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Analysis of polar o rganic compouds in size resolved aerosol by Py-GC-MS and derivatisation GC-MS

Analysis of polar o rganic compouds in size resolved aerosol by Py-GC-MS and derivatisation GC-MS. A ndrás Hoffer Max Planck Institute for Chemistry Mainz In cooperation with András Gelencsér, Marianne Blaz só. Objectives.

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Analysis of polar o rganic compouds in size resolved aerosol by Py-GC-MS and derivatisation GC-MS

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  1. Analysis of polar organic compouds in size resolved aerosol by Py-GC-MS and derivatisation GC-MS András Hoffer Max Planck Institute for Chemistry Mainz In cooperation with András Gelencsér, Marianne Blazsó

  2. Objectives • Identification and quantitative determination of polar organiccompounds in aerosol extracts by derivatisation GC-MS (Mainz) • - from all filter samples (including backup) • - from MOUDI samples for the most abundant compounds • Method has been established but • speciation to be supported by GC chemical ionisation MS and GC-HRMS on selected samples (Hungary) • Direct structural characterisation of bulk organic aerosol by on-line derivatisation Py-GC-MS (Hungary) • - qualitative but yields information on HULIS / polyacids as well • - relative ratios of pyrolysis products may be used for source apportionment (see Blazsó et al. JAAP)

  3. Derivatisation Py-GC-MS methodology Instrumentation: Pyroprobe 2000 GC Agilent 6890 / MS 5973 (EI) (quadrupole) • pyrolysis: flash, 400°C, 20s • derivatisation reagents: TMAH 10 l, TBAH, BSTFA • GC column: HP5MS 0.32 x 30 m 0.25 m • temperature program: • 50°C 1 min - 10°C/min 300°C hold 5min • - identification: Wiley 275 spectrum library • - sample need: spot of 0.3 cm2

  4. Abundance 1400000 HV19 (burning period) 1200000 1000000 800000 600000 400000 200000 0 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 Time--> Abundance HV71 (transition period) 1400000 1200000 1000000 800000 600000 400000 200000 0 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 Time--> Py-GC-MS with TMAH

  5. 43 (39) compoundstentatively identified • Major compound classes: • Monocarboxylic including fatty acids • (C6-C28) • most abundant n-C16 • few unsaturated compounds (C18:1) • Dicarboxylic acids • (butanedioic acid, pentanedioic acid, • methyl-butanedioic acid, 2-butenedioic acid) • Aromatic compounds • di-, tri- hydroxy benzene and benzoic acids • and/or methoxybenzoic acids and derivatives • (TBAH derivatisation required) Identified compounds

  6. - Anhydrosugars/sugars(levoglucosan) • n-alkanes (C23-C28) • The relative amount of the aromatic compounds to the levoglucosan are • higher (1.3 - 5) in the burning period compare to the transition period • Some aromatic compounds (coumaryl compound) are missing from the transition period sample • burning p eriod transition period • C/G=1.09 • S/G=0.65 S/G=0.9 • grass and softwood origin hardwood burning

  7. Abundance 4.5e+07 HV19 (burning period) 3.5e+07 2.5e+07 1.5e+07 5000000 0 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 Time--> Abundance 2e+07 HV71 transition period 1.6e+07 1.2e+07 8000000 4000000 0 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 Time--> Py-GC-MS with BSTFA

  8. Similar compound classes were identified as in the TMAH-treated sample. • The identified aromatic compounds where the same as in previous • mesurements made with water extraction. • The relative amount of the aromatic compounds is higher in the • burning period (1.4-5.5). Identified compounds Derivatisation with TBAH Hydrolysis of high MW compounds  mostly methoxy guaiacyl syringyl units can be identified (compare to Graham et al.) several aromatic hydroxy compounds in aqueous extract

  9. GC-MS measurements Instrumentation: GC Fisons 8000 / MS Trio 1000 (EI, quadrupol) • - GC column: SPB5 0.32mm x 30 m 0.25 m • temperature program: • 50°C 1 min 10°C/min 300°C hold 5min • - sample need:~6cm2 • Sample preparation • Extract in ACN (6cm3, 1h) • Derivatised with PFBHA (O-(2,3,4,5,6-pentafluorobenzyl) hydroxy amine • after drying with BSTFA

  10. Ion fragments EI : m/z=73, 75 [Si(CH3)3]+, [OH=Si(CH3)2]·+ relative intensity: (20-100%) m/z =117 [COOSi(CH3)3]·+ monocarboxylic acids relative intensity: 61-97% (except aromatic carboxylic acids) and strong M-15 as well m/z= 147 [(CH3)2Si=OSi(CH3)3]·+ 2 active H-atoms relative intensity: ~100% m/z= 181 [C6F6CH2]+ carbonyl groups relative intensity 50-100% /Yu et al. 1998/

  11. 181 147 117

  12. Planned time schedule of the work • Identification of individual compound is underway • The identified compounds will be confirmed by standards • Quantification will be performed in SIM with internal • standard method - Identification of individual compounds: end of March - Quantitative analysis: end of August - Data evaluation and writing papers: September -

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