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Abstract
The subject of this thesis is the preparation, characterization and application of some novel electrochemical sensors for the analysis of some industrial product and environmental pollutants.
Chapter one: includes a general introduction on potentiometry, the basic principles, theory, historical background characteristics and classification of potentiometric sensors.
Chapter two: describes a novel polymeric membrane sensor for thiocyanate ion using a recently new synthesized aryl palladium complex as ionophore in a PVC matrix. Fast Nernstian slope of -57.8 mV/ decade of thiocyanate ions over the concentration range of 1.0x10-6-1.0x10-1 M. The lower detection limits is 6.3 x10-7 M. Good selectivity for thiocyanate ion over various other anions is obtained. The potentiometric response is unaffected by pH variation over the pH range 4-10. The developed sensor is used for determination thiocyanate level in wide variety of biological samples like urine and saliva of cigarette smokers and non cigarette smoker. The sensor is also used as indicator electrode for potentiometric titrations of thiocyanate ion with Ag+.
Chapter three: describes new potentiometric and spectrophotometric methods for the determination of dodecyl sulphate ion [SDS]. In potentiometric method, an ion selective membrane sensor incorporating cobalt phthalocyanine as an electroactive species for dodecyl sulphate ion is developed. Good detection limit, sensitivity, accuracy and fast response time are obtained. The spectrophotometric assay depends on the formation of an ion association with cobalt phthalocyanine, reagent which associated with a decrease in the absorbance of the reagent with the increase of SDS concentration.
Chapter four: deals with a detailed study for construction, characterizations and applications of novel polymeric membrane sensor for determination of cadmium (II), based on the use of tetrathiophene porphyrin as sensing material and o-NPOE, DOS or DOP as solvent mediators. The proposed sensor exhibits significantly enhanced response towards cadmium (II), with high selectivity over a wide variety of metal ions. Fast Nernstian slope 27.2 mV/decade for Cd (II) ions over the concentration range of 2.5x10-6-1.0x10-2 M with a lower detection limits of 9.2x10-7 M. The sensor is used of pH range 3.0- 7.0. Application of the sensor for Cd determination in some alloys by direct potentiometric gives results agree fairly well with obtained by atomic absorption spectrometry.
Chapter five: describes a novel polymeric membrane sensor iodide ion using recently synthesized manganese tetrathiophene porphyrin as electroactive material in a PVC matrix. Fast Nernstian response for iodide ions over the concentration range of 2.5x10-6-1.0x10-2 M with a lower detection limit of 5 x10-7 M. The sensor exhibits Nernstian response with a slope of - 56 mV/ decade. Good selectivity for iodide ion over various other anions is obtained. The potentiometric response is constant over the pH range 2-8. The developed sensor is used for simultaneous determination of some metal ions such as Hg++ and Ag+ by potentiometric titrations. The curves obtained show consecutive inflection breaks corresponding stoichiometric equivalent points. The developed sensor is used for determination of iodide in some pharmaceutical preparations such as povidone- iodine solutions.
Chapter six: describes two novel polymeric membrane sensors responsive to levamisole hydrochloride (LV) drug. The sensors are characterized, compared and used for drug assessment. The sensors are based on the use of the ion-association complexes of (LV) cation with tetraiodomercurat) and reineckate anions as electroactive materials in plasticized poly (vinyl chloride) membranes. The sensors demonstrate fast near-Nerstian response for LV over the concentration ranges of 2 x10-6- 1.0x10-1 and 2.50x10-5-10-1 M with detection limits of 0.21 and 2.4 ?g ml-1 over the pH 3 - 6 for reineckate and tetraiodomercurate based membrane sensors respectively. The sensors display good selectivity for LV drug over many inorganic cations, excipients and diluents commonly used in drug formulations. Validation of the assay methods with both sensors by measuring the lower detection limit, range, accuracy, precision, repeatability and between-day-variability reveals good performance characteristics. The results confirm the applicability of the sensor for continuous determination of levamisole hydrochloride (LV) in pharmaceutical formulations.