ION-SELECTIVE MEMBRANE SENSORS FOR DETERMINATION OF BRIMONIDINE TARTRATE IN BULK POWDER, PHARMACEUTICAL EYEDROPS AND BIOLOGICAL FLUIDS

Three novel brimonidine tartrate (BRD) selective electrodes were investigated with di-octyl phthalate as a plasticizer in a polymeric matrix of polyvinyl chloride (PVC). Sensor 1 was fabricated using phosphotungestic acid (BRD-PTA), while sensor 2 was constructed using phosphomolybdic acid (BRD-PMA), whereas sensor 3 was constructed using sodium tetraphenyl borate (BRD-TPB) as ionophores. Linear responses of BRD within the concentration ranges of 10−7 to 10−2 mol/l for sensors 1, 2 and 3 were observed. Nernstian slopes of 31.88, 29.83 and 28.50 mv/decade were observed over the pH range of 3-5 for sensors 1, 2 and 3, respectively. The selectivity coefficients of the developed sensors indicated excellent selectivity for BRD. The proposed sensors displayed useful analytical characteristics for the determination of BRD in bulk powder, pharmaceutical formulation and biological fluids (plasma and urine). The novel electrodes offer the advantage of determination of BRD in biological fluids without pretreatment which is convenient for monitoring BRD levels in clinical studies.