Molecular mass, determination osmotic-pressure method

This equation is used to determine the molecular mass M2 using the method of osmotic pressure. 

The molecular weight of a protein may be determined by the use of thermodynamic methods, such as osmotic pressure measurements and sedimentation analysis in an ultracentrifuge. Osmotic pressure is sensitive to the number of molecules (particles) in solution, and if the total mass of protein in solution is known, the molar weight can be estimated. The sedimentation of protein molecules in a centrifuge depends directly on the mass of each molecule. 

The most accnrate method for determining molecular weights is by high-resolution mass spectrometry (Section 9.17A). A variety of other methods based on freezing point depression, boiling point elevation, osmotic pressure, and vapor density can also be used to determine molecular weights. 

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