Rapid Loss-on-Drying Testing – Sample Size Selection

Sample size is one of the key parameters in the accurate characterization of a material by means of rapid loss-on-drying technology. Performing accurate analysis is often a challenging task, due to the unique characteristics of each material that may influence the method of the analysis process.

Addressing these issues is essential to determine the optimal sample size for performing a rapid loss-on-drying analysis.

Total Volatile Content

The amount of material that will be evolved off during an analysis will significantly influence the quantity of material required for an accurate analysis with an acceptable analysis time. A sample size of few grams (5.0g ± 0.5g) is sufficient for materials expecting losses more than 20%.

For materials with higher volatility, the mass can be adjusted up or down subsequent to the completion of the initial analyses for increasing the repeatability or shortening the analysis time, which relies on the condition that is more preferred by the user.

A larger sample size is required for materials with lower volatility. An initial sample size of 10.0g ± 1.0g is good for materials expecting losses between 1% and 20%. It is recommended to use a sample size of 20.0g ± 2.0g for the analysis of materials expecting losses below 1%.

It is possible to adjust the sample size from these sizes for achieving optimum instrument performance.

Sample Layering

Sample layering is another parameter to be considered in the selection of a sample size for performing the rapid loss-on-drying analysis. Accumulation of the sample material could be the result of using an initial sample size that is too large.

This causes insulating the sample close to the pan from the heat source, which would yield a lower than expected result. To negate this, technicians often increase the temperature, which causes burning of the top layer of the sample material.

This situation can be handled by returning the testing conditions to a lower temperature and decreasing the sample size while increasing the surface area.


Sample size is a crucial factor for performing rapid loss-on-drying analyses, especially for materials that are flammable. If the sample size is too large, the device can get damaged when the material ignites. Conversely, repeatability between tests can get affected if the sample size is too small. For these materials, it is recommended to start with an initial sample size of 1.0g ± 0.2g and increase the sample size in 0.5g increments until achieving appropriate testing conditions.


There are certainly other parameters that can influence the sample size required, and each material will have its own difficulties for identifying the optimal sample size.

Arizona Instrument

This information has been sourced, reviewed and adapted from materials provided byAMETEK Brookfield Arizona

For more information on this source, please visit AMETEK Brookfield Arizona


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