Ion-selective electrodes for the determination of antihistaminic drug ketotifen

The ion-selective poly(vinyl chloride) membrane electrodes sensitive for ke totifen are described. The preparation of electrodes is based on the format ion of ion-pair ketotifen-[3,5-bis(trifluoromethyl)phenyl] berate with foll owing solvents: 2-nitrophenyl octyl ether (electrode A), 2-nitrophenyl dode cyl ether (electrode B), bis(2-ethylhexyl)sebacate (electrode C) or 1-isopr opyl-4-nitrobenzene (electrode D). The electrodes were found to respond to ketotifen with sub-Nernstian slopes, depending on the properties of the sol vent mediators. The electrodes could be used for the determination of ketot ifen in bulk substance or pharmaceutical. forms with a reasonable precision and accuracy.