Injection of Liquids and
Gases in Order to Quantify
Evolved Species by Means of STA-FTIR
E. Kaisersberger1, E. Kapsch2, M. Maciejewski3 and E. Füglein1
1 NETZSCH-Gerätebau GmbH, Wittelsbacherstraße 42, D-95100 Selb, Germany
2 NETZSCH do BRASIL, Rua Michigan 166, BR-04 566-000 Sao Paulo/SP Brazil
3 Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
Well-established coupling techniques such as TG-FTIR or STA-MS
enable the identification of the gases that are evolved during thermal
analysis experiments. The Pulse Thermal Analysis (PulseTA®) (fig. 1)
was developed in order to enable not only the identification but also
the quantification of the evolved gases. By applying well-defined
volumes of the injected gas, and comparing the intensity of the
resulting FTIR signal with the intensity of the evolved gas, the
quantity of the latter can easily be determined. This method has so
far been limited to gases such as CO2, CO, NO and CH4.
The new injection port (fig. 2) that has been
developed together with ETH-Zürich additionally
enables the injection of liquids and therefore
allows quantification of such evolved gases,
Fig. 2:
Scheme of STA-FTIR transfer line
including the liquid injection port
which are in liquid state at ambient conditions.
The gases are injected into the inert carrier gas stream before entering the STA unit. The
liquids, on the other hand, are injected at the beginning of the heated transfer line (fig. 2).
Fig. 1:
The thermal decomposition reactions of CaCO3 and NaHCO3 when injecting gaseous CO2 and
Scheme of Pulse Thermal Analysis (PulseTA®)
liquid H2O are illustrated below.
Gram Schmidt
Gram Schmidt
Pulse CO2
Ethanol
pulse 1 µl each
Adaptor: 50°C, Transfer line: 50°C
purge:10 ml/min
0.14
17.41
17.26
0.80
25.72
25.08
purge: 20 ml/min
25.37
18.38 18.21 18.79 18.15
0.12
0.10
purge: 30 ml/min
14.41 14.91 14.98 14.59
0.60
9.405
9.462
0.08
0.40
0.06
0.04
0.20
0.02
0.0
1000µl
0
Fig. 3a:
1000µl
500µl
500
1000
1500
Time /s
2000
0.0
500µl
2500
3000
500 µl and 1000 µl pulses of CO2
500
1000
1500
2000
Time /s
2500
3000
Fig. 3b: 1 µl pulses of ethanol, different carrier gas flows
Gram Schmidt
water
TG /%
Fig. 4a:
Decomposition of CaCO3, 3D view of IR spectra
0
0.25
Initial mass NaHCO3: 23.09 mg
95
0.997x(59.92/24.24) = 2.46 mg H2O
90
stoichiometric amount: 2.47 mg H2O
0.89(85.17/11.86) = 6.39 mg CO2
-1
0.50
11.14
0.20
24.24
-2
0.40
85
Gram Schmidt
DSC /mW Temperature /°C
↓ exo
1000
50
900
0.20
-6.32 mg
800
40
TG /mg
0.60
100
3500
pulse: 0.500 ml CO2 each
700
11.9
30
12.53
0.15
80
20
-36.81 %
0.10
75
0.05
59.92
600
500
0.10
400
-4
0.20
300
10
0.05
-5
70
0.15
-3
0.30
200
0.10
85.17
0
100
-6
65
0.0
0
1000
2000
3000
Time /s
4000
0.0
0.0
0
5000
Fig. 5a: Decomposition of NaHCO3 , quantification of H2O
Fig. 5b: 3D view of all IR spectra
Fig. 4b:
10
20
30
40
50
60
Time /min
70
80
90
Decomposition of CaCO3, quantification of CO2