LABEC M-MIA-A - Manual (Page 64)

Ultrasonic milk analyser
5.3. Basic principles.
Milk is dried, carbonized and turned to ashes till constant mass. The ashes
received are calculated in percentages.
5.4. Necessary devices and reagents
• Assay balance;
• Crucibles;
• Water-bath or infrared lamp;
• Hot plate or burner;
• Drying-oven with thermal regulator;
• Muffle furnace;
• Exicator;
• Quantity filter.
5.5. Making the determination:
In preliminary tempered and weighted crucible of the assay balance at about
10 g milk is weighted with accuracy up to 0,0005 g. The crucible with the
sample is placed in a water-bath or infrared lamp till the evaporation of milk to
dry state. Then it is carbonized with the burner or on a hot plate, paying
attention not to be splashed out. The crucible is placed in a muffle oven and
turns to ashes slowly, without the sample to be kindled, at temperature 500-
550
о С till white or grey-white ashes. It is tempered in an exicator and is
weighted till the appointed accuracy. Heating up in the oven is repeated till a
constant mass is received.
5.6. Calculations
Ashes content is calculated using the formula
Where:
А – the mass of empty, tempered crucible, g
В – the mass of the crucible together with the milk, g
С – the mass of the crucible with the received ashes, g
5.7. Measurement accuracy
The difference between tow parallel determinations could not be more than
0,02 %.
100
) (
) (
∗
−
−
=
A B
A C
ashes
Operation manual MRC.VER.01-02.10