Simultaneous determination of trimethoprim and sulphamethoxazole in buffalo meat using liquid chromatography

Trimethoprim and sulphamethoxazole combinations have been used extensively as for treatment of bovine infections. Residues of these antimicrobial agents are harmful to the consumer's health and could induce resistance in pathogenic microbes. A liquid chromatographic method for simultaneous trace determination of trimethoprim and sulphamethoxazole in buffalo meat matrix was established for the quantification purpose. The analytes were co-extracted using liquid-liquid extraction approach. The chromatographic separation was performed using a C18 column with a mobile phase comprised of ammonium phosphate buffer and acetonitrile (85: 15, v/v) in an isocratic elution mode. The determination is carried out by liquid chromatography using PDA detector at a wavelength of 270 nm. Linearity, limits of detection (LOD) and quantification (LOQ), recovery, precision, and selectivity and recoveries were determined. The assay was linear in the concentrations ranging from 25 to 200 μg/kg. Relative standard deviations of the recoveries were less than 5% within the same day and less than 10% between days. The LOQ for trimethoprim and sulfamethoxazole were 42 and 68 μg/Kg, respectively. This RP-HPLC method has highly applicability for routine analysis of residual trimethoprim and sulphamethoxazole in buffalo meat below established MRL.