The Use of Osmometers in Medicine and Industry

Osmometers provide the means by which to measure a phenomenon known as osmotic pressure which, in turn, may be best described as the pressure that is required in order to inhibit the process known as osmosis. The latter is a property of solutions that tends to force water through membranes that are impermeable to solids such as cell walls, until the concentrations of dissolved solids on both sides of the membrane become equal. The lower the concentration of solute, the greater the pressure a solution is able to exert. Clearly then, that pressure provides a useful basis for the measurement of the amount of dissolved substances in various fluids.

In addition to their effect on this important property, the presence of dissolved solids and their concentration acts to depress the freezing point or vapour pressure of the solvent by creating a sort of anti-freeze effect. Osmometers commonly address one of these effects to measure the extent of any depression which, in turn, indicates the total concentration of dissolved solids present in plasma and other body fluids and which is commonly referred to as osmolality.

In medicine, plasma osmolality provides the clinician with a valuable measure of the body’s electrolyte-water balance and should normally fall; within the range of 285-295 milliosmoles per Kilogram.  The measurement is obtained using freezing point or vapour pressure depression instruments and is an indicator of the difference between intracellular and extracellular pressures. This balance is critical as low pressure external to cells forces water into them and can cause them to burst (cytolysis). Determination of osmolality contributes to the information needed to determine the means to restore balance and this will normally be achieved by means of a suitable intravenous drip.

Just like osmometers, the body also has the means to monitor osmolality and to respond to changes by either increasing or decreasing the release of the antidiuretic hormone (ADH). In the case of dehydration, the increased ADH production triggers the increased reabsorption of water by the gut and is accompanied corresponding reduction to the flow of urine by the kidneys and a rise in its concentration. In cases of lowered plasma osmolality, ADH production is depressed and those natural physiological mechanisms applied by the body to conserve water will then function in reverse.

The applications for this type of instrumentation are certainly not confined to the hospital and the clinical laboratory. In practice there is also an important role for osmometers in industry and in the pharmaceutical sector in particular. Here osmometry is often the preferred technology use in the measurement of the, often minute, quantities of active ingredients present in various formulations. In either case, the operative tasked with these measurements is likely to need quick and accurate results that must often be obtained using very small samples.

At IEPSA, we appreciate the importance of precision and reliability and, during almost 35 years of operation, we have always employed a policy of sourcing all of our analytical and diagnostic products exclusively from manufacturers that have earned a reputation as leaders in their respective fields. As a consequence, our efforts to source the most reliable osmometers led us to Advanced Instruments – an established, US-based, global operation that specialises in equipment for the clinical, food processing, microbiological and biotech sectors including the pharmaceutical industry.

From their factories, we offer two advanced units designed for precision measurement of osmolality in a wide range of applications. Your choice of instrument is most likely to be determined by the demand for this type of testing and so we offer equipment with which to perform both single and multiple measurements. Both require only 20 microliter samples and the company’s Model 3320 is able to provide a result in just one minute and with a level of accuracy and precision that has made it a world-best.

While it may take a full 30 seconds longer, the Model 2020 can handle 20 samples simultaneously and so can be a huge timesaver in the busier laboratory. Ease of use, internal diagnostics and built-in statistical analysis are common to both as is automated calibration to ensure your results are always dependable. The 2020 offers the additional facility of an on-board printer. For even bigger workloads, Advanced Instruments has now released a fully-automated system to which it has assigned the model name A20.

IEPSA is your guarantee of top quality equipment, consumables and expert backup service for a wide range of instruments from analysers to osmometers.

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