Modified planar sensors for determination of some cephalosporin antibiotics in biological and medicinal media

Abstract

Pluripotential cephalosporin antibiotics of different generations active against Gram-negative bacteria are used when treating urinary tract infections, mild and moderate pyelonephritis, acute otitis in children, etc. Rapid determination of cephalosporin antibiotics in the biological fluids is important to evaluate physiological and biochemical processes resulting from their metabolism in a human organism. Planar potentiometric sensors of different types — unmodified and modified with polyaniline (0.3 – 1%), NiZnFeO nanoparticles, and their binary mixes — are developed on the basis of associates of tetradecylammonium (TDA) with complex compounds silver (I) — β -lactam [Ag (I) – ( β -lac) 2 ] which are sensitive to some cephalosporin antibiotics, i.e., cefazoline (Cef), cefuroksime (Cefur) and ceftriaksone (Ceftr). In the sensors of type I, electrode-active components (EAC) and modifiers were added to carbon-containing ink, whereas in type II sensors the polyvinylchloride plasticized unmodified and modified membranes based on [Ag 2 (Ceftr) 2 ] 2 · 2TDA were used. Electroanalytic and operational characteristics of unmodified and modified planar sensors in aqueous solutions of cefazoline, cefuroxime, ceftriaxone and against the background of oral fluid were estimated. It is shown that introduction of the modifiers into sensor membranes leads to stabilization of their potential, increases angular coefficients of electrode functions, decreases the antibiotic detection limit to 1.7 Ч 10 –5 M, reduces the response time and potential drift. Nanoparticles of NiZnFeO appeared to be the most effective modifier. For the sensors of type II linearity of electrode functions is observed in the range of ceftriaxone concentrations of 3.1 Ч 10 –5 – 0.1 Ч 10 –1 M. Depending on the content of the electrode active components in the membrane phase of the unmodified planar sensors, the values of the angular coefficients of the electrode functions vary within 25 – 27 mV/p C and correspond to the values of the non-static value for doubly-charged ions. The linearity intervals of sensor electrode functions are identical at all EAC concentrations under study; as Ceas increases, potential drift and response time decreases. The developed planar sensors were used for determination of cephalosporin antibiotics in model aqueous solutions, medicinal preparations and oral fluid.