Biomedical Products Division:
Vapro Vapor
Pressure Osmometer
Model 5520
The most advanced, easy to use osmometer ever developed.No other vapor pressure osmometer has the credentials of Wescor's Vapro Vapor Pressure Osmometer. Since 1973 when Wescor introduced its first vapor pressure osmometer, the vapor pressure method has proven itself in thousands of laboratories and myriad applications. Our customers have rendered a clear verdict-vapor pressure osmometry is superior to all other methods:
"Vapor pressure measurement is the fastest and easiest method of determining osmolality, and the thermodynamic limitations of vapor pressure osmometry are least restrictive. For these reasons, vapor pressure osmometry is the method of choice for most fluids in biology and medicine in which water is the solvent."1
The fundamental advantages of vapor pressure osmometry are now embodied in the most intelligent osmometer ever developed. Wescor's Vapro Vapor Pressure Osmometer offers an intuitive approach that frees you from intensively "managing" an instrument.
Why Vapor Pressure?
The Vapro Vapor Pressure Osmometer method determines osmolality at room temperature with the sample in natural equilibrium. This precludes cryoscopic artifacts due to high viscosity, suspended particles or other conditions that can interfere with freezing point determinations, giving Vapro a much broader range of error free applications.
Easy CalibrationWith the Vapro osmometer, say goodbye to frequent and intricate calibration procedures. Vapro is self-calibrating and exceptionally stable. Calibration is verified using osmolality standards. If recalibration is necessary, simply select the calibration option. Calibration is then performed and verified by the instrument.
Customer SupportWescor osmometers have established an unrivaled record of reliability over all other osmometers. This is backed by Wescor's strong commitment to customer service. You will always find the help you need from our knowledgeable and friendly service staff.
1Sweeny, T.E. and Beuchat, C. A., Limitations of methods of osmometery: measuring the osmomolality of biological fluids. Am J. Physiol. 264 (Regulative Integrative Comp. Physiol. 33) R469-R480, 1993
How It Works
In most solutions, changes in concentration are accompanied by linear and proportional changes in the cardinal colligative properties of the solvent-vapor pressure, freezing point and boiling point. Measuring any of these properties provides an indirect indication of osmolality, but among them, only vapor pressure can be determined without a forced change in the sample's physical state.
In the Vapro osmometer, vapor pressure is determined thermometrically by a fine wire thermocouple suspended in a small vapor space above the specimen in a sealed sample chamber. During a measurement cycle, the thermocouple undergoes a series of microprocessor controlled temperature changes.
Step 1After sample insertion, temperature and vapor pressure naturally equilibrate in the sealed chamber. The thermocouple senses the exact temperature of the air above the specimen, and the microprocessor set this value as the null, or reference point for the measurement.
Step 2
Next, the thermocouple is Peltier-cooled below the dew point temperature. Microscopic water droplets begin to condense upon the thermocouple surface.
Step 3The microprocessor then allows the thermocouple temperature to be controlled exclusively by the water condensing upon it. The heat of the condensation causes the thermocouple temperature to rise, converging upon the exact temperature at which condensation ceases. This stable condition is achieved approximately one minute after sample insertion.
Step 4The point of temperature stability is the dew point temperature. The final readout on the instrument display is proportional to the dew point temperature depression with a resolution of 0.0003 °C. Because dew point temperature depression is an explicit function of vapor pressure, the instrument can be calibrated to report results directly in Standard International units of osmolality, mmol/kg.
The Vapro Osmometer brings unprecedented simplicity, convenience and accuracy to the routine determination of osmolality to help meet the demands placed on today's clinical laboratory.
Auto-calibration, self-diagnostics, statistical analysis, and computer interface/printout capabilities increase the utility of this instrument for any busy laboratory. The small sample requirement of 10 microliters allows you to assay hard to get or expensive samples using the superior characteristics of the vapor pressure method.
Since solution concentration, or osmolality, is fundamental to all physiochemical processes in the body involving diffusion of solute or transfer of fluids through membranes, knowledge of the various body fluid osmolalities is fundamentally useful in prognosis, evaluating water/solute balance, and in monitoring I.V. therapy.
Osmolality measurements on serum or whole blood detect any departure from the narrow range of normality (270 to 290 mmol/kg) maintained in homeostasis. Abnormal blood osmolality occurs in association with shock and shock/trauma, water intoxication, anomalies in body sodium balance, increased glucose levels (ketogenic or nonketogenic diabetes) increased urea concentration (renal failure), and burns.
Clinical Applications Include:
- Emergency Room
- Burn Patients
- Trauma, head injury and shock
- Coma
- Diabetic Coma
- Prognosis
- Serum osmolality and osmolal discriminant
- Renal function
- Monitoring
- Stool analysis
- Body fluids
- Surgery
- ADH therapy
- Renal dialysis
- Post operative
- Burn Therapy
- Insulin therapy
- Fetal maturity
- Hyper/hyponatremia
- Diagnosis
- Cystic Fibrosis diagnosis by osmolality assay of sweat
- Differential diagnosis of diabetes insipidus
- Differential diagnosis of polyuria or olguria
- Quality Assurance
- Blood bank assessment of residual glycerol in final cell suspensions
- Enteral and parenteral nutrition preparations
- Physiological infusion solutions
- Monitoring infant formulas
- Reagent and standard solutions
| Vapro Pressure Osmometer Specifications Model 5520 | ||||||||||
| Sample Volume | 10 �L nominal (Larger samples or samples as small as 2 �L can be measured reliably with special procedures) | |||||||||
| Measurement Range | Typically 0 to 3200 mmol/kg @ 25� C ambient (0 to 3500 mmol/kg with extended range option) |
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| Measurement Time | 75 seconds | |||||||||
| Resolution | 1 mmol/kg | |||||||||
| Repeatability Linearity Readout | Standard deviation = 2 mmol/kg, 2%of reading from 100 to 2000 mmol/kg, 10 X 6.8 cm LCD | |||||||||
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Operating Temperature |
15 to 37� C ambient (instrument should be at stable temperature before calibrating) | |||||||||
| Calibration | Automatic using Opti-mole™ osmolality standards (non-battery memory backup system) | |||||||||
| Serial Output | RS-232 (ASCII format) | |||||||||
Electrical
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| Height | 17 cm (6.6") | |||||||||
| Width | 29 cm (11.5") | |||||||||
| Depth | 34 cm (13.5") | |||||||||
| Weight | 3.6 kg (8 lbs) | |||||||||
| Buyer's Specifications The osmometer shall be a Wescor Model 5520 Vapor Pressure Osmometer and shall operate on the vapor pressure depression principle. The osmometer shall be capable of routine osmolality determinations on sample volumes of 2-10 microliters and shall perform the measurement automatically once the sample has been loaded. The osmometer shall be capable of routine osmolality determinations on whole blood, viscous samples and tissue specimens. The osmometer shall consume no more than 30 watts of electrical power and shall weigh less than 4 kg. |
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