The preparation of a lead-selective electrode based on 5,11,17,23-tetra-
tert-butyl-25,26,27,28-tetrakis-(diphenylphosphinoylmethoxy)calix[4]arene (
1) as an ionophore is reported. The plasticized PVC membrane containing 30% PVC, 57%
ortho-nitrophenyloctylether (NPOE), 4% sodium tetraphenylborate (NaTPB) and 9% ionophore
1 was directly coated on a graphite electrode. It exhibits a nearly Nernstian slope of 28.0 ± 0.2 mV decade
-1 over a concentration range of 1 × 10
-5 - 1 × 10
-2 mol dm
-3 with a detection limit of 1.4 × 10
-6 mol dm
-3. The response time of the electrode was found to be
ca. 17 s. The potential of the sensor was independent of the pH variation in the range 3.5 - 5.0. The selectivity of the electrode performance towards lead ions over Th
4+, La
3+, Sm
3+, Dy
3+, Y
3+, Ca
2+, Sr
2+, Cd
2+, Mn
2+, Zn
2+, Ni
2+, Co
2+, NH
4+ Ag
+, Li
+, Na
+ and K
+ ions was investigated. The prepared electrode was used successfully as an indicator electrode for a potentiometric titration of a lead solution using a standard solution of EDTA. The applicability of the sensor for Pb
2+ measurements in various synthetic water samples spiked with lead nitrate was also checked.
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