The sources of process impurities and pollutants related to production include: impurities from cell matrix (such as host cell protein, host cell nucleic acid), impurities related to cell culture process (inducer, antibiotic, medium components, etc.) and impurities related to downstream process.

The characterization of mRNA structure is one of the key factors for ensuring its safety and efficacy. The previous research and development of mRNA drugs mainly focuses on modifying the structural elements of mRNA, especially the 5 'cap region and Poly A tail. Modifying such structures can effectively improve the intracellular stability and translation efficiency of mRNA.

The structure of the sample is analyzed using various structure elucidation methods, including primary structure, secondary structure and advanced structure, such as molecular weight by mass spectrometry analysis (complete/reduced/subunit/deglycosylation), amino acid composition, N-terminal/C-terminal amino acid sequence or complete sequence analysis, enzymatic digestion peptide mapping (including CDR region identification for antibody), percentage peptide sequence coverage, peptide mass fingerprint, disulfide bond and advanced structure detection.