Target and untarget analysis of water soluble compounds in urban aerosols using an innovative coupling of IC-HRMS.

Introduction Primary emissions such as biomass burning (BB), chemical and photo chemical reactions introduce polar organiccompounds into the atmosphere. These molecules, such as levoglucosan (Lg) the most specifi c tracer of BB, are often diffi cult to characterize using reverse phase chromatography. In this work it is proposed the innovative coupling between ion chromatography (IC) and HRMS for the fi rst time aimed at the determination of Lg and its isomers and the chemical characterization of water soluble anionic organic compounds in the atmospheric aerosol. Method The analytical method was developed coupling a Thermo Scientifi c(TM) Dionex(TM) ICS-5000 system confi gured with a pump module, a sodium hydroxide Eluent Generator module, a 2-mm ASRS® 300 Suppressor , AS-AP Autosampler , and a Orbitrap XL FTMS (Thermo Fisher Scientifi c, Bremen, Germany). Chromatogaphic separation was perfomed using a a Dionex CarbopacTM PA10 analytical column (250x2mm) equipped with a Dionex CarbopacTM PA10 guard column (50x2mm). The IC was connected to an atmospheric pressure chemical ionization source with negative polarity. The Orbitrap mass analyzer was used with a scan range of m/z 60-600 and a nominal resolving power setting of 100,000 (FWHM, at m/z 400; 0.5 s scan cycle time) using palmitic acid at m/z 255.2330 as the lock mass. Results The instrumental method was developed with the aim of obtaining an effi cient separation between Lg and its isomers: mannosan and galactosan, which are specifi c BB tracers in the atmosphere. The dynamic linear range, detection and quantifi cation limits were evaluated for each analyzed compound. The internal standard method was used to quantify anhydrosugars in airborne particulate matter using 13C6 Lg. In order to evaluate the impact of BB on urban aerosols of Belgradecollected during fall and winter seasons, the instrumental method was applied to the quantitative determination of these compounds in an acqueous extract. Moreover one of the advantages of full scan HRMS is that the data can be mined at a later time without any need for re-injecting the samples, obtaining an untarget analysis with the aim of better understanding the chemical composition of urban aerosols. Conclusion We obtained the set up of a instrumental method characterized with good instrumental detection limits (Lg 3.6 ng mL-1, mannosan 4.7 ng mL-1 , galactosan 9.9 ng mL-1) for the target determination of anhydrosugars. The seasonal trend of these compounds and the untarget characterization in urban aerosols of Belgrade were obtained . Novel aspects To our knowledge for the fi rst time an Orbitrap MS has been coupled to an IC with the aim of quantitatively determining anhydrosugars and at the same time qualitatively perform chemical characterization of atmospheric aerosols. Acknowledgments This work fi nancially supported by the Early Human Impact ERC Advance Grant from the European Commission's VII Framework Programme, grant number 267696