What is the sensitivity of TG? How small a mass change can it detect?

TG Sensitivity and Mass Change Detection Capabilities

TG sensitivity is a practical detection question, not a fixed balance specification. A planning reference such as 0.1 micrograms (μg) or 0.001% of a standard 10-milligram sample is illustrative; usable mass-change detection depends on balance noise, drift, buoyancy, gas flow, vibration, sample homogeneity, heating rate, and the event size. For an RFQ, provide material, process, sample mass and form, atmosphere, temperature program, expected change, acceptance criterion, and report fields. Verify baseline and reference performance, then report uncertainty and disposition.

Factors Influencing Practical Detection Limits

Instrumental and Environmental Considerations

Balance noise and environmental control matter when testing ceramic or Plastics. Control vibration, temperature, static, gas flow, buoyancy, pan position, and baseline drift; choose the heating rate and sample mass from the expected event. Verify a stable baseline and reference response before treating a small mass change as real.

Sample-Specific Considerations

For metal powders from Powder Bed Fusion or polymers from Material Extrusion, particle or filament homogeneity affects signal-to-noise. Dry or condition the sample as specified, record mass and atmosphere, distinguish moisture loss from decomposition, and correlate the result with the final material state. Select a complementary test when TG cannot identify the evolved species, then verify and record the conclusion.

Application-Specific Detection Capabilities

High-Sensitivity Applications

TG can screen moisture or residual solvent in Aluminum Alloys powders or Resins when the method, mass, atmosphere, and calibration support the question. For Aerospace and Aviation work, define the acceptance limit and final state; a detected mass change does not by itself identify a contaminant or establish service qualification. Confirm with a reference or complementary analysis and record disposition.

Comparison with Complementary Techniques

TG reports mass change but does not identify the gas or chemical mechanism. For Stainless Steel or Titanium Alloy materials, pair the curve with evolved-gas analysis, spectroscopy, OES, SEM/EDS, or another method selected from the acceptance question. Preserve the sample state, verify calibration, and state whether the result supports screening, development, or release.

Interpreting Small Mass Changes

TG sensitivity is affected by balance performance, buoyancy correction, baseline drift, sample mass, gas flow, pan, heating rate, and the magnitude and speed of the event. A nominal balance sensitivity is not the same as a validated quantitation limit for a particular material and program.

Define the minimum mass change that matters, expected transition temperature, sample mass, atmosphere, and reporting units before testing. The report should show the baseline treatment, calibration or verification, blank behavior, repeatability, and any interference that makes a small change unsuitable for a release decision.

When a small event controls a debinding or oxidation decision, use a reference or repeat program to distinguish a real mass change from baseline drift, buoyancy, pan effects, or gas switching. State the reporting threshold and uncertainty rather than presenting every visible movement in the TG trace as a material transition.

For a process window, repeatability is often more important than a visually clean single curve. Use matched sample mass, pan, gas flow, heating rate, and baseline treatment for comparison runs. If the event is small relative to drift or buoyancy, report it as below the validated decision capability rather than assigning a precise onset temperature. A second method or a larger representative sample may be needed.

When the required decision concerns a small mass loss or weak thermal event, include replicate runs and a control material in the plan. Report onset, peak, end temperature, mass change, and uncertainty using the same baseline convention. Do not compare onset temperatures from programs with different heating rates or atmospheres without explaining the difference.

For powder, binder, or ceramic work, state whether the reported mass change is normalized to dry mass, received mass, or another basis. A dry-mass correction can change the apparent percentage loss, so the starting condition, balance correction, pan, and blank treatment should be visible in the report.

TG sensitivity is a property of the complete balance, pan, baseline, atmosphere, sample mass, heating program, and data-processing method. Ask for the noise or baseline check, mass range, calibration status, and reporting rule for a small change. A visible mass shift may still be below a validated decision limit, while buoyancy or moisture loss can look like a process event. Report the measured change with uncertainty or limitation.

A small mass change should be reported with the baseline, noise, buoyancy correction, atmosphere, heating rate, sample mass, and uncertainty or limitation. Moisture loss, binder burnout, oxidation, and pan effects can produce different signals. If the result controls a process window, confirm the event with a repeat run or complementary measurement before changing the production route.