Simultaneous determination of sulfamethoxypyridazine, sulfamethoxazole, sulfadimethoxine and their associated compounds by liquid chromatography

A liquid chromatography method is described to determine sulfamethoxypyrida zine (SNIP), sulfamethoxazole (SMX), sulfadimethoxine (SDM), trimethoprim ( TMP) and bromhexine (BRO) by using a Kromasil C-18 column and 10 mm citrate buffer (pH 3.0)-methanol (from 31:69 to 69:31) as mobile phase in gradient mode. The mobile phase flow-rate and sample volume injected were 1 ml/min and 20 mul, respectively. The selected wavelength for the determination was 255 nm . The limits of quantification go from 200 mug/l for SDM to 1100 mug/l for BRO and the run time was 13 min. The method was applied in veterinary commercial formulations. Analytical re sults proved that some commercial claimed levels were not in agreement with the obtained results, as they were in other cases. (C) 2001 Published by E lsevier Science B.V. All rights reserved.