DSC Basic Calibration, Adjustments
and Maintenance
Queens University Belfast
16/02/12
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.
1
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.
2
Properties to be calibrated for DSC1
 Temperature
 Heat flow (enthalpy)
To bring the measured 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 
3
lag = 0
4
Correct lag
5
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.
^ex o
DS C In Chec k (pas s ed!)
10.12.2003 16:45:07
Sample: In Check (passed), 6.2800 mg
Integral
-181.13 mJ
normalized -28.84 Jg^-1
Onset
156.57 °C
20
mW
120
The DSC module is within specifications!
(27.85...29.05 J/g, 156.3...156.9 °C)
125
130
MSG Lab: MET TLER
6
135
140
145
150
155
160
165
170
175
°C
STA Re S W 9.10
Checks
Where to find
STARe built-in check
methods:
In check and Zn check.
7
Checks
The first heating of a fresh Indium pill shows a higher onset temperature
than the subsequent heatings, the data should not be used.
^ex o
In c hec k
11.12.2007 11:17:19
mW
0
In check1, 6.3640 mg
-2
Integral
-177.05 mJ
normalized -27.82 Jg^-1
Onset
156.62 °C
In check2, 6.3640 mg
-4
Integral
-178.02 mJ
normalized -27.97 Jg^-1
Onset
156.84 °C
-6
-8
-10
-12
135
140
145
150
155
M SG Lab: NJ
160
165
170
°C
STA R S W 9.10
e
8
Checks
Do not press the metal pills on the crucible firmly: possible eutetic!
Zn/Al eutectic
Melting temperature of Zn: 419.5°C
9
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)
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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
11
Total Calibration
Where to find
STARe built-in check
methods:
In/Zn, n-C8H18/In and Indium
12
How to proceed
Total Calibration
In Check
OK
KO
In Check
Fresh Sample
T fail
Total Calibration
Fresh sample
Sample Measurements
OK
∆H fail
Single Heat Flow
Adjustment
In Check
13
OK
Single heat flow adjusment
Module Window >Calib/Adjust
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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.
15
Where to view calibration parameters
Install>Module>File>Open
>Adjustment Overview
16
Where to view calibration parameters
Install>Module>File>Open
>Print/Print Preview
17
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.)
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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.
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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.
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Thank You!