TA I
NSTRUMENTS
TGA 2950 B–21
Hi-Res
TM
Option
A third technique, which may help to improve
resolution, is to control the atmospheric pressure
surrounding the sample while in the furnace.
This can be done by placing the sample in a
semi-sealed container such as a hermetic DSC
pan with a very small pin hole (0.1 mm diameter
or less) or in a sample cup with a lid. When the
sample starts to react, the evolved gas will build
a slight vapor pressure inside the sample con-
tainer. This pressure may reduce or stop one or
more of the overlapped reactions and, thereby,
allow completion at a higher temperature. To
make this test, simply try running the sample
using a Hi-Res
TM
ramp with and without the
sample containment to see if a difference in
separation can be observed. Generally, the
temperature of reaction will shift to a higher
temperature, even if no improvement in separa-
tion occurs. The pressure containment tech-
nique is particularly helpful when using constant
reaction rate Hi-res mode (negative resolution
settings).
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