Ion Selective Electrodes for Potentiometric Determination of Baclofen in Pharmaceutical Preparations

Two different sets of baclofen sensors were developed for its potentiometricdetermination in pharmaceutical preparations, based on the fact that baclofen behaves ascation in acidic medium and anion in basic medium (pk1=9.62 and pk2=3.87;respectively).six baclofen- selective electrodes were investigated using precipitation based technique witheither sodium tetraphenyl borate as an anionic exchanger or 1, 10-ortho-phenanthrolineferrousas a cationic exchanger; respectively upon using polyvinyl chloride (pvc) matrix anddioctylsebacate (dos) as a plasticizer. the resultant sensors have different forms, either asmembrane electrodes (sensors i&iv), coated wire electrodes (sensors ii&v) or as microsizedgraphite electrodes (sensors iii&vi). linear responses of 10-6–10-2 m with slopes of 43.05,43.11, and 43.05 mv/decade within ph range 4-6 were obtained for sensors i, ii and iii. onthe other hand, linear responses of 10-7–10-3 m with slopes of 55.90, 57.13 and 57.37mv/decade within ph 6-8 range were obtained for sensors iv, v and vi; respectively.allthese sensors were prepared and fully characterized in terms of composition, life span, usableph range, response time and temperature. the sensors show good selectivity to the drug inpresence of a variety of inorganic and organic interferent substances. the proposedprocedures were compared to the usp pharmacopoeial method and showed no significantdifference. the proposed sensors displayed useful analytical characteristics for thepotentiometric determination of baclofen in pure form and in pharmaceutical preparations.