Modified Planar Sensors for Determination of Cefepime

Planar screen-printed potentiometric sensors sensitive to cefepime, a fourth-generation cephalosporine antibiotic, have been developed. Cefepime is an amphoteric antibiotic with the carboxyl and aminothiazole groups, which exists as a cation in strongly acidic media, a zwitterion in weakly acidic and neutral media, and an anion in alkaline media. The interval of pH 1.5–2.0 for obtaining the cationic electrode functions for the determination of cefepime has been established. The cefepime–tetraphenylborate associates have been used as electrode-active components; the optimum content of the latter for planar sensors is 2–3%. For the unmodified cefepime sensors, the electrode functions are linear in the range of 1 × 10^–5–1 × 10^–2 M, the angular coefficients are 50 ± 2 mV/pC, and the response time is 20 s. The role of the modifier, ZnO nanoparticles, in improving the electroanalytical properties of the sensors is shown. The introduction of a binary mixture of zinc oxide and cetylpyridinium chloride into carbon-based ink reduces the cefepime detection limit (1 × 10^–6 M) and increases the angular coefficient (58 ± 1 mV/pC), the interval of linearity of the electrode functions (1 × 10^–6–1 × 10^–2 M), and the sensor response time (17 s). A surfactant used as an electrode surface co-modifier stabilizes the nanoparticle dispersion. The use of the modified screen-printed sensors for the cefepime determination in medicinal and biological media, in particular, in saliva, is demonstrated.