Utilization of Ion-Exchange Resins

The preparation of the column is illustrated by a routine established for the isolation of small amounts (up to 1 mg) of bile acids and conjugates from biological fluids such as blood (20). About 5 ml of the anion-exchange resin is pipetted into a chromatographic column 1.0 cm in diameter. The resin is washed with 50 ml of 1 jV NaOH and 50 ml of 1 A NaOH in 80% ethanol, followed by distilled water until the effluent is neutral. The column is now ready for use. 

TABLE IV. Recovery of C-labeled Bile Acid Conjugates from Dowex 1 (31)  

In addition to the anion exchangers, cation-exchange resins can also be usefully employed in bile acid work. Thus columns of a strong cation-exchange resin (Dowex-50, 2% cross-linked, 50-100 mesh, J.T. Baker Chemical Co.) have been used in the hydrogen form to purify extracts of bile acids prepared from biological materials (2, 30). Prior to use the resin is extracted 

The ion-exchange celluloses and ion-exchange cross-linked dextrans (Sephadex derivatives) have received only limited attention in bile acid work 

The extracted anionic lipid is removed from the amine by a second ion-exchange procedure. The solvent is evaporated from the pooled extracts and the residue is dissolved in ethanol-water 1 1. The solution is passed over a cation-exchange column that is in the hydrogen form and that has been packed in the same solvent mixture. The amine is quantitatively bound, the extracted lipid passes through the column and may be quantitatively recovered from the eluent, which, however, also contains hydrochloric acid because of the liberation of hydrogen ions from the resin by the amine cations. The cation-exchange resin Biorad AG-1 (California Corporation for Biochemical 

---

Batch operation The utilization of ion-exchange resins to treat a solution in a container wherein the removal of ions is accomplished by agitation of the solution and subsequent decanting of the treated liquid. 

Column operation Conventional utilization of ion-exchange resins in columns through which pass, either upflow or downflow, the solution to be treated. 

The synthetic utility of ion exchange resins in combinatorial chemistry has been demonstrated by the use of a basic polymeric base PTBD (l,5,7-triazabicydo[4.4.0]dec-5-ene) 26 in a series of O- and N-alkylation experiments (Scheme 7) [15]. For example, deprotonation of the phenol 27 with this polymeric base PTBD 26 gave the ionic polymeric species 28 which contained the more nucleophilic phenolate. Addition of the 2-bromo aryl ketone 29 gave the aryl ether 30 in reasonable yield and in high purity (Scheme 7). The basic polymeric scavenger PTBD 26 removed all the unwanted HBr produced within the reaction mixture (in the form of 31) and advantageously eliminated the need for an aqueous extractive work-up procedure. 

Serious thought and a considerable amount of effort have been devoted to the utilization of ion-exchange resins in the sugar industry. Some success has been achieved in the beet industry, but the situation is much less certain in cane-sugar production. The principal objectives are the retention by the resins of the ionic (organic and inorganic) impurities and the maximum recovery of sucrose. 

Comar, D. Utilization of Ion Exchange Resins In Thyroid Physiology. Bull. Inform. Scl. Tech. (Paris), No. 85, 41 (1964). (In French). 19 11273... 

I 1. IwASHiNA, S. Studies on the utilization of ion exchange process in sugar refining. I rtV. On the physical strength of ion exchange resins. Proc. Res. Soc. Japan Sugar Refiners Technologists 7, 74 (1958). 

This is not to say that more highly ionized polymers, such as conventional polyelectrolytes, are not of technological importance and interest. In fact, just the opposite is true. Polyelectrolytes have historically been utilized as ion-exchange resins, but a number of novel applications such as cements, gels, and encapsulation membranes are under development. Several applications of these materials, such as polyelectrolyte complexes and ionic biopolymers, are also included in this review. 

Sample cleanup procedures can reduce biological background m cases of trace analyses. However, cleanup procedures utilizing impure ion exchange resins and impure organic solvents may actually add contamination to the analytical sample. 

Phenomena of dimensional changes of ion exchange resins are widely known These changes are particularly pronounced if monovalent ions are exchanged with polyvalent ions. Since these changes are reversible, ion exchange has been sometimes utilized in chemomechanical systems... 

The ratio of reactants had to be controlled very closely to suppress these impurities. Recovery of the acrylamide product from the acid process was the most expensive and difficult part of the process. Large scale production depended on two different methods. If soHd crystalline monomer was desired, the acrylamide sulfate was neutralized with ammonia to yield ammonium sulfate. The acrylamide crystallized on cooling, leaving ammonium sulfate, which had to be disposed of in some way. The second method of purification involved ion exclusion (68), which utilized a sulfonic acid ion-exchange resin and produced a dilute solution of acrylamide in water. A dilute sulfuric acid waste stream was again produced, and, in either case, the waste stream represented a... 

Miscellaneous. Hydrochloric acid is used for the recovery of semiprecious metals from used catalysts, as a catalyst in synthesis, for catalyst regeneration (see Catalysts, regeneration), and for pH control (see Hydrogen-ION activity), regeneration of ion-exchange (qv) resins used in wastewater treatment, electric utiUties, and for neutralization of alkaline products or waste materials. In addition, hydrochloric acid is also utilized in many production processes for organic and inorganic chemicals. 

It is possible to extract or remove ionic species, both anions and cations, from soil using ion exchange resins. Both anion and cation exchange resins have been used as well as combinations of the two. Resins can be added to the soil and mixed, or they can be contained in a bag (Procedure 11.11), on a strip, or in capsules buried in soil. Mixing resins with soil allows for more intimate contact with soil and with the soil solution. However, one is faced with separation of the resin from soil at the end of some extraction time. Resins in bags, on strips, or as capsules can easily be removed from soil. However, the resins do not have as intimate contact with soil in this procedure. Good relationships between all these methods and standard extraction methods have been obtained and all approaches have found utility in determining the amounts of various ions in soil. 

---