TA I
NSTRUMENTS
TGA 2950 B–59
Hi-Res
TM
Option
significant surface water transition will become
evident between 70
°
C and 100
°
C which will
affect the overall weight loss percentages.
When mixing and using this sample be sure to
keep the sample supply containers tightly
capped. Load the TGA quickly and use a dry
purge gas (air, nitrogen or argon). Dry air purge
at 100 mL/min was used for all example scans
shown. Sample sizes varied from 20 to 40 mg.
Small variations observable in weight loss
reproducibility in the example scans are largely
due to the non-homogeneity of the sample
mixture and variations in ambient humidity from
run to run.
Dynamic Rate Scans
In Figure B.12 (on the next page) we have
overlaid the individual bicarbonate decomposi-
tions (curves b and d) along with the decomposi-
tion of the mixture by conventional TGA
(curves a and e) and by dynamic rate Hi-res
TM
TGA (curve c). Reducing the heating rate of the
mixture from 20
°
C/minute (curve e) to 1
°
C/
minute (curve a) gave a very slight improvement
in resolution. Comparing these results to the
50
°
C/minute Hi-res
TM
scan we observe a signifi-
cant improvement in resolution with Hi-res
TM
TGA in about twice the time of the 20
°
C/minute
scan, and about one tenth the time of the 1
°
C/
minute scan. The method used for all scans was
a single ramp segment.
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