Percent recovery computes the percentage of an original substance that is recovered after a chemical reaction is completed. Separation steps usually exploit differences in protein size physico-chemical properties binding affinity and biological activity. To add a bit to Dr.
In order to determine the enzyme yield you have to calculate total enzyme activity before loading on IEX call this A then calculate the total.
When dealing with an enzyme we often talk about specific activity. According to my biochemistry notes activity is 10 units of enzyme activity 10 mmol of substrate catalyzed to product under optimum conditions Then yield is defined as of total starting proteinenzyme in final purified protein fraction With this definition of yield it would make sense to say that you get 30 yield in the second step since you have 3000 mg 10000 mg of the original protein amount. It also determines their efficiency. Protein samples and standards are processed in the same manner by mixing them with assay reagent and using a spectrophotometer to measure the absorbances.