Mixed bed ion exchanger

Formamide (specific conductance 2 x 10 ohnr cnr ) of low water content was dried by passage through a column of 3A molecular sieves, then deionized by treatment with a mixed-bed ion-exchange resin loaded with H" " and HCONH" ions (using sodium formamide in formamide)[Notley and Spiro J Chem Soc (B) 362 1966. ... 

Phospholipids. For the removal of ionic contaminants from raw zwitterionic phospholipids, most lipids were purified twice by mixed-bed ionic exchange (Amberlite AB-2) of methanolic solutions. (About Ig of lipid in lOmL of MeOH). With both runs the first ImL of the eluate was discarded. The main fraction of the solution was evaporated at 40°C under dry N2 and recryst three times from n-pentane. The resulting white powder was dried for about 4h at 50° under reduced pressure and stored at 3°. Some samples were purified by mixed-bed ion exchange of aqueous suspensions of the crystal/liquid crystal phase. [Kaatze et al. J Phys Chem 89 2565 7955.]... 

FIG. 16-43 Principles of mixed-bed ion exchange, (a) Service period (loading), (b) Backwash period, (c) Caustic regeneration, (d) Acid regeneration. (e) Resin mixing. 

The product is further treated in a degasifier and mixed bed ion exchanger. 

The handling of the biocide supply as the potassium salt rather than in the elemental form circumvented the toxicological and corrosive problems associated with iodine. In addition, the sodium metabisulfite stream is available to reduce the iodine in the product stream prior to demineralization in the mixed bed ion exchanger. 

Soln. A and A should be made from substances of highest available purity and amount should be not more than a monthly consumption. Freeze the stock solutions in aliquots until use. The solutions must not be heated above 30 °C to avoid the formation of acrylic acid. Addition of a small amount of mixed-bed ion exchanger catches traces of acrylic acid and depresses interactions between gel matrix and protein. 

A soln of HCl-H-(Bzl)Gly-(Bzl)Gly-(Bzl)Gly-OTcp (2.15 g, 3 mmol) in pyridine (1.5 L) was stirred at 90 °C for 3 h. After removal of the solvent, the residue was treated with toluene several times to remove traces of pyridine. The residue was dissolved in MeOH and H20 and stirred overnight with mixed-bed ion-exchange resin (5g). The resin and the precipitate primarily c[-(Bzl)Gly-(Bzl)Gly-]j were filtered off the filtrate was taken to dryness and column chromatographed (Sephadex, DMF). The peptide containing eluate was concentrated to an oil that crystallized on addition of Et,0 it was recrystallized (MeOH) yield 0.3 g (19.5%). 

Mixed-bed ion-exchange resin amberlite MB3 (100 g Merck) is pretreated with 500 ml 10% acetic acid for 4 h, washed with distilled water and dried over 3 days. 

Formamide deionized by stirring for 30 mm with 10% (w/v) of a mixed-bed ion exchange resm (e.g, Bio-Rad AG 501-X8,20-50 mesh, Bio-Rad, Hercules, CA), filtering twice through Whatman (Clifton, NJ) no 1 paper and storing smgle-use aliquots at -80°C... 

Deionized formamide- Mix 5.0 g mixed-bed ion-exchange resin (Bio-Rad [Hercules, CA] AG501-x8,20-50 mesh) with 50 mL formamide. Stir for 45 mm, and filter with Whatman s filter paper. Store in aliquots at-20°C... 

Resistivity units are used almost exclusively to describe ultrapure water in the 10 megohm-cm to 18 megohm-cm (0.1 microsiemens/cm to 0.055 microsiemens/cm) range generated by mixed bed ion exchange and used as boiler feed water and in certain critical washing applications. 

Alternatively, excess hydrosulfite may be removed from the myoglobin solution via dialysis against the buffer of choice (1 vol protein 10 vol buffer, 3 times, 8 hr each) or via mixed-bed ion-exchange chromatography (e.g., AG501-X8, Bio-Rad) (Brown and Mebine, 1969). 

United States Patents. Gilliland s patent (7) covers mixed-bed ion exchange of nonvolatile salts for thermolytic salts"—those which decompose on heating or reduction of pressure into gaseous compounds, or into gases and insoluble solids—followed by recovery of the thermolytic salt and its re-use for regeneration of the ion exchange bed. Ammonium bicarbonate is specifically claimed as one of the possible thermolytic salts. 

Quantitative Data. A series of 18 experimental runs was made to determine quantitatively the performance of a mixed-bed ion exchange column using Chemical Process Co. resins C-20 and A-102. Laboratory data are summarized in Table I. 

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