Ohaus MB45 MOISTURE ANALYZER Manual - Manual (Page 50)

48 MB45
8.2 Sampling and sample Preparation (Cont).
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 appropriate.
Treating the sample during drying
Occasionally, following recording of the initial weight of the sample and before the actual drying, the test
substance 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.