The formulation comprisesof Ampho-Moronal®-Suspension (Dermapharm) and a buffered, preservated aqueous solution of colistinsulfate and tobramycin sulfate. Two simple, well established high-performance liquid chromatography(HPLC) methods in the European Pharmacopoeia (EP) for impurity profiling of the two active ingredientsamphotericin B and colistin sulfate were combined with a newly developed sample extraction proce-dure for the suspension.