Lead-selective membrane electrode based on dibenzyl phosphate Original Research Article

We found that dibenzyl phosphate can be used as an ionophore to make a lead-selective membrane electrode. An electrode constructed using dibenzyl phosphate and bis(1-butylpentyl) adipate as a solvent mediator in a poly(vinyl chloride) membrane matrix exhibited a near-Nernstian response to Pb2+ in the concentration range from 3 × 10−6 to 1 × 10−2 M with a slope of 30.1 mV per concentration decade in a solution containing 0.1 M Mg(NO3)2. The limit of detection was 9 × 10−7 M. The ion selectivity of this electrode for Pb2+ was over 104 times that for Mg2+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+ or Cd2+. Such high sensitivity and selectivity were comparable to the best case in many Pb2+-selective electrodes so far developed.