Reproterol plastic membrane ion-selective electrodes based on its individual and mixed ion-exchangers with phosphotungstic and/or phosphomolybdic acids

Reproterol hydrochloride (RpCl), selective PVC membranes based on ion associates of reproterolium-phosphotungstate (Rp-PTA); reproterolium-phospho-molybdate (Rp-PMA) or a mixture of both (Rp-PTA/PMA) were prepared. The electrodes displayed a linear response over the concentration range of 6.3×10⁻⁶–1.0×10⁻¹ mol dm⁻³ RpCl. The working pH ranges of the above electrodes were 2.5–9.0, 2.5–8.5 and 2.0–9.0 and their isothermal temperature coefficients were 0.00014, 0.00090 and 0.00103 V/°C, respectively. The electrodes showed good selectivity to the reproterolium ion with respect to many inorganic cations, sugars and amino acids. The standard additions and potentiometric titration methods were used to determine RpCl in pure solutions and in its pharmaceutical preparations with high accuracy and precision.