Mercury(II) ion-selective polymeric membrane sensor based on a recently synthesized Schiff base

A new polyvinyl chloride (PVC) membrane electrode that is highly selective to Hg(II) ions was prepared by using bis[5-((4-nitrophenyl)azo salicylaldehyde)] (BNAS) as a suitable neutral carrier. The sensor exhibits a Nernstian response for mercury ions,over a wide concentration range (5.0 x 10(-2) -7.0 x 10(-7) M) with a slope of 30+/-1 mV per decade. It has a response time of < 10 s and can be used for at least 3 months without any measurable divergence in potential. The electrode can be used in the pH range from 1.0 to 3.5. The proposed sensor shows fairly good discriminating ability towards Hg2+ ion in comparison with some hard and soft metals. The electrode was used in the direct determination of Hg2+ in aqueous solution and as an indicator electrode in potentiometric titration of mercury ions. (C) 2003 Elsevier Science B.V. All rights reserved.