“…To date, most ESI FT-ICR MS analyses of DOM have addressed analytical challenges associated either with sample preparation and ion production, or with data analysis and interpretation. Researchers have made important contributions in these areas by optimizing protocols for DOM extraction and concentration (Kim et al, 2003;Koprivnjak et al, 2006;Dittmar et al, 2008;Morales-Cid et al, 2009), chromatographic pre-separation (Fievre et al, 1997;Koch et al, 2008;Reemtsma et al, 2008;Stenson, 2008;Gaspar et al, 2009), and ESI direct infusion (Brown and Rice, 2000;Kujawinski et al, 2002;Stenson et al, 2003;. Major advances have also been made for elemental formula assignments (Koch et al, 2005;Kujawinski and Behn, 2006;Koch et al, 2007;Kunenkov et al, 2009), graphical andcompositional analysis (Kim et al, 2003;Stenson et al, 2003;Wu et al, 2004;Koch and Dittmar, 2006), and multivariate statistical analysis (Koch et al, 2005;Koch et al, 2008;Rossello-Mora et al, 2008;Gougeon et al, 2009;Kujawinski et al, 2009).…”