So yeah it’s tough – these are all research chemical sites (After doing more research, I’d actually recommend using this one: https://www.targetmol.com/compound/Verteporfin – it was used by someone else in another group I am). Ideally, we’d get either brand name visudyne from Bausch or Verteporfin from a compounding pharmacy. But otherwise, these sites are usually pretty good when their purity is high.