New lead-sensitive ion selective electrode with low detection limit

Department of Analytical Chemistry and Instrumental Analysis, Chemical Faculty, M. Curie-Sklodowska University, M. Curie-Sklodowaka Sq. 3, Lublin, Poland

^a cecylia.wardak@poczta.umcs.lublin.pl
^b j.lenik@poczta.umcs.lublin.pl

Abstract

A new polyvinylchloride membrane sensor for Pb²⁺ with solid contact has been prepared. The electrode membrane phase contains 1-heksyl-3-methylimidazolium hexafluorophosphate (HMImPF₆) as lipophilic ionic additive. The electrode shows a Nernstian response for lead ions over a wide concentration range (1×10⁻⁸−1×10⁻¹ mol L⁻¹) and the slope of 28.1 mV/decade. The limit of detection is 2.3×10⁻⁹ mol L⁻¹. It has a fast response time of 5-7 s and can be used more than 2 months without any divergence in potential. The proposed sensor is not pH sensitive in the range 4.0-6.9 and shows a very good discriminating ability towards Pb²⁺ ion in comparison with some alkali, alkaline earth, transition and heavy metal ions. It was successfully applied as an indicator electrode in potentiometric titration of lead ions with K₂CrO₄ and for direct determination of Pb²⁺ ions in real sample solution.