POTENTIOMETRIC SENSORS BASED ON ION-SELECTIVEELECTRODES ARE ESPECIALLY SUITEDFOR DETERMINATION OF SEVERAL CHEMICAL SPECIES BECAUSE THEY OFFER ADVANTAGES SUCH AS SELECTIVITY, SENSITIVITY, GOOD PRECISION, SIMPLICITY, AND LOW COST.NOWADAYS, CHEMICAL SENSORS HAVE ATTRACTED CONSIDERABLE ATTENTION BECAUSE OF THEIR FAVOURABLE PORTABILITY, SIMPLE OPERATION AND SUITABILITY FOR ON-SIT MONITORING. WITH THE POTENTIOMETRIC TRANSDUCTION MODE, POLYMERIC MEMBRANE ION SELECTIVE ELECTRODES (ISES) HAVE FOUND WIDESPREAD USE ININDUSTRIAL, CLINICAL AND ENVIRONMENTAL ANALYSIS OWING TO THEIR ADVANTAGES SUCH AS GOOD SELECTIVITY, LOW COST OF PREPARATION, RAPIDITY AND EASINESS OF MEASUREMENT AND HIGH RELIABILITY [1].

ERYTHROMYCIN ESTERS SUCH AS ETHYLSUCCINATEIS ANTIBACTERIALLY INACTIVE AND ONLY BECOMES EFFECTIVE AFTER IT IS HYDROLYZED TO ERYTHROMYCIN IN PLASMA AND OTHER BODY STUIDS.ERYTHROMYCIN PREVENTS PROTEIN SYNTHESIS AT BACTERIAL RIBOSOMES, RESULTING IN THE DEATH OF THE ORGANISM [1].DIFFERENT ANALYTICAL METHODS HAVE BEEN DEVELOPED FOR THE DETERMINATION OF ERYTHROMYCIN ETHYLSUCCINATE AND ITS METABOLITIES INCLUDING CHROMATOGRAPHY, SPECTROPHOTOMETRY AND VOLTAMMETRY [2, 3], THUS FOR EASY, FAST AND SELECTIVE DETERMINATION OF ERYTHROMYCIN ETHYLSUCCINATE, IN THIS STUDY A NEW CARBON PASTE ELECTRODE BASED ON THE USE OF ION ASSOCIATION COMPLEX OF ERYTHROMYCIN ETHYLSUCCINATE WITH PHOSPHOTUNGSTATE IS CONSTRUCTED.HOWEVER, NO ISE FOR THIS DRUG WAS REPORTED.THE MOST ADVANTAGES OF CPES ARE EASE OF PREPARATION, MODIFICATION AND REGENERATION AND SPECIALLY LOW COST.THE PROPOSED ELECTRODE EXHIBITS A NERNSTIAN SLOPE OF 59.0±0.2 MV/DECADE FOR ERYTHROMYCIN ETHYLSUCCINATE OVER A CONCENTRATION RANGE OF 7.4×10-8-1.0×10-3 M, WITH A DETECTION LIMIT OF 5.0×10-8 M. THE ELECTRODE HAS A FAST RESPONSE TIME (<5 S), SATISFACTORY REPRODUCIBILITY AND GOOD LIFE TIME (MORE THAN 2 MONTHS). THE POTENTIOMETRIC RESPONSE OF THE ELECTRODE WAS STUDIED IN BUFFERED SOLUTION. THE INFLUENCE OF THE TEMPERATURE ON THE RESPONSE OF THE ELECTRODE WAS INVESTIGATED AND THE TEMPERATURE COEFFICIENT OF THE ELECTRODE WAS CALCULATED BY RECORDING THE CALIBRATION GRAPHS AT DIFFERENT TEMPERATURES. THE ELECTRODE WAS APPLIED IN POTENTIOMETRIC TITRATION OF ERYTHROMYCIN ETHYLSUCCINATE SOLUTION ALSO AND DETERMINATION OF ERYTHROMYCIN ETHYLSUCCINATE IN TABLET AND BLOOD SERUM SAMPLES.

SUMATRIPTAN SUCCINATE IS AN AGONIST FOR A VASCULAR 5-HYDROXYTRYPTAMINE RECEPTOR SUBTYPE USED IN THE TREATMENT OF ACUTE MIGRAINE EPISODES. IT WAS THE FIRST OF THE SO-CALLED ‘‘TRIPTAN’’ DRUGS WHICH HAVE HAD A SIGNIFICANT IMPACT ON THE TREATMENT OF ACUTE ATTACKS. DIFFERENT ANALYTICAL METHODS HAVE BEEN DEVELOPED FOR THE DETERMINATION OF SUMATRIPTAN SUCCINATE INCLUDING CHROMATOGRAPHY AND SPECTROPHOTOMETRY, WHICH ARE EITHER TIME-CONSUMING OR REQUIRE EXPENSIVE AND SOPHISTICATED INSTRUMENTS. THUS, THE INTRODUCTION OF AN ISE FOR FAST, SIMPLE AND SELECTIVE DETERMINATION OF SUMATRIPTAN SUCCINATE IS AN URGENT NEED. HOWEVER, NO ISE FOR THIS DRUG WAS REPORTER SO FAR. IN THIS WORK, A NEW CARBON PASTE ELECTRODE (CPE) BASED ON THE USE OF ION ASSOCIATION COMPLEX OF SUMATRIPTAN SUCCINATE CATION WHIT PHOSPHOTANGESTATE IS CONSTRUETED. THE PROPOSED ELECTRODE EXHIBITS A NERNSTIAN SLOPE OF 58.4±0.3 MV PER DECADE FOR SUMATRIPTAN SUCCINATE OVER A WIDE CONCENTRATION RANGE OF 5.0×10-8- 1.25×10-5 M, WITH A LOW DETECTION LIMIT OF 3.5×10-8 M. THE ELECTRODE HAS A RELATIVELY FAST RESPONSE TIME (9 S) SATISFACTORY REPRODUCIBILITY AND GOOD LIFE TIME (MORE THAN 2 MONTHS). THE POTENTIOMETRIC RESPONSE CHARACTERISTICS OF THE ELECTRODE WAS STUDIED IN BUFFERED SOLUTIONS. POTENTIOMETRIC TITRATION OF SUMATRIPTAN SUCCINATE SOLUTION WITH TETRAPHENYLBORATE AS A TITRANT HAS BEEN MONITORED WITH THE PROPOSED SENSOR AS AN INDICATOR ELECTRODE. THE ELECTRODE WAS SUCCESSFULLY APPLIED TO DETERMINE SUMATRIPTAN SUCCINATE IN SUMATRIPTAN SUCCINATE TABLET AND ALSO BLOOD SERUM SAMPLES. THE INCLUSION COMPLEX FORMATION BETWEEN CYCLODEXTRINES AND SUMATRIPTAN SUCCINATE WAS STUDIED POTENTIOMETRICALLY AND EQUILIBRIUM CONSTANT OF THE COMPLEXES WERE CALCULATED.