DSC Basic Calibration, Adjustments and Maintenance

1. DSC Basic Calibration, Adjustments and Maintenance Queens University Belfast 16/02/12

2. Terminology • Calibration: - Determine the deviation of a measured value from a reference value. - Perform checks (e.g. In check, Zn check etc.) and total calibration (e.g. Calibrate DSC total….In/Zn) is calibration. • Adjustment: - Change the Instrument parameters in order to bring the measured value back to the reference value. - Accept the new parameters determined from the total calibration by pressing OK is adjustment.

3. Terminology • Reference material: - A substance with known and accepted reference values, e.g. melting temperature and melting enthalpy. - Certified reference materials are available at Laboratory of the Government Chemist (LGC), UK (http://www.lgcstandards.com) or National Institute of Standards and Technology (NIST), USA (http://ts.nist.gov/measurementservices/referencematerials) • Error limits: - The acceptable deviation of the measured value from the reference value. - The user defines the acceptable error limits.

4. Properties to be calibrated for DSC1 • Temperature • Heat flow (enthalpy) To bring themeasured values to agree with the reference values. • lag, the time lag of the program temperature (Tr) to the furnace temperature (Tc). To eliminate the influence of heating rate on the melting onset tempeature lag= lag 

5. lag = 0

6. Correct lag

7. Checks • A Check determines the deviation of the measured value to the reference value. • A check curve will be automatically evaluated, it can be certainly manually evulated as well. • The evaluation results of a failed check can be used for manual adjustment.

8. Checks Where to find STARe built-in check methods: In check and Zn check.

9. Checks The first heating of a fresh Indium pill shows a higher onset temperature than the subsequent heatings, the data should not be used.

10. Zn/Al eutectic Melting temperature of Zn: 419.5°C Checks Do not press the metal pills on the crucible firmly: possible eutetic!

11. Total calibration • A total calibration determines the temperature, heat flow and lag in one measurement. • Standard conditions: Al40 l pan and static air. Temperature: 2 points (In/Zn) Heat flow: 1 point (In) lag: 2 points (In/Zn)

12. Total calibration • New parameters will be prompted only if the total calibration is properly done. No parameter indicates a bad measurement. • The manual evaluation results can be also used for manual calibration. changed changed changed new old

13. Total Calibration Where to find STARe built-in check methods: In/Zn, n-C8H18/In and Indium

14. In Check In Check Total Calibration Sample Measurements Single Heat Flow Adjustment Total Calibration Fresh sample How to proceed OK KO In Check Fresh Sample OK T fail ∆H fail OK

15. Single heat flow adjusment Module Window >Calib/Adjust

16. Tips for calibration 1. Switch on the instrument and cooling options and stablize for at least two hours before checks. 2. Don’t use the data from the premelting of a fresh indium pill (1st heating), use the data from subsequent heatings. 3. You can create your own checks to meet your requirements. 4. Checks should be performed regularly e.g. weekly or biweekly. 5. A check is required after any adjustments. 6. References used in the total calibration should adapt to the measuring temperature range. e.g. n-C8H17/In total calibration is more suitable for low temperature calibration than In/Zn.

17. Where to view calibration parameters Install>Module>File>Open >Adjustment Overview

18. Where to view calibration parameters Install>Module>File>Open >Print/Print Preview

19. Maintanence • Always purge dry gas when working with subambient cooling options to prevent moisture condensation and icing. • Do not use flammable and explosive gases such as H2, CH4, CO and C2H4 etc., DSC cell is not gas tight and this could lead to an explosion. • After the measurements which involve aggressive gases use a final purge gas to protect the furnace (e.g. 100 ml/min N2 for 30 min). • For best signal quality, work in an environment free of vibrations (e.g. pull and push the table drawers during measurements) and powerful electric or magnetic fields (mobile, radio etc.)

20. Maintanence • To reduce the contamination on furnace, do not measure the samples up to decomposition temperatures unless necessary. Perform a furnace burn out and cleaning if sensor and furance are dirty. 200 W 400 W FRS5 500 °C for 30 min 700 °C for 20 min HSS7 500 °C for 30 min 500 °C for 30 min Purge gas static air or 50 ml/min air • If a crucible is stuck on the sensor due to contamination, don‘t force remove the crucible, try to first burn out the contamination with air purge, it might be easier to remove the crucible afterwards.

21. Maintanence Check the baseline regularly! • Peaks on the baseline indicate that the sensor could be contaminated (perform a burn out) and/or the crucibles are not clean. • If abnormal drift and noise presents, check if - sensor is dirty, loose and incorrectly positioned, - the furnace lid sits properly (e.g. particles on the furnace rim), - cooling works properly, - gas supply is stable, - external enviromental influences exist e.g. vibrations, impact from electronic devices etc.

22. Thank You!