Table 5.

Methods of identifying glycans and their applications.

Application	Example
Bioanalytical and bioinformatics	Data integration at different structural levels to identify various glycoforms of recombinant human chorionic gonadotropin (r-hCG), urinary hCG (u-hCG), and recombinant follicle stimulating hormone (r-hFSH) revealed that these biopharmaceuticals differ considerably in their glycosylation patterns [156].
Resolution discrepancies	Between high-resolution native and glycopeptide-centric mass spectrometric approaches for the glycosylation of erythropoietin variants [157].
Glycan microheterogeneity	To identify multiple glycosylation sites in the vascular endothelial growth factor IgG (VEGFR-IgG) fusion protein to understand the functional significance of each glycosylation pattern [158].
Glycoforms	Several glycoforms using hybrid high-performance liquid chromatography–MS approaches [159], such as 24 glycoengineered erythropoietin variants with varying glycan branching and sialylation levels, are crucial parameters for biotherapeutic efficacy.
NMR	Identification of glucose-induced glycation in mAbs and other proteins using NMR spectroscopy. [160].
Novel glycoforms	Identification of novel glycosylations in human-serum-derived factor IX. [161].
Mass spectral profiling	The N-linked, O-linked, ganglioside, and glycosaminoglycan compound classes and the tandem mass spectrometry of glycans have led to spectral glycoproteomics [162].
N-glycosylation profile	Analysis of trastuzumab biosimilar candidates using normal-phase liquid chromatography and matrix-assisted laser desorption/ionization time-of-flight MS [163].
Microheterogeneity	Composite glycosylation profiles and other microheterogeneities in intact mAbs via high-resolution native MS using a modified Orbitrap [164].
Targeted site-specific quantitation	N-and O-glycopeptides using 18O-labeling and product ion-based MS [165].
Hybrid MS	Approaches in glycoprotein analysis and their usage in scoring biosimilarity [166].