Semi-Micro Osmometer K-7400S instructions, V3700
Operation
16
Note:
Any change of the measuring head causes the need for a precali-
bration of the device to adapt the device to the measuring head (see
„7.7.1 Pre-calibration“ on page 21).
The measuring head is placed on the housing plate with the sample tube
rising into the cooling cavity. The device is now ready for measurement.
Note:
The sample volume can be reduced down to a volume of 50 µl. It
is important that all calibrations must be performed with exactly the same
volume as the later sample.
7.2
Standby position of measuring head
Note:
Generally the measuring head should be stored with the attached
sample tube.
While working with the osmometer, use the four columns on top of the
device for temporarily set down the measuring head without sample
tube. In the measurement position, it is not necessary that the feet of the
mea suring head rest on the device.
To avoid sample spilling into the measuring head, it must be held upright.
Fig. 5:
Set-down of the measuring head without sample tube
7.3
Measurement principle and process
The osmotic pressure in a solution is proportional to the freezing point
depression of that solution. An aqueous solution, with an osmotic pres-
sure corresponding to an ideal 1-molal solution, freezes at -1.858 ° C.
An aqueous solution with this freezing point has a concentration of
1 Osmol / kg.
