Question

Aqueous two-phase extraction is used to recover \(\alpha\)-amylase from a solution. A polypropylene glycol–dextran mixture is added and the solution separates into upper and lower phases. The partition coefficient is 4.0 and the ratio of upper to lower phase volume is 5.0. The enzyme recovery or yield (in percentage, rounded off to the nearest integer) is ____________________.

Hint:

For two-phase extraction: \(Y=\dfrac{K\,V_U}{K\,V_U+V_L}\). A large \(K\) and larger \(V_U\) both increase recovery in the upper phase.

Answer 1

Correct Answer: 94

Step 1: For partitioning into an upper (U) and lower (L) phase with partition coefficient \(K=\dfrac{C_U}{C_L}\) and volumes \(V_U, V_L\), the fraction recovered in the upper phase is \[ Y=\frac{K V_U}{K V_U+V_L}. \] Step 2: Given \(K=4\) and \(V_U/V_L=5\Rightarrow V_U=5V_L\). Then \[ Y=\frac{4\cdot 5V_L}{4\cdot 5V_L+V_L}=\frac{20}{21}=0.95238. \] Step 3: Percentage recovery \(=95.238%\approx \boxed{95%}.