Procedures water exchange

The batch and fed-batch procedures are used for most commercial antibiotic fermentations. A typical batch fermentor may hold over 150,000 Hters. When a maximum yield of antibiotic is obtained, the fermentation broth is processed by purification procedures tailored for the specific antibiotic being produced. Nonpolar antibiotics are usually purified by solvent extraction procedures water-soluble compounds are commonly purified by ion-exchange methods. Chromatography procedures can readily provide high quaHty material, but for economic reasons chromatography steps are avoided if possible. 

Campbell, M., G. Bitton, B. Koopman, and J.J. Delfino. 1992. Preliminary comparison of sediment extraction procedures and exchange solvents for hydrophobic compounds based on inhibition of bioluminescence. Environ. Toxicol. Water Qual. 7 329-338. 

When water samples collected from the field were spiked with the 6-endotoxin and tested, sensitivity and precision of the ELISA procedure decreased regardless of the pH tested. Two procedures, anion exchange chromatography and dot-blotting, were explored for sample clean-up and concentration when sample work-up is needed. In addition, problems with assay development are also discussed. As more biochemical agents are introduced into the agricultural market, derived either from classical or molecular approaches, it is critical that analytical methods are in place for quality control and to monitor the presence of these agents in the environment. 

Using only the standard procedure, water-soluble fractions of the original sample are obtained in the elutriate hydrophobic and even some soluble substances, which are adsorbed or immobilised to the organic or inorganic matrix by ion exchange bonds, will be retained in the solid residue. If substances with a moderate solubility... 

For the calibration curve run known amounts of methylmercury dicyandiamidethrough the whole procedure, only exchanging the fish for the same amount of water. 

The [Pd(NH3)4] /NaY was prepared by above procedure (ion exchange method) and Pd/Cald was obtained commercially. After the reaction the [Pd(NH3)4]/NaY and Pd/CALO catalysts were recovered following the above procedure using only DMF instead of mixture of DMF and water for three times and dried for overnight. Both catalysts have shown high recyclability up to fiftii cycle without any significant loss of catalytic activity. However, the reaction between o-iodo phenol and diphenyl acetylene failed to provide benzofuran derivative in the presence of above two catalysts. 

The purified commercial di-n-butyl d-tartrate, m.p. 22°, may be used. It may be prepared by using the procedure described under i o-propyl lactate (Section 111,102). Place a mixture of 75 g. of d-tartaric acid, 10 g. of Zeo-Karb 225/H, 110 g. (136 ml.) of redistilled n-butyl alcohol and 150 ml. of sodium-dried benzene in a 1-litre three-necked flask equipped with a mercury-sealed stirrer, a double surface condenser and an automatic water separator (see Fig. Ill, 126,1). Reflux the mixture with stirring for 10 hours about 21 ml. of water collect in the water separator. FUter off the ion-exchange resin at the pump and wash it with two 30-40 ml. portions of hot benzene. Wash the combined filtrate and washings with two 75 ml. portions of saturated sodium bicarbonate solution, followed by lOu ml. of water, and dry over anhydrous magnesium sulphate. Remove the benzene by distillation under reduced pressure (water pump) and finally distil the residue. Collect the di-n-butyl d-tartrate at 150°/1 5 mm. The yield is 90 g. 

It would not be expected that crevice corrosion could easily occur in demineralized water. However, this exchanger was subject to extended outages with no lay-up procedures. Under such conditions, crevice attack is more likely. 

Another serious problem in heat exchangers is corrosion. Severe corrosion can and does occur in tubing and very often with common fluids such as water. Proper material selection based on a full analysis of the operating fluids, velocities and temperatures is mandatory. Very often, heavier gauge tubing is specified to offset the effects of corrosion, but this is only a partial solution. This should be followed by proper start-up, operating and shut-down procedures. 

A solution of estradiol (38, 15 mg) in methanol-OD (4 ml) and one drop of 10% deuteriosulfuric acid in deuterium oxide is heated under reflux for 5 days. After cooling the reaction mixture is diluted with ether, washed with dilute sodium bicarbonate solution and water, then dried over anhydrous sodium sulfate. Evaporation of the ether gives crystalline 2,4-d2-estradiol (39, 15 mg, 99%), mp 173-175° (ether-hexane), exhibiting 82% isotopic purity and only one aromatic hydrogen by NMR. (For an experimental procedure describing the exchange of aromatic protons under Clemmensen conditions, see section III-D.)... 

After completion of the reaction, the mixture is diluted with water, extracted with ether and the residue from the ether phase purified by chromatography and/or recrystallization. If the substrate contains aromatic protons, the reduction procedure is repeated in protic medium to back exchange deuteriums incorporated into the aromatic ring. 

---