I= ELECTROCHEMICAL STUDIES OF SOME BIOLOGICALLY ACTIVE COMPOUNDS USING GRAPHITE PASTE ELECTRODE
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Title of Thesis
ELECTROCHEMICAL STUDIES OF SOME BIOLOGICALLY ACTIVE COMPOUNDS USING GRAPHITE PASTE ELECTRODE

Author(s)
Syed Azhar Ali
Institute/University/Department Details
University of Karachi, Pakistan./Department of Chemistry
Session
1995
Subject
Chemistry
Number of Pages
329
Keywords (Extracted from title, table of contents and abstract of thesis)
graphite paste electrode, a-methylodopa, bendrofluazide, furosemide, hydrochlorothiazide, reserpine, cyclic voltammetry, antihypertensive compounds

Abstract
Electrochemical study of some biologically active compounds (a-methylodopa, bendrofluazide, furosemide, hydrochlorothiazide, and reserpine) has been done at a carbon paste electrode vs. Ag/AgCI reference electrode in various supporting electrolytes. Cyclic voltammetry was performed to determine qualitative and quantitative characteristics of these compounds. The compound a-methyldopa showed a quasi-reversible electron transfer reaction. The values of transfer coefficient a or B were determined. In a very few systems, the value of Ko the standard heterogeneous rate constant were obrained form Ep vs. values. The larger values of Ep were obtained due to the use of unmodified carbon paste electrode which decreases the rate of electron transfer at the surface of the test electrode. Other compounds like bendrofluazide, furosemide, hydrochlorothiazde, and reserpine showed a totally irreversible electron transfer at the unmodified carbon paste electrode. The values of transfer coefficients, B were determined by using different equations. The quantitative studies with cyclic voltammetry revealed that the use of a carbon paste electrode can be used to quantify these compounds (a-methyldopa 4.2X10-3 to 8.4X10-6 M, bendrofluazide 2.37X10-5 to 4.28X10-6 M, furosemidel 2X10-5 to 2.42X10-4 M hydrochlorothiazide 3.0X10-4 to 1.0X10-5M, and reserpine 1.41X10-5 to 2.54X10-6 M). This method can be applied in the pharmaceutical quality control assays of these compounds which has not been reported earlier.

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
56.56 KB
2 1 Introduction 1
283.82 KB
  1.1 Voltammetry and polarography 1
  1.2 Kind of voltammetry 2
  1.3 Cyclic voltammetry 3
  1.4 Explanation of cyclic voltammogram 3
  1.5 The shape of a current-potentia curve 5
  1.6 Cyclic voltammetry the mathematical approach 6
  1.7 Carbon paste electrode 24
  1.8 Early voltammetric and polarographic work on antihypertensive compounds 26
  1.9 Pharmacology of antihypertensive drugs 30
  1.10 Hypertension 30
  1.11 Pharmacological aspects 32
  1.12 Aims of the present work 33
3 2 Experimental 34
923.2 KB
  2.1 Chemicals 34
  2.2 Apparatus 36
  2.3 Stock solutions 39
  2.4 Standardization of stock solutions of acids 40
  2.5 Preparation of stock solutions of bases 40
  2.6 Preparation of stock solutions of biologically active compounds 41
  2.8 Packing of carbon paste electrode 42
  2.9 General procedure to take cyclic voltammogram at CV-IB system 44
  2.10 Determination of base-line 47
  2.11 Determination of cyclic voltammogram of analyte 48
  2.12 Base-line 50
4 3 Results and Discussion 119
2068.56 KB
  3.1 the qualitative characteristics of the cyclic voatammograms of a-methyldopa 119
  3.2 Bendrofluazide 206
  3.3 furosemide 234
  3.4 Hydrochlorothiazide 254
  3.5 Reserpine 302
5 4 References 322
89.32 KB