Residual keratan sulfate in chondroitin sulfate formulations for oral administration

► Chondroitin sulfate formulations from shark origin are largely contaminated. ► Keratan sulfate comprises around 16% of these biomedical preparations. ► The pharmacopeiaś method (electrophoresis) does not detect such contaminant. ► SAX-HPLC is proved to be a more reliable method. ► These findings forewarn manufacturers and audits for better products.