Simultaneous detection of trace Pb(II), Cd(II) and Hg(II) by anodic stripping analyses with glassy carbon electrode modified by solid phase synthesized iron-aluminate nano particles

This paper presents an ultrasensitive simultaneous detection procedure for heavy metals (HMs) namely lead; Pb (II), cadmium; Cd(II) and mercury; Hg(II). A bimetallic iron-aluminate (Fe-Al) mixed metal-oxide nano-composite (MMON) on glassy carbon electrode was synthesized using novel solid phase synthesis method. An ammonium ion exchange reaction in solid reagent with simultaneous ammonia evolution produced unique rodshaped Fe-Al MMON without any solvent addition. The chitosan-mediated electrode (Ch-MMON/GCE) was used to simultaneously detect three most harmful HMs using three anodic stripping techniques namely, cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV). Three distinct stripping peaks were obtained with concentrations in parts per trillion (ppt) using each of these methods using acetate buffer (0.1 M, pH = 4.5). Obtained LODs for Cd(II), Pb(II), and Hg(II), being 1.678 ppt, 0.301 ppt and 0.658 ppt, respectively by CV whereas LSV gave 1.791 ppt, 0.798 ppt and 2.205 ppt respectively DPV yielded 0.068 ppt, 0.034 ppt and 0.053 ppt, respectively. As observed, DPV was found to be the most sensitive method even though all LOD values were well below the drinking water permissible limits stipulated by WHO. Possible mechanism of ultrasensitive HM detection by the Ch-MMON/GCE was discussed. The modified electrode was successfully used to measure HMs present in water of river Ganges water eliciting significant performance and reliability.