New lead-sensitive ion selective electrode with low detection limit

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.