1996 Volume 37 Issue 4 Pages 222-225_1
A biological method for residual tetracyclines (TCs) in propolis was evaluated. Oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) were extracted from a sample with 5% citric acid containing 0.001M EDTA-2Na. The extract was washed with hexane and diethyl ether, followed by a Sep-pak Plus PS2 cartridge clean-up and TCs adsorbed in the cartridge were eluted with methanol. The eluate was concentrated to dryness, and the residue was redissolved in a phosphate buffer (pH 4.5) and treated with polyamide resin to remove antibacterial substances originating from propolis. The cup-plate method was employed for quantitative determination, and microbioautography for identification of TCs. The recoveries were 97.6% (OTC), 92.7% (TC) and 86.3% (CTC), and the detection limits were 0.1μg/g (OTC, TC) and 0.02μg/g (CTC).
