Membranes of 4-tert-butylcalix[4]arene (I) as an electroactive material, sodium tetraphenyl borate (NaTPB) as an anion excluder, and dibutyl phthalate (DBP) as solvent mediator in poly(vinyl chloride) (PVC) matrix have been tried for lead-selective sensor. The best performance was exhibited by the membrane having the composition 2 : 1 : 100 : 200 (I : NaTPB: DBP: PVC). This sensor works well in the concentration range 1.1×10−5–1.0×10−1 M with a Nernstian slope (30.0±1.0 mV/decade of activity). The working pH range of the sensor is 2.1–4.0 and it shows good selectivity for Pb(II) over other mono-, bi- and trivalent cations which are reported to cause interference in the working of other sensors. It works well in partially nonaqueous medium up to 30% (v/v) (methanol, ethanol and acetone) and exhibits a fast response time (11 s). The assembly could be used for six months without any change in potentials. The sensor has successfully been used as an indicator electrode in the potentiometric titration of Pb(II) against EDTA.
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Gupta et al. (2002) studied this question.