Column method solubility

Hashimoto, Y., Tokura, K., Ozaki, K., Strachan, W.M.J. (1982) A comparison of water solubilities by the flask and micro-column methods. Chemosphere 11(10), 991-1001. 

The flow column method has useful advantages. Manipulation of the system prior to analysis is minimized, and so problems such as adsorption or evaporation that may arise from separation of the saturated solution and the undissolved solute are reduced. The method is rapid and precise [22,33,34], and it is valuable for sparingly soluble systems, such as hydrophobic solutes in water. 

Water solubility determined by the generator column method by van Haelst et al. [244]. n-Octanol/water partition coefficients determined by Van Haelst et al. using the slow stirring method [245]. 

Two general methods, the analytical method and the synthetic method (Grant and Brittain 1995), are available for determining solubility. In the analytical method, the temperature of equilibration is hxed, while the concentration of the solute in a saturated solution is determined at equilibrium by a suitable analytical procedure. The analytical method can be either the traditional, common batch agitation method, or the more recent flow column method. In the synthetic method, the composition of the solute-solvent system is hxed by appropriate addition and mixing of the solute and solvent, then the temperature at which the solid solute just dissolves or just crystallizes is carefully bracketed. 

The column method also has several steps which may result in a negative bias on measured aqueous solubility. The lack of water-solute equilibrium in the generator column itself may produce an outlet concentration lower than the "true solubility according to Stolzenburg and Andren (8). This result also has been modeled with a beta distribution (93-percent confidence level of -3 percent). 

Comparison of the column method KQW results with the results given by the column method for solubility in Figure 3 shows the shape of the distributions to be virtually identical with standard deviations being 4.0 percent for solubility and 4.2 percent for Kow. This corresponds to the similarities noted by DeVoe et al., (11). The column method, however, differs from the shake-flask by 9.2 percent in the case of Kow (versus 5 percent for solubility). Woodburn et al. (12) quote a difference of 10 percent between techniques. As indicated by comparing standard deviations, the column method seems as reproducible as the shake-flask method, but accurate calibration is even more necessary to prevent underprediction than was the case for column method for solubility. 

Figure 3. Distribution of simulated aqueous solubility from the column method (true value = 1.00).

The total binder recovery is carried out by using the rotary evaporator or the fractionating column method. Both methods are used mainly for the recovery of soluble binder from bituminous pavement materials in a form for further testing (penetration, softening point, viscosity, etc.). 

Hashimoto, Y., K. Tokura, K. Ozaki, and W.M.J. Strachan. A Comparison of Water Solubilities by the Flask and Micro-Column Methods, Chemosphere, 11(10) 991-1001 (1982). 

All of the tables contain a column relating solubility information. This column generally lists the solvents that have been reported for the polymer. If nothing was said about the solubility of the polymer in the original article, this column is left blank. If a polymer was described as being insoluble, this has been reported in the table. If data reported in the Molecular Weight column were obtained by solution methods, the first solvent listed under Solubility is the solvent that was used. 

Fluorozirconate Crystallization. Repeated dissolution and fractional crystallization of potassium hexafluorozirconate was the method first used to separate hafnium and zirconium (15), potassium fluorohafnate solubility being higher. This process is used in the Prinieprovsky Chemical Plant in Dnieprodzerzhinsk, Ukraine, to produce hafnium-free zirconium. Hafnium-enriched (about 6%) zirconium hydrous oxide is precipitated from the first-stage mother Hquors, and redissolved in acid to feed ion-exchange columns to obtain pure hafnium (10). 

Tailing peaks or longer than expected elution volumes are sometimes caused by low solubility of the protein in the mobile phase. Using a trial-and-error process, select the proper pFf and ionic strength to address this problem. Detergents such as sodium dodecyl sulfate (SDS) are sometimes helpful but, because they change the conformation of many proteins and are difficult to remove from the column should be used only if other methods fail. 

In the development of a SE-HPLC method the variables that may be manipulated and optimized are the column (matrix type, particle and pore size, and physical dimension), buffer system (type and ionic strength), pH, and solubility additives (e.g., organic solvents, detergents). Once a column and mobile phase system have been selected the system parameters of protein load (amount of material and volume) and flow rate should also be optimized. A beneficial approach to the development of a SE-HPLC method is to optimize the multiple variables by the use of statistical experimental design. Also, information about the physical and chemical properties such as pH or ionic strength, solubility, and especially conditions that promote aggregation can be applied to the development of a SE-HPLC assay. Typical problems encountered during the development of a SE-HPLC assay are protein insolubility and column stationary phase... 

In the case of photoinitiated polymerization, an oxygen-free aqueous solution of acrylamide with a concentration of about 50% mixed with a photosensibilizer and other required additives is passed through a column-type apparatus with exterior water-cooling. A thin layer of the solution is exposed to a mercury lamp, acquires the consistency of a plastic film, which then can be passed through a second exposure zone, and is crushed and dried. Acrylamide polymers produced by this method are easily soluble and have a low residual monomer content. 

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