Separation and detection of vitellogenin in fish plasma by capillary zone electrophoresis

A method for coupling capillary zone electrophoresis (CZE) with rapid membrane chromatography purification (RMCP) was established for the analysis of vitellogenin (VTG) in male fish plasma induced with 17ß-estrodiol. CZE analyses of purified VTG were performed in a buffer containing 25 mM sodium borate (pH 8.4). A 50 μm i.d. fused-silica capillary was used for separation and the detection was carried out by UV-diode array at 214 nm. Inter- and intra-assay variabilities of the proposed method were less than 10.06 and 1.95%, respectively. The method has good linear relationship over the scope of 15–2250 μg/ml with a correlation coefficient of R2 = 0.9965 and a detection limit of 7.0 μg/ml. The established CZE method was also applied to directly separate and identify VTG from fish plasma. The results indicated this method could minimize interferences from plasma proteins, allowing the detection of at least 62.5 μg/ml of VTG proteins in total proteins. This is a rapid and easy method to determine the quantity and purity of VTG compared to Bradford method and SDS-PAGE.