Investigations on the binding of ethylmercury from thiomersal to proteins in influenza vaccines

Binding of EtHg+ to the protein fraction was shown by means of ultrafiltration and TXRF in a qualitative matter. SEC/ICP-MS was applied to gain more information about the molecular weight of the bound protein and quantitative information. First experiments showed the necessity of a rinsing step during elution with a thiol-containing compound to prevent unspecific binding or mercury species to the chromatographic system. Adduct formation of EtHg+ and a high-molecular compound could be observed for different concentrations of EtHg+ applied. The mercury-containing fraction was larger than 133 kDa, indicating binding to hemagglutinin, which is the active ingredient in influenza vaccines. The applied SEC/ICP-MS method allowed for external calibration with EtHg+ and a binding of 141 μg L−1 Hg was shown for a vaccine solution that was incubated with EtHg+ (25 mg L−1 Hg).