title: New polyvinyl chloride membrane electrode without inner reference solution for the determination of methadone.
abstract: A PVC membrane electrode, without inner reference solution, based on an ion association extraction system responding to methadone (MD) is described. It incorporates a methadone-tetrakis(4-chlorophenyl)borate ion-pair complex in 2-nitrophenyloctyl ether. The prepared electrode exhibits a near Nernstian response (59.5 mV per decade) over the concentration range 2.5 x 10(-5)-10(-1) M MD in solutions of pH 2.0-9.0. The reproducibility of the electrode potentials was +/-1 mV by day during at least 6 months. Response time was about 5 s for MD concentrations between 10(-5) and 10(-1) M. Determinations of MD in pharmaceutical preparations (tablets and syrups) by direct potentiometry gave an average recovery of 99.3% (w/w) and a mean S.D. of 1.5% (w/w).
authors.affiliation: Department of Chemistry, Faculty of Science, Cairo University, Fayoum Branch, 63514 Fayoum, Egypt. s_khalil_99@yahoo.co.uk
authors.forename: Sabry
authors.initials: S
authors.lastname: Khalil
authors.forename: Ahmed
authors.initials: A
authors.lastname: Kelzieh
mesh_terms: D002138:Calibration; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D008567:Membranes, Artificial; D008691:Methadone / Q000032:analysis*; D009294:Narcotics / Q000032:analysis*; D019999:Pharmaceutical Solutions; D011143:Polyvinyl Chloride; D011199:Potentiometry; D015203:Reproducibility of Results; D012996:Solutions; D013607:Tablets
chemical_list: D007202:Indicators and Reagents; D008567:Membranes, Artificial; D009294:Narcotics; D019999:Pharmaceutical Solutions; D012996:Solutions; D013607:Tablets; D011143:Polyvinyl Chloride; D008691:Methadone