Additives sulfate salts

Coa.cerva.tlon, A phenomenon associated with coUoids wherein dispersed particles separate from solution to form a second Hquid phase is termed coacervation. Gelatin solutions form coacervates with the addition of salt such as sodium sulfate [7757-82-6] especially at pH below the isoionic point. In addition, gelatin solutions coacervate with solutions of oppositely charged polymers or macromolecules such as acacia. This property is useful for microencapsulation and photographic apphcations (56—61). 

After sulfuric acid work-up (accompanied by the formation of sodium sulfate), the resorcinol is extracted and isolated in a 94% yield based on y -benzenedisulfonic acid [98-48-6]. In addition to the technical complexity that goes along with the manipulation of soHds at high temperature, this process produces large amounts of salts (sulfite and sulfate salts) which economically as well as environmentally are not always desired. 

Purification. Enzyme purity, expressed in terms of the percent active enzyme protein of total protein, is primarily achieved by the strain selection and fermentation method. In some cases, however, removal of nonactive protein by purification is necessary. The key purification method is selective precipitation of the product or impurities by addition of salt, eg, sodium sulfate, or solvent, eg, ethanol or acetone by heat denaturation or by isoelectric precipitation, ie, pH adjustments. Methods have been introduced to produce crystalline enzyme preparations (24). 

The precious-metal platinum catalysts were primarily developed in the 1960s for operation at temperatures between about 200 and 300°C (1,38,44). However, because of sensitivity to poisons, these catalysts are unsuitable for many combustion apphcations. Variations in sulfur levels of as Httle as 0.4 ppm can shift the catalyst required temperature window completely out of a system s operating temperature range (44). Additionally, operation withHquid fuels is further compHcated by the potential for deposition of ammonium sulfate salts within the pores of the catalyst (44). These low temperature catalysts exhibit NO conversion that rises with increasing temperature, then rapidly drops off, as oxidation of ammonia to nitrogen oxides begins to dominate the reaction (see Fig. 7). 

Sulfate ions have reactions similar to those of chloride. They are corrosion-causative agents (similar to oxygen and hydrogen) of the various types of concentration cell corrosion. In addition, they also are depassivation agents and may greatly accelerate the risk of stress corrosion mechanisms. Saline corrosion pits resulting from high concentrations of chloride and sulfate salts also may be associated with low pH corrosion because hydrochloric acid and sulfuric acid can form within the pit, under deposits. 

Acid addition is commonly used to convert bicarbonates into the more soluble sulfate salts to reduce the alkalinity of the RO RW, which in turn modifies the brine reject water LSI. Sometimes it is required to maintain the pH level within membrane limits. Additionally, it may be used in conjunction with a reduced dosage of antiscalent chemical to reduce the overall chemical treatment costs. 

The precipitation method of separation involves the addition of salts such as ammonium sulfate or solvents such as polyethylene glycol to the reagent mixture to cause precipitation of the large molecular weight bound species. These methods of precipitation lack specificity and work well only when there is a large difference between the molecular weight of the material being measured and that of the bound complex of it. 

Suppose we add a solution of Na2S04 to this equilibrium system. The additional sulfate ion will disrupt the equilibrium by Le Chatclier s principle and shift it to the left. This decreases the solubility. The same would be true if you tried to dissolve PbS04 in a solution of Na2S04 instead of pure water—the solubility would be less. This application of Le Chatelier s principle to equilibrium systems of a slightly soluble salt is the common-ion effect. 

Alkaline hydrolysis with barium, sodium, or lithium hydroxides (0.2-4 M) at 110°C for 18-70 h126-291 requires special reaction vessels and handling. Reaction mixtures are neutralized after hydrolysis and barium ions have to be removed by precipitation as their carbonate or sulfate salts prior to analysis which leads to loss of hydrolysate. Correspondingly, peptide contents are difficult to perform by this procedure. Preferred conditions for alkaline hydrolysis are 4M LiOH at 145 °C for 4-8 h where >95% of tryptophan is recovered 291 An additional inconvenience of the alkaline hydrolysis procedure is the dilution effect in the neutralization step and thus the difficult application to the analyzer if micro-scale analysis is to be performed. The main advantage is the good recovery of tryptophan and of acid-labile amino acid derivatives such as tyrosine-0-sulfate1261 (Section 6.6) as well as partial recovery of phosphoamino acids, particularly of threonine- and tyrosine-O-phosphate (Section 6.5). 

For the Kaufmann method,3 even larger amounts of sulfate salt had to be removed before the [BCS] " salt was isolated. This was accomplished by the addition of excess ammonia and coprecipitation of ammonium sulfate and ammonium a-bromocamphor-7t-sulfonate, followed by extraction of the latter compound with ethanol. This method is clearly superior to previous methods, but from our experience the yields are variable, presumably because optimal sulfonation yields are critically dependent on reaction conditions, which consequently need to be carefully controlled. The following method combines... 

Colistin is a linear-ring peptide antibiotic. Its main components are colistin A and colistin B. It is a member of the polymyxin family of antibiotics that is stable in dry form and in water solution. The sulfate salt of colistin, which is usually administered as feed additive, is soluble in water, slightly soluble in methanol, and practically insoluble in acetone and ether. Colistin components do not have any specific fluorophore and UV chromophore, so detection by liquid chromatography at residue levels of interest is difficult without including a suitable derivatization step in the analytical method. 

Demineralization, like the zeolite process, involves ion exchange. The metal ions are replaced with hydrogen ions by means of the process and equipment described for the hydrogcn-zcolitc system (see Hot Lime Zeolite—Split Stream Softening, previously described). In addition, the salt anions (bicarbonate, carbonate, sulfate and chloride) are replaced by... 

Because formamidine hydrochloride is extremely deliquescent, considerable care must be exercised in its preparation if satisfactory results are to be achieved. Furthermore, formamidine hydrochloride cannot be used directly in most condensation reactions it must be treated first with a mole of base to liberate free formamidine. The same restriction applies to the metho-sulfate salt of formamidine in addition, complications in synthesis may be anticipated in this latter case because methyl hydrogen sulfate itself is an effective methylating agent.6... 

The addition of salt precipitates proteins because the protein solubility is reduced markedly by the increase of salt concentration in solution. Precipitation is effective and relatively inexpensive. It causes little denaturation. Ammonium sulphate is the most commonly employed salt. The disadvantage of ammonium sulphate is that it is difficult to remove from the precipitated protein. Sodium sulfate is an alternative but it has to be used at 35-40°C for adequate solubility. 

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