Mass selective detector coupled to gas chromatography (GC-MSD) and to thermogravimetry (TG-MSD)
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Mass selective detector coupled to gas chromatography (GC-MSD)
and to thermogravimetry (TG-MSD)
Dr. Mihai Brebu
1. Gas chromatography (GC)
2. Thermogravimetry (TG)
3. Mass selective detector (MSD)
4. Gas chromatography - Mass selective detector (GC-MSD)
5. Thermogravimetry - Mass selective detector (TG-MSD)
Institutul ‘Petru Poni’ Iasi, aprilie 2009

1. Gas chromatography (GC) Institutul ‘Petru Poni’ Iasi, aprilie 2009
Gas chromatography: analysis technique for qualit./quantit. determination of compounds in mixtures
Compounds separation by selective adsorption/desorption affected by temperature, gas flow (for a given column)
Detection of compounds based on specific properties
Recording/analysis/display of signal
Vaporisation, mixing with carrier gas, injection in the column
Column
Detector
Recorder
Inlet

retention time (rt) depends on: characteristics of the column (length, diameter, filling) polarity of compounds (rt izooctan < octena < octan) molecular weight of compounds (rt heptan < octan < nonan) temperature program (rt decreases at high temperatures) carrier gas flow (rt decreases at high flows)
0.8e+7
0.6e+7
0.4e+7
0.2e+7
0 2 4 6 8 10 12 14 16 18 20 22 24 0
retentiontime (min)
response
a: 100(1),10>220 oC; 1ml/minb: 150(1),10>220 oC; 5ml/minc: 150(1),10>220 oC; 10ml/min
Sa
Va
Sb
Vb
Sc Vc
effect of temperature and flow rate
effect of flow rate
Vanilin (V) in EtOH as solvent (S)
GC-FID
1.0e+7
2 3 4 5 6 7 retention time(min)
abundance
31(8) oC; 1ml/min
26(8) oC; 1ml/min
26(4),10>70 oC; 0.6ml/min1.0e+7
1.5e+7
0.5e+7
1.0e+7
1.5e+7
0.5e+7
1.0e+7
1.5e+7
0.5e+7
Ambient gas sample
qualitative analysis: - from retention times - from MSDquantitative analysis: - from peak area
1. Gas chromatography (GC) Institutul ‘Petru Poni’ Iasi, aprilie 2009
good balance between short analysis time and good separation of compounds

2. Thermogravimetry (TG) Institutul ‘Petru Poni’ Iasi, aprilie 2009
Thermogravimetry: analysis technique for thermal processes involving mass loss (thermal degradation)
thermal behaviour - described by: temperature for onset of the degradation step temperature for maximum rate of degradation temperature for end of the degradation step final mass loss of degradation step
thermal behaviour - affected by: temperature program (heating rate) atmosphere (air, inert gas) sample mass
Polyurethane

2. Thermogravimetry (TG) Institutul ‘Petru Poni’ Iasi, aprilie 2009
0
20
40
60
80
100
250 300 350 400 450 500 550 600Temperature , oC
Sam
ple
wei
gh
t , w
t%
DT
G -
der
ivat
ive
wei
gh
t lo
ss
PEPPPSHIPS-BrABSABS-BrPVCPET
HDPEPPABS
PS
PET
ABS-Br
HIPS-Br
PVC
HIPS-Br: DTG
aplications: thermal stability - lifetime predictions

2. Thermogravimetry (TG) Institutul ‘Petru Poni’ Iasi, aprilie 2009
aplications: kinetic studies: activation energy (Ea), reaction order (n), pre-exponential factor (A)
100 200 300 400 500 600Temperature/°C
10
30
50
70
90
Mass/%
10 oC/min
100 200 300 400 500 600Temperature/°C
10
30
50
70
90
Mass/%
20 oC/min10 oC/min 5 oC/min
the kinetic model should correspond to a plausible degradation mechanism !!!
Polyurethane

3. Mass selective detector (MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
Mass selective detector: qualitative identification of compounds based on fragmentation pattern (EI)MS spectra for aliphatics

3. Mass selective detector (MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
MS spectra for aromatics

3. Mass selective detector (MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
MS spectra for brominated compounds
79+15 81+15
79*2+14 81*2+14
79*2+13 81*2+13
79+81+1479+14
81+14
79+81+13
79+12 81+12
81+13
M=95
M=174
M=253
79*3+13 81*3+13
79*2+81+13 79+81*2+13
Br: 79.904; g mol-1
79Br (50.69%); 81Br (49.31%)

Time
Abundance
1.2e+7
1.0e+7
0.8e+7
0.6e+7
0.4e+7
0.2e+7
5 10 15 20 25 30 35 40 45 50 55 60 65 0
20000
40000
60000
80000
100000 ion 81
4. Gas chromatography - mass selective detector (GC-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
HBr
PhCHBrCH3
???
???
HIPS-Br degradation oilTIC

4. Gas chromatography - mass selective detector (GC-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
I
II
HIPS-Br degradation oil - detail TIC
HIPS-Br degradation oil - scan at 34.59 min

