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The Drying Oven vs. Halogen Moisture Analyzer White Paper will be of interest to anyone involved in moisture analysis applications in pharmaceutical, chemical, food, or other industries, as moisture content affects the quality, shelf-life, and usability of a wide array of end products.
This white paper explains and provides practical guidance on how halogen moisture analysis can replace the loss on drying (LOD) using a drying oven method in order to speed up and simplify the analysis.
In the field of moisture determination using loss on drying techniques, a common question is:
"Can the drying oven method be replaced by fast halogen moisture analysis?"
The simple answer is yes, as long as the results obtained by the two methods are comparable. This means that it is necessary to show evidence that the results are equivalent within specific tolerances, which is not such a straightforward question to answer.
This white paper guides the analyst through this process. It explains the key decision criteria surrounding the choice of method and provides practical guidance on how to demonstrate that the two different methods (drying oven and halogen moisture analyzer) deliver comparable results.
In addition, two alternative and acceptable comparison approaches are outlined in this paper: the first approach is based on specific process requirements (tolerances), and the second approach is based on statistical analysis of the data obtained.
| Drying Oven | Halogen Moisture Analyzer | |
| Principle | Thermogravimetry | Thermogravimetry |
| Measuring method | Heating of sample by convection. A sample is dried in the oven for a defined period of time at a constant temperature. Mass is determined before and after drying. The moisture content percentage is determined from the difference in weight before and after drying. | Heating of sample through absorption of IR radiation from a halogen radiator. Continual determination of mass during the drying process. The moisture content percentage is determined from the difference in weight before and after drying. |
| Advantages | • Often reference a procedure (for historical reasons, this procedure often forms part of legislation) • Several samples can be determined at the same time • Large sample volumes possible | • Quick measurement (typically 5 – 15 min.) • Simple handling, no calculations • Compact instrument, no balance or desiccator required • Suitable for at-line use |
| Disadvantages | • Very long determination period (hours) • Substances other than water may evaporate • Prone to errors because of the high level of handling and calculations involved • Unsuitable for at-line use – requires an analytical balance and a desiccator | • Substances other than water may evaporate |
