About 15 g of a protein mixture is flowing through a column at a velocity of 30 cm/hr., the peak in concentration exists the column in 90 min and the standard deviation of this peak is given as 10 min.

(a) How long must we purify for a 95% yield?

(b) If we increase the flow to 50 cm/hr., how long must we run for this same yield if the process is controlled by diffusion through the packing?

(c) How long must we wait if the process is controlled by mass transfer?

(d) How long must we wait if the column actually contains equilibrium stages?