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

By designing a novel flow-through electrolytic cell (FEC), bromine was prod uced near to the surface of the platinum electrode by electrochemical oxida tion of acidic KBr. The fast and weak chemiluminescence signal produced by the chen-deal reaction of the electrogenerated bromine with H2O2 was greatl y enhanced by tetracyclines Based on these observations, a new, sensitive a nd simple electrogenerated chemiluminescence (ECL) method for the determina tion of tetracyclines was developed. Under the optimum experimental conditi ons, the calibration graphs are linear over the range 3.0 x 10(-8) to 5.0 x 10(-5) g ml(-1) for tetracycline, 2.0 x 10(-7) to 2.4 x 10(-5) g ml(-1) fo r oxytetracycline and 1.0 x 10(-7) to 5.0 x 10(-5) g ml(-1) for chlortetrac ycline. The limits of detection (S/N = 3) are 1.0 x 10(-8) g ml(-1) for tet racycline, 7.0 x 10(-8) g ml(-1) for oxytetracycline and 1.5 x 10(-7) g ml( -1) for chlortetracycline. For the determination 5.0 x 10(-7) g ml(-1) tetr acycline, the relative standard deviation was <5%. The proposed method was used to determine tetracyclines in pharmaceutical formulations. (C) 2001 El sevier Science B.V. All rights reserved.