5 2
How to obtain the best results - Section 8
With readily volatile samples, rapid application of the sample on the sample pan is advisable, otherwise,
moisture can escape before the initial weight is recorded; here, use of the manual operating mode is appropri-
ate.
Treating the sample during drying
Occasionally, following recording of the initial weight of the sample and before the actual drying, the test sub-
stance is subjected to further treatment. The halogen Moisture Analyzer from OHAUS offers this possibility in the
manual operating mode.
Such applications could include:
Mixing of quartz sand: moisture which vaporizes during the mixing of the sample is correctly taken into
account in the final result.
Coagulation of protein by dropwise addition of alcoholic solutions. This prevents skin formation during
drying. Added solvent is not recorded in the final result.
Formation of readily volatile azeotropes by addition of solvents insoluble in water (e.g. xylene, toluene).
Note that the addition of solvents can lead to the formation of flammable or even explosive mixtures. With
applications of this type, you should thus work with extremely small amounts of samples and with the necessary
care. In cases of doubt, a careful risk analysis must be performed.
Selection of the optimum sample weight
The sample weight has an influence on both the accuracy of the measurement results and the measurement
time. With large amounts of samples, a great deal of water must vaporize and the moisture determination takes
longer.
To keep the measurement time as short as possible, we advise you choose a low weight for your sample, but
not so low that attainment of the required measurement accuracy is no longer possible.
Accuracy of the results
high
low
Sample weight
0.1g
Measurement time
long
short
Sample weight
0.1g
Correct sample distribution
Incorrect sample distribution
Correct amount
Distribution
Homogenously distributed
Piling
Excessive amount
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