Abstract
A mixture of sulphametrole (SM) and trimethoprim (TMP) in laboratory-made mixtures and in tablets dosage form (Lidaprim(R)) has been adequately quantitated by first-derivative spectrometry which has been found superior to Vierordt's method since the latter is incapable of overcoming the severe spectral overlapping of SM and TMP. Linear relation between D1 (i.e. dA/d-lambda) and concentrations of the two drugs was demonstrated in the range 5 to 30 and 2 to 12-mu-g ml-1 for SM and TMP, respectively. Recovery experiments indicated satisfactory accuracy of the first-derivative method.