Comparative study of different potentiometric ion-selective electrodes for determination of certain polyionic drugs

Abstract

Selective polyionic electrodes were investigated; using precipitation based technique forming ion-pair complexes between the polycation Polymyxin B (Poly B) and tetrakis (4-chlorophenyl) borate (TpClPB) (sensor 1) and phosphotungstic acid (sensor 2) and ionophore based technique with 2-hydroxy propyl beta cyclodextrin (HP β-CD) (sensors 3 and 4) for determination of Poly B and Cromolyn sodium (CS), respectively. Also an aqueous dispersion of iron oxide magnetic nanoparticles (NPs) was applied with (HP β-CD) for CS determination (sensor 5). Linear responses within concentration ranges of 10-6 to 10-2, 10-6 to 10-3, 10-7 to 10-4 and 10-6 to 10-3 mol L-1 were achieved, using sensors 1, 2, 3 and 4, respectively. On the other hand the sensitivity was increased up to 10-8 mol L-1 on using sensor 5. Near nernstian slopes of 12.68, 53.55, 58.93 and 55.11 mV/decade were observed for sensors 1, 2, 3 and 4, respectively, and an ideal nernstian slope of 59.60 mV/decade was obtained for sensor 5. The developed sensors 1, 2, 3 and 4 showed a reasonable selectivity, whereas the selectivity of sensor 5 was the greatest one. The proposed sensors showed successful application for determination of the investigated drugs in pharmaceutical formulations and biological fluids without pretreatment.