1 Introduction
1.1.1 Application Restrictions of the Osmomat auto
-
The unit is not intended for determining the osmolality of dilutions.
-
Only the osmolality of aqueous solutions can be determined.
Plausibility checks of the results must be performed by the doctor with the support of the pertinent
literature.
1.2
Measurement Method of the OSMOMAT auto
The OSMOMAT auto is a cryoscopic osmometer that measures the freezing point depression to
determine the total osmolality of aqueous solutions.
The freezing points of pure water and a solution are measured and compared. Whereas water has a
freezing point of 0°C, a solution with a saline concentration of 1 osmol/kg has a freezing point of
-1.858°C. That means that one mol of a given non-dissociated substance (6.023 x 10
23
parts diluted in
one kilogram of water) lowers the freezing point of a solution by 1.858°C. The following definitions are
used in calculating osmolality:
C
osm
= osmolality [osmol/kg]
T
= freezing point depression [°C]
C
osm
=
Δ
T / K
K
= 1.858°C kg/osmol freezing point constant
The osmolality indicates the concentration of all osmotically active dissolved parts in the solvent.
Since the freezing point depression is directly proportional to the dissolved parts, the OSMOMAT auto
measures the osmolality directly.
1.3
Reproducibility in the OSMOMAT auto
Measurement
display
LCD display, 4 lines with 20 characters
Measuring range
0 to approximately 2500 mOsmol/kg
Resolution
1 mOsmol /kg or 1 mOsmol/digit over the entire measuring range
Reproducibility
Sample volume 50µl
#
±1.0%
8 |
Introduction
