The present invention provides processes for the manufacturing of polypeptide conjugates. In particular, the invention provides methods for the purification of polypeptide conjugates, which include at least one polymeric modifying groups, such as a poly(alkylene oxide) moiety. Exemplary poly(alkylene oxide) moieties include poly(ethylene glycol) (PEG) and poly(propylene glycol). In an exemplary process, hydrophobic interaction chromatography (HIC) is used to resolve different glycoforms of glycoPEGylated polypeptides.