ABSTRACT
<p><b>OBJECTIVE</b>To determine the pyrolysis characteristics of calcined and processed calamine, qualitatively and quantitatively compare the contents of related elements, morphology and functional groups of the pyrolysis products dried at different heating temperatures and explore the critical temperature and the optimal drying temperature for the process of calamine with Huanglian Decoction (HLD, ) and San Huang Decoction (SHD, ).</p><p><b>METHODS</b>Pyrolysis products were prepared by programmable and constantly heating the calcined and processed calamine to or at different heating temperatures. Thermogravimetry (TG) was used to test their pyrolysis characteristics. Fourier transform infrared spectroscopy and scanning electron microscopeenergy dispersive spectrometer were used to determine their morphology, functional groups and element contents. Page model was used to investigate the constant drying kinetics of processed calamine.</p><p><b>RESULTS</b>The adding of HLD or SHD to calcined calamine (CC) can slow its weight loss in drying pyrolysis process. The temperature ranges where HLD and SHD can affect its weight loss were 65-150 °C and 74-180 °C, respectively. The drying temperature was optimized as 90 °C. The drying kinetic for the processed calamine fits Page model shows good linearity.</p><p><b>CONCLUSIONS</b>Conclusions: The critical temperature and the optimal drying temperature where HLD and SHD can affect the weight loss rate in the process of calamine were explored using the theories and methods of both biophysical chemistry and processing of Chinese materia medica. This work provides a good example for the study of the process of other Chinese medicines using modern analytical techniques.</p>
ABSTRACT
AIM@#The aim of the work is to study the pyrolysis characteristics of radix rhizoma rhei, cortex moudan radicis, and radix sanguisorbae in an inert atmosphere of argon (Ar), and to investigate the mechanism of the carbonizing process of the three traditional Chinese herbs.@*METHODS@#The pyrolysis characteristics of the crude materials and their extracts were studied by thermogravimetry-mass spectrometry (TG-MS) in a carrier gas of argon, coupled with Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM) methods. Correlation of the pyrolysis behaviors with the carbonizing process by stir-frying of traditional Chinese medicines was made.@*RESULTS@#Within the temperature range of 200-300 °C, which is the testing range for the study of the carbonizing process of Chinese herbs, the temperatures indicated by the maximum weight loss rate peak of the above three extracts were taken as the upper-limit temperatures of the carbonizing process of the herbs, and which were 200, 240 and 247 °C for radix rhizoma rhei, cortex moudan radicis, and radix Sanguisorbae, respectively. The ion monitoring signal peaks detected by the TG-MS method corresponded with reports that the level of chemical components of traditional Chinese medicinal materials would decrease after the carbonizing process. It was confirmed by Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM) methods that better results of "medicinal property preservation" could be obtained by heating at 200 °C for radix rhizoma rhei, at about 250 °C for cortex moudan radicis, and radix sanguisorbae, as the relative intensity values of the common peaks were among the middle of their three carbonized samples by programmed heating.@*CONCLUSION@#The upper-limit temperatures of the carbonizing process for radix rhizoma rhei, cortex moudan radicis and radix sanguisorbae were 200, 240 and 247 °C respectively. It is feasible to research the mechanism and technology of the carbonizing process of traditional Chinese medicinal materials using thermogravimetry, Fourier transform infrared spectrometry, and scanning electron microscopy methods.
Subject(s)
Chemistry, Pharmaceutical , Methods , Drug Stability , Drugs, Chinese Herbal , Chemistry , Hot Temperature , Mass Spectrometry , Rheum , Chemistry , Rhizome , Sanguisorba , ChemistryABSTRACT
Thermogravimetry (TG), TG-MS, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM)-energy dispersive spectrometer(EDS) were adopted to investigate the pyrolysis characteristics of calamina. According to the findings of the qualitative and quantitative studies on the changes in the content of relevant elements, the whole shape, the functional groups, and the volatile components of calamina before and after being pyrolyzed, the 200-360, 580-750 degrees C were two sensitive temperature ranges related to the changes in effective component during calamina processing. Thermal weight loss was observed for ZnCO3, Zn(OH)2 and ZnCO3-2Zn(OH)2-H2O under 200-360 degrees C and for CaCO3 under 580-750 degrees C. The results of studies on chemical reaction kinetics showed good linear relations. This experiment integrated relevant methods and theories of physical chemistry and science of traditional Chinese medicine processing, and interpretes calamina processing techniques and mechanism, in order to provide a good example for modem studies on other traditional Chinese medicine processing.