Osmometer

23453

Wescor 5500 XRS

The Wescor 5500XRS vapor pressure osmometer requires a sample volume of only 2 to 10 microlitres (10 microlitres for routine operation). Extended range with a switch on the back (hold/run) which disables the electronics that let you put a sample in and let it equilibrate over time. Usually used with plant sections, because they take longer time to equilibrate. Process time: 64 seconds. Range: 0-3000mmol/kg. Because the indication is based on the measurement of vapor pressure of the specimen, the method has many advantages over the freezing point depression method. Vapor pressure and freezing point are among the colligative properties of a solution. Compared with pure solvent, these properties are altered in proportion to the number of solute particles dissolved in each kilogram of solvent (water in the case of biological solutions). Thus, a measurement of either property affords an indirect means of determining solution concentration, or osmolality. The merits of the vapor pressure method stem from the fact that it does not require an alteration in the physical state of the specimen. Other advantages include: a) routine operation on microsamples of any biological solution, including whole blood, serum, plasma, urine, and sweat, as well as complex specimens such as tissue samples. b) Avoidance of measurement artifacts that arise in freezing point depression measurements due to elevated viscosity, particulate matter, inhomogeneities or other physical characteristics of the sample. c) Superior reliability because the measurement is accomplished largely by electronic rather than mechanical means. * One small problem with this particular unit is when an empty sample tray is pushed in, unit will go through sample processing loop but does not revert back to autocal mode, it will beep after several minutes as if a sample disc is left in the chamber. So, each time when a run is finished and an empty tray is pushed back to the chamber, the reset button at the back must be pressed. This drawback does not affect the performance of the unit, but cannot be corrected.

Used

115 Volts, 50-60 Hz, 30 W

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