The formula to calculate the Optical Purity (%OP) is:
\[ \%OP = 100 \times \left( \frac{SRS}{SRPE} \right) \]
Where:
Let's say the Specific Rotation of the Sample (SRS) is 25 and the Specific Rotation of the Pure Enantiomer (SRPE) is 50. Using the formula:
\[ \%OP = 100 \times \left( \frac{25}{50} \right) \]
We get:
\[ \%OP = 50\% \]
So, the Optical Purity is 50%.