PRJECT SUMMARY Fast evolution of blockbuster biologics such as monoclonal antibodies, antibody drug conjugates, fusion proteins, and gene therapy, is creating a strong demand for efficient analytical tools to characterize and monitor product variants that could negatively impact safety and efficacy. During production in cell culture, formulation, and storage, protein therapeutics can undergo post-translational modifications that could lead to charge variants (CVs). CVs are product variants with a net charge different from that of the intended product. The International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines identify CVs as a critical quality attribute because of their potential impact on the quality, safety, and efficacy of the product. Also, the U.S. Food and Drug Administration guidance recommends a comprehensive characterization of CVs in regulatory submissions. As a result, analytical monitoring of CVs is routine in product and process development, quality control and lot release. In the biopharmaceutical industry (biopharma), there is a growing interest in characterizing CVs with native mass spectrometry (MS) to ascertain the underlying post-translational modifications and potentially correlate with biological functions. For CVs characterization at the intact protein level, efficient separation is a critical step before MS detection to separate the variants, reduce sample complexity, and allow the detection of low abundant species. The most widely used separation techniques for CVs analysis in biopharma are (imaged) capillary isoelectric focusing and ion exchange chromatography but their applications for CVs characterization in native state are limited due to either inadequate resolution or incompatible separation conditions. GMJ Technologies (GMJ) is developing a high-resolution native capillary zone electrophoresis with native mass spectrometry for CVs characterization. Our approach combines multiple innovative solutions in capillary surface chemistry that produces high resolution of CVs by capillary zone electrophoresis, a novel optical-electrospray interface that provides inline optical and native mass detections, and a sensitive nanoflow electrospray mechanism that preserves proteins’ native conformation. With this innovation, GMJ aims to address a gap in the characterization and quality control of protein therapeutics from research to commercialization. By eliminating several laborious steps, the proposed technique will significantly improve the efficiency in the characterization workflow for CVs, improve the analysis precision and sensitivity, provide cost-saving benefits, and contribute to development and manufacturing of novel biologics and protein-based medicines.