Flow-injection chemiluminescence determination of tetracyclines with in situ electrogenerated bromine as the oxidant

Abstract

By designing a novel flow-through electrolytic cell (FEC), bromine was produced near to the surface of the platinum electrode by electrochemical oxidation of acidic KBr. The fast and weak chemiluminescence signal produced by the chemical reaction of the electrogenerated bromine with H 2O 2 was greatly enhanced by tetracyclines Based on these observations, a new, sensitive and simple electrogenerated chemiluminescence (ECL) method for the determination of tetracyclines was developed. Under the optimum experimental conditions, the calibration graphs are linear over the range 3.0×10 −8 to 5.0×10 −5 g ml −1 for tetracycline, 2.0×10 −7 to 2.4×10 −5 g ml −1 for oxytetracycline and 1.0×10 −7 to 5.0×10 −5 g ml −1 for chlortetracycline. The limits of detection ( S/ N=3) are 1.0×10 −8 g ml −1 for tetracycline, 7.0×10 −8 g ml −1 for oxytetracycline and 1.5×10 −7 g ml −1 for chlortetracycline. For the determination 5.0×10 −7 g ml −1 tetracycline, the relative standard deviation was <5%. The proposed method was used to determine tetracyclines in pharmaceutical formulations.