Preparation and Application of Potassium Ion-Selective Membrane Electrode Based on Benzo-15-Crown-5 Ether

Abstract

A new potassium ion-selective membrane electrode has been developed based on crown ether. The membrane consisted of benzo-15-5 crown ether as a neutral carrier, orto-nitrophenylphenyl ether as plasticizer and PVC as membrane matrix. An analytically useful potential change occurs in the 1x10 -6 -1x10 -2 mol L -1 concentration range. The slope of the linear portion (1x10 -2 -1x10 -4 mol L -1 ) was 56 ± 3 mV/10-fold concentration changes in potassium concentration.In the presence of 1x10 -3 mol L -1 potassium, no interference was observed for Li + , Na + , NH 4 + , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Cr 3+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , F -, Br -, I -, NO 2 -, SO 4 2-, CO 3 2-, S 2-ions. The measurements were made at constant ionic strength (0.1 mol L -1 NaNO 3 , medium) and at room temperature. The lifetime of the electrode was approximately 2 months, and the response time was about 20-30 seconds. This electrode has been used for the determination of potassium ion with standard addition method in orange juice, vitamin, and edible salt. The amount of K + found was 1.97 ± 0.06 mg/mL in orange juice, 0.420 ± 0.008 % (m/m) in vitamin tablet and 0.52 ± 0.08 % (m/m) in edible salt.