Karl Fisher determination of residual moisture in veterinary vaccines -- practical implementation in market monitoring.

Residual moisture content plays a significant role in assessing the stability of veterinary vaccines. Analysis of water amount is often a critical parameter, which determines the quality of product, its appearance as well as the expiration date. The aim of the study was to validate a coulometric Karl Fisher method for practical use in the national monitoring of veterinary vaccines market. Immunological veterinary medicinal product (ivmp) for three different animal species - cats, dogs and rabbits - were used. Automated coulometric analysis in chamber without diaphragm was used, as well as a solution for titration, which was a mixture of diethanolamine, imidazole, methanol and sulfur dioxide. The weight of a single sample was 15-100 mg. The most important concern was optimization of the way of transferring a vaccine sample into titration cell, so that atmospheric moisture would not affect baseline drift and repeatability of the results. Humidity level in lyophilized biopharmaceuticals was validated in accordance with the guidelines. The method was linear in the range of one to five percent of water content with R(2) = 0.9998. Repeatability for different sample types was found to be not higher than CV% = 5.9. The method was used for vaccines market monitoring in 2010 and 2011. Thirteen vaccines from the market were tested and all were found to be compliant with official EU guidelines.