Standardisation Challenges in ELISA-Based Quantification of Equine Chorionic Gonadotropin (eCG/PMSG)

Commercial PMSG ELISA kits show non-comparable quantitative eCG/PMSG results, with measured concentrations consistently below nominal values for three kits and weak or narrow responses for others.

• Why it matters: Structural and glycosylation heterogeneity of eCG/PMSG makes antibody-based quantification hard to standardize, limiting reliable measurement for livestock synchronization and biomedical research.
• What they did: Six quantitative PMSG ELISA kits were grouped into three analytical profile sets; kit calibration standards were checked by Western blotting, Coomassie staining, and LC-MS/MS, and performance was tested using serial dilutions of two commercial PMSG preparations.
• The result: Calibration-material protein composition differed substantially, no eCG-derived peptides were detected by LC-MS/MS, and results were strongly influenced by calibration composition, assay format, and matrix effects—supporting the need for a commutable reference material and assay-specific validation.

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