Sample Preparation - Adam Equipment PMB 53 Manual Del Operador

14.0 SAMPLE PREPARATION

Sample preparation is the single most important item for accurate results.
The sample must be prepared so the whole of the sample is heated uniformly
and the moisture is near the surface of the material.
For powders no further preparation is necessary. For most other materials
the sample should be ground, chopped, grated or otherwise made as fine as
possible. Liquids or paste may need to be spread onto or sandwiched
between glass fibre pads to distribute them evenly and thinly. Some
materials that may splatter as they are heated (oils, butter) may need to be
spread on the glass fibre pads or mixed with dry sand. If a substance is likely
to form a surface skin when heated from above then it should be covered by
a pad.
Trial and error is often the only method to find the best method for the
material.
When the sample is placed on the weighing pan it should be spread as thin
and evenly as possible, do not compact the material. Ensure enough material
is used to assure good repeatability of the results. Typically samples of 3 to 8
grams are used. Larger sample sizes will usually produce more accurate and
consistent results.
Some materials will require special preparation. For example when testing
cheese, if the cheese is very soft it may be necessary to use dry sand as a
buffer material so it does not splatter or form a skin. To do this it would be
necessary to prepare the sand by drying it in an oven until you were certain
no moisture remains. Put the sand on the sample pan and tare the analyzer.
Mix the sand with the cheese so you have smooth mixture, spread this
mixture on the sample pan and then do the test.
An alternative to this preparation is to spread the cheese on dry spun glass
gauze to assist in spreading the heat and preventing splatter or skins forming.
Remember to tare the analyzer with the gauze in the weighing pan for
accurate results.
73
| P a g e © Adam Equipment Company 2017