Interference of iodinated contrast media in serum capillary zone electrophoresis

Automated capillary zone electrophoresis (e.g., on the Paragon 2000 CZE, Beckman Instruments) is an alternative to conventional electrophoretic methods for the separation of serum proteins (1)(2)(3). The technique uses ultraviolet (UV) detection at 214 nm for direct quantification of peptide bonds, whereas conventional methods detect the protein fractions by staining with various reagents. CZE has the advantage of improved precision and a faster turnaround (4). Recent reports indicate, however, that the Paragon CZE 2000 masks deficiencies of α1-antitrypsin (5) and that some radio-opaque agents simulate a monoclonal component in the α2-globulin fraction in the CZE electropherogram (6)(7). We encountered an interference from the contrast medium Omnitrast®, which produced an unexpected peak in the α2-zone of the CZE electropherogram. We have now investigated the effect of 12 iodinated radio-opaque media (commercially available in Spain) on instrumentation (Paragon CZE 2000) operated as described by Bossuyt et al. (6). When we used the desalting method described …