Used gold nano-particles as an on/off switch for response of a potentiometric sensor to Al(III) or Cu(II) metal ions

The potentiometric response of a carbon paste electrode modified with silica sol-gel and mercaptosuccinic acid (MSA) in the presence and absence of gold nano-particles was studied. The results showed that the electrode with gold nano-particles was responded to Al3+ ions as a hard metal ion. On the other hand, the electrode without gold nano-particles was responded to copper ions as a soft metal ion. The electrodes without and with gold nano-particles exhibits a Nernstian slope of 29.1 and 19.2 mV decade(-1) for copper and aluminum ions over a wide concentration range of 4.3 x 10(-7)-1.0 x 10(-2) and 4.5 x 10(-7)-1.6 x 10(-3) mol L-1, respectively. The detection limits of electrodes were 4.0 x 10(-7) and 1.6 x 10(-7) mol L-1 for copper and aluminum ions, respectively. (C) 2011 Elsevier B.V. All rights reserved.