text: Consider a distillation column with a feed of say propane and pentane. You would have a distillate vapour and a liquid bottoms. It would reasonable to assume that vapour distillate would be rich in propane.\n\n%Recovery =100% x [(amt. of propane in vapour distillate)/(amt. of propane in the feed to the distillation column)]\n\nHope this answers it.