Application of Absorbance Ratios to Analysis of Pharmaceuticals V: Analysis of Tetracycline Hydrochloride in Presence of Anhydrotetracycline and Epianhydrotetracycline

Use of Circular Dichroism in Analysis of Mixtures of Tetracycline and 4-Epitetracycline and its Application to Assay of Commercial Products

“…Results of the present study indicate small amounts of anhydrotetracyclines and from 3 to 1 7 z epitetracycline. There is no reason to expect that the samples used previously (9) were the same as those used in the present study, nor is it reasonable to expect large errors in epitetracycline content in the present method even in the presence of 5 anhydrotetracycline.…”

“…(9) reported that the maximum amount of anhydrotetracycline present in six commercial samples tested by them was 10%; in the present study the maximum percentage of anhydrotetracyclines in eight samples was 5.3 %.I The theoretical ellipticity that would be observed at 262 nm. would be -0.0513", and the absorbance of the solution at 356 nm.…”

“…When Pernarowski et al (9) examined six commercial tetracycline products, using absorbance ratios at 357 and 391 nm.. they reported the samples as having %94% of the labeled tetracycline content, the remainder being only anhydro compounds as seen by TLC. Results of the present study indicate small amounts of anhydrotetracyclines and from 3 to 1 7 z epitetracycline.…”

“…range, the absorbance ratio technique by itself is not useful for samples containing these decomposition products. Pernarowski et al (9) used an absorbance ratio at 357 and 391 nm. to detect tetracycline in the presence of anhydrotetracycline and epianhydrotetracycline.…”

Tetracycline Degradation Products in Commercially Available Tetracycline-7-3H

“…was used with the following equation (9) to calculate the percentage of 1 present in the solution: For chromatography. 50 GI.…”