12-Marchand-et-al

Document Sample
12-Marchand-et-al Powered By Docstoc
					 Functional group monitoring in atmospheric particulate organic matter using tandem
                   mass spectrometry: principles and applications
                                   N. Marchand, J. Dron, I. El Haddad and H. Wortham

  Laboratoire Chimie Provence (UMR 6264), équipe Instrumentation et Réactivité Atmosphérique, Universités d'Aix-Marseille I,II et III-
                                                             CNRS,
                                          3 place Victor Hugo, 13331 Marseille Cedex 3



Particulate organic matter (POM) in atmospheric                        under study (figure 1) (ii) a high accuracy
aerosols results from primary emissions as well as in                  quantification of the functional groups (iii) low
situ formation through oxidative processes of gas-                     detection    limits    allowing    applications   to
phase organic compounds, and contributes in                            environmental measurements.
approximately 20 to 50% of the total fine aerosol                      Results obtained by this new approach for a wide
mass at continental mid-latitude. It has been well                     panel of atmospheric samples including primary
established that this class of particulate material has a              sources (vehicular exhaust, wood combustions), SOA
high potential impact on both human health and                         (photo oxidation of xylene), and urban background
climate change. In order to better estimate the                        aerosols collected during winter and summer will be
influence of organic aerosols, a good knowledge of                     presented and compared in terms of functionalisation
their composition and reactivity is required.                          degree.
However, considering the degree of complexity of
                                                                               Arbitrary Units (kCps)
POM, conventional analytical methods lead to its                                                        75      62 (394 kCps)                                                                                          a) Precursor ions of NO2-

incomplete characterization.                                                                                       -NO2                                                                  C= 10,7 pmol/µgPM10
Functional group determination is a complementary                                                       50
                                                                                                                                                                                                  RfOC ~ 2300
approach between molecular identification and
                                                                                                                                           194
organic carbon measurements which enables the                                                           25
                                                                                                                          134
                                                                                                                                   154



                                                                                                                                             204
                                                                                                                          120



                                                                                                                                   168




                                                                                                                                                          232
                                                                                                                                                         246
                                                                                                                                                         262
                                                                                                                                 182
characterization of a larger fraction of the aerosol
mass and provides valuable information on its                                                                       100                    200                                300                        400                     500
                                                                                                                                                                                                                                                      m/z
                                                                                                                                                                                                                                                            600
                                                                        Arbitrary Units (kCps)




chemical composition. This analytical technique
                                                                                                                                                       244




                                                                                                                                                                                                                       b) Precursor ions of NO3-
being besides the best suited for modelling purposes,
                                                                                                 150
                                                                                                                  -ONO2
                                                                                                                                                              250




                                                                                                 125
it appears imperative to improve its performances.                                               100
Also, Fourier Transform Infrared spectroscopy (FT-
                                                                                                                                                              255




                                                                                                                                                                                                                           479
                                                                                                                                                                                            359


                                                                                                        75


                                                                                                                                                                                                                436
                                                                                                                                     194




                                                                                                                                                                            297




IR) suffers from poor robustness (Blando, 2001),
                                                                                                                                                                                                  379
                                                                                                                                                                                                        396
                                                                                                                                                                     278


                                                                                                                                                                                   322




                                                                                                        50




                                                                                                                                                                                                                                        531
                                                                                                                                                                                                                                              551
proton nuclear magnetic resonance (H-NMR)
                                                                                                                                                 218




                                                                                                                                                                                                                                                          558
                                                                                                        25

(Tagliavini, 2006) requires heavy instrumentation,
                                                                                                                  100                 200                                  300                          400                      500                        600
and both have a relatively low sensibility.                                                                                                                                                                                                          m/z
                                                                            Intensity (arb. units




                                                                                                        40
                                                                                                             c)                             307              335                           C= 30,3 pmol/µgPM10
The aim of the work presented here is to propose a
                                                                                                                        C=O                        319
                                                                                                                                                                                               449  RfOC ~ 500
new method for the analysis of functional groups and                                                    30                                                                                 407 421

to highlight its relevance for atmospheric chemistry                                                                                                                       365
                                                                                                                                                                                  379
                                                                                                                                                                                        393
                                                                                                                                                                                          403
purposes. This new atmospheric pressure chemical                                                        20
                                                                                                                                             309 325
                                                                                                                                                                       363
                                                                                                                                                                                                     435

                                                                                                                                                                    351
ionization-tandem mass spectrometry (APCI-                                                                                        279 297
                                                                                                                                                                       364                405

MS/MS) methodology is based either on neutral loss                                                      10
                                                                                                                                269
                                                                                                                                    291                        344                 387
                                                                                                                                                                                                                     477
                                                                                                                                                                                                                            505
                                                                                                                                                                                                               463
mode for carboxylic acid and carbonyl functional                                                                          251
                                                                                                                                                                                                                                  519               561


group (Dron et al, 2007, 2008a) either on precursor                                                      0
                                                                                                          200                         300                                                400                               500
                                                                                                                                                                                                                                                          m/z 6 0 0
ion scanning mode for nitro functional group (Dron                                                                                                                                                             Dron el al, JMS, 2008
et al, 2008b). These approaches enable to group
chemical compounds by their ability to loose a
                                                                       Figure 1. Mass spectra obtained for –NO2 (PAR 46), -
known neutral molecular fragment for neutral loss
                                                                       ONO2 (PAR 62) and C=O (NL 181) of a sample collected
mode (NL mode) or to produce a characteristic ion in                   at an urban background site (Chamonix, France) during
the collision cell for the precursor ion scanning mode                 summer. RfOC represents the functionalisation of the
(PAR mode). For example, after having been                             organic carbon (=nOC/nfunct.)
derivatized to methyl esters, carboxylic acids are
identified by their ability to loose a HOCH3 fragment                  Blando, J. D., Porcja R. J. & Turpin B. J. (2001). Aerosol Sci.
(Dron et al, 2007) while the nitro compounds are                           Technol., 35, 899-908.
                                                                       Tagliavini, E., Moretti F., Decesari S., Facchini M. C., Fuzzi S.,
analysed according to their ability to produce NO2-                        Maenhaut W. (2006). Atmos. Chem. Phys., 6, 1003-1019.
(m/z=46 amu) in the collision cell (Dron et al,                        Dron. J., Eyglunent G., Temime-Roussel B., Marchand N.,
2008b). Compared to FT-IR and H-NMR                                        Wortham H. (2007). Caboxylic., Analytica Chimica Acta ,
spectroscopy, this analytical strategy offers major                        605(1), 61-69.
                                                                       Dron. J., Zheng W., Marchand N., Wortham H. 2008a. Journal of
benefits, it provides (i) an apparent molecular weight                     Mass Spectrometry, in press.
distribution of the compounds bearing the function                     Dron. J., Abidi E., El Haddad, I., Marchand N., Wortham H.
                                                                           2008b.. Submitted to Analytical Chemistry (Fev 2008).

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:0
posted:2/13/2012
language:English
pages:1