14. After the solvent has been collected for 2-3 minutes move the ...
air valve to the "evaporation" position and collect the last residue of
the solvent in the condenser trap. (Make sure that the air pump in the
Service Unit is switched on.)
15. Release the extraction cups by raising the handle on the left of the
unit and remove the cups from the Extraction Unit using the cup holder
and place them in the oven (95 - 100°C)for 30 minutes .
16. Gooi the cups in a desiccator.Weigh them (WJ and calculate percentage
of fat according to formula:
W - W
% crude fat = -^- — x 100
w
1
17. After analysis rinse extraction cups with'suitable solvent
and wipe dry with soft paper. Empty thimbles for reuse.
VI. RESULTS AND COMMENTS
The 13 samples were analysed using two different times for the
'boiling extraction" and "rinsing" periods respectively. As can
be seen in table 1 the shorter period was in most cases sufficient
to achieve reliable results. However, there is a slight tendency
to higher values on some of the samples after the longer extraction
period. Also the relative error was found to be slightly lower
(- 1.36 %) for the longer extraction period (45 min.) than for
.the shorter one (- 1.52 %) . Accordingly the 45 minutes extraction
period should be chosen for this type of samples if maximum relia-
bility is the ultimate goal.
As can be seen in table 2 the results achieved on the SOXTEC
system agreed quite well with the results from the three
laboratories using classical Soxhlet equipment and 18 hours dura-
tion of extraction in the same solvent. The differences between
1980.01.15 RA/ML AN 23/80
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