Srikanth Voruganti: Not an "assay", an HPLC method of analysis. What will the compound be dissolved in (the matrix)? *You should be able to use a wide-pore, C18 column with UV detection to develop an initial HPLC method. After properly dissolving a standard, run a scouting gradient in full scan mode (UV/VIS ~ 210 to 380nm) to optimize settings. The real issue will be dealing with exactly what the thiostrpton is in. The proposed method will need to be developed to be selective for the compound while not allowing any of the interfering compounds to co-elute, invalidating the method. Some sample prep may be needed. Developing a method for a pure compound is easy. A mixture, esp if any unknowns are present is far more complex. Make sure you work with a professional chromatographer (and not on your own) to achieve success.