1 THE OSMOMAT 070 VAPOR PRESSURE OSMOMETER ...

38 User Guide OSMOMAT 070 Version 1.1
Enter the parameters for measurement in the Parameters screen. The values of the last calibration are
preallocated. If you change a parameter, you will see a warning message that the device is not
calibrated with these parameters and that it is not advisable to perform a measurement under these
conditions.
If all parameters on the screen correspond to the test setup, you can start the measurement by
clicking Measure.
The screen for entering a sample net weight appears. Enter the sample name, a sample number and
the net weights of the different sample concentrations. Net weights should entered in the form of
grams of the sample per kilograms of the solvent. Chapter 3.1.6 explains how to make a sample for
molecular weight determination.
Figure 4-10: Example: Entering sample net weights
4.2.2 Performing the measurement
A requirement for determining molecular weights is that the measurement system should be prepared
for a measurement and a cell constant determined by calibration. It is important to perform the
measurement under the same conditions (temperature, probe numbering and A/B positioning,
sampling time, solvent) as the calibration.
The substances to be measured must be fully soluble and should not chemically interact with the
solvent.
When making solutions, you should set the osmolal concentrations as high as possible. At least three
different concentrations that are 2 and 3 times greater than the lowest concentration must be
measured. Perform the measurement in the same way as the calibration.
38 User Guide OSMOMAT 070 Version 1.1