Organic ions

Organic compounds that are ionic or that become ionic at certain pH values can be isolated selectively from neutral organic compounds by SPE with ion-exchange materials [7]. Amines become protonated cations in acidic solution and are retained by a short cation-exchange column in the form. Actually, the cation exchanger or exchanges can convert a neutral amine to the protonated cation. [Pg.194]

Neutral organic compounds that cannot exist as cations may be retained by physical adsorption but can be washed off the cation exchange colunm by a brief rinse with an organic solvent. The amine cation can then be eluted from the column with a 1 M solution of trimethylamine in methanol. The trimethylamine converts the amine cation to the free amine which is no longer retained by the cation exchanger. Because of its volatility, trimethylamine is easily removed from the eluate. After acidification, the sample amines can be separated by cation chromatography. [Pg.194]

The cation exchange resin used in this operation should be a raacroporous, rather than a microporous, polymer to minimize physical adsorption. An intermediate [Pg.194]

No mechanistic aspects of organic chemistry (or, for this reason, any reaction intermediates) were ever mentioned by Zemplen in his lectures or writings, nor did he consider or accept their existence. I never heard him mention the names of Meerwein, Ingold, Robinson, or any other pioneers of the mechanistic electronic theory of organic chemistry. The possible role of organic ions was similarly never mentioned. He was. [Pg.55]

Capillary zone electrophoresis provides effective separations of any charged species, including inorganic anions and cations, organic acids and amines, and large biomolecules such as proteins. For example, CZE has been used to separate a mixture of 36 inorganic and organic ions in less than 3 minutes.Neutral species, of course, cannot be separated. [Pg.606]

PhenoHc-based resins have almost disappeared. A few other resin types are available commercially but have not made a significant impact. Inorganic materials retain importance in a number of areas where synthetic organic ion-exchange resins are not normally used. Only the latter are discussed here. This article places emphasis on the styrenic and acryHc resins that are made as small beads. Other forms of synthetic ion-exchange materials such as membranes, papers, fibers (qv), foams (qv), and Hquid extractants are not included (see Extraction, liquid-liquid Membrane technology Paper.). [Pg.371]

Reverse osmosis (hyperhitration or nanohltration) Liquid Liquid 10-70 Porous/ nonpoTOus Desalination, salts, organics, ions heavy metals... [Pg.263]

A complete set of intermolecular potential functions has been developed for use in computer simulations of proteins in their native environment. Parameters have been reported for 25 peptide residues as well as the common neutral and charged terminal groups. The potential functions have the simple Coulomb plus Lennard-Jones form and are compatible with the widely used models for water, TIP4P, TIP3P and SPC. The parameters were obtained and tested primarily in conjunction with Monte Carlo statistical mechanics simulations of 36 pure organic liquids and numerous aqueous solutions of organic ions representative of subunits in the side chains and backbones of proteins... [Pg.46]

McLafferty, F. W., Mass Spectrometry of Organic Ions, Academic... [Pg.234]

Exchange of organic ions. Although similar principles apply to the exchange of organic ions, the following features must also be taken into consideratioa... [Pg.192]

The sizes of organic ions differ to a much greater extent than is the case for inorganic ions and may exceed 100-fold or even 1000-fold the average size of inorganic ions. [Pg.192]

Selectivity of sorption of organic ions by crosslinked polyelectrolytes in competition with small ions, in particular with metal ions, should be considered on the basis of the analysis of thermodynamic relationships of ion exchange. [Pg.17]

In the bonding of complex organic ions by densely crosslinked polyelectrolyte, not all active centers of ion exchanger are accessible to counterions [54]. For these systems Eq. (3.4) becomes... [Pg.19]

The thermodynamic analysis of the selectivity of ion exchange with the participation of ions of quaternary ammonium bases [56--58] has shown that an increase in bonding selectivity, when metal ions are replaced by organic ions, which is usually accompanied by an increase in entropy of the system (Table 5). It follows from Table 5 that a drastic increase in bonding selectivity upon passing to a triethylbenzylammonium counterion (the most complex ion) is due to a considerable increase in the entropy of the system. [Pg.19]

The thermodynamic analysis of these systems played an important role in the interpretation of these data and of the high selectivity. It was found that selective sorption of complex organic ions is accompanied by an increase in the entropy of the system (Table 6). [Pg.20]

A comparison of the effects of increasing selectivity of sorption of organic counterions and the entropy control of the replacement of small ions by large organic ions in CP is a rational explanation of these phenomena. [Pg.20]

Fig. 15. Cooperative effect of bonding of organic ions on Biocarb-T biosorbent A. 0.1 N NaCl in water B, 0.1 N NaCl in methanol. For l) novocain, 2) oleandomycin and 3) oxytetracycline...

The interpretation of the relationships obtained here is based on the same principles of polyfunctional interaction between CP and organic ions which are considered in sections 3.1-3.3. The dispersion of CP grains to a certain size (1-10 pm) yields particles retaining the ability of polyfunctional interaction with organic ions. Simultaneously with increasing dispersion, the mobility of elements of the crosslinked structure also increases, which favors additional interaction. Further dispersion of CP (d 0.1 pm) gives so weak networks that the spatial effect of polyfunctional interaction with organic ions drastically decreases similar to linear polyelectrolytes [64]. [Pg.33]

It should be noted that the flocculation effect produced by microdisperse forms of CP is applicable not only to protein solutions but also to solutions containing various organic ions. [Pg.33]

Mass-Exchange Kinetics of Organic Ions on Crosslinked Polyelectrolytes... [Pg.38]

In order to prove the limitation of the process by quasi-diffusion in the grain, it is most convenient to carry out experiments with phase contact interruption [107], For the sorption of organic ions after this interruption and the restoration of the contact after a certain period of time, the dependence usually the shape of... [Pg.39]

For slow diffusion of organic ions, one of the most suitable methods for the determination of quasi-diffusion in the grain is the use of the calculation of mean sorption time t [108]... [Pg.40]

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