Thiomersal (also called thimerosal or merthiolate) is an organic molecule containing mercury, which has been widely used as preservative for vaccines and eye drops. To minimize the risk for consumers, authorities limit the mercury content. Voltammetry or polarography offers a simple and accurate determination of trace amounts of mercury without prior sample preparation.

Thiomersal’s primary purpose is to prevent microbial growth in vaccines, eye drops and other pharmaceutical and cosmetic solutions during the products’ storage and use. For consumer protection, authorities introduced limit values for thiomersal. In the European Union typical limit values are 0.007% (as Hg) in eye products (EU Commission Regulation 1223/2009) or up to 25 μg thiomersal per vaccine injection dose for vaccines distributed in multi-vaccine containers.

Voltammetry or polarography can determine thiomersal specifically without interferences from other components in vaccines or pharmaceutical and cosmetic solutions down to the low mg/L range. Voltammetry provides a viable alternative to expensive spectrometric analysis, such as ICP-MS or AAS, with low acquisition and running costs. No sample preparation is required, and vaccines or pharmaceutical solutions can directly be analyzed on their thiomersal content. To learn more about the method, read our free Application Note on this analysis.

Learn more in our Application Note "Thiomersal in eye drops"