Monitoring thermochemical events and weight loss as a function of temperature can give valuable insight into solid form characteristics, mechanisms of polymorphic transformations, and solid-state degradation pathways. SSCI uses modern differential scanning calorimetry (DSC) and thermal gravimetric instrumentation (TGA) to analyze these properties of bulk and formulated solid products.
DSC, Modulated DSC
Differential scanning calorimetry (DSC) is one of the most widely used thermal analysis techniques for the characterization of pharmaceutical solids. Thermal events such as melting, recrystallization, decomposition, and glass transitions can be measured. Additionally, quantitative mixture analysis (i.e. determination of polymorph mixtures) can be performed. The use of modulated DSC expands the capabilities of DSC by allowing for the measurement of heat capacities and the characterization of reversible/non-reversible thermal transitions.
Melting point determination is a very important aspect of polymorph analysis in terms of stability. SSCI provides melting point determination as per the various methods outlined in the USP.
TGA and TG/IR
Thermogravimetric analysis (TGA) measures the thermally induced weight loss of a sample as a function of temperature. In conjunction with DSC and hot-stage optical microscopy, TGA provides an excellent approach to the determination of thermal properties of the pharmaceutical material. Extending the TGA technique to thermogravimetric/infrared analysis (TG/IR) provides the ability to not only measure the thermally induced weight loss, but also to chemically identify the volatile component during each weight loss step. As a volatile component is evolved from the sample in the TG furnace, it is swept into a gas-phase IR cell for spectroscopic analysis and potential chemical identification. TG/IR is an ideal technique for solvate and hydrate analysis.
Hot-Stage Optical Microscopy
Hot-stage optical microscopy is a technique that SSCI uses in conjunction with differential scanning microscopy (DSC), thermal gravimetric (TG) or thermal gravimetric/infrared (TG/IR) to characterize the thermal properties of your pharmaceutical solid. SSCI provides analysis with two different hot-stages that allow for controlled temperature experiments from -196 to 600 °C. Visual thermal events (such as melting, recrystallization, or volatilization) can be captured as video or digital images.
Isothermal microcalorimetry is a technique useful for studying a wide variety of physical and chemical processes. It can be used to evaluate excipient compatibility, amorphous content, degradation rate, relative stability of polymorphs, and any other process associated with a change in enthalpy. SSCI’s instrumentation includes specialized accessories that allow control of the relative humidity and oxygen content of the sample environment.
Solution calorimetry is used to measure the heat of solution of a solute as it dissolves in a solvent. This measurement can be used for detection and quantification of polymorphs and amorphous material, determination of the relative stability of polymorphs, and for monitoring dissolution processes. SSCI’s instrumentation includes both semi-adiabatic and isothermal solution calorimeters.