LABEC M-MIA-LA - Manual (Page 67)

Ultrasonic milkanalyser
Operation manual 04.11.09 65/107
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