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Determining the freezing point of pharmaceutical solution by differential scanning calorimetry technology (CAT#: STEM-PPA-0165-LJX)

Introduction

The osmotic pressure needs to be controlled with injectable drug solutions. When the osmotic pressure is too low, hemolysis symptoms may occur, and the irritating effect of intramuscular injection will affect the full absorption of the drug. Therefore, the reagent should be configured according to the actual situation, and the drug dosage should be appropriately adjusted to control osmotic pressure and ensure the standardized and safe production of drugs. When the composition or molecular weight of the injected drug solution is unknown, its freezing point can be determined, and the osmotic pressure of the drug solution can be obtained by the Raoult freezing point principle.




Principle

When the physical properties of a substance change (such as crystallization, melting or crystal transformation, etc.) or a chemical reaction occurs, it is often accompanied by changes in thermodynamic properties such as enthalpy, specific heat, and thermal conductivity.
Differential scanning calorimetry (DSC) is to characterize the physical or chemical change process by measuring the change of the thermodynamic properties of substances. It is a thermal analysis method to measure the relationship between the power difference of the sample and the reference substance and the temperature under the condition of programmed temperature control.
Differential scanning calorimetry can easily achieve programmed temperature rise and temperature drop. The rate of heating and cooling can be set at will in a wide range, and the crystallization and melting process of the sample can be clearly displayed through the heat flow curve, so it is often used to determine the melting and crystallization temperature of various samples.

Applications

For determining the freezing point of liquid

Procedure

1. Place the sample in the differential scanning calorimeter
2. Cooling: slowly add liquid nitrogen to the cooling tank to reduce the furnace temperature and fully freeze the sample
3. Heating up: take off the cooling tank, cover the outer cover of the furnace and the insulation cover, and heat up at a speed of 10℃/min
4. Stop the experiment after the sample is completely melted and the DSC heat flow curve returns to the baseline level

Materials

• Sample Type:
Pharmaceutical solution

Notes

The experiment should be repeated 3-5 times to ensure the accuracy of the results.