Manganese(II) ion-selective membrane electrode based on N-(2-picolinamido ethyl)-picolinamide as neutral carrier

Abstract

A new poly (vinyl chloride) (PVC) membrane electrode that is highly selective to Mn+2 ions was prepared using N,N'-bis(2'- pyridinecarboxamide)-1,2-ethane (bpenH2) as a suitable neutral carrier. This concentration range (1.0 × 10-5 to 1.0 × 10-1 M) with Nernstian slope of 29.3 ± 0.5 mV per decade. The detection limit and the response time of electrode were 8.0 × 10.6 M and (≤ 15 s) respectively. The membrane can be used for more than two months without observing any divergence. The electrodes exhibited excellent selectivity for Mn+2 ion over other mono-, di-and trivalent cations. Selectivity coefficients were determined by the matched potential method (MPM). The electrode can be used in the pH range from 4.0-9.0. The isothermal coefficient of this electrode amounted to 0.00023 V/°C. The stability constant (log Ks) of the Mn+2-bpenH2 complex was determined at 25 °C by potentiometric titration in mixed aqueous solution. The proposed electrode was applied to the determination of Mn+2 ions in real samples.