Advanced Application of Capillary Electrophoresis in High-resolution Serum Monoclonal Protein Detection

Monoclonal immunoglobulin, also known as M protein or paraprotein, is produced by clonal proliferation of plasma cells or B lymphocytes and serves as a key biomarker for monoclonal gammopathies. Accurate detection and quantification of serum M protein are essential for early disease diagnosis, clinical classification, and therapeutic monitoring. This protocol describes a method using capillary electrophoresis (CE) for high-resolution separation of serum proteins. Proteins are separated in an alkaline buffer under high-voltage electrophoresis and detected by ultraviolet absorbance, generating electropherograms that allow clear visualization and quantification of abnormal monoclonal protein peaks. Compared to traditional methods, CE provides improved resolution of the beta region and enables automated, rapid analysis with minimal sample handling requirements. Five representative electropherograms demonstrated M protein migration in the β1, β2, and γ regions, with M protein levels of 0, 44.1% (45.8 g/L), 10.5% (8.6 g/L), 35.5% (28.4 g/L), and dual peaks of 41.3% (46.0 g/L) and 12.4% (13.8 g/L). In a retrospective study of 700 clinical serum samples, CE achieved a positive detection rate of 51.86%, compared with 52.86% for immunofixation electrophoresis (IFE). Using IFE as the reference method, CE demonstrated a sensitivity of 92.70% and specificity of 93.94%. These findings confirmed CE as a rapid, automated approach for screening and quantifying serum M protein in routine clinical laboratories.