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].

IRON IS WIDELY DISTRIBUTED IN NATURE AND IS ONE OF THE MOST IMPORTANT ELEMENTS IN BIOLOGICAL SYSTEMS. BIOLOGICALLY IRON PLAYS IMPORTANT IN THE TRANSPORT AND STORAGE OF OXYGEN AND ALSO IN ELECTRON TRANSPORT. EXCESS IRON IN THE BODY CAUSES LIVER AND KIDNEY DAMAGE (HAEMOCHROMATOSIS). THE NEED FOR IRON ION DETERMINATION IN CLINICAL, MEDICINAL, ENVIRONMENTAL AND DIFFERENT INDUSTRIAL SAMPLES HAS LED TO A NUMBER OF METHODS FOR THE MEASUREMENT OF THIS ANALYTE. HOWEVER, DESPITE THE URGENT NEED FOR EASY, FAST AND SELECTIVE SENSORS FOR THE POTENTIOMETRIC MONITORING OF FE3+ IONS, THERE HAVE BEEN ONLY LIMITED REPORTS ON FE3+ ION-SELECTIVE ELECTRODES IN THE LITERATURE. IN THIS WORK, A RECENTLY SYNTHESIZED SCHIFF BASE LIGAND WAS STUDIED TO CHARACTERIZE ITS ABILITY AS CATION CARRIER IN PVC MEMBRANE ELECTRODE. THE CONSTRUCTED ELECTRODE SHOWED EXCELLENT RESPONSE CHARACTERISTICS TO FE3+ IONS. THE ELECTRODE EXHIBIT NERNSTIAN SLOPE OF 19.9±0.3 MV/DECADE OVER A WIDE CONCENTRATION RANGE OF 1.5×10-5-1.5×10-3 FE3+ IONS WITH LOW DETECTION LIMIT OF 9.0×10-7 M. THE ELECTRODE HAVE A FAST RESPONSE TIME (8 S), SATISFACTORY REPRODUCIBILITY, GOOD LIFE TIME (MORE THAN 2 MONTHS) AND EXCELLENT SELECTIVITY TOWARD FE3+ IONS. THE POTENTIOMETRIC RESPONSE OF THE ELECTRODE WAS STUDIED IN BUFFERED SOLUTION. THE ELECTRODE WAS SUCCESSFULLY APPLIED AS AN INDICATOR ELECTRODE IN POTENTIOMETRIC TITRATION OF FE3+ IONS AND ALSO DETERMINATION OF FE3+ IONS IN MINERAL WATER AND PHARMACEUTICAL PREPARATIONS.

CLARITHROMYCIN IS A MACROLIDE ANTIBIOTIC WHICH PREVENTS BACTERIAL GROWTH BY INTERFERING WITH PROTEIN SYNTHESIS. IT IS AN ACID-STABLE VERSION OF ERYTHROMYCIN AND IS PARTICULARLY EFFECTIVE AGAINST GRAM-NEGATIVE BACTERIA [1]. SEVERAL METHODS HAVE BEEN REPORTED FOR THE DETERMINATION OF CLA SUCH AS HIGH PERFORMANCE LIQUID CHROMATOGRAPHY WITH UV DETECTOR, FLUORESCENCE, MASS SPECTROMETRY AND ELECTROCHEMICAL [2, 3]. HOWEVER, MOST OF THESE METHODS ARE EITHER TIME-CONSUMING OR REQUIRE EXPENSIVE AND SOPHISTICATED INSTRUMENTS, WELL CONTROLLED EXPERIMENTAL CONDITIONS AND SOME SAMPLE PRETREATMENTS. THE INTRODUCTION OF AN ISE FOR FAST, SIMPLE AND SELECTIVE DETERMINAT ION OF CLARITHROMYCIN IS AN URGENT NEED. HOWEVER, NO ISE FOR THIS DRUG WAS REPORTED.IN THIS WORK, A NEW COATED WIRE PVC MEMBRANE ELECTRODE BASED ON THE USE OF ION ASSOCIATION COMPLEX OF CLARITHROMYCIN WITH PHOSPHOTUNGSTATE IS CONSTRUCTED. THE PROPOSED ELECTRODE EXHIBITS A NERNSTIAN SLOPE OF 59±0.3 MV/DECADE FOR CLA OVER A CONCENTRATION RANGE OF 2.2×10-7-1.0×10-2 M, WITH A LOW DETECTION LIMIT OF 1.0×10-7 M. THE ELECTRODE HAS A FAST RESPONSE TIME (<6 S), SATISFACTORY REPRODUCIBILITY AND GOOD LIFE TIME. 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 CLA SOLUTION AND DETERMINATION OF CLA IN TABLET AND BLOOD SERUM SAMPLES.