4. Gas chromatography - mass selective detector (GC-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
I
II

4. Gas chromatography - mass selective detector (GC-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
ambient gas sample – TIC(26(4),10>100; 0.6ml/min)
2.00 2.20 2.40 2.60 2.80 3.00 3.20 3.40 3.600
1000
2000
3000
4000
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6000
7000
8000
9000
10000
11000
12000
13000
14000
15000
16000
17000
18000
19000
20000
21000
22000
23000
24000
Time-->
Abundance
Ion 27.00 (26.70 to 27.70): GAZE05.D\data.ms
ion 27 – HCN at rt 2.05
2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00
2.02 2.02 2.03 2.04 2.04 2.04 2.05 2.06 2.06 2.06 2.07 2.08 2.08
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
4500000
5000000
5500000
6000000
6500000
7000000
7500000
8000000
8500000
9000000
9500000
1e+07
1.05e+07
1.1e+07
1.15e+07
1.2e+07
Time-->
Abundance
TIC: GAZE05.D\data.ms
detailed TIC at rt 2.03 – 2.06

4. Gas chromatography - mass selective detector (GC-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
ambient gas sample – TIC
2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.500
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
4500000
5000000
5500000
6000000
Time-->
Abundance
Ion 41.00 (40.70 to 41.70): GAZE05.D\data.ms
2.60 2.80 3.00 3.20 3.40 3.60 3.80 4.00 4.20 4.40 4.60 4.800
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
7000
7500
8000
8500
9000
9500
10000
Time-->
Abundance
Ion 54.00 (53.70 to 54.70): GAZE05.D\data.ms
ion 41 – acetonitrile: 2.78
ion 54– 2-propenenitrile: 2.97– propanenitrile: 3.60
5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.000
200000
400000
600000
800000
1000000
1200000
1400000
1600000
1800000
2000000
2200000
2400000
Time-->
Abundance
Ion 86.00 (85.70 to 86.70): GAZE05.D\data.msIon 101.00 (100.70 to 101.70): GAZE05.D\data.ms
ion 86; ion 101– triethylamine: 6.07
2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00

5. Thermogravimetry - mass selective detector (TG-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
0.0E+00
2.0E-10
4.0E-10
6.0E-10
8.0E-10
1.0E-09
1.2E-09
1.4E-09
1.6E-09
1.8E-09
2.0E-09
50 150 250 350 450 550 650 750 850Temperature , oC
MS
inte
nsity
, a.
u.
0
20
40
60
80
100
TG
, %
2 12 15 16 17 18 26
28 29 30 43 44 Tic Tg
Pc: 5.6 mg

0.0E+00
1.0E-12
2.0E-12
3.0E-12
4.0E-12
5.0E-12
6.0E-12
7.0E-12
8.0E-12
9.0E-12
1.0E-11
50 150 250 350 450 550 650 750 850Temperature , oC
MS
inte
nsity
, a.
u.
0
20
40
60
80
100
TG
, %
2 12 15 16 17 18 26
28 29 30 43 44 Tic Tg
Pc: 5.6 mg
5. Thermogravimetry - mass selective detector (TG-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009

5. Thermogravimetry - mass selective detector (TG-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
0.0E+00
2.0E- 10
4.0E- 10
6.0E- 10
8.0E- 10
1.0E- 09
1.2E- 09
1.4E- 09
1.6E- 09
1.8E- 09
2.0E- 09
50 150 250 350 450 550 650 750 850Temperature , oC
Ms
inte
nsi
ty , a
.u.
0
20
40
60
80
100
Tg
, %
2 12 15 16 17 18
28 29 43 44 Tic Tg
Pc/CaNi: 37mg - 4.6 mg Pc

5. Thermogravimetry - mass selective detector (TG-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
0.0E+00
5.0E- 12
1.0E- 11
1.5E- 11
2.0E- 11
2.5E- 11
3.0E- 11
50 150 250 350 450 550 650 750 850Temperature , oC
Ms
inte
nsi
ty , a
.u.
0
20
40
60
80
100
Tg
, %
2 12 15 16 17 18
28 29 43 44 Tic Tg
Pc/CaNi: 37mg - 4.6 mg Pc

5. Thermogravimetry - mass selective detector (TG-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
PEG

5. Thermogravimetry - mass selective detector (TG-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
PEG

5. Thermogravimetry - mass selective detector (TG-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
PU

5. Thermogravimetry - mass selective detector (TG-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
-FeOOH -Fe2O3 • H2O Fe3O4
m/z 17 vs m/z 18 - ct.
changes in composition and structure of -FeOOH during catalytic degradation of ABS

5. Thermogravimetry - mass selective detector (TG-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009
reaction of 4-phenylbutironitrile over -FeOOH catalysts and its derivatives
NH3:14,15,16, 17/18
reduction of catalyst by organic compounds
alkyls: 27,28,29,14,15
toluene, ethylbenzene: 91
aliphatic nitriles: 41,14,15,16,28,29

Institutul ‘Petru Poni’ Iasi, aprilie 2009
Acknowledgements:
- Dr. Dan Rosu - Dr. Vasile Cornelia
- Dr. Nita Tudorache - Prof. Yusaku Sakata
Conclusions:
- MSD is a powerful detector for qualitative identification of compounds leaving a GC column or a TG furnace
- identification is facile in GC-MSD if compounds are well separated by GC and their structure is included in databases
- careful interpretation of mass spectra is need if compounds are not well separated by GC and their structure is not included in databases
- careful analysis of various mass signals is need for TG-MSD data since compounds are not separated and the mass signals might represent a sum of contributions from fragmentation of different compounds