The development and validation of the new analytical method by ultra-high-resolution liquid chromatography of sulfamethoxazole and trimethoprim in suspension was carried out in a national laboratory, carried out with the parameters specified in the current pharmacopoeia, such as instrumental precision, specificity, linearity of the system. , method linearity, accuracy and reproducibility. The resulting values for instrumental precision were RSD 0.32% and 0.35%, the specificity without interference for the analytes, system linearity with correlation coefficients of 0.9998 and 0.9999, coefficient of determination of 0.9995 and 0.9997, method linearity with correlation coefficients of 0.9991 and 0.9992, coefficient of determination of 0.9982 and 0.9984, accuracy with recovery values of 100.81% and 99.34%, precision with repeatability of 102.02% and 97.63% and with reproducibility 100.73 and...