الفهرس | Only 14 pages are availabe for public view |
Abstract Chapter I Comprises an introduction to explain the important concepts, classification of ion selective electrodes (ISEs) and their applications in variety of fields. Also explains the principles of the flow injection analysis (FIA), Dispersion, Detection and their applications. Chapter II Describes the construction of the Risperidone (RISH+ ) selective electrode , based on PVC matrix membrane containing RISH+ -tetraphenylborate ion pair as the electroactive component and DBP and O-NPOE as plasticizers. The electrodes exhibit near Nernstian response to RISH+ over the concentration range 1x10-5 to 10-2 mol L-1 and detection limit of 2.1x10-6 and 3.2x10-6 molL-1 for DBP and ONPOE membrane based electrodes, respectively. The electrodes offer many advantages that include; long lifetime (1.5 months), excellent stability and reproducibility, fast response time ( <15 s), high thermal stability (isothermal coefficient 0.34 mV/°C) and superior selectivity for RISH+ over a large number of inorganic and organic substances. The flow injection technique offers a sampling frequency of about ~60 samples h-1 . The electrode was successfully used as indicator electrode in the potentiometric titration of RIS versus tetraphenylborate (TPB) and in the determination of RIS in pharmaceutical preparations applying both batch and flow injection techniques. Average recoveries of 99.63 ± 0.6 and 99.4 ± 2.3 were obtained for Sigmadone and Psychodal tablets, respectively. The results are comparable with those obtained with a modified HPLC method. iv Chapter III Solid contact potentiometic sensors based on heptakis (2,3,6-tri-omethyl)-β-CD were fabricated for flow potentiometric determination of risperidone (RIS). Electrode matrices composition were optimized referring to the effect of type and content of the sensing ionohore, anionic sites and plasticizer. Silver and graphite coated wire electrodes incorporated with heptakis (2, 3, 6-tri-o-methyl) β-CD as sensing ionophore, potassium tetrakis (4-florophenyl) borate (KTFPB) as anionic site and o-nitrophenyloctyl ether (o-NPOE) as electrode plasticizer showed the best electroanalytical performances. The fabricated electrodes worked satisfactorily in the concentration range from 5×10-6 to 10-2 mol L- 1 with Nernstian compliance of 59.9 ± 0.7 mV decade-1 of detection limit 1x10-6 mol L-1 and response time of 5s. The developed sensors possessed improved selectivity, towards risperidone. The sensors have been successfully applied for the potentiometric determination of RIS in pharmaceutical preparations under both flow injection analysis (FIA) and potentiometric titration. Chapter IV A simple, rapid and sensitive method for the spectrophotometric determination of risperidone (RIS) in pure and true solutions has been developed. The proposed method is based on the charge–transfer reactions of risperidone as electron donors, with 7,7,8,8,-tetracyanoquinodimethane(TCNQ),2,3-dichloro-5,6-dicyano-1,4- benzoquinone (DDQ), tetracyanoethylene (TCNE) and chloranilic acid(CA) as π-acceptors to give colored complexes. The experimental conditions such as reagent concentration, reaction solvent, temperature v and time have been optimized to achieve the highest sensitivity. Beer’s law is obeyed over the concentration ranges of 8 – 150, 25 – 250, 5 – 70 and 10 – 110 µgml-1 risperidone using DDQ, CA, TCNE and TCNQ respectively, with corresponding correlation coefficients of 0.9995, 0.9993, 0.9990 & 0.9997 and detection limits of 3.62, 8.66, 1.93 and 2.85 µgml-1 for the reagents in the same order. Key words: Risperidone, Sigmadone, Psychodal, Risdal, Ion selective Electrode, Coated Wire , PVC Membrane, Flow Injection Analysis, Spectrophotometric Determination, charge Transfer Complex. |