Sulfate homogeneous precipitant

Wagner, W.F. and Wuellner, J.A. (1952) Homogeneous precipitation of barium sulfate by hydrolysis of sulfamic acid. Anal. Chem., 24, 1031-1032. 

Pillai and Ganguly [286] have concentrated the nucleic acids from seawater by adsorption on homogeneously precipitated barium sulfate, then hydrolysed with 0.02 M hydrochloric acid and analysed for the constituents. 

Becker-Doiing nucleation hypothesis indicates a much larger number, of the order of 100, for the critical cluster. Klein and Driy, in nucleation studies combining the drop method and homogeneous precipitation, found the rate of nucleation of strontium sulfate to depend on the 27th power of the concentration, indicating a nucleus containing 52 ions. 

Nucleation Fischer found that, in PFHS, nucleation takes place early and only growth occurs thereafter. In the homogeneous precipitation of barium sulfate by sulfate generation from sulfamic acid in a solution containing 0.01 Af barium ion, he found (Section 8-2) that the number of particles was sensibly constant from the beginning to the end of precipitation. Evidently nucleation was complete within the first small fraction of the total precipitation time. From the rate of sulfate generation it... 

Anion or cation generation Anions can be generated slowly in solution to bring about homogeneous precipitation. Swift and Butler reviewed precipitation of the metal sulfides by use of thioacetamide or thiourea. PFHS of sulfides of cadmium, mercury, zinc, and nickel have been studied more recently by Swift and others. Phosphate can be generated by hydrolysis of triethyl phosphate, oxalate by hydrolysis of methyl oxalate, and sulfate by hydrolysis of diethyl sulfate or sulfamic acid. 

Ga203-based dodecyl sulfate mesophase[184] with a hexagonal structure was synthesized by the homogeneous precipitation method using urea. On removal of the incorporated surfactants by chemical or thermal treatment the mesophase structure collapsed. 

Physicochemical studies have also been performed on carboxymethyl-ated 0-methyl- and 0-(2-hydroxyethyl)-cellulose. As with other car-boxymethylated polysaccharides, the degree of substitution and the distribution of substituents play a dominant role in the viscosity of aqueous solutions of O-(carboxymethyl)starch. Viscosimetric "" and other measurements indicate that 0-(carboxymethyl)amylose exists as a random coil in solution, " and that the chains are stiffer than the corresponding cel-lulosic chains whereas the stiffness of the chains of 0-(carboxy-methyl)dextran is little different from that of other charged ether derivatives of dextran and dextran sulfate. Fractional precipitation is a useful procedure for obtaining homogeneous fractions of carboxymethylated polysaccharides, as with other polysaccharide ethers. Acetylated O-(carboxymethyl) cellulose provides a useful basis for the formation of desalination membranes. ... 

Glucose-U- C and Na2 S, both at 10 M, were incubated with homogenized frozen squid optic ganglia in 10" M HEPES (N-2-hydroxy-ethylpiperazine-N -2-ethanesulfonate) buffer, pH 7.5, for 5 hrs at 30°. Thereafter protein was precipitated, and from the soluble part, unused glucose and sulfide were separated from the sulfate-plus-isethionate peak on an Aminex A-4 (BioRad) column, sulfate and carrier sulfate were precipitated as BaS04, and hexose phosphates were hydrolyzed by heating in 1 M NaOH. These procedures were intersper-... 

Potassium sulfate has a solubility of 15 g/100 g water at 40°C. A solution is prepared by adding 39.0 g of potassium sulfate to 225 g of water, carefully heating the solution, and cooling it to 40°C. A homogeneous solution is obtained. Is this solution saturated, unsaturated, or supersaturated The beaker is shaken, and precipitation occurs. How many grams of potassium sulfate would you expect to crystallize out ... 

Figure 11.9 Production of rhGH in . coli (as an intracellular protein). Subsequent to fermentation, the cells are collected by centrifugation or filtration. After homogenization, nucleic acids and some membrane constituents are precipitated by the addition of polyethyleneimine. Ammonium sulfate precipitation of the supernatant concentrates the crude rhGH preparation. Chromatographic purification follows, as illustrated...

Delincee and Radola100 used a commercial preparation, as well as fresh tomatoes, for the preparation, purification, and characterization of tomato pectinesterase. The tomatoes were pressed and then homogenized directly with ammonium sulfate at 70% saturation. The precipitate obtained was extracted with 0.3 M phosphate and repeatedly salted out with ammonium sulfate, and the product was separated on a column of Sephadex G-75. The pattern of separation was similar to that in preceding work.50,97 A detailed study of the size properties of pectinesterase was conducted by gel-filtration and sedimentation analysis.100 By column and thin-layer gel-filtration on Sephadex G-75, the approximate molecular weight of a number of preparations of tomato pectinesterase was determined, values of 24,000 and 27,000 being obtained. A possible interaction of the... 

The initial polymerizations were conducted with both homogeneous and emulsion conditions. In the homogeneous reactions, a mixture of metha-nolrdichloroethane was used to dissolve the sulfated monomer, and the initiator was introduced as a solution in dichloroethane. These reactions did not proceed to completion, even upon heating. During the reaction, the formation of a precipitate was observed, which could be attributed to the growing polymer chain. Although the monomer is soluble in methanol as a triethylammonium salt, the... 

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