Thermal Properties Analysis Instruments: DSC, TGA, STA, and TMA

A: DSC (Differential Scanning Calorimetry) measures the heat flow to or from a sample as it is heated or cooled — detecting thermal events that involve energy exchange, such as melting, crystallization, glass transition, and phase transformation, even when no mass change occurs. TGA (Thermogravimetric Analysis) measures sample mass as a function of temperature — detecting events involving mass loss or gain, such as moisture evaporation, solvent release, decomposition, and oxidation. Simultaneous Thermal Analysis (STA) runs both techniques on the same sample in one experiment, allowing direct correlation of mass events and thermal events without sample-to-sample variability.

A: A Simultaneous Thermal Analyzer (STA) combines TGA and DSC — or TGA and DTA — in a single instrument, measuring mass change and heat flow simultaneously on the same sample in the same run. The key advantage over running separate TGA and DSC experiments is that every thermal event and every mass loss event are measured under identical conditions, on the same sample, at the same time. This eliminates the ambiguity of comparing data from two separate samples and directly resolves whether a thermal event involves mass loss (TGA responds), a purely calorimetric transition (DSC responds without TGA), or both. AMI’s STA Series uses a true hang-down balance with 0.1 μg readability and operates from −40°C to 650°C, ambient to 1200°C, or ambient to 1500°C.

A: DSC is the primary thermal analysis technique for pharmaceutical materials — measuring melting point, polymorphic form identification, purity by melting point depression, glass transition temperature of amorphous drug forms, and enthalpy of fusion. The AMI DSC 600 with high-sensitivity sensor is suited to these measurements. TGA complements DSC by quantifying residual solvents, moisture content, and decomposition onset — critical data for ICH Q1A stability studies. For materials that show both heat flow and mass change events (such as hydrates losing water of crystallization), the STA provides the most complete picture in a single experiment.

A: AMI’s thermal properties analysis instruments cover a wide temperature range. The DSC 600 covers standard thermal analysis temperatures with optional LN₂ sub-ambient cooling. The DSC 1200 and DSC 1500 extend calorimetry to 1200°C and 1500°C respectively for high-temperature materials. The TGA Series covers ambient to 1000°C, 1200°C, or 1500°C. The STA Series covers −40°C to 650°C (with sub-ambient system), ambient to 1200°C, or ambient to 1500°C. The TMA 800 covers ambient to 800°C with optional sub-ambient capability to −80°C using the RCS cooling system.

A: Yes. AMI’s TGA and STA instruments support coupling with mass spectrometry (MS) or Fourier Transform Infrared Spectroscopy (FTIR) for evolved gas analysis (EGA). This TGA-MS or TGA-FTIR configuration identifies the gases released during thermal decomposition — providing molecular-level identification of decomposition products, residual solvents, and volatile components alongside the TGA mass loss data. The STA 4-Gas Selector system also enables programmable gas switching during analysis, allowing experiments under different atmospheres within a single temperature program.

A: Match the instrument to what property governs your material’s performance or quality. Use DSC when you need to characterize heat-related transitions — melting, Tg, crystallinity, purity, curing, or phase transformations. Use TGA when you need to quantify mass changes with temperature — moisture, solvent content, decomposition, filler loading, or ash. Use STA when both types of information are needed simultaneously on the same sample — it provides more complete data with less experimental time. Use TMA when dimensional change with temperature is the critical property — CTE, Tg by mechanical change, softening point, or film/coating deformation. For complex or unfamiliar materials, STA is typically the best starting point because it captures the most information per experiment. t