Effect of concentration of ion exchanger, plasticizer and molecular weight of cyanocopolymers on selectivity and sensitivity of Cu(II) ion selective electrodes

The potential response of cyanocopolymer based Cu2+ ion selective electrodes has been studied as a function of concentration of ionophore (Schiffʹs base complex), plasticizer (dioctylphthalate) and molecular weight of the cyanocopolymers. The concentration variation in electrode constituents has shown significant effect on the sensitivity, selectivity, detection limits, response time and extent of interference from foreign ions during potentiometric measurements of electroactive ions. Hydrophobic nature and high dipole moment of the employed cyanocopolymers have enhanced the average lifetime of the electrode and shown least interference from solution anions. Electrodes prepared with optimum amount of the ionophore (2.7×10-2molkg-1), plasticizer (2.1×10-3molkg-1) and cyanocopolymers (2.0g) of molecular weight 59.565kgmol-1 have shown a Nernstian slope of 27.59±0.053mV per decade activity of the Cu2+ ions with a response time of 13.00±0.002s. These electrodes with optimized amount of constituents have shown working range of 2.5×10-7 to 1.0×10= 2moldm-3 activities of the Cu2+ ions. The electrodes response as a function of concentration variation of ionophore, plasticizer and molecular weights of cyanocopolymers have been explained in terms of ionophore interaction energy and plasticization of the polymer matrix.