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 (5.0x10(-2)-7.0x10(-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 Hg(2+) ion in comparison with some hard and soft metals. The electrode was used in the direct determination of Hg(2+) in aqueous solution and as an indicator electrode in potentiometric titration of mercury ions.