Comparing the Chelating Abilities of EDTA, N-acetylcysteine (NAC) and N-acetylcysteine Amide (NACA) to Pb(II) by X-Ray Photoelectron (XPS) and UV-vis Spectroscopies
Prior in vivo studies on the treatment of lead poisoning using EDTA, penicillinamine (Pen), selenocysteine (Sel), Succimer, N-acetylcysteine (NAC) and N-acetylcysteine amide (NACA) as chelators showed differences in their ability to decrease both Pb(II) levels and oxidative stress. This present study, performed in vitro, was undertaken to further delineate the chelating abilities of these antioxidants. UV-vis spectroscopy was used to measure binding constants of the antioxidant-Pb complexes. X-ray photoelectron spectroscopy (XPS) was adopted as a rapid and direct method to quantify the degree of binding of these antioxidants to Pb(II). Pb-antioxidant complexations were performed at 0–10⁰C, dissolving antioxidant and Pb acetate in the distilled water. NACA was found to have the highest degree of chelation of the antioxidants in the series as demonstrated by its high binding constant from the UV data. Deconvolution of the Pb 4f orbitals showed greater amounts of Pb(II) precipitates accompanying Pb-NACA complexation as compared to the formation of Pb-NAC and Pb-EDTA, providing corroborating data showing NACA to have the highest affinity for the metal.
E. Chen et al., "Comparing the Chelating Abilities of EDTA, N-acetylcysteine (NAC) and N-acetylcysteine Amide (NACA) to Pb(II) by X-Ray Photoelectron (XPS) and UV-vis Spectroscopies," Abstracts of Papers of the American Chemical Society, American Chemical Society (ACS), Aug 2009.
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