Species size 13, Table soluble

Both dissolution and diffusion are important parameters in defining bioavailability of species by the i.m. or s.c. routes. Soluble neutral compounds disperse from intramuscular sites according to size Table 9.7 shows that mannitol, a small molecule, rapidly diffuses from the site of injection insulin... 

If it were possible to identify or quantitatively determine any element or compound by simple measurement no matter what its concentration or the complexity of the matrix, separation techniques would be of no value to the analytical chemist. Most procedures fall short of this ideal because of interference with the required measurement by other constituents of the sample. Many techniques for separating and concentrating the species of interest have thus been devised. Such techniques are aimed at exploiting differences in physico-chemical properties between the various components of a mixture. Volatility, solubility, charge, molecular size, shape and polarity are the most useful in this respect. A change of phase, as occurs during distillation, or the formation of a new phase, as in precipitation, can provide a simple means of isolating a desired component. Usually, however, more complex separation procedures are required for multi-component samples. Most depend on the selective transfer of materials between two immiscible phases. The most widely used techniques and the phase systems associated with them are summarized in Table 4.1. 

Selected nickel(II) complexes with TV-substituted diamines are also shown in Table 41. It is usually found that as the number and size of the substituents increase, the number of the coordinated diamines decreases, as does the stability of the complexes which are, in general, sensitive to moisture. The complexes are soluble in dry solvents without dissociation or decomposition. Pseudotetrahedral coordination is stabilized by increasing the steric hindrance on the donor atoms. In the series of tetrasubstituted diamines the pseudotetrahedral species are stabilized in the order Me4en < Me4pn < Me4tmd and NCS < Cl < Br < I (Table 41).646... 

To verify whether or not colloid species were present in solution, phase separation was thoroughly examined with different ultrafilters. Tables HI and IV show results from various ultrafiltrations for the Am(III) and Pu(VI) solutions, respectively. The solution at solubility equilibrium was first filtered with the Millex-22 (0.22 u) filter and further passed through different ultrafilters of nearly the same pore size ( 2nm). Table ID demonstrates that the americium concentration in filtrates... 

In water studies it is standard practice to filter the sample soon after collection, usually through a 0.45p,m membrane disc (made of cellulose acetate, cellulose nitrate or polycarbonate). This process arbitrarily divides the sample components into soluble and insoluble fractions, but as shown in Table 2.3, the average size of different chemical species varies widely, and some differentiation between species can be obtained through using filter media of different pore sizes. For example, fully dissolved compounds can be separated from finer colloidal forms by using gel filtration and dialysis, and sub-division of the total content into fractions based on particle or molecular size (see Section 2.3) has been used for speciation of elements in waters. 

Gas permeation through non-porous polymeric membranes is generally described by the solution-diffusion mechanism [2], This is based on the solubility of specific gases within the membrane and their diffusion through the dense membrane matrix. In turn, the solubility of a specific gas component within a membrane is a function of its critical temperature, as this is a measure of the gas condensability. Critical temperatures for a range of gas components are provided in Table 11.2. Conversely, the diffusivity depends upon the molecular size, as generally indicated by the kinetic diameter. Indeed, Robeson et al. [9] have recently postulated that the relationship between the ideal permeability of one species P, and that of another Pj are related by a simple function ... 

Table XV shows that the two methods used (equilibrium/ultracentrifugation and sedimentation/diffusion) give comparable results. The sodium taurocholate micelle is swollen appreciably by the presence of even small amounts of potassium oleate. As the weight ratio increases the micelle increases in size. It is not possible to say whether there are two different species of micelle present, although this seems unlikely since the schlieren sedimentation curve was symmetrical and showed no shoulders or second bumps that would suggest polydispersity. It is probable that sodium taurocholate and potassium oleate form a mixed micelle that increases in size as more oleate is added. Since both these compounds are soluble amphiphiles (42) they will be present in both the micelle and as monomers. At present it is impossible to know how the species are partitioned. If one assumes that the micelle composition is similar to that of the whole solution (a valid assumption at high micelle concentrations) then the number of molecules of each...

The platinum eleetroehemical dissolution rate in fuel cell operation is a critical durability issue due to loss of catalyst surface area vs. time. The dissolution behavior and solubility of platinum are governed by the chemical state of the platinum surfaee and the equilibrium platinum species in the solution. Temperature, pH, eleetrolyte composition, potential, and particle size are all major factors influencing the solubility and the dissolution rate. Potential cycling of Pt electrodes has been extensively investigated, and the platinum electrode dissolution rates from the literature are summarized in Table 23.5 [9, 33, 70-74], Both Pt(II) and Pt(IV) speeies were detected in sulfuric solution after potential cycling from... 

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