title: Voltammetry and quantification of the contraceptive drug norethisterone in bulk form and pharmaceutical formulation.
abstract: The electrochemical behavior of norethisterone at the mercury electrode was studied in the universal buffer of various pH values using dc-polarography, cyclic voltammetry and controlled-potential electrolysis. Norethisterone was reduced at the mercury electrode via the consumption of two electrons corresponding to reduction of the 3-keto-delta-4-group in the A-ring of the molecule. The pK(a) value (8.7) of norethisterone was determined from the polarographic and spectrophotometric measurements. A fully validated, simple, sensitive, precise and inexpensive square-wave adsorptive cathodic stripping (SWAdCS) voltammetry procedure was described for trace quantification of bulk norethisterone. The stripping voltammetry peak current of norethisterone in a universal buffer of pH 5 following its accumulation onto the hanging mercury drop electrode (HMDE) at -0.6 V (versus Ag/AgCl/KCl(s)) for 130 s showed a linear response with the concentration over the range 5 x 10(-9) to 3 x 10(-7)M norethisterone. Detection and quantitation limits of 1.5 x 10(-9) and 5 x 10(-9)M bulk norethisterone, respectively, were achieved. The proposed procedure was successfully applied for the assay of norethisterone in Steronate tablets without interference from excipients.
authors.affiliation: Chemistry Department, Faculty of Science, Tanta University, 31527 Tanta, Egypt. mmghoneim@usa.net
authors.forename: M M
authors.initials: MM
authors.lastname: Ghoneim
authors.forename: A M
authors.initials: AM
authors.lastname: Abushoffa
authors.forename: Y I
authors.initials: YI
authors.lastname: Moharram
authors.forename: H S
authors.initials: HS
authors.lastname: El-Desoky
mesh_terms: D002021:Buffers; D002138:Calibration; D002626:Chemistry, Pharmaceutical; D003280:Contraceptives, Oral, Synthetic / Q000032:analysis* / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D008628:Mercury; D008956:Models, Chemical; D015394:Molecular Structure; D009640:Norethindrone / Q000032:analysis* / Q000737:chemistry; D004364:Pharmaceutical Preparations / Q000737:chemistry; D011048:Polarography / Q000379:methods; D015203:Reproducibility of Results; D013607:Tablets; D013678:Technology, Pharmaceutical / Q000295:instrumentation / Q000379:methods* / Q000592:standards
chemical_list: D002021:Buffers; D003280:Contraceptives, Oral, Synthetic; D004364:Pharmaceutical Preparations; D013607:Tablets; D008628:Mercury; D009640:Norethindrone