Examples may include a method of making a protein-PEG conjugate salt with increased hydrophobicity. The method may include providing an aqueous protein solution. This aqueous protein solution may include a protein and a pH buffer. The method may also include reacting a polyethylene glycol with the protein to form a protein-PEG conjugate. The method may further include protonating an amino group on the protein-PEG conjugate with a hydrophobic organic acid in an organic phase. The protonation may form the protein-PEG conjugate salt having a hydrophobic anion that increases the hydrophobicity-PEG conjugate salt.
