We want to use a four-stage countercurrent extractor to separate two growth hormones present as part of an aqueous protein concentrate. The activity of each hormone in the feed solution is a nominal value of 1. We add phosphates to this concentrate, and extract with a polyethylene glycol solution which forms a second immiscible aqueous phase. The hormones partition between these phases with values of K equal to 6.0 and 8.0, respectively, where

K = [activity in polyethylene glycol solution] / [activity in phosphate solution]

We want to investigate the recovery and product purity possible with this extraction.

(b) In a second series of experiments, we feed the 50 kg/hr concentrate between the second and third stages, and feed an additional 50 kg/hr of protein-free phosphate solution into the first stage. The polyethylene glycol flow is unchanged. How are the percent recovery and the purity altered?