Amino acid solution speciation

Figure 9 Plots showing the calculated mineral saturation indices as a function of pH for hydroxylapatite, quartz, and various asbestos-forming minerals in electrolyte solutions approximating the electrol)he compositions of lung fluids (approximated by interstitial fluids, upper plot) and intracellular fluids (lower plot). Electrolyte concentrations used as input were taken from Table 4. The CO2 partial pressure was fixed at the value for venous plasma for each speciation at a different pH. Organic species such as amino acids and other organic acids were not included in the calculations, but likely would have the effect of decreasing the calculated saturation indices somewhat due to their...

The large differences seen in Cu(II) adsorption capacity for thiol- and amino-modified silicas does not occur for Pb(II) adsorption (Figure 7). While it is tempting to argue these differences in adsorption behavior based on hard-soft acid-base theory the hardness of Cu2+ and Pb2+ are very similar, both generally categorized as intermediate cases.18 It is more likely that Pb(II) adsorption behavior under the conditions of this study is dictated largely by solution behavior and speciation of Pb2+ in aqueous solution at pH 5. Indeed it was found that these solutions were unstable and prone to precipitation slowly over time under these conditions. Further work will be needed as a function of pH, surface functionality, and metal ion to determine the role of various factors on adsorption behavior of these systems. 

VO(L ° )(OMe)(MeOH)] (2-MeOH) was studied by and NMR spectroscopies and DFT calculations, and the difference between the NMR chemical shifts of the two diastereomers for 1 or 2 is 30 or 28 ppm, respectively. The chemical speciation of 2-amino-N-hydro-(p-alaninohydroxamic acid, HL) and V(v) in aqueous solution was studied using the results obtained by the calculations of the thermodynamic properties and the NMR chemical shifts of the species formed at equilibrium and the experimental NMR measure-ments. The NMR chemical shifts were calculated by DFT approach accounting for relativistic corrections and solvent effects and all the tautomers of the 1 1 and 1 2 V02 /p-ala complexes with different... 

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