Lead(II) ion selective poly(aniline) solid contact electrode based on 1,2-bis(N'-benzoylthioureido)ethane, -propane and -butane ionophores

Abstract

The lead ion selective electrodes were manufactured by synthesizing a benzoyl thioureido group ionophores having two sulfur groups on the both ends of ethane, propane and butane molecules. The ionophore containing propane moiety showed the best responsivity to lead ion. With the 1,3-bis(N,N'-benzoylthioureido)propane (BTP) ionophore, the best result was found when it included with the o-nitrophenyloctylether (o-NPOE) plasticizer with the highest permittivity and the oleic acid (OA) additive. The ratio of BTP: polyvinyl chloride: o-NPOE: potassium tetrakis(4-chlorophenyl)borate: OA was 2.5: 16.5: 30.5: 1.5: 0.5, the response range was 1.0 x 10(-6.4)-1.0 x 10(-1.0) M, and the response slope was 30.4 mV/decade. Addition of OA led to an excellent result for the responsivity, cation interference effect, correlation coefficient, response time and reproducibility. The electrode represented constant characteristics irrelevant to variation of pH between 2-7, the stabilization time was 30 s, the response time was about 30 s, and the reproducibility represented +/- 0.81 and +/- 1.40 mV for 1.0 x 10(-2.0) and 1.0 x 10(-3.0) M lead, respectively.