Freeze-dried meningococcal vaccine: Total error assessment of a near-infrared method for water content determination

Accuracy of reference values obtained by the reference method is essential to ensure the quality of a near-infrared (NIR) model. The purpose of this study was to assess the accuracy of a newly developed NIR analytical method for the determination of water content in a freeze-dried meningococcal vaccine by evaluating not only uncertainties associated with the calibration model and NIR measurement procedures but also systematic error arising from the reference Karl-Fischer method. An experimental design based on the standard addition method (SAM) in freeze-dried vaccines is proposed for total error assessment of the NIR analytical system. The accuracy profile showed that the NIR model successfully determined water content over the 1.0-6.7% range. The SAM enabled overall proportional error assessment, which yielded a slope of 1.01. The present study confirmed the suitability of the proposed NIR analytical method for the determination of water content in the freeze-dried meningococcal vaccine. Furthermore, assessment of the overall proportional error proved that the NIR analytical method could be used to accurately estimate differences in water content, therein surpassing the reference method as the method of choice for determining intra- or interbatch variability as well as stability.