Thermal Analysis Tips

6th : What kinds of measurement errors occur in TG analysis?

To correctly interpret TG results, it is necessary to understand not only the initial mass but also the errors caused by drift originating from the instrument. In TG measurements, we typically analyze the percentage change in mass. Several factors can contribute to errors in the analysis results. One of them - the initial sample mass - was discussed in the previous article.

Another important factor is drift. Drift is sometimes referred to as an “apparent mass change.”; it is a change in mass caused by the instrument itself, rather than by the sample. Drift can be evaluated by placing empty pans, or pans filled with the same amount of alumina —one for the sample and one for the reference—into the instrument and then performing a measurement; this is called a blank measurement.

Ultimately, the sample's TG corresponds to "sample mass change + drift." Therefore, if the sample's mass change is sufficiently large compared to the drift, the error is small. However, if the sample's mass change is small and the effect of drift cannot be ignored, the amount of drift can be canceled out by subtracting the blank measurement data from the sample's measurement data. This correction operation can be easily performed in the software via:
[Analysis] → [Baseline Correction] → [Blank Correction]