SEPARATION OF TETRACYCLINE AND ITS DEGRADATION PRODUCTS BY CAPILLARY ZONE ELECTROPHORESIS

The capillary zone electrophoresis of tetracycline and its degradation products is described. Various substances. including surfactants and metal ions, were employed as additives in the running electrolyte to improve the resolution. Using disodium ethylenediaminetetraacetate as an additive in phosphate buffer solution, tetracycline and its degradation products were completely separated from each other. The baseline separation obtained completely meets the needs for determining the contents of tetracycline, 4-epitetracycline, anhydrotetracycline (ATC) and 4-epianhydrotetracycline (EATC) in tetracycline samples. Further, two unknown substances co-existing with ATC and EATC were separated that had not been mentioned or separated before. Further investigations using other techniques are needed to determine the structures of these two unknown substances. The pH dependence of the migration behaviour of tetracycline and its degradation products was also explored. The migration behaviour of zwitterionic substances is so dependent on the pH of the buffer than the elution order may be changed with change in pH. The pH dependence of electroosmotic flow over the pH range 4-11 was also determined.