Calibration and Uncertainty Estimation for Water Content Measurement in Solids

Rudolf Aro,Ivo Leito,Éric Georgin,Benoit Savanier,Mohamed Wajdi Ben Ayoub

doi:10.1007/s10765-021-02796-y

Abstract

In the field of water content measurement, the calibration of coulometric methods (e.g., coulometric Karl Fischer titration or evolved water vapor analysis) is often overlooked. However, as coulometric water content measurement methods are used to calibrate secondary methods, their results must be obtained with the highest degree of confidence. The utility of calibrating such instruments has been recently demonstrated. Both single and multiple point calibration methods have been suggested. This work compares these calibration methods for the evolved water vapor analysis technique. Two uncertainty estimation approaches (Kragten’s spreadsheet and M-CARE software tool) were compared as well, both based on the ISO GUM method.

Highlights

Moisture metrology has experienced rapid development in recent years, as more stakeholders have realised that improved moisture content control can provide significant gains in process efficiency and/or product quality [1]
The multiple point calibration was less affected by the variability of the calibration measurements as it used multiple determinations—if the only calibration measurement used for single point calibration was biased, there was no way to negate that effect
The study focused on the calibration and uncertainty estimation for moisture determination in solids

Summary

Introduction

Moisture metrology has experienced rapid development in recent years, as more stakeholders have realised that improved moisture content control can provide significant gains in process efficiency and/or product quality [1]. Differential scanning calorimetry (DSC), for example, has been used from measuring the energetic effects of protein folding [4] to polymer biodegradability [5] Another thermal method, thermogravimetric analysis (TGA), has found uses in studies looking into the properties of polymers [6] and pyrolysis processes [7]. It may be necessary to measure water content which requires more selective methods [9] This need has been met by hybrid approaches combining the heating step of LoD, for a robust release of water, with detection cells that are selective for water. One such technique is evolved water vapor analysis (EWV), which has been used in this study

Methods

Results

Conclusion