Metrohm 743 Rancimat - Manual (Page 85)

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743 Rancimat ￭￭￭￭￭￭￭￭ 77
2 Check the filling level
￭ Check whether the quantity of the melted sample material rises to
such an extent in the reaction vessel that the air tube immerses
sufficiently deeply. If this is not the case, add more sample mate-
rial.
Preparing samples containing oils and fats
Oils and fats made from products containing oil and fat must be extracted
as follows with petroleum ether (low boiling point) protected from light:
1 Crush the samples
￭ Finely and homogeneously grind oilseed fruit, cocoa beans as well
as other solids in coarse form in a knife mill or another suitable
crushing apparatus (if possible, metal-free).
Note
Oil/Fat extraction through pressing off has not proven effective in
practice.
2 Extraction
￭ Prepare an Erlenmeyer flask 300 mL with normal grinding.
￭ Weigh in between 50 and 100 g (depending on oil/fat content) of
the sample in powder form (e.g. milk powder, cocoa powder,
hazel nut powder) or the finely ground material.
￭ Cover the sample material with a layer of approx. 1 cm of petro-
leum ether (low boiling point).
￭ Extract the oil or fat while continuously stirring for around 12 h
and keeping it protected from light.
Note
In order to carry out at least one double determination on the 743
Rancimat, you have to extract approx. 10 g pure oil or fat, allow-
ing for a certain transfer loss (for more than two determinations
accordingly more is necessary).
￭ Prepare a clean round-bottom flask 250 mL with standard ground
joint and a folded filter.
￭ Filter off, if possible protected from light. Rewash the residue with
a little petroleum ether.