[Histonet] Osmometer

Robert Chiovetti rchiovetti <@t> yahoo.com
Thu Dec 20 12:11:16 CST 2007

Hi Mauricio,

Well, that's interesting.  The "more modern techniques" still require an instrument to measure osmolality!  Maybe you need to ask someone else in the laboratory...

There are two basic ways to measure osmolality:  vapor pressure and freezing point depression.  In the vapor pressure instruments, you soak a small filter paper circle with the solution, put it in a sealed chamber and measure the amount of heat that is required to vaporize the solution and form an amount of pressure in the chamber.  The freezing point depression machines usually require a little more solution.  It's put in a small chamber, the chamber is chilled, and the temperature is measured at which the solution freezes.  There is sometimes a small vibrating probe in the solution to agitate it while it's cooling down.

At least these are the two old standby methods.  There are probably more freezing point depression osmometers in use than vapor pressure osmometers, but they have both been around for many years!

Maybe you should ask someone else in another lab?


Robert (Bob) Chiovetti, Ph.D.
Southwest Precision Instruments
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----- Original Message ----

I asked to borrow an osmometer from another lab, and was told that they
longer use these, as they have moved on to "more modern techniques". I
really curious to know what these techniques could be.
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