Biotechnology is a fast growing industry in which products are produced using organisms such as bacteria, fungi, and hybridoma cells. The technology leverages DNA technology to transfect genes to produce specific mutant microorganisms that are engineered to produce biomolecules such as monoclonal antibodies, enzymes, and therapeutic polysaccharides. In the case of antibodies and enzymes, several favorable characteristics for pharmaceutical drugs have been achieved by their conjugation with biocompatible polymers such as polyethylene glycol (PEG). Proteins are commonly PEGylated to enhance in vivo stability and reduce immunogenic responses. PolyAnalytik has developed GPC methods that provide critical information on the efficiency of the PEGylation reaction, purity and stability of PEGylated proteins.