Determination of related substances in disulfide-rich peptide ziconotide by establishing tandem mass spectrometry methods.

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Identification and determination of structurally related peptide impurities in thymalfasin by liquid chromatography-high-resolution mass spectrometry.

Thymalfasin is an important peptide drug widely used for the single or combination treatment of hepatitis, sepsis, cancer, and immunodeficiency. Accurate purity assessment of thymalfasin material is essential for thymalfasin certified reference materials (CRMs) production and analytical method validation, in which comprehensive determination of thymalfasin-related impurities is required to avoid quantitative bias. In this study, liquid chromatography-high-resolution mass spectrometry (LC-hrMS) methods have been established to comprehensively characterize and quantify thymalfasin-related impurities using a thymalfasin China Pharmacopoeia (ChP) standard and then successfully applied to three commercial thymalfasin materials.