Sensor for silver(I) ion based on Schiff-base-p-tertbutylcalix[4] arene

The preparation of polymer membrane selective to silver ion and its application to ion-selective electrode is reported here. PVC membrane contain silver-selective calix[4] arene derivative as ionophore. The membrane electrode is highly selective to silver ion and exhibit good linear response over a wide concentration range of 1.0 x 10(-1) to 1.0 x 10(-5)M AgNO3 with Nernstian slope of 58.9 mV per decade. The detection limit of electrode is 6.31 x 10(-6) M. The calix[4] arene based membrane electrode exhibit enhanced selectivities for silver ion over other cations; log K-Ag,Na(Pot) = -2.35, log K-Ag,K(Pot)= - 2.65, log K-Ag,Mg(Pot) = - 4.57, log K-Ag,Ba(Pot) = -4.10, log K-Ag,Cd(Pot) = - 3.42, log K-Ag,Pb(Pot) = - 3.45. Even the strongest interferent Hg2+ do not interfere to great extent, log K-Ag,Hg(Pot) = -2.0. The electrode response is stable over wide pH range of 1.0-6.0. The response time of the sensor is 30 seconds and the membrane can be used for more than 6 months without observing any divergence. The sensor can also be applied as an indicator electrode for potentiometric titration of Ag+ ions with Cl-. It is possible to determine Ag(I) in the natural water spiked with silver with this electrode assembly.