Electrochemical detection of Hg(II) in water using self-assembled single walled carbon nanotube-poly(m-amino benzene sulfonic acid) on gold electrode

This work reports on the detection of mercury using single walled carbon nanotube-poly (m-amino benzene sulfonic acid) (SWCNT-PABS) modified gold electrode by self-assembled monolayers (SAMs) technique. A thiol containing moiety (dimethyl amino ethane thiol (DMAET)) was used to facilitate the assembly of the SWCNT-PABS molecules onto the Au electrode surface. The successfully assembled monolayers were characterised using atomic force microscopy (AFM). Cyclic voltammetric and electrochemical impedance spectroscopic studies of the modified electrode (Au-DMAET-(SWCNT-PABS)) showed improved electron transfer over the bare Au electrode and the Au-DMAET in [Fe (CN)₆]^{3 −/4 −} solution. The Au-DMAET-(SWCNT-PABS) was used for the detection of Hg in water by square wave anodic stripping voltammetry (SWASV) analysis at the following optimized conditions: deposition potential of − 0.1 V, deposition time of 30 s, 0.1 M HCl electrolyte and pH 3. The sensor showed a good sensitivity and a limit of detection of 0.06 μM with a linear concentration range of 20 ppb to 250 ppb under the optimum conditions. The analytical applicability of the proposed method with the sensor electrode was tested with real water sample and the method was validated with inductively coupled plasma – optical emission spectroscopy.