Silica glass modified with flavonoid derivatives for preconcentration of some toxic metal ions in water samples and their determination with ICP-MS.

Quercetin (3,3',4',5,7-pentahydroxyflavone) chemically bonded through pyran rearrangement on modified controlled pore silica glass (QCPSG) with a capacity 0.213 mmol/g was used for solid phase extraction of some toxic metal and metalloid ions. The newly designed QCPSG quantitatively sorbs As(V), Cd(II), Hg(II), and Pb(II) at the pH range 7.5-8.5 after 10 min of stirring. HCl (1 mol L(-1)) instantaneously elutes all the metal ions. The sorption capacity of the ion collector is 0.42, 0.46, 0.53, and 0.49 mmol g(-1) for As(V), Cd(II), Hg(II), and Pb(II), respectively, whereas the preconcentration factor is 200. The effect of NaCl, Na2SO4, NaF, NaBr, Na3PO4, and other interfering salts on the sorption of metal ions (50 microg L(-1)) was reported. Analytical detection limits of As(V), Cd(II), Hg(II), and Pb(II) were 4.18, 2.44, 15.86, and 25.00 pg mL(-1), respectively. QCPSG was used in the separation of the investigated metal ions from some natural water samples collected from diverse origins followed by determination by inductively coupled plasma-mass spectrometry. The data were compared with those obtained by the standard methods of determination using atomic absorption (hydride generation, HGAAS and after solvent extraction with ammonium pyrolidine dithiocarbamate/methyl isobutyl ketone). The suggested solid phase extraction method was found accurate with no random error.