Determination of poorly separated monoclonal serum proteins by capillary zone electrophoresis

A capillary zone electrophoresis (CZE) technique was developed for the determination of poorly separated monoclonal serum proteins by agarose gel electrophoresis (AGE). A P/ACE 5500 capillary instrument (Beckman) was used under the following conditions: 57 cm×50 μm I.D. fused-silica capillary, pH 9.6 borate buffer, and 214 nm on-line detection. Sixty patients (61±13 years) with a well isolated (n=24, group A) or poorly separated monoclonal band(s) by AGE (n=36, group B) were included in this study. Within- and between-run precision for CZE was below 4% for albumin and 7% for γ-globulin. A 100% (group A) or 61% agreement (group B, more bands detected by CZE in 10 cases) was obtained between CZE and AGE for the number of monoclonal bands. In group B, quantification was possible in 92% of samples by CZE vs. 64% by AGE (P<0.05, chi-square). The proposed CZE method appears as an additional helpful technique for the determination of poorly separated monoclonal serum proteins by AGE.