Compositions and methods are provided for efficiently preparing a completely deglycosylated antibody where efficiency is measured in relative amounts of reagents in soluble or lyophilized form, and time and temperature of the reaction. Compositions and methods are also provided for separating substantially all N-linked glycans from a glycosylated antibody and for preserving functionality of the antibody. The methods are compatible with glycan labeling and protease digestion without the need for prior purification steps.

Provided herein are methods for assessing cell surface glycans, e.g., N-glycans, by assessing a sample of released surface glycans, and determining the presence, absence, or level of glycans present in the sample. Also provided are methods of assaying and/or evaluating a cell composition by assessing the cell surface glycan profile of the cell composition and comparing the profile to a reference sample. Methods for manufacturing and/or culturing a plurality of cell compositions having consistent surface glycan expression with low variability are also provided.

Provided herein are methods for assessing cell surface glycans, e.g., N-glycans, by assessing a sample of released surface glycans, and determining the presence, absence, or level of glycans present in the sample. Also provided are methods of assaying and/or evaluating a cell composition by assessing the cell surface glycan profile of the cell composition and comparing the profile to a reference sample. Methods for manufacturing and/or culturing a plurality of cell compositions having consistent surface glycan expression with low variability are also provided.

Systems and methods for characterizing low molecular weight (LMW) protein drug product impurities are provided. One embodiment uses hydrophilic interaction chromatography (HILIC) coupled to mass spectrometry analysis. After removal of the N-linked glycans from the protein drug product, for example an antibody drug product, the elution of LMW impurities from the HILIC column was determined by the size of the molecular weight species. In some embodiments, the HILIC separation is performed under denaturing conditions, making the detection of LMW forms using this method highly comparable to both SDS-PAGE and CE-SDS methods. LMW drug product impurities include, but are not limited to light chain, half antibody, H2L, H2, HL, HC, peptide backbone-truncated species, and combinations thereof.