G. Varhegyi et F. Till, Computer processing of thermogravimetric-mass spectrometric and high pressure thermogravimetric data. Part 1. Smoothing and differentiation, THERMOC ACT, 329(2), 1999, pp. 141-145
High quality data smoothing is frequently required in the thermal analysis.
Though the mathematical methods for smoothing are well known, the selectio
n of the proper smoothing parameters cannot be based on statistical checks
alone in thermal analysis. Many times a compromise must be found between th
e effective removal of the various experimental error components and the di
stortion of the curves by too strong smoothing. The following topics are di
scussed from a practical point of view: (i) the determination of the deriva
tive thermogravimetric (DTG) curves at low sample masses; (ii) the eliminat
ion of the noise and flutter from the results of high-pressure TG experimen
ts; (iii) the evaluation of the noisy, low intensity mass spectrometric sig
nals arising from the minor volatile products of decomposition or oxidation
. The performance of the methods is shown in two applications: (1) Evaluati
on 0.25-0.5 mg mass loss steps in high-pressure thermogravimetry; (2) Study
of NOx formation by atmospheric pressure thermogravimetry-mass spectrometr
y during the temperature programmed combustion of 0.4 mg coal char. (C) 199
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