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.

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

András HofferMax Planck Institute for Chemistry

Mainz

In cooperation with

András Gelencsér, Marianne Blazsó

Objectives

• Identification and quantitative determination of polar organic compounds 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)

Derivatisation Py-GC-MS methodology

- 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

Instrumentation: Pyroprobe 2000GC Agilent 6890 / MS 5973 (EI) (quadrupole)

Py-GC-MS with TMAH

4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.000

200000

400000

600000

800000

1000000

1200000

1400000

Time-->

Abundance

HV19 (burning period)

HV71 (transition period)

4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.000

200000

400000

600000

800000

1000000

1200000

1400000

Time-->

Abundance

Identified compounds43 (39) compounds tentatively 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)

- 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

6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.000

5000000

1.5e+07

2.5e+07

3.5e+07

4.5e+07

Time-->

Abundance

6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.000

4000000

8000000

1.2e+07

1.6e+07

2e+07

Time-->

Abundance

HV19 (burning period)

HV71 transition period

Py-GC-MS with BSTFA

- 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).

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

Identified compounds

Derivatisation with TBAH

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

GC-MS measurements

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/

181

147

117

- 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 -

Planned time schedule of the work