Quantitative analysis of demeclocycline by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method suitable for the quality control of demeclocycline is described. The stationary phase is a poly(styrene-divinylbenzene) copolymer, kept at 60 degrees C. The mobile phase comprises 2-methyl-2-propanol-0.2 M potassium phosphate buffer (pH 9.0)-0.02 M tetrabutylammonium hydrogen sulphate (pH 9.0)-0.01 M sodium edetate (pH 9.0)-water (8:10:15:10:57, m/v/v/v/v). The flow rate is 1 ml min-1 and detection is performed at 254 nm. Official standards are compared and results for the analysis of a number of commercial bulk samples and preparations are presented. 4-Epidemeclocycline and demethyltetracycline are the main impurities. 4-Epidemethyltetracycline and 2-acetyl-2-decarboxamido-demeclocycline can also be present.