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Your location: Home > Related Articles > Interpretation of relevant principles of freezing point osmometer

Interpretation of relevant principles of freezing point osmometer

Author:QINSUN Released in:2023-05 Click:125

Freezing point osmometer is an instrument used to measure osmotic pressure or osmolality of crystals in solution.

In clinical medicine, dosage of serum or plasma, urine, gastric juice, cerebrospinal fluid, saliva, sweat and various plasma substitutes, injection, dialysis fluid, baby drink, electron microscope fixative, The osmotic pressure of solutions such as tissue cell culture fluid and preservation fluid.

For the study of the balance of water and salt metabolism, the evaluation of renal dysfunctions, the monitoring of diabetes, the observation of endocrine disorders ADH, the understanding of trauma, burns, shock, changes in critical surgical conditions after major surgery and artificial dialysis, follow-up of infusion therapy and pharmacological analysis of drugs (especially Chinese herbal medicines) are of great importance.

Equipment principle

The working principle of the freezing point osmometer is based on the proportional relationship between the vacuum value of the freezing point and the molar solubility of the solution.

Using a high sensitivity temperature sensing element semiconductor measuring sensor to measure the freezing point of the solution, it is achieved by converting electricity into a unit of osmotic pressure (m0sm/kg).

The test tube of the sample to be tested is placed in a semiconductor refrigerator, and antifreeze is used as a conduction medium to cool the solution in the test tube ;

Semiconductor The heat-absorbing side of the refrigerator absorbs heat from the antifreeze to cool it, and the heat-generating side is cooled by the cooling fan.

The process ofThe temperature change of the tested sample is as follows:

Freezing point refers to the temperature at which the solution changes from liquid to solid. For aqueous solution, from liquid to solid During the cooling change process;

The phenomenon that the temperature has reached the freezing point or even exceeded the freezing temperature without freezing is called \" supercooling phenomenon.

The supercooled liquid state is extremely unstable, and any disturbance can cause it to crystallize immediately and become a solid state.

When the liquid changes into a solid state, because the molecular energy suddenly changes from a high energy state to a low energy state, the excess energy will be released as heat, called \"heat of crystallization\".

Due to the existence of heat of crystallization, the temperature of the supercooled solution at thewill increase upon freezing.

The above process can be described by the following \"icing curve\".

In the figure, point A is the start of solution cooling, point B is the point of supercooling temperature, point C is the point of initial freezing temperature of the solution, segment CD is the stable phase of the freezing point temperature, segment DE Continue cooling for the solid state.

Given the linear relationship between the osmotic solubility or osmotic pressure value of a solution and the drop in its freezing point, as long as the temperature value of the point freezing temperature of the obtained solution is divided by 1.857, the osmotic pressure value of the solution can be obtained.