Chemiluminescence determination of tetracyclines using a tris(2,2′-bipyridine)ruthenium(II) and potassium permanganate system

A chemiluminescence method for the determination of tetracyclines was developed. The method is based on an enhancement of tetracyclines upon the chemiluminescence light emission of tris(2,2'-bipyridine)ruthenium(II). In a sulfuric acid medium, chemiluminescence light emission is generated upon continuous oxidation of tris(2,2'-bipyridine)ruthenium(II) by potassium permanganate, catalyzed by Mn(II). The light-emission intensity is enhanced when the tetracyclines are also present in the reaction system. Under the optimum conditions, the calibration curves are linear over the range 1.0x10(-7)-1.0x10(-5) g/ml for tetracycline, 4.0x10(-8)-1.0x10(-5) g/ml for chlortetracycline and 1.0x10(-7)-1.0x10(-5) g/ml for oxytetracycline. The limits of detection (S/N=S) are 2.0x10(-8) g/ml for tetracycline, 1.0x10(-8) g/ml for chlortetracycline and 2.0x10(-8) g/ml for oxytetracycline. The proposed method was used to determine tetracyclines in pharmaceutical formulations with good results.