Thermal analysis is an
analytical method to study the relationship between physical and
chemical changes and temperature of materials. This article summarizes
application of thermal analysis technology in research field of
traditional Chinese medicine.
1. Classification of Methods of Thermal Analysis Technology
There are various types of thermal analysis methods, among which differential thermal analysis (DTA), thermogravimetry (TG) and differential scanning calorimetry (DSC) are the most widely used in study of traditional Chinese medicine, and selection of thermal analysis samples pan is relatively stable.
1.1 Differential Thermal Analysis (DTA)
The method of measuring the temperature difference between the test object and the reference object is called Differential Thermal Analysis (DTA).
1.2 Differential Scanning Calorimetry (DSC)
DSC is heating up the sample and reference material, and measuring their difference of heat absorbed or released during the heating process.
1.3 Thermogravimetric (TG)
TG is plotting a thermogravimetric (TG) curve with temperature as the abscissa and weight loss percentage as the ordinate by measuring the weight change of the measured object during heating process.
2. Application of Thermal Analysis in Identification of Traditional Chinese Medicine
Traditional Chinese medicine is rich in medicinal resources, many kinds of medicinal materials are similar in shape, and thermal analysis has achieved good results in the field of identification.
2.1 Different families and genera of medicinal materials
Some Chinese herbal medicines included in the pharmacopoeia come from different families and genus, or different origins, it’s not easy to distinguish because of their similar appearance. The same DSC Sample Pans was used to measure TG of pearl powder samples and talcum powder, they can be identified due to different weight loss. By DSC of pearl powder and shell powder in Thermal Analyzers Sample Pan at a temperature range of 100~500℃, the result of multi-scan showed that enthalpy values of pearl powder are above 40J/g, while that of shell powder are below 40J/g, therefore pearl powder could be identified.
2.2 The medicinal materials belong to the same family
In recent years, increasing attention has been paid to application of thermal analysis in identification of traditional Chinese medicines from the same family of plants. Popularization and application of thermal analysis provides a new method to identify medicinal plants.
2.3 Different origins of the same medicinal material
Origin of Chinese medicine affects the quality. Application of thermal analysis can reveal the characteristics of medicinal materials from different origins, which can quickly evaluate their quality and effective utilization.
2.4 Processed products and artificial products, resins, etc.
TG-DTA spectra of native and calcined copper under argon atmosphere were analyzed. The experimental data showed that moisture content (44%) of native copper samples in the crucible was significantly higher than that of the calcined products (2.0%), which can be used to distinguish native product from calcined product.
3. Application of thermal analysis method in traditional Chinese medicine preparation
In order to avoid interaction of active ingredients before use and influence to drug effect, thermal analysis method is used to study of pharmaceutical preparation and compound compatibility, which provides new methods to guide rational usage of prescription and control preparation composition.
4. Summary
DTA, TG and DSC are not only used to identify medicinal materials from different families, genus or origins, but also to identify processed products, artificial products and resin medicinal materials. Combined with other methods, such as infrared spectroscopy and gas chromatography, a large amount of reliable and extensive information can be obtained, which has a better application prospect for identification and analysis of traditional Chinese medicine.
1. Classification of Methods of Thermal Analysis Technology
There are various types of thermal analysis methods, among which differential thermal analysis (DTA), thermogravimetry (TG) and differential scanning calorimetry (DSC) are the most widely used in study of traditional Chinese medicine, and selection of thermal analysis samples pan is relatively stable.
1.1 Differential Thermal Analysis (DTA)
The method of measuring the temperature difference between the test object and the reference object is called Differential Thermal Analysis (DTA).
1.2 Differential Scanning Calorimetry (DSC)
DSC is heating up the sample and reference material, and measuring their difference of heat absorbed or released during the heating process.
1.3 Thermogravimetric (TG)
TG is plotting a thermogravimetric (TG) curve with temperature as the abscissa and weight loss percentage as the ordinate by measuring the weight change of the measured object during heating process.
2. Application of Thermal Analysis in Identification of Traditional Chinese Medicine
Traditional Chinese medicine is rich in medicinal resources, many kinds of medicinal materials are similar in shape, and thermal analysis has achieved good results in the field of identification.
2.1 Different families and genera of medicinal materials
Some Chinese herbal medicines included in the pharmacopoeia come from different families and genus, or different origins, it’s not easy to distinguish because of their similar appearance. The same DSC Sample Pans was used to measure TG of pearl powder samples and talcum powder, they can be identified due to different weight loss. By DSC of pearl powder and shell powder in Thermal Analyzers Sample Pan at a temperature range of 100~500℃, the result of multi-scan showed that enthalpy values of pearl powder are above 40J/g, while that of shell powder are below 40J/g, therefore pearl powder could be identified.
2.2 The medicinal materials belong to the same family
In recent years, increasing attention has been paid to application of thermal analysis in identification of traditional Chinese medicines from the same family of plants. Popularization and application of thermal analysis provides a new method to identify medicinal plants.
2.3 Different origins of the same medicinal material
Origin of Chinese medicine affects the quality. Application of thermal analysis can reveal the characteristics of medicinal materials from different origins, which can quickly evaluate their quality and effective utilization.
2.4 Processed products and artificial products, resins, etc.
TG-DTA spectra of native and calcined copper under argon atmosphere were analyzed. The experimental data showed that moisture content (44%) of native copper samples in the crucible was significantly higher than that of the calcined products (2.0%), which can be used to distinguish native product from calcined product.
3. Application of thermal analysis method in traditional Chinese medicine preparation
In order to avoid interaction of active ingredients before use and influence to drug effect, thermal analysis method is used to study of pharmaceutical preparation and compound compatibility, which provides new methods to guide rational usage of prescription and control preparation composition.
4. Summary
DTA, TG and DSC are not only used to identify medicinal materials from different families, genus or origins, but also to identify processed products, artificial products and resin medicinal materials. Combined with other methods, such as infrared spectroscopy and gas chromatography, a large amount of reliable and extensive information can be obtained, which has a better application prospect for identification and analysis of traditional Chinese medicine.
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