Osmolality and osmolarity testing
Osmolality and osmolarity indicate how many dissolved substances a liquid contains. The tests reveal the amount of osmotically active substances in the sample and are used as quality control measurements in industries including pharmaceuticals, supplements, and food production.
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What are osmolarity & osmolality?
Osmolarity and osmolality are ways to measure and report the osmometry of a solvent. Osmometry can be expressed in two ways: osmolarity describes the number of solute particles per liter of solvent (osmol/L or Osm/L), whereas osmolality reports the number of osmoles (Osm) of solute per kilogram of solvent (osmol/kg or Osm/kg). Osmolarity is also known as osmotic concentration.
How are osmolarity & osmolality measured?
A typical technique used in osmolality tests is the freezing-point depression test. The freezing point depression osmometer measures the freezing point of the solution to determine its concentration. The freezing point of a solvent lowers when another compound is added. This means that a liquid with dissolved compounds has a lower freezing point than a pure solvent.
The freezing point correlates linearly with osmolality; the higher the osmolality, the lower the freezing point.
What are osmolarity & osmolality analyses used for?
Osmolality analysis gives information about the isotonicity, consistency, formulation, and stability of the sample. Both analyses are often used in the pharmaceutical industry as quality control measurements before placing liquid drugs on the market (as part of batch release testing). Also, the food industry often uses osmolarity and osmolality analyses for process development and quality control.
Sample preparation and requirements
To obtain reliable results, samples must have low viscosity. The accuracy of osmolality and osmolarity tests may be impaired if the solution is colloidal or has a high concentration of dissolved compounds. Samples with high concentrations of dissolved compounds can be diluted before the analysis to lower the concentration.
One partner for all your osmolarity and osmolality testing needs
Measurlabs provides reliable osmolarity and osmolality testing for pharmaceuticals and liquid medical devices using European and American pharmacopoeial methods (Ph. Eur. 2.2.35 and USP <785>). Large sample batches are processed efficiently without compromising accuracy, ensuring timely and precise results.
More than 1,000 companies worldwide have already selected Measurlabs as their testing partner for dependable service and high-quality analyses. Use the form below to request a quote for your project.
Suitable sample matrices
- Aqueous samples
- Liquid pharmaceutical solutions
- Liquid food supplement solutions
- Sports drinks
- Beverages
- Other liquid goods
Ideal uses of osmolality and osmolarity tests
- Analysis gives the exact concentration of osmotically active substances in a solution.
- Tonicity is a key measurement for finding out the drug absorption qualities.
- The method is used to measure tonicity of sports drinks.
- Quality control of liquid pharmaceuticals and supplements.
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Frequently asked questions
Osmolality and osmolarity are often used in the pharmaceutical industry as a quality control measurement before liquid drugs are released to market.
Osmolality analysis gives information about isotonicity, consistency, formulation, and stability.
The analysis gives insight into process development, brewage, and food product quality control.
Sample should have low viscosity.
Accuracy of the test decreases if the sample has very high molarity. Samples with high concentrations of dissolved compounds can be diluted before the analysis to lower the concentration.
Liquid samples with not too high viscosity and not too high concentration.
Osmolalitys definition is Osmoles of solute per kilogram of solvent (osmol/kg or Osm/kg)
Osmolaritys definition is Osmoles of solute per liter of solution (osmol/L or Osm/L)