Cp=K(Cp)AmpMHFAmpMHR Where K (Cp) is the heat capacity constant, AmpMHF and AmpMHR are the amplitudes of modulated heat flow and heat rate, respectively. K(Cp)=Cp,theoreticalCp,measured

However, for precise heat capacity measurements several points like the thickness of the sample bed in sample pan, the thermal contact resistance between the sample and PD98059 supplier the sample pan, and the thermal contact resistance between the sample pan and the base plate of the apparatus have to be considered in order to get reliable results. IGC is a vapor sorption technique in which the powder is packed in a column and known vapors (usually at infinite dilution in a carrier gas) are injected. From the retention times of the probes it is possible to assess the surface nature of the material in the column.23 IGC is a highly sensitive technique and has been used to determine the specific energies

of adsorption of polar probes DGSP A, which can Decitabine datasheet then be used to calculate the basic/acidic parameter ratio KD/KA. This parameter describes the acidic and basic nature of the powder surface and can be correlated with crystallinity.24 Values of KD/KA of greater than 1 mean a basic nature on the surface of a solid and values of less than 1 mean an acidic nature. Water sorption or gravimetric techniques have been extensively used in the study of many amorphous and partially amorphous powders.24 It is a useful method for standardizing the amorphous content either as a single component or in combination.21 Dynamic vapor sorption (DVS) is based on the concept of exploitation of crystallization of amorphous materials with changes in humidity,

with consequent expulsion of water. Extent of water sorption and desorption is related to the amorphous content of the sample. DVS works simply by detecting the crystallization response for the amorphous material, with little or no interfering response from the crystalline component.25 The gravimetric studies are usually conducted in a humidity-controlled microbalance system. The sample is loaded on one side of a very single or twin pan balance, and the system is programmed for measurement of sorption and desorption at particular humidity and temperature. However, the moisture sorption isotherms cannot be used as such for the quantification of amorphous content as the moisture absorbed by the amorphous regions as well as that adsorbed onto the surface will contribute to the total water adsorbed by the sample. Dissolution calorimetry measures the energy of dissolution, which is dependent on the crystallinity of the sample. Usually, dissolution of crystalline material is endothermic, whereas dissolution of amorphous material is exothermic. Confocal Raman spectroscopy is used to measure the homogeneity of the solid mixture.