Potentiometric, Enantioselective Electrode Responsive to Propranolol Enantiomers Based on a Lipophilic β‐Cyclodextrin

Abstract

Potentiometric, enantioselective electrodes responsive to R(+)‐ and S(−)‐propranolol were constructed, based on a lipophilic cyclodextrin, 2‐hydroxy‐3‐trimethylammoniopropyl‐β‐cyclodextrin as an ionophore. Different plasticizers, ortho‐nitrophenyl octyl ether (o‐NPOE) and bis(t‐butylphntyl) adipate (BBPA), and inner filling solutions were studied. Electrode A, prepared with O‐NPOE as a plasticizer, and 1.0 × 10⁻³ M R‐enantiomer solution as an inner filling solution, has a sensitivity of 59.1 mV decade⁻¹, with a limit of detection, −log a = 4.92. Electrode B, prepared with BBPA as a plasticizer and 1.0 × 10⁻³ M NH₄Cl as an inner filling solution, shows a sensitivity of 60.0 mV decade⁻¹, with a limit of detection, −log a = 5.28. Inorganic cations (Na⁺, K⁺, Ca²⁺, Zn²⁺) and racemic and R‐sabutamol did not interfere with the measurement. The enantioselectivity coefficient (K_± ^pot), determined in 1.0 × 10⁻³ M appropriate enantiomer solutions, was 0.20.