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Thermal Analysis
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Another mode of differential thermal analysis exists that is referred to as differential scanning calorimetry (Figure 2). With some instrumental designs, this terminology refers to refinements in the design of DTA systems so that data can be obtained in more quantitative and reproducible ways. The earlier use of the DSC terminology, which is still in use, referred to a system in which the calories required to maintain a constant temperature difference between a sample and a reference were directly measured. This was accomplished by measuring the amperage flowing into small heaters next to the sample, the flow of amperes so controlled as to be proportional to developing temperature differences. In this manner a direct measurement of the calories involved was obtained.
Thermal Analysis of Herbal Drugs
Published in Ravindra Kumar Pandey, Shiv Shankar Shukla, Amber Vyas, Vishal Jain, Parag Jain, Shailendra Saraf, Fingerprinting Analysis and Quality Control Methods of Herbal Medicines, 2018
Ravindra Kumar Pandey, Shiv Shankar Shukla, Amber Vyas, Vishal Jain, Parag Jain, Shailendra Saraf
In Differential Thermal Analysis, the temperature difference that develops between a sample and an inert reference material is measured when both are subjected to identical heat treatments. The related technique of Differential Scanning Calorimetry relies on differences in energy required to maintain the sample and reference at an identical temperature. The analytical method for recording the difference in temperature (T) of a substance and an inert reference material as a function of temperature or time and any transformation change in specific heat or an enthalpy of transition can be detected by DTA (Brandão et al., 2016).
Experimental Strategies
Published in Clive R. Bagshaw, Biomolecular Kinetics, 2017
Another form of calorimetry, differential scanning calorimetry, is also widely used to screen for ligand–protein interactions [360]. Here, a protein is slowly heated and the temperature at which it denatures is characterized by a peak in the heat absorption. Ligand binding usually increases the melting temperature, and hence, the shift in melting temperature with increasing ligand concentration can be used to estimate the Kd. The technique has two problems. The Kd refers to that at the melting temperature, which is likely to be higher than that of interest for the problem under study. More significantly, the observed melting temperature often depends on the rate of heating, indicating that the system is not in true equilibrium and the Kd is not rigorously defined. However, the method does allow very high-affinity interactions to be investigated [361].
Development and validation of HPLC method for simultaneous estimation of erlotinib and niclosamide from liposomes optimized by screening design
Published in Journal of Liposome Research, 2023
Amruta Prabhakar Padakanti, Sachin Dattaram Pawar, Pramod Kumar, Naveen Chella
Estimating the drug–drug and drug–excipient interactions is a critical preformulation analysis that has a vital role in formulation development. Differential scanning calorimetry is an invaluable technique to identify the purity of the drugs and possible drug–drug and drug–excipient interactions. Figure 3 shows the sharp melting endotherm at 227 °C and 229 °C in the pure NCM (Al-Hadiya 2005) and ERL (Abdelgalil et al. 2020) DSC thermal profiles; these are similar to the values reported in the literature respectively. The broad endotherm at 90 to 100 °C in NCM was due to the loss of water molecules from NCM., and the sharp melting curve indicates that drugs were pure and crystalline. At the same time, the mixture of NCM and ERL in a 1:1 ratio showed a broad endotherm at 80 to 90 °C, corresponding to water loss from NCM and two broad melting endotherms with a shift in temperature. The absence of new peaks and the presence of two peaks of NCM and ERL indicate no interactions between them. Also, pure phosphatidylcholine (PC) and cholesterol has shown endothermic peak at 232 °C and 146 °C, respectively (Song et al. 2021). The presence of all these peaks in the physical mixture of NCM, ERL, cholesterol, and PC indicates that these all are compatible without any interactions (Figure 3). These results are correlated to the results obtained in ATR-IR analysis.
A drift on liposomes to proliposomes: recent advances and promising approaches
Published in Journal of Liposome Research, 2022
Neha Dhiman, Jayrajsinh Sarvaiya, Poorti Mohindroo
Differential scanning calorimetry (DSC) is a popular thermal analytical technique for obtaining detailed information on a substance's physical and energetic properties. It allows researchers to investigate melting, crystalline, and mesomorphic transition temperatures, as well as the enthalpy and entropy changes that go along with them, as well as the characterization of glass transition effects (Clas et al.1999, Schick 2009, Pirooznia et al.2012). DSC also aids in the identification of the thermal behavior of solvents used in liposome dispersions and dispersions containing mannitol. Hence provides a valuable tool for the detection of changes within the physical state of water in liposome dispersions during freezing. Furthermore, DSC can be used to investigate the interaction of the formulation ingredients in proliposome powder (Talsma et al.1991).
Amorphization and modified release of ibuprofen by post-synthetic and solvent-free loading into tailored silica aerogels
Published in Drug Delivery, 2022
Ajmal Zarinwall, Viktor Maurer, Jennifer Pierick, Victor Marcus Oldhues, Julian Cedric Porsiel, Jan Henrik Finke, Georg Garnweitner
Thermal analyses were further performed by dynamic differential scanning calorimetry (DSC). Therefore, the powdered samples were loaded in an aluminum crucible with a perforated lid and subjected to a heating/cooling profile (20 °C to 100 °C) in a DSC apparatus (DSC 3+, Mettler Toledo GmbH, Columbus, Ohio, USA) with a heating rate of 10 °C/min under a nitrogen purge gas flow. Based on the so determined enthalpy of fusion of plain (Hibu) and embedded ibuprofen (Hsample), the content of amorphized (A%) ibuprofen within the formulation was calculated by further taking into account the respective mass fraction of ibuprofen (ωibu) (Patel et al., 2014):