Analytics are required at each stage of the purification process of a biopharmaceutical to determine the efficiency of the purification step. For example, a purification step designed to remove aggregates will be monitored using size exclusion chromatography (SEC) to quantify the efficiency of aggregate removal and to ensure that the required purity has been achieved before moving on to the next step. Whichever LC technique is employed, it must be robust. Where product purity is compromised then fractionation and characterisation can be instigated to determine corrective action and reduce the risk of losing valuable product.