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Thermal gravimetric analysis (TGA)

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This page contains a collection of information how to reference analytical data. We provide this page to describe the preferred formatting of analytical evaluations in the Chemotion repository. The given preferences follow standards of journals/publishers and other stakeholders wherever we could find them. If you have suggestions and comments: please let us know or provide your ideas via the issue tracking option. https://github.com/ComPlat/chemotion_saurus/issues Updated: 21.11.2024

Inline notation for thermal gravimetric analysis (TGA)​

The inline notation gives a short summary of the metadata and a list of the results of the TGA measurement. The analysis of the TGA measurements should contain at least the values for T5% (Temperature at which 5% weight loss is observed), and Tmax (Temperature with the highest decomposition rate, maximum of first derivative). The latter one should be labelled with "*". The value T95% (Temperature at which 95% weight loss is observed) should further be reported if observable. Additional decompositions steps should be included if detected and listed between T5% and T95%. If there are known decomposition reasons (such as loss of water) this information should be added in brackets after the listing of the corresponding temperature. At the end, the final value of the residue should be reported in %. Normally, the process consists of an isothermal step to equilibrate the material, then a temperature ramp to the desired maximum temperature, and a final isothermal step. The process description should contain information about the starting temperature in °C, the time intervals for the isothermal steps in min, and the increasing rate of the temperature in °C/min. For each step: onset, maximum, endset, how much is lost in total If applicable, IR detection can be used to obtain more information about the decomposition products. The IR spectra should be reported according to the standardized protocol of IR.

Examples for desired formatting:​

(1) Standard example:
TGA (Pt; N2; 30 °C (3 min), 30 °C to 900 °C (10 °C/min), 900 °C (5 min)): Temp. in °C (weight loss, %) = 50 (5), 80* (30) [-EtOH], 100 (95) [-H2O].

(2) Gas loss during measurements:
TGA (Pt; N2; 30 °C (3 min), 30 °C to 900 °C (10 °C/min), 900 °C (5 min)): Temp. in °C (weight loss, %) = 283 (5) [-HCl], 300* (30), 310 (95).

(3) Sample with a residue >5%:
TGA (Pt; N2; 30 °C (3 min), 30 °C to 900 °C (10 °C/min), 900 °C (5 min)): Temp. in °C (weight loss, %) = 283 (5) [-HCl], 300* (30). Residual: 20%.

(4) Several degradation steps:
TGA (Pt; N2; 30 °C (3 min), 30 °C to 900 °C (10 °C/min), 900 °C (5 min)): Temp. in °C (weight loss, %) = 50 (5), 200 (95). First step: 78-80-83 (25). Second step: 123-130-140 (60).

Explanation:

  • Pt = support material used for the measurement (other materials are possible, e.g. Al)
  • N2 = carrier gas used in the process (other possibilities: e.g. air)
  • 30 °C (3 min), 30 °C to 900 °C (10 °C/min), 900 °C (5 min) = process description in short form
  • Temp. in °C = temperature at which a certain weight loss in percentage is recorded
  • Weight loss, % = weight loss at a certain temperature in %
  • [-H2O] = Additional information on the loss of a certain known component

Original text for the process -> summarized in the example above:
Select Gas: Gas 1 ; Equilibrate 30,00 °C; Isothermal 3,0 min; Ramp 10,00 °C/min to 900,00 °C; Equilibrate 900,00 °C; Select Gas: Gas 2 ; Isothermal 10,0 min