Square wave voltammetric determination of Hg(II) using thiol functionalized chitosan-multiwalled carbon nanotubes nanocomposite film electrode

Covalent tethering of cysteamine to chitosan using glutaraldehyde yields thiol-functionalized chitosan (CS-SH). It was cast on a glassy carbon electrode which is found to be very stable in acidic solutions and to possess a strong affinity for Hg(II) ions as confirmed by quartz crystal microbalance measurements. A glassy carbon electrode modified with a nanocomposite made from CS-SH and multiwalled carbon nanotubes was applied for square wave voltammetric determination of Hg(II). The procedure comprises the steps of (a) chemical accumulation of Hg(II) under open-circuit condition and (b) electrochemical determination of Hg(II). Linear responses are obtained in the range from 10 to 140 nM, with a limit of detection of 3 nM (S/N = 3) under optimized conditions. The electrode was applied to the determination of Hg(II) in water samples with satisfactory recoveries.