Samples quantity
Increasing number of tested samples also increases statistic measurement certainty.
Quantity of samples depends on uniformity of tested material, its purity, accuracy of applied
measuring method and anticipated accuracy of obtained results.
Mechanical disintegration of the material intended for measurement
Applied disintegrating method should be selected appropriately to tested material.
Substances that are hard and brittle (crisp) can be disintegrated by cutting. Grinding such
substances may cause their heating and thus humidity vaporization, resulting in unreliable
measurement results. Unless a substance can be prepared for measurement otherwise than
grinding, any possible moisture content loss should be calculated.
Use of high-silica sand
Ensuring optimum substance drying requires that a sample has the largest possible surface
for moisture content evaporation. Test results of moisture content for substance with surface
in a form of a shell (e.g. glucose syrup) or doughy (e.g. butter), can be much more reliable if
a sample is mixed with a dried high-silica sand (improvement of measurement accuracy and
repeatability).
While using mixture, disposable weighing pan with extended brim must be applied (greater
volume of a sample).
Grease in a form of paste or melting substances
Such substance requires testing with use of a filter made of glass fibre, which considerably
increases active evaporation surface by separating the substance between the fibre. Initial
filter drying is necessary only in case of measurements which require very high accuracy.
Liquid substances
It refers to liquid substances, which by creation of drops on their surface, caused by surface
tension, may render difficulties in drying process. In such cases, use a glass fibre filter to
shorten measurement time. The filter separates tested liquid around the fibres, and
increases active evaporating surface. Initial filter drying is necessary only in case of
measurements which require very high accuracy.
Leather-structure or temperature sensitive substances
In case of such substances use a glass fibre filter. While testing, a substance is placed on a
drying pan, and sample surface is covered with a filter, which protects the sample from direct
heat radiation. In such case, the sample is heated by convection (which is milder than
radiation).
Substances containing sugar
The surface of such substances may caramelize during testing procedure. Therefore, it is
recommended to use thin layer of a sample, and moderate drying temperature.
Sample distribution on a pan:
Loose substance
Dried in their natural state, i.e. in their natural form, or
disintegrated. Sample disintegration causes smaller dispersion
between the following measurements. Sample mass should not
be too high. Evenly spread the sample on whole surface of the
drying pan.
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