Enter the specific rotation of a sample and the specific rotation of a pure enantiomer into the calculator to determine the optical purity.

## Optical Purity Formula

The following equation is used to calculate the Optical Purity.

OP = 100 * (SRS/SRPE)
• Where %OP is the percentage optical purity
• SRS is the specific rotation of the sample
• SRPE is the specific rotation of the pure enantiomer

To calculate the optical purity, divide the specific rotation of the sample by the specific rotation of the pure enantiomer, then multiply by 100.

## What is an Optical Purity?

Definition:

An optical purity is a measure of a substances ability to rotate the plane of polarization of a particle beam of light that has passed through it.

## How to Calculate Optical Purity?

Example Problem:

The following example outlines the steps and information needed to calculate Optical Purity.

First, determine the specific rotation of the sample. In this example, the specific rotation of the sample is measured to be 50.

Next, determine the specific rotation of the pure enantiomer. In this example the specific rotation of the enantiomer is 75.

Finally, calculate the optical purity using the formula above:

%OP = 100 * (SRS/SRPE)

%OP = 100 * (50/75)

%OP = 66.66%