[Determination of tetracyclines antibiotics by reversed-phase high performance liquid chromatography]

A method for the determination of 7 tetracycline antibiotics (TCs) by reversed-phase high performance liquid chromatography is described. TCs were successfully separated on a Diamonsil C18 column (250 mm x 4.6 mm i.d., 5 microns) using methanol-acetonitrile-0.01 mol/L oxalic acid (pH 2.0) (11:22:67, volume ratio) as mobile phase at a flow rate of 0.8 mL/min and detected at 267 nm within 22 min. Effects of the pH value of the mobile phase, concentration of the mobile phase buffer, elution composition and detection wavelength on the response and retention were studied. Tetracycline (TC) and oxytetracycline(OTC) in medicinal tablets were quantitated by standard added method. It has been proven that the method is fast, accurate and suitable for routine analysis.