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Mass selective detector coupled to gas chromatography (GC-MSD) and to thermogravimetry (TG-MSD)

Institutul ‘Petru Poni’ Iasi, aprilie 2009. 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)

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Mass selective detector coupled to gas chromatography (GC-MSD) and to thermogravimetry (TG-MSD)

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  1. Institutul ‘Petru Poni’ Iasi, aprilie 2009 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)

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

  3. 1. Gas chromatography (GC) Institutul ‘Petru Poni’ Iasi, aprilie 2009 S response S c S V a Vanilin (V) in EtOH as solvent (S) 1.0e+7 b c V a o a: 100(1),10>220 C ; 1ml/min GC-FID 0.8e+7 o b: 150(1),10>220 C ; 5ml/min V b o c: 150(1),10>220 C ; 10ml/min 0.6e+7 effect of temperature and flow rate 0.4e+7 effect of flow rate 0.2e+7 0 retention time(min) 0 2 4 6 8 10 12 14 16 18 20 22 24 abundance Ambient gas sample o 31(8) C ; 1ml/min 1.5e+7 1.0e+7 0.5e+7 1.5e+7 o 26(8) C ; 1ml/min 1.0e+7 0.5e+7 1.5e+7 o 26(4),10>70 C ; 0.6ml/min 1.0e+7 0.5e+7 retention time (min) 2 3 4 5 6 7 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) good balance between short analysis time and good separation of compounds qualitative analysis: - from retention times - from MSD quantitative analysis: - from peak area

  4. 2. Thermogravimetry (TG) Institutul ‘Petru Poni’ Iasi, aprilie 2009 Thermogravimetry: analysis technique for thermal processes involving mass loss (thermal degradation) Polyurethane 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

  5. 2. Thermogravimetry (TG) Institutul ‘Petru Poni’ Iasi, aprilie 2009 aplications: thermal stability - lifetime predictions

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

  7. 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

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

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

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

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

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

  13. 4. Gas chromatography - mass selective detector (GC-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009 detailed TIC at rt 2.03 – 2.06 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 ambient gas sample – TIC (26(4),10>100; 0.6ml/min)

  14. 4. Gas chromatography - mass selective detector (GC-MSD) Institutul ‘Petru Poni’ Iasi, aprilie 2009 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 ambient gas sample – TIC ion 54 – 2-propenenitrile: 2.97 –propanenitrile: 3.60 ion 41 – acetonitrile: 2.78 ion 86;ion 101 – triethylamine: 6.07

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

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

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

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

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

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

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

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

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

  24. Institutul ‘Petru Poni’ Iasi, aprilie 2009 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 Acknowledgements: - Dr. Dan Rosu - Dr. Vasile Cornelia - Dr. Nita Tudorache - Prof. Yusaku Sakata

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