simulataneous analysis of trimethoprim and sulphamethoxazole drug combinations in dosage forms by high performance liquid chromatography

a sensitive high performance liquid chromathography (hplc) analytical procedure was developed for the quantitive determination of trimethoprim (tm* and sulphamethoxazole (sm) in commercial dosage forms. c18 analytical column (stainless steel, 25 cm * 4.6 mm i.d.) was packed with 5-*m particles of the reversed phase material and used for assays. mobile phase containing 0.025 m sodium phosphate as aqueous phase and acetonitrile with 0.4% triethylamine as organic phase. the drugs were quantified at flow-rate of 1.2 ml/min, with ultraviolet detection at 260 nm. the minimum detectable quantities in assays were 100 ng/ml for sm and 75 ng/ml for tm. the method is well suited to routine application and adequate sensitivity with precision.