Metrohm 892 Professional Rancimat - Manual (Page 42)

4.3 Determinations
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892 Professional Rancimat
Solid samples (e.g. nuts)
Prepare the sample as follows:
1 Place the reaction vessel on a scale using a 6.2628.000 holder.
2 If necessary, pulverize the sample material and weigh it directly in the
reaction vessel. Normally, 0.5 g of sample material is used.
Alternatively you can melt the emulsion fats (e.g. butter, margarine) at a
temperature exceeding the melting point of these fats by 10 °C (i.e. at
approx. +50 °C) centrifuge them and pipette off the resultant oil phase.
4.3.2 Preparing the instrument and the accessories
The cleanliness of instrument and accessory parts is an indispensable pre-
requisite for reliable, reproducible and correct analysis results. Even
the slightest contamination could catalytically accelerate the oxidative
decomposition and lead to completely incorrect results. Therefore, always
observe the instructions for use of measuring and reaction vessels in this
chapter.
Check and prepare the instruments and vessels as follows:
1 Checking the positions for reaction vessels
￭ Check whether the positions in the heating block are clean and
empty.
Blow out contamination and dust in the positions with nitrogen.
If the instrument is not used, always seal the corresponding posi-
tions with the stoppers.
2 Filling the measuring vessels
NOTE
Only use measuring vessels and accessories which are abso-
lutely clean and in a flawless condition.
￭ Fill the cleaned measuring vessels with 60 mL distilled water
each.
For analysis times of more than 24 h approx. 7 mL more distilled
water must be added per day to compensate for the evaporation
loss, so that the electrodes remain safely immersed.