DSC Q Series Getting Started Guide
49
For optimum experimental results you will need to perform all DSC calibrations whenever you
change
one of
the following parameters:
•
First use of a new cell
•
Purge gas change
•
Cooling device or accessory (FACS, LNCS, RCS, or Quench Cooling Can) change.
For optimum experimental results you will need to perform all DSC calibrations except Tzero whenever you
change
one of the following parameters:
•
Heat flow selection change (T4P, T4, etc.)
•
Pressure (in PDSC experiments) change.
Calibration is performed in the instrument’s calibration mode, which is accessed through the controller. (This
does not apply to heat capacity calibration, which is performed in both the standard and MDSC modes, where
applicable).
Calibration consists of several different types of procedures specific to each cell, which are described briefly
below. For more details on performing each type of calibration refer to the instructions in the online documen-
tation.
Tzero
TM
The DSC Tzero calibration requires two experiments. The first experiment is done without samples or pans
(baseline); the second is performed with large (approximately 95 mg) sapphire disks (without pans) on both the
sample and reference positions. Both experiments use the same method beginning with a cell preheat followed
by an equilibration at an initial temperature, holding isothermal for five minutes, heating at constant rate to a
final temperature and holding isothermal for 5 minutes. The range of temperatures should be at least as broad
as the desired experimental range. Tzero calibration should be done at relatively high heating rates such as
20°C/min in order to obtain the most accurate calibration of the sensor thermal capacitance and resistance values.
Rates of less than 10°C/min are not recommended for Tzero calibration.
Tzero calibration is used with the DSC Q2000 and Q1000 for Heat Flow T4 and T4P, and with the DSC Q200 and
Q100 for Heat Flow T4.
NOTE: The “heat flow” signal should be selected and used to measure the heat of fusion or
enthalpy of sharp melting transitions such as obtained with Indium.
Baseline Slope and Offset Calibration
The baseline slope and offset calibration involves heating an empty cell through the entire temperature range
expected in subsequent experiments, holding isothermal at the temperature limits. The calibration program is
used to calculate the slope and offset values needed to flatten the baseline and zero the heat flow signal. This
calibration is used in the DSC Auto Q20, Q20, and Q10 and when the selected heat flow is T1 for the other DSC
models.