CSC Scientific Blog
One quiet night, I was musing over moisture analysis and how easy it is to do using loss-on drying. Little did I know what was in store.
As usual when we pose a question, like:
Should you use Coulometric or Volumetric Karl Fischer to measure moisture in your product?
We often get a the reaction, “So Who Cares?” We'll try to answer both questions.
Last week, as I was reflecting on a recent moisture content problem, I recalled our series “Loss-on Drying and Other Moisture Mysteries.” In that series I examined moisture chemistry in products. However, I did little to define moisture content.
Regularly I’m asked the question; “How accurate is this moisture balance?”
The questioner asks for the answer in terms of percent (%) moisture. When I answer “it depends”, I always get the unspoken response, “Why did I ask this stupid idiot?”
When you ask about the accuracy of something like weight or temperature the answers are straight forward and relate to the instruments' precision. For example 25 grams or 50 degrees plus or minus (+/-) 0.1 gram or 1/2 degree.
Percent is Relative
When you ask the question of how accurate is my percentage reading, the answer becomes complicated. It’s complicated because percentage (%) is a relative term. For example, the answer for the result of a Loss on Drying (LOD) moisture test, is based on the size of the sample you use.
Using the example of a LOD moisture test we can understand the concept. The result of this type of test is calculated by subtracting the weight of the sample at the end of the test from the weight of the sample at the beginning of the test. This difference is divided by the initial weight of the sample. This procedure produces a % moisture result.
In the following analysis, the implication s of sample size and instrument precision will be illustrated. This will be based on a sample that has 23.5% moisture and an electronic LOD moisture balance that has a sensitivity of 0.001 grams and repeatability of ± .005 grams.
Loss on Drying (LOD) Moisture Balance analysis is based on drying a sample and comparing the difference in weight before and after drying.
As people who measure moisture, we at CSC Scientific work to find the best technique.Read More
When we first started measuring moisture with Karl Fischer, I was instructed in the complex chemical reactions involved. I was also was told that the process was skittish.Read More
One quiet night, long ago I was musing over moisture analysis and how easy it is to do using Loss-on Drying (LOD). Little did I know what was in store.Read More