Interference of Radio-opaque Agents in Clinical Capillary Zone Electrophoresis

Capillary zone electrophoresis (CZE) has emerged as a novel technique for the rapid and effective separation of serum proteins (1)(2)(3)(4)(5)(6)(7)(8). Recently, a multichannel automated system for CZE of human serum proteins (Paragon 2000 clinical capillary electrophoresis system; Beckman Instruments) became commercially available; this system offers a clinically reliable alternative to cellulose acetate and agarose electrophoresis. CZE has the advantage of automation, improved precision, and a faster turnaround time (6)(8). In the conventional methods, quantification of the protein fractions is based on dye binding, whereas CZE uses ultraviolet detection at 214 nm for direct protein quantification via the peptide bonds. We asked whether intravascular agents such as radio-contrast media that absorb at 214 nm would simulate a monoclonal component on CZE. We performed high resolution agarose electrophoresis with the Hydrasys analyzer (Sebia), using Hydragel 15 HR gels (Sebia) according to the manufacturer’s instructions. The serum proteins were separated into the following fractions: prealbumin, albumin, α1-antitrypsin, α1-lipoprotein, haptoglobin plus α2-macroglobulin, β- lipoprotein, transferrin, complement C3, and the gamma globulins. Spectrophotometric analysis was done with a Varian Cary 3 biospectrophotometer (Varian). We combined sera from five adults for the addition experiments. The capillary zone and agarose electropherograms of each of the five sera were normal.