Sensor for Silver(I) Ion Based on Schiff-base-p-tertbutylcalix[4]arene

Abstract: 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 1.0×10^-1 to 1.0×10^-5M AgNO₃ with Nernstian slope of 58.9 mV per decade. The detection limit of electrode is 6.31×10^-6 M .The calix[4]arene based membrane electrode exhibit enhanced selectivities for silver ion over other cations; log K^Pot_Ag,Na = -2.35, log K^Pot_Ag,K= -2.65, log K^Pot_Ag,Mg = -4.57, log K^Pot_Ag,Ba = -4.10, log K^Pot_Ag,Cd = -3.42, log K^Pot_Ag,Pb = -3.45.Even the strongest interferent Hg²⁺ do not interfere to great extent, log K^Pot_Ag,Hg = -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.