Ion Selective Membrane Electrodes for Stability Indicating Determination of Benoxinate Hydrochloride in Pure form and in Drug Product

This paper presents a comparative study between four sensorsconstructed to determine benoxinate hydrochloride (bx) in the presence of its hydrolysisinduced degradation product using different ion association complexes and plasticizers.precipitation based technique was used for sensors fabrication. the bx complexes with thecationic exchangers; bx- reinikate, bx-tetraphenylborate, bx-phosphotungestate, and bxtetrakiswere obtained in situ by soaking the pvc membranes in 1×10-2 bx solution.dioctylphthalate and nitrophenyl octyl ether were used as solvent mediators. the proposedsensors showed fast, stable nernstian responses across a relatively wide bx concentrationrange (5×10-5 to 10-1 m) in the ph range of 4-6. the suggested sensors could be used forseveral weeks without any measurable change in sensitivity. they displayed good selectivityfor bx in presence of its degradation product, common inorganic and organic species. theproposed sensors were successfully applied for the determination of bx in pure powder formand eye drops where good recoveries were obtained.