Thin-layer and column-chromatographic methods for simultaneous analysis of ambroxol hydrochloride and doxycycline hyclate in a binary mixture

Abstract

Two selective and reproducible methods have been established for simultaneous analysis of ambroxol hydrochloride (Amb) and doxycycline hyclate (Dox). The first method is densitometric TLC on silica gel with ethyl acetate-ethanol-glacial acetic acid-water 9:4:0.5:1 ( v/v ) as mobile phase. The linear range was 1–10 μg per zone (equivalent to 100–1000 μg mL −1 ) for both drugs. The second method is high-pressure liquid chromatography (HPLC) on a C 18 column with methanol-0.5 m phosphate buffer, pH 6.5 60:40 ( v/v ) as mobile phase and ultraviolet detection at 254 and 270 nm for Amb and Dox, respectively. This method was linear over the concentration ranges 37.5–750 and 50–750 μg mL −1 for Amb and Dox, respectively. The methods enabled specific and accurate analysis of these drugs in laboratory-prepared mixtures and in Ambrodoxy capsules. The results obtained agreed statistically with those obtained by use of the official B.P. methods.