Methods for assaying function and/or activity and/or potency of isomerohydrolase proteins are provided.

The present disclosure is directed to methods of performing direct affinity-size exclusion chromatography, wherein there is a direct elution of the sample from the affinity chromatography column to the SEC column. The methods described herein allow for rapid and robust purification of target analytes from heterogeneous samples, and mitigate the need for complicated valve switching, buffer exchange, or other sample manipulation.