Selecting Moisture Analyzer Configuration Parameters
It is important to remember that the term “moisture” includes not only water but any effluent that can be driven off by heat, such as fats, distillates, alcohols, etc... Anything that causes the sample to become lighter will be interpreted as moisture being driven off, including combustion of the sample. The object is to evaluate the sample, not to cook it.
If time is of the essence, and in moisture analysis it frequently is, then here are some things that will reduce your analysis time;
1. Make the sample size small, usually 3g to 5g is adequate. Making the mass of the sample small means it will heat faster and shorten the analysis time.
2. Knowledge of the physical and chemical properties of your sample material will serve you well in selecting your test parameters. If you expect to determine the water content of your sample you must be sure that you keep your final temperature below the decomposition temperature of the ingredients.
3. be sure that the sample is spread out fairly uniformly on the sample pan so that the heat distribution is uniform. Avoid mounds and lumps.
4. If your analyzer has a rapid temperature run up mode use it if your sample can tolerate high temperature for a short period of time. These modes use maximum wattage to heat the sample oven to maximum temperature as rapidly as possible and hold that temperature for a fixed interval of time and then drop back to a preset temperature for the balance of the cycle.
5. Select your choice of an automatic cutoff profile carefully. Use the steepest one that provides consistent results. It is not necessary for you to drive all the moisture out of a sample in order to predict the final moisture content. Selecting an aggressive cutoff profile can save a great deal of time.
6. Use sample pans with clean smooth surfaces to allow for even distribution of the sample. Be sure the samples are homogenized for uniform results.
7. Keep the oven clean. Heating extraneous materials will slow the process.
8. Use a reference substance to periodically check the calibration of your analyzer. It will save you ti8me in the long run by avoiding the need to repeat entire tests.
Remember, time is important, but you only waste it when your results are invalid.