ION-SELECTIVE ELECTRODE FOR RAPID DETERMINATION OF CEFTRIAXONE IN BIOLOGICAL OBJECTS

An ion-selective electrode for the rapid determination of ceftriaxone (Ceftr) in biological objects has been proposed, in which the ionic associate of octadecylamine (ODA) with Ceftr is an electrode-active component (EAC) of the Ceftriaxone-selective electrode (Ceftr-SE) membrane. In order to establish the mechanism of membrane function, the equilibria in the membrane-solution system were studied as a function of the acidity of the medium and the amount of EAC. At pH 6-9, the ionic associate (ODA) -Ceftr is stable and the membrane responds selectively to ceftriaxone. The optimal membrane composition for Ceftr-CE, (wt. %) was selected: (ODA) -Ceftr - 0.80, polyvinyl chloride - 33.06, ODA - 1.7 (100 mM), dioctyl sebacinate - 66.14, internal electrolyte Ceftr (0.01 M) + KCl (0.01 M). The electrochemical performance characteristics of the Ceftr-SE membrane were studied: linear range 1 × 10 -0.1 M, steepness of the electrode function 24.9 mV/decade, detection limit of Ceftr 8.3 × 10 M. The potentiometric selectivity coefficients of Ceftr-SE were determined by the method of bi-ionic potentials. The electrode was used for the determination of Ceftr in blood and saliva of covid patients. The correctness of the results of Ceftr determination was confirmed by the injected-found method.