Thermal Analysis
Adorjan Aszalos in 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.
Drug Substance and Excipient Characterization
Dilip M. Parikh in Handbook of Pharmaceutical Granulation Technology, 2021
In this method, the polymorphs are identified by their thermal behaviors. The change in energy or related property of the polymorph as it undergoes a transformation when heated is recorded as a thermogram (Figure 3.9). The thermogram consists of characteristic peaks, including melting point (Tm) and glass transition temperature (Tg). The peaks pointing downward indicate endothermic changes, such as melting, sublimation, and desolvation. The different polymorphs of material will exhibit different thermograms, which allow them to be identified. Differential scanning calorimetry (DSC) and differential thermal analysis are two methods of thermal analyses that are commonly used. The sample is sealed in an aluminum pan and placed inside the test chamber where it is subjected to different heating rates. In DSC, the change in heat energy resulting from the crystalline transformation is recorded as a function of temperature. In the differential thermal analysis, the energy is expressed by differential temperature (sample vs. inert substance).
Nanoparticle Synthesis and Administration Routes for Antiviral Uses
Devarajan Thangadurai, Saher Islam, Charles Oluwaseun Adetunji in Viral and Antiviral Nanomaterials, 2022
Thermal analysis, composed by differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermogravimetric analysis (TGA), are able to analyze several physical (crystallization or fusion) and chemical (oxidation or decomposition) aspects in relation to the compounds present in the formulations in function of the temperature. DSC determines the difference in thermal energy absorption between the sample to be analyzed and some standard compound or reference under the influence of a constant increase in temperature at a constant rate (Ibarra-Molero et al. 2016; Knopp et al. 2016; Durowoju et al. 2017). DTA and TGA informs loss of mass, phase transitions, as well as degradation of the compounds present in the formulation (Juarez-Perez et al. 2016; Cai et al. 2018; Kaya et al. 2020).
Preparation, characterization and dynamical mechanical properties of dextran-coated iron oxide nanoparticles (DIONPs)
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Hatice Kaplan Can, Serap Kavlak, Shahed ParviziKhosroshahi, Ali Güner
This work expresses the effort to understand the preparation of DIONPs in situ co-precipitation methods and nature of the interaction mechanism and thermal stability of dextran with iron oxide. This study describes the synthesis route of DIONPs and physical properties characterization by using XRD and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The thermal analysis was examined by differential scanning calorimetry (DSC), differential thermal analysis (DTA) and thermal gravimetric analysis (TGA). Dynamical mechanical properties of magnetic dextran nanoparticles were analysed by dynamic mechanical analysis (DMA).
Silver nanoparticles obtained from Brazilian pepper extracts with synergistic anti-microbial effect: production, characterization, hydrogel formulation, cell viability, and in vitro efficacy
Published in Pharmaceutical Development and Technology, 2021
Daniele M. de Oliveira, Diego B. Menezes, Lucas R. Andrade, Felipe da C. Lima, Luciana Hollanda, Aleksandra Zielinska, Elena Sanchez-Lopez, Eliana B. Souto, Patrícia Severino
The dispersion of AgNPs in the freshly prepared sodium alginate/gelatin hydrogels did not result in particle aggregation nor gelation. To study the thermal stability of the developed semi-solid formulation, thermogravimetry (TG/DTG) analyses were carried out before (pure hydrogel) and after (AgNPs-loaded hydrogel) dispersing AgNPs into the hydrogel (3 wt. %). For thermogravimetric analysis, the samples were subjected to a constant temperature variation while the mass variation was monitored. Peak temperature and weight loss are shown in Table 4. Figure 4 shows the respective thermogravimetric and differential thermal analysis profiles.
Loading, release profile and accelerated stability assessment of monoterpenes-loaded solid lipid nanoparticles (SLN)
Published in Pharmaceutical Development and Technology, 2020
Aleksandra Zielińska, Nuno R. Ferreira, Agnieszka Feliczak-Guzik, Izabela Nowak, Eliana B. Souto
Differential scanning calorimetry (DSC) is thermoanalytical technique, which measures the differences between the heat flows from the sample and reference as a function of temperature or time. These differences in heat flow arise when a sample absorbs or releases heat due to thermal effects such as melting, crystallization, chemical reactions, polymorphic transitions or vaporization process. The heat exchanges during controlled temperature programs provide to obtain the information on the structural properties of the sample (Bunjes and Unruh 2007). The basic types of DSC can be distinguished (Klančnik et al. 2010), namely the heat flux DSC, the power compensation DSC, and the hyper DSC. In this work, a differential scanning (DSC) was used to determinate the temperatures of the phase transitions like melting point, solidification onset, re-crystallization onset or evaporation temperature (Klančnik et al. 2010). By differential thermal analysis (DTA), the curves could record the transformations where the heat is either absorbed or released. Applying this technique was helpful for better understanding of given results by other methods, such as X-ray diffraction, chemical analysis or microscopy (Omwoyo et al. 2014). Figure 6 presents the comparison of obtained results during cooling process of DSC for all of analyzed monoterpenes encapsulated into SLN, as well as for empty-SLN refers to solid lipid nanoparticles that do not contain drug, while Figure 7 shows the results during heating process for the same samples. DSC analysis was performed to determine the crystallinity of drug in nanoparticles, because this process may greatly influences on the solubility and dissolution characteristics of the drug (Omwoyo et al. 2014). To describe the crystallinity state of the monoterpenes-loaded SLN, samples were gradually heated and then cooled in the DSC instrument to enable the comparison of DSC thermograms.