Tin(II)-selective membrane potentiometric sensor using a crown ether as neutral carrier

A PVC membrane Sn(II)-ion-selective electrode has been constructed using dibenzo-18-crown-6 (DB18C6) as membrane carrier. The sensor shows a near Nernstian response for Sn(II) ions over a concentration range from 1.0 × 10−6 to 1.0 × 10−2 M with a slope of 27.5 ± 0.6 mV per concentration decade in an acidic solution (pH = 1). The limit of detection was 8.0 × 10−7 M. It has a response time of <15 s and can be used for at least 3 months without any divergence in potentials. The proposed membrane electrode revealed very good selectivity for Sn(II) ions over a wide variety of other cations and could be used in acidic media. The isothermal temperature coefficient of this electrode amounted to 0.0012 V/°C. The stability constant (log Ks) of the Sn(II)-DB18C6 complex was determined at 25 °C by potentiometric titration in mixed aqueous solution. It was used as indicator electrode in potentiometric determination of Sn(II) ion in real sample.