Ion exchange columns, preparation

Ion exchange column. Prepare the Chelex-100 resin (100- 500 mesh) by digesting it with excess (about 2-3 bed-volumes) of 2M nitric acid at room temperature. Repeat this process twice and then transfer sufficient resin to fill a 1.0 cm diameter column to a depth of 8 cm. Wash the resin column with several bed-volumes of de-ionised water. 

Ion exchange column. Prepare a glass column of dimensions about 1 X 30 cm. Slurry pack with Bio-Rad AG1-X2 anion exchange resin, 50-100 mesh, hydroxide form and Bio-Rad AG 50W-X8 cation exchange resin, 50-100 mesh, acid form, each to about 10 cm depth. One column may be used about six times, depending on sample impurities. 

Fig. 5. Fermentative production of amino acids (140). A, pure culture B, inoculation C, boiler D, air compressor E, air filter F, seed tank G, ammonia water for pH control H, fermenter I, sterilizer , culture media K, preparation tank L, centrifugal separator M, ion-exchange column N, crystallizing...

Tetramethylammonium hydroxide (5H2O) [10424-65-4 (5H2O), 75-59-2 (aq soln) ] M 181.2, m 63°, 65-68°. Freed from chloride ions by passage through an ion-exchange column (Amberlite IRA-400, prepared in its OH" form by passing 2M NaOH until the effluent was free from chloride ions, then washed with distilled H2O until neutral). A modification, to obtain carbonate-free hydroxide, uses the method of Davies and Nancollas [Nature 165 237 1950]. 

A very simple and elegant alternative to the use of ion-exchange columns or extraction to separate the mixture of D-amino add amide and the L-amino add has been elaborated. Addition of one equivalent of benzaldehyde (with respect to die D-amino add amide) to the enzymic hydrolysate results in the formation of a Schiff base with die D-amino add amide, which is insoluble in water and, therefore, can be easily separated. Add hydrolysis (H2SQ4, HX, HNO3, etc.) results in the formation of die D-amino add (without racemizadon). Alternatively the D-amino add amide can be hydrolysed by cell-preparations of Rhodococcus erythropolis. This biocatalyst lacks stereoselectivity. This option is very useful for amino adds which are highly soluble in die neutralised reaction mixture obtained after acid hydrolysis of the amide. 

Sulfoxides without amino or carboxyl groups have also been resolved. Compound 3 was separated into enantiomers via salt formation between the phosphonic acid group and quinine . Separation of these diastereomeric salts was achieved by fractional crystallization from acetone. Upon passage through an acidic ion exchange column, each salt was converted to the free acid 3. Finally, the tetra-ammonium salt of each enantiomer of 3 was methylated with methyl iodide to give sulfoxide 4. The levorotatory enantiomer was shown to be completely optically pure by the use of chiral shift reagents and by comparison with a sample prepared by stereospecific synthesis (see Section II.B.l). The dextrorotatory enantiomer was found to be 70% optically pure. 

Streptokinase is a 48 kDa extracellular bacterial protein produced by several strains of Streptococcus haemolyticus group C. Its ability to induce lysis of blood clots was first demonstrated in 1933. Early therapeutic preparations administered to patients often caused immunological and other complications, usually prompted by impurities present in these products. Chromatographic purification (particularly using gel filtration and ion-exchange columns) overcame many of these initial difficulties. Modern chromatographically pure streptokinase preparations are usually supplied in freeze-dried form. These preparations (still obtained by non-recombinant means) often contain albumin as an excipient. The albumin prevents flocculation of the active ingredient upon its reconstitution. 

A combined technique has been developed for the preparative isolation of anthocyanins from blackcurrant (Ribes nigrum) fruits. Frozen berries (370 g) were extracted three times with 11 of methanol containing 0.1 per cent TFA at 4°C for 6 h. The combined exracts were concentrated, diluted to 250 ml with water and extracted with ethyl acetate. The aqueous phase was concentrated to 100 ml and applied in an ion-exchange column. The column... 

The preparation of a 1 1 Cr -PuO complex has been achieved by the oxida-dation of Pu by Cr207, the resulting green complex being purified on an ion-exchange column. ... 

The isolation of an individual glycosyl ester of a nucleoside pyrophosphate is a rather difficult task. Ion-exchange column-chromatography and preparative, paper-chromatography have been the main methods used for solving problems in separation. 

The new chemistry is based on a Sr-90/Y-90 separation using a-hydroxyisobutyric acid (a-HIB) and cation exchange chromatography (5). Once the activities are loaded onto the column, the steps to prepare the column for the a-HIB elution remove several of the possibile contaminants including rubidium and cobalt. Finally, the a-HIB elution also removes a wide range of other elements as well, leaving strontium on the ion exchange column (6). 

A reversed-phase liquid chromatographic method was developed for simultaneous determination of carboxylic acids, phenolic compounds, and SA in white wines (84). The diluted samples are injected into a Spherisorb ODS-2 column with a gradient of sulphuric acid (pH 2.5)/methanol as mobile phase. A diode array detector is used, set at 210 nm for carboxylic acids and altered to 278 nm, during the run, for phenolics and SA. The identification of compounds is based on retention time and UV spectra. Some cleanup methods (Sep-Pak C18 and an ion-exchange column) were tested and did not improve the results. The analysis was considered simple, with no sample preparation. Application of this method was illustrated by analyses of Brazilian Welchriesling wines (84). 

In the course of this work two phenomena were noted for which no explanation was sought. When ammonium bicarbonate was added to sea water to prepare a regenerant solution, a white precipitate was formed which was settled out and discarded with no attempt made at chemical analysis. Toward the end of some of the regeneration cycles and at the start of some of the feed cycles, gas was evolved in the ion exchange columns, which eventually disappeared. This gas, which was not identified, caused serious flow impedance. 

---