Solubility measurement experimental materials

Sampling and Measurements. The determination of dissolved actinide concentration was started a week after the preparation of solutions and continued periodically for several months until the solubility equilibrium in each solution was attained. Some solutions, in which the solubilities of americium or plutonium were relatively high, were spectrophotometrically analyzed to ascertain the chemical state of dissolved species. For each sample, 0.2 to 1.0 mL of solution was filtered with a Millex-22 syringe filter (0.22 pm pore size) and the actinide concentration determined in a liquid scintillation counter. After filtration with a Millex-22, randomly chosen sample solutions were further filtered with various ultrafilters of different pore sizes in order to determine if different types of filtration would affect the measured concentration. The chemical stability of dissolved species was examined with respect to sorption on surfaces of experimental vials and of filters. The experiment was performed as follows the solution filtered by a Millex-22 was put into a polyethylene vial, stored one day, filtered with a new filter of the same pore size and put into another polyethylene vial. This procedure was repeated twice with two new polyethylene vials and the activities of filtrates were compared. The ultrafiltration was carried out by centrifugation with an appropriate filter holder. The results show that the dissolved species in solution after filtration with Millex-22 (0.22 ym) do not sorb on surfaces of experimental materials and that the actinide concentration is not appreciably changed with decreasing pore size of ultrafilters. The pore size of a filter is estimated from its given Dalton number on the basis of a hardsphere model used in the previous work (20). 

Although this discussion provides insight to the types of solubility behavior that can be exhibited by various systems, it is by no means a complete survey of the topic. Extensive solubility data and descriptions of more complex equilibrium behavior can be found in the literature. Published data usually consist of the influence of temperature on the solubility of a pure solute in a pure solvent seldom are effects of other solutes, co-solvents, or pH considered. As a consequence, solubility data on a system of interest should be measured experimentally, and the solutions used in the experiments should be as similar as possible to those expected in the process. Even if a crystallizer has been designed and the process is operational, obtaining solubility data using mother liquor drawn from the crystallizer or a product stream would be wise. Moreover, the solubility should be checked periodically to see if it has changed due to changes in the upstream operations or raw materials. 

Hydrothermal reactions typically produce nanometer-sized particles that can be quenched to form a nanoparticle powder or cross-linked to produce nanocrystalline stmctures (Feng and Xu, 2001). Hydrothermal conditions allow for reduction in solubilities of ionic materials and thus more rapid nucleation and increased ion mobility, resulting in faster growth. Via judicious choice of the hydrothermal conditions, a measure of control can be exerted over the size and morphology of the materials. As mentioned earlier, the viscosity and ionic strength of solvents is a function of the temperature and pressure at which the reaction is carried out. Other experimental parameters, such as the precursor material and the pH, have... 

Gas phase I2 also reacts with copper surfaces under formation of an iodide layer with measured iodine loadings of about l.Smg/cm. Since the calculated iodine amount of a monolayer of I2 is only on the order of 0.1 to 0.3mg/cm the measured amount either indicates a deposition in several layers or is due to the fact that the surface roughness of the experimental material was extremely high. When the system liquid water-metallic copper is investigated, it has to be taken into account that the Cul formed is poorly soluble in water (Deane and Marsh, 1990). 

Preparative photolysis of AETSAPPE (0.25 M aqueous solution) at 254 nm (Rayonet reactor) resulted in the formation of the disulfide product 2-amino(2-hydroxy-3-(phenyl ether) propyl) ether disulfide (AHPEPED) as the primary photoproduct Photolysis of AETSAPPE at 254 nm (isolated line of medium pressure mercury lamp) resulted in rapid initial loss of starting material accompanied by formation (analyzed by HPLC) of AHPEPED (Figure 12a and 12b) (Scheme IV). Similar results were obtained for photolysis- at 280 nm. Quantum yields for disappearance of AETSAPPE and formation of AHPEPED at 254 nm and 280 nm are given in Table I. The photolytic decomposition of AETSAPPE in water was also accomplished by sensitization ( x =366 nm) with (4-benzoylbenzyl) trimethylammonium chloride (BTC), a water soluble benzophenone type triplet sensitizer. The quantum yield for the sensitized disappearance (Table I) is comparable to the results for direct photolysis (unfortunately, due to experimental complications we did not measure the quantum yield for AHPEPED formation). These results indicate that direct photolysis of AETSAPPE probably proceeds from a triplet state. 

The experimental solubility of any given compound is quite straightforward to determine, given sufficient material. However, with a large number of samples, experimental determination of solubility becomes time consuming and tedious, and for databases encompassing millions of compounds, probably none of which are in hand, the measurement is impossible. While poor solubility does not necessarily rule the compound out as a marketable pharmaceutical, molecules with reasonable solubility are by far preferred over insoluble compounds for optimisation and development. 

Since most high molecular weight polymers do not mix on a molecular scale, it is desirable to determine compositional ranges of miscibility. The solubility of SAN copolymers with other polymers has been measured by a variety of techniques. The tendency of the materials to mix or phase separate is determined by the enthalpy of interactions between mer units in the polymers and by the molecular weight of the polymers. It was determined experimentally that... 

In this report, these concepts are applied to real proteins to collagen, an important structural material in tendons, bones, teeth, and skin, and to gelatin, the denatured product of collagen that is so important industrially. These materials are complex because of their 18 different, component amino acid side chains in addition, they present experimental difficulties because of their water solubility— they cannot be washed (e.g., with an aqueous detergent) to assure surface cleanliness. Furthermore, they are often of unknown purity. They do have the common polyamide backbone, and it is possible to transform the molecular configuration. The data are indicative of the potential utility of contact angle measurements of important, natural materials. No claim is made for adequate attention to the complex biochemistry of these materials. 

Pure liquids and solutions have probably received a major portion of the experimental effort devoted to the nonspectroscopic methods of detection. The liquid phase is susceptible to simple techniques and is the naturally occurring state for many substances. The principal methods of study are vapor pressure measurements, cryoscopy, solubility, and partition studies. To a lesser degree parachor, refractive index, thermal and acoustic conductivity, osmotic pressure, and magnetic susceptibility measurements have been applied to H bonded materials. Unfortunately, the difficulty of giving an adequate description of the liquid state sometimes produces problems of interpretation. 

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