A Comparative Study of Ag+-Selective Electrodes Based on Two 21-Membered N3S4-Macrocycles as Neutral Ionophores

The performances of two 21-membered N3S4-azathiacrown ethers as neutral carriers for Ag+-selective electrodes (Ag+-ISEs) were investigated. Potentiometric responses revealed that the flexibility of the crown ether has great effect on the selectivity and sensitivity of sensors to Ag+. The addition of ion-exchanger and different plasticizers has also been found to substantially improve the performance of the Ag+-ISEs. With the optimal conditions, the electrode based on ionophore derived from benzene-1, 2-dithiol gives a better response and reveals a Nernstian behavior over a wide concentration range of 3.0 x 10(-7) -3.0 x 10(-3) M with a detection limit of 6.7 x 10(-8) M Ag+. The electrode possesses advantages of low resistance, very fast response time, long lifetime and, especially, good selectivity relative to a wide variety of other cations. The potentiometric responses are independent of the pH of the test solution in the pH range 3.0-8.9. The electrode can be used as indicator electrode in the potentiometric titration of Cl-in tap water and spiked water.The performances of two 21-membered N3S4-azathiacrown ethers as neutral carriers for Ag+-selective electrodes (Ag+-ISEs) were investigated. Potentiometric responses revealed that the flexibility of the crown ether has great effect on the selectivity and sensitivity of sensors to Ag+. The addition of ion-exchanger and different plasticizers has also been found to substantially improve the performance of the Ag+-ISEs. With the optimal conditions, the electrode based on ionophore derived from benzene-1, 2-dithiol gives a better response and reveals a Nernstian behavior over a wide concentration range of 3.0 x 10(-7) -3.0 x 10(-3) M with a detection limit of 6.7 x 10(-8) M Ag+. The electrode possesses advantages of low resistance, very fast response time, long lifetime and, especially, good selectivity relative to a wide variety of other cations. The potentiometric responses are independent of the pH of the test solution in the pH range 3.0-8.9. The electrode can be used as indicator electrode in the potentiometric titration of Cl-in tap water and spiked water