Separation of iron-free and iron-saturated forms of transferrin and lactoferrin via capillary electrophoresis performed in fused-silica and neutral capillaries

A capillary electrophoresis-based method for the cost-effective and high efficient separation of iron-free and iron-saturated forms of two members of transferrin family: transferrin and lactoferrin has been developed. The proposed qualitative method relying on the SDS application allowed us to separate iron-free and iron-saturated forms of these proteins, as well as human serum albumin, used as an internal standard. Owing to the distinct migration times under established conditions, the combination of transferrin and lactoferrin assays within a single analytical procedure was feasible. The performance of the method using a fused-silica capillary has been compared with the results obtained using the same method but performed with the use of a neutral capillary of the same dimensions. Neutral capillary has been used as an alternative, since the comparable resolution has been achieved with a concomitant reduction of the electroosmotic flow. Despite of this fact, the migration of analytes occurred with similar velocity but in opposite order, due to the reverse polarity application. A quantitative method employing fused-silica capillary for iron saturation study has been also developed, to evaluate the iron saturation in commercial preparations of lactoferrin.