PVC-based membranes of N,N′-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane as Pb(II)-selective sensor

A new poly(vinyl chloride) membrane sensor for Pb(II) ions based on N,N′-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (I) as an ionophore was prepared. The sensor exhibits a Nernstian response for lead ions over a wide concentration range of 8.2 × 10−6 to 1.0 × 10−1 M with a slope of 30.0 ± 0.1 mV/decade of activity. It has a fast response time of about 10 s and can be used for at least 3 months without any divergence in potential. The electrode can be used in the pH range 2.0–6.8. The proposed sensor shows fairly good discriminating ability towards lead ions in comparison with some alkali, alkaline earth, transition and heavy metal ions. It was successfully applied for the direct determination of Pb(II) ions in solution and as an indicator electrode in potentiometric titration of lead ions with EDTA.