ION IMPRINTING IS A UNIQUE TECHNIQUE USED FOR PREPARING POLYMERS WITH SYNTHETIC RECOGNITION SITES HAVING A PREDETERMINED SELECTIVITY FOR ANALYTES OF INTEREST. IN RECENT YEARS, ION IMPRINTED POLYMERS (IIPS) HAVE GAINED WIDE ACCEPTANCE AS NEW ION RECOGNITION MATERIALS IN CHEMICAL SENSORS. POTENTIOMETRIC TECHNIQUE IS ALSO WELL-KNOW VERSATILE, SIMPLE, RAPID AND INEXPENSIVE METHOD FOR DETERMINATION OF TARGET ION. POTENTIOMETRIC TECHNIQUE IS ANOTHER APPROACH TO ELECTROCHEMICAL TRANSDUCTION OF ION SELECTIVE SENSORS BASED ON IIP.WITH THE POTENTIOMETRIC TRANSDUCTION MODE, POLYMERIC MEMBRANE ION SELECTIVE ELECTRODES (ISES) HAVE FOUND WIDESPREAD USE IN INDUSTRIAL, CLINICAL AND ENVIRONMENTAL ANALYSIS OWING TO THEIR ADVANTAGES SUCH AS GOOD SELECTIVITY, LOW COST OF PREPARATION, RAPIDITY AND EASINESS OF MEASUREMENT AND HIGH RELIABILITY.IN THIS STUDY, A POLYMERIC MEMBRANE ION-SELECTIVE ELECTRODE FOR DETERMINATION OF MERCURY (II) IS DESCRIBED. IT IS BASED ON A ION IMPRINTED POLYMER FOR ION RECOGNITION, WHICH CAN BE SYNTHESIZED WITH MERCURY (II) ACETATE AS MERCURY SALT, METHACRYLIC ACID AND 1, 3_DIMETHYLBARBITURIC ACID AS FUNCTIONAL MONOMERS, ETHYLENE GLYCOL DIMETHACRYLATE AS CROSS-LINKING AGENT AND AZOBISISOBUTYRONITRILLE AS AN INITIATOR. AND A NEW COATED WIRE ELECTRODE HAS BEEN DEVELOPED AS A MERCURY ION-SELECTIVE SENSOR. THE OPTIMIZED MEMBRANE INCORPORATING DOP, PVC AND IIP WAS DIRECTLY COATED ON THE SURFACT OF A PLATINUM WIRE ELECTRODE. THE EFFECTS OF THE PH AND POSSIBLE INTERFERING IONS WERE INVESTIGATED AND THE OPTIMIZED CONDITIONS FOR ELECTROD WERE EVALUATED.

