Ion-selective electrodes for determining cephazolin in biological media

An ion-selective electrode with plasticized polyvinylchloride membrane that is based on a cephazolin--tetradecylammonium ionic associate has been developed. The ratio of components and the solubility product of the ionic associates [(2.2 ± 0.1) x 10⁻ ⁸] were determined. The compound is thermally stable up to 70°C. The EMF is linearly dependent on the cephazolin concentration in the range from 1 x 10 - 5 to 1 x 10⁻ ¹ M. The slope of the electrode function is 56 ± 2 mV/pC. The selectivity to inorganic ions allows the proposed system to be used for cephazolin determination in biological media. In particular, a method for rapid determination of cephazolin in complex saliva is developed.