Solid phase extraction of Pb(II), Cu(II), Cd(II) and Cr(III) with syringe technique using novel silica-supported bis(diazoimine) ligands

Novel multidentate silica-supported bis(diazoimine) ligands were synthesized and characterized by elemental analysis, solid phase NMR (Si-29 and C-13 CP MAS), FT-IR, TG/DTA, SEM and EDX techniques. In the synthesis, diazotized electrophiles of 1,4-diaminobenzene and 1,3-diaminobenzene coupled with 2,4-dihydroxybenzaldehyde to give bis(diazocarbonyl) compounds; (A(1): 5,5'-(1,4-phenylenebis(diazene-2,1-diyl))bis(2,4-dihydroxybenzaldehyde and A(2): 5,5'-1,3-phenylenebis(diazene-2,1-dil))bis(2,4-dihydroxybenzaldehyde)) which were chemically supported with amino-modified silica-gel (L1 and L2). The electrochemical properties of bis(diazocarbonyl) compounds (A1 and A2) were investigated by cyclic voltammetry. Optimum solid phase extraction parameters of the synthesized sorbents for syringe and batch techniques were determined by using ICP-OES. At optimum conditions, the recoveries of Pb(II), Cu(II), Cd(II) and Cr(III) were 95-99% +/- 2-3%. All the multifunctional multidentate silica-supported ligands showed highly effective solid phase extraction properties. (C) 2013 Elsevier B.V. All rights reserved.