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THE DETERMINATION OF PERCHLORATE IN DIFFERENT SAMPLES SUCH AS GROUND WATER, URINE AND PROPELLANT IS VERY IMPORTANT. DETERMINATION OF PERCHLORATE ION HAS BEEN CARRIED OUT DIRECTLY OR INDIRECTLY METHODES INVOLVING VOLUMETRIC TITRATIONS [1], SPECTROPHOTOMETRY [2] AND ION CHROMATOGRAPHY [3]. HOWEVER, MOST OF THESE METHODS SUFFER FROM VARIOUS INTERFERENCES AND ARE TIME CONSUMING OR NEED SOPHISTICATED INSTRUMENTS. HENCE, MAJOR EFFORTS HAVE BEEN MADE TO DEVELOP A DIRECT AND CONVENIENT METHOD FOR THE DETERMINATION OF PERCHLORATE ION. THEREFORE, THERE IS STILL AN URGENT NEED FOR HIGHLY SENSETIVE AND SELECTIVE ELECTRODES WHICH CAN BE USED FOR THE DETERMINATION OF PERCHLORATE IN DIFFERENT SAMPLES [4-6].IN THIS WORK, A NEW COATED WIRE PVC MEMBRANE ELECTRODE BASED ON A RECENTLY SYNTHESIZED SCHIFF BASE COMPLEX OF NI (II) AS SUITABLE CARRIER FOR CLO4-ION IS DESCRIBED. THE ELECTRODE EXHIBITS A NERNSTIAN RESPONSE OF 58.6 ± 0.3 MV PER DECADE FOR CLO4-ION OVER A WIDE CONCENTRATION RANGE FROM 1.5×10-7-4.4×10-2 M, WITH A DETECTION LIMIT OF 9×10-8 M. IT HAS A FAST RESPONSE TIME (<6 S), SATISFACTORY REPRODUCIBILITY AND LONG LIFE TIME (MORE THAN TWO MONTHS). THE PROPOSED SENSOR REVEALED GOOD SELECTIVITY TOWARD CLO4-WITH RESPECT TO DIFFERENT ANIONS INCLUDING HALIDES, THIOCIANATE AND NITRATE. THE POTENTIOMETRIC RESPONSE OF THE ELECTRODE IS INDEPENDENT OF THE PH OF TEST SOLUTION IN THE PH RANGE OF 3.0-10.0. THE PROPOSED SENSOR WAS USED IN POTENTIOMETRIC DETERMINATION OF PERCHLORATE ION IN MINERAL WATER AND BLOOD SERUM SAMPLES. THE VALUE (DE/DT) OF THE PROPOSED ELECTRODE WAS INVESTIGATED, WHICH INDICATES FAIRLY HIGH TERMAL STABILITY.

THE DETERMINATION OF PERCHLORATE IN DIFFERENT SAMPLES SUCH AS GROUND WATER, URINE AND PROPELLANT IS VERY IMPORTANT. THE DETERMINATION OF PERCHLORATE ION HAS BEEN CARRIED OUT DIRECTLY OR INDIRECTLY METHODES INVOLVING VOLUMETRIC TITRATIONS, SPECTROPHOTOMETRY AND ION CHROMATOGRAPHY.HOWEVER, MOST OF THESE METHODS SUFFER FROM VARIOUS INTERFERENCES AND ARE TIME CONSUMING OR NEED SOPHISTICATED INSTRUMENTS. HENCE, MAJOR EFFORTS HAVE BEEN MADE TO DEVELOP A DIRECT AND CONVENIENT METHOD FOR THE DETERMINATION OF PERCHLORATE ION. THEREFORE, THERE IS STILL AN URGENT NEED FOR HIGHLY SENSETIVE AND SELECTIVE ELECTRODES WHICH COULD BE USED FOR THE DETERMINATION OF PERCHLORATE IN DIFFERENT SAMPLES. IN THIS WORK, NEW COATED WIRE PVC MEMBRANE ELECTRODE BASED ON A RECENTLY SYNTHESIZED SCHIFF BASE COMPLEX OF NI (II) AS SUITABLE CARRIER FOR CLO4-ION IS DESCRIBED.THE ELECTRODE EXHIBITS A NERNSTIAN RESPONSE OF 58.2±0.3 MV PER DECADE FOR CLO4-ION OVER A WIDE CONCENTRATION RANGE FROM 7.5×10-8- 3.0×10-2 M, WITH A LIMIT OF DETECTION 3.8×10-8 M. IT HAS A FAST RESPONSE TIME (6 S), SATISFACTORY REPRODUCIBILITY AND LONG LIFE TIME (MORE THAN TWO MONTHS). THE PROPOSED SENSOR REVEALED GOOD SELECTIVITY TOWARD CLO4-WITH RESPECT TO DIFFERENT ANIONS INCLUDING HALIDES, THIOCIANATE AND NITRATE. THE POTENTIOMETRIC RESPONSE OF THE ELECTRODE IS INDEPENDENT OF THE PH OF TEST SOLUTION IN THE PH RANGE OF 2.0-12.0. THE PROPOSED SENSOR WAS USED IN POTENTIOMETRIC DETERMINATION OF PERCHLORATE ION IN TAP WATER AND BLOOD SERUM SAMPLES. THE INTERACTION OF THE IONOPHORE WITH CLO4- ION WAS INVESTIGATED BY UV/VIS SPECTROSCOPY.