Abstract:
Two different sets of baclofen sensors were developed for its potentiometric
determination in pharmaceutical preparations, based on the fact that baclofen behaves as
cation 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 with
either sodium tetraphenyl borate as an anionic exchanger or 1, 10-ortho-phenanthrolineferrous as a cationic exchanger; respectively upon using polyvinyl chloride (PVC) matrix and
dioctylsebacate (DOS) as a plasticizer. The resultant sensors have different forms, either as
membrane electrodes (sensors I&IV), coated wire electrodes (sensors II&V) or as microsized
graphite 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. On
The other hand, Linear responses of 10-7–10-3 M with slopes of 55.90, 57.13 and 57.37
mV/decade within pH 6-8 range were obtained for sensors IV, V and VI; respectively.All
these sensors were prepared and fully characterized in terms of composition, life span, usable
pH range, response time and temperature. The sensors show good selectivity to the drug in
presence of a variety of inorganic and organic interferent substances. The proposed
procedures were compared to the USP pharmacopoeial method and showed no significant
difference. The proposed sensors displayed useful analytical characteristics for the
potentiometric determination of baclofen in pure form and in pharmaceutical preparations.
