Maintaining the correct humidity for biological samples

What is it about?

Biological samples are often kept in solutions with specific components to maintain integrity. The relationship between the components of a solution and the relative humidity above that solution was measured in 1887 in Grenoble by Francois-Marie Raoult, who gave his name to Raoult’s law that descibes the reduction in the saturated vapour pressure above a solvent when a mole fraction x of some solute is dissolved within it. . These observations have proved very useful but the law breaks down for polymers and there has never been a physical explanation for the relationship. This paper presents a simple explanation for Raoult’s law using statistical mechanics and also shows how this treatment can be extended to polymer solutions, where Raoult’s law breaks down.

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Why is it important?

The control of the RH surrounding samples is important to maintain their integrity and study the effects of increased or decreased humidity.This paper illuminates the machinery underlying a long-observed phenomenon, extends the description to include polymers and allows the accurate prediction of humid atmospheres for specific sample requirements, applicable to a wide variety of fields.