Studies on spectrophotometric determination of tetracycline and its degradation products

The spectrophotometric method was employed for determination of tetracycline (1) and its degradation products epitetracycline (2), anhydrotetracycline (3) and anhydroepitetracycline (4). The determination has been based on the difference in the molar absorptivities (epsilon) of 1 and 2 at 254 and 267 nm, as well as of 3 and 4 at 260 and 272 nm, respectively. The difference in epsilon at 357 and 390 nm has also been employed for the determination of 1 and 3. On the basis of these dependences, the compounds were determined both in synthetic mixtures and in some solid dosage forms.