A Potentiometric Sensor for the Determination of Pb(II) Ions in Different Environmental Samples

In this study, a novel PVC-based membrane containing (E)-2-(1-(4-(3-(4-chlorophenyl)ureido)phenyl)ethylidene)hydrazine carbothioamide (5) as an electroactive component (ionophore) along with potassium tetrakis (p-chlorophenyl) borate (KTpClPB) and bis(2-ethylhexyl)adipate (DEHA) in the ratio 4.0 : 32.0 : 1.0 : 63.0 (ionophore:PVC:KTpClPB:DEHA) (w/w) was used to develop a lead(II)-selective potentiometric sensor. The sensor exhibited a Nernstian response over a wide concentration range from 1.0x10(-5) to 1.0x10(-1) mol L-1 with a slope of 28.0 +/- 2.0 mV/decade, and a detection limit of 1.65x10(-6) mol L-1. It displayed very good selectivity towards Pb(II) ions over other cationic species. The lead(II)-selective sensor showed a fast response time of 5 s, good repeatability, and it worked in the broad pH range of 5.0-11.0. The sensor could be used as an indicator electrode in the quantification of Pb(II) by potentiometric titration against ethylenediaminetetraacetic acid (EDTA). In addition, this sensor was applied for the direct determination of Pb(II) in different water samples including spring water, purification water, commercial water, waste water and in a waste battery sample.