Carboxyl Cationic

Humic acids are alkaH-extractable materials and total humic acid content is a term that refers to the humic acid content of coal that has had its carboxylate cations removed with sodium pyrophosphate. Values for some typical AustraHan brown coals range from 24—92% (13). Treatment of lignitic coals with mineral acid to release the alkaH and alkaline cations may dissolve up to 20% of the coal. The naturally moist coals are slightly acidic and have a pH of 3.5—6.5. 

The assumption of the association of Hb in the pores of carboxylic cation exchangers has been advanced in Ref. [47] on the basis of electron microscopy at the maximum filling, almost all the pore surface is filled with Hb associates which are ordered star-shaped structures. Interprotein interaction in the adsorption immobilization of enzymes have been reported in Refs. [74, 75]. 

Fig. 28. Effect of degree of swelling on diffusion coefficient of streptomycin in carboxylic cation exchangers /) KB-4, 2) KFA, J) KB-2, 4) KMDM-6...

Shataeva LK, Kuznetsova NN, Elkin GE (1979) Carboxylic Cation-Exchangers in Biology, (in Russian) Nauka... 

Ether carboxylate Cation Chain R- Typ. chem. cone. (%) Characterization Label R symbol phrases ... 

Analyses for the Saxitoxins. Early methods for analysis of the saxitoxins evolved from those used for toxin isolation and purification. The principal landmarks in the development of preparative separation techniques for the saxitoxins were 1) the employment of carboxylate cation exchange resins by Schantz et al. (82) 2) the use of the polyacrylamide gel Bio-Gel P2 by Buckley and by Shimizu (5,78) and 3) the development by Buckley of an effective TLC system, including a new solvent mixture and a new visualization technique (83). The solvent mixture, designated by Buckley as "E", remains the best for general resolution of the saxitoxins. The visualization method, oxidation of the saxitoxins on silica gel TLC plates to fluorescent degradation products with hydrogen peroxide and heat, is an adaptation of the Bates and Rapoport fluorescence assay for saxitoxin in solution. Curiously, while peroxide oxidation in solution provides little or no response for the N-l-hydroxy saxitoxins, peroxide spray on TLC plates is a sensitive test for all saxitoxin derivatives with the C-12 gemdiol intact. 

A number of minor components present in commercial neomycin have been separated by column chromatography on a carboxylic cation-exchange resin, Amberlite CG-50 99. The components were eluted from the resin with ammonium hydroxide solution. T.L.C. of the eluent fractions showed the presence of two previously unreported impurities which were then isolated on Dowex 1X2 and tentatively identified using NMR and mass spectrometry. 

Prothrombin (from equine blood plasma). Purified by two absorptions on a barium citrate adsorbent, followed by decomposition of the adsorbents wilh a weak carboxylic cation-exchanger (Amberlite IRF-97), isoelectric pptn (pH 4.7-4.9) and further purification by chromatography on Sephadex G-200 or IRC-50. Finally recrystd from a 1% soln adjusted to pH 6.0-7.0 and partial lyophilisation to ca 1/5 to 1/lOth vol and set aside at 2-5° to crystallise. Occasionally seeding is required.. [Miller Biochemical Preparations 13 49 1971]. 

The scheme for such a process is shown in Fig. 8 where C=Na, B=Sr +, and A=Ca +, and concentrations in the starting solution of this example are 2.5, 0.01, and 0.07 equiv/dm, respectively. The separation has been performed on carboxylic cation exchanger KB-4. Strontium carbonate has been precipitated from the product solutions of SrCl2 and NaCl [24]. 

Scheme 2.3 Addition polymerization synthesis of an acrylic carboxylic cation exchange...

Figure 8.6 A typical alkalinity leakage profile during dealkalization on a weak acid carboxylate cation exchanger...

Elvidge, Proctor, and Baines72 found that oxycellulose used as a carboxylic cation-exchange column would separate phenol and chlorocresol from various alkaloids, including meperidine before determination by ultraviolet spectroscopy. IN H2S04 followed by water was used to elute the phenol and chlorocresol and additional H2S04 eluted the meperidine. This method was devised for the assay of injection formulations. 

Spectroscopic evidence for association through the sharing of carboxylate cations has been reported (37) (the phenomenon is discussed in Chapter 15) for surfactant-acrylic acid copolymer interactions. This dependence on surface carboxylate groups (Figure 17) is not observed in cellulose ether or in HEUR 200 formulations. This observation is made in reviewing all of the data, and probably reflects only the extreme surfactant sensitivity of HEUR 200. 

Several reviewers of this chapter have stressed that the model proposed in Figure 18 is speculative. It is, in the sense that there are so many variables in a coating formulation that no mechanism will be universal (i.e., this mechanism is not being proposed for vinyl-acrylic HEC-stabilized latices). The carboxylate cation ion-dipole interaction with the oxygen atoms of the oxyethylene units is not speculative. Numerous publications other than the one ATR-FTIR (attenuated total reflectance-Fourier transform infrared)... 

The potential of microemulsions for organometaUic-catalyzed hydrogenations in water/scC02 biphasic systems has been assessed using the rhodium-catalyzed hydrogenation of styrene as a common test reaction [Eq. (7)] [31]. The water-soluble Wilkinson complex [RhCl(TPPTS)3] was applied as catalyst precursor together with anionic perfluoropolyether carboxylates, cationic Lodyne A, or nonionic poly-(butene oxide)-b-poly(ethylene oxide) surfactants. The interfacial tension is small in the presence of the supercritical fluid and small amounts of surfactant (0.1-2.0 wt.%) suffice to form stable microemulsions. The droplet diameter of the microemulsions varied between 0.5 and 15 pm and a surface area of up to 10 m was obtained. 

Definition Potassium salt of a low crosslinked carboxylic cation-exchange resin prepared from methacrylic acid and divinylbenzene Properties Wh. to off-wh. free-flowing powd., odorless to faint odor, tasteless pract. insol. in water and in most liqs. 

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