High performance liquid chromatographic analyses of sulphonamides and dihydrofolate reductase inhibitors .1. Separations in methanol-modified solutions

Twenty-two sulphonamides and the three commonly used dihydrofolate reductase inhibitors have been subjected to an investigation of retention behaviour on a silica based reversed phase. Effects of variation in the percentage of methanol and the pH have been determined isocratically and the methanol gradients developed have been modified by variations in the concentration of the phosphate buffer. Significant variations in retention behaviour were observed such that the majority of combinations of drugs could be screened for. No set of conditions studied gave rise to a total separation of all drugs, but around twenty drugs were commonly resolved.