A Highly Sensitive Lead Potentiometric Sensor Employing Some Phenylsemicarbazide Derivates as lonophores Incorporated to a Poly(vinyl chloride) Matrix for Hazardous Lead Trace Determination

摘要

In the present work, the fabrication, characterization and feasibility of solvent polymeric membrane electrodes based on some derivates of phenylsemicarbazide such as 1-phenylsemicarbazide (1-PSC), 4-phenylsemicarbazide (4-PSC) and 1,4-diphenylsemicarbazide (1,4-DPSC) as potential ionophores, incorporated to PVC matrix have been demonstrated. In the presence of conventional inner filling solution of 1.0 × 10~(-4) molL~(-1) of Pb(NO_3)_2, the individual sensors containing (1,4-DPSC) revealed the best response characteristics respect to other sensors with a linear dynamic range between 1.7 × 10~(-1) to 5.0 × 10~(-8) molL~(-1). Also, an excellent Nernstian slope of 29.9 ± 0.3 mV per decade with the detection of limit 2.51 × 10~(-8) molL~(-1) was found. The best performance was obtained with the membrane composition containing 33% PVC, 64.5% TEHP, 1.5% NaTPB and 1% ionophore. The potential response of the sensors remained constant over the pH working range from 2.8-6.5. Also, Stabilization of lead ions activity on the low level at the inner side of the solvent polymeric membrane was carried out using EDTA as complexing agent. The upper linear Nernstian response range was shifted to 1.25 × 10~(-9) molL~(-1) with the detection of limit 6.31 × 10~(-10) molL~(-1). The sensors have been successfully used in the potentiometric titration of lead ion with sodium dichromate and determination of lead in some alloys, tape and waste water samples.