Flow injection analysis of chloramphenicol by using a disposable wall-jet ring disk carbon electrode

A preanodized screen-printed ring disk carbon electrode was applied to the determination of chloramphenicol (Ph-NO2, CAP) by flow injection analysis (FIA). By setting up the first irreversible reduction reaction of Ph-NO2 to Pb-NHOH at the disk electrode, the following reversible oxidation of hydroxylamine (Ph-NHOH) to the nitroso (Ph-NO) derivative can be monitored/collected at the ring electrode for CAP analysis. The interference from dissolved oxygen and others can thus be avoided by using this approach and precise CAP determination can be easily performed by FIA under aerobic conditions. Preanodization treatment helps to lower the overpotential of the electrochemical reaction of CAP and favors the selective detection in aqueous medium. Under the optimum conditions, ten repetitive determinations at I mu M and 10 mu M CAP resulted in relative standard deviations of less than 4%, indicating good reproducibility of the system. A linear calibration range of 0.1 - 20 mu M with a detection limit of 0.074 mu M (S/N= 3) was obtained. Veterinary pharmaceutics were finally analyzed by this sensor to validate its practical applicability.