Identification of tetracyclines by second-derivative ultraviolet spectrophotometry

Abstract

The second-derivative ultraviolet spectra of tetracycline, chlortetracycline, doxycycline, oxytetracycline and minocycline show a distinct appearance over their normal absorption curves. The characteristic peak amplitude ratios of the signals at 289 and 342 nm in the second-derivative spectra remain constant at different concentrations and even in mixtures, and are useful for identifying these individual antibiotics in pharmaceutical preparations.