Optical sensing of heavy metal ions in anionic micellar solution using a Pd porphyrin phosphorescent probe

Using sodium sulfite as an oxygen scavenger, meso-tetra (4-N,N,N- trimethylanilinium) porphyrin-Pd (Pd-TAPP) emts strong and stable room temperature phosphorescence (RTP) in sodium dodecyl sulfate (SDS) micellar Solution. Heavy metal ions, including Fe2+, Co2+, Ni2+ and Cu2+ can efficiently quench the phosphorescence of Pd-TAPP, The Stern-Volmer constants increased in the order Fe2+ < Co2+ < Cu2+ < Ni2+. directly reflecting the relative sensitivity of the method for these ions. The detection limits calculated following the 3 sigma IUPAC criteria are: 2.3 x 10(-7) mol/L for Cu2+, 3.4 x 10(-7) mol/L for Co2+, 1.2 x 10(-7) mol/L for Ni2+ and 2.1 x 10(-6) mol/L for Fe2+. The addition of these ions also resulted in reduction of the lifetime (tau) of Pd-TAPR The linear relationship between the concentration of Fe2+, Co2+, Ni2+ or Cu2+ ions and tau(0)/tau indicated the dynamic quenching mechanism. (C) 2009 Elsevier B.V. All rights reserved.