Author
John Arthur
Product Manager
PerkinElmer, Brandon Office Park, 530 – 540 Springvale Road,
Glen Waverley, VIC, 3150, Melbourne, Australia
TGA and STA Calibration - Guaranteeing Reliable Thermal Analysis Data
For the Pyris 1 TGA and STA 6000 the calibration should remain unchanged for some time, provided that there are no changes in the instrument's operating conditions. Even when the system is shut off, the calibration values are stored so that the next time the instrument is turned on, it will still be calibrated. Some of the conditions that could change either the temperature or the weight calibration and require recalibration are
- If the operating temperature range of your experiments changes, recalibration may be necessary. Check the temperature calibration in the range of interest to determine if the current calibration is still valid.
- If the purge gas type or purge gas flow is changed, the calibration should be checked for highest accuracy.
- If a new furnace is installed, the temperature calibration should be checked.
- If a new thermocouple is installed or if the position of the thermocouple changes, you should perform the temperature calibration again.
- If the analyzer is moved or releveled, you should perform the weight calibration again.
- If the hangdown wire is changed, you should perform a realignment of the gripper and recalibrate weight.
The calibration routines that need to be performed for the Pyris 1 TGA and STA 6000 are shown below in the table:
|
| Calibration/Adjustment |
Pyris1TGA |
STA 6000 |
| Weight |
Yes |
Yes |
| Sensor |
|
Yes |
| Baseline |
|
Yes |
| Temperature |
Yes |
Yes |
| Heat Flow |
|
Yes |
| Furnace |
Yes |
|
|
| Temperature |
The temperature calibration is performed for a Pyris 1 TGA using magnetic standards of nickel and iron, which are supplied in the Spares kit. The runs should use the same conditions under which you would run your samples. The temperature calibration uses the Curie transition of the materials, i.e., the point at which the magnetic properties disappear.
The STA 6000 utilizes the heat flow signal for the temperature calibration where the onset of fusion for metal standards is used to make adjustments. |
| Weight |
The Spares kit provided includes a calibration weight that is used to verify and adjust the weight signal of the Pyris 1 TGA and STA 6000. The calibration weight is typically between 55mg and 100mg. |
| Furnace |
The Pyris 1 TGA furnace calibration takes approximately 1 hour. Enter the minimum and maximum temperatures between which the furnace will be calibrated. This will ensure that the sample temperature is under control over the whole range of the system. |
| STA |
Additional calibrations are required for the STA 6000. These involve the following steps:
- Sensor Calibration – similar to Furnace Calibration.
- DTA Baseline Optimization – maintains the heat flow baseline as flat as possible over the required temperature range.
- Heat Flow Calibration – enthalpy determinations from chemical and physical changes are based on the melting of standards provided with the STA 6000.
|