CM cation exchangers

DEAE (anion exchange) and CM (cation exchange) are fully charged over a narrower pH range (pH 2-9 and pH 6 - 10, respectively), but give alternative selectivities for separations. 

Protons associated with water molecules have been located in a number of systems including sodaUte [86,87], and NAT [88], ABW [74,77] and ANA framework [89] gallosilicates. Hydroxylic proton pomticms have been determined in sodalite [86,90] and in a steam-treated zeolite rho [91,92]. The flexibility of the RHO-framewoik has also been further probed by PND studies cm cation-exchanged matoials [93,94] and cm ammonium-ion exchanged and heat-treated zeolite rho [95]. 

FIGURE 15.18. Electrolyzers for splitting sodium sulfate. AM Anion-exchange membrane CM Cation-exchange membrane. 

Hydrina electrolyzer CM Cation-exchange membrane DIA Diaphragm. 

Eig. 5. Pressure drop as affected by resin type, flow rate, and temperature, where A, B, and C, correspond respectively to acryUc strong base anion exchanger (Amberlite IRA-458), styrenic strong base anion exchanger (Amberlite IRA-402), and styrenic strong acid cation exchanger (Amberlite IR-120), all at 4°C. D represents styrenic strong acid cation resin (Amberlite IR-120) at 50°C (14). To convert kg/(cm -m) to lb/(in. -ft), multiply by 4.33 to convert... 

Example 8 Estimation of Rate Coejficient Estimate the rate coefficient for flow of a 0.01-M water solution of NaCl through a bed of cation exchange particles in hydrogen form with e = 0.4. The superficial velocity is 0.2 cm/s and the temperature is 25 C. The particles are 600 im in diameter, and the diffusion coefficient of sodium ion is 1.2 X 10 cmVs in solution and 9.4 X 10 cmVs inside the particles (of. Table 16-8). The bulk density is 0.7 g dry resin/cnd of bed, and the capacity of the resin is 4.9 mequiv/g dry resin. The mass action eqiiihbrium constant is 1.5. 

The tetramethylammonium salt [Me4N][NSO] is obtained by cation exchange between M[NSO] (M = Rb, Cs) and tetramethylammonium chloride in liquid ammonia. An X-ray structural determination reveals approximately equal bond lengths of 1.43 and 1.44 A for the S-N and S-O bonds, respectively, and a bond angle characteristic bands in the IR spectrum at ca. 1270-1280, 985-1000 and 505-530 cm , corresponding to o(S-N), o(S-O) and (5(NSO), respectively. Ab initio molecular orbital calculations, including a correlation energy correction, indicate that the [NSO] anion is more stable than the isomer [SNO] by at least 9.1 kcal mol . ... 

Column. 15.0 cm x 4.6 mm, packed with a 5/on silica SCX (strong cation exchanger) bonded phase. 

Fig. 3. Cation-exchange chromatography of protein standards. Column poly(aspartic acid) Vydac (10 pm), 20 x 0.46 cm. Sample 25 pi containing 12.5 pg of ovalbumin and 25 pg each of the other proteins in the weak buffer. Flow rate 1 ml/min. Weak buffer 0.05 mol/1 potassium phosphate, pH 6.0. Strong buffer same +0.6 mol/1 sodium chloride Elution 80-min linear gradient, 0-100% strong buffer. Peaks a = ovalbumin, b = bacitracin, c = myoglobin, d = chymotrypsinogen A, e = cytochrom C (reduced), / = ribonuclease A, g = cytochrome C (oxidised), h = lysozyme. The cytochrome C peaks were identified by oxidation with potassium ferricyanide and reduction with sodium dithionite [47]...

Macrochromatographlc Methods. These procedures use cation exchangers, such asAmberllte-IRC-50, carboxymethyl-Cellulose (CMC) and carboxymethyl-Sephadex (CMS), and the anion exchangers diethylamlnoethyl-(DEAE)-Cellulose and DEAE-Sephadex. 

The dialysed sample was fractionated by cation exchange chromatography. A 40-50 ml sample was applied to a CM-Sepharose CL-6B column (1.5 x 15 cm). Unbound proteins were removed with 50 mM MES pH 6.8, 1 mM DTT, and the bound proteins were eluted with an increasing NaCl gradient from 0 - 0.4 M NaCl in a total volume of 500 ml. The flow was 25 ml/h and fractions of 8.33 ml were collected. The protein profile was measured at 280 nm. 

AE was purified from orange peels. After homogenization, precipitation with 30 - 60% (NH4)2S04 followed by dialysis, the sample was applied to a cation exchange column (CM-Sepharose CL-6B). AE binds strongly to a cation exchange column material at pH 6.8... 

Figure 5 Separation of pharmaceuticals, including amines, on strong cation exchange. Column 0.46 x 15 cm Merckosorb SI-60-SCX, 5 p. Eluent 50 mM aqueous ammonium formate-10% ethanol, pH 4.8. Flow 1 ml/min. Temperature 50°C. The peaks are (1) aspirin, (2) paracetamol, (3) phenacetin, (4) caffeine, (5) phenylephrine, (6) salbutamol. (Reproduced with permission of Elsevier Science from Cox, G. B., Loscombe, C. R., Slucutt, M. J., Sugden, K., and Upheld, J. A., /. Chromatogr., 117, 269, 1976).

Valproic acid was determined in tablets and plasma using ion-chromatography [29], The extract was injected onto a column (6.5 cm x 6 mm) of Dionex ICE separator resin fitted with a guard column of Aminex cation exchange resin and operated with aq. 0.5 mM C02 as mobile phase (0.7 mL/min) and conductivity detection. For tablets, the calibration graph was rectilinear for 0.2-25 pg/mL with limit of detection of 50 pg/mL. For plasma, the response was linear for 50-200 pg/mL and limit of detection was 2 pg/mL. 

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