Cation-exchange resin columns calcium-form

To the neutralized filtrate, add sufficient oxalic acid to precipitate calcium and filter. Reneutralize the filtrate with ammonium hydroxide. Charge the filtrate onto a cationic exchange adsorption column containing 1,500 to 2,000 g of IRC-50 Amberlite in its ammonium form. Discard the eluate, wash the resin with water, and elute with 2N ammonium hydroxide. Collect 400 ml fractions and monitor by disc testing with S. aureus ATCC-6538P. Combine active fractions and evaporate to dryness under vacuum obtaining about 28 g of crude Antibiotic 6640 having an activity of about 500 mcm/g. 

Stationary Phase Use prepacked macroreticular polystyrene sulfonate divinylbenzene cation-exchange resin (2% to 8% cross-linked, 8- to 25-ptm particle size), preferably in the calcium or silver form. Examples of acceptable resins are Bio-Rad Aminex HPX-87C, or equivalent, for separating DPi-DP4 saccharides, and Aminex HPX-42C and HPX-42A, or equivalent, for separating DP1-DP7 saccharides. Maintain the column at 85° during operation. 

Chromatographic System Use a liquid chromatograph equipped with a refractive index detector that is maintained at a constant temperature and a 9-mm x 30-cm column packed with a strong cation-exchange resin, about 9 pm in diameter, consisting of sulfonated cross-linked styrene-divinylbenzene copolymer in the calcium form (Aminex HPX-87c, or equivalent). Maintain the column temperature at 85° + 0.5°, and the flow rate of the Mobile Phase at about 0.5 mL/min. Chromatograph the Standard Preparation, and record the peak responses as directed under Procedure. Replicate injections show a relative standard deviation not greater than 2.0%. 

Sugars and polyols had been separated on columns of cation-exchange resins in their calcium or barium form before it was realized that this separation is based on complex-formation. The method was discovered fortui-... 

The anomers of twelve aldoses have been separated on cation exchange resins in the sodium form (at 25°C) or the calcium form (at °C), and in some cases a peak corresponding to the furanose forms has also been observed. Post-column derlvatlzatlon with 2-cyanoacetamlde was used to render the method sufficiently... 

Cation-exchange resins in the calcium or bariiun form have also been employed. A column of styrene-divinylbenzene resin, 8% cross-linked (220-400 mesh, Ba form) can separate mannitol, sorbitol, and xylitol. Borate buffers are used as eluents from 5 to 40 mmol 1 Sugar alcohols can also be separated in Dowex 450W x 2 (200-400 mesh, Ca form) columns by using only water as an eluent. 

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