کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5372325 | 1503980 | 2007 | 9 صفحه PDF | دانلود رایگان |

The acid base behavior of phytate has been studied (at t = 25 °C by potentiometry, ISE-H+ glass electrode) in NaNO3aq at different ionic strengths (0.1 â¤Â I/mol Lâ 1 â¤Â 1.0). The interactions with copper(II) were investigated in the same experimental conditions in different metal to ligand (Phy) ratios (1:1 â¤Â Cu2+:Phy â¤Â 4:1), by using both ISE-H+ and ISE-Cu2+ electrodes. Phytate acid base behavior in sodium nitrate is very similar to that in sodium chloride, previously investigated. In the experimental conditions adopted, the formation of three CuiHjPhy(12â2iâj)â species is observed: the mononuclear CuH4Phy6â and CuH5Phy5â, and the dinuclear Cu2H5Phy3â. Analysis of complex formation constants at different ionic strengths reveals that both ISE-H+ and ISE-Cu2+ electrodes gave, within the experimental error, analogous values. Dependence of complex formation constants on ionic strength was modeled by EDH (Extended Debye-Hückel) and SIT (Specific ion Interaction Theory) equations. The sequestering ability of phytate toward copper(II) has been evaluated by the calculation of pL50 (the total ligand concentration, as â log CL, able to bind 50% of metal cation), an empirical parameter already proposed for an objective “quantification” of this ability. A thorough analysis of literature data on phytate-copper(II) complexes has been performed.
Journal: Biophysical Chemistry - Volume 128, Issues 2â3, July 2007, Pages 176-184