Determination of the minor whey protein bovine lactoferrin in cheese whey concentrates with capillary electrophoresis

In our present work we present the determination of bovine lactoferrin in whey concentrates as they are typically produced by milk and cheese industry after production of cheese. Due to the high total protein content the analysis of whey concentrate samples is difficult and even not possible by using capillary zone electrophoresis with UV detection. To enhance the detection sensitivity we applied a more promising approach by using affinity interactions in combination with laser-induced fluorescence detection. By mixing fluoresceine isothiocyanate (FITC)-conjugated polyanionic lipopolysaccharide with the mostly positively charged lactoferrin we found a significant migration time shift which is clearly dependent on the concentration of the added protein. In the second approach we developed an immunoassay using FITC-conjugated specific antibody against bovine lactoferrin. The results of the immunoassay measurements were compared with data obtained by standard enzyme-linked immunosorbent assay analysis. (C) 1998 Elsevier Science B.V. All rights reserved.