Automation of Polysaccharide Quantification: A Rapid High-Throughput Assay Enabled by Liquid Handling Technology

Different methods are used today for polysaccharide quantitation, including HPLC and various colorimetric assays. Among these, the anthrone-sulfuric acid assay (anthrone assay) is popular when the sample matrix is suitable, such as in purified polysaccharides and monovalent bulk conjugate components of glycoconjugate vaccines. While relatively safe, quick, and affordable, the anthrone assay requires significant operator time to complete and is not suited to high-throughput processing. Furthermore, the anthrone-sulfuric acid reagent presents a unique challenge to automation efforts due to its corrosive properties. Reported here is an automated anthrone assay via a liquid handling system (LHS). Twenty-three serotypes of pneumococcal (PNU) polysaccharide were quantified with the traditional anthrone assay and subsequently analyzed using the anthrone LHS method. The anthrone LHS method was evaluated for accuracy compared to the manual method and later validated according to ICH Q2 (R2) guidelines. To our knowledge, this is the first fully unattended and corrosion-mitigated anthrone assay validated under ICH Q2 (R2), capable of overnight batch operation. The developed assay can quantify polysaccharides with an accuracy of 81-115%, is precise to a coefficient of variation of <7.0%, and is linear between 30 and 650 µg/mL range (R² ≥ 0.993). The assay can process eight samples per hour, can be utilized in overnight operation, and completes all pipetting, incubation, and data export steps automatically.