Lead (II) ion selective electrodes based on diphenylmethyl-N-phenylhydroxamic acid ionophore in cyanocopolymer matrix

A Pb/sup 2+/ ion selective electrode has been prepared using diphenylmethyl-N-phenylhydroxamic acid (DPNINPRA) as ionophore and cyanocopolymer as new membrane matrix. The electrode (Membrane-2) exhibited a Nernstian slope of 36.75/spl plusmn/0.001 mV decade/sup -1/ activity of Pb/sup 2+/ ions on varying the Pb/sup 2+/ ions activity from 7.41/spl times/10/sup -8/ to 3.68/spl times/10/sup -1/ mol dm/sup -3/. The electrode has exhibited a response time of 13.0/spl plusmn/s at 1.0/spl times/10/sup -3/ mol dm/sup -3/ activity of Pb/sup 2+/ ions and also revealed an improved selectivity in presence of various interfering ions. The high dipolar property of the selected cyanocopolymer has reduced significantly the anions interference and shown potential response independent to the activity of sodium tetraphenylborate (NaTPB). The electrode has shown isothermal point of 30/spl deg/C as determined from a hysteresis curve. Sensitivity of the electrode has shown a significant variation with thickness of the membrane. The electrode has shown a constant response on continuous use for a period of six months without any drift in potential and has been also found to be useful as indicator electrode for potentiometric titration of Pb/sup 2+/ ions.