Isoelectric focusing sample matrix

Abstract

The present disclosure provides icIEF sample matrices that enable icIEF analysis of PEGylated proteins in their real conjugated states. The sample matrices of the present disclosure can include glycine, which enables the separation of co-migrated PEGylated protein charge variants. The sample matrices can also include taurine, which further improves icIEF assay by depleting matrix induced baseline interferences. Accordingly, a sample matrix of the present disclosure including a combination of glycine and taurine enables icIEF separation of acidic and basic species from the main peak for PEGylated proteins, allowing the identification/separation, characterization and quantification of discrete PEGylated protein species. By using the sample matrices of the present disclosure to characterize PEGylated proteins by icIEF, repeatability, linearity, accuracy, sample stability, and method robustness are achieved.

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