction was reversed, with positive charge added first, followed by the addition of negative charge. These combined reactions added both cationic and anionic character to the by-products as evidenced by the increased removal from solution of copper (Cu(2+)) cation and the chromate (CrO(4)(2-)) anion compared to unmodified by-products. The order of reaction appeared to slightly favor the functionality that was added last. That is, if negative charge was added last, the resulting resin sequestered more copper ion than a comparable resin where the negative charge was added first and vice-versa. Cu(2+) and CrO(4)(2-) were used as marker ions in a solution that contained both competing cations and anions. The dual-functional resins adsorbed as much as or more of the marker ions compared to commercial cation or anion exchange resins used for comparison. None of the commercial resins exhibited dual-functional properties to the same extent as the by-product-based resins.

Adsorption↗
PubMed1981

Evaluation of ion exchange resins and various enzymes in thiamine analysis.

Four ion exchange resins and 9 enzyme preparations are evaluated for use in the official AOAC thiamine method because Decalso and Clarase or Mylase P either are no longer available or are available in a form that is not suitable for use in the assay. The enzymes are prepared in the same manner described for Clarase or Mylase P in the AOAC method and are compared with Clarase T300 for their effectiveness in releasing thiamine from thiamine phosphate, and their ability to produce similar results on samples. Rhozyme S is 90-100% as effective as Clarase T300 in both of these respects. The other enzymes tested were not satisfactory. Further study is necessary because Rhozyme S also is no longer manufactured. The ion exchange resins are prepared for use in the manner described for Decalso in the AOAC method. Recoveries of thiamine range from 95 to 100%, using Bio-Rex 70 (hydrogen form) ion exchange resin. The other resins tested were not satisfactory.

Enzymes↗
PubMed1998

Effect of ion exchange resins on the drug release from matrix tablets.

Ion exchange resins were incorporated into hydroxypropylmethylcellulose (HPMC) matrix tablets to modify the release of oppositely charged drugs. The drug release from HPMC tablets containing drug-resin complexes was significantly slower than from HPMC tablets containing drug without resin. A physical mixture of drug and ion exchange resin (cationic drug, propranolol HCl, with the cation exchange resin, Amberlite IRP 69, or the anionic drug, sodium diclofenac, with the anion exchange resin, cholestyramine (Duolite ATP-143)) resulted in almost the same drug release as tablets containing preformed drug-resin complexes. Upon contact with the dissolution medium, a gel layer formed rapidly around the solid tablet core and the complex between the drug and the resin formed in situ within the gelled regions. No effect of pH of the dissolution medium (0.1 N HCl or pH 7.4 phosphate buffer) or resin counterion was observed with the strong cation exchanger, Amberlite IRP 69. The resin was dissociated at both pH-values, allowing drug binding. With the weak cation exchange resin, Amberlite IRP 88, in situ complex formation and retardation was only observed in pH 7.4 buffer but not in 0.1 N HCl because of the non-ionization of the carboxyl groups. The drug release depended also on the amount and particle size of the resin particles and the type of carrier. The use of smaller resin particles eliminated the burst release seen with larger resin particles. Upon comparing different carrier materials, a rapid formation of the gel layer was important for the in situ complex formation. The drug release was in the order of Gelucire 54/02 (glyceryl palmitostearate) > polyethylene oxide 400K > HPMC K15M.

Adrenergic beta-Antagonists↗