Page 18 of 51
OSMOMAT 050 User Guide
Version 1.1 (2011-10-12)
4.3 Filling the Supply and Waste Bottles
Add the Ringer's solution mentioned earlier to the supply bottle and screw on the cap.
Place the supply bottle in the rear position on the bottle tray.
The waste bottle collects the measured sample and the used solvent required to rinse the measuring
cell. The waste bottle must have a constant
fill level of minimum 10 mm
required during measure-
ment and calibration as hydrostatic reference value for the zero point.
For safety reasons (risk of infection), we recommend adding a small amount of a commercially availa-
ble disinfectant and daily emptying and rinsing of the bottle when the device is in use.
4.4 Preparing the Semipermeable Membrane
4.4.1 Selecting suitable membranes
The semipermeable membrane is a main component of the osmotic cell. The defined pore size allows
only the lower molecular solvent and the electrolytes to permeate, while the higher molecular sub-
stances of the measurement solution are retained. In addition, the membrane material seals the os-
motic cell.
The pore size or pore size range is the typical factor for the retention and is called "cut-off". The mem-
branes used for membrane osmometry usually have a cut-off between 5,000 and 30,000 dalton. The
pore sizes specified by the membrane manufacturers are reference values only. They do not indicate
the actual pore size or an existing pore size distribution.
Increasing the cut-off may result in lower colloid osmotic pressures.
Only membranes with very thin layers containing a supporting material for mechanical reasons
(so-called two-layer membranes) can provide adequate permeability. Depending on the manufacturer,
both layers are made of the same or different materials. Aqueous solutions can be used for virtually all
membrane materials.
It is strictly necessary that the membrane has a diameter of 25 mm [+0, -0.5 mm]!
Membranes from other manufacturers can be slightly bigger and in that case must be trimmed with
scissors.
We recommend a membrane material with a
cut-off
(retention)
of higher than 10,000 g/Mol
and
of higher than 20,000 g/Mol.
The membranes are typically supplied dry with the pores filled with glycerin. The dry membranes sup-
plied by Gonotec are each separated by filter paper. The membrane must be conditioned in water
before installation in the measuring cell of the OSMOMAT 050.
Summary of Contents for OSMOMAT 050
Page 2: ......
