Thermogravimetric Analysis (TGA) in Drug Development: Learn Easily with 7 FAQs and 3 Case Studies

Thermogravimetric Analysis (TGA) is a powerful analytical technique widely used in pharmaceutical research, formulation development, and quality control. It helps scientists understand how a drug substance or excipient behaves when exposed to heat.

This article explains TGA in simple terms, its principle, applications, data interpretation, FAQs, and real-world case studies.

What is Thermogravimetric Analysis (TGA)?

Thermogravimetric Analysis (TGA) is an analytical technique that measures the change in mass of a material as a function of temperature or time under controlled atmospheric conditions.

In pharmaceutical development, TGA is mainly used to:

• Evaluate thermal stability
• Determine loss on drying (LOD)
• Study decomposition behaviour
• Analyzethe composition of materials

Related: Pharmaceutical Analysis

Principle of Thermogravimetric Analysis

In TGA, a small amount of sample (usually a few milligrams) is placed on a highly sensitive microbalance. The sample is heated or cooled at a controlled rate in a furnace while its weight change is continuously recorded.

The resulting data is plotted as:

• Weight (%) vs Temperature
• Weight (%) vs Time

This plot is known as the TGA curve.

Key Components of a TGA Instrument

A typical TGA instrument consists of:

1. High-Precision Balance

Measures minute changes in sample mass with high sensitivity.

2. Furnace / Heater

Provides controlled heating or cooling with programmable temperature rates.

3. Sample Holder (Pan)

Usually made of platinum or alumina to avoid interference.

4. Gas Flow System

Allows analysis under different atmospheres such as:

• Nitrogen (inert)
• Oxygen
• Air

Applications of TGA in Pharmaceuticals

Thermogravimetric Analysis is used for multiple pharmaceutical applications, including:

• Loss on Drying (LOD) determination during raw material qualification
• Thermal stability testing of APIs and excipients
• Composition analysis (moisture, solvents, additives)
• Decomposition mechanism studies
• Quantification of organic and inorganic content
• Polymer and excipient characterisation
• Stability studies for formulation development

TGA Data Interpretation

1. TGA Curve

The main output shows mass change with temperature.

Key features include:

• Weight loss steps → evaporation or degradation
• Plateaus → thermal stability regions
• Final residual mass → inorganic or ash content

2. DTG Curve (Derivative Thermogravimetry)

• Shows the rate of weight loss
• Peaks indicate temperatures of maximum decomposition rate
• Helps distinguish overlapping degradation events

3 Practical Case Studies of TGA

Case Study 1: Polymer Decomposition

A pharmaceutical polymer shows significant weight loss between 250–350°C, indicating degradation of the polymer backbone.

Case Study 2: Inorganic Filler Detection

After complete decomposition of organic material, a residual mass remains, confirming the presence of inorganic fillers like silica.

Case Study 3: Moisture Content Analysis

An API exhibits early weight loss below 120°C, confirming moisture content and helping establish drying conditions.

7 Frequently Asked Questions (FAQs) on TGA

1. Why is TGA important in drug development?

TGA helps assess thermal stability, moisture content, and composition—critical for formulation and storage decisions.

2. What sample size is used in TGA?

Typically 5–20 mg, depending on material and instrument sensitivity.

3. What atmosphere is used in TGA?

Commonly nitrogen (inert), air, or oxygen, depending on study objectives.

4. Can TGA replace LOD testing?

TGA provides more detailed thermal information but is often used in addition to, not instead of, LOD tests.

5. What is DTG used for?

DTG helps identify the exact temperature at which maximum mass loss occurs.

6. Is TGA destructive?

Yes, TGA is a destructive technique since the sample is heated until decomposition.

7. Which industries use TGA?

Pharmaceuticals, polymers, chemicals, materials science, and food industries.

Conclusion

Thermogravimetric Analysis (TGA) is a versatile and essential analytical tool in pharmaceutical development. It provides valuable insights into thermal stability, moisture content, decomposition behaviour, and material composition, supporting better formulation design and quality control.

For further learning, explore related analytical techniques such as:

• HPLC-MS
• GC-MS
• DSC (Differential Scanning Calorimetry

Further reading:

Thermogravimetric analysis