Osmomat 050 Colloid osmometer

The Osmomat 050 was especially developed for use in intensive care units.

It is designed to be used on a 24 h/day 7 day/week basis and the system is always ready to collect data. The system performs all cleaning and control operations during the stand-by period so that the user can perform a measurement at any time. After performing a measurement, the Osmomat 050 is automatically cleaned so the next measurement can be performed as required.


  • high-performance measuring cell
  • minimum sample volume
  • simple injection of the sample solution (plasma or serum, whole blood not recommended)
  • measuring time < 1 minute
  • automatic zero setting
  • user selection of the pressure dimension (mm Hg), (cm water column) or (k-Pascal), respectively
  • display of the first result and storage of a second value serve as a control of the equilibration of the system
  • automatic rinsing of the measuring cell after each measurement
  • simple calibration with hydrostatic pressure differential
  • automatic stand-by function over longer periods of time

Key data

Measurement volume
< 10 µL
Sample size
> 100 µL
Measurement time
1-3 Minutes, Depending on membrane type
Measurement format
99.9 mm Hg, 9.99 k-Pascal
<± 0.5 mm Hg
Significant figures
3 places
Zero point determination
Membrane material
Two layered membrane, each layer is able to retain compounds with molecular weight > 10,000 - 30,000 Dalton
Recorder output
2mV/Digit, ±10%, can be set for recorder compensation with 1 Volt output
Direct pressure measurement via difference in hydrostatic pressure
1. Stand alone wash of the upper half of the cell is available to prepare the cell
2. Storage of the results
3. Storage of all data values over a specified time period after the first measurement

Measurement: Colloid osmometer

Colloid osmometer

The colloid-osmotic pressure is measured by means of an osmotic cell. The lower half of the osmotic cell is closed off to the environment and is filled with electrolyte-containing Ringer's solution. The upper half of the cell is open to the environment and is filled with a colloid-containing solution.

The two halves of the cell are separated from each other by a semipermeable membrane. This membrane possesses defined pores through which only water and electrolyte molecules can permeate.

Due to the osmotic pressure differential of the two solutions, solvent permeates from the lower into the upper half of the measuring cell until an equilibrium is reached between the underpressure in the lower half of the cell and the osmolal concentration of the colloids. An electronic pressure measuring system, which is mounted into the lower half of the cell, transduces the underpressure into an electric signal, which is shown on a digital display.


The colloid osmometer is suitable for routine measurement and research in medical applications.

Due to the high degree of automation of the measuring and control functions of the Osmomat 050, the operator interaction is reduced to a minimum. This ensures that the instrument is always ready for measurement and the instrument is especially suitable for application in intensive care units.

Typical applications for the Osmomat 050 include the measurement of the colloid-osmotic pressure with blood loss, hypalbumenia, albumin therapy for the prevention of lung edemas and all diseases resulting in a change of the colloid-osmotic pressure.