4-( 4-Methoxybenzilidenimin) Thiophenole as Neutral Carrier for Construction of Highly Mercury Selective Electrode

Department of Chemistry, University of Yasooj, Yasouj 75914-353, Iran, m_ghaedi@mail.yu.ac.ir

Absrtract
Highly selective poly (vinyl chloride) (PVC) membrane electrodes based on 4-( 4- methoxybenzylidenimin) thiophenole as new carrier for mercury-selective electrode has been reported. The electrode was prepared by coating the membrane ingredient on the surface of graphite electrode. The effect of various parameters including, the membrane composition, pH and possible interfering ions on the response properties of the electrode were examined. The sensor exhibited Nernstian responses toward mercury over a wide concentration range from 2×10^-6 to 0.1 M, with slopes of 29.24 ± 0.82 mV per decade of mercury concentration, over a wide pH range of 1.3 – 2.9. The limit of detection for electrode was 8×10^-7 M. The sensor has stable responses times of £10 s after conditioning in 0.05 M Hg (NO₃)₂ for 18 h and can be used for at least 2 months without any considerable divergence in the potential response characteristics. The proposed electrode show fairly good discrimination of mercury over several inorganic ions. The MBITP dissociation constant and the stability constant of its complex with mercury using Kim fit program in tetrahydrofuran (THF) has been calculated. The electrodes were successfully applied to direct determination of mercury in some real sample with complicated matrix and as indicator electrode in complexation titrations.

Keywords: Mercury-selective electrode; Potentiometry; Poly (vinyl Chloride) (PVC) membrane; 4-( 4- Methoxybenzilidenimin) thiophenole (MBITP).