The stock solution of tetracycline (1000 lg mL1) was prepared by dissolving the appropriate amount of its hydrochloride salt (Sigma–Aldrich, Germany) in 5.0 M hydrochloric acid (HCl, Labscan, Thailand).
The stocksolution of tetracycline (1000 lg mL1) was prepared by dissolvingthe appropriate amount of its hydrochloride salt (Sigma–Aldrich,Germany) in 5.0 M hydrochloric acid (HCl, Labscan, Thailand).